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Essential contact lens practiceIn the second part of our series covering aspects of contact lens practice,Jane Veys, John MeylerandIan Daviesreview practical considerations for slit-lamp examination of the contact lenswearer. C6392, two contact lens points, suitable for optometrists, DOs and CLOs

22 |Optician | 06.04.07

The slit lamp, or biomicro-scope, is probably the singlemost important objectiveinstrument in contact lens

practice, allowing detailedexamination of the anterior segmentof the eye. Slit-lamp examination is anessential aspect of pre-assessment of thepotential contact lens wearer (neophyte)and in the aftercare of the existingwearer.

Guidelines from professional bodies,such as the College of Optometrists(UK), specify the contact lens practi-tioner must have a slit-lamp microscope.1The guidelines further specify that thepractitioner must carry out a physicalassessment of those tissues which can

be affected by contact lens wear forexample, the cornea, the conjunctiva,limbus, lids and tears. The slit-lampprovides the optimum means to carryout this assessment.

Slit-lamp examination of the neophytehas two purposes to assess the suitabil-ity of the eye for contact lenses and toprovide baseline data from which anychanges during the course of contact lenswear can be measured. Furthermore, inthe fitting process, the slit lamp has a rolein assessing the physical fit of lenses insitu, rigid as well as soft. In contact lens

aftercare, the slit lamp allows the practi-tioner to make an objective judgement ofthe interaction between the lens and theeye, as well as a crude assessment of lensspoilation. This instrument, then, has arole to play in all aspects of contact lenspractice, and indeed routine practice ingeneral.

InstrumentationAll major instrument manufacturersproduce a range of slit lamps. While thebasic principle of the biomicroscope isthe same whichever model is chosen,

there are several aspects to be consideredin choosing a new instrument.Slit lamps can be categorised into

two broad groups those with theillumination system above the viewingsystem (Figure 1) and those with the

Part 2 Slit-lamp examination

illumination below the viewing system(Figure 2). The key points to be consid-ered in choosing a slit lamp are:

IlluminationA bright illumination system is one ofthe two fundamental requirements fora slit lamp. While halogen lamps aremore expensive than tungsten systems,they provide a brighter, clearer lightand should be the system of preference.There should also be a means of control-ling the intensity of the light.

While neutral density filters allow theinvestigator to reduce illuminance, theyare not as flexible or as fast as a rheostat.

A rheostat has the added advantage ofallowing instant control for the exami-

nation of the photophobic patient.

Viewing systemThe second prerequisite for a slit lampis the viewing system that provides aclear image of the eye and has sufficientmagnification for the practitioner toview all structures of the eye.

Binocular viewing permits improvedjudgement of depth. The slit lampshould be capable of a magnificationup to at least 40X. This can be achievedthrough interchangeable eye pieces and/or variable magnification of the slit-lamp

objective.Ideally, the practitioner should be ableto change magnification easily and thisgives slit lamps with four or five differ-ent objectives an advantage.

Zoom systems have the added advan-

tage of allowing the practitioner to focuson a particular structure without losingsight of it. The importance of choosinga slit lamp with a high-quality opticalsystem cannot be over-stated.

Slit adjustmentsThe slit in the illumination system must

be capable of adjustment. In most slitlamps adjustment is variable, which isdesirable.

The practitioner should be able toadjust slit width and height easilywithout having to fumble for controls.

KEY POINTS

A slit-lamp with a good range of magnification

and excellent optics is essential for contact lens

practice Establishing a routine aids a thorough and

comprehensive examination of all ocular tissue

Use of a fluorescin is essential to examine ocular

integrity. An additional barrier filter will enhance

observation

Adapting a grading system is essential for

accurate and comprehensive records

Figure 1Slit-lamp with illumination system

above viewing system, with image capture

options

Figure 2Slit lamp with illumination system

below the viewing system

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It should also be possible to orient the slithorizontally, as well as vertically. Morepreferable still is orientation at all angles(Figure 3), especially useful with softtoric fitting and rigid alternating bifocal

fitting.In slit lamps without a graticule, the

slit width should be measurable to assistin reviewing the size of any lesionsobserved.

Viewing accessoriesThe slit lamp must have a cobalt-bluefilter for fluorescein excitation. It shouldalso have, or have a means of adding, abarrier filter to facilitate fluorescein

viewing. Many slit lamps also have ared-free filter to aid the observation ofvascularisation.

Mounting and adjustments

The feel of a slit lamp is personal, itshould be easy to use and operate. Asingle joy-stick assists in this process andleaves a hand free for manipulating theeye during the examination. The slitlamp should have a locking device tohold it in position if required.

The choice of table and stand shouldalso be considered in the selection of aparticular instrument. Practitioners willbenefit from the slit lamp being mounted

on a combi unit which can easily bemoved in front of the patient to carry outthe examination. Tables are also availablewhich have a common head and chinrest for both keratometer and slit lamp.

These save the practitioner timeby maintaining the patients positionbetween examinations with eachinstrument.

Additional featuresSlit lamps have the facility to add onspecialist attachments. These includean applanation tonometer for measure-ments of intraocular pressure, a 60D,78D or 90D lens for fundus examination

Figure 3aSlit beam orientation: vertical Figure 3bSlit beam orientation: horizontal Figure 3cSlit beam orientation: oblique

TABLE 1

Summary of structures and conditions viewed at each stage of the slit-lamp examination

Illumination Magnification Filters Slitwidth

Structures examined Conditions evaluated

Direct Low No Wide Lashes Blepharitis

Bulbar conjunctiva

Palpebral conjunctiva

HyperaemiaPterygiumPingueculumFolliclesPapillaeHyperaemia

Medium/high No Wide Lid margins

Contact lens

Meibomian glandsPatency of tear ductsFit

No

Red-free

Medium Cornea

IrisContact lens

Limbus

Opacities

NaevusSurface qualityEngravingsWettingVascularisation

High No Narrow Cornea

Tear film

DellenStriaeFoldsDepth of lesionsEndothelial morphologyDebris

Medium/high Blue Medium CorneaConjunctiva

StainingStaining

Indirect Low No Medium Cornea Corneal opacities

Central corneal cloudingHigh No Narrow Corneal epithelium

Limbus

MicrocystsVacuolesVasculartisation

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(Figure 1), a gonioscope for examinationof the anterior chamber, a pachymeterfor measurement of corneal thicknessand an anaesthesiometer for cornealsensitivity.

The increased accessibility of digitalphotography means that, when select-ing a new slit lamp, the option to havea digital camera attached should beconsidered.

Photography and image captureSlit-lamp observations can be limitedby the practitioners individual memory,consistency of grading and artistic skillduring record keeping.

Photography of the eye provides analternative and accurate means of record-ing tissue appearance. Traditionally, the

most frequently used option for imagecapture of the anterior segment involvedthe use of a photographic slit lamp with abeam splitter attached to a 35mm cameraback.2,3

Conventional 35mm photographyrequires a certain level of expertise toensure the correct exposure and unfor-tunately the results cannot be viewedin real time. Recent advances in videocameras, image-capture boards, digitalstill cameras and colour printers hasresulted in an affordable alternative to35mm photography, namely digital

image capture.To create a digital image, four basic

components are required:A system for recording the image(for example, video camera or digitalstill camera)A system for converting the imagedata to a digital file (for example, imagecapture board) A system for image storage andretrieval (eg CD-Rom, hard disk) A system for viewing the image(SVGA monitor, quality colour printer).

The major advantage of such systemsis the ability to generate instantane-ous images on the computer monitorfollowing capture. Poor quality imagescan be deleted with ease and furtherimages recorded until satisfied. Imagequality can often be improved by usinga separate background illuminationsource (Figure 4). The instant nature ofdigital imaging has the additional advan-tage of supporting patient education;for example, demonstrating the benefitsof disposable/frequent replacementcontact lenses as well as the importance

of regular aftercare.While digital photography can bea valuable adjunct to normal recordkeeping, it is important that it should notreplace the physical record. The qualityof the image obtained is dependent on

many variables, the key one of which isthe exposure.

Over-exposed images will washout the eye and light any conjunctivalredness, while under-exposed images

will accentuate some changes to the eye.The practitioner with a digital cameraneeds to calibrate the instrument anddesign a protocol which is dependent onthe instrument, as well as any ambientillumination for each type of illumi-nation and magnification that will beused. The image captured with a digitalcamera is also a one-dimensional imageversus the three-dimensional image seenthrough the viewing system. The practi-tioner also needs to be aware of which ofthe two viewing tubes is being used tosplit the image to the camera, particularly

important when looking at high magni-fication images.

One further consideration in thephotography of the eye is that the imageplane for the camera may be differentfrom the rest of the viewing system.The practitioner must ensure the imagebeing photographed is in focus. This canbe achieved by checking the monitorrather than just relying on the imageseen through the eye pieces, again this isvery much dependent on the image andthe calibration.

Finally, a digital image is still a record

which must be maintained as otherrecords and backed up appropriately. Asthe image is held digitally, the practi-tioner needs to take into considerationdata privacy laws. Further informationon this form of image capture can beobtained from the literature.4,5

Technique

Setting upA correct set-up of the biomicroscopeis essential. The illumination and obser-vation systems must be coupled and in

focus for the observer, and the patientmust be seated comfortably, with his orher chin in the rest, head firmly againstthe headrest and eye level at the centre ofthe vertical travel of the instrument. Thestages needed to achieve this are:Instrument focusing Using the focus-ing rod provided with the slit lampensures a narrow slit beam is clearly infocus through each eyepiece individually,and then binocularly, through adjust-ment of the interpupillary distance of theinstrument. Assuming only one personis using the instrument, this procedure

only needs repeating periodicallyPatient position Explain to the patientthe nature of the examination and ensurethey are seated comfortably. This is criti-cal. If they are uncomfortable, the exami-nation becomes significantly more

24 |Optician | 06.04.07

Figure 4aPhotograph taken without

background illumination

Figure 4bPhotograph taken with backgroundillumination

Figure 5 Contact lens deposits observed

under dark-field illumination

TABLE 2

Structures and lesions requiring measurementor grading

Objective measurement Subjective grading

Microcysts (number)Vascularisation (size & position)

Folds (no)Striae (no)Pingueculum/pterygium (size)Opacities (size and position)

StainingFollicles

PapillaeHyperaemiaDepositionTear film

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difficult. Similarly, if the eye level is notin the middle of the instruments verticaltravel, the examiner will have difficultylooking at the inferior and superior partsof the eye. Most slit-lamps have a notchon the headrest which should be lined

up with the outer canthus of the eye toensure the head position is optimal Focusing check With the eyelidsclosed the examiner should focus thelight on the lids and check its focus byrotating the illumination system fromside to side. As it rotates, the light shouldremain stationary on the lid. If it isshowing relative movement, the instru-ment is not in focus Patient examination The examina-tion can now begin. The slit beam shouldnever be left shining on the eye when thepractitioner is carrying out an examina-

tion. If the practitioner is looking awayfrom the eyepieces, the beam should beturned off or directed away from theeye.

Slit-lamp routineAs with many aspects of contact lensand ocular examination, the practi-tioner should develop a routine whichenables them to cover all aspects of theassessments in a logical and consistentmanner. Slit-lamp examination of theeye comprises several different illumi-nation techniques. These techniques are

described in detail by various authors.6,7,8,9 This article describes the clini-cal routine in general terms. Table 1summarises the illuminations used andthe structures and conditions viewed ineach sweep of the eye.

The order of the examination willvary from one practitioner to the next.Typically, the examination will start

with low magnification and diffuseillumination for general observation,with the magnification increasing andmore specific illumination techniquesemployed to view structures in greaterdetail. In slit-lamp examination of the

contact lens wearer, high magnificationand direct illumination must be used tocheck for striae, folds and microcystsimmediately after lens removal, as thesemay disappear with time.

Beyond this specific request, the practi-tioner should carry out the examinationusing the least invasive techniques first.In particular, fluorescein instillation andlid eversion should occur towards theend of the examination, after tear qualityhas been assessed, to avoid disruption tothe tear film.

Overall view Low magnification,wide diffuse beamThe practitioner should carry out severalsweeps across the anterior segment andadnexa with a broad beam and lowmagnification. Starting with the lidsclosed, the lid margins and lashes shouldbe examined for signs of marginalblepharitis or styes. Next, the patientshould be asked to open his or her eyes,and the lid margin be examined forpatency of the tear ducts and meibomianglands.

Once upper and lower margins have

been examined, the practitioner shouldlook at the bulbar conjunctiva to assesshyperaemia and the possible presence ofa pingueculum or pterygium. This illumi-nation should also be used to view thesuperior and inferior palpebral conjunc-tiva for hyperaemia, follicles and papillae.

This illumination would also be usedto give an assessment of soft lens fit

in terms of centration, movement andtightness. Diffuse illumination mayalso be used to assess lens spoilationby dark-field illumination. For this, thelens should be removed from the eye,held in the slit beam in the plane of the

headrest, and viewed under magnifica-tion through the eyepieces (Figure 5).Lens spoilation cannot be effectivelyviewed with the lens on the eye.

Corneal and limbus examinations Medium magnification, 2mm beamThe practitioner typically starts thecorneal examination by placing the slitat the limbus and, with room lights off,observing the cornea for gross opacifica-tion or central corneal clouding producedby hard lens wear.

The viewing system needs to be uncou-

pled from the illumination system if thecornea is to be viewed under magnifi-cation by this means, although viewingwith the naked eye may be sufficient.Once the cornea has been examined bysclerotic scatter, the illumination andviewing system must be recoupled anda series of sweeps carried out across thecornea.

The practitioner should start bymoving around the limbus, looking atthe limbal vasculature to assess the degreeof physiological corneal vascularisation(blood vessels overlaying clear cornea)

and differentiate between that andneo-vascularisation (new blood vesselsgrowing into clear cornea Figure 6).

Blood vessels are seen in both directillumination, looking directly over thearea of cornea illuminated, or indirectretroillumination, looking to the side ofthe illuminated cornea. A red-free (green)filter aids in the detection of vasculari-

Figure 6 Physiological loops combined with some

neovascularisation Figure 7 Optical section of cornea Figure 8 Microcysts with neovascularisation

TABLE 3

The CCLRU grading for cornea staining11

Type Depth Extent of surface involvement

0 Absent1 Micropunctate2 Macropunctate3 Coalescent macropunctate4 Patch

0 Absent1 Superficial epithelial involvement2 Stromal glow present within 30 secs3 Immediate localised stromal glow4 Immediate diffuse stromal glow

0 Absent1 1% to 15%2 16% to 30%3 31% to 45%4 46% or greater

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sation. As well as examining for blood

vessels, the practitioner is also lookingfor peripheral infiltrates or dellen duringthis part of the examination.

Once the limbus has been assessed, thepractitioner sweeps across the cornea,looking for any gross abnormalitiesbefore narrowing the beam and increas-ing the magnification to examine thecornea in detail.

Corneal examination Highmagnification, narrow beamIt is at this stage of the examination thatthe slit width is reduced to its minimum,

allowing the practitioner to view thecornea in cross-section (Figure 7).

With high magnification, the corneais swept systematically. A routine isessential to ensure that none of thecornea is missed. As well as looking foropacification and recording depth andlocation, the practitioner is also lookingfor microcysts, seen in retroilluminationto the side of the direct beam (Figure 8),stromal striae and folds in the endothe-lium. During the aftercare of a soft lenswearer, this process will be the first partof the slit-lamp examination to be carried

Figure 9Appearance of endothelium observed

at medium/high magnification

(Courtesy of Haag-Streit)

Figure 11Absorption and emission

characteristics of fluorescein and slit-lamp

photographs taken with (right) and without

(left) barrier filters

out, as signs of oedema disappear shortlyafter lens removal.

The final aspect of the corneal examina-tion under white light and high magnifi-cation is observation of the endothelium.

Many practitioners report this to be oneof the most difficult corneal structuresto examine. Even at 40X magnification,only a gross clinical judgement can bemade as it is not possible to view individ-ual cells. Furthermore, only a small areaof endothelium will be seen at any onetime.

The technique for viewing theendothelium involves using a slightlybroadened slit beam and setting up theillumination system and microscope sothe angle of incident light is equal to theangle of reflection.

The area of specular reflection is onlyvisible monocularly. Focusing on theback of the corneal section, the endothe-lium comes into view as a patch with adull gold appearance (Figure 9).10

More detailed assessment of cell count,size, shape and density can be carried outusing a specular microscope which arebecoming increasingly accessible for thepractitioner in routine practice. Modernspecular microscopes give the practi-tioner the opportunity to both viewthe endothelium and calculate endothe-lial cell density, polymegathism and

pleomorphism. In the absence of suchequipment, a clinical grade is best madeby comparison with a photographicgrading scale, such as that published bythe Cornea and Contact Lens ResearchUnit (CCLRU).11

Staining

FluoresceinThe cornea must be examined follow-ing fluorescein instillation, both prior tocontact lens fitting and at every after-care appointment. Sodium fluorescein

TABLE 5

Lens deposit classification12

Class Heaviness of deposit

IIIIIIIV

CleanVisible under oblique light when wet using 7X magnificationVisible when dry without special light, unaided eyeVisible when wet or dry with the unaided eye

Class Type of deposit

CGFP

CrystallineGranularFilmyPlaque

Class Extent of depositabcd

0-25% of lens25-50% of lens50-75% of lens75-100% of lens

Figure 10Fluorescein helps to highlight papillae

TABLE 4

US FDA clinical grading

01

2

3

4

NormalSlight or mild changes fromnormal that are clinicallyinsignificantModerate changes thatmay require clinicalinterventionSevere changes thatusually require clinicalinterventionVery severe changes thatrequire intervention, oftenmedical

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is a vital stain which colours damagedepithelial tissue. It is the best means of

judging corneal and conjunctival integ-rity, and in particular can highlight tissuechanges such as CLPC (Figure 10).

Practitioners should not shy away fromusing fluorescein in soft lens wearers asit will reveal changes in corneal integritywhich could not otherwise be seen.

Although fluorescein also has thepotential to stain hydrogel material, onlythe minimum amount is needed in thetear film to visualise any disruption tocorneal integrity. If a fluorescein-impreg-nated strip is first wet with sterile saline,shaken clear of excess fluid and dabbedin the lower lid, enough will be intro-duced into the fornix. This will dissipatequickly to allow insertion of soft lenses

within 10 minutes without risk of thembeing stained.

Fluorescent substances absorb lightat specific wavelengths and emit theabsorbed energy at longer wavelengths.Fluorescein absorbs blue light in theregion of 460nm to 490nm and emits ata high wavelength (maximum 520nm).However, the illuminating cobalt-bluelight and the emitted green light fromthe fluorescein must be of roughly equalintensity.

The appearance of fluorescein in theeye may be enhanced by placing a yellow

barrier filter over the eyepiece. Thisfilters the blue light to make the fluores-cent green stand out more clearly (Figure11). An assessment of corneal stainingwith fluorescein is essential and must becarried out at each appointment.

Lissamine greenLissamine green is increasingly takingover from rose bengal as a the preferredstain for examination of the conjunctivain dry-eye patients.

It stains damaged conjuctival stainsand is significantly more comfortable

to the patient on installation. Stainingfades quickly and so requires assessmentimmediately after installation. Whilemany propose its examination underwhite light where the area of stainingwill apprear green, others recommendthe use of a red filter (Wratten No25)to enhance the viewing.11 Lissaminegreen staining has higher specificitywith symptomatic patients with dry-eyesymptoms than fluorescien.12

Recording resultsOf equal importance to carrying out

the examination is recording the results.In law, if an action is not recorded it isdeemed not to have taken place. It isnot sufficient to say cornea clear thepractitioner must attempt to record andquantify what is seen.

1In which of the following does thebio-microscope not play a role?

AAssessing corneal shape factorBAssessing hard lens fitting characteristics

CEvaluating neovascularisation

DJudging extent of lens deposits

2Which of the following statements aboutthe slit lamp is true?AThe red free enhances the contrast of corneal

staining

BThe illumination and observation systems are

coupled to maximise light intensity on the

cornea

CA photo-slit lamp is essential if the

practitioner wants to photograph the eye

DThe illumination and observation systems arecoupled to allow a three-dimensional view of

the eye

3Which of the following is best visualisedusing high magnification directillumination with a narrow slit beam?

ANeovascularisation

BStriae

CMicrocysts

DCorneal staining

4Which of the following is best viewedusing high magnification, indirectillumination and a narrow slit beam?

AEndothelial folds

BMicrocysts

CPolymegathism

DDepth of corneal lesions

5Which of the following should berecorded as a subjective grade?AMicrocysts

BPalpebral hyperaemia

CEndothelial folds

DSize of corneal opacities

6Why is a yellow barrier filter

recommended?ATo be placed over the illumination system to

enhance contrast when using fluorescein

BTo be placed over the observation system to

enhance contrast when using fluorescein

CTo shift the wavelength of the incident light

on the cornea

DTo help in assessment of neovascularisation

7Using the CCLRU grading scale, howwould the SEAL in Figure 12 (below) begraded?

Type Depth Extent

A 2 3 2

B 2 3 1

C 3 3 1

D 4 3 1

8Using the FDA grading scale, how wouldthe SEAL in Figure 12 be graded?A0

B1

C2

D3

9When should fluorescein be used?

AAt the preliminary examination and rigid lens

after care

BAt the initial examination and all lens after

care

CAt the initial examination and when a problem

is suspected with soft lenses

DOnly with rigid lens wearers

10How can contact lens deposits bestbe controlled with the slit-lamp?A In vivo, direct illumination high magnification

BIn vivo, indirect illumination high

magnificationCBy sclerotic scatter

DIn vitrousing diffuse illumination

EIn vitrousing an optic section

11Which of the following statementsconcerning lid eversion is false?ACarry out with fluorescein instilled

BPermits detection of CLPC

CCarry out prior to tear-film assessment

DForms part of routine aftercare for all contact

lens wearers

12At what wavelength will excited

fluorescein emit light?A460nm

B490nm

C500nm

D520nm

MULTIPLE-CHOICE QUESTIONS

To take part in this module go to opticianonline.net and click on the Continuing Education

section. Successful participation in each module of this series counts as two credits towards

the GOC CET scheme administered by Vantage and one towards the Association of

Optometrists Irelands scheme. The deadline for responses is May 3, 2007

Figure 12

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With the graticule in situsome condi-tions can be measured, while others haveto be graded using an established system.Table 2 lists structures and lesions that canbe measured and those that need grading.

Grading schemes may be quantitative,for example corneal staining (Table 3),or banded according to clinical judge-ment as used by the US Food and Drug

Administration (Table 4). There areseveral different grading systems avail-able which have been validated for clini-cal use.

While there are advantages and disad-vantages of each it is important thatthe practitioner sticks to the use of onesystem. The confidence limits on gradingwith a 4-5 point published system are1.2 grading scale units.14

It is not only the appearance of ocularstructures that requires grading. Aspectsof the contact lens must also be recorded.For example, spoilation may be classifiedaccording to Rudko (Table 5).15

SummaryThe slit-lamp examination is arguablythe most important aspect of contact lenspractice, both for judging the potential ofa prospective lens wearer and monitoringthe established wearer. The examinationmust be comprehensive and objectively

recorded. The practitioner should ensurethe slit lamp utilised is capable of viewingthe subtle changes that may occur due tocontact lens wear.

References

1The British College of Optometrists

(1991). Contact lens practice code of ethics

and guidelines for professional conduct.

Chapter 5 (Revised 1993).

2Lowe R. Clinical slit lamp photography

an update.Clin Exp Optom,1991; 74 (4):

125-129.

3Bowen K P. Slit-lamp photography.Contact

Lens Spectrum, 1993; 8: 7 27-32.

4Meyler J and Burnett Hodd. The use of

Digital Image Capture in Contact Lens

Practice.Contact Lens and Anterior Eye

(supplement), 1998; 21:3-11

5Morgan P, Morris T, Newell Z, Wood I andWoods C (). Invasion of the Image Snatchers.

Optician,1997; 213 (5588), 24-26.

6Jones L, Veys J and Bertrand P. Slit-lamp

Biomicroscopy how to expand your

routine. Optician,1996 Part one 5542 211:

19-22; part two 5545 211: 16-19; part

three 5550 211: 30-32.

7Chauhan K. The Slit-lamp and its use.

Optician1999 5692 217: 24-30

8Brandreth R H. Clinical slit-lamp

biomicroscopy. 1978, Blaco, San Leandro.

9McAllister, C Slit lamp biomicroscopy Part

1. Optician,2006; 232:6065:20-27

10Morris J and Morgan P. The cornea. Part II

xamination, assessment and measurement.

Optician, 1994; 207: 51446 16-21.

11Terry R et al. The CCLRU standards for

success of daily and extended wear contact

lenses. Optom and Vis Sci,1993; 70: 3

234-243.

12Matheson A. The use of stains in dry eye

assessment.Optician,2007; 233:6091:26-

31

13Guillon M, Maissa C. Bulbar conjunctival

staining in contact lens wearers and non

lens wearers and its association with

symptomatology. Contact lens and Anterior

Eye,2005; 28:67-73

14Efron, N. Morgan PB, Katsara SS.

Validation of grading scales for contact lens

complications.Ophthal Physiol Opt, 2000;

21:1:17-2915Rudko P. A method for classifying

and describing protein deposition on the

hydrophilic lens. Allergan Report SeriesNo

94 (1974).

Jane Veysis education director, The

Vision Care Institute, Johnson & Johnson

Vision Care.John Meyleris senior director,

professional affairs, Europe, Middle East &

Africa, Johnson & Johnson Vision Care. Ian

Daviesis vice president, The Vision Care

Institute, Johnson & Johnson Vision Care

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