OPHTHALMIC CLINICAL SKILLS COMPETENCIES FOR … · ophthalmic care, case scenarios, transposing...

Ophthalmic Technician Skills Competencies Folder 1

OPHTHALMIC CLINICAL SKILLS

COMPETENCIES FOR OPHTHALMIC TECHNICIANS

Lilliane Michael


CONTENTS

PAGE

INTRODUCTION

LIST OF CLINICAL SKILLS

LIST OF COMMON OPHTHALMIC TERMS

VISUAL ACUITY

MEASURING INTRA-OCULAR PRESSURE

HUMPHREY VISUAL FIELDS

AUTOREFRACTION

OCULUS PENTACAM

OPTICAL COHERENCE TOMOGRAPHY (OCT)

F0CIMETRY

SPECULAR MICROSCOPY

3-4

5

6-9

10-27

28-38

39 -51

52-60

61-68

69-76

77-85

86-92


Sussex Eye Hospital

Ophthalmic Technicians

INTRODUCTION

Welcome to the Sussex Eye Hospital. We hope you will find your new post

both rewarding and fulfilling. We also hope you are starting to feel settled in

your new exciting role. This folder is for you to keep alongside other paper

documents such as the orientation booklet and your Trust contract with job

description.

The ‘Competencies’ folder has been carefully designed to inform and guide

your learning and development within your post as band 4 Ophthalmic Techni-

cian and positively across your career. Initially it should focus on enabling you

to develop and apply your new learning to meet the basic knowledge and skills

demands of your new post in the Sussex Eye Hospital. Support in training, clini-

cal practice and with a learning commitment and completion of ophthalmic

skills assessments will ultimately reward you to becoming a confident profes-

sional Ophthalmic Technician.

The Competencies listed in this folder apply to all Band 4 Ophthalmic Techni-

cians who are employed in that post. Each individual will still have their own

personal development plan reflecting the development that they personally

need to help them to develop. This will be taken into consideration in your ap-

praisal meetings.


The following competencies have been identified to help fulfil the role of an

Ophthalmic Technician for our outpatient and accident and emergency de-

partments. This may be reviewed from time to time due to the nature of

standards and changes in legislation, benchmarks and new technology. Be-

cause the pace of change is so great, the clinical skills training will also have to

be flexible enough to enable a quick response and to adapt as necessary to

new situations.

Please take your time to read this folder. It includes the list of skills competen-

cies with relevant general ophthalmic information, some ophthalmic medical

terminology, anatomy and physiology and assessment criteria necessary for

successful completion of your learning progression. There will additionally be 3

half day study sessions which will include the A+P of the eye, evidence based

ophthalmic care, case scenarios, transposing workshop, problem solving, quiz-

zes and opportunity to discuss your questions.


CLINICAL SKILLS COMPETENCIES LIST

1. Visual Acuity which includes LogMar, Snellen, Near Vision, Colour (Ishi-

hara), Sheridan Gardner and Kay Pictures.

2. Measuring Intra-ocular Pressure using the I-care device.

3. Humphrey Visual Fields.

4. Autorefraction.

5. Oculus Pentacam.

6. Optical Coherence Tomography (OCT): TopCon and Spectralis.

7. Focimetry (Lensometer).

8. Specular Microscopy (Endothelial Cell Count).


LIST OF SOME COMMON OPHTHALMIC TERMS

ACCOMMODATION:

The process by which the ciliary muscles inside the eye contract or relax

to increase the refractive power of the eye’s natural lens.

AFFERENT PUPILLARY DEFECT:

A failure of a nerve pathway from one of the eyes to transmit a message

to the brain.

AMBLYOPIC EYE:

A normal eye that doesn’t see clearly even with spectacles, often caused

by inadequately treated squint.

ASTIGMATISM:

An irregular shape to the front of the cornea which, without spectacle

correction, may cause a varying degree of visual distortion.

CATARACT:

Opacity of the normally transparent lens.

DIABETIC RETINOPATHY:

Changes in the visible characteristics of the blood vessels of the retina.

DIPLOPIA:

Double vision.


ECTROPIAN:

A condition where the lower eyelid is ‘loose’ and so cannot make good

contact with the eye.

ENTROPIAN:

A condition where the lower eyelid is ‘tight’ and may roll inwards causing

the eyelashes to scrape the cornea.

FLOATERS:

Debris in the vitreous.

GLAUCOMA:

An umbrella term for a number of eye conditions that are often, but not

invariably associated with raised intra-ocular pressure.

HYPERMETROPIA:

Long-sightedness, where a person’s distant vision is better than their

near vision due to a shorter than average eyeball.

HYPHAEMA:

Blood in the anterior chamber of the eye.

HYPOPYON:

A mass of white inflammatory cells in the anterior chamber of the eye.


INTRA-OCULAR PRESSURE:

The hydrostatic pressure inside the eye.

LAZY EYE:

A normal eye which at some stage was misaligned. The brain never re-

ceived a clear image on this side and visual perception via the optic

nerves and brain did not develop as well as it might have done.

MACULAR OEDEMA:

An accumulation of fluid within the retina at the macular area.

MONOCULAR DIPLOPIA:

Double vision perceived by only one eye.

MYOPIA:

Shortsightedness, where a person’s near vision is better than their dis-

tant vision.

PAPILLOEDEMA:

A swollen optic disc with blurred edges and dilated superficial capillaries.

PHOTOPHOBIA:

Light sensitivity.

PINGUECULA:

Small round yellow looking lumps that appear on the conjunctiva on ei-

ther side of the cornea. They are the result of conjunctival degeneration.

They are benign.


PRESBYOPIA:

Loss of accommodation in the lens due to aging.

PROPTOSIS:

Protrusion of one or both eyes.

PTERYGIUM:

Superficial fleshy looking, vascular wing of conjunctiva which slowly ex-

tends onto the cornea, and may eventually cover the pupillary area.

PTOSIS:

A condition when the affected upper eyelid or eyelids hang in a lower po-

sition than normal, which may affect vision.

SCOTOMA:

Blind spot.

TRICHIASIS:

Eyelashes which grow unevenly, usually in response to chronic eyelid in-

flammation.

Reference:

Field, D, Tillotson, J. and E. Whittingham. 2015. Eye Emergencies: The

practitioner’s guide. 2nd Ed. Keswick: M&K Update Ltd.


VISUAL ACUITY


1. Visual Acuity

All healthcare professionals working in the ophthalmic outpatients and acci-

dent and emergency departments are expected to perform visual acuity test-

ing. It is the initial procedure when examining the patient in order to assess

and obtain an objective visual function baseline measurement (Bailey and Lov-

ie-Kitchin 2013). Visual acuity testing has to be performed every time the pa-

tient attends our departments, even if the patient has a follow up review visit

on a daily basis. There are a number a reasons why visual acuity testing is im-

portant. One of the reasons is that it helps in the process of accurate diagnosis

for the patient (Marsden 2007). It also helps to assess progress or deteriora-

tion. It is not always a legal requirement (Field, Tillotson and Whittingham

2015), but it useful if a patient were ever to try and make a claim against you.

Basic Equipment

Snellen or LogMAR test chart

Sheridan Gardiner test chart

Pinhole occluder

Patient’s medical records

Tissues and hand gel/ hard surface disinfectant according to Trust policy

The Snellen chart

The Snellen chart is still presently being used, so it is important that you learn

this skill. The chart displays standard letters deceasing in sizes. This provides a

well-recognized measurement of central visual acuity. The letters are num-

bered from 60 at the top, down to 4 or 5 at the bottom, and are printed in


black on white background. The chart needs to be well lit for testing purposes.

Some Snellen charts come in different sizes, so please be careful to check the

size of the chart that you have so that you document accurately in the pa-

tients’ medical notes. The full-sized chart is designed to be read at a distance

of 6 meters, however, in a small clinical room this can be doubled by using an

appropriate mirror at 3 meters. Some charts are reduced in size, for example

the back assessment and treatment room in A+E which have to be read and

documented at 3 meters.

Procedure

Ideally the test should be carried out in a private area, unfortunately this is not

always possible due to the current environmental constraints and work capaci-

ty. Visual acuity at present is being performed in corridors and sub waiting

rooms which is not ideal. Please try and reduce surrounding noise levels when

possible and ensure the patient does not get distracted, interrupted or embar-

rassed. (This can be a challenge!)

Introduce yourself and check the identity of the patient against the medical

notes and explain the procedure. Position the patient so that they are com-

fortable at a distance of 6 meters away from the chart. Please make a note if

they are wearing contact lenses and make sure that they are wearing the cor-

rect distance spectacles (bifocals, varifocals and distance). If the patient is con-

fused about ‘glasses’ then ask them whether they wear glasses for television or

driving, this will give you an indication if they need refractive correction for dis-

tance.

Ask the patient to cover their eye one at a time using a disinfected occluder as

shown in diagram below. Now ask the patient to read the consecutive lines of

letters from the Snellen chart diminishing in size using each eye in turn. Ensure

that each eye is properly covered throughout the test of the other eye. Write

the result in the patient’s medical records.


The result for a person with average or corrected eyesight is usually 6/6 (Field,

Tillotson, and Whittingham 2015).

Explanation of 6/6 Snellen vision and other recordings:

The 6 at the top of the fraction is the number of meters the patient is sitting

away from the chart. The bottom 6 is the size of the letters the person with

average sight would be able to see when six meters away from the chart. If you

have a patient who has myopia and they did not bring their spectacles; the pa-

tient may only be able to see the first few letters (two lines) at the very top.

This has to be recorded as 6/36. The top figure 6 is because the patient is six

meters away from the chart, however the bottom figure is 36. This is because

the patient is only able to see what the average person with 6/6 vision would

be able to see from a distance of 36 meters away from the chart. Each line on

the chart is labelled with a tiny number underneath to indicate the distance at

which the letters can be read by an average-sighted person.

If the patient cannot read the top letter on the Snellen chart (6/60), the patient

will need to walk towards the chart 1 meter at a time until the largest letter is

seen with the tested eye. The vision is recorded at the distance from which the

largest letter is seen, for example 2/60= 2m from the Snellen chart.


If the patient cannot see to read the letters on the Snellen chart after trying

the above, the patient is asked to count the number of fingers held up by the

health professional at varying distances less than 1 meter.

If the patient is unable to count fingers, the next step is to wave hand move-

ments in front of the affected eye.

If hand movements is not achieved, a light from a torch is shone toward the

affected eye from four directions of a quadrant. This would be recorded as

Perception of light (PL).

If they cannot achieve PL then No Perception of light is recorded (NPL).

Pinhole

If the patient can identify letters from the Snellen chart but does not achieve

6/6, then the patient should be tested with the pinhole occluder, see below for

diagram showing how pinhole works:

Diagram image taken from google image (2016)


The patient is asked to repeat the visual acuity procedure with the pinhole oc-

cluder in front of the affected eye at a distance of 6 meters only (the unaffect-

ed eye is occluded at the same time). The structure and function of the retina

is organized in such a way that fine visual acuity is produced in the central

macular area. The use of the pinhole occluder reduces the peripheral rays of

light going through the pupil area. It allows only a narrow bundle of rays to en-

ter along the optical axis. It thus enables an assessment of central vision (Nor-

ton, Corliss and Bailey 2002).

The results of the Snellen Visual Acuity Test should be recorded in the patient’s

medical notes as the following examples below:

Right Visual Acuity (RVA) Left Visual Acuity (LVA)

6/18 with glasses (gls) CF’s

6/9 with gls and pinhole (ph) no improvement


6/6 with contact lenses (cls) 6/5


6/9 unaided (ua) 6/6

6/6 with ph -


6/24 with cls 6/6

6/12-1 with cls +ph -


Sometimes the patient is only wearing one contact lens in one eye but not in

the other, record as follows:


6/6 with c/lens 6/6 ua

If the patient has a dilated pupil, the lens in the eye may be less able to ac-

commodate and the vision may be reduced. Please use the pinhole and make a

note of this in the patient’s medical records.

You will come across patients who have an amblyopic eye (see terminology

p6). When you do please document in the notes (patient says lazy eye). At the

end of the procedure please disinfect the occluder according to Trust policy.

Another key point is if you come across a patient with a corrected vision of less

than 6/12, you must ask the patient if they are driving and document in their

medical notes. If this is the case, then they need to be informed that their eye-

sight may not reach the driving standard (DVLA 2015).

Please always when you document to sign and date the recordings.

Abbreviations used for recording vision:

PH - Pinhole

VA - Visual Acuity

CF - Count Fingers

HM - Hand Movements

PL - Perception of Light

NPL - No Perception of Light

Gls - Glasses


UA - Unaided (vision tested without glasses)

AE - Artificial Eye

CL - Contact Lenses

SG – Sheridan-Gardner

The LogMAR chart (logarithm of the minimum angle of resolution)

LogMAR is an algorithm for the logarithm of the minimum angle of resolution

(MAR). This distant visual acuity test is expressed using the logarithmic value,

meaning the smaller the letters on the chart, and the further away they are,

the smaller the value of the logMAR score associated with it (Field, Tillotson

and Whittingham 2015).


LogMar charts are designed to be used at 4m distance (Bailey and Lovie -

Kitchin 2013), however, for the moment we are using them at 2m distance.

This is because of restricted space in our working environment, the calculation

scores have therefore been carefully adjusted (see the logMAR laminated

guide table that is situated on the designated walls).

This distance visual acuity test is considered to be more accurate than Snellen

(Kaiser 2009). This is because each line has 5 letters and the letters are more

crowded together therefore, the patient will have more opportunity to read

letters from a line that they would otherwise miss on a Snellen chart. The test

is used mainly in macular degeneration and diabetic clinics as the scores may

help to detect subtle changes in vision (Field, Tillotson and Whittingham 2015).

Procedure

The procedure and preparation is similar to that of Snellen (see Snellen proce-

dure). Prepare environment, ensuring the correct alignment and position the

chart at 2m. The patient is encouraged to read along the line with one eye oc-

cluded, the letters starting with the larger ones at the top of the chart and

working their way down. Routinely we always start with the right eye.

If the patient is unable to read the top letters of the line at 2m, then move the

chart to 1m distance.

If the patient is unable to read the letters at 1m distance, then proceed with

CF, HM, POL, NPOL, AE and record in patient’s medical notes.

Use pinhole occluder like you would when testing Snellen visual acuity.

Repeat the process for the other eye.

How it works:

Each line will give a score of 0.1 less than the line above.


Each letter in each line has a digit score of 0.02.

How to document:

Document the logMAR score and please also document the Snellen equivalent

below.

If the patient can read all of line 0.3 with both eyes with glasses but unable to

read further with pinhole, then you would document 0.3 (see example below).


0.3 logMAR gls 0.3

No imp (improvement) gls + PH No imp

6/12 Snellen gls 6/12

If the patient can read three letters on line 0.9 with the right eye and 0.0 with

left eye, and right eye improving to 0.8, then you would document:


0.94 logMAR ua 0.0

0.8 PH -

6/48-2 Snellen 6/6

6/38 PH -

The 0.94 is documented for the following reason. Because each digit is equiva-

lent to 0.02 and the patient could only see 3 letters out of a possible of 5 on

line 0.9 that means 2 letters not read is documented as 4. One letter not read

would be documented 2.


See below the score equivalent chart (taken from google images).


The Sheridan Gardiner test

This test is used for patients who have communication difficulties such as

learning difficulties, non-English speaking and for children who can recognize

letters by shape but are unable to verbally articulate them (Field, Tillotson and

Whittingham 2015). The test consists of a pack of single letter cards and a sep-

arate larger card for the patient displayed with 7 letters. The letters are similar

shaped to that of Snellen but does differ slightly, so do document that the

Sheridan-Gardner test was used.

Procedure

Prepare the patient and environment as you would when performing Snellen

and logMAR.

Stand 6 meters away from patient, holding the cards, but displaying one card

at a time and starting with the larger letter first. The patient is sitting holding

the card with the 7 displayed letters, one eye is occluded.

The patient is asked to point to the corresponding letter displayed on their

chart. The patient needs a carer or health professional assisting to check eye is

occluded and to confirm that they have chosen the correct letter.


Repeat with other eye.

If the patient is unable to achieve 6/60, move forward one meter at a time and

document how you would using the Snellen chart. When possible try pinhole

occluder if vision less than 6/6. See example below:


6/9 SG ua 6/6

6/6 PH -

Reference:

Bailey, I. L. and J. E. Lovie-Kitchin. 2013. Visual acuity testing. From the labora-

tory to the clinic. Vision Research. 90: 2–9.

DVLA 2015. Visual Disorders. Medical Rules. London: DVLA.

https://www.gov.uk/driving-eyesight-rules [accessed 4-1-16]

Field, D, Tillotson, J. and E. Whittingham. 2015. Eye Emergencies: The practi-

tioner’s guide. 2nd Ed. Keswick: M&K Update Ltd.

Kaiser, P.K. 2009. Evaluation of Visual Acuity Assessment: A Comparison of

Snellen Versus ETDRS Charts in Clinical Practice. Transactions of the American

Ophthalmological Society. 107: 311-324.

Marsden, J. 2007. An Evidence Base for Ophthalmic Nursing Practice. Chiches-

ter: John Wiley & Sons.

Norton, T.T., Corliss, D.A. and J.E. Bailey, J.E. 2002. Psychophysical Measure-

ment of Visual Function. MA: Butterworth-Heinemann.

Images are taken from selection of authors own photography and from google

images 2016.

https://www.gov.uk/driving-eyesight-rules


Formative/Practice Assessment of Clinical Skills Competence

It is important that the student has had the time and opportunity to learn,

practice and reflect on any issues with the clinical skill before it is assessed

formally.

VISUAL ACUITY TESTING

Meeting with assessor:

Date:

Feedback comments in preparation for

Summative Assessment:


Summative Assessment of Clinical Skills Competence

VISUAL ACUITY TESTING

Standards Assessor’s comments to demonstrate

standard met

Knowledge required relating to the skill

Define visual acuity.

Analyze the normal physiology of vision

and explain the altered anato-

my/physiology (with reference to myo-

pia, presbyopia, hyperopia and astigma-

tism).

Explain and indicate the reasons for us-

ing different test types (logMAR, Snellen

and Sheridan-Gardner).


Reflect on the possible difficulties that

can arise when performing visual acuity

(for example: eye level, head tilting,

problems with noise distraction, cheat-

ing, communication, etc.) and discuss

problem-solving the issues.

Identifies the compassion and care

needs of our diverse population (cultur-

al, gender, age, etc.)

State the legal visual requirement for

driving and discuss your responsibilities

with reference to the DVLA, your role

and accurate documentation in medical

records.

Explain the importance of self-

monitoring of own personal professional

development.

Demonstration and practice descriptor


Prepare environment and individual

and ensure appropriate VA testing

charts/equipment, patient’s medical

records available.

Introduces themselves, obtains verbal

consent from patient/carer and ex-

plains procedure.

To be able to test and record visual

acuity for patients with all levels of

acuity (for example, count fingers,

hand movements, POL, NPOL.)

Demonstrate ability to assess and

record visual acuity on children, non-

English speaking, non-verbal, learning

disability patients using Sheridan-

Gardner method or other. (Communi-

cation skills).

Test and record visual acuity using

the pinhole occlude.

Demonstrate using conversion tables

to record visual acuity (logMAR. Snel-

len, metric).

Infection control is maintained.


Document results accurately in pa-

tient’s medical notes and ensures cor-

rect handling of medical notes (data

protection, confidentiality of health

information)

-------------------------------------- ------------------------------------

Date and signature of Student and Assessor

Confirmation of the skill achieved at the required level

N.B. Once the clinical skill has been achieved it is the student’s professional re-sponsibility to maintain the skill to that level of achievement or greater.


2. Measuring Intra-ocular Pressure using the I-Care tonometer

Anatomy and Physiology:

Intra-ocular pressure (IOP) is maintained both from the anterior (aqueous)

chamber and the posterior (vitreous) chamber inside the eye (Marieb 2012).

To understand the physiology of IOP, it is important to study the drainage sys-

tem of the eye.

The anterior chamber contains aqueous fluid. Aqueous fluid is clear and pro-

duced by the non-pigmented portion of the ciliary processes through active se-

cretion, ultrafiltration and diffusion. It contains water with electrolytes, glu-

cose, amino acids, ascorbic acid and dissolved gases. The function of aqueous

is to provide nourishment for the posterior cornea and lens as well as mainte-

nance of the shape of the eyeball (Marsden 2007).

The posterior (vitreous) chamber, posterior to the lens contains a gel like sub-

stance called vitreous humor. Vitreous humor is a clear, avascular, gelatinous

body made up of 99% water and 1% collagen and hyaluronic acid molecules.

The function of the vitreous humor is to prevent the eyeball from collapsing

inward by reinforcing it internally (Marieb 2012).

The physiology of intra-ocular pressure equation is:

IOP = F/C + PV

F = aqueous fluid formation rate

C = outflow rate

PV = episcleral venous pressure


In other words, there are 3 main factors that determine the level of IOP. They

are:

1. The rate of aqueous secretion by the ciliary processes.

2. The resistance encountered by the drainage of aqueous through the tra-

becular meshwork.

3. The level of episcleral venous pressure

IOP can be influenced by time of day, heartbeat, respiration, blood pressure,

age, sleep, exercise, race, corneal thickness, refractive error, drugs, caffeine

and alcohol (Marsden 2007). Average IOP measurements are between 10 – 21

mm Hg (Field, Tillotson and Whittingham 2015).

See below for basic diagrams of the drainage system of the eye (colour image

taken from google 2016):


Nearly all patients (especially new patients) that attend our departments will

need IOP measurement. Please be aware, that patients who are seen in the

glaucoma clinic will have to have their IOP measured using Goldmann applana-

tion tonometry by an ophthalmic nurse or doctor. This is because of local poli-

cy and the request of glaucoma consultant.

Intra-ocular pressure is measured in millimeters of mercury (mmHg)

Procedure

Prepare environment and ensure equipment device in working order (icare to-

nometer needs to be charged and have the appropriate disposable probes).

There are icare tonometry manuals on how to use in clinical room 3 for infor-

mation and guidance. You can use the same probe for both eyes, but if the pa-

tient has an eye infection and IOP still required than ensure you start with the

affected eye, then dispose probe and insert a new probe for the other eye.

Please refer to local Trust infection control measures.

The icare tonometer does not require anaesthetic eye drops or calibration.

Please note that if the icare tonometer is not used for three minutes, the to-

nometer will automatically switch off.


Explain procedure to patient and obtain verbal

consent. This is to appropriate the needs of indi-

vidual patient and to gain reassurance and co-

operation. It does help talking to the patient

while you are executing the skill and explaining

what sensation they may feel (sometimes it has

been described as a stroke of a feather).

Step by step guide on turning the to-nometer and load-ing the probe:

1. Press main button

2. Go to measure and

press the main button

3. Partially open the

probe package

4. Insert the probe into

the tonometer from

the partially opened

package without

touching the probe

5. Gently press the

probe into the probe

base to lock the probe

(be gentle not to bend

the probe)

6. Press the main button

once to activate the

inserted probe


Measurement

1. Select eye (OD=RE, OS=LE)

using the navigation buttons

2. Position tonometer near pa-

tient’s eye at an angle of 90

degrees

3. The distance from the tip of

the probe to cornea must be

approx. 3-7mm. if necessary

adjust the distance using the

forehead support

4. Press the main button lightly

to perform one individual

measurement, taking care

not to shake the tonometer.

The tip of the probe should

make contact with the cen-

tral cornea

5. Make 6 single measurements

6. Once 6 single measurements

are taken, the final IOP is

displayed. Save the meas-

urement result by pressing

main button after results


Taking 6 single measurements eliminates the variations caused by operator er-

ror.

Once you have the IOP results, document carefully in patient’s medical notes

as follows:

RE LE

16 T 18 using icare

Reference:



Marieb, E. N. 2012. Essentials of Human Anatomy and Physiology. 10th Ed. Lon-

don: Pearson Education.

Marsden, J. 2007. An Evidence Base for Ophthalmic Nursing Practice. Chiches-

ter: John Wiley & Sons.

Images taken from google images and authors own.





formally.

MEASURING INTRA-OCULAR PRESSURE USING ICARE


Date:





MEASURING INTRA-OCULAR PRESSURE USING ICARE


standard met


Define intra-ocular pressure.


Analyze the normal and altered anat-

omy and physiology of the drainage

system of the eye (include aqueous,

anterior, posterior chamber and cor-

nea, raised IOP).

Explain the process of IOP measure-

ment and importance of patient co-

operation

Reflect on the possible difficulties

that can arise when performing IOP

(for example: eye movement, prob-

lems with noise distraction, commu-

nication, tonometer error, etc.) and

discuss problem-solving the issues.

Differentiate between the various

methods available to measure intra-

ocular pressure in order to rationalize

the right method for any particular

patient (note glaucoma clinic).

Appraise the advice and action you

would seek should any complication

occur (for example, device error, high

measurement readings).

Discuss your role and responsibilities

with reference to the above and your

legal position as an ophthalmic tech-

nician.




and ensure equipment is ready for

procedure.

Introduce themselves and confirms

identity of patient, explains proce-

dure.

Obtains verbal consent from pa-

tient/carer.

Demonstrates communication skills

when executing skill (with non-English

speaking and learning disability pa-

tients).

To be able to execute the skill meas-

uring intra-ocular pressure (ensuring

6 individual measurements taken and

accuracy)


Demonstrates correct use of icare to-

nometer

Infection control is maintained.

Document results accurately in pa-

tient’s medical notes and ensures cor-



information)

-------------------------------------- ------------------------------------





3. Humphrey Visual Fields

Visual field testing measures the full horizontal and vertical range and sensitivi-

ty of your vision. The machine we use for testing this is the ‘Humphrey Visual

Fields Analyzer’.

VISUAL FIELDS TESTING


The Humphrey Visual Fields Analyzer is used to detect scotoma (blind spots)

which offer important clues about the presence and severity of diseases of the

eye, optic nerve and visual structures in the brain (Field, Tillotson, and Whit-

tingham 2015).

There are many eye and brain disorders both acute and chronic that can cause

loss of peripheral vision and other visual field abnormalities. Glaucoma is one

of them and is known to create a very specific visual field defect (Field, Tillot-

son, and Whittingham 2015).

Humphrey visual field testing (HFT) is performed on a daily basis. We have

separate HFT clinics and we accommodate patients referred from A+E, general

clinics and wards.

What is glaucoma?

Glaucoma is a group of eye conditions which causes optic nerve damage and

affects your vision (Royal National Institute of Blind People (RNIB), 2016). It can

be caused by raised intra-ocular pressure and/or weakness in the optic nerve

(see pages 29-30 to recap on the A+P of the drainage system of the eye).

There are four main types of glaucoma. They are Primary open angle glaucoma

(POAG), Acute angle closure glaucoma, Secondary glaucoma and Developmen-

tal glaucoma. See images below for illustration of HFT fields results on patient

with right eye normal and left eye advance loss of visual fields and diagram

showing optic disc cupping.


————————————————————

The three most common reasons for using Humphrey fields test:

1. To monitor glaucoma.

2. Test for brain injury/stroke.

3. Test for Ptosis - Ptosis is the drooping of the eyelids.

The clinical skill competency required for Humphrey Visual Field Analysis re-

lates to the ability to carry out the test in an accurate manner. To master this

skill competency, you will need time and practice. It is a good idea to have a go

at being ‘the patient’ and experience what the test entails. This will give a bet-

ter understanding of what is expected from them.

The testing parameter that we use is Central 24-2 Threshold Test. This test has

54 test points. It is faster and reduces trial lens artifact errors. Do check in pa-

tients’ medical notes what fields test is required as you may need to perform

more specific tests such as Ptosis and binocular Esterman field (a test require-

ment for the DVLA).

The procedure


Introduce yourself to the patient, check the identity of the patient, explain the

procedure and gain consent. If new patient, please explain procedure can take

up to 8 minutes for each eye.

Clean the working environment and equipment (chin rest and forehead bar

and eyepatch) according to infection control local policy.

Position the patient as comfortable as possible to promote cooperation and

promote privacy for confidentiality.

The patient is encouraged to keep their chin in the chin rest and forehead

against the forehead bar, (you will need to adjust the height of the table and

height of the chin rest so that the eye is in line with demarcation line on up-

right support).

The eye that is not being tested will need to be covered with an eye patch.

The patient must always look at the central fixation light.

Enter the details of the patient. Ensure the patient’s correct current prescrip-

tion and age is put in the Humphrey data. This is important because the ma-

chine needs to calculate the trial lenses. You may need to perform focimetry to

check prescription of glasses. If the patient forgot to bring their spectacles,

please auto-refract patient and use the auto refracted measurements. (There

may be a recent opticians prescription so do check in the patient’s medical

records).

Insert correct trial lens. These are sets of lenses of two types: sphere and cyl-

inder. Spherical lenses are plus and minus power. Cylinders may be plus, minus

or both. You will find trial lens cases in the fields’ room.


The patient’s spectacle prescription will be found in their medical notes and is

written in a format as illustrated below:

OD: - 2.00 – 1.50 a85 (right eye, minus sphere, minus cylinder and axis)

OS: -1.75 + 1.25 a95 (left eye, minus sphere, plus cylinder and axis)

More ophthalmic Latin abbreviations to learn:

OD means right eye oculus dexter

OS means left eye oculus sinister

OU means both eyes oculus uterque

Transposing

Some opticians prescribe eye glasses in what is called a plus cylinder and oth-

ers do so in minus cylinder - the actual prescription is the same. Transposing

the prescription is necessary if you only have plus (+) cylinder trial lenses avail-

able, for example at PRH.


How to transpose:

1. Add the sphere + cylinder powers to determine the new sphere power.

2. Change the sign of the cylinder.

3. Change the axis by 90 degrees.

Example illustrated below:

+ 3.00 - 2.00 x 30

+ 1.00 + 2.00 x 120

More examples in image below:

Ptosis test

If you are testing for Ptosis, you need to test on their superior field of vision

first (untaped). Then you repeat the test with the patient’s upper eyelid taped

up. This is referred to as lids lifted/ lids relaxed in our department but may be

referred to as “taped/untaped” elsewhere. If there is Ptosis only in one eye,

then only test the affected eye. No trial lens is required when performing Pto-

sis field test. If the tape does not hold, you can ask the patient to hold their lid

up

Please stay with patient during testing. It can be tiring for some patient’s.

Please monitor patient ensuring correct eye level, encourage the patient and

maintain positivity. Having a positive attitude does provide optimal results.

When one eye is completed, save the data, and proceed with the other eye.

Re-explain if needed. When both eyes completed, save the data and print. File


printed results into patient’s medical notes. Record accurately in the patient’s

notes detailing what test, date and sign (document if test was problematic and

if they were wearing contact lenses).

At the end of the test show the patient to the clinic, or release but ask when

they are coming back. If the patient is new check the result of test with senior

member of staff before releasing.

The following should be monitored:

Fixation Loss - how many times the patient looks away from the central target.

This number should be less than 4.

False Positives - when the patient responds when no stimulus is present. This

tests the understanding of the test.

False Negatives - when the patient at first responds to a dim light, but later in

the test does not respond to a brighter light in that same location. The purpose

of false negatives is to test the patient’s alertness.

Stimulus Brightness - this represents how bright a stimulus had to be before

the patient would see it. A number of 0 represents no vision in that area. The

larger the number the better.


Reference:



Royal National Institute of Blind People. 2016. Glaucoma. London: RNIB.

images taken from google 2016.





formally.



Date:







standard met


Define visual fields.


omy and physiology of the eye (in-

clude eye condition glaucoma).

Explain the process of the test proce-

dure and the preparation



that can arise when performing this

test (for example: eye movement,

problems with noise distraction,

communication, incorrect trial lens,

alertness of patient, etc.) and discuss

problem-solving the issues.

Differentiate between the various

HFT test programs available (for ex-

ample, 24-2. Esterman, Ptosis)



occur (for example, printer not print-

ing, abnormal or unusual results dis-

played, patient trigger happy).




nician.




and ensure the Humphrey machine is

in full working order.



dure.


tient/carer.

Identifies any cultural and special

needs that may influence perfor-

mance of test.

Develop strategies to overcome com-

plex communication issues to be ef-

fective with both patient and staff

alike.

Ensures appropriate field to suit oph-

thalmic concerns

Confirms patients existing use of opti-

cal aids and ensure correct trial lens is

used.

Position and align patient correctly

for test and monitor during test pro-

cedure

Maintains correct infection control

measures as stipulated by local Trust

policy


Recognizes common patterns of arte-

factual test results and reliability indi-

ces.

Files and document results accurately

in patient’s medical notes (signature,

date and test type and ensures cor-



information)

-------------------------------------- ------------------------------------





4. Auto-refraction

The auto-refractor is a computer controlled machine. It is sometimes used as

part of an eye examination to provide an objective measurement of a person’s

refractive error and prescription for glasses/contact lenses. It is routinely per-

formed in the post-op cataract clinic and when requested by an ophthalmolo-

gist. Auto-refraction is achieved by measuring how light is changed as it enters

the patient’s eye (Wolffsohn et al, 2011). The procedure is quick, simple and

painless. Auto-refraction is particularly useful to perform on patients’ who are

non-communicative such as young children.


The procedure

Prepare the environment. Ensure auto-refractor in working order, the chair has

the functioning height adjustment for the patient and that equipment has

been cleaned according to local infection control policy.

Introduce yourself to the patient, check identity of the patient and explain pro-

cedure, gaining verbal consent and cooperation.

Wipe the auto-refractor’s chin and head rest. Ask the patient to take a seat.

Turn the auto-refractor machine on and ask the patient to place their chin on

the chin rest and forehead against the bar. They must remove their glasses for

this test. Meanwhile you are adjusting the height of chin rest and head bar so

that the testing eye is level and correctly aligned.

One eye at a time, the patient looks at a picture (colourful hot air balloon at

the end of a long path).

Explain to the patient that the image of balloon will go in and out of focus (re-

assure). As the image goes in and out of focus the machine takes readings to

determine when the image of the hot air balloon is on the retina. Several read-

ings are taken automatically which the machine averages to form a prescrip-

tion/refractive error.


The patient does not need to feedback during the process.

The patient does not need to have one eye occluded and it does not matter if

the eye is dilated.

Within seconds an approximate measurement of the patient’s prescription can

be made by the machine and printed out if necessary (ensure you have correct

roll paper).


Once procedure is completed, place the print out in patient’s medical notes.

Reference:

Wolffsohn, J.S. et al. 2011. Evaluation of an open-field autorefractor’s ability to measure refraction and hence potential to assess objective accommodation in pseudophakes. British Journal of ophthalmology. 95: 498-501.




formally.

AUTO-REFRACTION



Date:




AUTO-REFRACTION



standard met


Define auto-refraction.



clude refractive errors such as myo-

pia).


dure and the preparation.

Have an applied knowledge of manual

handling.





communication, astigmatism, high

myopia) and discuss problem-solving

the issues.



occur (for example, inability to obtain

readings, printer not printing, paper

jam, and incorrect roll paper).




nician.




and ensure the Auto-refractor is in

full working order.



dure.


tient/carer.




alike.


for test ensuring patient is comforta-

ble



policy

Demonstrates understanding of parts

and functions of the Auto-refractor

and that regular maintenance check

has to be carried out




date and ensures correct handling of

medical notes (data protection, con-

fidentiality of health information)

-------------------------------------- ------------------------------------





5. Oculus Pentacam

Oculus Pentacam is an ophthalmic computing machine. It is the Gold Standard

in Anterior Segment Topography. Topography is defined as the science of rep-

resenting the features of particular places in detail, in this case the cornea

(Ring and Okoro, 2012). There are three refractive elements of the eye, the ax-

ial length, lens and cornea. The cornea has the highest refractive power.

We use Oculus Pentacam to detect and assess for keratoconus. It is also used

for cross linking purposes, pre-surgical planning of refractive corneal surgery

and glaucoma screening.

Keratoconus definition:

Keratoconus is a slow, progressive eye disease in which the normally round,

dome shaped cornea thins and begins to bulge into a cone-like shape. This

cone shape is irregular, bending light as it enters the eye. The images entering

through the irregular Keratoconus corneal surface creates distortion and blur-

ring of the vision.


Procedure

Introduce yourself to the patient, check ID of the patient and explain the pro-

cedure. You want to promote the patient’s understanding in order to gain co-

operation, obtain consent and allay anxiety.

Turn on the PC that is attached to the Oculus Pentacam, the printer and the

Pentacam itself, this is to ensure you save and store the patient’s measure-

ments.

Equipment should be cleaned according to infection control local policy to re-

duce the risk of cross infection. (The forehead and chin support and table)

Double click on the Pentacam logo with the computer mouse to access Patient

ID input screen. Enter patient details and click save data. Confirm whether this

is a new episode for a new patient or a further episode for known patient.

Ensure that the patient is not wearing glasses or contact lenses. Position the

patient comfortably at the appropriate height with medial canthus meeting the

marker on the side of the chin rest/forehead apparatus ensuring privacy within

the examination area to promote cooperation and confidentiality.


Click on ‘examination’ and click ‘scan’ from the drop down box. Ask the patient

to look directly ahead at the blue slit light with the eye to be measured ensur-

ing good fixation for accurate scans to be obtained.

Using the joy stick ensure the blue light is in the middle of the selected cornea,

then move forward slowly until the lids and cornea can be seen in the main

screen. Observe the target screen, centralize the cornea until the three straight

lines become sharp and the yellow cross is centred in the target.

Inform the patient to stare at the blue light with wide open eyes and try not to

blink. Advance slowly until the red dot on the cornea almost meets the line.

Instruct the patient to take a long blink and then open their eyes very wide.

The Pentacam should now automatically take the scan when the optimum po-

sition is achieved. Do try and encourage the patient to keep their eyes wide

open during the seconds that the scan is being taken.

If the patient is suffering from a dry tear film, then ask the patient to blink pro-

fusely a few times or instill lubricating eye drops. Having a moist cornea does

promote better quality scans/images.

Once the Pentacam has taken the scan, advice the patient to sit back. Evaluate

the images. If the comments on the Pentacam display inadequate such as blink

or red and yellow highlighted K’s, then repeat the process.

Once scan results display appropriate quality, click to print. Insert scan results

in patient’s medical records.

Reference:

Ring, L. and M. Okoro. 2012. A Handbook of Ophthalmic Nursing Standards &

Procedures. Keswick: M&K Publishing.





formally.

OCULUS PENTACAM


Date:





OCULUS PENTACAM


standard met


Define Oculus Pentacam.



clude the cornea and keratoconus).





handling.




communication and dry tear film) and





readings, printer not printing, paper

jam, and incorrect roll paper).




nician.




and ensure the Pentacam, computer

and printer is in full working order.

Working environment is free from

hazards and the patient is safe (Not

wearing any glasses/contact lenses).



dure.


tient/carer.




alike.



ble



policy



and functions of the Pentacam and

that regular maintenance check has

to be carried out






-------------------------------------- ------------------------------------



N.B. Once the clinical skill has been achieved it is the student’s professional re-

sponsibility to maintain the skill to that level of achievement or greater.


6. Optical Coherence Tomography

Optical Coherence Tomography (OCT) is a non-invasive imaging test that uses

light waves to take cross-section images of your retina, macula and optic disc

(Boyd and McKinney, 2015). These images help with diagnosis and provide

treatment guidance for glaucoma and retinal diseases, such as age-related

macular degeneration and diabetic eye disease. The Coherence in OCT refers

to the physical characteristics of light which allow interference patterns to

form. The computer program facilitates the production of the cross section im-

age.

All patients requiring OCT will have an accurate reading so that that the oph-

thalmologists can diagnose and review to inform patient of treatment options

or disease progression. OCT is performed on a daily basis and the clinic can be

busy, challenging and oversubscribed. In order to perform OCT it is useful to

have an understanding of the various retinal diseases.

Age-Related Macular Degeneration (ARMD)

ARMD is a progressive chronic disease of the central retina and a leading cause

of vision loss (Lim et al., 2012). There are 2 types of ARMD.


1. ‘Wet’ ARMD

In ‘wet’ neovascular age-related macular degeneration, choroidal neovascular-

ization breaks through to the neural retina, leaking fluids, lipids, and blood,

leading to fibrous scarring.

2. ‘Dry’ ARMD

In ‘dry’ geographic atrophy, progressive atrophy of the retina; pigment epithe-

lium, choriocapillaris and photoreceptors occurs.

Diabetic Eye Disease

Diabetic eye disease primarily affects the retina. Pathological damage to the

microvasculature leads to retinal ischaemia and proliferative retinopathy, but

macular oedema and maculopathy are the main causes of visual loss (Bilous

and Donnelly, 2010).

The procedure

The following steps should be completed:

Ensure the OCT (TopCon or Spectralis) machine is turned on and sit your pa-

tient in the examination chair. To ensure effective time management.

Introduce yourself to the patient, check patients’ ID and explain procedure. It

is beneficial to ask the patient to blink normally during the test until asked not

to blink. This explanation helps gain cooperation, obtains consent and calm

anxiety which in turn will bring better quality images.

Enter patient details as prompted by machine: Name, DOB. Hospital number.

This will link to any necessary print-out and storage of data unique to patient

identity.

Select the program to be used. For instance radial for macular assessment and

circle for optic disc assessment. This can be done by touching the OCT screen

device once patient’s details have been entered and confirmed.


Position the patient comfortably and reassure patient that although the ma-

chine will come close, it will not touch their eye. Ask the patient to focus on

the green fixation dot/cross (may be a blue dot on Spectralis machine).

Adjust and align the patient with the machine (height and chin rest) using both

the table machine and joystick so that the patient’s eye is correctly aligned

(aim for the lower third of the pupil).

Gently guide the scan head focusing through the pupil until image of retina can

be seen on the screen. The scan shape is seen on the fundus (flashing line, cir-

cle or asterisk depending on the scan chosen).

Observe the image on the left hand side of the screen and use the offset but-

tons to move image up or down if needed. Press optimize if image not appar-

ent.

Press scan button on machine to begin streaming allowing the images to be

produced.

While streaming ask the patient to continue blinking, but once clear image

seen ask the patient to hold their blink then take the image pressing appropri-

ate button (usually on joystick). This ensures images are captured to facilitate

analysis.

Repeat the process for the other eye.

Ask the patient to sit back and relax whilst analysis takes place.

Press and review the images. Select images to save, delete unnecessary imag-

es. Ensure you press F10 on computer keyboard to save on OIS so that the doc-

tors can view image on their computer screens.

Sign and date in the patient’s medical records to act in accordance with profes-

sional guidelines.


Reference:

Bilous, R. and R. Donnelly. 2010. Handbook of Diabetes. Oxford: Wiley-

Blackwell.

Boyd. K. and J. K. McKinney. 2015. What is Optical Coherence Tomography?

American Academy of Ophthalmology. www.aao.org/eye-health/.../what-is-

optical-coherence-tomography. [Accessed 6-5-2016].

Lim, L.S. et al. 2012. Age-related macular degeneration. The Lancet. 379

(9827): 1728-1738.




formally.

OPTICAL COHERENCE TOMOGRAPHY


Date:





OPTICAL COHERENCE TOMOGRAPHY


standard met


Define Optical Coherence Tomogra-

phy.



clude the optic disc and the macular).





handling.




communication and dry tear film) and





readings, printer not printing, and OIS

not saving and sending).




nician.




and ensure the OCT, computer and

printer is in full working order. Work-

ing environment is free from hazards

and the patient is safe (Not wearing

any glasses/contact lenses, eye dilat-

ed if necessary).



dure.


tient/carer.




alike.



ble



policy



and functions of the OCT.






-------------------------------------- ------------------------------------






7. Focimetry

Focimetry is a way of determining the power of a lens. Focimetry is also known

as a lensometer or vertometer. Focimetry can determine the spherical power,

cylindrical power, axis, prism and the position of the optical centre of a lens.

The focimeter is kept in the field’s room and is mainly used when you need the

patient’s prescription details when performing HFT or when otherwise re-

quested.

Image of focimeter with labelled parts:

1. Eye piece

2. Reticule adjustment

3. Prism compensator

4. Lens marker

5. Lens holder

6. Eyeglass table

7. Magnifier

8. Axis adjustment knob

9. Filter control

10. Inclination control (locking lever)

11. Power drum

12. Eyeglass table control


Procedure

Before you start, make sure the prism compensator is at 0 and that the eye-

piece is focused for your eye. To do this you need to keep the focimeter power

off. Rotate the eyepiece counter-clockwise until the reticle is blurred. A white

piece of paper held behind the eyepiece may make the reticle lines more visi-

ble. Turn the eyepiece clockwise until the reticle is just clear. The focimeter is

now adjusted for your eye (make sure you do not turn past the point at which

the reticle is first clear).

Step by step guide:

Turn the focimeter on

Turn the power wheel into the plus, then slowly de-

crease the power until the focimeter target is sharply

focused. Do not oscillate the wheel back and forth to

find the best focus. The power wheel should read 0 if

the instrument is in proper calibration.

If the power wheel does not read 0, re-focus the eye-

piece and re-check the calibration. If the power wheel

still does not read 0, the error must be compensated

for on all future measurements made with the foci-

meter, or maintenance is suggested.

Position the spectacles so that the front of the spec-

tacles is facing towards you. The spectacle arms

should be pointing away from you.

Put the spectacles on the frame table. The bottom

rim of the spectacles should rest on the frame table.

Starting with the right lens. Clamp the spectacle lens

to keep it pressed against the lens rest.


Look through the eyepiece and move the spectacles

side to side and up and down until the target is in the

centre of the black graticule.

Change the height of the frame table to keep the

frame horizontal in this position.

When the lens is positioned (where the centre of the

focimeter target is over the centre of the graticule)

then you are at the optical centre of the lens.

Mark the optical centre.

Determine the right lens power by turning the wheel

to a high plus reading.

Slowly decrease the power until the target lines just

become clear.

All the target lines will come into focus at the same

time.

Read the power drum to determine the spherical

power.

If the lens is astigmatic, only some of the lines are

clear at a given power.

For astigmatic lens turn the axis wheel until the three

parallel target lines are straight and unbroken.

The number on the power wheel at this point is the

most positive meridian of the lens. This will be the

spherical power when you write the astigmatic lens

prescription.

Slowly turn the power wheel to decrease the power

until the other line is clear. The number on the power

wheel will now tell you the power of the least posi-

tive meridian of the lens. See below the image


Find the cylindrical power of the lens. (this is the difference in

powers)

Find the axis of the cylinder (direction of the second power reading – the

least positive power) the direction of this line is measured by aligning

the graticule and looking at the axis numbers on the graticule inside the

eyepiece.

Now proceed with the left lens without changing the height of the lens

table.

There should be no need to move the lens up and down as the focimeter

target should be vertically aligned with the graticule at the table height

for the right lens.

Now determine the prism by keeping the lens table at the same height

on swapping from right to left lens.

If the focimeter target is not centred vertically about the reticule, then

there is vertical prism present

The size of the prism can be read from the reticle markings.

Horizontal prism is determined marking the optical centres of each lens.

Then determining the patient’s inter-papillary distance (IPD), mark the

left lens at the IPD distance away from the optical centre of the right

lens.


Clamp the left spectacle lens on the lens rest so that the PD mark that

you made on the lens is over the centre of the lens rest.

Measure the horizontal prism and direction using the reticule. This is the

total horizontal prism.

To determine the near add, turn the spectacles around (arms of specta-

cles point towards you) The near addition is a measure of the front ver-

tex power- as opposed to the distance prescription which is a measure

of back vertex power.

Measure the power of the distance section and compare this to the

power of the near section (the difference is the near addition).

For astigmatic lenses, simply compare one meridian in the distance to

the equivalent meridian in the near, again the difference is the near add.




formally.

FOCIMETRY



Date:




FOCIMETRY


standard met



Define Focimetry




handling.



test and discuss problem-solving the

issues.




readings, image lines not clear).




nician.



Prepare environment and ensure the

focimeter is in full working order.

Working environment is free from

hazards.


identity of patient and confirms spec-

tacles are theirs.

Position and align spectacles correctly

for test.



policy



and functions of the focimeter.






-------------------------------------- ------------------------------------






9. Specular Microscopy

The purpose of performing corneal endothelial cells count is for:

Cell count of a tissue

Quality of tissue

Shape variability (pleomorphism)

Size variability (polymegathism)

The reason why this test is requested is for determining the health of the en-

dothial cells. For example, it is important for the surgeon to know before cor-

neal transplant and cross linking, as a good cell count is essential. Another ex-

ample is determining the cause of corneal oedema and to develop an appro-


priate treatment plan. Therefore accurate measurement of endothelial cell

density is important.

To do this test it is recommended you have some prior knowledge of the A+P

of the cornea. The corneal endothelium is responsible for maintaining corneal

hydration (Bucht et al, 2011). Common ocular conditions, such as glaucoma,

uveitis and Fuchs endothelial dystrophy, may produce changes in the structure

and function of the corneal endothelium that result in corneal oedema and

visual impairment.

The way the test works is that light is projected onto the cornea and captures

the image that is reflected from the optical interface between the corneal en-

dothelium and the aqueous humour. Specular Microscopy machine is situated

in the OCT room. The procedure is a non-invasive photographic technique.

Procedure

Ensure specular machine is turned on and is in working order.

Introduce yourself to the patient and check their ID and explain the procedure

gaining verbal consent.

Enter patient’s details as prompted by machine.

Position the patient comfortably and reassure the patient.

Adjust and align the patient with the specular machine using both the table

and joystick.

Carefully move the joystick forward so that the beam of light is directed

through the pupil to ensure the placement of the cone is on the most central

portion of the cornea.

Systemic scanning superiorly, inferiorly, inferiorly, nasally, and temporally will

ensure a thorough evaluation of the endothelium.

Light reflexes from the iris can obscure the endothelial mosaic and are best

eliminated by dilating the pupil.


The image should be repeated 3 times at the same sitting and record the aver-

age of the three images analysis.

Use the same image analysis method from baseline and throughout the follow-

up period.

The most common errors seen are related to improper application of method

of analysis. There is a need to identify cell borders, boundaries, and centres.

Reference:

Bucht, C. et al. 2011. Simulation of specular microscopy images of corneal en-

dothelium, a tool for control of measurement errors. Acta Ophthalmologica.

89 (3): 242-250.




formally.

SPECULAR MICROSCOPY



Date:




SPECULAR MICROSCOPY


standard met



Define Specular Microscopy


omy and physiology of the cornea (in-

clude the layers and cells).




handling.



test and discuss problem-solving the

issues.




readings).





nician.


Prepare environment and ensure the

Specular machine is in full working

order. Working environment is free

from hazards.


identity of patient.


for test (the beam of light has to be at

the most central portion of the cor-

nea).



policy



and functions of the Specular ma-

chine.






-------------------------------------- ------------------------------------





OPHTHALMIC CLINICAL SKILLS COMPETENCIES FOR … · ophthalmic care, case scenarios, transposing...

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