Abstract:We used a confocal adaptive optics scanning laser ophthalmoscope (AOSLO) to image the retina of subjects with nonproliferative diabetic retinopathy (NPDR). To improve visualization of different retinal features, the size and alignment of the confocal aperture were varied. The inner retinal layers contained clearly visualized retinal vessels. In diabetic subjects there was extensive capillary remodeling despite the subjects having only mild or moderate NPDR. Details of the retinal microvasculature were readily imaged with a larger confocal aperture. Hard exudates were observed with the AOSLO in all imaging modes. Photoreceptor layer images showed regions of bright cones and dark areas, corresponding in location to overlying vascular abnormalities and retinal edema. Clinically undetected intraretinal vessel remodeling and varying blood flow patterns were found. Perifoveal capillary diameters were larger in the diabetic subjects (p<0.01), and small arteriolar walls were thickened, based on wall to lumen measurements (p<.05). The results suggest that existing clinical classifications based on lower magnification clinical assessment may not adequately measure key vascular differences among individuals with NPDR.

Adaptive Optics (AO) retinal imaging has provided revolutionary tools to scientists and clinicians for studying retinal structure and function in the living eye. From animal models to clinical patients, AO imaging is changing the way scientists are approaching the study of the retina. By providing cellular and subcellular details without the need for histology, it is now possible to perform large scale studies as well as to understand how an individual retina changes over time. Because AO retinal imaging is non-invasive and when performed with near-IR wavelengths both safe and easily tolerated by patients, it holds promise for being incorporated into clinical trials providing cell specific approaches to monitoring diseases and therapeutic interventions. AO is being used to enhance the ability of OCT, fluorescence imaging, and reflectance imaging. By incorporating imaging that is sensitive to differences in the scattering properties of retinal tissue, it is especially sensitive to disease, which can drastically impact retinal tissue properties. This review examines human AO retinal imaging with a concentration on the use of the Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO). It first covers the background and the overall approaches to human AO retinal imaging, and the technology involved, and then concentrates on using AO retinal imaging to study the structure and function of the retina.

Our results show that retinal vascular mural cells and wall structure can be readily resolved in healthy subjects using AOSLO with multiply scattered light imaging for retinal vessels with a lumen diameter greater than or equal to 10 μm. Our noninvasive imaging approach allows direct assessment of the cellular structure of the vascular wall in vivo with potential applications in retinal vascular diseases such as diabetes and hypertension.

The angle of the raphe in the study was not consistent with classic raphe models. While the angle showed relatively large individual variability, there seems to be a systematic relation between the disc, fovea, and raphe. It may be useful for individualizing retinal measurement strategies with regard to perimetry.

Purpose To determine whether hard exudates (HE) within one disc diameter of the foveola is an acceptable criterion for the referral of diabetic patients suspected of clinically significant macular edema (CSME) in a screening setting. Methods 143 adults diagnosed with diabetes mellitus were imaged using a non-mydriatic digital fundus camera at the Alameda County Medical Center in Oakland, CA. Non-stereo fundus images were graded independently for the presence of HE near the center of the macula by two graders according to the EyePACS grading protocol. The patients also received a dilated fundus exam on a separate visit. CSME was determined during the dilated fundus examination using the criteria set forth by the Early Treatment Diabetic Retinopathy Study. Subsequently, the sensitivity and specificity of hard exudates within one disc diameter of the foveola in non-stereo digital images used as a surrogate for the detection of CSME diagnosed by live fundus examination were calculated. Results The mean age of 103 patients included in the analysis was 56±17years. CSME was diagnosed in 15.5% of eyes during the dilated exam. For the right eyes, the sensitivity of hard exudates within one disc diameter from the foveola as a surrogate for detecting CSME was 93.8% for each of the graders; the specificity was 88.5% and 85.1%. For the left eyes, the sensitivity was 93.8% and 75% for each of the two graders, respectively; the specificity was 87.4% for both graders. Conclusions This study supports the use of HE within a disk diameter of the center of the macula in non-stereo digital images for CSME detection in a screening setting.