Alan F. Cruess

Visual Results Following Cobalt Plaque Radiotherapy for Posterior Uveal Melanomas

Visual results of cobalt plaque radiotherapy on the eyes of 77 patients with posterior uveal melanoma in one eye and pretreatment visual acuity of 20/25 or better in both eyes were analyzed using actuarial methods. The study demonstrated that eyes receiving a radiation dose in excess of 5,000 rad to the fovea and/or optic disc commonly lose a substantial amount of vision within 2 to 3 years. It also showed that eyes treated by cobalt plaque radiotherapy for a large posterior uveal melanoma are more likely to suffer profound visual loss than those treated for a medium or small melanoma. The predominant cause of severe visual loss in these patients appeared to be foveal radiation retinopathy.

Reliability of the time trade-off technique of utility assessment in patients with retinal disease

Abstract Background: Studies in medical fields other than ophthalmology have given conflicting results regarding the reliability of the time trade-off technique of utility assessment. We performed a study to determine the test-retest reliability of the time trade-off technique for assessing utilities in patients with ocular diseases of the retina and to investigate possible factors associated with differences in utility over time. Methods: Patients referred to the retina service of a tertiary care hospital in eastern Canada were eligible for the initial interview if they had best corrected vision of 20130 or worse in at least one eye and were deemed competent to answer the required questions. Patients were interviewed prospectively between December 1999 and March 2000 during a normal 30-minute period needed for pharmacologic mydriasis to occur. Demographic, clinical (including Snellen visual acuity) and time trade-off utility information was collected through chart review and standardized interview. Patients who completed the interview successfully were called back 28 days later for follow-up. Results: Of the 138 eligible patients 112 (81.2%) completed the initial interview. Of the 112, 96 (85.7%) completed the second interview. Half of the respondents were women, and all but one respondent were white. The mean age was 65.3 years. The primary reasons for visual loss included diabetic retinopathy (59 patients [61.4%]) and age-related macular degeneration (14 patients [14.6%]). The intraclass correlation coefficient between the initial and follow-up visual utilities was 0.7634 (95% confidence interval 0.6655–0.8355). Interpretation: Our results show excellent reliability of the time trade-off technique of utility assessment in patients with ocular diseases of the retina.

Cilioretinal artery obstruction.

The cases of 23 patients with untreated cilioretinal artery obstruction were reviewed. Three distinct groups were found: (1) isolated cilioretinal artery obstruction, (2) cilioretinal artery obstruction associated with central retinal venous obstruction, and (3) cilioretinal artery obstruction in conjunction with ischemic optic neuropathy. In the first group 90% of eyes achieved 6/12 or better vision and there was a high incidence of associated atherosclerotic carotid disease. In the second group, 70% of eyes improved to 6/12 or better, while in the last group no eye reached better than 6/120 vision.

Peripheral Circumferential Retinal Scatter Photocoagulation for Treatment of Proliferative Sickle Retinopathy

Twenty-nine patients (40 eyes) with proliferative sickle retinopathy (PSR) were treated with circumferential argon laser scatter photocoagulation to zones of peripheral retinal capillary nonperfusion. Each eye was examined in a prospective fashion, with a mean follow-up of 1.4 years. Following scatter treatment, 26% of the pre-existing sea fans regressed completely, 57% regressed partially, 17% remained stable, and none showed progression. In only one eye did de novo neovascularization develop. The results compare favorably with the natural history of PSR (Condon et al, 1980), in which de novo lesions occurred in 58%, and the visual acuity was decreased to less than 20/200 in 12% of affected eyes. Severe iatrogenic complications reported following direct focal treatment of sea fans, such as vitreous hemorrhage, progressive traction retinal detachment, retinal breaks, and choroidal-retinal-vitreal neovascularization were virtually eliminated.

Accuracy of visible retinal emboli for the detection of cardioembolic lesions requiring anticoagulation or cardiac surgery

AIM To determine the accuracy of visible retinal emboli as a diagnostic “test” for the likelihood of receiving anticoagulation or cardiac surgery based on the results of transthoracic echocardiography, in the setting of acute retinal arterial occlusion. METHODS A multicentre retrospective diagnostic study at Kingston Eye Centre, Queen’s University, Kingston, Ontario; Wills Eye Hospital, Philadelphia; Ottawa Eye Institute, Ottawa, Ontario; and the Halifax Infirmary, Halifax, Nova Scotia of 104 patients with both embolic and non-embolic acute retinal arterial obstruction who underwent transthoracic echocardiography was performed, to determine the accuracy of visible retinal emboli as a diagnostic “test” for anticoagulation or cardiac surgery. Anticoagulation or surgical intervention on the basis of abnormalities was detected solely through the technology of transthoracic echocardiography. RESULTS 41 patients had visible retinal emboli (calcific, cholesterol, or fibrin). The remaining 63 had no evidence of embolic disease. The sensitivity of emboli for the likelihood of a patient receiving anticoagulation or cardiac surgery was 50%. The specificity, positive predictive value, and negative predictive value were 62%, 15%, and 90%, respectively. The likelihood ratio (LR=1.31) obtained given the presence of a visible retinal embolus was neither clinically nor statistically significant (LR+ve = 1.31; 95% CI (0.91, 3.16)). This likelihood ratio, when applied to a patient with a pretest probability of 50%, results in a post-test probability of 56.7%. CONCLUSIONS These results demonstrate that the presence of a visible retinal embolus should not be the sole determinant of whether to order transthoracic echocardiography, as the likelihood ratio for a patient receiving anticoagulation or cardiac surgery, given the presence of a visible retinal embolus was only 1.31.

Chloroquine Retinopathy: Is Fluorescein Angiography Necessary?

Color fundus photographs and corresponding fluorescein angiograms from 83 patients suspected of having chloroquine retinopathy were reviewed in a retrospective masked study to determine the relative sensitivity of these two photographic methods in the diagnosis of retinal toxicity. We identified retinal toxicity on both color photographs and fluorescein angiograms in 7.6% of cases, on the color photographs but not on the corresponding angiograms in 6.1% of cases, and on the fluorescein angiograms but not on the color photographs in 1.5% of cases. Fluorescein angiography may not be as sensitive as color fundus photography (or ophthalmoscopy) in the diagnosis of chloroquine retinopathy.

Ophthalmomyiasis treated by argon-laser photocoagulation.

A live, subretinal fly larva was observed in a 16-year-old Caucasian female. Argon-laser photocoagulation killed the larva without a destructive inflammatory response. The patients vision improved from 20/200 to 20/20 as the eye recovered. Clinical photographs demonstrate the larva and the acute and later healed pathopneumonic subretinal tracks. The laser photocoagulation technique is described. RETINA 4:163-165, 1984

Indocyanine green angiography: an evaluation of image enhancement for the identification of occult choroidal neovascular membranes.

PURPOSE To determine the diagnostic yield of occult choroidal neovascularization from examination of nonenhanced digital indocyanine green (ICG) angiograms versus examination of both nonenhanced and contrast-enhanced angiograms. METHODS Fifty consecutive occult choroidal neovascular membranes were examined using ICG angiography at the Queens University Eye Department. These studies were retrospectively reviewed in a masked fashion using the nonenhanced images. A subsequent examination of the same images was then performed using both the nonenhanced and contrast-enhanced images. Each study was graded as focal hyperfluorescence, plaque hyperfluorescence, isofluorescence, or hypofluorescence. RESULTS Of the cases reviewed, only 36% (18/50) of the membranes were well-defined on nonenhanced ICG angiography, compared with 58% (28/50) using image enhancement in addition to the nonenhanced images. This was a statistically significant difference in image definition between the two groups (chi-square test; P < 0.005). CONCLUSION Contrast-enhanced angiograms, when used in conjunction with nonenhanced ICG images, allowed for a significantly higher diagnostic yield when compared with the study of nonenhanced images alone.

Peripheral retinal neovascularization in diabetes mellitus

The cases of seven patients with diabetes mellitus and peripheral proliferative retinopathy (retinal neovascularization at or anterior to the equator) were studied. Associated abnormalities found included systemic arterial hypertension in five, a positive fluorescent treponemal antibody titer in four, and benign monoclonal gammopathy, intravenous drug abuse and hemoglobin AS each in one patient. The presence of additional systemic diseases should be suspected in diabetic patients with predominantly peripheral proliferative retinopathy.

Metamorphosis of retinal exudation following argon laser photocoagulation of retinal telangiectasia.

The authors report a case of retinal telangiectasia in which numerous spheroidal, presumably lipid bodies formed within the subretinal space and in instances migrated within the subretinal space and into the vitreous following argon laser photocoagulation to the anomalous retinal vessels.