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Bitten by Ophthalmology

Bitten by Ophthalmology. Professor Helen Danesh-Meyer University of Auckland. 5 Keys steps for assessment of optic nerve function. VA Colour Vision Relative afferent pupillary defect Visual Field Optic Nerve. 1. Visual Acuity. Best Corrected. Pinhole. Papillo -macular bundle.

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Bitten by Ophthalmology

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  1. Bitten byOphthalmology Professor Helen Danesh-Meyer University of Auckland

  2. 5 Keys steps for assessment of optic nerve function • VA • Colour Vision • Relative afferent pupillary defect • Visual Field • Optic Nerve

  3. 1. Visual Acuity Best Corrected Pinhole

  4. Papillo-macular bundle

  5. Glaucoma • A collective term for group of potentially blinding ocular conditions • Characterised by peripheral visual field loss and characteristic changes to the optic nerve head • Can be: • primary (occur by themselves), or • secondary (other ocular condition causes it)

  6. Adult onset (> 40yrs) Angle normal and open Higher IOP greater risk Glaucomatous optic nerve head damage Visual Field loss Normal Glaucoma Primary Open Angle Glaucoma cup c/d = 0.3 disc cup c/d = 0.8 disc

  7. Open Angle Glaucoma • Asymptomatic • Genetic • Visual loss is irreversible • Most common cause of preventable blindness • Treatment is lifelong

  8. 2. Colour vision • Optic nerve disease has decreased colour out of proportion to VA. • Red desaturation classic for compressive optic neuropathies • Tests: • Ishihara • Red target

  9. 3. Relative Afferent Pupillary Defect

  10. 3. Relative Afferent Pupillary Defect • Objective sign of optic nerve compromise • Can be used to monitor progression • Provides a comparison of the two optic nerves

  11. Relative Afferent Pupillary Defect (RAPD) • Test in dim room with pt looking at the distance • Use bright source of light about 30cm from pt’s eyes • Swing light b/w the eyes (2-3 sec on each eye) • Make your decision within 2-3 swings

  12. Observe Photopic illumination Scotopic illumination

  13. Light responses Direct response Consensual response

  14. Light responses Consensual response Direct response

  15. Abnormal response Right Relative Afferent Pupillary Defect

  16. Circumstances when RAPD assessment difficult • Both pupils dilated • Dark irides • Elderly- small constricted pupils • Damage to iris by surgery (cataract) • Presybopic examiner

  17. Surrogate Tests for RAPD Brightness sense Red perception

  18. Brightness sense • Test in dim room with pt looking directly at the light • Use bright source of light • Ask: • Is light equally bright in both eyes? • If light is 100% bright in this eye (or worth 100 dollars) then how many percent (or how many dollars) is it in the other eye?

  19. 4. Visual Field Assessment

  20. Nasal Temporal Nasal Temporal Anatomy of visual pathway Right eye Left eye

  21. Anatomy of visual pathway Nasal retina Temporal retina Temporalretina Optic nerve Optic tract Optic chiasm Lateral geniculate body Optic radiation Modified from Kahle W.Frotscher M: Color Atlas and Textbook of Human Anatomy. 5th ed. Stuttgart: Thieme. Vol.3 p.355, 2003 Striate cortex

  22. Case 2 • 24 yr old male • ~ 1 yr Hx of headaches, worse last 2-3/12 • Examination: 6/6 OD 6/6 OS No RAPD Pallor + Pallor + • CT head – pituitary adenoma

  23. 39 year old: 6/6 VA both eyes Visual Fields – 2/7 pre-op

  24. Visual Acuity Pupil Testing Colour vision Visual Fields Fundus Examination

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