Optical coherence tomography is indispensable for retina care delivery in the United States. Wait, you think to yourself, my 78-diopter exam is pretty good!
To quickly be reminded how desperately we need OCT to complement our examinations in order to accurately diagnose and manage our patients, try examining a few new patients before you look at their OCT.
The first commercial units were released 26 years ago, and since then the hardware and software functionalities have advanced tremendously. Currently, most clinical units use spectral-domain technology with resolution of up to 2 µm, representing 1/50th the diameter of a strand of hair, or one-quarter the width of an erythrocyte. Repeated scanning over short periods enables OCT-angiography, which is slowly being incorporated into routine practice.
Most commonly, we utilize OCT to determine the presence, absence or change in fluid status associated with exudative retinal diseases. But, the utility of OCT extends far beyond management of these common causes of blindness. We identify nonexudative macular neovascular lesions, hunt for subtle fundings suggestive of photoreceptor dysfunction and assess vitreous status and choroidal thickness in order to inform accurate diagnoses, to name just a few additional uses.
Descriptions of OCT findings have exploded into an alphabet-soup of clinically relevant acronyms (FCE, ORT, PAMM, AMN, SIRE, etc.) and graphic metaphors of imaging patterns (flying saucer sign, pearl necklace sign, cotton ball sign, etc.). Please see Dr. Caroline Baumal’s and Dr. Dilraj Grewal’s pieces for excellent summaries of important and more nuanced OCT findings on pages 18 and 23.
Despite our obsession with OCT, it’s notable that the Food and Drug Administration has not accepted any OCT findings as approvable clinical trial endpoints for new therapeutics. So far, visual outcomes are the primary basis for FDA approval, although a precedence for anatomic endpoints is emerging.
For example, score changes on the Diabetic Retinopathy Severity Scale have led to approvals for diabetic retinopathy. Looking ahead, we may have our first approved therapeutic for geographic atrophy in the coming months, based on anatomic assessment through longitudinal fundus autofluorescence changes.
Consistent with the FDA emphasis on vision, as important as OCT is to us, we must hear our patients when they repeatedly direct us back to function. Our patients want to see better today and tomorrow, with as few interventions as possible. We must continue aspiring to connect our OCT biomarkers with functional, prognostic or diagnostic relevance in order to guide better care for our patients. RS