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

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).

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

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  1. Sheila McGilvraySenior Charge Nurse Ophthalmology Ward 25Ninewells HospitalNHS Tayside 23rd Aug 2007 Retinopathy Screeners Training Course

  2. Testing Visual Acuity & Dilating the eyes for photography

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

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

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

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

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

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

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

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

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

  12. Recording VA • 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

  13. 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) • If unable to CF then examiners hand is moved in front of patients eye (HM) • Failure to see examiners hand move • Check with pen torch perception of light (POL) • If no light seen by patient (NPL)

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

  15. Pin-hole • 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

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

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

  18. Tropicamide 1% preferred mydriatic • Tropicamide is an anticholinergic. Causes - mydriasis & cycloplegia • Rapid action 15-20 mins. • Duration - 4 - 6 hours • Parasympatholytic drug • 1% paralyses accommodation

  19. 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 • If brow or eye pain occurs, red eye, nausea, vomiting contact nearest eye department

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

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

  22. Conclusion • Recording VA important part of ophthalmic examination • 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

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