Forewarned is forearmed A retinal update Peter Simcock & Hirut von Lany

1. Forewarned is forearmedA retinal updatePeter Simcock & Hirut von Lany • OCT interpretation • What not to do with multifocal lenses • An audit of WEEU retinal referrals – when to refer and what to refer

2. OCT interpretation

3. A bit of confusing anatomy

4. Anatomy made simple • Neuro-retina • Potential sub-retinal space • Retinal Pigment epithelium • Choroid

5. Neuro-retina • Nerve fibre layer • 1.1 million fibres per eye • Ganglion cells • Bipolar cells • Rods and Cones (photoreceptors) • Convert light into electrical impulses to transmit to the brain • Most energy dependent tissue in body

6. Retinal pigment epithelium • Recycles material from rods and cones • Recycling needed to maintain efficient function • Contains pigment to stop internal reflections • Prevents “glare” inside the eye • Melanin pigment • Pumps water out of the neuro-retina and potential sub-retinal space to keep it “dry”

7. Choroid • Supply oxygen and glucose to photoreceptors and RPE • Highest blood flow per unit area of any tissue in the body • Look what happens when you faint • Retina is always working very hard!

8. Important terminology • Inner retina Nerve fibre layer Ganglion cells Bipolar cells Supplied by Central retinal artery • Outer retina RPE and photoreceptors Supplied by Choroid

9. RPE and photoreceptors must not part company – they act as a single unit

10. Principles of the OCT Non invasive Based on interferometry Interference between incident and reflected light Like doing a vertical biopsy of the retina Use laser light rather than knife! Good at showing swelling due to leakage FFA still needed for showing blockage of blood vessels

11. Optical coherence tomographyNormal anatomy

12. Retina pathology often in layers • Inner retina (retinal circulation) • Diabetic retinopathy • Retinal vein occlusion • Outer retina (choroidal circulation) • AMD • CSR

13. OCT pathology often in layers • Retinal surface (mechanical problems) • Vitreo-macular traction • Epiretinal membrane • Inner retina (retinal circulation) • Diabetic retinopathy • Retinal vein occlusion • Outer retina (choroidal circulation) • AMD • CSR

14. Retinal pathology in more than one layer • Full thickness macular hole • All layers involved • Lamellar hole • Usually surface and inner retina • Severe retinal disease • Wet AMD (starts in outer retina) • Diabetic eye disease (starts in inner retina) • Retinal vein occlusions (starts in inner retina)

15. Central macular thickness • Normal thickness = 200 microns • Thick retina > 250 microns • Usually due to leakage • Thin retina < 150 microns • Atrophic with poor function • Can be difficult to assess function on thickness alone

16. The Ellipsoid • Junction between inner and outer segments • Barely visible in histological sections • Highly prominent with OCT • Due to difference in index of refraction of the inner and outer segments • Also called the photoreceptor integrity line • Used to be called the IS/ OS junction

17. Assess retinal function • Normal thickness retina – how is it functioning? • Well demarcated IS/OS junction suggest good photoreceptor function

18. Vitreo-macular traction • Terminology • Vitreo-retina adhesion – attached but not pulling • Vitreo-macular traction – attached and pulling) • If incidental OCT finding and patient asymptomatic – do not refer

19. Mild Vitreo-macular traction Inner retinal cyst 0.12 LogMAR

20. Severe Vitreo-macular traction 0.5 LogMAR “Pointed - being Pulled”

21. Epiretinal membrane • Posterior vitreous usually detached • Sometimes associated with lamellar hole • Wide range of severity • If incidental OCT finding and patient asymptomatic – do not refer

22. Mild epiretinal membrane 0.1 LogMAR Loss of foveal pit

23. Epiretinal membrane

24. ERM with saw tooth sign Note healthy ellipsoid Visual acuity is 0.12 No symptoms

25. ERM with lamellar macular hole Note healthy ellipsoid Visual acuity is 0.12 No symptoms

26. Full thickness macular hole

27. Spontaneous improvement in a full thickness macular hole

28. OCT and dry AMD Drusen “Lumpy bumpy” RPE

29. OCT and dry AMD RPE atrophy High signal beneath RPE Thin retina

30. Wet AMD • Abnormal blood vessels grow upwards from Choroid into Retina (Choroidal neovascular membrane) • May remain under the RPE “Occult” • May grow through RPE into neuro-retina “Classic”

31. retina RPE choroid Occult CNV

32. Retina RPE Choroid Classic CNV

33. Classic CNV – “ring of fire”

34. Damage to vision • Classic • Disrupts RPE / photoreceptor partnership • More aggressive process • Significant and rapid visual loss • Occult • RPE / photoreceptor partnership remains intact • May maintain better vision “low grade occult”

35. OCT and wet AMD • Outer retina first involved (choroidal circulation) • Fluid • Sub RPE • Sub Retinal • Intra retinal if severe • Usually previous dry AMD • Look at RPE line as rarely “pristine”

36. OCT and wet AMD Sub RPE fluid Sub retinal fluid Intra retinal fluid Note previous dry changes

37. “Burnt out” Wet AMD Disciform Scarring

38. What is RAP? • Choroidal neovascular membrane (CNV) are abnormal blood vessels growing upwards from Choroid into Retina (Occult and Classic) • Retinal angiomatous proliferations (RAP) are abnormal blood vessels growing downwards from Retina into Choroid • 15% of wet AMD is RAP and 100% bilateral within 3 years

39. RAP • Multiple intraretinal haemorrhages at macular • Can look like macular branch retinal vein occlusion but does not stop at horizontal midline

41. OCT and leakage • Wet AMD • Diabetic maculopathy • Retinal vein occlusions • CSR • Uveitis • Retinitis pigmentosa

42. Intraretinal fluid

43. Sub-retinal fluid

44. Sub-RPE fluid (PED)

45. Do not forget to look for retinal thickening • Interstitial fluid present • No discrete accumulations of fluid • Still an important sign of leakage

46. Do not forget to look for outer retinal hyper-reflectivity • Lipofuscin deposition • Active CNV tissue • Scarring • Look for other OCT and clinical signs to help determine what it is.

47. OCT and exudative diabetic maculopathy • Inner retina first involved (retinal circulation) • Fluid • Intra retinal (including cystoid oedema) • Sub retinal if severe • No Sub RPE fluid • Hard exudates • Highly reflective intraretinal spots • RPE looks ok

48. OCT and exudative diabetic maculopathy

49. OCT and retinal vein occlusions • Inner retina first involved (retinal circulation) • Fluid • Intra retinal (including cystoid oedema) • Sub retinal if severe • No Sub RPE fluid • Hard exudates • Less frequently seen than in diabetics • RPE looks ok

50. Ozurdex in macular oedema from central vein occlusion 0.5 LogMAR Pre injection 0.3 LogMAR Post injection