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

Photoablation of ocular tissues is not restricted to the excimer laser. Alternative tools are erbium lasers. As there is maximum absorption in ocular tissue at about 3 microns, two types of erbium lasers are capable of photoablation. One is the Er:YAG laser working at a wavelength of 2.94 micron; the other is the Er:YSGG laser emitting light with a wavelength of 2.79 microns. Both lasers produce higher ablation rates than the excimer laser. In comparison to the excimer laser (thermal damage of less than 1 micron), there is more thermal damage in the remaining tissue (3 microns). The lower ablation rate of the Er:YSGG laser due to the greater distance of the wavelength from the absorption maximum can be compensated by a higher output energy and a higher repetition rate (25 Hz). Wound-healing studies in rabbit corneas show no significant differences between the excisions performed with the Er:YAG laser and 193 nm excimer laser.

Twenty-eight patients were studied who required treatment for hypercholesterolemia type IIa. Familial hypercholesterolemia was found in 53%. Sixty percent of all patients had arcus senilis. When familial and non-familial hypercholesterolemia were compared the incidence of arcus senilis was 80% and 38%, respectively. The gradation of the condition was minor (n = 9), moderate (n = 4), or pronounced (n = 4); all patients with a strong degree and 7 of 8 patients with either moderate or pronounced arcus senilis had familial hypercholesterolemia. The mean cholesterol level was 345 +/- 82 in patients with familial hypercholesterolemia and 353 +/- 120 mg/dl in patients with non-familial hypercholesterolemia. Although the correlation between the cholesterol level and the degree of arcus senilis was higher in patients with familial hypercholesterolemia than in those with non-familial hypercholesterolemia (r = 0.45 versus r = 0.17), neither had clinical relevance. There was no connection between the cholesterol level, refraction or visual acuity. The mean contrast sensitivity measured for five different spatial frequencies in all patients was normal. In comparison with patients without arcus senilis, the mean values in patients with severe arcus senilis showed lower contrast sensitivity for the higher spatial frequencies.

We examined 44 HIV-positive patients in different disease stages with electroretinogram (ERG), pattern-electroretinogram (PERG), and visually evoked cortical potentials (VECP). Sixty-eight of the 88 eyes examined had a normal fundus and full central vision. Twelve eyes showed cotton-wool ecudates and 8 eyes CMV retinitis. Fifty-four eyes with normal fundus were examined by ERG. Of these 28 (52%) showed marked reduction of the amplitude. In the PERG, 20 eyes out of 50 examined (40%) showed an amplitude reduction. In the VECP, 12 out of 65 eyes (19%) had a reduced amplitude. In the ERG, 7 of 11 eyes (64%) with cotton-wool exudates showed marked pathological findings, as opposed to 4 of 10 cases (40%) in the PERG and 3 of 12 (12%) in the VECP. Seventy-five percent of the eyes with CMV retinitis (6 of 8 cases) showed pathological findings in the ERG and VECP and 100% (all 7 cases examined) in the PERG. These electrophysiological findings suggest that there are diffuse disorders in the retina of HIV-positive patients. It is possible that these findings are based on direct infection of the retina with HIV, or that they represent a vascular disorder, subclinical infection or are related to side effects of the drugs used for the HIV infection.

Experimental autoimmune uveoretinitis (EAU) is a predominantly T-cell-mediated autoimmune inflammatory disease of the retina and uveal tract of the eye. Retinal S-antigen, a protein found in retinal photoreceptor cells, is a potent agent for the induction of EAU in susceptible species and strains. Elevated titers of antibody to S-antigen have been reported in patients with different forms of uveitis. Serum samples from 166 patients and 87 healthy blood donors were tested by immunoblotting against human retinal abstract for IgG, IgM and IgA antibodies to S-antigen. Compared to the controls the patient sera showed a higher incidence of S-specific antibodies (17.5% vs 9.2%). No specific correlation between the presence of any type of uveitis and anti-S antibodies has been found (anterior uveitis 15.1%, posterior 19.6%, panuveitis 18.9%). There was a higher incidence especially with IgG antibodies during active disease (19.7% vs 9.2% in controls). The results suggest that since EAU is T-cell mediated, antibodies in humans may be most important as indicators of autoimmunity rather than mediators of the inflammation. As these anti-S antibodies might be induced by disruption and nonspecific inflammation of the retina and uvea alone, an important and difficult question in patients is whether or not these secondary autoimmune response can contribute to the induction of uveitis.

Corneal wound healing was studied after photoablation with an excimer laser (193 nm, 43 pulses at 180 mJ/cm2 [symbol: see text] 11 microns ablation depth, optical zone 2.0 mm) and with an erbium-YAG laser (2.94 microns, 5 pulses at 2.5 J/cm2 [symbol: see text] 50 microns ablation depth, optical zone 1.6 mm). The corneas of marmosets (Callithrix jacchus) were prepared 5 and 10 days and 4 and 25 weeks after photoablation. The sections were investigated by conventional light microscopy or exposed to antibodies against collagen types I, III, IV, VII and laminin and stained by indirect immunofluorescence. Macroscopically, the time-course of wound healing was comparable to that seen, after laser keratomileusis for correction of myopia in humans (epithelium closure after 24-48 h, subepithelial haze: erbium-YAG less than or equal to excimer). Histologically the time-course of wound healing could be schematically divided into three phases: (1) epithelial hyperplasia, inhomogeneous new synthesis of collagen fibrils subepithelially; (2) reorganization of the epithelium, hyperplasia of keratocytes, incipient reorganization of the collagen fibrils, increase in subepithelial haze; (3) reorganization of the collagen fibrils, decrease in subepithelial haze. The distribution of collagen type VII during the corneal wound healing suggests that the subepithelial haze observed during the healing process after laser keratomileusis for correction of myopia is based on the anchoring fibrils of the basement membrane.

Uni- or bilateral dilatation of pupils that are not reactive to light and lack miosis in response to 1% pilocarpine may be caused by contact with plants containing alkaloids such as scopolamine and atropine. Other causes of a non-light-reactive dilated pupil, such as Adie's tonic pupil, third nerve palsy and lesion of the mesencephalic pretectal region, must be excluded before testing the iris sphincter reaction to 1% pilocarpine. Among the naturally growing flowers in Germany, deadly nightshade (Atropa belladonna), jimson weed (thornapple, Datura stramonium) and black henbane (Hyoscyamus niger) contain enough alkaloids to cause mydriasis by direct contact. However, in most cases an accidental mydriasis by plants in Germany is caused by Datura arborea taxa, e.g. Datura suaveolens, D. candida, D. aurea and D. sanguinea. They contain up to 0.6% dry weight scopolamine. These plants can grow very large and are often planted in tubs. They have to be cut back each year before the winter. This is typically how the eye is contaminated by parts of the plants, which can cause dilatation of the pupil mimicing a neuroophthalmological disorder.

While retinal vascular attenuation is a typical finding in retinitis pigmentosa (RP), studies on changes in choroidal vasculature have yielded contradictory results. In 44 patients with RP the relative pulse blood volumes were measured, and perfusion pressure videoangiography (PVA) was performed in 7 of them. Follow-up examinations were performed in 14 of the patients between 1.5 and 6 years later. The results show that the choroidal circulation is considerably reduced in RP patients; it was found to be further reduced at the follow-up examinations. PVA shows atrophy of the choroid capillary network. Characteristic changes occur not only in the retinal but also in the choroidal circulation, depending on the form, duration (stage) and prognosis of the disease.

The question as to whether silicone oil is toxic to the retina has not been resolved to this day. We have attempted to find evidence of retinal toxicity by studying the development of visual acuity in eyes operated on with silicone oil. We selected these eyes from a cohort of about 500 that had attached retina, no glaucoma and no keratopathy. The average visual acuity increased continuously over 2 years if all extraretinal factors influencing visual acuity are excluded. Although in eyes from which silicone oil had been removed visual function developed better than in those in which it remained indefinitely, this could not be attributed to a toxic effect of silicone oil, since the difference was apparent even while eyes in both cohorts where still filled with oil. The difference is more probably a result of patient selection. In individual cases in which silicone oil was not removed for up to 8 years the visual acuity remained stable. An analysis of the patients with loss of vision despite attached retinas yielded causes that were essentially specific to the underlying disease. We found no clinical evidence suggestive of a toxic effect of silicone oil.

An automatic visual acuity test examining visual acuity at 5 m distance is presented. An LCD screen with 400 x 640 pixel is used for graphic display. The Landolt rings are selected randomly. The test presented here complies well with the criteria of DIN 58220. Accuracy estimates for representation of the Landolt rings in raster graphics are discussed. With the method suggested, the testing of visual acuity, one of the most important tests in ophthalmological practice, is simplified and its reliability and results are improved. The method allows tests at short time intervals to trace the time dependency of visual acuity. Furthermore, the test may be delegated to support personnel.

Access to microbiological, pharmacokinetic and toxicological information is necessary for useful, controlled application of antibiotics in intraocular and periocular infections. It is important to know whether the antibiotic is effective against ophthalmologically relevant bacteria and if suprathreshold concentrations of the antibiotic can be achieved in the contaminated tissue. In the study presented we investigated the usefulness of cefmenoxime in cases of dacryocystitis. Lacrimal sac tissue--and serum specimens were obtained from 15 patients who underwent dacryocystorhinostomy 0.5 to 13 h after intravenous injection of 25 mg cefmenoxime kg. The usual Toti procedure was performed in 7 patients, whereas the other 8 underwent endonasal surgery. Out of the 15 patients 12 suffered from recurrent dacryocystitis. Before application of the antibiotic a serum control sample was obtained in all patients. The highest cefmenoxime levels in the lacrimal sac (72 mg/kg) were measured 30 min after injection. Thirteen hours after the injection, the cefmenoxime levels were too low to be measured. The levels of cefmenoxime in the lacrimal sac tissue were compared with the minimal inhibitory concentrations for the frequent occurrence of bacteria in lacrimal sac infections.