This document provides guidance on interpreting optical coherence tomography (OCT) scans of the retina. It begins by outlining key principles, such as utilizing fundus images and understanding the significance of OCT findings. It then details a 5-step process for evaluating scans: 1) assessing scan quality, 2) rating the overall retinal profile, 3) evaluating the foveal profile, 4) identifying any foveal cut, and 5) carrying out a structural assessment. This includes observing layer alterations, identifying additional structures, and using standardized terminology to describe pathological features. Key pathological structures and findings are defined, including changes affecting the retinal pigment epithelium, sub-RPE space, and intraretinal and subretinal spaces.

1. Interpretation and Terminology
of OCT for Retina
Christopher Mody Clinical
Programme Manager
Heidelberg Engineering Ltd

2.  Make valued judgements whilst scanning
 Utilise the fundus reference image
 Understand the significance OCT image
 Identify pathology & link to visual
symptoms

3. 30° high resolution line scan
Fovea
Inf

4. Dark regions :
• Intra retinal fluid
• Sub retinal fluid
• Sub RPE fluid
• Retinal elevation
IR fundus reference image

5. Green areas :
• Intra retinal fluid
• Sub retinal fluid
• Sub RPE fluid
• Retinal elevation
MultiColor fundus reference image

6. Blue laser FAF reference image
Dark regions:
• Retinal atrophy
• RPE atrophy
Bright regions:
• Active disease

7. Normal OCT

8.  What does the SD-OCT image actually
represent?

9. N T
Fovea
Internal Limiting Membrane
Retinal Blood Vessels

10. RNFL
Ganglion Cell Layer
Inner Plexiform Layer
Inner Nuclear Layer
Outer Plexiform Layer
Outer Nuclear Layer
External Limiting Membrane

11. Henle fibre layer

18. Choroid
Inner photoreceptor segments
Inner/outer photoreceptor junction
Rod/cone outer segments
RPE interdigitation
Bruch’s/RPE Complex

19. Pre-Euretina Normal OCT Classification
Formed Vitreous
Posterior Cortical Vitreous
Preretinal Space
Nerve Fiber Layer
Ganglion Cell Layer
Inner Plexiform Layer
Inner Nuclear Layer
Outer Plexiform Layer (dendritic)
Henle’s-ONL
junction (subtle)
Henle Fiber Layer (axonal OPL)
Outer Nuclear Layer
Sattler’s Layer (inner Choroid)
Haller’s Layer (Outer Choroid)
External Limiting Membrane
Ellipsoid Zone
Outer Segments
Interdigitation Zone
Choriocapillaris
RPE/ Bruch’s
Complex
Myoid Zone
Choroid
Sclera
Junction

20. Rods & Cones
OS
EZ
MZ
ELM
ONL
OPL
IZ
RPE

21. Inner segment
 Ellipsoid zone
 Mitochondria
 ATP production – chemical energy
 Myoid zone
 Golgi apparatus
 Protein synthesis
Ellipsoid zone
Myoid zone

22. Evaluating OCT images
1. Determine scan quality
2. Rate overall scan profile
3. Evaluate foveal profile
4. Identify foveal cut
5. Carry out structured assessment
 Observe alteration of layers
 Identify additional structures
 Pre retinal
 Epiretinal
 Intraretinal
 Subretinal
 Sub RPE

23. STEP 1
Determine overall scan quality

24.  Scan quality
Qualitative assessment

25. Qualitative assessment
Step 1
 Scan quality
 Identify inner and outer retinal band
 Good signal to noise ratio
 Truncated
 Shadowing

26. Vitreous opacities

27. Vessel shadowing

28. STEP 2
Rate the overall scan profile

29. Qualitative assessment
Step 2. Rate the over-all retinal scan profile
 The normal over-all retinal profile has a slightly
concave curvature.
 Abnormal profiles would include exaggerated
concavity and convexity or retinal folds.

30. The over-all retinal profile
 RPE detachment
 Fibrotic/Serous
 Haemorrhagic
 Retinal detachment
 Rhegmatogenous
 Serous
 Retinal thickening
 CSMO/CMO/CNV

31. STEP 3
Evaluate the foveal profile

32. Qualitative assessment
 Step 3. Evaluate the foveal profile
 The normal foveal profile is a slight
depression in the surface of the retina.

33. Foveal profile
 Deformations in the foveal profile include the following:
1. Macular pucker
2. Macular pseudo-hole
3. Macular lamellar hole
4. Macular cyst
5. Macular hole, stage 1 (no depression, cyst present)
6. Macular hole, stage 2 (partial rupture of retina, increased thickness)
7. Macular hole, stage 3 (hole extends to RPE, increased thickness, some
fluid)
8. Macular hole, stage 4 (complete hole, oedema at margins, complete
PVD)

34. STEP 4
Identify foveal cut

35. Fovea
Do you have a foveal cut?

36. STEP 5
Carry out a structural assessment

37. Qualitative Assessment
Step 5. Carry out a structural assessment
a) Observe alteration of layers
b) Identify additional structures
• Pre-retinal
• Epiretinal
• Intra-retinal
• Sub-retinal
• Sub RPE

38. Qualitative assessment
Pre-retinal
Epiretintal
Intra-retinal
Sub-retinal
• Sub neurosensory retina
• Sub RPE

39. Qualitative assessment
 Pre retinal – vitreous cavity:
1. pre-retinal membrane
2. epi-retinal membrane
3. vitreo-retinal strands
4. vitreo-retinal traction
5. syneresis
6. pre-retinal neovascular membrane NVE
7. pre-papillary neovascular membrane NVD

40. Qualitative assessment
 Pre-retinal
 A normal pre-retinal profile is displayed as
a black or white space.
 Prepapilla/prefoveal lacunae (premacula
bursa) may be visible

42. Qualitative assessment
 Intra-retinal changes:
1. Choroidal neovascularization
2. Diffuse intra-retinal oedema
3. Cystoid macular oedema
4. Hard exudates
5. Scar tissue
6. Atrophic degeneration

43. Qualitative assessment
 Sub-retinal/RPE:
1. choroidal neovascularization
2. RPE detachment
3. Drusen
4. sub-retinal fibrosis
5. scar tissue
6. RPE atrophy

44. What to look for…
1. Determine scan quality
2. Rate overall scan profile
3. Evaluate foveal profile
4. Identify foveal cut
5. Carry out structured assessment
 Observe alteration of layers
 Identify additional structures
 Pre retinal
 Epiretinal
 Intraretinal
 Subretinal
 Sub RPE

45. TERMINOLOGY

46. Irregularity
Fragmentation
Rupture
Interruption
Depression
Elevation
Thinning
Thickening
Alteration of Layers
Terminology

47. Irregularity
Fragmentation
Rupture
Interruption
Depression
Elevation
Thinning
Thickening
RPE
Terminology

48. Irregularity
Fragmentation
Rupture
Interruption
Depression
Elevation
Thinning
Thickening
RPE
Terminology

49. Irregularity
Fragmentation
Rupture
Interruption
Depression
Elevation
Thinning
Thickening
RPE
Terminology

50. Irregularity
Fragmentation
Rupture
Interruption
Depression
Elevation
Thinning
Thickening
RPE
Terminology

51. Irregularity
Fragmentation
Rupture
Interruption
Depression
Elevation
Thinning
Thickening
RPE
Terminology

52. Irregularity
Fragmentation
Rupture
Interruption
Depression
Elevation
Thinning
Thickening
RPE
Terminology

53. Additional
Structures
Macular Hole
Epiretinal Membrane (ERM)
Drusen
Blood Component
Fluid /Edema
Non Exudative Spaces
Neovascularisation
Fibrosis
Lipid Precipitates
Hyperreflective Spots & Dense
Areas
Tubulations of Outer Retina
Tumours

54. Identify RPE
Examine
RPE
Examine
posterior to
RPE
Examine
anterior to
RPE
Systematic Procedure

55. RPE
• Irregularity
• Fragmentation
• Rupture
• Interruption
• Depression
• Elevation
• Thinning
• Thickening
Posterior to RPE
• PED
• Bruch’s Membrane
• Hyperreflectivity
(atrophy of RPE
vs. fibrosis)
• Hyporeflectivity
(screen effect)
Anterior to RPE
• Vitreous
• Retinal Thickness
• Foveal Depression
• Subretinal Fluid
• ELM
• Elipsoid Zone
• Hyperreflective
Spots
• Dense Areas
• Outer Nuclear
Layer
• Intraretinal Cysts
• Inner Retinal
Layers

56. Identify RPESystematic Procedure

57. Examine
RPE
One single elevation of RPE (PED)
Undulating (wavy) PED
No interruption
No thickening or thinning of RPE
Identify EPR

58. Identify RPE
Examine
RPE
Examine
posterior to
RPE
Sub-RPE Reflectivity moderate
Shadow at RPE / sub - RPE

59. Hyperreflective Zone in inner layers
Intraretinal Cysts (in 2 layers)
Increased retinal thickness
Large Hyperreflective Precipitates
Hyperreflective Punctiform Precipitates
Dense Areas anterior to RPE
Interruption of ELM & Elipsoid Zone
Identify RPE
Examine
RPE
Retinal Angiomatous Profliferation
(RAP)
Posterio
rto RPE
Examine
anterior to
RPE
Intra & subretinal fluid

60. Final thoughts…
 Know your chorio retinal anatomy
 Familiarise yourself with normal variation in OCT
recordings
 Adopt a systematic approach to evaluating OCT images
 Familiarise yourself with the aetiology of macular
disease
 Don’t forget vision, signs/symptoms, history and fundus
appearance

61. Questions…
Acknowledgements:
Evangelos Tsiroukis MD
Institut Català de Retina
Barcelona
Professor Yit Yang
Wolverhampton Eye
Infirmary