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PURPOSE To study the three-dimensional morphologic features of retinal arteriovenous crossings with optical coherence tomography (OCT) and elucidate the vascular changes associated with crossing phenomena as seen on fundus photographs. METHODS We examined 150 consecutive eyes with no ocular disease. In each eye, fundus photographs were taken, and one randomly selected arteriovenous crossing was examined by OCT. The OCT analysis was performed by using sequential thin sections along and perpendicular to the retinal vessels. RESULTS The OCT analysis of these arteriovenous crossings showed that the veins abruptly changed their directions to pass the artery and frequently displayed focal luminal narrowing with no compression or flattening. The OCT measurements revealed that the veins narrowed by 21.0% ± 12.9% at the crossings. The degree of narrowing correlated positively with the diameter of the crossing arteries (r = 0.419, P < 0.001). On fundus photographs, crossing phenomena were observed in 103 of the 150 selected crossings. Venous narrowing measured by OCT was more severe in eyes with crossing phenomena on fundus photographs (P < 0.001). Four types of crossing phenomena were observed: concealment, tapering, deflection, and humping. Venous narrowing rates were similar among all four types. Although the subjects with deflection or humping phenomena were more likely to suffer from hypertension, the mean venous narrowing rate at such crossings was similar to that observed with the other crossing phenomena. CONCLUSIONS Arteriovenous crossings exhibited focal narrowing of the venous lumen with no compression or flattening. Increased venous narrowing and larger arteries were observed at crossings with crossing phenomena.

PURPOSE We studied morphologic changes of the retinal vasculature in eyes with central retinal vein occlusion (CRVO) through the use of optical coherence tomography (OCT). METHODS Major retinal vessels in 35 eyes from 35 consecutive patients with acute CRVO were examined prospectively and longitudinally with sequential thin sectioning and circumpapillary scanning. Anteroposterior venous tortuosity associated with CRVO was quantified on longitudinal OCT images of a randomly selected major temporal vein. On OCT sections of a given vein, we identified the innermost and outermost points of the vessel wall. The degree of anteroposterior venous tortuosity was defined as the difference between the vertical distances from the retinal pigment epithelium to the center of the venous lumen at these two points. RESULTS The OCT images revealed that the major retinal veins traveled tortuously through the swollen neurosensory retina from the inner retinal surface to the retinal pigment epithelium. The degree of anteroposterior venous tortuosity was correlated with poor visual acuity (r = 0.457, P = 0.017), increased mean foveal thickness (r = 0.671, P < 0.001), and the height of foveal detachment (r = 0.414, P = 0.032). In 4 (11%) eyes, a localized retinal detachment was detected around the optic disc, which correlated with anteroposterior venous tortuosity. In 14 (40%) eyes, elongated major retinal veins disrupted the boundary between retinal vessels and parenchyma, which resulted in juxtavenous splitting of the neurosensory retina. CONCLUSIONS In eyes with CRVO, OCT can be used to visualize anteroposterior venous tortuosity and associated structural changes to the retinal parenchyma.

[Purpose]To validate and evaluate the reliability of retinal vessel diameter measurements by optical coherence tomography (OCT). The effects of age and hypertension on vessel diameter were also examined. [Design]Prospective, cross-sectional study. [Methods]Two hundred thirty-eight eyes (238 subjects) with no ocular disease were included. Hypertension was present in 106 subjects and absent in 132 subjects. Spectralis HRA+OCT was used to scan a circular region around the optic disc. Outer and inner diameters of the 4 largest retinal arteries and veins were measured using OCT vascular wall reflections, and vessel wall thickness was calculated. [Results]Intervisit, interexaminer, and interevaluator intraclass correlation coefficients of randomly selected vessel measurements were all greater than 0.90. Mean inner arterial and venous diameters were 87.8 ± 9.4 μm and 113.7 ± 12.5 μm, respectively. The OCT-measured mean inner arterial and venous diameters were significantly correlated to fundus photography caliber measurements (P = .005 and P = .001, respectively). Arterial and venous wall thicknesses were 17.4 ± 2.4 μm and 13.7 ± 2.1 μm, respectively, both of which were highly correlated with subject age (arterial: r = 0.612, P < .001, venous: r = 0.455, P < .001). Additionally, both mean arterial and venous wall thicknesses were significantly greater in subjects with hypertension than in age-matched subjects without hypertension (P = .020 and P = .015, respectively). [Conclusions]Retinal vessel diameter measurements obtained with OCT were highly reproducible and vessel wall thicknesses, calculated using outer and inner diameter measurements, were significantly thickened by both aging and systemic hypertension.

PURPOSE To investigate the relationship between the cystoid spaces in the outer plexiform layer (OPL) and the characteristics of the photoreceptors beneath the cystoid spaces in patients with diabetic macular edema (DME). METHODS In this observational cross-sectional study, 123 eyes of 96 consecutive patients with clinically significant macular edema were retrospectively reviewed. The characteristics of the photoreceptors on optical coherence tomography (OCT) images represented by the external limiting membrane (ELM) and the junction between inner and outer segments (IS/OS), and their association with the overlying cystoid spaces were investigated. RESULTS The areas beneath the cystoid spaces in the OPL had a longer transverse length of disrupted or faint IS/OS and disrupted ELM lines than those without cystoid spaces (P < 0.001, P < 0.001, and P = 0.009). The IS/OS lines beneath the cystoid spaces had higher reflectivity than those in areas without cystoid spaces (P < 0.001). Enlarged cystoid spaces extending from the inner nuclear layer to the OPL were associated with disrupted IS/OS or ELM but not faint IS/OS (P < 0.001, P < 0.001, and P = 0.467). The transverse length of disrupted IS/OS at the fovea was correlated with the logarithm of the minimum angle of resolution (logMAR) more than the association between foveal thickness and logMAR (r = 0.49, P < 0.001 vs. r = 0.28, P = 0.002). The ELM descended to the RPE more frequently in eyes with single-lobulated fluorescein pooling in the foveal avascular zone than those with multi-lobulated pooling (P < 0.001). CONCLUSIONS OCT showed that the cystoid spaces in the OPL were accompanied by photoreceptor damage beneath the cystoid spaces in DME.

PURPOSE To study the usefulness of focal macular electroretinography (fmERG) for evaluation of macular function in eyes with macular edema (ME) associated with branch retinal vein occlusion (BRVO). METHODS The authors prospectively performed fmERG on 34 patients with untreated unilateral BRVO at the initial visit and 12 months later. Amplitudes and latencies of the a-wave, b-wave, and photopic negative response (PhNR) were compared with visual acuity, with retinal sensitivity measured by microperimetry, and with measurements obtained by optical coherence tomography. RESULTS In eyes with ME from BRVO, amplitudes of the a-wave, b-wave, and PhNR were reduced significantly and latencies were prolonged significantly compared with those of healthy fellow eyes (P < 0.05). Relative amplitudes and latencies were not correlated with visual acuity but, rather, tended to be correlated with retinal sensitivity within the macular area. Among all parameters studied by fmERG, relative amplitude of the PhNR was most strongly correlated with central foveal thickness (r = -0.465; P = 0.007). In addition, the height of the serous retinal detachment showed a correlation with the relative amplitude of the PhNR (r = -0.376; P = 0.034). At 12 months, the amplitude of the b-wave and the PhNR improved significantly, in parallel with resolution of the ME (P = 0.015; P = 0.033). CONCLUSIONS In eyes with ME from BRVO, amplitudes and latencies seen by fmERG were correlated with other biological parameters. Based on findings of the present study, fmERG appears to be useful as a functional examination within the macular area affected by BRVO.