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Purpose: The current approach to the prevention of diabetic retinopathy relies on intensive anti-diabetes treatment and is only partially successful. A marker of retinopathy risk would enable strategies of surveillance, screening of adjunct drugs, and targeted drug interventions. The authors sought to identify early abnormalities of retinal vessels that are not prevented by the current therapeutic approach., Methods: Retinal thickness (an informer of vascular permeability) and hemodynamic parameters at baseline and longitudinally were measured in 27 subjects (age, 32 ± 9 years [mean ± SD]) with well-controlled type 1 diabetes of 12.4 ± 6.4 years' duration and no retinopathy, and in 27 control subjects. In a subset of 17 patients and 11 controls, the hemodynamic response to reclining, a postural change that increases retinal perfusion pressure, was measured., Results: Baseline foveal thickness and hemodynamic parameters were similar in the diabetic and control subjects. Foveal thickness increased over 12 months in the diabetic subjects, from 217 ± 22 μm to 222 ± 20 μm (P = 0.0036), remaining however within the normal range. Reclining uncovered in 47% of diabetic subjects (P = 0.016 compared with controls) an absent myogenic response (i.e., unchanged or increased arterial diameter instead of the normal decrease). The patterns were repeatable. Only the diabetic group with defective vasoconstriction showed widening arterial diameter over 12 months, a change presaging vascular dilatation in diabetic retinopathy., Conclusions: Defective myogenic response to pressure was the first detectable abnormality of retinal vessels in subjects with well-controlled type 1 diabetes. Because of its selective occurrence, interpretability in individual patients, and pathogenic potential, the abnormality deserves evaluation as a risk marker for retinopathy.

Purpose: To evaluate the relationship between retinal circulatory abnormalities and retinal nerve fiber layer (RNFL) thinning in early-stage open-angle glaucoma (OAG) to help elucidate the mechanisms underlying the development of glaucomatous optic neuropathy., Design: Prospective cross-sectional., Methods: Twelve patients with early OAG and a known maximum untreated intraocular pressure less than 22 mm Hg (age, 61.4 +/- 9.7 years; Humphrey visual field mean deviation -2.7 +/- 2.1) and eight age-matched healthy control subjects (age, 58.5 +/- 8.3 years) were included in the study. Blood column diameter, centerline blood speed, and retinal blood flow were measured in the major inferior temporal retinal artery using a Canon laser Doppler blood flow instrument (CLBF 100; Canon, Tokyo, Japan). Peripapillary RNFL thickness was measured using a Stratus optical coherence tomography instrument., Results: On average, there were significant reductions in retinal blood speed (P = .009) and flow (P = .010) in OAG patients compared to controls. The RNFL was significantly thinner in the OAG patients compared to controls (P = .002). There were significant inverse correlations between retinal blood flow and average RNFL thickness and RNFL thickness in the inferior quadrant within the glaucoma group (Rsq = 0.50, P = .01; Rsq = 0.62, P = .003)., Conclusion: The results showed that a thinner RNFL was associated with a higher retinal blood flow in patients with early-stage OAG. The mechanisms underlying this phenomenon remain to be elucidated.

Purpose: Waldenström's macroglobulinemia (WM) is characterized by an overproduction of immunoglobulin M (IgM), which can lead to a hyperviscosity syndrome (HVS) and HVS-related retinopathy. Plasmapheresis is known to reduce serum viscosity (SV) and IgM levels. The purpose of this study was to investigate the effects of plasmapheresis on HVS-related retinopathy and retinal hemodynamic parameters in patients with WM., Methods: Nine patients with HVS due to WM were studied. SV and plasma IgM levels were measured before and after plasmapheresis treatment. The patients were evaluated for HVS-related retinopathy, and hemodynamic changes in a major temporal retinal vein by laser Doppler, before and after plasmapheresis., Results: Plasmapheresis resulted in significant reductions in serum IgM (46.5% +/- 18.0%, mean +/- SD; P = 0.0009) and SV (44.7% +/- 17.3%, P = 0.002). HVS-related retinopathy improved in all patients after plasmapheresis. After treatment, the venous diameter decreased in each patient by an average of 15.3% +/- 5.8% (P = 0.0001). A significant (P = 0.0004) 55.2% +/- 22.5% increase in retinal venous blood speed accompanied the decreases in diameter. There was no significant change in the retinal blood flow rate after treatment. The percentage decreases in SV in the patients were significantly correlated with the percentage decreases in venous blood column diameter (P = 0.031, R(2) = 0.51)., Conclusions: HVS triggers a distinctive retinopathy with a central retinal vein occlusion (CRVO)-like appearance. However, the retinal blood flow is not decreased as in CRVO, but remains at normal levels. Plasmapheresis is effective in reversing HVS-related retinopathy and in reducing abnormal venous dilatation.

Aims/hypothesis: Abnormalities in retinal haemodynamics have been reported in patients with type 1 diabetes in advance of clinical retinopathy. These abnormalities could therefore be useful as early markers or surrogate endpoints for studying the microangiopathy. Since the DCCT, the increased focus on good glycaemic control is changing the natural history of diabetic retinopathy. Based on this, the aim of this study was to investigate whether patients with type 1 diabetes treated entirely or mostly in the post-DCCT era and tested in the absence of confounding factors show retinal haemodynamic abnormalities., Methods: We measured retinal haemodynamics by laser Doppler flowmetry in 33 type 1 diabetic individuals with no or minimal retinopathy (age 30+/-7 years, duration of diabetes 8.8+/-4.6 years, 9% showing microaneurysms), and 31 age- and sex-matched non-diabetic controls. The study participants were not taking vasoactive medications, and blood glucose at the time of haemodynamic measurements was required to be between 3.8 and 11.1 mmol/l., Results: HbA1c was 7.5+/-1.2% and blood glucose 7.7+/-2.8 mmol/l in these type 1 diabetic individuals, indicating relatively good glycaemic control. Retinal blood speed, arterial diameter and blood flow were not different between the diabetic individuals and the matched controls., Conclusions/interpretation: Type 1 diabetic patients with no or minimal retinopathy who maintain relatively good glycaemic control do not show abnormalities of the retinal circulation at steady state, even after several years of diabetes. In such patients it may be necessary to test the vascular response to challenges to uncover any subtle abnormalities of the retinal vessels.

Purpose: There is evidence suggesting that visual disturbances in patients with Alzheimer's Disease (AD) are due to pathologic changes in the retina and optic nerve, as well as to higher cortical impairment. The purpose of this study was to evaluate retinal hemodynamic parameters and to characterize patterns of retinal nerve fiber layer (RNFL) loss in patients with early AD., Methods: Nine patients with mild to moderate probable AD (mean Mini Mental State Examination score 24 of a possible 30 (age 74.3 +/- 3.3 years; mean +/- SD) and eight age-matched control subjects (age, 74.3 +/- 5.8 years) were included in this prospective cross-sectional study. Blood column diameter, blood velocity, and blood flow rate were measured in the major superior temporal retinal vein in each subject by using a laser Doppler instrument. Peripapillary RNFL was measured by optical coherence tomography., Results: Patients with AD showed a significant narrowing of the venous blood column diameter (131.7 +/- 10.8 microm) compared with control subjects (148.3 +/- 12.7 microm, P = 0.01), and a significantly reduced venous blood flow rate (9.7 +/- 3.1 microL/min) compared with the control subjects (15.9 +/- 3.7 microL/min, P = 0.002). A significant thinning of the RNFL was found in the superior quadrant in patients with AD (92.2 +/- 21.6 microm) compared with control subjects (113.6 +/- 10.7 microm, P = 0.02). There were no significant differences in the inferior, temporal, or nasal RNFL thicknesses between the groups., Conclusions: Retinal abnormalities in early AD include a specific pattern of RNFL loss, narrow veins, and decreased retinal blood flow in these veins. The results show that AD produces quantifiable abnormalities in the retina.

Objectives: To determine the earliest retinal changes associated with Waldenström macroglobulinemia (WM) and to ascertain the serum IgM and serum viscosity (SV) levels at which these changes occur., Methods: Patients with WM were evaluated using indirect ophthalmoscopy with scleral depression, laser Doppler retinal blood flow measurements, and serum IgM and SV determinations. Hemodynamic findings were compared with those of a group of age-matched controls. A retinopathy severity scale was developed, and the associated IgM and SV values were related to particular morphologic changes., Results: A total of 46 patients with WM and 14 age-matched, healthy controls participated in the study. Patients exhibited far-peripheral hemorrhages and venous dilation with increasing SV and IgM values. Central retinal changes were associated with significantly higher SV values. Retinal vessel diameter increased with increasing serum IgM and SV levels. The mean IgM level of patients with the earliest retinal changes was 5442 mg/dL. The mean SV level was 3.1 cP., Conclusions: Retinal manifestations of hyperviscosity syndrome occur at lower serum IgM and SV levels than previously reported. Indirect ophthalmoscopy with scleral depression along with retinal vessel diameter measurements are able to detect the earliest hyperviscosity syndrome-related complications and should be considered in the treatment of patients with WM.

Background: A number of epidemiological studies suggest that age-related macular degeneration (AMD) and cardiovascular disease share the same risk factors. Systemic arterial stiffness is a clear indicator of cardiovascular disease. We investigated whether there is an association between directly measured systemic arterial stiffness and the presence of AMD., Methods: We used a SphygmoCor 2000 system to noninvasively measure two indicators of the systemic arterial stiffness, the arterial pulse wave velocity (PWV) and the central aortic blood pressure waveform, from which the augmentation pressure is determined. We studied 50 patients with AMD (12 men, 38 women, aged 60 to 91 years, mean 77 years) and 11 age-matched control subjects (3 men, 8 women, aged 66 to 92 years, mean 75 years). All study subjects received a complete ophthalmic examination including digital fundus photography. All of the patients with AMD were classified as stage 3 or worse in at least one eye according to the AREDS system., Results: Pulse wave velocity was significantly higher in the patients with AMD (8.2+/-1.1 m/s, mean +/- SD) compared with controls (7.1+/-0.8 m/s, p=0.0025), indicating increased arterial stiffness. There was no significant difference in PWV in AMD patients with and without choroidal neovascularization. There was no association between PWV and the presence of hypertension in either the patients or the controls. The central aortic augmentation pressure was significantly higher in the AMD patients than in the controls (p=0.040), also indicating increased arterial stiffness., Conclusions: Patients with AMD have increased systemic arterial stiffness compared with age-matched controls. Treatments aimed at preventing or reversing systemic arterial stiffness may also be effective in preventing the onset or slowing the progression of AMD.

Purpose: To describe a newly developed stabilized retinal laser Doppler instrument, to report the reproducibility of retinal blood flow measurements, and to present examples of its clinical application., Design: Experimental study., Methods: The intrasession, intersession, and interobserver reproducibility of retinal blood flow measurements obtained using the Canon Laser Blood Flowmeter model CLBF 100 was assessed. Intrasession: the coefficients of variation (CV) for repeated measurements (5X) of retinal vessel diameter (D), time-average centerline blood velocity (V(av)), and blood flow (F) were calculated at 18 sites along temporal retinal arteries and 18 sites along temporal retinal veins using both eyes in six healthy volunteers. Intersession: the correlation coefficients and average differences between two sets of measurements at the same 36 retinal sites made by one examiner on two different days were calculated. Interobserver: the correlation coefficients and average differences between two sets of measurements at nine sites (five arterial and four venous) in five eyes of five of the volunteers made by two examiners on the same day were calculated. Results from two patients, one with branch retinal vein occlusion (BRVO), and one with central retinal vein occlusion (CRVO), are used to illustrate abnormal retinal circulatory characteristics., Results: intrasession: CV (mean +/- SD) for D, V(av), and F were 5.5% +/- 2.2%, 13.1% +/- 6.3%, and 13.8% +/- 4.7% in arteries and 3.5% +/- 2.1%, 11.9% +/- 5.9%, and 12.7% +/- 5.5% in veins. Intersession/interobserver: strong correlations between measurements made by one examiner on two different days and by two examiners on the same day were found in D, V(av), and F. Average differences in F were 16.4% +/- 12.8% for intersession and 12.6% +/- 7.0% for interobserver comparisons. Results from the patient with BRVO show marked differences in flow characteristics in the affected quadrant compared with an unaffected quadrant in the same eye, and to the fellow eye. Results from the patient with CRVO show a dramatic improvement in flow characteristics after clearing of the occlusion., Conclusions: The reproducibility results and the fact that blood flow is measured in actual units of microl/min indicate that the instrument can be used for reliable comparison of blood flow characteristics at different retinal vascular sites in the same eye, at comparable sites in both eyes, and for comparison between patients and healthy control subjects., (Copyright 2003 by Elsevier Science Inc.)

Objective: To describe the clinical presentation and management of erosion and intrusion of silicone rubber implants that are used in scleral buckling procedures for the treatment of retinal detachment., Methods: The authors identified four patients from their practices during the last 20 years (1978-1998) who had erosion or intrusion of silicone rubber scleral buckles that were used to manage retinal detachment. Approximately 4400 scleral buckling procedures were performed during this period. A retrospective review of the medical records of all patients was performed. Factors that influenced management decisions concerning the intruding buckle are emphasized., Results: All four patients had myopia. The interval between placement of the scleral buckle and development of intrusion ranged from 1 to 20 years. The buckles were intrascleral in three cases and episcleral in one. Recurrent detachment and vitreous hemorrhage were indications for surgical intervention in three cases. After the surgical removal of buckling elements, visual acuity stabilized in all patients and the retina remained attached in all cases., Conclusions: Erosion and intrusion of scleral buckle are rare complications of scleral buckling procedures. The intruding buckle may be left intact unless there is significant threat to the integrity of ocular structures, recurrent detachment, or hemorrhage. Manipulation of the encircling band or buckle does not necessarily alter the visual acuity or the status of the retina.

Although the roles of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) in angiogenesis are well described, the putative roles of these factors in retinopathy of prematurity (ROP) remain unknown. We evaluated VEGF and HGF protein levels in subretinal fluid of eyes with ROP, and expression of their corresponding receptors in retrolental membranes associated with stage 5 ROP. We examined subretinal fluid samples from eyes using rhegmatogenous retinal detachment as a control. VEGF and HGF were differentially elevated in eyes with ROP. In Stage 5 ROP (n = 22), the mean VEGF and HGF levels were 14.77 +/- 14.01 ng/ml and 16.56 +/- 9.62 ng/ml, respectively. Interestingly, in patients with active stage 4 ROP, mean VEGF levels were highly elevated (44.16 +/- 18.72 ng/ml), whereas mean HGF levels remained very low (4.77 +/- 2.50 ng/ml). Next, we investigated in vivo expression of VEGF receptor-2 and HGF receptor in retrolental membranes from 16 patients with stage 5 ROP. Both VEGF receptor-2 and HGF receptor proteins were detected mainly in posterior portions of the membrane as well as in vessel walls and along the retinal interface where angiogenesis was active. These findings together suggest that VEGF and HGF play important roles in the pathogenesis of ROP.

Purpose: To investigate the systemic and ocular factors associated with diffuse macular edema in patients with diabetic retinopathy (DR) and compare with patients with focal or no macular edema., Methods: From 160 consecutive patients with DR, we obtained medical and ocular histories, blood pressure and visual acuity. Macular edema was determined by biomicroscopy and stereoscopic fundus photography. Fluorescein angiography was used in the characterization of its leakage, and the vitreoretinal relationship was performed by preset lens biomicroscopy., Results: Among adult-onset diabetes mellitus (DM) patients, 55% had diffuse, 23.5% had focal and 21.5% had no macular edema (p=0.01). The risk of developing diffuse macular edema was 3.2 times greater in patients with high blood pressure (HBP) (95% confidence interval (CI), 1.5 to 6.9). Patients with cardiovascular disease (CVD) had a higher prevalence of diffuse (58.0%) than focal (26.0%) or no maculopathy (16.0%) (p=0.01). The odds for development of diffuse macular edema was 3.4 times greater in patients with vitreomacular adhesion (95% CI, 1.15 to 13.30) than in those with complete posterior vitreoretinal attachment or vitreoretinal separation. The odds for development of diffuse macular edema were 6.2 (95% CI, 1.83 to 21.04) and 7.7 times greater (95% CI, 3.12 to 19.12) in patients with PPDR and PDR, respectively, in comparison with those with NPDR., Conclusions: In this study, adult-onset DM, HBP, CVD, vitreomacular adhesion and advanced retinopathy were associated with increased risk of development of diffuse diabetic macular edema.

A new laser Doppler system for the noninvasive examination of the human optic nerve head microcirculation is described. The electro-optical component of the system consists of a retinal camera modified with laser input optics and a fiber optic light detection system for collection of the Doppler-shifted scattered light. Data acquisition is carried out in real time under computer control. Automated analysis of the data provides a quantitative measure of the speed of blood cells flowing through the capillaries of the optic nerve head. Unlike previous systems, this system provides results within a few minutes following data acquisition. It is thus appropriate for use in a clinical setting. Analysis of multiple measurements on a patient shows a coefficient of variation of 8.9%. © 1998 Society of Photo-Optical Instrumentation Engineers.

We developed a new laser Doppler instrument to measure retinal blood flow. This instrument is equipped with an eye tracking system, which maintains the laser beam on the retinal vessel, thus enabling the measurement of patients with poor visual acuity and poor fixation. In diabetic patients even those without retinopathy, the retinal blood flow decreased compared to the control subjects. This was mainly the result of decreased retinal blood speed and no significant change in the arterial diameter. In diabetic patients requiring panretinal photocoagulation, we studied the regional changes in retinal blood flow following superior or inferior half fundus argon laser treatment, which produced a significant retinal blood flow decrease only in the treated area. We also studied the retinal circulatory changes in retinal branch vessel occlusion. In retinal branch view occlusion, the blood flow in arteries supplying the affected lesion showed 80-90% decrease compared to the arteries supplying the unaffected region. In retinal branch artery occlusion, the retinal blood flow in occluded arteries showed 40-50% decrease compared to the non-occluded arteries. In one patient with retinal branch vein occlusion in whom we measured the retinal blood flow over 18 months, the blood flow increased with the development of collateral vessels. The results showed that retinal circulatory abnormalities can be also evaluated quantitatively during the course of retinal vascular occlusive disease by our newly developed laser Doppler instrument, which proved that this instrument is a clinically very useful tool.

In a double-masked, randomized, placebo-controlled, two-period crossover study, we measured the effect of aspirin on retinal blood flow in 8 type I diabetic patients, 5 with no observable retinopathy, and 3 with 1-10 observable microaneurysms and no other signs of retinopathy. Each patient ingested 1 capsule/day of either aspirin (650 mg) or placebo for 14 days. Following a 1-month washout period, the treatment was reversed. The bidirectional laser Doppler technique and monochromatic photography were used to measure the blood flow rate in a major temporal retinal artery in 1 eye of each patient at baseline and on the 14th day of each treatment period. Retinal blood flow increased following aspirin in 7 of the 8 patients. Using a standard crossover analysis we found a mean aspirin-placebo treatment difference of 21 +/- 17% (mean +/- 95% CI), which was statistically significant (p = 0.03). Retinal blood flow increased following aspirin by 44 +/- 10% (mean +/- SEM) in the 5 patients with no retinopathy (p = 0.04), but only by 8 +/- 10% (n.s.) in the 3 patients with minimal retinopathy.

The laser Doppler technique and monochromatic photography were used to measure the total retinal blood flow, temporal/nasal differences in blood flow and the relationship between blood flow and vessel diameter in 5 healthy subjects, aged 54-58 years. Systemic blood pressure (BP) and intraocular pressure were also measured, and the retinal perfusion pressure was calculated. The measurements were compared to those previously obtained from a younger group of 7 healthy subjects, aged 25-38 years. Total retinal blood flow was 73 +/- 13 microliters/min in the middle-aged subjects and was not significantly different from the value measured in young subjects (80 +/- 12 microliters/min). Retinal perfusion pressure was significantly higher in the older subjects, primarily due to elevated systemic BP. The similarity in total flow between the two groups, even though the retinal perfusion pressures were higher in the older group, is an indication of an increased vascular resistance to flow. The increase may be an aging phenomenon or an indication of a well-functioning autoregulatory capacity in the retinal vasculature of the older subjects.

We retrospectively reviewed the eyes of 143 patients with tractional retinal detachment caused by diabetes that had been studied biomicroscopically, and, after some exclusions, divided them into two groups: those with retinal breaks (group 1) (16 patients, 16 eyes), and those without retinal breaks (group 2) (127 patients, 161 eyes). The group 1 eyes were further divided into three subgroups: those with retinal tears from limited anteroposterior vitreous traction (subgroup A), those with macular holes in an area without posterior vitreous detachment (subgroup B), and those with oval retinal holes anterior to the anteroposterior vitreous traction (subgroup C). Subgroup C comprised most of the eyes in group 1 (10 eyes) and was the only subgroup that we compared with group 2. Significant differences between subgroup C and group 2 were found in terms of the extent of tractional retinal detachment (P = .002) and the degree of preretinal fibrosis (P = .009). These data suggest that large tractional retinal detachments and extensive preretinal fibrosis are significant risk factors for the development of retinal breaks in proliferative diabetic retinopathy.

Regional changes in retinal blood flow following inferior and subsequent superior argon laser half fundus photocoagulation treatment were measured in six diabetic patients with advanced retinopathy. Centreline blood velocity, vessel diameter, and blood flow in major inferior and superior temporal retinal arteries were measured at baseline and following each treatment using the bidirectional laser Doppler technique and monochromatic fundus photography. Inferior fundus laser treatment produced a significant blood flow decrease in inferior temporal arteries ranging from 60% to 78%. Blood flow changes in superior temporal arteries were not significant, ranging from -7% to +14%. Subsequent superior fundus laser treatment produced a significant blood flow decrease in superior temporal arteries ranging from 50% to 66%. Subsequent blood flow changes in inferior temporal arteries were not significant, ranging from -19% to +21%. The results indicate that regional laser treatment produces a regional reduction in retinal blood flow, consistent with measurements of preretinal and intraretinal oxygen tension which have indicated increases in oxygen over photocoagulated regions.

We retrospectively studied the correlation between the initial electroretinogram (ERG) recordings and the final visual acuities (VA) of 47 patients with central retinal vein obstruction (CRVO) after follow-up of more than 1 year. The a- and b-wave amplitudes and the b/a ratio with white flash were significantly larger in patients with good vision (VA > 20/200) than in those with poor vision (VA < or = 20/200). The b/a ratio and b-wave amplitude with white flash showed sensitivity and specificity of more than 78% for visual prognosis. The latest VA was < or = 20/200 in all 20 patients with a subnormal b-wave amplitude and in all 15 with b/a ratio < 1.05. These results suggest that the ERG recorded soon after (CRVO) onset correlates strongly with visual prognosis.

We used the laser Doppler technique to quantify retinal circulatory abnormalities in three patients with branch retinal artery occlusion and in two patients with branch retinal vein occlusion, each of whom had shown delayed filling on fluorescein angiography. Blood flow in occluded arteries was 40-50% lower than in non-occluded arteries of the same branching order. In the patients with branch retinal vein occlusion blood flow in arteries supplying the affected regions was 80-90% lower than in arteries supplying the unaffected regions. One vein occlusion patient was measured serially over 18 months. Blood flow increased from 4 to 12 microliters/min in the artery supplying the affected region in this patient. The results demonstrate that retinal circulatory abnormalities can be evaluated quantitatively during the course of retinal vascular occlusive disease, and suggest that the efficacy of therapy can be monitored using our techniques.

We used magnetic resonance spectroscopy to examine endophthalmitis in rabbits inoculated with a virulent strain of Streptococcus pneumoniae. On different days after infection, the animals were sacrificed and the vitreous isolated and examined with water-suppressed proton magnetic resonance spectroscopy. A broad resonance corresponding to the methyl envelope of lipoprotein lipids appeared 2 days after infection and persisted until the eyes developed phthisis (around 10 days postinfection). This resonance was absent in the control eye and the bacterial culture; it could be used as the marker of breakdown of blood-vitreous barrier and onset of endophthalmitis-induced changes.

The efficacy of proton magnetic resonance imaging (MRI) was evaluated and compared with that of B-scan ultrasound in the detection and differentiation of diabetic vitreous hemorrhage. Although conventional spin-echo MRI could not locate vitreous hemorrhages, gradient-recalled-echo (GRE) MRI readily did so. The aberrant signals appeared to originate from the interfacing between hemorrhages and the vitreous, and possibly also from the paramagnetic effect of the ferrous ion. The information provided by boundary/susceptibility detection, unique to the GRE sequence, is useful in delineating the extent of vitreous hemorrhage and hemolysis. However, for the diagnosis and follow up of diabetic vitreous hemorrhages, MRI appears no more informative than B-scan ultrasonography.

The bidirectional laser Doppler technique and monochromatic photography were used to measure the absolute blood flow rate in the major temporal retinal arteries in seven patients following unilateral scleral buckling and encircling procedures, and in two patients before and after removal of scleral buckling elements. In the seven patients who had undergone uncomplicated scleral buckling procedures the arterial flow rates were on average 50% lower (p = 0.01) in the surgically treated eyes than in the contralateral eyes. Removal of scleral buckling elements in two patients produced increases of 73% and 44% in arterial blood flow rates.

The authors studied the characteristics of 376 eyes of 361 patients with primary retinal detachment (RD) and surgical aphakia (103 eyes) or pseudophakia (273 eyes). Of the pseudophakic eyes, 17 had an iris-fixated intraocular lens (IOL), 111 had an anterior chamber (AC) IOL, and 145 had a posterior chamber (PC) IOL. Of the PC IOL cases, 48 (33%) had undergone YAG capsulotomy, and 46% of them developed RD within 6 months after capsulotomy. The frequency of no breaks found in pseudophakic RD (15%) was significantly higher than in RD with simple aphakia (5%). The most frequent reasons were incomplete fundus view due to a small pupil in the iris-fixated (83%) and the AC (44%) groups, and cloudiness of capsular remnants in the PC group (78%). In pseudophakic RD, sizable single tears, located more posteriorly than in RD with simple aphakia, were frequent. The authors speculate that in pseudophakic RD the retinal breaks may resemble those noted in phakic RD.

The authors studied the results obtained by the Retina Associates in 376 eyes of 361 patients operated on for retinal detachment associated with aphakia or pseudophakia with a postoperative follow-up of at least 6 months. All eyes underwent scleral buckling. The series included 103 eyes with aphakia, 17 eyes with iris-fixated intraocular lens, 111 eyes with anterior chamber (AC) IOL, and 145 eyes with posterior chamber (PC) IOL. The overall success rate for retinal detachment was 93%, without significant difference among the different groups. The aphakia and PC IOL groups had significantly higher prevalence (63% and 60%, respectively) of visual acuity equal to or better than 20/40 compared with the AC IOL group (33%). The prevalence of postoperative corneal edema in the AC IOL group was significantly higher than in the aphakia and PC IOL groups. Preoperative vitreous hemorrhage, large retinal breaks, posterior retinal breaks, total retinal detachment, proliferative vitreoretinopathy, and the need for performing a closed vitrectomy were significant factors in predicting ultimate failure.

Bidirectional laser Doppler technique and monochromatic photography was used to measure the absolute blood flow rate (F) in the major superior or inferior temporal retinal arteries in 3 patients with rhegmatogenous retinal detachment, in 4 patients following unilateral scleral buckling procedures, and in one patient before and after removal of scleral buckling elements. In 2 of the eyes with retinal detachment, F in arteries supplying the detached portion of the retina was approximately 30% lower than in arteries supplying the attached portion. On average, F measured in the arteries supplying the detached portion of the retina in 2 patients was 8.9 +/- 1.3 microliters/min, 67% lower than normal controls. F measured in the arteries supplying the attached portion of the retina in 3 patients was 15.2 +/- 3.9 microliters/min, on average, 43% lower than in normal controls. In 4 patients who had undergone uncomplicated, unilateral scleral buckling procedures, F in an artery of the affected eye was compared with F in the corresponding artery of the fellow eye. F in the artery of the affected eyes was 8.7 +/- 3.2 microliters/min, on average, 59% lower than that of the fellow eyes (p less than 0.05), and 68% lower than in normal controls (p less than 0.0001). Removal of scleral buckling elements in one patient produced a 79% increase in F in the measured artery. Then, F returned to normal levels after removal of scleral buckling elements.

Magnetic resonance (MR) micro-imaging was performed on enucleated eyes from rabbits previously injected with perfluoropropane gas (C3F8), with or without the surgical creation of retinal detachment. Condensed vitreous, which exhibited shortened longitudinal relaxation time (T1), could be differentiated with proton-density and T1-weighted imaging. Gradient-echo imaging could in addition detect vitreo-retinal tractions. The detached retina itself was also seen. Further, proton-density but not T1-weighted imaging showed lens opacities appearing as high-intensity regions. MR microscopy is a convenient method for gross morphological examination of intact eyes.

The efficacy of proton magnetic resonance imaging in differentiating vitreous from C3F8 gas and silicone oil tamponades, and in detecting fresh hemorrhages and condensed vitreous was tested in rabbits in vivo. The results suggest that this imaging method could provide a useful alternative to ultrasonography, especially in eyes with opaque media.

In a double-masked, randomized, placebo-controlled study, we evaluated the effect of topical timolol maleate 0.5% on the retinal, choroidal, and optic nerve head circulation in 5 healthy volunteer subjects. Changes in the pulsatile component of choroidal blood flow (PCBF) were determined from measurements of the ocular pulse wave. Changes in the retinal arterial blood flow rate (RBF) and optic nerve head capillary blood speed (CBS) were determined by laser Doppler velocimetry and monochromatic photography. In timolol-treated eyes, PCBF decreased by 32 +/- 12% (p = 0.0007). Changes in RBF and CBS were not statistically significant. In the contralateral placebo-treated eyes, PCBF decreased by 15 +/- 8% (p = 0.006) and RBF increased by 18 +/- 10% (p = 0.002). The change in CBS was not statistically significant.

We prospectively studied 29 consecutive eyes with proliferative diabetic retinopathy that showed media clear enough to enable characterization of vitreoretinal relationships by biomicroscopy. Vitreoretinal relationships were also determined by contact B-scan ultrasound. With both techniques, these relationships were documented by photographs and drawings. Biomicroscopy showed complete posterior vitreous detachment (PVD) in 4 eyes (14%), partial PVD in 18 (62%), and no PVD in 7 (24%). Ultrasound examination revealed complete PVD in 4 eyes (14%), partial PVD in 19 (66%), and no PVD in 6 (21%). The results we obtained using ultrasound agreed significantly with those obtained by biomicroscopy [Cohen's kappa = 0.93, 95% confidence interval = (0.80, 1.06)]. Ultrasound detected vitreous changes more easily than biomicroscopy when mild media opacities were present and when the equatorial areas of the globe were examined. Results suggest that ultrasound is adequate to determine vitreoretinal relationships in eyes with clear media and that it is a good alternative to biomicroscopy in eyes with significant media opacities.

A total of 30 eyes of 19 patients with type I diabetes, varying severity of retinopathy, and no posterior vitreous detachment (PVD) were studied clinically, and vitreous examination was performed by preset lens biomicroscopy. Follow-up was 4.0-7.5 years. A total of 15 eyes underwent panretinal laser photocoagulation (PRP) and 15 eyes were left untreated. The incidence of PVD was 8 of 15 353%) after PRP and 1 of 15 (7%) in untreated eyes (P less than 0.02). Minimal vitreous hemorrhage occurred in 4 of 7 treated eyes (57%) that did not develop PVD and in only 2 of 8 (25%) that did. In treated eyes with no history of vitreous hemorrhage, the incidence of PVD was 6/9 (67%); in treated eyes with minimal vitreous hemorrhage at any time, it was 2/6 (33%). In treated eyes, the presence of Diabetic Retinopathy Study (DRS) high-risk characteristics was equally frequent in eyes that developed PVD as in those that did not. These data suggest that PVD occurs following PRP, independent of the severity of diabetic retinopathy or prior vitreous hemorrhage.

In eight eyes of eight patients we retrospectively studied the outcome of subretinal hemorrhage occurring in areas of atrophy of retinal pigment epithelium and choriocapillaris secondary to age-related macular degeneration. These patients were followed up for one to 20 months after the initial appearance of the hemorrhage. No subretinal new vessels were associated with these hemorrhages, which resolved over one to 15 months. Our findings indicated that hemorrhages occurring within areas of atrophy are not necessarily associated with subretinal new vessels, and that this type of hemorrhage has a good prognosis for resolution.

Retinal mean circulation time (MCT) and vascular sizes were measured in 21 normal individuals and 32 individuals with diabetes, and segmental blood flow (SBF) was calculated. The MCT was similar in the normal individuals (4.0 +/- 1.1 s) and the individuals with diabetes (4.2 +/- 1.9 s) when seven individuals with diabetes with prolonged but not quantifiable MCT were excluded. Including them by nonparametric statistics revealed that MCT was significantly longer in individuals with diabetes with proliferative retinopathy than in normal individuals or in individuals with diabetes with nonproliferative retinopathy. The prolonged MCT correlated significantly with advanced retinopathy as judged by leakage, neovascularization, and the need for photocoagulation therapy. Reduced SBF may account for the prolonged MCT, since the increase in vascular sizes observed failed to do so. However, pathologic vascular changes may alter the relation between SBF and MCT. Irrespective of implications about SBF, prolonged MCT, which indicates marked circulatory disturbance, represents an important new observation in diabetic retinopathy.

We examined the vitreous in 163 eyes with diabetic retinopathy using a +58.6-diopter aspherical preset lens and a slitlamp. Sixty-eight eyes had no vitreous detachment, 76 eyes had partial vitreous detachment, and 19 eyes had complete vitreous detachment. This article studies the vitreoretinal relationship to determine its role in the progression of proliferative diabetic retinopathy. We found that partial vitreous detachment with vitreoretinal traction is a major risk factor for progression of proliferative diabetic retinopathy, whether or not photocoagulation is performed. With complete vitreous detachment or with no vitreous detachment, the absence of vitreous traction protects against the progression of proliferative diabetic retinopathy.

Data from 5,818 eyes with diabetic retinopathy were entered into a computer. Retrieval was either panoramic, encompassing the whole bank, or directed to small groups for in-depth investigation. In this study, panoramic retrieval pertains to the relative frequency of nonproliferative and proliferative diabetic retinopathy, to insulin dependence, and to the visual prognosis associated with these variables. Small-group studies examined traction detachment and vitreous hemorrhage in relation to visual prognosis and postmortem data related to age at death and "final vision".

The newly developed laser Doppler technique was used to measure retinal blood flow characteristics in patients with forms of central retinal venous occlusive disease. The measurements were consistent with the expected reduced retinal blood flow in these disease processes.

To quantify the vascular deterioration of the diabetic retina, retinal circulatory changes in 45 insulin-dependent diabetic patients, and in 17 normal controls, were measured and divided into four groups according to severity of retinopathy. The noninvasive laser Doppler technique was used to measure the systolic/diastolic variation of red blood cell velocity (V) at sites along temporal retinal arteries. Flow pulsatility [V (systole)/V (diastole)] was 18% lower (P less than 0.00001) in the mild-retinopathy group than in normal controls, but 35% higher (P less than 0.001) in the severe-retinopathy group than in the mild-retinopathy group. Repeated measurements in three eyes during the progression from mild or moderate to severe retinopathy showed progressive increases in both flow pulsatility and mean retinal blood flow. Altered flow pulsatility appears to be a sensitive indicator of vascular alterations during the progression of diabetic retinopathy.

Prior to the era of vitrectomy, scleral buckling was used to treat 521 eyes with total retinal detachment and proliferative vitreoretinopathy (PVR) of various degrees of severity. The retina was reattached for at least six months in 46.9% of eyes; the anatomic success rate decreased with increasing severity of PVR. Within each grade of PVR, the reattachment rate was higher for eyes with smaller breaks than for eyes with larger breaks, and the prognosis was not worse when smaller breaks were found than when no breaks were found. The cumulative success rate rose with increasing number of reoperations. None of the anatomically successful cases had a final visual acuity of no light perception; 82.9% of them achieved a visual acuity of counting fingers or better. The prognosis for visual improvement after successful scleral buckling was unrelated to the preoperative severity of PVR. Severe intraoperative complications occurred in 5.0% of the eyes, all of which resulted in failure.

Seventy-five cases of total retinal detachment complicated by the more advanced grades (grades C and D) of proliferative vitreoretinopathy were treated with scleral buckling, vitrectomy, and air-fluid exchange. The overall reattachment rate was 56%, ranging from 100% in grade C-1 to 26% in grade D-3. The postoperative visual acuity was 6/120 or better in 48% of the 42 eyes in which the retina was reattached. The major causes of surgical failure were redetachment from persistent vitreoretinal traction (32%) and intraoperative complications (12%).

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.

A 14-year-old Iranian girl was referred for evaluation of bilateral elevation of the peripapillary retina. Fluorescein angiography was consistent with bilateral peripapillary exophytic retinal hemangioblastomas as seen in angiomatosis retinae (von Hippel's disease). Argon laser photocoagulation of the more severely affected left eye was performed with minimal effect upon the tumor.

The authors assessed retrospectively clinical records of 76 patients (125 eyes) 60 years of age or older with diabetic retinopathy who had undergone a vitreous examination. The groups consisted of 105 eyes (63 patients) with macular edema and 20 eyes (13 patients) without macular edema. Vitreous studies were done using the El Bayadi-Kajiura lens to determine whether or not the posterior vitreous was attached to the retina in the macula. Twenty-one of 105 eyes (20.0%) in the edema group and 11 of 20 eyes (55.0%) in the no-edema group had a detached posterior vitreous. This difference was found to be statistically significant, indicating that diabetic cases without macular edema have a significantly higher rate of posterior vitreous detachment than those with macular edema. This study demonstrates that the vitreous may play a role in diabetic macular edema.

Relative merits of different laser wavelengths for macular photocoagulation are analyzed in terms of light scattering and light absorption in hemoglobin, melanin, and macular xanthophyll. Disadvantages of inner retinal damage in the macula caused by the blue-green argon photocoagulators in standard clinical use are discussed, along with advantages of argon green and krypton yellow light. Results of treatment of subretinal neovascularization in disciform macular degeneration are presented. A repetitive treatment, close follow-up protocol was employed with the objectives of closing neovasculature and preserving central visual field. In 74 successive patients treated with monochromatic argon green radiation, neovasculature was closed in 93%, central visual field loss was reduced or stabilized in 76%, and visual acuity was improved or stabilized in 70%. Results were analyzed in terms of location and size of the neovascular membrane, and it was found that best results were obtained with neovascularization farther than 600 microns from the foveola and smaller than 2 mm2. In 17 patients with neovascular membranes more than 600 microns from the foveola, neovasculature was closed in 100%, central visual field loss was reduced or stabilized in 94%, and visual acuity was improved or stabilized in 88%. Similar results were obtained with monochromatic krypton yellow radiation.