Reading an OCT image- The Basics - Topcon · 2019. 10. 10. · OCT is able to see the intricate and...
Transcript of Reading an OCT image- The Basics - Topcon · 2019. 10. 10. · OCT is able to see the intricate and...
Reading an OCT image- The Basics
What we will cover
• How OCT works • Layers of the retina • 3D OCT Tips • Healthy retina architecture • Pathology • Q&A
Seeing better with OCT
Light passing through tissue is delayed before it is reflected back to the camera
Measurement of this ‘delay’ provides
cross-sectional information about the structure of the tissue
being imaged
OCT is able to see the intricate and delicate layers of the retina, optic nerve and other ocular tissues (e.g. the RPE).
OCT image of the retina
Topcon 3D OCT 1000 Image
Layers of the Retina
Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004
Layers of the Retina
Nerve Fibre Layer Ganglion Cell Layer Inner Plexiform Layer Inner Nuclear Layer Outer Plexiform Layer Outer Nuclear Layer Ex. Limiting Membrane Photoreceptor IS/OS
Retinal Pigment Epithelium
Topcon 3D OCT 2000 Image
3D OCT Tips
• Trade off of scanning area vs. image quality
• Typical Pre sets – 8.2 mm x 3 mm @ 1,024 x
32 b scans (better image) – 6 mm x 6 mm box @ 512
x 128 b scans (better coverage)
Scanning Protocol
Patient preparation
• Pupil size – Min pupil size is 3.7 mm – Slightly dilated pupils will improve OCT and fundus image
quality
• Dry cornea – A dry cornea will reduce the OCT image quality – Make sure that your technicians tell the patient to blink
before the capture procedure – Use drops if needed
• Fixation
Viewing Techniques
• View in Black and White to provide better contrast
• Use OCT image adjustment bar
Healthy Retinal Architecture
Healthy Retina Architecture
Nerve Fibre Layer Ganglion Cell Layer Inner Plexiform Layer Inner Nuclear Layer Outer Plexiform Layer Outer Nuclear Layer Ex. Limiting Membrane Photoreceptor IS/OS
Retinal Pigment Epithelium
Topcon 3D OCT 2000 Image
Healthy Retina Architecture
Topcon 3D OCT 1000 Image
Healthy Retina Architecture
Topcon 3D OCT 1000 Image
Pathology
Pathology
• Reported incidence of pathology detected with Topcon 3D OCT in a Lasik population during pre-treatment evaluation was 1.6%
• Typical pathologies – Epiretinal membrane – Drusen – Macular Edema – Hard Exudates – Macular Holes – Vitromacular Traction
Epiretinal Membrane
• Incidence is 6% of patients over 60 yrs*. • Appearance
– Rippling of ILM which can extend over the fovea resulting of the loss of the normal foveal contour.
*Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004
Epiretinal Membrane
Topcon 3D OCT 1000 Image
Epiretinal Membrane
Topcon 3D OCT 1000 Image
Epiretinal Membrane Case 2
Topcon 3D OCT 1000 Image
Epiretinal Membrane Case 3 with Pseudo Hole
Topcon 3D OCT 1000 Image
Drusen
• Reported incidence of drusen in patients 43 to 54 was 2.2% (soft) and 3.3% (large)*
• Appearance – Localized highly reflective area under Bruch’s membrane,
you may also see a slight flattening of the foveal contour.
*Source: Beaver Dam Eye Study Ophthalmology. 2003 Oct: 109 (10): 1767-79.
Drusen
Topcon 3D OCT 1000 Image
Drusen
*Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004
Drusen
*Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004
Drusen
Topcon 3D OCT 2000
Macular Edema
• Appearance – Hypo echoic areas in the retina. Can be associated with
Diabetes (Diabetic Macular Edema- DME), cystic in appearance (Cystoid Macular Edema- CME)
Macular Edema
Topcon 3D OCT 2000
CME
Topcon 3D OCT 1000 Image
Hard Exudates
• Can be seen in any conditions that are associated with vascular leakage – Diabetic retinopathy – Hypertensive retinopathy
• Appearance – Focal hyper echoic areas in the ONL
Hard Exudates
Topcon 3D OCT 1000 Image
Macular Holes
• Extremely rare in patients under except you can see in the case of trauma. Various types – Lamellar (partial macular hole) – Full thickness macular hole
• Appearance – Lamellar hole- pit/opening from ILM but not down to the RPE – Full thickness macular hole- Opening down to the RPE, volcano
appeareance
Macular Hole
*Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004
Macular Hole
Topcon 3D OCT 1000 Image
Vitromacular Traction (VMT)
• Extremely rare • Appearance
– Perifoveal vitreous detachment with focal adhesion to the fovea
VMT
Topcon 3D OCT 1000 Image
VMT
Topcon 3D OCT 1000 Image