Marvin J. Podgor

Age and illuminance effects in the Farnsworth-Munsell 100-hue test

Seventy-five normal volunteers (20-78 yr) were tested on the Farnsworth-Munsell 100-hue test at each of five illuminance levels. Each cap score distribution was analyzed by fitting a two-cycle sine wave whose amplitude and phase characterize the polarity of the error distribution and its axis. Analysis of these parameters reveals a similarity between tritanlike defects in older groups and those of younger groups at lower illuminance levels. These data are also useful for specifying age norms for the polarity of the error distribution.

A longitudinal study of body mass index and lens opacities: The Framingham studies

OBJECTIVE The purpose of the study was to determine whether body mass index (BMI) is an independent risk factor for the development of nuclear, cortical, or posterior subcapsular lens opacities. DESIGN A cohort study. PARTICIPANTS AND METHODS Eye examinations were conducted on surviving members of the Framingham Heart Study Cohort from 1973 to 1975 (Framingham Eye Study I) and again from 1986 to 1989 (Framingham Eye Study II). Data from the Framingham Heart Study, including weight measurements collected biennially from 1948, were used to examine associations between BMI (mean BMI across examinations, slope of BMI over time, and fluctuations in BMI) and the development of lens opacities. This analysis included 714 individuals, aged 52-80 years, who were free of lens opacities at the first eye examination. MAIN OUTCOME MEASURES Development of nuclear, cortical, and posterior subcapsular lens opacities. RESULTS A total of 444 persons developed lens opacities during the approximately 13 years between eye examinations. In logistic regression analyses that controlled for age, sex, education, diabetes, and smoking, the risk of developing cortical opacity increased with higher BMI at the time of the first eye examination (P = 0.002). Risk of cortical opacities also increased, at a borderline level of significance, with higher average BMI (P = 0.09) across examinations and increasing BMI levels over time (P = 0.10). There was a strong association between increasing BMI over time and the development of posterior subcapsular lens opacities (P = 0.002). No associations were found for nuclear lens opacities. CONCLUSIONS Although the mechanism explaining the association is unclear, these findings suggest that BMI, a potentially modifiable characteristic, is associated with the development of cortical and posterior subcapsular lens opacities.

Macular Edema in Diabetic Retinopathy Study Patients: Diabetic Retinopathy Study Report Number 12

Results from the Diabetic Retinopathy Study (DRS) demonstrate that scatter photocoagulation is associated with some loss of visual acuity soon after treatment. This visual loss is especially prominent in eyes with preexisting macular edema. It is also associated with the intensity of treatment. Reducing macular edema by focal photocoagulation before initiating scatter treatment and dividing scatter treatment into multiple sessions with less intense burns may decrease the risk of the visual loss associated with photocoagulation.

Lens Changes and Survival in a Population-Based Study

The Framingham Heart Study was begun in 1948 to study factors associated with cardiovascular disease. Participants have been reexamined approximately every two years. From 1973 to 1975, the Framingham Eye Study examined the eyes of available Heart Study participants. We used information about nearly 2000 persons from these population-based studies to investigate the relation of lens changes to survival. Follow-up ranged from five to eight years; 312 persons (16 per cent) died. Proportional-hazards regression analyses indicated an overall association of lens changes and decreased survival (P = 0.01), but detailed investigation showed (1) no association of lens changes and decreased survival among persons without diabetes (P = 0.29) and (2) a significant association of lens changes and decreased survival among persons with diabetes (P = 0.001). Diabetic persons with lens changes had an estimated death rate more than twice that of diabetics without lens changes. The duration of diabetes and degree of retinopathy were not associated with survival in this group, most of whom had adult-onset diabetes of short duration. We conclude that lens changes are earlier predictors of death in diabetics than these more traditional variables.

A randomized, masked, crossover trial of acetazolamide for cystoid macular edema in patients with uveitis

PURPOSE To study the effect of acetazolamide on cystoid macular edema in patients with uveitis. METHODS Forty patients with chronic intermediate, posterior, or panuveitis associated cystoid macular edema were randomized into a masked, cross-over trial comparing acetazolamide versus placebo. Patients received an initial 4-week course of either acetazolamide or placebo (course A) followed by a 4-week washout period. They then received a 4-week course of the opposite study medication (course B). Primary endpoints included area of cystoid macular edema measured on late-phase views of fluorescein angiography and visual acuity. RESULTS Thirty-seven patients completed the trial and were available for analysis; 17 (46%) were randomized to receive acetazolamide and 20 (54%) to receive placebo during course A. Acetazolamide resulted in a 0.5-disc area (25%) decrease in cystoid macular edema over that of placebo (P = 0.01; estimated treatment effect = -0.5 disc areas; 95% confidence interval, -0.9 to -0.1). However, there was no statistically significant effect of acetazolamide on visual acuity (P = 0.61; estimated treatment effect = 0.6 letters; 95% confidence interval, -2 to 3). CONCLUSIONS A 4-week course of acetazolamide therapy results in a statistically significant but small decrease in cystoid macular edema in patients with chronic uveitis, and does not improve visual acuity. In contrast to previous studies in the literature, acetazolamide may have a more limited clinical benefit in patients with long-standing cystoid macular edema associated with chronic uveitis.

High intraocular pressure and survival: the Framingham studies☆

PURPOSE To examine whether high intraocular pressure (greater than or equal to 25 mm Hg) or a history of treatment for glaucoma is associated with decreased survival and, if so, how such ocular markers might be explained. METHODS Eye examinations, including applanation tonometry, were conducted on members of the Framingham Eye Study cohort from February 1, 1973, to February 1, 1975. Participants who reported a history of treatment for glaucoma were identified. Survival data, including information on the date of death, were available from the time of the Eye Study through March 31, 1990. RESULTS Of the 1,764 persons under the age of 70 years at the baseline eye examination, 1,421 persons had low intraocular pressure (< or =20 mm Hg), 264 persons had medium intraocular pressure levels (20 to 24 mm Hg), and 79 persons had high intraocular pressure (> or =25 mm Hg) or history of glaucoma treatment. During the follow-up period, 29%, 30%, and 47% died in the groups with low, medium, and high intraocular pressure (or history of glaucoma treatment), respectively. In an age-and-sex adjusted Cox proportional hazards analysis, the death rate ratio for the group with medium intraocular pressure relative to the group with low intraocular pressure was 1.04. The corresponding death rate ratio for the group with high intraocular pressure was 1.56 with a 95% confidence interval of 1.11 to 2.19 (P < .001). After adjustment for age, sex, hypertension, diabetes, cigarette smoking, and body mass index, a positive relationship remained, but at a borderline level of significance (P = .075). CONCLUSIONS High intraocular pressure or the presence of glaucoma is a marker for decreased life expectancy in the Framingham Eye Study cohort. The relationship is present even after adjustment for risk factors known to be associated with higher mortality such as age, sex, hypertension, diabetes, cigarette smoking, and body mass index. Special attention to the general health status of patients with high intraocular pressure or glaucoma seems warranted.

Color vision and age in a normal North American population

Color vision is known to change with age. We conducted the Farnsworth-Munsell (FM) 100-Hue and the Lanthony Desaturated Panel D-15 (DD-15) tests in 115 normal North American subjects aged 5–81 years to obtain age-specific norms for these procedures. For each test, color discrimination was best between the ages of 20 and 50 years. Both increasing age and the occurrence of lens changes were significantly associated with increasing 100-Hue error scores. Age-specific norms for the 100-Hue test were comparable with those obtained by Verriest in a European population, but such norms for the DD-15 test are problematic. Our data indicate somewhat greater variability in the DD-15 than in the 100-Hue test.

A comparative study between the PAM and the laser interferometer in cataracts

We conducted a prospective study on 35 consecutive eyes undergoing cataract extraction to compare the Guyton-Minkowski Potential Acuity Meter (PAM) and the Laser Interferometer (LI) in determining potential visual acuity. The eyes were divided into: group A, which had good visualization of optic disc details, and group B, whose media allowed only disc outline or less to be seen. We found that in group A eyes, both instruments were reliable (with accuracies of 94% for the PAM and 88% for the LI). However, in group B eyes (advanced cataracts), both instruments were unreliable (accuracies of 33% for the PAM and 53% for the LI). Interestingly, in a subgroup of high myopes (axial length >29 mm) with moderate cataracts and poor visual acuties, both instruments were very reliable and helpful in determining how much of the vision loss was due to the cataracts. We therefore strongly recommend potential acuity testing in high myopes with moderate cataracts and poor visual acuity.

Contrast and Glare Sensitivity: Association with the Type and Severity of the Cataract

PURPOSE Contrast and glare sensitivity tests are now being used as adjuncts to visual acuity in the assessment of visual function. Limited data are available on the associations of the former tests with cataract type and severity. The aim of the study is to assess these associations using standardized techniques. METHODS Contrast sensitivity tests (using the Pelli-Robson chart) and glare sensitivity tests (using the Vistech MCT 8000) were done on 128 patients with cataracts and no other ocular disease and on 29 control volunteers. The cataracts were graded using the Lens Opacities Classification System II (LOCS II). Data from the left eyes were analyzed using logistic regression models. RESULTS Contrast sensitivity loss was associated with cataract severity for cortical (P less than 0.0001) and posterior subcapsular (P = 0.0001) cataracts and with decreased visual acuity (P = 0.0001). Night and day glare sensitivity were each associated only with increased severity of posterior subcapsular cataracts (P less than or equal to 0.003) and with decreased visual acuity (P less than 0.001). Additional analyses showed that contrast and glare sensitivity were similar in eyes with no cataracts and early cataracts. CONCLUSION These results suggest that the Pelli-Robson Chart and the Vistech MCT 8000 are good techniques for evaluating visual function in moderate to advanced cataracts. However, for early cataracts, other techniques need to be explored to assess visual function loss.

Efficiency robust tests of independence in contingency tables with ordered classifications

Ordered categorical data occur frequently in biomedical research. The linear by linear association test for ordered R x C tables permits the investigator to specify row and column scores for analysis. When an investigator believes that there may be more than one set of reasonable scores or when more than one investigator proposes scores, we need a method to decide upon a single procedure to use. We show how to use efficiency robustness principles to combine tests from two or more sets of scores into one robust test for analysis. This test minimizes the worst possible efficiency loss over all the sets of scores. We illustrate the methodology for the R x C case and, in detail, for the important special 2 x C case.