Ordering and Interpreting OCT Imaging of the Jessica Haynes OD FAAO Charles Retina Institute [email protected]

1. Quick Tips a. View cross sectional scans in black and white instead of color i. Example of CSR patient with minor outer retinal findings easier to visual in black and white scan. ii. Example of patient with early CNV easier to visualize with black and white scan. b. Look through all scans, don't rely on thickness maps i. Example of two thickness maps with “red” areas. 1. One is diabetic , one is branch retinal artery occlusion. 2. Disease cannot be diagnosed by thickness map alone. ii. Equate OCT to MRI; patient would not be happy if their radiologist only looked at a few scans on a printout. 2. Ordering the correct scan a. Obtain a high definition, good quality scan (garbage in, garbage out) b. Scan position i. Centered on the fovea? ii. Centered on a particular lesion or location (Scanning outside the cube)? 1. Example 1 a. Scan oriented over retinal artery in patient with suspected hollenhorst plaque who had recently undergone vitrectomy for repair b. Hyper-reflective material present above the blood vessel was determined to be diamond dust from surgical instruments. c. Example of patient with actual hollenhorst plaque identified on OCT cross section 2. Example 2 a. Non-symptomatic 25-year-old female referred after annual contact examination for evaluation of . b. Appropriately placed scan confirms retinal detachment rather than retinoschisis. 3. Example 3 a. Asymptomatic optometry student presents for evaluation of retinal holes b. Peripheral OCT confirms significant accumulation of subretinal fluid associated with retinal holes c. Scan Orientation i. Horizontal ii. Vertical iii. Radial iv. Case examples 1. Example 1 a. Patient referred for evaluation of macular edema. Patient currently being treated with NSAID. b. Appropriate radial scan reveals that patient has full thickness macular hole. c. Patient managed surgically with good result. 2. Example 2 a. Choroidal folds more appropriately imaged with vertically oriented scans than with horizontally oriented scans. 3. Example 3 a. Patient referred for evaluation of macular edema. b. Patient diagnosed with pit maculopathy. Long raster scans encompassing the macula, peripapillary macula bundle, and more appropriately aid in the diagnosis of the patient. 4. Example 4 a. Patient with epimacular membrane and significant visual symptoms. b. Does our scan orientation provide full picture of patient’s visual disturbance? c. Extent of retinal disruption seen with en face OCT versus that seen with cross sectional OCT. d. Scan density e. With or without enhanced depth imaging? i. Example of useful EDI imaging in young patient with drusen, non-AMD diagnosis. Patient has healthy choroidal thickness. ii. Example where EDI is not needed in patient with released vitreomacular traction. Improved ability to image vitreous with non-EDI image. f. Do you need a scan that gives a thickness map? i. Thickness map example of patient with improved diabetic macular edema. ii. Thickness map example of patient with worsened diabetic macular edema. iii. Thickness maps may be used to improve patient education. g. Use clinical findings and patient symptoms to guide you. h. Instead of saying “Get me an OCT” use more specific terminology for technicians. 3. Understanding reflectivity a. OCT uses light energy to generate an image based on the reflectivity of light. Certain structures will be hypo-reflective and some will be hyper-reflective. b. Hypo-reflective structures i. Nuclear layers ii. Fluid iii. Anatomically empty space iv. Shadowing v. Others c. Hyper-reflective structures i. Plexiform layers ii. EMM iii. Exudate iv. Blood v. Vessel Walls vi. Vitreous opacities vii. Pigment migration viii. Disciform scar ix. Reverse Shadowing x. Others d. In isolation, a “hyper-reflective” dot on OCT could be many different things: pigment, vitreous hemorrhage, vitreous cell, exudate, blood vessel wall, etc. You must put the findings into context of full picture to determine what it is. i. What layer is it located in? ii. What additional findings are seen on the scan? iii. What clinical findings are present? iv. Additional diagnostic imaging? 4. Understanding Retinal Layers a. Retinal anatomy review b. Case examples (games) demonstrating importance of knowing and being cognizant of retinal layers c. Game 1: Where is the massive hemorrhage? i. Two patients referred for massive retinal hemorrhage ii. One patient has pre-retinal hemorrhage, one patient has subretinal hemorrhage iii. Different diagnosis, etiology, management, and referral urgencies. d. Game 2: What is this yellow stuff in the retina? i. Examples of patients with EMM, exudate, and drusen ii. Each finding occurs in different layer in the retina. e. Game 3: Why can’t my patient see? What layer(s) are missing? i. Missing nerve fiber layer post NA-AION ii. Missing inner retinal layers post CRAO iii. Missing outer retinal layers in patient with macular telangiectasia type 2 5. Looking Beyond the Retina a. Ability of OCT to image the vitreous i. The aging vitreous 1. Vitreous condensation/ 2. Posterior vitreous detachment 3. Vitreomacular adhesion/vitreomacular traction ii. Vitreous hemorrhage iii. Vitreous cells 1. Case example of toxoplasmosis clinical course with treatment iv. Retinal neovascularization extending into vitreous b. Ability of OCT to image the i. Choroidal nevi ii. Choroidal thickness 1. Choroidal thinning in 2. Pachychoroid in patient with central serous 3. Increased choroidal thickness in patient with active punctate inner choroidopathy 6. Putting It All Together a. Case examples of patients with multiple retinal conditions i. Branch vein occlusion and EMM ii. VMT and AMD iii. How to describe the OCT findings b. Case examples using OCT in conjunction with fundus findings, FAF, IVFA, etc i. Choroidal neovascular membranes 1. Occult or type 1 CNV a. Fundus appearance b. FA findings c. OCT findings 2. Classic or type 2 CNV a. Fundus appearance b. FA findings c. OCT findings 3. Type 1 CNV with Subretinal hemorrhage a. Difficulty in discerning hemorrhage on OCT (hyper- reflective material). Look at patient to see if it correlates with area of visible hemorrhage. ii. 1. Patient with seemingly minimal retinopathy presents with pre- retinal hemorrhage OS from retinal neovascularization. 2. Are there any subtle findings that may suggest more extensive retinopathy? 3. OD macular OCT shows localized area of inner retinal atrophy, consistent with capillary non-perfusion on fluorescein angiography. 4. Although macular scan has “no macular edema” it has subtle findings demonstrating diabetic damage.