Fortschritte der Ophthalmologie : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft最新文献

Spatial uncertainty was examined according to a procedure suggested by Bedell and Flom (1981) ("triangle procedure") and additionally with a line-division test designed by Kundt. A horizontal line of a length of about 20 degrees and a shorter one of 4.3 degrees was divided into two equal parts. Strabismic amblyopes mark the middle of such a line with less precision and greater uncertainty than visually normal subjects do. Visual acuity was measured by single optotypes (Landolt rings), as well as by line optotypes with spaces of 2.6 min of arc between each other (C-test). Surprisingly, there was little correlation between visual acuity--even line acuity--and localization tasks.

We have recently reported a reduction of pattern electroretinogram (p-ERG) in patients with HIV infection. Amplitudes were reduced in HIV-infected patients with microangiopathy, but also in some cases with normal fundus. These findings suggested the existence of diffuse defects in ganglionic cell activity in HIV-infected patients. We have now started a prospective follow-up study in order to pursue the development of (a) p-ERG amplitudes and (b) funduscopic changes and visual acuity in these patients. In patients with normal fundus or microangiopathy who did not develop cytomegalovirus (CMV) retinitis, no significant tendency for the p-ERG amplitudes to fall could be demonstrated during the observation period of 1-16 (mean: 7) months. With the appearance of retinitis, the p-ERG amplitude decayed. In some cases, a pathologic p-ERG was recorded before retinitis appeared: 3 of 12 patients with p-ERG amplitudes in the pathological range later developed CMV retinitis and only 1 of 21 patients with normal p-ERG later developed retinitis. In some patients with AIDS or related disorders, p-ERG may be a useful additional diagnostic tool.

A randomized placebo-controlled study was conducted in 40 patients with acute retinal vein occlusion, 19 of whom received iso-(Hct greater than or equal to 42%) or hypervolemic (Hct less than 42%) hemodilution over 10 days with daily infusion of 250 ml hydroxyethyl-starch (MW 200,000/0.5, 10% HAES-steril) in combination with pentoxifylline (oral: 1200 mg/day; i.v.: 300 mg/day; Trental). After this 10-day trial of hemodilution rheological therapy was continued with pentoxifylline (oral: 1200 mg/day; Trental). The control group of 21 patients received no hemodilution or rheological therapy. After 10 days 35 patients underwent laser coagulation. Clinical, hemodynamic and rheological data of all patients were recorded before therapy, after 10 days but before laser coagulation, and after 6 weeks. In the group treated with hydroxyethyl-starch in combination with pentoxifylline, 10 patients had an improvement of central vision by two or more lines after 6 weeks. In the control group only 4 patients showed central vision improved by two or more lines after 6 weeks. In the treated group the retinal circulation and rheological data were significantly improved after 10 days of hemodilution therapy.

Platelet-derived growth factor (PDGF) is one of numerous growth factors regulating development of the ocular lens and its component parts. Although little is known about its site of action on the cell and the mechanisms of this confirmed mitogenic action, a close connection has been assumed between the influence of PDGF on both the lens epithelium and intracellular calcium homeostasis. The present study therefore examined the influence of PDGF on the concentration of intracellular free calcium [( Ca2+]i) in primary cultivated bovine epithelial cells. A dose-dependent [Ca2+]i increase of up to 300% followed stimulation with PDGF (5-50 ng/ml) in a medium containing Ca2+. [Ca2+]i also rose significantly in Ca(2+)-free medium, indicating mobilization from intracellular storage.

There is considerable clinical variability in autosomal dominant retinitis pigmentosa (ADRP). The underlying biochemical defect had remained unknown until recently, so that it was not possible to determine the primary cause(s) of this phenotypic diversity. Recently, different point mutations and base pair deletions have been identified in the rhodopsin gene in a proportion of patients with ADRP, providing convincing evidence for allelic genetic heterogeneity in this disease. We screened a total of 65 patients with ADRP in Germany, Austria, and Switzerland for the presence of the point mutations described recently at codons 58 and 347 in patients in the USA. Our results show that the frequency of point mutations at codon 347 in the patients studied here is about 3%, a figure similar to that found in the USA. The frequency of the mutation at codon 58 seems to be generally low. The identification of patients with point mutations in the rhodopsin gene offers the possibility, for the first time, of studying the correlation between genotype and disease phenotype.

A three-dose, randomized, double-blind parallel, placebo-controlled ocular tolerancy study was undertaken in 24 healthy, normal volunteers with two formulations of 2% MK-507 (L-671 152), a novel water-soluble, topical carbonic anhydrase inhibitor. In this study MK-507 was administered to humans for the first time. Subjects received 3 sequential drops of the test drug in one randomly selected eye (at 13:00, 14:00, and 14:10 o'clock): ten received 2% MK-507 formulated with 0.5% hydroxyethylcellulose (HEC); ten, 2% MK-507 with no HEC; two, vehicle with HEC; and two, vehicle without HEC. Local tolerance of 2% MK-507 was good with predominantly mild and transient local symptoms, somewhat fewer for the formulation without HEC. Significant lowering of intraocular pressure (IOP) by up to 7 mmHg was noted when comparing IOP 4 h and 5 h after the first dose with IOP 20 h and 19 h before the first dose in the treated eyes of subjects receiving MK-507. Slightly greater activity was noted when MK-507 was formulated with HEC.

Ethambutol leads to chronic, severe optic neuritis with sudden onset in approximately 5-14% of all patients. Therefore, the ability of visually (pattern) evoked potentials for the early diagnosis of ethambutol-induced optic neuritis was tested. During ethambutol therapy prolonged latency was documented in 5 of 15 cases (33%). One of these 5 cases showed a reversible decrease in visual acuity. Thus, during treatment with ethambutol visually (pattern) evoked potentials may reveal a surprisingly high percentage of subclinical optic neuritis. These patients need close supervision in order to facilitate early discontinuation of the drug when neuritis develops.

Intolerance to bright light is a nonspecific ophthalmological symptom, originating either in disturbances of the optic apparatus of the eye or caused by functional disturbances of the neuronal network of the retina. Disturbances in brightness and darkness adaptation can often cause considerable decrease in visual acuity, which is not evident in the standardized tests that measure photophobia in conjunction with visual function. If the test field is very bright and the patient has photophobia, the visual acuity is often reduced considerably. The relationship between visual acuity and luminance of the test field was determined in glare--sensitive patients using a relatively simple method and a large range of luminances (0.1-30,000 cd/m2). In contrast to previously used methods, visual acuity was determined in a range where neuronal mechanism can be expected to be responsible for adaptation to brightness. We found disturbances in the relationship between visual acuity and luminance in several diseases, and it was especially pronounced in cone dystrophies. Affections of the optic nerve and opacities of the optic media usually did not cause a marked decrease in visual acuity at high luminances. As a supplemental investigation to mesoptometry and nyctometry, the method described here primarily permits types of photophobia to be determined that are not caused by stray light. The dynamic nature of neuronal adaptation processes determined by this test has therefore considerable influence on visual acuity.

A promising method for noninvasive objective diagnosis and monitoring of the course of a therapy is spectrometric investigation of the human ocular fundus. Application of this method in clinical practice depends on the development of suitable procedures for deconvolution of the measured spectra. The availability of microcomputers permits the performance of complicated calculations directly at the measuring device. Based on the two-photon flux theory, the influence of absorption and scattering in anatomically determined layers of the fundus will be considered. For this reason, an iterative principle for radiation transport into the fundus is introduced, allowing derivation of a physical model for calculation of the spectral course of the reflected light. In the multisubstance analysis a measured spectrum is approximated by the model function. During this analysis the optical densities of photosensitive and nonphotosensitive pigments and the reflection at intermediate layers can be calculated. As an example of multisubstance analysis, the deconvolution of foveal reflection spectra of normals and type I diabetics is demonstrated. This method makes it possible to show that early diabetic alternations occur in the choroid.

Postoperative fibrinoid reactions are regarded as a localized form of endophthalmitis caused by microbial contamination of the capsular bag during intraocular lens implantation. The incidence of early fibrinoid reactions within the first 6 postoperative days following extracapsular cataract extraction was examined after intraocular administration of antibiotics vs placebo. In a double-blind randomized trial, 2 mg cefamandol or a placebo was administered in a 0.4-ml volume at the end of the operation. A group of 28 patients received the antibiotic (mean age 74.6 years; 15 f, 13 m), while 33 patients received the placebo (mean age 72,1 years; 21 f, 12 m). Fibrinoid reactions were observed in 8 out of 61 patients during the first 6 postoperative days. There was no significant difference between the antibiotic group and the placebo group (P = 0.31). We were unable to reduce the incidence of fibrinoid reactions although we had selected a broad-spectrum cephalosporin for antibiotic treatment. The results give rise to the suspicion that most of the early postoperative fibrinoid reactions we observed were not caused by contamination with bacteria of low pathogenicity.