Faculty Bibliography

PURPOSE:The purposes of this study were to describe choroidal findings observed using optical coherence tomography with enhanced depth imaging (EDI-OCT) in eyes with birdshot chorioretinitis (BSCR) and to test the hypothesis that these findings are related to participant demographics, clinical characteristics, and treatment. METHODS:In a multicenter, cross-sectional study, 172 eyes of 86 individuals with BSCR underwent a standardized clinical evaluation, including defined protocols for EDI-OCT imaging, with macular and peripapillary volume scans. Choroidal findings were compared to demographic information, ophthalmic examination findings, and treatment history, using logistic regression models. EDI-OCT images were evaluated by two independent, masked graders. RESULTS:Median age was 56 years old; 54 participants (62.8%) were female. One or more choroidal lesions (a predefined hyporeflective zone) were identified in 105 eyes (63.6%). Median choroidal thickness was 293 μm. Choroidal lesions were associated with longer disease durations (odds ratio [OR]: 1.08; P = 0.03), increased vitreous haze (>0.5+; OR: 4.43; P = 0.02), presence of macular edema (OR: 3.00; P = 0.02), and thick choroids (OR: 3.89; P = 0.001). Use of immunomodulatory therapy was associated with lower risk of thin choroids (lower 25th percentile, OR: 0.17; P = 0.001) or thick choroids (upper 25th percentile, OR: 0.22; P = 0.002). At least some choroidal lesions did not have corresponding, clinically apparent "birdshot lesions" on fundus examination. CONCLUSIONS:Choroidal abnormalities identified by EDI-OCT imaging are common in the macular and peripapillary regions of eyes with BSCR. Choroidal lesions were associated with clinical signs of inflammation, suggesting that they represent foci of disease activity. EDI-OCT may provide useful information about disease mechanisms and response to treatment in future, longitudinal studies of BSCR.

PURPOSE/OBJECTIVE:To inform the interpretation of clinical optical coherence tomography and fundus autofluorescence imaging in geographic atrophy (GA) of age-related macular degeneration by determining the distribution of retinal pigment epithelium (RPE) phenotypes in the transition from health to atrophy in donor eyes. METHODS:In RPE-Bruch membrane flat mounts of two GA eyes, the terminations of organized RPE cytoskeleton and autofluorescent material were compared. In high-resolution histological sections of 13 GA eyes, RPE phenotypes were assessed at ±500 and ±100 μm from the descent of the external limiting membrane (ELM) toward Bruch membrane. The ELM descent was defined as curved, reflected, or oblique in shape. Thicknesses of RPE, basal laminar deposit (BLamD), and RPE plus BLamD were measured. RESULTS:A border of atrophy that can be precisely delimited is the ELM descent, as opposed to the termination of the RPE layer itself, because of dissociated RPE in the atrophic area. Approaching the ELM descent, the percentage of abnormal RPE morphologies increases, the percentage of age-normal cells decreases, overall RPE thickens, and BLamD does not thin. The combination of RPE plus BLamD is 19.7% thicker at -100 μm from the ELM descent than that at -500 μm (23.1 ± 10.7 μm vs. 19.3 ± 8.2 μm; P = 0.05). CONCLUSION/CONCLUSIONS:The distribution of RPE phenotypes at the GA transition supports the idea that these morphologies represent defined stages of a degeneration sequence. The idea that RPE dysmorphia including rounding and stacking helps explain variable autofluorescence patterns in GA is supported. The ELM descent and RPE plus BLamD thickness profile may have utility as spectral domain optical coherence tomography metrics in clinical trials.

PURPOSE/OBJECTIVE:To investigate the retinal vascular findings and associated anatomic abnormalities in the central macula of eyes with diabetic retinopathy using volume-rendered angiographic and structural optical coherence tomography. STUDY DESIGN/METHODS:Observational case series. METHODS:In this retrospective study 25 eyes of 14 consecutive patients were imaged with optical coherence tomography (OCT) using split-spectrum amplitude decorrelation. The structural OCT data were segmented for cystoid spaces and integrated into the angiographic data for subsequent volume rendering. The opacity of various vascular layers could be decreased to improve visualization of deeper structures and the images could be rotated about 3 axes. The inner and deep vascular plexus were analyzed in relation to structural changes such as cystoid spaces and disorganization of the retinal inner layers. RESULTS:Retinal vascular flow abnormalities manifested by large flow voids in the inner vascular layer with retention of large vessels and confluent areas of flow loss in the deep plexus. Areas of cystoid edema were associated with topographically colocalizing flow voids in the deep vascular layer. In eyes with no edema isolated abnormalities of the deep plexus were associated with thinning of the inner nuclear layer and abnormalities of both layers were associated uniformly with the OCT findings of disorganization of the retinal inner layers. CONCLUSIONS:Widespread vascular abnormalities in diabetic retinopathy could be delineated along with the corresponding anatomic changes in the retina using volume-rendered angiographic and structural OCT. This method of imaging offers potential to improve visualization of vascular disorders of the eye.

PURPOSE/OBJECTIVE:To describe image artifacts of optical coherence tomography (OCT) angiography and their underlying causative mechanisms. To establish a common vocabulary for the artifacts observed. METHODS:The methods by which OCT angiography images are acquired, generated, and displayed are reviewed as are the mechanisms by which each or all of these methods can produce extraneous image information. A common set of terminology is proposed and used. RESULTS:Optical coherence tomography angiography uses motion contrast to image blood flow and thereby images the vasculature without the need for a contrast agent. Artifacts are very common and can arise from the OCT image acquisition, intrinsic characteristics of the eye, eye motion, image processing, and display strategies. Optical coherence tomography image acquisition for angiography takes more time than simple structural scans and necessitates trade-offs in flow resolution, scan quality, and speed. An important set of artifacts are projection artifacts in which images of blood vessels seem at erroneous locations. Image processing used for OCT angiography can alter vascular appearance through segmentation defects, and because of image display strategies can give false impressions of the density and location of vessels. Eye motion leads to discontinuities in displayed data. Optical coherence tomography angiography artifacts can be detected by interactive evaluation of the images. CONCLUSION/CONCLUSIONS:Image artifacts are common and can lead to incorrect interpretations of OCT angiography images. Because of the quantity of data available and the potential for artifacts, physician interaction in viewing the image data will be required, much like what happens in modern radiology practice.

PURPOSE/OBJECTIVE:To demonstrate combined and integrated volume rendering of the retinal vasculature and selected structural abnormalities information derived from optical coherence tomography. METHODS:The eyes were scanned using optical coherence tomography using split-spectrum amplitude-decorrelation techniques to derive flow information. Various sublayers could be color coded as needed. The corresponding structural optical coherence tomography information was segmented for salient anatomic structures of interest, such as areas of edema fluid or intraretinal lipid deposits. The angiographic and structural data were integrated on a plane-by-plane basis and used to create volume-rendered images. The combined volume-rendered angiographic and structural optical coherence tomography data could be rotated about three different axes for evaluation. RESULTS:Representative images from the eyes with diabetic macular edema, Type 1 macular telangiectasis, choroidal neovascularization, and retinal veno-occlusive disease are shown. The interrelationships between areas of cystoid fluid accumulation or intraretinal lipid accumulation could be visualized. CONCLUSION/CONCLUSIONS:Although structural and angiographic findings are typically shown in isolation, they can be integrated into a merged data set that is amenable to volume rendering. Using this new technique will allow investigation into the interrelationships between vascular and structural abnormalities of the retina and choroid.

PURPOSE: To use volume-rendered optical coherence tomography angiography to investigate vascular proliferation in macular telangiectasia type 2 (MacTel2), extending beyond the retinal pigment epithelium (RPE). METHODS: Six eyes of four patients with MacTel2 with neovascularization proliferating external to the RPE confines were studied. Eyes were scanned using optical coherence tomography using split-spectrum amplitude-decorrelation techniques to derive flow information (RTVue XR; Optovue). These data were extracted and used to create volume rendered images of the area of vascular proliferation. RESULTS: Mean age was 66.2 years. There was demonstrable vascular proliferation in the sub-RPE space observable by both optical coherence tomography and optical coherence tomography angiography. Fibrovascular RPE detachments were identified in all eyes. The topographic distribution of abnormal vessels located below the plane of the deep retinal vascular plexus and above the RPE closely matched the pattern of hyperfluorescence and leakage on fluorescein angiography. Vessels under the RPE demonstrated different branching patterns and larger diameter lumens than those above the RPE, but anastomosis with the choroidal circulation was difficult to demonstrate. CONCLUSION: This study provides evidence that sub-RPE vascular proliferation may be a complication of MacTel2. Retinal pigment epithelium abnormalities are known to occur in MacTel2 and may provide a conduit for abnormal vessels in the subretinal space to proliferate into the sub-RPE compartment. The authors have no reason to exclude the possibility that the choroid contributes to the deep proliferation.

PURPOSE: Macular pigments are preferentially concentrated in the central fovea, an area devoid of vasculature. We hypothesized that there may be a link between the macular pigment profile and the size and structural characteristics of the foveal avascular zone (FAZ). METHODS: Two-wavelength autofluorescence method was used to quantify macular pigment optical density (MPOD) and the radius at half peak of MPOD, which was defined as the retinal eccentricity where the MPOD value was 50% of the peak value. Volumetric spectral-domain optical coherence tomography (OCT) images of the macula were obtained from 32 subjects. The equivalent radius of the FAZ was determined using data generated from OCT angiography. Generalized estimating equations were used to test the hypothesis that there are interrelationships among the central foveal thickness, peak MPOD, the radius at half peak of MPOD and the equivalent radius of the FAZ. RESULTS: The equivalent radius of the FAZ was highly correlated with the radius at half peak of MPOD (P < .001). The equivalent radius of the FAZ was a significant predictor for central foveal thickness (P < .001). The significant predictor for peak MPOD was central foveal thickness (P = .004). Eyes with larger FAZs were more likely to have a secondary peak in their MPOD spatial profile in a zone ranging from 0.5 to 1.0 degrees from the foveal center. CONCLUSIONS: The spatial distribution of macular pigment is related to the size of the FAZ, in addition to the central foveal thickness. It is possible that xanthophyll pigment accumulation in the macula serves functions, such as attenuation of shorter wavelengths of light, that would have been provided by the light-filtering characteristics of blood vessels.