Biomedical subjects

T C Burton

Publications and source records attributed to T C Burton.

At least 19 recordsLinked to original sources

PubMed1999

Results after lens extraction in patients with diabetic retinopathy: early treatment diabetic retinopathy study report number 25.

OBJECTIVE: To assess the visual results after surgical lens removal in patients with diabetic retinopathy. DESIGN: A multicenter randomized clinical trial designed to assess the effect of photocoagulation and aspirin in patients with mild to severe nonproliferative or early proliferative diabetic retinopathy and/or macular edema. PARTICIPANTS: Of the 3711 patients enrolled in the Early Treatment Diabetic Retinopathy Study, lens surgery was performed on 205 patients (270 eyes) during follow-up that ranged from 4 to 9 years. OUTCOME MEASUREMENTS: Visual acuity, macular edema status, and degree of diabetic retinopathy. In addition, risk factors associated with lens extraction and with poor postoperative visual acuity (worse than 20/100) were assessed. RESULTS: The risk of lens extraction increased with increasing age, female sex, and baseline proteinuria. Ocular variables associated with increased risk of lens surgery included poor baseline visual acuity and vitrectomy performed during the course of the study. At 1 year after lens surgery, visual acuity improvement of 2 or more lines from preoperative levels occurred in 64.3% of the operated-on eyes assigned to early photocoagulation and 59.3% of eyes assigned to deferral of photocoagulation. In eyes assigned to early photocoagulation, 46% of eyes achieved visual acuity better than 20/40; 73%, better than 20/100; and 8%, 5/200 or worse at 1 year after surgery. Visual acuity results for eyes assigned to deferral of laser photocoagulation at 1 year were not as favorable; 36% achieved visual acuity better than 20/40; 55%, better than 20/100; and 17%, 5/200 or worse at 1 year after surgery. Evaluation of 1-year postoperative visual acuities for all eyes with mild to moderate nonproliferative diabetic retinopathy at the annual visit before lens surgery showed that 53% were better than 20/40; 90%, better than 20/100; and 1%, 5/200 or worse. However, for eyes with severe nonproliferative or worse retinopathy at the annual visit before lens surgery, only 25% were better than 20/40; 42%, better than 20/100; and 22%, 5/200 or worse at 1 year after lens surgery. There was little change in visual acuity between 1 and 2 years postoperatively. Increased severity of retinopathy and poor visual acuity before surgery were associated with visual acuity of worse than 20/100 at 1 year after surgery. Lens surgery was associated with a borderline statistically significant increased risk of progression of diabetic retinopathy in the adjusted analyses (P = .03). No statistically significant long-term increased risk of macular edema was documented after lens surgery. CONCLUSIONS: Visual acuity results after lens surgery in patients in the Early Treatment Diabetic Retinopathy Study were better than published results for similar patients. This may be because of more intensive photocoagulation for lesions of diabetic retinopathy in the Early Treatment Diabetic Retinopathy Study than in previously reported studies. Although patients with severe nonproliferative retinopathy or worse before lens surgery had poorer visual results, visual improvement was seen in 55% of these patients at 1-year follow-up. The main causes of poor visual results in eyes after lens surgery were complications of proliferative retinopathy and/or macular edema.

Aspirin↗

PubMed1999

Clinical course of macular holes: the Eye Disease Case-Control Study.

OBJECTIVE: To describe the clinical course of affected and unaffected eyes in patients with idiopathic macular holes. PATIENTS: Prospective study of patients with macular holes enrolled in the Eye Disease Case-Control Study. MAIN OUTCOME MEASURES: The best-corrected visual acuity at follow-up was compared with that at baseline. Changes in the macular holes, including increases in size or spontaneous regression, were assessed. The rates of development of new macular holes in fellow unaffected eyes were estimated. RESULTS: Of the 198 patients examined at baseline, 28 (14.1%) died before reevaluation. Of those who survived, 122 (71.8%) had a follow-up examination. Approximately 34% (34.4%) of all eyes with macular holes had an increase in the size of the macular hole. Forty-five percent of eyes had a decrease in visual acuity of 2 or more lines and 27.8%, of 3 or more lines; 40.9% remained stable, with a gain or loss of fewer than 2 lines. The rate of development of a new macular hole during follow-up in fellow eyes that were unaffected at baseline was 4.3% for 3 or fewer years of follow-up, 6.5% for 4 to 5 years of follow-up, and 7.1% for 6 or more years of follow-up. Spontaneous regression of the macular hole occurred in 3 (8.6%) of 35 patients with a follow-up interval of 6 or more years, whereas no regression occurred in patients with a shorter follow-up. CONCLUSIONS: The visual acuity of 45.0% of eyes with macular holes deteriorated by 2 or more lines during follow-up. The rate of development of macular holes in unaffected fellow eyes was low.

Adult↗

PubMed1998

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.

Adult↗

PubMed1995

Serum zinc and serum lipid profiles in 778 adults.

There has been increasing use of high-dosage zinc supplementation in the population, in particular as a potential treatment for age-related macular degeneration. We examined the relationship between fasting serum zinc and serum lipid levels in 778 adults, aged 22 to 80 years, who were control subjects in a multicenter, clinic-based case-control study. The samples were taken during 1987 to 1990, a time when vitamin/mineral supplementation was becoming increasingly common. We found that higher serum zinc levels, most notably those above the highest quintile, were associated with higher levels of total serum cholesterol, low-density-lipoprotein cholesterol, and triglycerides. No significant trend was noted for high-density-lipoprotein cholesterol. Previous studies demonstrated that high-dosage zinc supplements raise serum zinc levels. The possibility that use of such supplements can adversely affect serum lipid profiles suggests that chronic ingestion of such supplements should not be done without adequate medical supervision.

Adult↗

PubMed1994

Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group.

OBJECTIVE--To evaluate the relationships between dietary intake of carotenoids and vitamins A, C, and E and the risk of neovascular age-related macular degeneration (AMD), the leading cause of irreversible blindness among adults. DESIGN--The multicenter Eye Disease Case-Control Study. SETTING--Five ophthalmology centers in the United States. PATIENTS--A total of 356 case subjects who were diagnosed with the advanced stage of AMD within 1 year prior to their enrollment, aged 55 to 80 years, and residing near a participating clinical center. The 520 control subjects were from the same geographic areas as case subjects, had other ocular diseases, and were frequency-matched to cases according to age and sex. MAIN OUTCOME MEASURES--The relative risk for AMD was estimated according to dietary indicators of antioxidant status, controlling for smoking and other risk factors, by using multiple logistic-regression analyses. RESULTS--A higher dietary intake of carotenoids was associated with a lower risk for AMD. Adjusting for other risk factors for AMD, we found that those in the highest quintile of carotenoid intake had a 43% lower risk for AMD compared with those in the lowest quintile (odds ratio, 0.57; 95% confidence interval, 0.35 to 0.92; P for trend = .02). Among the specific carotenoids, lutein and zeaxanthin, which are primarily obtained from dark green, leafy vegetables, were most strongly associated with a reduced risk for AMD (P for trend = .001). Several food items rich in carotenoids were inversely associated with AMD. In particular, a higher frequency of intake of spinach or collard greens was associated with a substantially lower risk for AMD (P for trend < .001). The intake of preformed vitamin A (retinol) was not appreciably related to AMD. Neither vitamin E nor total vitamin C consumption was associated with a statistically significant reduced risk for AMD, although a possibly lower risk for AMD was suggested among those with higher intake of vitamin C, particularly from foods. CONCLUSION--Increasing the consumption of foods rich in certain carotenoids, in particular dark green, leafy vegetables, may decrease the risk of developing advanced or exudative AMD, the most visually disabling form of macular degeneration among older people. These findings support the need for further studies of this relationship.

Aged↗

PubMed1992

Progression of nonproliferative diabetic retinopathy and visual outcome after extracapsular cataract extraction and intraocular lens implantation.

Twenty-one patients with symmetric nonproliferative retinopathy who underwent extracapsular cataract extraction and intraocular lens implantation were followed up postoperatively for an average (+/- standard deviation) of 18 +/- 7 months to determine the incidence of progression of diabetic retinopathy, the final visual acuity, and factors predictive of progression of retinopathy and final visual acuity. Progression of retinopathy, defined as the development of clinically significant macular edema, an increase in intraretinal hemorrhages or hard exudate, or the development of proliferative diabetic retinopathy, was assessed in both eyes of 19 patients; in two remaining patients, dense preoperative cataract in the fellow eye precluded comparison of retinopathy progression in the operated-on eye to progression in the fellow eye. Overall, retinopathy progressed in 14 of 19 operated-on eyes (74%). Cataract extraction was highly associated with asymmetric progression of nonproliferative retinopathy; it progressed only in the operated-on eye in seven of 19 patients (37%), but in no patients did progression occur in the fellow eye alone (P = .0078). Women had a significantly increased risk of progression of retinopathy in the operated-on eye compared to men (P = .005). Visual acuity improved in 19 of 21 operated-on eyes (86%); however, only 11 eyes (52%) achieved a visual acuity of 20/50 or better and only six eyes (14%) achieved a visual acuity of 20/25 or better. In only five eyes was the final visual acuity in the operated-on eye more than two lines better than the final visual acuity in the fellow eye.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

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.

Aged↗

PubMed1992

Aspirin effects on the development of cataracts in patients with diabetes mellitus. Early treatment diabetic retinopathy study report 16.

The Early Treatment Diabetic Retinopathy Study, a randomized clinical trial supported by the National Eye Institute, was designed to assess the effect of photocoagulation and aspirin in 3711 patients with mild to severe nonproliferative or early proliferative diabetic retinopathy. Although the primary goal of the study was to evaluate the effect of photocoagulation and aspirin on diabetic retinopathy, the study also provided an opportunity to evaluate the effects of aspirin on the development of cataract. No evidence showed that aspirin use reduced the risk of development of cataract requiring extraction (4.1% vs 4.3% in patients assigned to aspirin or placebo treatment, respectively; Mantel-Cox P = .77; relative risk, 1.05; 99% confidence interval, 0.73 to 1.51). Aspirin use also did not reduce the risk of less extensive but visually significant lens opacities developing (29.6% vs 28.3%; Mantel-Cox P = .76; relative risk, 0.99; 99% confidence interval, 0.85 to 1.15). Early Treatment Diabetic Retinopathy Study results do not support the hypothesis that aspirin (at a dose of 650 mg/d) reduces the risk of cataract development in this diabetic population.

Adult↗

PubMed1992

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%).

Adolescent↗

PubMed1992

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.

Appointments and Schedules↗

PubMed1991

Methanol poisoning. A rodent model with structural and functional evidence for retinal involvement.

Methanol ingestion can lead to visual impairment, central nervous system dysfunction, or death. The extent of ocular involvement has been difficult to determine because the toxicity is restricted to humans and nonhuman primates due to species differences in methanol metabolism. A rodent model of methanol toxicity recently developed by us was used to evaluate retinal dysfunction in methanol poisoning. Formic acidemia and visual toxic reactions developed in methanol-intoxicated rats. Electroretinographic analysis indicated a significant early deficit in b-wave amplitude followed by a temporally delayed, lesser reduction in a-wave amplitude. Histologic evaluation of the eyes 60 hours after methanol administration revealed generalized retinal edema and vacuolation in the photoreceptors and retinal pigment epithelium. Ultrastructural examination showed swelling and disruption of the mitochondria in photoreceptor inner segments, optic nerve, and the retinal pigment epithelium. These studies document direct retinal involvement in this nonprimate model of methanol toxicity.

Animals↗

PubMed1991

Outcome and cost analysis of scheduled versus emergency scleral buckling surgery.

Conventional wisdom holds that a retinal detachment of recent onset should be regarded as a surgical emergency. A delay in surgery may result in an extension of detachment for patients with an attached macula and a worse visual outcome for patients with a detached macula. However, the potential disadvantages of performing surgery on an emergency basis must be weighed against the risks of delaying surgery; disadvantages include a greater frequency of operative complications resulting from fatigue factors among the operating personnel, an increased anesthetic risk due to inadequate time to assess and stabilize coexisting medical problems, and higher hospital costs. In this retrospective study covering 4 1/2 years, we compared the risks, benefits, length of hospitalization, and costs of scleral buckling surgery for retinal detachments performed as an emergency procedure or on the day following admission. After a 15% random selection from 884 consecutive operations, 48 emergency procedures were compared with 89 scheduled procedures. Patients selected for emergency surgery had better visual prognoses than scheduled patients. The potential for risk of systemic complications was not a reason for postponing surgery. 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 following surgery, visual outcome adjusted for prognosis, or, since 1985, length of hospital stay. Cost was greater for patients having emergency surgery, because of a difference in pay scales for support personnel.

Cost-Benefit Analysis↗

PubMed1990

Combined phacoemulsification and pars plana vitrectomy.

Combined phacoemulsification and pars plana vitrectomy were performed in eight eyes with cataract and vitreoretinal disease. Six eyes had tractional retinal detachment and/or nonclearing vitreous hemorrhage, one eye had a retained metallic intraocular foreign body, and one eye had a traumatic retinal detachment. In six eyes, a posterior chamber lens implant was placed in the capsular bag. Postoperative visual acuity improved in each case and ranged between 20/15 and 6/200. There were no perioperative complications, and the posterior chamber lens implant appeared well tolerated during an average follow-up interval of 8 months (range, 3 to 30 months). This technique allows endocapsular fixation of a posterior chamber lens and provides rapid visual rehabilitation with a single operation.

Adult↗

PubMed1990

Complications of primary scleral buckling procedures in high myopia.

Repair of retinal detachments in high myopia may be associated with numerous intraoperative complications. Included are complications involved with the drainage of subretinal fluid as well as those arising from thin sclera. Highly myopic eyes tend to be more prone to these complications than less myopic or nonmyopic eyes. A retrospective study of 51 consecutive highly myopic eyes (six diopters (D) or greater) undergoing primary scleral buckling procedures was performed. Intraoperative complications occurred in a total of six eyes (12%). The complications were related to drainage of subretinal fluid in four eyes (8%) and associated with thin sclera in two eyes (4%). Despite the above-noted complications, there was no adverse effect on the final level of visual acuity or on the anatomic status of the retina. In the comparison of the incidence of drainage-related complications with previously published studies not preselected according to refractive status, there appears to be no added risk of complications based on the degree of myopia.

Adolescent↗

PubMed1989

The influence of refractive error and lattice degeneration on the incidence of retinal detachment.

This study indicates the feasibility of stratifying the general population into various risk pools for retinal detachment depending on a person's age, refractive status, and the presence of lattice degeneration. At first impression the risks seem at variance with the fine clinical studies of Byer, who has shown a very low detachment rate in the population with lattice degeneration. In all likelihood the vast majority of his patients were emmetropic or mildly myopic, so that very few would be expected to develop detachments during their entire lifetimes, let along during intervals of only 10 to 20 years. This study shows the futility of following, or treating prophylactically, young emmetropic individuals with lattice degeneration. Assuming that prophylaxis is actually effective, one would have to treat 1000 emmetropic lattice patients in the 30 to 39 year age group to prevent a single detachment over a 10-year period. Lattice patients with low to moderate degrees of myopia tend to develop detachments between 40 and 60 years of age caused by premature posterior vitreous separation and tractional tears. Clearly prophylaxis for this group is not warranted, since only 5% to 10% of these individuals will experience detachments in their lifetimes. On the other hand this study has verified the previous suspicions that persons with myopia exceeding -5.0 D accompanied by lattice degeneration have an extraordinarily high risk of detachment during their lifetimes. Detachments in this group tend to cluster in the second, third, and fourth decades, are typically caused by atrophic holes, are slowly progressive, and are often simultaneously bilateral. Enhanced vigilance is certainly appropriate during this time and perhaps consideration should be given to prophylactically treating this group. This would be no small task, since within a population of 1 million persons there would be about 1150 aged 10 to 39 years with myopia exceeding -5.0 D and lattice degeneration. Only 4 detachments annually and 40 detachments in 10 years would be expected in this highest risk group.

Adolescent↗

PubMed1988

Progression of nonproliferative diabetic retinopathy following cataract extraction.

Eight patients experienced progression of nonproliferative diabetic retinopathy following cataract extraction. Six patients underwent an uncomplicated extracapsular cataract extraction with placement of a posterior chamber intraocular lens, and in two patients, surgery was complicated by vitreous loss. In each case the retinopathy progressed to a severe exudative form of diabetic macular edema, characterized by diffuse retinal thickening and fluorescein leakage with increased dot and blot hemorrhages and lipid deposition. In all patients, clinically significant macular edema developed in the eye that had been operated on, and six patients received laser photocoagulation for this condition. Final visual acuity was worse than preoperative visual acuity in six of eight patients, and it was unchanged in two of six patients. No patient achieved a visual acuity better than 20/50. The fellow eyes, which were not operated on, remained stable during the follow-up period.

Aged↗

PubMed1988

Laser iris retraction for angle-closure glaucoma after retinal detachment surgery.

Twelve patients with retinal detachment with postoperative angle closure due to ciliary body edema, refractory to topical cycloplegics and corticosteroids, were managed by peripheral iris retraction with argon laser photocoagulation. This gonioscopic procedure results in immediate visualization of angle structures and prompt reduction of intraocular pressure (IOP). Routine tonometry and appropriate gonioscopy are essential to diagnose this form of glaucoma, which does not have a pupillary block component. Timely use of laser iris retraction reduces the risk of chronic glaucoma secondary to synechial closure. In this series, only two of ten patients, not previously known to have glaucoma, require long-term medication to control IOP.

Aged↗

PubMed1986

Management of postoperative suprachoroidal hemorrhage with continuous-infusion air pump.

Seven patients suffered delayed nonexpulsive suprachoroidal hemorrhages following filtration procedures. Six of seven eyes were aphakic, while the seventh had a subluxated lens associated with aniridia. In six of the seven cases, the hemorrhagic choroidal detachments completely filled the posterior segment, and visual acuity was reduced to light perception only. Surgical drainage of the hemorrhages was accomplished through one or two sclerotomies with simultaneous air insufflation of the eye through a limbal needle attached to a continuous-infusion air pump. With this technique, visual acuity was restored to a level equal to or better than the prefiltration acuity in five of seven patients. One patient suffered a slight decline in acuity from 20/60 to 20/100, and another patient's visual acuity declined from finger counting at 5 cm to hand motions.

Adult↗