Biomedical subjects

M M Gellrich

Publications and source records attributed to M M Gellrich.

7 recordsLinked to original sources

PubMed1998

Retinal ganglion cell layer and visual function in a patient with optic disc drusen.

BACKGROUND: To correlate the retinal ganglion cell pattern to visual acuity and visual field data in a patient with bilateral optic disc drusen, a quantitative clinicopathological study was carried out. METHODS: Both retinae of a patient with optic drusen were whole-mounted. Retinal ganglion cell counts were made using a sampling scheme covering the whole retina and compared to the findings in 10 normal retinae. Relative ganglion cell reduction in the drusen retinae was correlated to clinical data. RESULTS: The total retinal ganglion cell count was reduced from 1244858+/-98736 in normal retinae to 305319 on the right and 527571 on the left eye with optic disc drusen. Large ganglion cells had a better chance of survival. Parafoveal ganglion cell loss was 57% for the right and 36% for the left eye, while visual acuity was 0.8 and 1.0 respectively. The mean light sensitivity loss increased from the centre (6.2 dB) to paracentral (9.9 dB), mid-peripheral (13.7 dB) and outer peripheral (15.0 dB) retina, while ganglion cell losses were smallest in outer peripheral retina (21.9%), followed by central (53.0%), mid-peripheral (70.9%) and paracentral retina (87.7%). CONCLUSION: These data validate Frisén's theory on central retinal resolution and provide the structural basis for the clinical rule that low visual acuity should not be attributed to disc drusen. Automated light sense perimetry gives an inadequate picture of retinal damage caused by optic disc drusen.

Adolescent↗

PubMed1997

[Clinical and experimental study of traumatic optic nerve damage].

BACKGROUND: Traumatic optic nerve lesions (TONL) range from temporary affection of vision to avulsion of the optic nerve; often they are associated with more complex injuries. Usually Tonl are not regarded as an emergency. Up to now, we lack knowledge on the dependency of strength and duration of optic nerve lesions and the point of no return for afferent disorders of the visual pathway. MATERIALS AND METHODS: We performed a prospective study on 50 patients with severe midface and skullbase fractures in order to find characteristic ophthalmological, computer tomographic und electrophysiological findings as indicators of TONL, independent of patient cooperation. We used an animal model (Wistar rats; n = 117) to study calibrated optic nerve lesions and the resulting neurodegeneration in the retinal ganglion cell (RGC) layer quantitatively. RESULTS: The electrophysiological investigation of the visual system (flash VEP/ERG) proved to be highly specific (0.97) and sensitive (1.0) for detecting TONL (n = 18). In the rat model, we could demonstrate a linear relationship between total neuron number reduction and strength and duration of calibrated optic nerve lesion. CONCLUSIONS: Experimental results indicate that optic nerve decompression is useful only within the first hours after TONL to reduce secondary optic nerve lesion. Indication for optic nerve decompression requires early detection of TONL, which is made possible by the combination of flash VEP/ERG.

Animals↗

PubMed1996

Quantitative relations in the retinal ganglion cell layer of the rat: neurons, glia and capillaries before and after optic nerve section.

BACKGROUND: To study normal quantitative cellular relations and the effect of optic nerve section on neurons, glia and capillaries, morphometry was carried out on 24 whole-mount retinae of 12 rats. METHODS: In the left eye the optic nerve had been sectioned 30 days before death; the right eyes served as controls. Using a cresyl violet stain, cells in the retinal ganglion cell layer were evaluated at three distances from the papilla (1.2, 2.4 and 3.6 mm). RESULTS: Gradients for density of neurons, glial cells and capillary grid were all within a small range (center: mid:periphery = 1.41-1.59: 1.29-1.33: 1.00). For all these distances we found a fairly constant ratio among the three histological parameters: 44.7-46.6 neurons and 2.3-2.6 glial cells were counted per capillary grid square (geometric model for the capillary meshwork). Thirty days after section of the optic nerve the capillary meshwork remained unaffected (96.2 grid squares/mm2 before nerve section vs 94.7 grid squares/mm2 after nerve section) while glial cells had more than doubled (238 vs 498 cells/mm2) and nearly half of all neurons had gone (4371 vs 2244 cells/mm2). Size characteristics of amacrine cells were similar for all three eccentricities, whereas peripheral retinal ganglion cells tended to be considerably larger than central ones. CONCLUSIONS: Cresyl violet stain can be used to study quantitative changes of neurons, glial cells and capillary grid in the retinal ganglion layer of a single whole-mount retina. There is a remarkable degree of proportionality between the density of these cells over the whole normal retina.

Animals↗

PubMed1996

Clinical utility of cytomegalovirus urine cultures for ophthalmic care in patients with HIV.

BACKGROUND: The utility of cytomegalovirus (CMV) urine cultures was checked in patients with HIV (a) to identify those at risk for CMV retinitis and (b) to guide clinical decisions on treatment and prophylaxis of CMV retinitis. METHODS: HIV infected patients were tested for CMVuria by shell vial cell cultures. The prevalence of CMVuria was related to CD4 count, HIV risk group, and time before and after diagnosis of CMV retinitis. RESULTS: A total of 639 shell vial cell cultures were obtained from 266 HIV infected ophthalmic patients. Only 4% of all patients with a CD4 count > 400 x 10(6)/l shed CMV in their urine compared with 42% with a CD4 count < or = 50 x 10(6)/l. Twenty three of 25 patients with CMV retinitis had a CD4 count < or = 50 x 10(6)/l. Among 130 patients with a CD4 count < or = 50 x 10(6)/l (a) those who were CMVuric had a nearly sevenfold risk (p < 0.0001) of developing CMV retinitis (35%) compared with those who did not shed CMV in their urine (5%), and (b) CMVuria and CMV retinitis were more frequent in homosexuals (58%/25%) than in intravenous drug users (23%/15%). More than 1 year before diagnosis of CMV retinitis 18% of patients were CMVuric compared with 83% of patients who were CMV culture positive in the last 3 months. CMVuria under virustatic maintenance therapy is associated with worsening of retinitis in two thirds of cases. CONCLUSION: Ophthalmic screening of patients with HIV should include those with a CD4 count < or = 50 x 10(6)/l and focus on the subgroup with additional CMVuria. Screening of other patients can be dropped without undue risk in order to spare AIDS patients unnecessary hospital visits. CMVuria as a single finding, however, does not justify antiviral prophylaxis of CMV retinitis.

AIDS-Related Opportunistic Infections↗

PubMed1996

Pattern, flicker, and flash electroretinography in human immunodeficiency virus infection: a longitudinal study.

To study electroretinographic (ERG) changes in the course of human immunodeficiency virus (HIV) disease, 42 eyes without retinitis were examined twice or more. During 9.6 months of mean observation time the visual acuity did not change. We found progressive functional impairment for the first, second, and third neurons of the visual pathway: the pattern-ERG amplitude (retinal ganglion-cell function) decreased by 11%, the b-wave amplitude (bipolars mediated by Müller cells) decreased by 13%, and the a-wave amplitude (dominated by rods) diminished by 21%. The flicker amplitude (dominated by cones) decreased by 20%. All of the latter four changes were significant (P < 0.02). Damage to the retina in HIV infection cannot solely be explained by visible changes in HIV retinopathy.

Adult↗

PubMed1994

Influence of fetal brain grafts on axotomized retinal ganglion cells.

The neurotrophic activity of fetal brain grafts next to the proximal stump of the transected optic nerve of adult rats was investigated. Axotomy (n = 25) reduced the original retinal ganglion cell population by 90% and the mean neuron size by one-third within 30 days. No increase in number or size of the surviving neurons could be found in any group receiving an embryonic brain graft (E16; spinal cord: n = 16, cerebral cortex: n = 16, tectum: n = 15, thalamus: n = 17) at the site of optic nerve transection, despite good survival of transplants. Although no positive effect on axotomized retinal ganglion cells could be found after transplantation of embryonic central nervous system structures, the same experimental model of the optic nerve seems to be valuable for further investigations of degeneration of traumatized retinal ganglion cells.

Animals↗

PubMedDate not supplied

[Indications for eye examination of HIV patients--screening parameters for cytomegalovirus retinitis].

BACKGROUND: To reduce the burden of frequent visits at the physician we have checked (I) for which ocular manifestations in HIV-infection screening of asymptomatic patients is worthwhile and (II) which parameters may indicate patients at risk for CMV-retinitis. PATIENTS AND METHODS: The clinical data of 215 HIV-infected patients were analyzed retrospectively. Only those ocular manifestations were considered suitable for screening that (a) endanger vision, (b) are treatable, (c) can be diagnosed sufficiently early and (d) are common. Furthermore (1) CDC-stage, (2) CD4+ count, (3) HIV-retinopathy, (4) CMV-uria and (5) CMV-antibodies were checked for their usefulness in indicating patients at risk for CMV-retinitis. RESULTS: Ophthalmological screening of asymptomatic HIV-patients should focus on cytomegalovirus (CMV)-retinitis because early diagnosis of this common blinding disease improves the visual outcome. 85 of 215 HIV-infected patients had a CD4+ count less than 50 cells/microliters 25% of these patients developed CMV-retinitis (21/85). The risk for CMV-retinitis rose to 38% (13/34) when the low CD4+ count was accompanied by CMV-uria. The proportion of patients with CMV-retinitis did not increase when HIV-retinopathy had been diagnosed earlier (12/48 = 25%). CMV-serology and CDC-classification were not helpful in screening for CMV-retinitis. CONCLUSIONS: We recommend the following ophthalmological screening scheme for HIV-patients without ocular symptoms: (1) patients with a CD4+ count < 100 cells/microliters should be checked every third month and (2) those with a CD4+ count < 50 cells/microliters and CMV-uria every sixth week.

AIDS-Related Opportunistic Infections↗