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Biomedical subjects

P Kroll

Publications and source records attributed to P Kroll.

At least 19 recordsLinked to original sources
PubMed2002

[Ocular blood flow in patients with asymmetric glaucoma].

BACKGROUND: Hemodynamic factors are gaining increasing importance in the pathogenesis of glaucoma. This study was designed to investigate ocular blood flow in patients with asymmetric glaucoma. METHODS: The more affected and the contra-lateral eyes of 15 glaucoma patients with asymmetric scotomas (difference in mean deviation >/=8 dB) despite equal IOP were compared with reference to IOP, optic nerve head excavation, mean deviation in scotomas and ocular blood flow (OBF). Exclusion criteria were defined as follows: operated eyes, secondary glaucomas, differences in IOP and in antiglaucoma therapy, differences in visual acuity >2 steps and other ophthalmological diseases. For statistical analysis the Wilcoxon test for paired samples was used. RESULTS: A comparison of IOP's of the more affected eyes with the contralateral eyes showed no differences. Vertical and horizontal excavation differed significantly ( p=0.027 and p=0.01, respectively) and also the mean deviation in scotomas showed a statistically significant difference ( p=0.001). The pulse amplitude and the pulse volume showed only a slight tendency, but the pulsatile ocular blood flow was significantly lower in the more affected eyes ( p=0.047). CONCLUSION: The lower pulsatile ocular blood flow in the more affected eye in patients with asymmetric glaucoma could be the lateralizing factor in these patients, and suggests an influence of hemodynamic factors in the pathogenesis of glaucoma.

Aged↗
PubMed2002

[Follow-up of proliferation of juxtapapillary retinal pigment epithelium].

PURPOSE: Bengin proliferation of the juxtapapillary retinal pigment epithelium is a rare but important tumor because it may be mistaken for a malignant lesion such as choroidal melanoma. CASE REPORT: A 9-year-old male patient consulted our clinic first in 1991 because of a reduction in visual acuity due to a tumor of the optic nerve head in the left eye. Visual acuity was 1.0 in the right eye and 0.2 in the left eye. Slit lamp examination and intraocular pressure were regular in both eyes. Kinetic perimetry showed a enlarged blind spot besides regular isopters. Funduscopy revealed a pigmented, ill-defined prominence of the optic nerve head with a mossy surface. In annual examinations were found a slowly progredient reduction in visual acuity up to 0.04 durning the last visit in January 2000 as well as a enlargement of the blind spot due to an increasing prominence and pigmentation of the optic nerve head. Because of the clincal aspect, the slowly progressive course, the enlargement of the blind spot with deterioration of vision and especially the florescein angiography, which revealed peripapillary capillary alterations with leakage, we diagnosed a proliferation of the juxtapapillary retinal pigment epithelium. CONCLUSION: The proliferation of the juxtapapillary retinal pigment epithelium can be differentiated from other pigmented tumors of the optic nerve head by its typical clinical aspect and course and especially by using flourescein angiography.

Capillary Leak Syndrome↗
PubMed2001

[Population-based study of diabetic retinopathy in Wolfsburg].

INTRODUCTION: Since November 1997 the complete documentation of an ophthalmological examination of diabetics has been annually subsidized by the Volkswagen Corporation Health Maintenance Organization (VW-HMO). METHODS: The results of an annual ophthalmological examination were recorded in a standardised history sheet developed by the Initiative Group for Early Detection of Diabetic Eye Diseases. These data included visual acuity, intraocular pressure, lens status and a description of fundus abnormalities. RESULTS: Within 26 months ophthalmological examinations of 2,801 patients were completed which represented 4.5% of all VW-HMO insured patients. On average, patients suffered from diabetes for 9.6 years (SD +/- 8.3), artificial intraocular lenses were present in 357 eyes (6.4%) and 1,216 eyes (12.0%) were diagnosed with cataract or posterior capsule opacification impairing visual acuity. Out of 263 patients younger than 40 years old, 18.8% had a mild or moderate and 3.3% a severe non-proliferative diabetic retinopathy (NPDR). A proliferative diabetic retinopathy (PDR) was found in 2.2% of the younger patients. Of 2,228 patients aged 40 years and older, 11.9% had a mild or moderate and 2.6% a severe NPDR. In 0.9% of this group PDR was diagnosed. CONCLUSIONS: An annual ophthalmological screening based on a survey sheet of the Initiative Group was successfully introduced. For the first time a population-based evaluation on the prevalence of diabetic retinopathy was carried out for inhabitants of a German city. The prevalence of PDR was found to be lower than previously published in comparable studied.

Adolescent↗
PubMed2001

[Histopathology of 8 corneal buttons after penetrating keratoplasty in silicone oil-associated keratopathy].

BACKGROUND: In the literature there is only a limited number of morphological reports on clinically diagnosed silicone oil associated keratopathy describing different histological changes. The purpose of the present study was to evaluate the most common histopathological features of this disorder. MATERIAL AND METHODS: We reviewed the registry of the ophthalmopathological laboratory at the University of Marburg with respect to the following histopathological diagnoses: "bullous keratopathy", "endothelial-epithelial corneal decompensation", "band keratopathy" and "endothelial degeneration". These specimens were cross-checked with appropriate medical records. Eight specimens with a clinical diagnosis of silicone oil induced keratopathy were identified. All specimens were examined by light microscopy. RESULTS: Histologically, a long-standing bullous keratopathy was seen in 5 out of 8 specimens. A descemetocele was present in two other corneas. One case displayed band keratopathy. A posterior collagenous layer (PCL) between Descemet's membrane and the endothelium was identified in 7 out of 8 specimens examined. This layer was of a fibrillar type in 2 corneal buttons and of a fibrocellular type in all remaining specimens with PCL. PCL was associated with endothelial cell loss and degeneration. The endothelial cell density varied between 0 and 5 cells per high power field. CONCLUSION: Posterior collagenous layer associated with degenerating endothelium appears to be the most frequent histopathological feature in silicone oil induced keratopathy. The variety of PCL in this condition makes a firm histopathological diagnosis of "Silicone oil induced keratopathy" rather difficult.

Adolescent↗
PubMed2000

Induction of posterior vitreous detachment in rabbits by intravitreal injection of tissue plasminogen activator following cryopexy.

The purpose of this study was to generate intravitreal plasmin after intravitreal injection of tissue plasminogen activator (TPA) and cryopexy, and to assess its proteolytic effect on the vitreoretinal border region.Twenty-four hr after a mild cryopexy, 25 microg recombinant tissue plasminogen activator (TPA) was injected into the vitreous cavity, the fellow eye received an intravitreal injection of the same volume of buffered salt solution. Light, scanning and transmission electron microscopy was performed in 24 eyes that underwent vitrectomy 1 week later. Plasmin was measured prior and 2 hr after intravitreal TPA injection (4 eyes). Hyaluronic acid (8 eyes) and vitronectin (4 eyes) were measured 1 week after TPA- or BSS-injection and compared to untreated controls. In all eyes treated with TPA, histopathologic examination by scanning and transmission electron microscopy demonstrated a complete detachment of the vitreous from the surface of the retina as well as from the posterior surface of the lens. After BSS-injection, vitreous cortex attachment to the retina was demonstrated in all eyes. Two hr after TPA-injection, plasmin increased to 9.75 mU ml(-1)(s.d.+/-2.3). Neither a decrease of hyaluronic acid nor an increase of transglutaminase, that might alter the vitreous structure leading to a collapse of the vitreous, were detected in treated eyes. There was no increase of vitronectin indicating proliferative activity.A temporary breakdown of the blood-retinal barrier by cryopexy combined with intravitreal injection of TPA is a sufficient technique to induce a posterior vitreous detachment enzymatically. The method may be useful prior to mechanical vitrectomy.

Animals↗
PubMed2000

[Maculopathy in Curschmann-Steinert myotonic dystrophy].

BACKGROUND: Maculopathy occurring in young patients is a challenge in differential diagnosis. Besides hereditary macular dystrophies and acquired macular degenerations, rare systemic disorders should be considered. CASE REPORT: A 36 year old female patient complained about a gradually decrease of visual acuity in both eyes and an increasing exotropia of her right eye. Visual acuity was 0.7, the orthoptical status revealed an intermittent exophoria with exclusion of the right eye. Slit lamp examination showed punctate and cristalline lens opacities. In fundus examination and fluorescein angiography clumpy pigment epithelium hypertrophies and atrophies with a reticular character could be observed. Color vision and perimetry were normal; dark visual acuity was reduced. Because of remarkable deformations of jaw and teeth, a high hairline and an uncertain step we arranged a neurological consultation. Clinical observation together with myotonic activities in electromyography and diffuse lesions in the cerebral medular corpus shown in MRT led to the diagnosis of myotonic dystrophy (Curschmann Steinert syndrome). CONCLUSION: Besides hereditary macular dystrophies and acquired macular degenerations the differential diagnosis of maculopathies in young patients also includes systemic disorders. Myotonic dystrophy (Curschmann Steinert syndrome) should be taken into account as a rare cause of a juvenile maculopathy.

Adult↗
PubMed2000

[Vitreoretinal surgery in complicated retinal detachment in children and adolescents].

BACKGROUND: The purpose of this study was to evaluate anatomical and functional results of vitreoretinal silicone oil surgery for complicated retinal detachments due to trauma and myopia in children and juveniles. METHODS: We retrospectively reviewed the records of children and juveniles up to 17 years of age who had undergone vitreoretinal surgery with silicone oil instillation for the above causes between 1990 and 1997. A total of 30 eyes of 29 patients were operated on, 24 because of trauma and the remaining 6 because of retinal detachment in high myopia. There was a mean postoperative follow-up period of 1.7 years. Silicone oil could be removed from 18 of the 30 eyes after a mean of 4.7 months. The median number of vitrectomies performed per eye was two (range one to five). RESULTS: In 21 of 30 eyes (70%) the retina could be reattached after one or more surgeries. Silicone oil was removed from 16 of these 21 eyes (53%) which was defined as anatomical success. Visual acuity increased (14 eyes, 48.3%) or remained unchanged (9 eyes, 31%) in 23 of 29 eyes (79.3%). Visual acuity decreased in 6 of 29 eyes (20.7%) despite surgery. Two eyes (6.7%) had to be enucleated due to bulbar phthisis. Seventeen eyes reached a postoperative visual acuity of at least counting fingers. In one child functional tests could not be performed due to young age. CONCLUSION: Vitreoretinal surgery with silicone oil endotamponade has become a standard procedure in treating complicated retinal pathologies in children and juveniles. In very young patients it is thought that silicone oil instillation has advantages over gas endotamponade since it is very difficult for children to keep the proper face-down positioning after the procedure. The retinal reattachment rate is encouraging. In the majority of cases visual acuity greater than or equal to counting fingers and thus orienting vision was reached postoperatively. In few cases even reading vision was regained.

Adolescent↗
PubMed2000

[Air endotamponade in 52 vitrectomies due to proliferative diabetic retinopathy--retrospective comparison with 40 vitrectomies without endotamponade].

BACKGROUND: In patients with proliferative diabetic retinopathy rebleeding after pars plana vitrectomy is one of the most common complications. We tried to reduce the rate of that complication by using an air endotamponade. PATIENTS AND METHODS: The following study is a retrospective comparison of 2 patient groups both after pars plana vitrectomy due to proliferative diabetic retinopathy. Group 1 was managed with air as endotamponade (n = 52, mean age 61.2 years), group 2 without any endotamponade (n = 40, mean age 59.4 years). Classification of the proliferative diabetic retinopathy as described by Kroll et al. [5] in both groups: 23 and 29 patients with stage A resp., 24 and 10 patients with stage B resp., 5 and 1 patient with stage C respectively. RESULTS: 77% of group 1 patients had an increase os vision by mean of 4.8 vision steps, in 70% of the group 2 patients vision increased by mean of 7.2 vision steps. Complications in both groups as follows: Rebleeding within 14 days 15% vs. 33%, development of secondary glaucoma in 9.6% and 17.5% resp., revitrectomy within 14 days were necessary in 3.8% resp. 2.5% of the patients, later revitrectomy in 13.5% vs. 42.5% of all patients. SUMMARY: Air endotamponade turned out to be appropriate to reduce the rate of postoperative vitreous rebleeding after pars plana vitrectomy due to proliferative diabetic retinopathy. We found no increase of secondary glaucoma or cataract.

Adult↗
PubMed2000

Quantitative effect of intravitreally injected tissue plasminogen activator and gas on subretinal hemorrhage.

PURPOSE: To quantify the effect of intravitreally injected tissue plasminogen activator (TPA) and an expanding gas on freshly formed subretinal hemorrhage (SRH). PATIENTS AND METHODS: Thirteen patients with acute (1 week or less) SRH due to age-related macular degeneration (ARMD) were treated with an intravitreal injection of 50 microg TPA, and 24 hours later, with an expanding gas. Fundus photographs taken before and 24 hours after each injection were digitized and calibrated. Area, geometric center, and shift of the SRH were measured at each time point using NIH image analysis software. Elevation of the SRH was assessed by echography. RESULTS: Compared to the preoperative size, SRH enlarged significantly 24 hours after TPA injection (P < 0.001). A significant shift of the geometric center toward the inferior retinal periphery out of the macula was found after gas injection (P < 0.001). Significant horizontal displacement of the SRH was not noted after TPA or gas injection. More elevated subretinal blood clots showed a larger increase in size after TPA injection than flat clots (P < 0.05). CONCLUSION: Enlargement of SRH in a gravity-dependent manner indicates subretinal liquefaction of the clot after TPA treatment. An intravitreal injection of gas 24 hours later can significantly displace the SRH inferiorly.

Acute Disease↗
PubMed2000

Pigment epithelium defects after submacular surgery for choroidal neovascularization: first results.

It was the aim of this study to compare postoperative pigment epithelium defects after submacular surgery for well-defined choroidal neovascularization (CNV) with preoperative fluorescein angiogram (FAG), indocyanine green angiogram (ICG), and intraoperative findings of the excised neovacularization. Surgical removal of the CNV was videotaped. By means of a gauge the absolute size of an anatomic structure was determined which was visible on video, FAG, and ICG as well. Postoperatively another FAG was performed to further examine the funduscopically visible pigment epithelium defect. By comparison with the above-mentioned anatomic structure it was thus possible to determine the exact size of CNV and pigment epithelium defect. The extent of the pigment epithelium defect as determined on postoperative FAG after submacular surgery surpasses the size of CNV as measured in FAG, ICG, and anatomical preparation.

Adult↗