Sheila McGilvray Senior Charge Nurse Ophthalmology Ward 25 Ninewells Hospital NHS Tayside 23 rd Aug 2007 Retinopathy Screeners Training Course

Testing Visual Acuity & Dilating the eyes for photography

Testing Visual Acuity (VA) Initial part of any ophthalmic examination/photography/treatment Initial part of any ophthalmic examination/photography/treatment A National grading protocol A National grading protocol Visual performance is dependent on Visual performance is dependent on –Integrity of retina, visual pathway –Quality of retinal image –Ambient light level

Methods of Testing VA Most common - Snellen Test Chart Most common - Snellen Test Chart Gold Standard – EDTRS chart LogMAR Gold Standard – EDTRS chart LogMAR Kay Picture Test or Sheridan Gardiner Kay Picture Test or Sheridan Gardiner E Chart E Chart

Snellen Test Type Standard method – in Tayside the software converts Snellen to LogMAR Standard method – in Tayside the software converts Snellen to LogMAR Not very sensitive for poorer visual acuities Not very sensitive for poorer visual acuities The progress of letter sizes is unequal The progress of letter sizes is unequal Get a crowding effect Get a crowding effect Not mathematically sound Not mathematically sound

Snellen Test Type Rows designated by ratio - test distance to distance normal person reading that sized letter Rows designated by ratio - test distance to distance normal person reading that sized letter Mobile screening vans allow for 3m test type Mobile screening vans allow for 3m test type For example – if a patient reads only 3/60 For example – if a patient reads only 3/60 the 3/= distance from chart the 3/= distance from chart the /60 = seen by person with standard acuity at 60 m the /60 = seen by person with standard acuity at 60 m

EDTRS chart LogMAR Recommended Gold Standard Recommended Gold Standard Better chart design Better chart design High contrast lettering High contrast lettering Letters set at equal linear steps, equal spacing Letters set at equal linear steps, equal spacing Contains a near equal score of difficulty on each line Contains a near equal score of difficulty on each line More effective analysis and comparison of results More effective analysis and comparison of results

LogMAR Patient seated at 2m Patient seated at 2m Separate chart for each eye Separate chart for each eye More consistent level of illumination More consistent level of illumination

Preparation for Snellen Test Type Patient comfort and privacy improves compliance Patient comfort and privacy improves compliance Sit back in chair not leaning forward Sit back in chair not leaning forward Chart illuminated appropriately at 3m Chart illuminated appropriately at 3m Occluder with pinhole Occluder with pinhole Hand washing facilities Hand washing facilities

Preparation and procedure Explain procedure to patient Explain procedure to patient Check if patient uses contact lenses, distance glasses Check if patient uses contact lenses, distance glasses Check each eye separately, right first Check each eye separately, right first Use ocluder to ensure other eye covered Use ocluder to ensure other eye covered Advise wiping ocluder between patients with an alcohol wipe Advise wiping ocluder between patients with an alcohol wipe

Recording VA Record if vision tested unaided or with corrective glasses or contact lenses Record if vision tested unaided or with corrective glasses or contact lenses - unaided (UA) - glasses worn (GL) - contact lenses (C.L.) - contact lenses (C.L.) Example result - RVA LVA Example result - RVA LVA 3/6 glasses 3/12-2 3/6 glasses 3/12-2 PH 3/9-1 PH 3/9-1

Recording VA If only half of line read If only half of line read e.g. 3/9 Record as either 3/9 minus no. of letters missed or 3/12 + number of letters seen on 3/9 line

If unable to see any letters and if practical move chart nearer to patient If unable to see any letters and if practical move chart nearer to patient Or examiner holds up hand at 1m, patient asked to count fingers (CF) Or examiner holds up hand at 1m, patient asked to count fingers (CF) If unable to CF then examiners hand is moved in front of patients eye (HM) If unable to CF then examiners hand is moved in front of patients eye (HM) Failure to see examiners hand move Failure to see examiners hand move Check with pen torch perception of light (POL) Check with pen torch perception of light (POL) If no light seen by patient (NPL) If no light seen by patient (NPL)

Using Pin-hole If reading less than 3/6 then use pin-hole If reading less than 3/6 then use pin-hole Allows only central light rays into eye along the visual axis Allows only central light rays into eye along the visual axis Eliminates blurring of vision if refractive error present Eliminates blurring of vision if refractive error present Using patient’s hand - risk of error, may not fully occlude their eye Using patient’s hand - risk of error, may not fully occlude their eye

Pin-hole If acuity improves it usually indicates refractive error e.g. cataract If acuity improves it usually indicates refractive error e.g. cataract If VA worse through pin-hole over best correction macular disease must be considered If VA worse through pin-hole over best correction macular disease must be considered

Preparation for pupil dilation National Procedure Try photos on undilated eye If photography fails then dilate Effects exposure image Effects exposure image Ability to capture multiple fields Ability to capture multiple fields

Checks prior to instillation of mydriatic drops Patient name DOB CHI Patient name DOB CHI Known allergies Known allergies Explain procedure and effect of drops- transient stinging, blurred vision Explain procedure and effect of drops- transient stinging, blurred vision Check correct drop & dose, record batch no. & expiry date on softwear Check correct drop & dose, record batch no. & expiry date on softwear Wash hands Wash hands

Tropicamide 1% preferred mydriatic Tropicamide is an anticholinergic. Causes - mydriasis & cycloplegia Tropicamide is an anticholinergic. Causes - mydriasis & cycloplegia Rapid action mins. Rapid action mins. Duration hours Duration hours Parasympatholytic drug Parasympatholytic drug 1% paralyses accommodation 1% paralyses accommodation

Patient Information Inform patient of effects of Tropicamide –Transient stinging –Blurred vision –Photophobia - sensitivity to light Warn not to drive or use machinery until vision is clear Warn not to drive or use machinery until vision is clear If brow or eye pain occurs, red eye, nausea, vomiting contact nearest eye department If brow or eye pain occurs, red eye, nausea, vomiting contact nearest eye department

Contraindications Eyes predisposed to acute glaucoma (shallow-angle and shallow anterior chamber) Eyes predisposed to acute glaucoma (shallow-angle and shallow anterior chamber) Hypersensitivity Hypersensitivity Systemic effects not expected due to short duration. Systemic effects not expected due to short duration. Reduced by compressing lacrimal sac at medial canthus Reduced by compressing lacrimal sac at medial canthus

Adverse event following mydriasis Patient knows how to access advice Patient knows how to access advice Tayside have a 24 hour point of contact at Ophthalmology ward 25, Ninewells Tayside have a 24 hour point of contact at Ophthalmology ward 25, Ninewells Availability of on call Ophthalmologist if patient symptoms necessitate review Availability of on call Ophthalmologist if patient symptoms necessitate review

Conclusion Recording VA important part of ophthalmic examination Recording VA important part of ophthalmic examination Preparation, check patients details & history before procedure & instilling mydriatic drops Preparation, check patients details & history before procedure & instilling mydriatic drops Inform patient of effects of mydriatic drops, given Ophthalmology dept. phone no. if advice required Inform patient of effects of mydriatic drops, given Ophthalmology dept. phone no. if advice required