Estimate and measure of the region of view and myopia resulting from vitreous gas.

PURPOSE: After vitreous gas injection, patients notice better acuity in downward gaze than in horizontal gaze. The authors evaluated the refractive error and the size of the region within which vision improves. METHODS: For the vitreous fluid-gas interface, the authors calculated the angle of total internal reflection and the expected myopic shift and then measured them in nine consecutive patients. The volume of gas, declination angle at which perception of small targets occurred, and preoperative and postoperative refractive error in downward gaze were measured. RESULTS: Total internal reflection occurs at 41.5 degrees declination. Patients perceived a region of improved acuity below 41 degrees (+/-5 degrees) declination. The difference between the calculated and clinically measured gas-induced myopia was less than 25% for five of nine patients. The largest measured induced myopia was -23.9 diopters (60% gas volume). In eight eyes, patients read 5-point type or smaller. CONCLUSIONS: Patients accurately perceive that their acuity improves in downward gaze; the boundary of this region corresponds with the angle of total internal reflection. Calculations predict that vitreous gas produces a myopic shift and aberration. These data support the notion that ocular positioning by patients with vitreous gas can be enhanced by instructing them to regard near targets in downward gaze.

Estrogenic and DNA-damaging activity of Red No. 3 in human breast cancer cells.

Exposure to pesticides, dyes, and pollutants that mimic the growth promoting effects of estrogen may cause breast cancer. The pesticide DDT and the food colorant Red No. 3 were found to increase the growth of HTB 133 but not estrogen receptor (ER) negative human breast cells (HTB 125) or rat liver epithelial cells (RLE). Red No. 3, beta-estradiol, and DDT increase ER site-specific DNA binding to the estrogen response element in HTB 133 cells and increase cyclin-dependent kinase 2 activity in MCF-7 breast cancer cells. Site-specific DNA binding by p53 in RLE, HTB 125, HTB 133, and MCF-7 cells was increased when they were treated with Red No. 3, which suggests that cellular DNA was damaged by this colorant. Red No. 3 increased binding of the ER from MCF-7 cells to the estrogen-responsive element. Consumption of Red No. 3, which has estrogenlike growth stimulatory properties and may be genotoxic, could be a significant risk factor in human breast carcinogenesis.

Clinical study of a large family with autosomal dominant progressive cone degeneration.

PURPOSE: Autosomal dominant cone degeneration is an uncommon disorder characterized by progressive photophobia, hemeralopia, decreased central vision, and dyschromatopsia. To better understand the variable expressivity of autosomal dominant cone degeneration, we studied a single, large family. METHODS: We performed comprehensive ophthalmic examinations, full-field electroretinography, foveal electroretinography, and color vision studies on 73 family members. RESULTS: Of the 73 family members, 34 were affected. Symptoms generally began in the first decade of life and slowly progressed into midlife. Ophthalmoscopic findings consisted primarily of macular granularity or central macular atrophy. The photopic full-field electroretinogram was important in establishing the diagnosis, although the results of the electroretinographic measurements varied across individuals. Either the foveal electroretinogram amplitudes were abnormally low or the foveal/parafoveal ratio was abnormal in all affected subjects. CONCLUSIONS: No single test or finding was completely sensitive or specific for accurate diagnosis of autosomal dominant cone degeneration. Especially in the more mildly affected subjects, a constellation of symptoms, findings, and test results were used to diagnose autosomal dominant cone degeneration accurately.

Mapping of autosomal dominant cone degeneration to chromosome 17p.

PURPOSE: We studied a single, large family with autosomal dominant cone degeneration in order to map the disease-causing gene. METHODS: Seventy-three individuals in this family were examined, and 34 were found to be affected. Blood samples from 34 affected and unaffected family members were obtained for DNA analysis and linkage mapping. Fifty-three genetic markers were analyzed in this family by using short tandem repeat markers. These markers were primarily in candidate genomic regions. RESULTS: Marker D17S796 generated a significantly positive LOD score of 4.21 (theta = .04; 10,000:1 odds in favor of linkage). Marker D17S513 gave a significant LOD score of 3.1 (theta = .096; 1,000:1 odds in favor of linkage). Other markers in the region generated suggestive findings, such as D17S786, with a LOD score of 2.7, and D17S945, with a LOD score of 2.41. CONCLUSIONS: Our results indicate that a genetic defect that causes autosomal dominant cone degeneration is located on chromosome 17p in the region of recoverin. Recoverin, a retinal expressed gene, is an appealing candidate for this disease.

Clinical features and pathogenesis of Alport retinopathy.

BACKGROUND: Alport syndrome refers to the clinical triad of hereditary nephritis, sensorineural deafness, and ocular abnormalities. Ultrastructural findings in the lens capsule and in the renal glomeruli have provided evidence that abnormal basement membranes are elaborated in affected tissues of patients with this disorder. Recently, the results of several linkage studies have allowed the genetic defect in Alport syndrome to be mapped to a locus that codes for a subtype of type IV collagen (alpha 5) known to be present in glomerular basement membranes. In spite of these advances, the nature of the retinal flecks in Alport syndrome and the visual consequences of the flecks remain controversial. METHODS: Detailed psychophysical and electrophysiologic testing was performed in a young man with Alport syndrome. The concurrence of an unusually extensive fleck retinopathy and unilateral pseudophakia afforded a unique opportunity to assess the effect of the flecks on retinal function. RESULTS: No sensory deficits were present in the eye with clear media. CONCLUSION: Macular flecks in Alport syndrome are not associated with demonstrable retinal dysfunction. The authors address questions about the nature and pathogenesis of the flecks in light of new clinical and genetic information.

Hemeralopia in an older adult.

An elderly male was referred for evaluation of hemeralopia when cataract extraction did not alleviate his symptom of difficulty seeing in bright illumination. Visual acuity was 20/40 OU. Funduscopic examination revealed marked arteriolar attenuation, disc pallor, and retinal pigment epithelial changes. Visual fields demonstrated relative paracentral scotomata. An ERG was consistent with widespread photoreceptor degeneration. A diagnosis of visual paraneoplastic syndrome was made and an extensive systemic evaluation revealed a squamous cell carcinoma of the lung. The presentation and evaluation of acquired photoreceptor dysfunction in adulthood is discussed.

Transmission electron microscopic study of a subretinal choroidal neovascular membrane due to age-related macular degeneration.

From a patient with age-related macular degeneration we studied ultrastructurally a disciform scar that was removed from an eye with a vitreous hemorrhage. In cross section, the scar was divided by a retinal pigment epithelial (RPE) cell layer. The choroidal side consisted of fibrovascular tissue with active neovascular buds and inflammatory cells, including macrophages attached to the RPE basement membrane. Apart from the RPE, no components of Bruch's membrane could be identified. The retinal side contained organizing hemorrhage and a collagenous matrix with fibroblastlike cells probably of RPE and choroidal origin. The anatomy and the clinical findings at surgery suggest that such scars lie on (rather than within) the inner collagenous layer of Bruch's membrane and contain two components divided by the original RPE layer. The choroidal side is fibrovascular, including active neovascularization, and the retinal side is fibrous and formed by metaplastic RPE cells and choroidal fibrovascular ingrowth.