Retinal axial motion analysis and implications for real-time correction in human retinal imaging

High-resolution ophthalmic imaging devices including spectral-domain and full-field optical coherence tomography (SDOCT and FFOCT) are adversely affected by the presence of continuous involuntary retinal axial motion. Here, we thoroughly quantify and characterize retinal axial motion with both high temporal resolution (200,000 A-scans/s) and high axial resolution (4.5 um), recorded over a typical data acquisition duration of 3 s with an SDOCT device over 14 subjects. We demonstrate that although breath-holding can help decrease large-and-slow drifts, it increases small-and-fast fluctuations, which is not ideal when motion compensation is desired. Finally, by simulating the action of an axial motion stabilization control loop, we show that a loop rate of 1.2 kHz is ideal to achieve 100% robust clinical in-vivo retinal imaging.

NEURODEGENERATION AS AN EARLY SIGN OF DIABETIC RETINOPATHY

Diabetic retinopathy is major cause of visual impairment and blindness in diabetic patients worldwide. The concept of diabetic retinopathy as vascular disease has established into not only microvascular complication but also neurodegeneration problems. Neurodegeneration plays an important role in pathogenesis of diabetic retinopathy. In fact, neuroretinal changes in diabetes can take place even before vasculopathy can be clinically detected. This condition is marked by accelerated loss of neurons due to apoptosis, particularly in the inner retinal layer. The characteristic of neurodegeneration can be detected through retinal imaging and electrodiagnostics. This review is very crucial, because identifying the pathophysiology of diabetic neurodegeneration better, we may be able to provide interventions using the appropriate therapy. We may also be able to utilize these diagnostic tools for early detections of diabetic retinopathy, thus preventing blindness due to diabetes.