Thomas C. Burton

Risk factors for hemiretinal vein occlusion : Comparison with risk factors for central and branch retinal vein occlusion the eye disease case-control study

OBJECTIVE Possible risk factors for hemiretinal vein occlusion were identified and compared with risk factor profiles for central and branch retinal vein occlusion. DESIGN The design was a multicenter case-control study. METHODS The authors identified 79 patients with hemiretinal vein occlusion (HRVO), 258 patients with central retinal vein occlusion (CRVO), 270 patients with branch retinal vein occlusion (BRVO), and 1142 control subjects at 5 clinical centers. Risk factor data were obtained through interviews, clinical examinations, and laboratory analyses of blood specimens. RESULTS Systemic hypertension and history of diabetes mellitus were associated with increased risk of HRVO. Risk of CRVO increased with history of diabetes, systemic hypertension, and higher erythrocyte sedimentation rate (females only); risk of CRVO decreased with increasing amounts of physical activity and increasing amounts of alcohol consumption. Systemic hypertension, higher body mass index, and higher alpha2-globulin levels were associated with increased risk of BRVO, whereas higher high-density lipoprotein levels and increasing levels of alcohol consumption were associated with decreased risk of BRVO. Glaucoma history was associated with all three types of retinal vein occlusion. CONCLUSION Patients presenting with retinal vein occlusion should be evaluated for cardiovascular disease, diabetes, and glaucoma.

Arteriovenous Crossing Patterns in Branch Retinal Vein Occlusion

PURPOSE The study was designed to evaluate the relative anatomic position of the crossing vessels at the site of occlusion in eyes with branch retinal vein occlusion (BRVO). METHODS Fundus photographs of 106 eyes (104 patients) with recent BRVO from the Eye Disease Case-Control Study were used to examine the relative position of artery and vein at occluded crossings. Three separate comparison groups were formed by identifying corresponding arteriovenous crossings for each occluded crossing in: (1) the ipsilateral but opposite vessel arcade within eyes affected by BRVO; (2) the same quadrant in unaffected eyes of BRVO patients; and (3) the same quadrant in eyes of patients without BRVO, matched by age, sex, and race with the BRVO patients. RESULTS The site of obstruction of the branch vein was an arteriovenous crossing in all affected eyes. In 99% of eyes with BRVO, the artery was located anterior to the vein at the obstructed site. In the three comparison groups, the artery was anterior to the vein in 62%, 61%, and 54% of the crossings, respectively, yielding statistically significant differences for each group of control crossings compared with BRVO crossings (P < 0.001). CONCLUSION Finding the vein to be consistently between the more rigid artery and the retina at almost all arteriovenous crossings affected by BRVO suggests a possible role for mechanical obstruction in the pathogenesis of BRVO.

The incidence of macular pucker after retinal detachment surgery.

In a study of 63 cases of macular pucker among 857 patients who underwent retinal detachment repair, we isolated several statistically significant risk factors: preoperative vision of less than 6/15 (20/50); preoperative presence of rolled edges, starfolds, or equatorial ridges; re-operations; choroidal hemorrhage; and age past 30 years. We were unable to confirm the risk associated with vitreous loss, vitreous hemorrhage, and degeneration. Results suggested that macular pucker after detachment surgery is produced by a membrane similar in origin to those causing other forms of periretinal proliferation.

CENTRAL RETINAL VEIN OCCLUSION IN YOUNG ADULTS (PAPILLOPHLEBITIS)

We performed a retrospective study of 103 cases of central retinal vein occlusion (CRVO) in young, nondiabetic adults that were followed for at least six months. Of these patients, 64% were men and 36% were women. While visual acuity was usually good, 33 eyes (32%) had a final visual acuity of 20/200 or worse, including 6 eyes (6%) with a final visual acuity of no light perception. Ocular complications included chronic cystoid macular edema, macular pigmentary changes (37%), sheathing of retinal vessels (22%), venous collaterals of the disc (33%), macular hole formation (1%), neovascularization of the disc (1%), retina (1%), and iris (19%), neovascular glaucoma (8%), and vitreous hemorrhage (7%).

A Predictive Model for Visual Recovery Following Retinal Detachment Surgery

By multiple regression analysis we have identified 26 out of 200 observations which significantly affect the visual acuity following retinal detachment surgery. In addition, we have developed a highly significant mathematical model, which is able to predict in rather broad ranges of visual acuity to approximately 67% accuracy. There is still a large percentage of patients for whom we cannot account for the variability in final vision, a problem requiring future investigation. Potentially important factors which were not analyzed in this study include duration of macular detachment, afferent pupil defect, drainage of subretinal fluid, extent of the scleral-buckling procedure, and postoperative follow-up longer than six months. While most of the variables are fixed and cannot be alterd, such as age, senile cataract, and refractive error, improved knowledge of influential factors may allow us to manipulate some of them and provide mechanisms for improving results in recovery or maintenance of macular function after retinal detachment surgery.

Submacular Fibrosis After Photocoagulation for Diabetic Macular Edema

Ten eyes of nine patients developed submacular fibrotic scars without fluorescein angiographic evidence of choroidal neovascularization between two and 11 months (mean, 6.1 months) after argon laser treatment for diabetic macular edema. In four eyes, development of the subretinal scar was associated with visual acuity loss of two, two, four, and eight lines of Snellen visual acuity, respectively, within five to 11 months of laser treatment. At the final follow-up visit, the visual acuity of the eyes with two lines of visual acuity loss had returned to within one line of the initial value, but the visual acuity of the eyes with more severe initial visual acuity loss did not recover notably. In four eyes, fibrous submacular strands extended from macular laser scars, suggesting an iatrogenic role of the laser in inducing this complication.

Unilateral Purtscher's Retinopathy

Four patients with unilateral Purtschers retinopathy are described. Fluorescein angiography demonstrated impaired arteriolar flow, capillary non-perfusion, venous staining, retinal edema, and optic disc edema. Resolution exceeded three months with variable degrees of permanent visual loss, optic atrophy, and pigment epithelial alteration. The pathogenesis of Purtschers retinopathy is unknown. Arterial embolization, possibly air from the lungs, seems to be the most plausible explanation.

Outcome and Cost Analysis of Scheduled versus Emergency Scleral Buckling Surgery

BACKGROUND Retinal detachments are usually considered to be a surgical emergency. However, there are additional risks and costs for unnecessary emergency surgeries. The purpose of this study is to evaluate whether the conventional wisdom for treating all retinal detachments as emergencies needs to be re-examined. METHODS Forty-eight patients who had an emergency scleral buckle and 89 patients who had a scheduled procedure were randomly selected from 884 consecutive patients who had a primary scleral buckling procedure during a 4 1/2-year period. The medical records of each patient were used to obtain detailed information related to prognosis. The visual acuity measurements of each patient, taken 6 months after the procedure, were obtained from the records of the ophthalmologist following the patient. Linear regression analysis was used to compare the final visual outcome for patients who had emergency surgery with patients who had scheduled surgery after taking into account patient factors related to prognosis. RESULTS Patients selected for emergency surgery had better visual prognoses than scheduled patients but had the same risk of systemic complications and the same extent of detachment if the macula was not involved. None of the 18 patients with an attached macula experienced macular involvement while awaiting scheduled surgery. There were no differences between emergency and scheduled patients in ocular or systemic complications, rate of reattachment, rate of decreased visual acuity after surgery, visual outcome adjusted for prognosis, or, since 1985, length of hospital stay. A greater cost was incurred for the patients having emergency surgery due to difference in pay scales for support personnel. CONCLUSIONS Because the study is not large and the patients were not randomized to treatment, the results are not definitive. However, they suggest that emergency surgery is unnecessary for many patients with a detached retina.

Direct and Indirect Laser Photocoagulation of Central Serous Choroidopathy

A 3 1/2-year prospective randomized clinical trial showed a definite superiority of direct argon laser photocoagulation to the fluorescein leaking site compared to indirect treatment away from the leak in patients with central serous choroidopathy. One patient in each treatment group developed a subretinal neovascular membrane after photocoagulation to the fluorescein leak. Moderate prolongation of the neurosensory detachment did not adversely influence the final visual acuity in the indirect treatment group. Although direct laser photocoagulation reduces the duration of central serous choroidopathy, there is a risk of producing subretinal neovascularization. The principles of risk vs benefit should be explained to all patients and treatment should be advised only for compelling reasons.

Axial Length Changes after Retinal Detachment Surgery

A-scan echography was an accurate method for detecting changes in the depth of the anterior chamber, lens thickness, and length of the vitreous cavity after retinal detachment surgery in 30 eyes. Approximately 60% of the eyes had significant alterations in axial lengths exceeding+/-0.36 mm in aphakic eyes and +/-0.54 mm in phakic eyes. However, the operation of scleral bucklingg with large segments of hard silicone rubber implants or explants supported by an encircling band failed to result in a significant predictable shift of axial change in phakic or aphakic eyes. A-scan echography showed significant shallowing of the anterior chamber, and scleral buckling significantly increases lens thickness for at least six weeks. This induced a minor myopic refractive change that may explain some of the difference in postoperative refracitons between phakic and aphakic eyes.