W. A J Van Heuven

Diabetic Retinopathy in Mexican Americans and Non-Hispanic Whites

Mexican Americans (MAs) have a threefold greater prevalence of non-insulin-dependent diabetes mellitus (NIDDM) than non-Hispanic Whites (NHWs). Because MA diabetic subjects have greater hyperglycemia and an earlier age of onset than NHW diabetic subjects, we postulated that diabetic MAs might also have more severe diabetic retinopathy. Stereoscopic retinal photographs of the seven standard fields of each eye were taken in 257 MAs and 56 NHWs with NIDDM. The photographs were read by the University of Wisconsin Fundus Photographic Reading Center and graded with standardized criteria. The MAs had a nonsignificantly increased risk of retinopathy relative to the NHWs [odds ratio (OR) = 1.71; 95% confidence interval (CI) = (0.93, 3.17)]. The risk of severe retinopathy (proliferative or preproliferative) relative to background or no retinopathy was significantly greater in MAs than in NHWs [OR = 2.37; 95% CI = (1.04, 5.39)]. After control by logistic regression for duration of disease, severity of hyperglycemia, age, and systolic blood pressure, MAs still had an increased risk of severe retinopathy relative to NHWs [OR = 3.18; 95% CI = (1.32, 7.66)]. Severe retinopathy was related to duration of disease, hyperglycemia, and insulin therapy in both ethnic groups. Previously diagnosed MA diabetic subjects also had an increased prevalence of any retinopathy [OR = 2.39; 95% CI = (1.63, 3.50)] and severe retinopathy [OR = 3.21 ; 95% CI = (2.24, 4.59)] relative to previously diagnosed White diabetic subjects (n = 896) from Wisconsin. The combination of an increased prevalence of NIDDM in MAs plus an increased severity of retinopathy in those MAs who have diabetes suggests that a major public health effort should be made to screen this ethnic group for retinopathy.

Screening for Diabetic Retinopathy: The wide-angle retinal camera

OBJECTIVE— To define the test characteristics of four methods of screening for diabetic retinopathy. RESEARCH DESIGN AND METHODS— Four screening methods (an exam by an ophthalmologist through dilated pupils using direct and indirect ophthalmoscopy, an exam by a physicians assistant through dilated pupils using direct ophthalmoscopy, a single 45° retinal photograph without pharmacological dilation, and a set of three dilated 45° retinal photographs) were compared with a reference standard of stereoscopic 30° retinal photographs of seven standard fields read by a central reading center. Sensitivity, specificity, and positive and negative likelihood ratios were calculated after dichotomizing the retinopathy levels into none and mild nonproliferative versus moderate to severe nonproliferative and proliferative. Two sites were used. All patients with diabetes in a VA hospital outpatient clinic between June 1988 and May 1989 were asked to participate. Patients with diabetes identified from a laboratory list of elevated serum glucose values were recruited from a DOD medical center. RESULTS— The subjects (352) had complete exams excluding the exam by the physicians assistant that was added later. The sensitivities, specificities, and positive and negative likelihood ratios are as follows: ophthalmologist 0.33, 0.99, 72, 0.67; photographs without pharmacological dilation 0.61, 0.85, 4.1, 0.46; dilated photographs 0.81, 0.97, 24, 0.19; and physicians assistant 0.14, 0.99, 12, 0.87. CONCLUSIONS— Fundus photographs taken by the 45° camera through pharmacologically dilated pupils and read by trained readers perform as well as ophthalmologists for detecting diabetic retinopathy. Physician extenders can effectively perform the photography with minimal training but would require more training to perform adequate eye exams. In this older population, many patients did not obtain adequate nonpharmacological dilation for use of the 45° camera.

Effect of socioeconomic status on hyperglycemia and retinopathy levels in Mexican Americans with NIDDM

Mexican Americans have a threefold greater prevalence of non-insulin-dependent diabetes mellitus (NIDDM) than non-Hispanic Whites. Moreover, Mexican-American diabetic people have more severe hyperglycemia and diabetic retinopathy than non-Hispanic White diabetic people. Mexican Americans are predominantly of low socioeconomic status (SES), and low-SES Mexican Americans have a higher prevalence of NIDDM than higher-SES Mexican Americans. Therefore, we hypothesized that among diabetic people, low SES would be associated with more severe hyperglycemia and retinopathy. Three hundred forty-three Mexican Americans and 79 non-Hispanic Whites with NIDDM were identified from the San Antonio Heart Study, a population-based study of diabetes and cardiovascular disease. Hyperglycemia was assessed as the sum of the fasting, 1-h, and 2-h plasma glucose concentrations during a standard oral glucose tolerance test. Retinopathy was assessed by 7 standard stereoretinal photographs. SES was assessed with three indicators: Duncans socioeconomic index, education, and income. Contrary to expectations, low SES was not associated with greater levels of hyperglycemia or grades of retinopathy.

Is there an ethnic difference in the effect of risk factors for diabetic retinopathy

Mexican Americans have an increased prevalence and incidence of non-insulin-dependent diabetes mellitus (NIDDM). In addition, Mexican American diabetic subjects have an increased prevalence of retinopathy relative to Caucasian diabetic subjects. In Mexican American diabetic subjects, established risk factors may have a stronger effect on diabetic retinopathy, compared to Caucasian diabetic subjects. In this report, we compare the effect of established risk factors (age at examination, gender, age at diagnosis of diabetes, duration of diabetes, glycemia, type of therapy, systolic and diastolic blood pressure, and hypertension prevalence) between Caucasian diabetic subjects (n = 478), a low-risk population for NIDDM (Wisconsin Epidemiologic Study of Diabetic Retinopathy), and Mexican American diabetic subjects (n = 231), a high-risk population for NIDDM (San Antonio Heart Study). Retinopathy was classified into two categories (any or none) as assessed by seven standard stereoscopic retinal photographs read at the University of Wisconsin Reading Center. Mexican American diabetic subjects in Texas had an increased prevalence of any retinopathy (odds ratio = 1.71, 95% confidence interval: 1.25, 2.34), compared to Caucasian diabetic subjects in Wisconsin. Longer duration of diabetes, more severe glycemia, earlier age at diagnosis, and insulin therapy were associated with diabetic retinopathy in both Mexican Americans and Caucasians. Socioeconomic status was not associated with prevalence of retinopathy. Moreover, the effect of risk factors for retinopathy was similar in both ethnic groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Echographic Characteristics of Benign Orbital Schwannomas (Neurilemomas)

We examined two patients with orbital schwannomas (neurilemomas). The echographic findings, including a sharply outlined capsule, a well-defined central cystic space within the tumor with very low internal reflectivity surrounded by smaller cysts with variable reflectivity, slight or no compressibility, and blood flow, should help to differentiate these benign tumors from other orbital lesions. Histologic examination showed a combination of Antoni type A (dense and cellular) and Antoni type B (loose, edematous, or necrotic) patterns.

Entoptic foveal avascular zone measurement and diabetic retinopathy.

BACKGROUND Entoptic visualization of the foveal avascular zone (FAZ) provides a noninvasive method for measurement of the FAZ. To determine if repeatability of measurement with this technique is good enough to monitor changes in diabetic retinopathy, we quantify (1) the repeatability of entoptic FAZ measurement in healthy subjects and (2) the relationship between measured FAZ diameter and the severity of retinopathy. METHODS (1) To determine FAZ measurement repeatability, 10 healthy adults entoptically measured their FAZ diameters in 11 separate testing sessions. (2) In a separate experiment, 53 patients with varying levels of diabetic retinopathy and 21 control subjects used a vascular entoptoscope to measure their FAZ diameters. RESULTS The disease-related increase in FAZ diameter is large (approximately 400 microm) compared to the repeatability of the entoptic measurement within a subject (SD approximately 35 microm). CONCLUSION Entoptic measurements have the repeatability necessary to reliably monitor increases in FAZ diameter of the magnitude of those induced by diabetes.

Rod-cone interactions in the ERG of a patient with Bardet-Biedl syndrome

During routine ERG testing of a patient with Bardet-Biedl syndrome, we encountered an ERG anomaly not previously reported. A white flash which produced a response during light adaptation would produce no ERG when the retina was dark-adapted. Possible explanations for this phenomenon are discussed.

ROP surgery and ocular circulation

PurposeVisual results following vitreoretinal surgery for stages 4 and 5 retinopathy of prematurity are often disappointing, even when anatomic results are good. This poses the question whether the surgery or the post-operative care causes the optic atrophy. A hypothesis is proposed that ocular perfusion pressure (mean blood pressure minus intraocular pressure) during or after surgery may be too low to provide adequate ocular blood flow.MethodsThis report analyses the published results of retinopathy of prematurity surgery, the techniques used, as well as data about blood pressure and intraocular pressure in premature infants.ResultsMean blood pressure in conscious premature infants is low and labile; it falls further under anaesthesia. Pre-operative intraocular pressure in retinopathy of prematurity patients is unknown, but intraocular pressure during vitrectomy is elevated, and likely elevated postoperatively.ConclusionsConditions during and after vitreoretinal surgery for retinopathy of prematurity are conducive to low ocular perfusion pressure and consequent ischaemia of the retina and optic nerve, which can contribute to poor visual results. Improved monitoring and control of ocular perfusion pressure is warranted.

Echographic diagnosis of acute retinal necrosis

Two cases of acute retinal necrosis (ARN) and severe vitritis in immunologically compromised patients, one monocular and one binocular, were found to have similar echographic characteristics. The response to appropriate medication and vitreous and retinal biopsy confirmed the diagnoses. Subsequently, a third case in an immunologically competent patient was found to have identical echographic findings, suggesting a diagnosis of herpetic ARN, which permitted appropriate treatment to be given. The typical echographic picture consists of vitreous opacities, vitreous schisis and loculation (cyst-like), vitreo—retinal traction, retinal detachment, subretinal opacities and choroidal thickening.