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

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 20/30 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.

The prevalence of diabetes in the Cree of western James Bay.

Diabetes prevalence and general demographic data for individuals with diabetes were evaluated in the Cree of Moose Factory, Ontario. Individuals with diabetes were identified through a retrospective review of the diabetes registry as well as of outpatient and inpatient records. The crude prevalence of diabetes was 62 (95% confidence interval: 54 72) per 1,000. The direct age-standardized prevalence of diabetes was 103 per 1,000 for the entire population (95% confidence interval: 89 118 per 1,000, standardized to the 1991 Canadian population). The estimated rate of diabetes in the Canadian population is approximately 5%. The average age of individuals with diabetes in the community was 53 years; the average duration of diabetes was 8.2 years. Most of the population with diabetes were female (64 %) and were using anti-hypertensive medications (64%). This study presents diabetes prevalence data for the population of Moose Factory, Ontario, that indicate a higher prevalence than in both the Canadian population and other Cree populations in the region.

The importance of qualitative vitreous examination in patients with acute posterior vitreous detachment.

OBJECTIVE: To determine whether patients with acute posterior vitreous detachment with pigmented vitreous granules or hemorrhage have a higher likelihood of retinal tear compared with those with qualitatively normal vitreous examination findings. METHODS: A multicenter cross-sectional study was performed in 3 peripheral ophthalmic clinics. Patients with acute posterior vitreous detachment were examined for the presence or absence of vitreous pigment granules, vitreous hemorrhage, and horseshoe retinal tear. RESULTS: Fifty-nine consecutive patients with acute posterior vitreous detachment met our eligibility criteria. Eight patients had a retinal tear, and thus its prevalence in our study was almost 14%. Thirteen patients (22%) had a high likelihood because they had evidence of either pigmented vitreous granules or hemorrhage. The prevalence of retinal tear in the setting of acute posterior detachment associated with vitreous hemorrhage alone, pigment alone, or vitreous hemorrhage and pigment was 54%. Patients with posterior vitreous detachment with pigmented vitreous granules or hemorrhage were significantly more likely to have a retinal tear (odds ratio, 52.0; 95% confidence interval, 5.4-497.0). Patients with a retinal tear were 7 times more likely to have pigmented vitreous granules or hemorrhage (LR + ve = 7.4, in which LR + ve indicates positive likelihood ratio; 95% confidence interval, 3.3-16.4). CONCLUSION: Patients with posterior vitreous detachment with vitreous pigment granules or hemorrhage are 52 times more likely to have a retinal tear compared with those who have normal findings on qualitative vitreous examination.

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 Queen's 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.

Does a visible retinal embolus increase the likelihood of hemodynamically significant carotid artery stenosis in patients with acute retinal arterial occlusion?

OBJECTIVE: To determine the value of visible retinal emboli as a diagnostic "test" for the detection of hemodynamically significant carotid artery stenosis in the setting of acute retinal artery occlusion. METHODS: A cross-sectional diagnostic accuracy study was performed in a tertiary North American center, with the results of the dichotomous diagnostic test (the presence or absence of visible retinal emboli) being placed against the dichotomous outcome of the presence or absence of hemodynamically significant carotid artery stenosis (defined as > or = 60%, or < 60%, carotid artery stenosis on either side). RESULTS: Forty-eight (18.7%) of our 256 patients had hemodynamically significant carotid artery stenosis. The sensitivity and specificity of retinal emboli for the detection of hemodynamically significant carotid artery stenosis were 39% and 68%, respectively. The presence of a visible retinal embolus generated a likelihood ratio of 1.24 (95% confidence interval, 0.84-1.86). This value corresponds to a patient with a pretest probability of 50% having a posttest probability of 55.3%. The absence of a visible retinal embolus generated a likelihood ratio of 0.88 (95% confidence interval, 0.68-1.15). CONCLUSIONS: The presence of a visible retinal embolus is a poor diagnostic test for the detection of hemodynamically significant carotid artery stenosis in the setting of acute retinal artery occlusion. Accordingly, the presence of an embolus should not influence the decision to perform carotid Doppler ultrasonography in patients with acute retinal arterial occlusion.

Accuracy of visible retinal emboli for the detection of cardioembolic lesions requiring anticoagulation or cardiac surgery. Retinal Emboli of Cardiac Origin Study Group.

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 nonembolic 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.

Crystalline retinopathy associated with chronic retinal detachment.

OBJECTIVE: To describe the presence of crystalline opacities located at the level of the inner retina in patients with chronic retinal detachment. METHODS: We reviewed the clinical records, fundus photographs, and fluorescein angiograms of patients with superficial retinal crystals in the presence of a chronic retinal detachment. RESULTS: Eleven eyes in 11 patients with chronic retinal detachment were found to have these peculiar crystalline opacities on the inner retinal surface. In 5 patients, the crystalline opacities were noted on initial assessment prior to surgery and persisted without change in appearance or number after surgical repair. In 6 eyes, the crystals were not appreciated until after surgical repair of the retinal detachment. The crystals appeared similar in all 11 eyes, were highly refractile, and were located in the posterior pole. Eight of the eyes had retinal detachment associated with retinal dialysis and 6 of these had a history of trauma. There was a definite history of vitreous hemorrhage in 2 eyes. The crystals did not seem to be associated with any visual deficit. CONCLUSIONS: Chronic retinal detachment can be associated with crystals on the inner retinal surface. The cause and composition of these crystals are unknown. They seem to be visually inconsequential and unchanging.

Can different types of retinal emboli be reliably differentiated from one another? An inter- and intraobserver agreement study.

OBJECTIVE: To determine whether ophthalmologists can agree on the qualitative assessment of visible retinal emboli. DESIGN: Inter- and intraobserver agreement study. SETTING: The retina and vitreous subspecialty session at the 1996 Canadian Ophthalmological Society meeting. SUBJECTS: A total of 42 observers, of whom 30 were retinal specialists. OUTCOME MEASURES: The observers viewed 17 fundus photographs of 11 patients with embolic acute retinal artery occlusion and classified the visible retinal emboli into one of three groups: cholesterol, calcific or other. RESULTS: Overall, there was slight agreement for the 17 observations (mean kappa = 0.063). The kappa statistic for all cases ranged from slight to fair agreement. Slight interobserver agreement for the six unique photographs was observed (mean kappa = 0.073). Slight intraobserver agreement was found for the three photographs that were shown in different orientations (mean kappa = 0.041) and for the two photographs shown with differing magnification (mean kappa = 0.102). CONCLUSIONS: Overall both intraobserver and interobserver agreement on the qualitative assessment of retinal emboli was poor. With only slight agreement on the classification of emboli, systemic evaluation of acute retinal artery occlusion should not be based on qualitative assessment of retinal emboli.

Transthoracic echocardiography in young patients with acute retinal arterial obstruction. RECO Study Group. Retinal Emboli of Cardiac Origin Group.

OBJECTIVE: To report the transthoracic echocardiographic findings in young patients presenting with acute retinal arterial obstruction, given their clinical risk status for cardioembolic disease. DESIGN: Case series. SETTING: Four North American tertiary hospital centres. PATIENTS: Eleven patients less than 45 years of age presenting with acute retinal arterial obstruction who underwent transthoracic echocardiography. OUTCOME MEASURES: Anticoagulation therapy or cardiac surgery. RESULTS: Echocardiography showed abnormalities in five patients (45%). Five of the 11 patients were at high risk for cardioembolic disease on the basis of a history of risk factors or the presence of a cardiac murmur on presentation, or both. Three (60%) of the five had abnormal findings on echocardiography; all three required anticoagulation therapy or cardiac surgery. Of the six patients at low risk two (33%) had abnormal echocardiograms; neither required anticoagulation therapy or surgical intervention. CONCLUSIONS: All the patients who required anticoagulation therapy or cardiac surgery based on the findings on transthoracic echocardiography were deemed to be at high risk for cardioembolic disease. This emphasizes the importance of clinical risk stratification in the systemic evaluation of young patients presenting with acute retinal arterial obstruction.

Interobserver agreement in the evaluation of acute retinal artery occlusion.

OBJECTIVE: To determine the agreement between two ophthalmologists in the evaluation of two important funduscopic features related to acute retinal artery occlusion: retinal cloudy swelling and visible retinal emboli. DESIGN: An interobserver variability study in which two ophthalmologists (one trained in glaucoma, the other in neuro-ophthalmology) independently viewed fundus photographs and categorized them with respect to the presence or absence of cloudy swelling and retinal emboli. Inter- and intraobserver agreement was calculated with the kappa statistic. SETTING: Retina service at a university-affiliated hospital in Kingston, Ont. PATIENTS: The fundus photographs of 102 patients were included: 60 with acute retinal artery occlusion, 30 with conditions mimicking acute retinal artery occlusion and 12 healthy patients. RESULTS: Both interobserver and intraobserver agreement as to the presence of retinal cloudy swelling were very high (kappa = 0.835 and 0.866 respectively). More variability was seen for the presence of retinal emboli, but, overall, interobserver and intraobserver agreement were still high (kappa = 0.726 and 0.629 respectively). CONCLUSIONS: Our results suggest that clinicians use similar visual clues to categorize fundi with respect to retinal cloudy swelling and visible retinal emboli.

Transthoracic echocardiographic findings in patients with acute retinal arterial obstruction. A retrospective review. Retinal Emboli of Cardiac Origin Group.

OBJECTIVE: To assess the importance of cardio-embolic (emboli of cardiac origin) risk stratification in the cardiac evaluation of patients with acute retinal arterial obstruction. DESIGN: A multicenter retrospective study of patients with acute retinal arterial obstruction who underwent transthoracic echocardiography. SETTINGS: Four North American hospital centers. PATIENTS: One hundred patients with acute retinal artery obstruction in whom transthoracic echocardiography was performed. MAIN OUTCOME MEASURE: Anticoagulation or cardiac surgery based on abnormalities detected on transthoracic echocardiography. Transesophageal echocardiographic results were not evaluated, as they were rarely performed in our centers. Thus, the outcome measure was determined solely by the results of transthoracic echocardiography. RESULTS: Patients were divided into high- and low-risk groups based on their history of cardioembolic risk factors or the presence of a cardiac murmur. Of 67 patients with no risk factors, 41 (61%) had normal echocardiographic study results and 26 (39%) had abnormalities detected, of whom only 1 (1.5%) received anticoagulation or cardiac surgery. The presence of 1 or more cardio-embolic risk factors increased the likelihood for anticoagulation or cardiac surgery 25 times (odds ratio = 25; 95% confidence interval = 3.04-217.02). Although this result is clinically and statistically significant, it is possible that abnormalities missed by transthoracic methods may have been detected by transesophageal technology. CONCLUSIONS: In patients with acute retinal arterial obstruction at low cardioembolic risk, transthoracic echocardiography resulted in anticoagulation or cardiac surgery in 1 (1.5%) of 67 patients. Routine transthoracic echocardiography without follow-up transesophageal echocardiography for patients identified as having abnormalities such as left ventricular hypertrophy or mitral annular calcification and who are at low cardioembolic risk rarely resulted in anticoagulation or cardiac surgery.

Argon green vs. krypton red laser photocoagulation for extrafoveal choroidal neovascularization secondary to age-related macular degeneration: 3-year results of a multicentre randomized trial. Canadian Ophthalmology Study Group.

OBJECTIVE: To determine whether argon green laser (AGL) or krypton red laser (KRL) is superior for the treatment of well-defined extrafoveal choroidal neovascularization (CNV) in patients with age-related macular degeneration (AMD) after 3 years of follow-up. DESIGN: Multicentre randomized clinical trial. SETTING: University-based referral practices in Canada. PARTICIPANTS: Among 210 patients selected by ophthalmologists at 13 participating centres there were 191 eligible patients aged 50 years or more with angiographically proven CNV whose posterior edge was 200 to 2500 microns from the foveal avascular zone. Other inclusion criteria included the presence of drusen in either eye, a best corrected visual acuity in the study eye of at least 35 letters on the Early Treatment Diabetic Retinopathy Study chart (equivalent of 20/200 or better on the Snellen chart) and no prior photocoagulation in the study eye. The patients were randomly assigned to receive either AGL (96 patients) or KRL (95 patients) treatment. INTERVENTIONS: Treatment with 200-microns spots of 0.2 to 0.5 seconds' exposure to produce a homogeneous grey white lesion that completely covered the CNV. OUTCOME MEASURES: Change from baseline in visual acuity at 1, 2 and 3 years (primary measure), development of persistent or recurrent CNV (secondary measure). RESULTS: There were no significant differences between the treatment groups in drop-out rates. No significant differences were found between the two groups in loss of visual acuity or angiographic evidence of persistent or recurrent CNV. CONCLUSION: KRL is no better than AGL in preserving vision and preventing loss of visual acuity in patients with AMD with well-defined extrafoveal CNV followed for 3 years.

Chronic benign retinal pigment epithelial detachment: a subtype of central serous choroidopathy.

Between October 1983 and December 1991, 14 patients (mean age 48.1 [range 38 to 68] years) presented with single, clear, cystic-appearing juxtafoveal lesions beneath the retina, with discrete borders measuring approximately 2 mm in diameter. All patients had vision of 6/7.5 or better, which did not deteriorate over a follow-up period of 3 to 91 (mean 18.1) months. Angiographically, the lesions showed relative homogeneous hyperfluorescence with very discrete margins, the angiographic appearance of serous retinal pigment epithelial detachment. We describe the clinical and angiographic appearance on presentation and in follow-up and discuss the probable relationship of these lesions to central serous choroidopathy.

Clinical trials: where do we go from here?

Randomized clinical trials are necessary to detect a possible treatment effect of interventions for which no clear-cut answer is known. In ophthalmology, clinical trials have shown the benefit of laser therapy in several eye diseases. As smaller treatment effects are sought, sample sizes must be increased considerably to maintain statistical power. This can be done only through multicentre randomized clinical trials. Provided the question being asked is of value to society, the cost of a clinical trial is an excellent investment.

Argon green and krypton red laser treatment of diabetic macular edema.

We treated 69 eyes of 44 patients who had clinically significant macular edema with argon or krypton laser photocoagulation or both. The mean initial visual acuity was 20/40. Patients were followed for 6 to 63 (mean 19.7 +/- 11.0) months. There was a mean loss of three letters in acuity, but the difference between initial and final acuity was not statistically significant. In 43 eyes the acuity remained within two lines of the initial acuity, in 17 there was a loss of two lines or more, and in 9 the acuity improved by two lines or more. The initial acuity correlated highly to the final acuity (p less than 0.0001). Multiple linear regression showed that pretreatment existence of macular ischemia or diffuse macular edema or both, when adjusted for initial acuity, age, insulin dependence and duration of diabetes mellitus, was predictive of poorer final acuity than in patients without ischemia or diffuse edema. The results support a consensus that macular edema should be treated early. In view of the conflicting experimental and clinical studies of grid techniques of photocoagulation and the role of the krypton laser, further clinical studies of the treatment of diabetic macular edema are warranted.