Tono en Gonio

8/6/2019 Tono en Gonio

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About your upcoming exam

50 questions Multiple choice, four possible answers

All questions taken directly from lecture Lecture notes are available in the

optometrie section in the library and online

Similar in style to the last exam No embryology

No slides


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Lecture notes online

For those who dont have it, the URL is: http://virtmed.fg.hvu.nl/domeinen/opto

metrie/optometrie.html

The password is redeye


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About your upcoming examCOSM3

Questions per topic covered: Methods (direct and indirect examination

of the fundus, tonometry, gonioscopy): 5

Fundus Landmarks: 2

Congenital variations: 8-9

Optic Neuropathy: 13 Fundus Spots: 21-22

Total: 50


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About your upcoming examCOSMB

Questions per topic covered: DPAs: 15-16

Methods (direct and indirect examination

of the fundus, tonometry, gonioscopy): 5

Fundus Landmarks: 2

Normal fundus: 7-8 Congenital variations: 8

Optic Neuropathy: 12

Total: 50


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Tonometry


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Tonometry

One abbreviation that will be usedthroughout your career is IOP, whichstands for intraocular pressure

Get used to it


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Tonometry

Measures tension in eye The combined resistance of het oog (IOP)

and the tear film

The main reason we measure this isbecause high pressure is a key indicator

of glaucoma Pressure is elevated in most types ofglaucoma


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Tonometry

Pressure can also be high in cases ofocular inflammation

Uveitis

Perforating injuries to the globe mayresult in an abnormally low pressure

This is called hypotony


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Tonometry

Measured in mm Hg There are three ways to measure IOP

Manometry

Applanation

Indentation


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Tonometry

Manometry The most accurate method of determining

IOP

A needle connected to a column ofmercury is inserted into the eye

Not generally performed in clinical practice


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Tonometry

Applanation Based on the Imbert-Fick formula

IOP = force/area

This is the same formula used in physics

If one measure is kept constant, pressure

is directly related to the other variable The Goldmann tonometer is the one we

use, and the worldwide standard

Also using this theory is the Maklolov unit


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Tonometry

The Goldmann tonometer has aconstant area

The force required to flatten the cornea is

directly related to the IOP

The Maklokov tonometer applies a

constant force The area flattened is directly related to theIOP


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Tonometry

IndentationA constant force applied to the cornea

The cornea is pushed posteriorly

The IOP is related to the distance thecornea is pushed

Influenced by corneal rigidity Tends to be lower in high myopes, who havelarger eyes and therefore slightly softer corneas

Aqueous humor is forced from the eye

Subsequent readings will be lower


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Tonometry

Normal IOP The average IOP is 16 mm Hg

Normal IOP is anywhere from 6 to 21 mm

Hg

An eye with an IOP under 6 is consideredhypotonous

Look for a wound leak (do the Seidel test)


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Tonometry

Normal IOPAn eye with an IOP over 21 is referred to

as hypertensive

Most people with ocular hypertension do notdevelop glaucoma

What this means is that some people have

pressure which is higher than most others, butfor them this is normal

You should make sure of your diagnosis ofocular hypertension with your anamnese and

other tests


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Tonometry

Physical factors affecting IOP Pressure on Globe

Holding lids--some people just wont keep their

eyes open no matter what you say, so youhave to force them open

By doing this, you can inadvertently press onthe globe, giving a false high reading

Blepharospasm, or forceful blinking, can do thesame thing


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Tonometry

Physical factors affecting IOP Trauma/Inflammation

Damage to the trabecular meshwork will

prevent the proper drainage of aqueous fromthe eye

This happens in angle recession glaucoma

Uveitis

In the beginning of the condition, IOP is slightlylowered due to decreased aqueous production

In the later stages, IOP increases as a result of cells

and flare, clogging the trabecular meshwork


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Tonometry

Physical factors affecting IOP Medications

Steroids

Use of these over a long period of time causesin increase in IOP in about 1/3 of all people

Blood pressure medication

Beta blockers, alpha agonists, and carbonicanhydrase inhibitors can lower IOP

Marijuana/alcohol

The effect is gone when it leaves the body


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Tonometry

Physiological factors affecting IOP Diurnal variation

IOP is highest at around 10AM, and lowest in

the late avond Normal variation is 4mm Hg per day, but may

be twice that in glaucoma

If you suspect glaucoma in a patient with highpressure, get a morning reading

If still unsure, you can do a diurnal curve

Start in the morgen, and read IOP every 1-2uur


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Tonometry

Physiological factors affecting IOP Vascular integrity

In cases of hypoxia, there will be low IOP from

decreased aqueous production Since this occurs throughout the eye, there

may be nerve damage despite low IOP

Patient position for measurement IOP is 2-3 mm higher lying down

This is not a problem with current techniques


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Tonometry

Techniques Finger tensions (digital IOP)

Goldmann

Perkins

Non-contact

Pulsair Tonopen

Pneumotonometer

Maklakow Glaucotest


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Tonometry

Finger tensions (digital IOP) Not accurate

Should only be done when all other

methods are not possible

Lightly push on the closedeye

Compare each eye to the other

Rate whether soft, normal, or hard


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Tonometry

Goldmann applanation tonometry Is the gold standard because of its

accuracy and repeatability

The only method used to diagnose andtreat glaucoma

Used with the spleetlamp

There is also a hand-held version made bymany companies, including Perkins


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Tonometry

Goldmann applanation tonometry Uses a tip which has prisms inside

The tip is 7mm in diameter, but only 3.06mm

of the cornea is applanated (flattened) by thetip

The prisms split the image horizontally topermit a proper measurement

Each half of the image contains a semi-circle,which is called a mire

When the mires are aligned properly, you have

determined the IOP


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Tonometry

This is what the mires look like whenthe unit is properly aligned and the IOPreading is correct


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Tonometry

Procedure for Goldmann tonometry Disinfect tonometer tip

Soak in 3% peroxide solution (contact lens

solutions work well) for tien minutes and thenrinse with saline solution

Place tip in holder

Align 180 mark of tip with horizontal line If the patient has more than drie diopters of

corneal astigmatism, place the minus cylinder

axis along the red line of the tonometer


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Tonometry

Procedure for Goldmann tonometry Place a drop of anesthetic in het oog

Instill fluorescein

Switch to diffuse illumination of maximumintensity with the cobalt blauw filter

Observe cornea for staining

Start with the right oog

Pull spleetlamp back

Place illumination system at 60 temporally


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Tonometry

Procedure for Goldmann tonometry Set measuring drum at 10

Note: the drum has numbers 0-8 on it. These

stand for 0 through 80. There are four linesbetween each number. These correspond totwee mm Hg each.

The line by the number 1 is 10 mm Hg. Theline after that is 12mm Hg. If the reading isbetween the first and second lines after thenumber 1, this is a reading of 13 mm Hg.


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Tonometry

Procedure for Goldmann tonometry Place tip in position, directly facing the

patient

Have the patient look straight ahead Bring tip toward het oog, looking from

outside the spleetlamp

When the limbus has a blauw glow, lookthrough the eyepieces

Move spleetlamp forward until you see themires


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Tonometry

Procedure for Goldmann tonometryAdjust the mires until they are centered

Turn the drum until the mires are properly

aligned Remove tip

Check for staining again


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Tonometry

To properly align the mires vertically, movethe spleetlamp in the direction of the largermire. In the picture on the left, you would

lower the spleetlamp, and this would alignthe mires. In the picture on the right, youwould have to raise the instrument. To alignthe mires horizontally, move the spleetlampin the direction of the mires. So in thepicture on the right, you would have to movethe instrument to the right as well as up.


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Tonometry

To have a proper reading, the inside edges ofthe mires should touch. The picture on theleft requires you to increase the reading on

the power drum. The picture on the rightrequires a decrease in the reading. Thepicture in the center shows a tonometerwhere the power is correct.


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Tonometry

15

16

1 Oxybuprocaine 16 30

To properly record, you must document thetest used, the drop used, the IOP reading,the time it was done, the fact that you told

the patient not to rub their eyes, and if thelids were held. If multiple readings weretaken, write them all down and averagethem. The method we use here is below.

lidsheld


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Tonometry

If there is too much fluorescein, as in thepicture on the left, the mires will be too thickand you will get a false high reading

If there is not enough fluorescein, as in thepicture on the right, the mires will be too thinand you will get a false low reading


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Tonometry

If you are pushing too hard on the eye, as inthe picture on the right, you will havedistorted mires which will not move when youchange the reading drum

If you are not pushing hard enough, as in thepicture on the left, the mires will go in and

out of view


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Tonometry

Things to remember Alignment for excessive corneal cylinder

If a patient has an ocular pulse (also called

a hippus) then the reading will fluctuate Set the reading so that the center of this

movement will be where proper alignment is

If you must hold the lids, you must movethe spleetlamp and the power drum withyour other hand

Scarred corneas give distorted mires


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Tonometry

The hand-heldtonometer works thesame way as theGoldmann tonometer

The power wheel iscontrolled by yourthumb

You should also recordthe patients position


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Tonometry

Non-contact tonometry (NCT) Works by applanation (by air)

A puff of air flattens a fixed area of cornea

The air stops when the cornea is flattenedenough to allow a light to be reflected to areceiver

The amount of air needed is related to theIOP, and the machine displays the nummer

Must average drie readings per oog

OK for screening purposes

T


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Tonometry

air pulse

Monitoring

mirror system

Light source

Air pulse

Non-Contact Tonometer (NCT)

T t


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Tonometry

Non-contact tonometry procedure Disinfect chin & headrest

Demonstrate puff

Switch instrument to regular mode

Align patient comfortably

Patient closes eyes

Set and test safety lock

Pull instrument slightly back

Have patient open their eyes

T t


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Tonometry

Non-contact tonometry procedure Direct fixation

Align targets

Instrument may shoot automatically ormanually

Take drie readings and average

Documentation is the same as with theGoldmann

T t


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Tonometry

Keeler Pulsair non-contact tonometer We have one of these in the preclinic

Hand held

Portable

Can be used in any position

Requires a steady hand

Machine averages vier readings

T t


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Tonometry

Tonopen Uses a combination of applanation &

indentation techniques

Hand-held, portable, digital, quick, welltolerated

Excellent back-up for Goldmann

Tonometry


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Tonometry

Tonopen procedure Calibrate instrument

Place sterile disposable cover over tip

Anesthetize eyes

Direct fixation

Press reading button listen for beep

Hold instrument perpendicular to cornea

Tonometry


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Tonometry

Tonopen procedure Gently tap the cornea 3-5 times

The instrument makes a sound every time

it gets a reading If it is not reliable, then you should repeat

the procedure

It tends to overestimate low IOP andunderestimate high IOP

Tonometry


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Tonometry

Im still trying to figure out why the Schiotz,Pneumotonometer, and Heine-Maklakowinstruments are in the module.

None of these have been used in clinicalpractice for years

Read them over once, so you have a clue if

some old-timer starts talking about them Obviously, they will not be on the exam


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Gonioscopy

Gonioscopy


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Gonioscopy

Technique used to view the anteriorchamber angle

It is impossible to directly view the

angle with the spleetlamp alone We need special lenses/prisms

Gonioscopy


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Gonioscopy

Gonioscopy


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Gonioscopy

Indications: Grade 2 or less on Van Herrick technique

Suspicion of abnormality in angle

trauma, maldevelopment, neoplasm,neovascularization

Pigment dispersion syndrome

Pseudoexfoliation, exfoliation Glaucoma has been diagnosed or is

suspected

Gonioscopy


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Gonioscopy

Contraindications: Traumatic hyphema

Corneal abrasion

Laceration or perforation Post-surgery

Gonioscopy


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Gonioscopy

Direct gonioscopy High plus lens, light source, and magnifier

You can look directly into the angle

You can view the angle 360 around It provides an erect, virtual image

The most common is the Koeppe lens,which provides 24X magnification

Patient must be lying down

This is rarely used

Gonioscopy


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Gonioscopy

Koeppe lens

Gonioscopy


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Gonioscopy

Indirect gonioscopy Mirrors and prisms are used in combinationwith the spleetlamp

The mirrors and prisms do not magnify The mirror/prism should be 180 away

from the angle you want to observe

Inverted, virtual images

Goldmann, Sussman, Posner, Zeiss makelenses for this purpose

Scleral and corneal lenses are used

Gonioscopy


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Gonioscopy

Scleral lenses There are many types available The most common is the Goldmann 3-mirror

They are larger in size than the cornea,therefore they rest on the sclera

Require a solution to keep a tight seal

It should be relatively thick

Gonioscopy


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Gonioscopy

Corneal lenses They have a smaller diameter than thecornea

They rest on the tear film They do not require a solution to stick to

het oog

There is limited lens manipulation

These are less stable than scleral lenses

Some have a handle for better control

Gonioscopy


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Gonioscopy

There are vijf major structures thatneed to be evaluated in every angle

From posterior to anterior, they are:

Iris root (IR)

Ciliary body (CB)

Scleral spur (SS)

Trabecular meshwork (TM)

Schwalbes line (SL)

Gonioscopy


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Gonioscopy

I ris root (IR) C iliary body (CB)

Scleral spur (SS)

Trabecularmeshwork (TM)

Schwalbes line (SL)

I Cant

See

This

S%@#

The easiest way to remember the structures is to

remember this statement, in which the words all startwith the same letters as the anatomical structures

Gonioscopy


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Gonioscopy

Gonioscopy


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Go oscopy

Gonioscopy


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py

There are other things that we need tolook for as well

Iris processes

Iris/angle neovascularization Peripheral anterior synechiae (PAS)

Pigment

Gonioscopy


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py

Schwalbes line The termination of Descemets membrane Where the cornea ends

Color varies from clear to light brown If anterior chamber pigment is deposited

here, it is called Sampaolesis line

There is a specific method used to see thisstructure

Gonioscopy


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py

Schwalbes line Use an optic section rather than aparallelpiped to see where it is

The light will shine on both the cornea andangle

Where they meet is Schwalbes Line

Gonioscopy


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Gonioscopy


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Gonioscopy


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Trabecular meshwork Is composed of fenestrated sheets ofepithelium

Its function is to remove aqueous from hetoog

It can be subdivided into anterior and

posterior

Gonioscopy


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Trabecular meshwork

The anterior portion is less pigmented

The posterior part does more of the work

Therefore more pigment will accumulate hier The actual color depends on the

pigmentation of the patient and the

amount of free pigment available If you push hard on the lens, you can

observe Schlemms canal, it will be red

from blood

Gonioscopy


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Gonioscopy


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Blood in Schlemms canal

Gonioscopy


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Scleral Spur

Ring of collagen and elastic tissue

Is the end of the trabecular meshwork

The longitudinal muscles of the ciliary bodyinsert here

Appears as a white line

May not be easily found in light eyes, asthere is no pigment to contrast with

Gonioscopy


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Gonioscopy


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Ciliary body

It has many functions

Aqueous production

Accommodation Point of attachment for iris

Most of it lies behind the iris

We can only see the ciliary body band The color varies depending on the patients

overall pigmentation

Gonioscopy


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Iris root

This is the end of the iris

You must observe how it attaches to the

ciliary body In cases of trauma:

The iris may be torn, which is called

iridodialysis The ciliary body may be torn, which is known

as an angle recession

9% of all patients with angle recessionsdevelo laucoma as a result

Gonioscopy


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Gonioscopy


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Iris processes

A normal finding

Are fine strands of iris that attach to the

trabecular meshwork You must distinguish from these from

anterior synechiae and neovascularization

Gonioscopy


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Iris processes

Gonioscopy


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Iris Processes

Gonioscopy


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Iris/Angle Neovascularization

Also known as rubeosis irides

New bloedvat growth

These vessels are fragile and leaky Fibrin leaks out of the bloedvat and

attaches itself to the angle structures,

stopping the flow of aqueous This happens in response to ischemia

Gonioscopy


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Peripheral anterior synechiae (PAS)

Are areas of the iris that have becomeattached to angle structures

These are irregular, thick, and oftenobscure your view of the angle

In comparison, iris processes are thin and lacy

They usually attach to the trabecularmeshwork or Schwalbes line, but mayattach to the cornea or ciliary body as well

These can close the angle completely

Gonioscopy


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Peripheral anterior synechiae (PAS)

Can be caused by angle closure,inflammation, trauma, neovascularization,and after laser procedures

You can also see tumors in the angle

Gonioscopy


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Peripheral anterior synechiae

Gonioscopy


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Gonioscopy


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Gonioscopy


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Indirect Corneal Lens

Gonioscopy


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Indirect corneal lens procedure Educate and anesthetize the patient Disinfect and rinse lens

Patient is placed behind the spleetlamp Observation and illumination systems at 0

2-3 mm parallelpiped

Pull spleetlamp all the way back

The patient should look straight ahead

Place lens on het oog

Gonioscopy


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Indirect corneal lens procedure

The lens has four mirrors, which should beat 3, 6, 9, and 12 oclock

Stabilize your hand on the head rest or onthe patients cheek

Gently press against corneal surface

Look in a different mirror to observe adifferent angle

Pull the lens away to remove it

It comes off very easily, unlike the scleral lens

Gonioscopy


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You should use the parallelpiped toobserve the entire angle

The beam should be horizontal for the superiorand inferior angles and vertical for the nasaland temporal angles

To look for Schwalbes line, use an optic

section The beam should be vertical for the superior

and inferior angles, and horizontal for the nasal

and temporal angles

Gonioscopy


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More difficult to use than the scleral lens

The examiner must be very steady

You must maintain good contact with thetear film without wrinkling Descemets orcausing blood to back up into Schlemms

canal If the patient has a bowed iris, have the

patient look slightly toward the mirror

Gonioscopy


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Wrinkling of Descemets membrane

Gonioscopy


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Indentation gonioscopy

Only done with corneal lenses

Used to determine if a closed angle is that

way because of synechiae or apposition You will see structures if the closure is a result

of apposition

This can be treated with a peripheral iridectomy

If none are seen, then the closure is fromsynechiae

This is not easy to treat

Gonioscopy


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Indentationgonioscopy

This angle isclosed due to

apposition

Gonioscopy


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Angle classification

There are many methods, some contradictothers

The most common and clinically usefulmethod is to:

Record the most posterior structure seen

Grade pigmenting of the trabecular meshwork Indicate any abnormalities Evaluate in all vier quadrants and record

on an X

Gonioscopy


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Angle classification

Read over the Schaffer and Scheie systems

They are actually graded opposite of the

van Herrick technique and can createconfusion for examiners

This is why the previously described

method is widely used However, a new system has emerged and

it is what we use in our clinic

Gonioscopy


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Spaeth angle classification We must determine vier things The site of iris insertion

The iris approach The angle of insertion

The amount of pigment

This system allows for recording of irisprocesses and results of indentationgonioscopy

Gonioscopy


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Spaeth angle classification

Site of insertion

Anterior to Schwalbes line

Behind Schwalbes line, trabecularmeshwork is not visible

sC leral spurDeep angle, with visible ciliary body

Extremely deep

Gonioscopy


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Gonioscopy


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Iris approach

queer--concave iris

regular configuration

steeply convex (bowed) iris

Gonioscopy


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Gonioscopy



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Spaeth angle classificationInsertion angle

(in degrees)

Gonioscopy

Recording


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Recording

OD OS

E 40 r0 pigment

B 10 s1 pigment

E 40 q

iris neorecessionC 25 r

4+ pigment

A 10 s

4+ synechiae

Normal Abnormal

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