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Objective: To compare baseline characteristics and treatment response of participants with hemiretinal vein occlusion (HRVO) with those of participants with branch retinal vein occlusion (BRVO) or central retinal vein occlusion (CRVO) in the Standard Care vs COrticosteroid for REtinal Vein Occlusion (SCORE) Study., Methods: Eyes were randomized to standard care, 1 mg intravitreal triamcinolone acetonide, or 4 mg intravitreal triamcinolone acetonide. Standard care was observation in the SCORE-CRVO trial and grid photocoagulation in the SCORE-BRVO trial. The HRVO eyes were enrolled in the SCORE-BRVO trial. Baseline characteristics, changes in visual acuity and center point thickness, safety outcomes, and number of treatments were compared among HRVO, BRVO, and CRVO participants., Results: At baseline, HRVO eyes were intermediate between BRVO and CRVO eyes in area of retinal thickening, area of fluorescein leakage, visual acuity, and center point thickness. No differences in visual acuity change from baseline to 1 year were noted between standard care groups for HRVO and BRVO. Within triamcinolone-treated eyes, HRVO eyes did not differ from BRVO eyes in visual acuity change, but HRVO eyes fared better than CRVO eyes. There were no differences in center point thickness change between standard care groups for HRVO and BRVO, nor were there differences across the 3 disease entities for triamcinolone-treated eyes. There were no differences in frequency of protocol treatments and adverse events., Conclusions: The HRVO participants were similar to BRVO and CRVO participants regarding most demographic characteristics, with fundus findings intermediate between BRVO and CRVO. In the SCORE Study, HRVO was treated as BRVO; HRVO eyes responded to treatment similarly to BRVO eyes, and there was no difference among the 3 disease entities in frequency of protocol treatments and adverse events., Trial Registration: clinicaltrials.gov Identifier: NCT00105027.

Objective: To describe the relationship of change in retinal vessel diameters to the subsequent 6-year incidence and progression of diabetic retinopathy (DR) and incidence of proliferative diabetic retinopathy (PDR) and macular edema (ME) in persons with diabetes mellitus., Design: A total of 1098 persons with diabetes who had DR graded from fundus photographs and had computer-assisted measurements of the central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent(CRVE) participated in examinations in 1980-1982, 1984-1986, and 1990-1992., Results: During the first 4-year period, the mean change in CRAE and CRVE was −0.37 and 2.54 μm, respectively.The 6-year incidence and progression of DR and the incidence of PDR and ME from 1984-1986 to 1990-1992 were 56%, 39%, 15%, and 11%, respectively. In multivariate analyses, while controlling for duration, diabetes type, and other factors, an increase of 10 μm in CRVE from 1980-1982 to 1984-1986 was associated with increases in the 6-year incidence of DR (odds ratio [OR],1.26; 95% CI, 1.10-1.43), progression of DR (OR, 1.21;95% CI, 1.12-1.30), incidence of PDR (OR, 1.19; 95%CI, 1.07-1.32), and incidence of ME (OR, 1.16; 95% CI,1.03-1.31). No interactions of these associations by diabetes type were found (data not shown). Change in CRAE was unrelated to the incidence or progression of DR (data not shown)., Conclusions: Independent of DR severity level, glycemic control, and other factors, widening of the retinal venular but not arteriolar diameter was associated with subsequent incidence and progression of DR. The CRVE may provide additional information regarding the risk of incidence and progression of DR beyond traditional risk factors.

Objective: To examine the relationship between retinal arteriolar and venular diameter and the 6-year incidence of cardiovascular disease and mortality among African Americans with type 1 diabetes mellitus., Methods: Included were 468 African Americans with type 1 diabetes mellitus who participated in the New Jersey 725 and who had undergone a 6-year follow-up examination. At both baseline and 6-year follow-up, hypertension and presence of heart disease, stroke, or lower extremity arterial disease (LEAD) were documented and confirmed by review of hospital admission and medical records. Computer-assisted grading from digitized images of retinal photographs was accomplished to determine the average diameter of retinal arterioles (central retinal arteriolar equivalent) and venules (central retinal venular equivalent). Retinal vessel diameter size was examined in relation to the 6-year incidence of hypertension, any cardiovascular disease (heart disease, stroke, or LEAD), heart disease or stroke, LEAD, and mortality., Results: Narrower central retinal arteriolar equivalent at baseline significantly and independently predicted 6-year incidence of any cardiovascular disease and LEAD, whereas larger retinal venular diameter at baseline significantly and independently predicted 6-year incidence of hypertension. Proteinuria and retinopathy severity at baseline were stronger predictors of mortality than retinal vascular diameter., Conclusion: In African Americans with type 1 diabetes mellitus, baseline retinal vessel caliber is an independent predictor of incident hypertension and LEAD.

Objective: To determine whether quantitative analysis of retinal vessel width and tortuosity from digital images discriminates which eyes with preplus retinopathy of prematurity (ROP) progress to treatment severity., Methods: Posterior pole images of eyes at first clinical diagnosis of preplus ROP were obtained using a 30 degrees-field, noncontact fundus camera. Width and tortuosity of retinal vessels were analyzed from digital images using computer-assisted image analysis software. Mean width and tortuosity of venules and arterioles were compared in 19 preplus eyes that regressed spontaneously and 11 preplus eyes that progressed to treatment severity. Receiver operating characteristic curve analysis was performed to assess whether width and tortuosity discriminated between groups., Results: Mean widths of venules alone, arterioles alone, and the 3 widest vessels were higher in preplus progressed eyes (P < .04). Mean tortuosity of the 3 most tortuous vessels was higher in preplus progressed than in preplus regressed eyes (P = .01). Most vessel width and tortuosity variables predicted which eyes with preplus progressed to treatment moderately well, with an area under the receiver operating characteristic curve of 0.72 to 0.82., Conclusions: Digital image analysis of retinal vessel width and tortuosity may be useful in predicting which preplus ROP eyes will require treatment. Because vascular abnormalities are a continuum and clinical diagnosis is subjective, quantitative analysis may improve risk stratification for ROP.

Objective: To examine the relative contributions of systemic cardiovascular factors to retinal arteriolar and venular caliber in men and women and in whites and African Americans., Methods: In the Atherosclerosis Risk in Communities study, retinal arteriolar caliber (central retinal arteriolar equivalent), and venular caliber (central retinal venular equivalent) were measured from digitized retinal photographs of 8794 participants., Results: The main systemic determinants of narrower central retinal arteriolar equivalent were, in order of relative decreasing contribution, higher current mean arterial blood pressure, lower serum albumin level, current alcohol consumption, and higher body mass index (calculated as weight in kilograms divided by height in meters squared). The main systemic determinants of wider central retinal venular equivalent were current cigarette smoking and higher current mean arterial blood pressure, followed by higher white blood cell count, body mass index, and plasma low-density lipoprotein cholesterol levels. These associations were generally similar in whites and African Americans and in men and women., Conclusions: The major systemic determinant of narrower retinal arteriolar caliber is higher blood pressure, while those of wider retinal venular caliber are cigarette smoking, higher blood pressure, systemic inflammation, and obesity. These data offer further insights into the systemic processes influencing arteriolar and venular characteristics and may help explain the observed associations of retinal vascular caliber and the risk of clinical cardiovascular disease.

Objective: To describe the relation of retinal arteriolar and venular caliber to the incidence and progression of diabetic retinopathy in people with type 1 diabetes mellitus., Design: Incidence findings in a population-based study of diabetic retinopathy in Wisconsin. Participants included 996 persons diagnosed as having diabetes mellitus before 30 years of age who took insulin and underwent the baseline examination, 891 in the 4-year follow-up, 765 in the 10-year follow-up, and 634 in the 14-year follow-up. Retinal photographs of 7 standard fields were taken at all examinations. Computer-assisted grading was performed from a digitized image of field 1 to determine the average diameter of retinal arterioles and venules and their ratio. Main outcome measures included incidence and progression of retinopathy, incidence of proliferative retinopathy, and macular edema., Results: While adjusting for other factors, larger arteriolar (relative risk [RR] for the fourth vs first quartile range, 2.04; 95% confidence interval [CI], 1.20-3.47; test of trend, P =.008) and venular diameters (RR, 2.33; 95% CI, 1.37-3.95; test of trend, P =.005) were associated with greater 4-year progression of retinopathy. Larger venular diameters (RR, 4.28; 95% CI, 1.50-12.19; test of trend, P =.006) but not arteriolar diameters were associated with greater 4-year incidence of proliferative retinopathy. In multivariable analyses, arteriolar and venular calibers were not associated with the 4-year incidence of retinopathy. While adjusting for other factors, arteriolar and venular calibers were not associated with incidence of macular edema at 4 years. There were few associations of arteriolar or venular caliber with the 10- or 14-year incidence or the progression of retinopathy., Conclusions: Larger arteriolar and venular caliber, independent of retinopathy severity level, is related to the progression of retinopathy, and larger venular caliber is associated with the 4-year incidence of proliferative retinopathy. Caliber of retinal vessels is not associated with incident retinopathy. These data suggest a quantitative measure of retinal vascular caliber provides additional information regarding risk for progression of retinopathy.

Objective: To investigate the significance of optic nerve head swelling (ONHS) in relation to the pattern of vascular nonperfusion, visual acuity (VA), and demographic profile in retinal venous occlusions (RVOs) occurring within the optic nerve., Methods: Cases of RVO occurring within the optic nerve were divided on the basis of the presence (105 cases) or absence (163 cases) of ONHS. This division was performed by examining the color stereo fundus photographs in conditions masked from other clinical parameters. Duration of symptoms before assessment, age, and sex distributions were compared. The vein involved was identified, and the occlusion was confirmed to have occurred within the optic nerve by observing that the vein pierced the lamina cribrosa as a dilated vein. Fluorescein angiographs were examined, and the extent of vascular nonperfusion in the macula and peripheral retina was quantified from grade 1 to grade 4. The extent of break in the perifoveal capillary arcade was graded as 0, less than or equal to 90 degrees, and greater than 90 degrees. Best-corrected VA was assessed using the Snellen chart., Results: The 2 groups were comparable in terms of the duration of the symptoms before examination. The mean age was significantly younger in the group with ONHS (58.3 vs 65.1 years, P<. 001). Age distribution by sex demonstrated a higher proportion of men younger than 50 years in the ONHS group (19.1% vs 8.6%, P =.01). The group without ONHS involved the papillary vein more frequently (31.3% vs 17.1%, P =.01). The respective proportions of grade 1, 2, 3, and 4 vascular nonperfusion in the macula were 90.5%, 9.5%, 0%, and 0% in the ONHS group, and 62.6%, 14.7%, 13.5%, and 9.2% in the group without ONHS (P<.001). The corresponding proportions for the peripheral retina were 90.4%, 8.7%, 0%, and 1.0% in the ONHS group, and 62.7%, 13.0%, 18.0%, and 6.2% in the group without ONHS (P<.001). In 64.6% of cases with ONHS and 42.9% of cases without, the perifoveal arcade was intact. A break greater than 90 degrees in the perifoveal arcade was present in 12.5% of cases with and 23.6% of cases without ONHS (P =.004). The median VA was significantly better in the ONHS group (6/24 vs 6/48, P =.005)., Conclusions: The RVOs occurring within the optic nerve can be subdivided into 2 distinct groups on the basis of ONHS. The presence of ONHS is associated with younger age, less severe vascular nonperfusion, and better VA. This is consistent with a retrocribrosal site of occlusion, which has access to the pial plexus that can provide collateral channels for retinal venous drainage.

Objective: To investigate whether children with optic nerve hypoplasia and pituitary hormone insufficiencies have specific ocular fundus characteristics that may facilitate early diagnosis and treatment., Design: From May 15, 1995, through December 15, 1997, 17 children (8 girls and 9 boys, aged 0.3 to 13 years) with optic nerve hypoplasia were referred to the Department of Pediatric Ophthalmology, Children's Hospital, Göteborg, Sweden, and divided into 2 groups dependent on the presence (n = 8) or absence (n = 9) of pituitary deficiency. Morphological characteristics of the ocular fundus were evaluated by digital image analysis of fundus photographs, and the morphological characteristics of the brain structures were studied by magnetic resonance imaging., Results: An isolated venous tortuosity noted among the children with optic nerve hypoplasia and endocrinopathy was the morphological ocular fundus variable that discriminated between the 2 groups of patients with optic nerve hypoplasia. Both groups of children demonstrated significantly reduced optic disc, cup, and neuroretinal rim area and few vascular branching points., Conclusion: Optic nerve hypoplasia with isolated tortuosity of the retinal veins may potentially help the ophthalmologist in identifying children who should undergo a thorough diagnostic workup of endocrine function.

Objective: To characterize a group of phakic patients with idiopathic intermediate uveitis as defined by vitritis, cystoid macular edema, and retinal periphlebitis., Design: Cross-sectional study., Participants: Nineteen phakic patients (35 eyes) with vitreous inflammation, cystoid macular edema, and/or retinal periphlebitis of unknown cause., Intervention: None., Main Outcome Measures: Best-corrected final visual acuities, standardized clinical examinations, photographic and fluorescein angiographic evaluations, and class I and II HLA analysis on all 19 patients., Results: Fifteen of the 19 patients were women. The mean age was 38 years, the mean follow-up was 104 months, and the mean duration of symptoms was 154 months. All 35 affected eyes had significant vitritis; 21 eyes (60%) had cystoid macular edema, 21 eyes (60%) had retinal periphlebitis. The median initial visual acuity was 20/30. The median final visual acuity was 20/20 with 32 (91%) of 35 eyes having 20/40 or better visual acuity at the final visit. No patient developed "snow-banks" or evidence of systemic disease, including multiple sclerosis or sarcoidosis, during the follow-up period. There were no statistically significant HLA associations in these patients compared with controls from another study from Iowa, but the Iowa phakic patients with cystoid macular edema did differ from the Iowa patients with pars-planitis at loci HLA-B8, HLA-B51, and HLA-DR2., Conclusions: We describe a disease entity of idiopathic intermediate uveitis that affects primarily young to middle-aged women and usually causes bilateral vitritis, cystoid macular edema, and retinal periphlebitis. Most patients retained good vision over a prolonged follow-up period. Multiple sequential examinations and HLA associations suggest that these conditions are distinct from other syndromes of intermediate uveitis, particularly parsplanitis.

Objective: To establish a communication between an obstructed retinal vein and the choroid by means of laser in eyes with nonischemic central or branch vein occlusion., Methods: Retrospective review identified eyes with nonischemic central or branch vein occlusion, and with decreasing or persistently decreased visual acuity of 20/100 or worse for 4 months or more before treatment, that received 1 or more sessions of laser photocoagulation to create a chorioretinal anastomosis., Results: Of 24 eyes with central vein occlusion, an anastomosis formed in 9 (38%) within 2 months after treatment, with visual improvement of 6 or more lines in 2 (8%) of 24 eyes, 1 to 3 lines in 5 (21%), and no improvement in 2 (8%). Of 6 eyes with branch vein occlusion, an anastomosis formed in 3 (50%) within 2 months after treatment, with visual improvement of 1 to 3 lines in 2 (33%) of 6 and no improvement in 1 (16%). No permanent, vision-limiting complications occurred during a mean follow-up of 13 months after the first treatment session or 8 months after the last session., Conclusions: Laser photocoagulation of a retinal vein and Bruch's membrane may create a chorioretinal anastomosis in some eyes with a nonischemic vein occlusion. Progression to an ischemic status may possibly be prevented with successful anastomosis formation. Marked visual improvement may occur. Treatment techniques to create reliably an anastomosis with subsequent visual improvement, while minimizing potential complications, continue to evolve.

Objective: To assess the temporal relations among retinal appearance, disruption of the blood-retinal barrier, clinical subgroup, disease course, and disruption of the blood-brain barrier in multiple sclerosis., Design: A 6-month prospective study involving monthly clinical ocular examinations, color fundus photography, fundus fluorescein angiograms, and magnetic resonance brain scans with gadolinium-diethylenetriamine-pentaacetic acid (Gd-DPTA) enhancement., Setting: University-based ophthalmology and neurology departments., Patients: Twenty-three patients with relapsing-remitting, primary-progressive, or secondary-progressive multiple sclerosis., Results: Retinal venous sheathing was seen in six patients. The appearances observed included focal venous sheathing, diffuse venous sheathing, sheathing centered on sites of arteriovenous crossover, and focal perivenous hemorrhage. Arteriolar sheathing was also observed in one patient. Venous leakage on fundus fluorescein angiogram was detected in three patients, all of whom also had sheathing. The following three patterns of disruption of the blood-retinal barrier were seen on fundus fluorescein angiogram: focal leakage, extensive leakage, and very late wall staining. In one patient, the leakage was transitory. No correlations were observed between ophthalmologic features and multiple sclerosis clinical subgroup, disease course, or the number of new (Gd-DTPA-enhancing) lesions on magnetic resonance imaging., Conclusions: Disruption of the blood-retinal barrier, like the more frequent disruption of the blood-brain barrier seen on magnetic resonance imaging, is often unrelated to clinical neurologic relapses and occurs with apparently similar frequency in different patients independent of clinical disease course.

Objective: To identify specific features of pigment epithelium detachments with limited hyperfluorescent lesions (hot spots)., Design: One hundred eighty-two consecutive patients (186 eyes) who had vascularized pigment epithelium detachments and recent onset of symptoms were examined with indocyanine green and fluorescein videoangiography using the scanning laser ophthalmoscope. The choroidal neovascularization complex and macular retinal vessels were studied. The natural history and the effect of laser treatment were evaluated., Results: Fifty-four eyes had hot spots on indocyanine green angiography. In 50 of these 54 eyes, the video analysis showed an anastomosis of one or more retinal vessels, with the choroidal neovascularization within the hot spot. One or two retinal veins or arteries or both filled with both dyes and were seen to enter into the hot spot. Results of indocyanine green-guided photocoagulation of the hot spot in 28 eyes were disappointing., Conclusion: Continuous recording of the early phases of fluorescein and indocyanine green angiography allowed identification of chorioretinal anastomoses in vascularized pigment epithelium detachments with hot spots at an early exudative stage of age-related macular degeneration in 50 (26.8%) of 186 eyes. The poor outcome of laser photocoagulation could be related not only to the development of an overlying pigment epithelium detachment, but also to the retinal and choroidal vascularization of the lesion.

Objective: To investigate the relationship of various retinal lesions to systemic hypertension in the population-based Beaver Dam Eye Study., Design: In this cross-sectional population-based study, blood pressure was measured using standardized protocols. Using standardized protocols, stereoscopic color fundus photographs were graded in a masked fashion to determine the presence of retinopathy (defined as retinal microaneurysms only, blot hemorrhages only, hemorrhages and/or microaneurysms, cotton-wool spots, hard exudates, intraretinal microvascular abnormalities, venous beading, and retinal new vessels), retinal arteriolar narrowing, and arteriovenous nicking., Participants: Subjects aged 43 through 84 years who lived in Beaver Dam, Wis, between 1987 and 1988 were examined between 1988 and 1990. People with diabetes or retinal vascular occlusions were excluded., Results: Retinopathy was present in 336 subjects (7.8%), arteriolar narrowing in 582 subjects (13.5%), and arteriovenous nicking in 95 subjects (2.2%) in the nondiabetic population. Hypertension was associated with increased frequency of retinopathy, arteriolar narrowing, and arteriovenous nicking. After adjusting for age, hypertension was associated with the presence of retinopathy (in men: relative risk [RR], 1.47; 95% confidence interval [CI], 1.10 to 1.96; in women: RR, 1.69; 95% CI, 1.26 to 2.27), arteriolar narrowing (in men: RR, 1.34; 95% CI, 1.03 to 1.74; in women: RR, 1.37; 95% CI, 1.14 to 1.64), and arteriovenous nicking (in men: RR, 1.87; 95% CI, 0.99 to 3.54; in women: RR, 1.65; 95% CI, 1.00 to 2.73). Retinopathy, arteriolar narrowing, and arteriovenous nicking were more frequent in those subjects whose blood pressure was elevated despite use of antihypertensive medications compared with those subjects whose blood pressure was controlled with antihypertensive medications or those who were normotensive., Conclusions: These data suggest that retinopathy and retinal arteriolar narrowing are common in people with hypertension. Further longitudinal study is necessary to evaluate the public health significance of these retinal lesions regarding possibly increased risk of renal and cardiovascular disease.

We studied a 43-year-old woman affected with pigmented paravenous retinochoroidal atrophy and her unaffected monozygotic twin. The affected twin had stable visual acuity (20/25), typical fundus findings, markedly constricted visual fields, abnormal color vision, and an abnormal electroretinogram, all consistent with pigmented paravenous retinochoroidal atrophy. Results of examinations and studies in her twin were entirely normal. Fingerprinting for DNA performed on the twins strongly supported monozygosity. Our findings suggest that either our patient did not inherit pigmented paravenous retinochoroidal atrophy or that an unusual (nonmendelian) genetic mechanism occurred.

A male infant with a fatal case of Reye's syndrome had numerous intraretinal hemorrhages and hemorrhagic schisis blebs under the internal limiting membrane (ILM). Histopathologic examination showed bilateral central retinal vein thrombosis with recanalization and confirmed the presence of intraretinal hemorrhages and the sub-ILM schisis cavities. Ghost erythrocytes were demonstrated in the cavities by electron microscopy. Central retinal vein occlusion, to our knowledge, is a previously unreported complication of Reye's syndrome. Four other pairs of autopsy eyes from the Wilmer Eye Pathology Laboratory files of patients with Reye's syndrome were examined. These are compared with previously reported ophthalmic findings in the context of a general review of Reye's syndrome.

The incidence of clinically apparent retinal changes in 35 anemic patients and 35 age- and sex-matched control subjects was studied. Retinal photographs of all subjects were obtained. From these, all vascular and extravascular retinal lesions were noted. No retinal abnormalities were observed in the control subjects. Seven (20%) of the anemic patients exhibited extravascular lesions. There was no relationship detected between the occurrence of these changes and the severity or the cause of the anemia. Employing the assumption that true venous length for a given net distance traveled correlates with the degree of venous tortuosity, venous length over a standard radial distance from the optic disc was assessed with a curvometer. A significant negative correlation was determined between venous length and the level of hematocrit, thereby implying that retinal venous tortuosity is directly related to severity of anemia.

Alterations in retinal blood flow during the progression of diabetic retinopathy were studied using the dye-dilution technique. Mean fluorescein circulation times were measured in retinal arteriovenous segments with a two-point fluorophotometer in 48 diabetic patients and 20 normal controls. Monochromatic fundus photographs were used to determine vessel diameters. Segmental blood flow (SBF) increased with the progression of background diabetic retinopathy. In patients with distinct capillary closure, SBF was significantly higher than normal values.

The ocular clinicopathologic features of this unique patient were congenital stationary night blindness, drusen of the optic nerve head, cilioretinal artery, intraretinal pigmented lesion, and branch retinal vein occlusion. Photocoagulation therapy led to total disappearance of the neovascular tissue, clinically and histopathologically. Histopathologic examination showed an occluded branch vein associated with a sclerotic retinal arteriole. Peripheral to the site of venous occlusion, inner ischemic retinal atrophy was present. The normal complement of rod and cone photoreceptors supports the view that the night blindness in this case was an abnormality in the neural transmission and not on a morphological basis. The pigmented intraretinal lesion proved to be a localized area of retinal and choroidal neovascularization with anastomosis and secondary retinal pigment epithelial hyperplasia. This lesion was identical to Fuchs' dot of myopia but out patient was hyperopic.

We describe three cases of shallow posterior rhegmatogenous retinal detachment caused by tiny retinal tears. The clinical appearance of the detachments was very similar to that of idiopathic central serous chorioretinopathy or traction retinal detachment. However, the correct diagnosis was made by finding a tiny paravascular break. Vitrectomy without a thermal adhesion was successful in repairing the detachments.

We examined 11 young patients with unilateral ocular findings that included multiple white dots at the level of the retinal pigment epithelium (RPE) or the deep retina, vitreal cells, RPE granularity in the macula, reduced visual acuity, electroretinogram (ERG) and early receptor potential (ERP) amplitudes, and fluorescein leakage from disc capillaries and late staining of the RPE. Recovery of visual function included a dramatic improvement in ERG and ERP amplitudes over several weeks. The etiology of this syndrome remains uncertain; there is no definite evidence of systemic involvement.

A patient with adult-onset diabetes mellitus was referred with a diagnosis of malignant melanoma of the choroid of the left eye. A nonproliferative type of diabetic retinopathy was present, which was studied and documented by stereoscopic fundus photographs and fluorescein angiograms. Following enucleation, the microangiopathies were correlated histologically, using the retinal trypsin digest technique. Four types of microaneurysms were seen histologically that were believed to represent stages in the development of this lesion. Most thin-walled aneurysms tightly packed with erythrocytes did not fluoresce. Aneurysms that were hypercellular and those with thick walls showed early and late fluorescence. Intraretinal microvascular abnormalities were hypercellular dilated channels. Those that take origin from terminal arterioles are believed to represent attempts at neovascularization.

Occlusions of nine branch retinal veins in eight eyes of seven patients were studied histopathologically by serial sections through the affected areas. Intravitreal neovascularization from the disc, retina, or both was noted in four eyes. Two additional eyes had intraretinal neovascularization (intraretinal microvascular abnormalities). Cystoid macular edema was present in five eyes. A fresh or recanalized thrombus was noted at the site of vein occlusion in all eyes. Inner ischemic atrophy of the retina was found distal to the area of occlusion in six of the nine affected quadrants of the eight eyes. Although the corresponding branch retinal arteries showed varying degrees of sclerosis (severe, three eyes; moderate, five eyes; and minimal, one eye), no definite thrombus was observed in any of them.

We evaluated retrospectively the cases of 25 patients (26 eyes) with a recent, temporal, branch retinal vein obstruction to determine the relative anatomic position of the obstructed vein in relation to its crossing artery. In 26 (100%) of 26 eyes, the artery lay anterior to the vein, toward the vitreous cavity. A control group was obtained by evaluating the relative anatomic position between the branch retinal artery and vein at an equivalent crossing site along the opposite vascular arcade within the same eye. In the control crossing sites, the artery lay anterior to the vein 65% (15/23) of the time. We conclude that the likelihood that the artery will lie anterior to the obstructed vein at the site of blockage in a branch retinal vein obstruction is substantially greater than what would be expected by chance alone. This anatomic relationship between artery and vein probably plays a role in the cause of a branch retinal vein obstruction and may have therapeutic significance in light of a recent report concerning surgical treatment of such obstructions.

Vascular anastomoses between the retina and choroid may occur in different congenital and acquired conditions. It has been postulated that the direction of blood flow in these anastomoses follows a pressure gradient characterized as follows: choroidal artery greater than retinal artery greater than retinal vein greater than choroidal vein. Of the four possible directions of blood flow between the two circulations that this theory allows, only three have previously been reported. The fourth, described in this report, is a choroidoretinal vascular anastomosis with blood flow from a choroidal vessel into a retinal vein.

Vitreous fluorophotometry was used to measure blood-retinal barrier permeability to fluorescein in eight patients (mean age, 42.9 years; range, 30 to 55 years) with central retinal vein occlusion (CRVO). Permeability coefficient was derived by fitting a mathematical model to the posterior vitreous fluorescence scan and plasma-free fluorescein concentration curve at 60 minutes after intravenous fluorescein sodium (14 mg X kg-1). A permeability index (PI) was estimated by dividing the area under the vitreous fluorescence scan by the area under the plasma-free fluorescein curve. The permeability coefficient and PI were comparable and highly correlated. Initial mean permeability coefficient was 28.78 X 10(-7) cm X s-1 (range, 14.42 X 10(-7) to 41.10 X 10(-7) and 1.89 X 10(-7) cm X s-2 (range, 0.96 X 10(-7) to 2.76 X 10(-7) in eight affected and seven unaffected eyes, respectively. The permeability coefficient and PI in unaffected eyes did not differ significantly from 18 eyes of ten normal subjects. After three to 12 months, permeability coefficient and PI in affected eyes approached the values in the contralateral eyes of four patients with mild and one patient with moderate CRVO but remained elevated in the remaining patients. The permeability coefficient and PI correlated well with changes in severity of retinal appearances on color photographs and fluorescein angiograms. Vitreous fluorophotometry quantitated changes in blood-retinal barrier permeability in CRVO.