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P Kroll

Publications and source records attributed to P Kroll.

At least 19 recordsLinked to original sources
PubMed2006

[Influence of vital dyes on the function of the outer blood-retinal barrier in vitro].

BACKGROUND: The use of vital dyes in "chromovitrectomy" allows the easier removal of less recognizable structures like epiretinal membranes (EM) or the inner limiting membrane (ILM). In recent years numerous studies demonstrated the use of indocyanine green (ICG), trypan blue (TB) and patent blue (PB) for this indication. Reports of the possible risk of these dyes, i. e. especially ICG, in respect of reduced visual acuity results, possible visual field defects or alterations of the retinal pigment epithelium (RPE) resulted in limitations in their application. MATERIAL AND METHODS: Human RPE cells and choroidal endothelial cells were cultured in monolayers on semipermeable membranes representing an in vitro model of the outer blood-retinal barrier. By measurement of the transepithelial electrical resistance (TER) the stable barrier function was determined. Two different models representing an air-filled and a fluid-filled eye were tested on the one hand by addition of the dye to the culture medium and, on the other, by direct application on the cell monolayer. In these two models ICG (5 mg/ml, 0.5 mg/ml, 0.125 mg/ml), TB (1.5 mg/ml, 0.15 mg/ml) and PB (2.4 mg/ml, 0.24 mg/ml) were applied for three minutes and the influence on the barrier function was determined. RPE cell growth was also tested in these two models after the application of ICG, TB and PB. Finally, monolayers of RPE cells were evaluated by transmission electron microscopy (TEM). RESULTS: After application of TB, PB and the lowest concentration of ICG of 0.125 mg/ml, the TER remained stable in both models. In contrast, ICG in a concentration of 5 mg/ml and 0.5 mg/ml caused a significant TER decrease in the model of the air-filled eye, whereas no influence on the function of the outer blood-retinal barrier was noted in the model of the fluid-filled eye. RPE cell growth rates were not influenced by the addition of the vital dyes, with the exception of ICG in a concentration of 5 mg/ml in the model of the air-filled eye, resulting in a temporary reduction of the cell count. In good correspondence to these results also in TEM intercellular blisters were noted after application of 5 mg/mL ICG for 3 minutes in the model of the air-filled eye. However, damage to the RPE cells themselves was not obvious. No pathological changes in the TEM were noted after application of TB and PB. CONCLUSIONS: The use of PB and TB at the posterior eye segment seems to be safe concerning damage to the PRE and its barrier function. In contrast, ICG in higher concentrations and with longer application times may cause a toxic effect on RPE morphology and function.

Blood-Retinal Barrier↗
PubMed2005

[Autologous serum versus hyaluronic acid eye drops for the treatment of corneal erosions after vitrectomy in diabetic patients. A prospective randomized study].

PURPOSE: The purpose of this study was to evaluate whether treatment with autologous serum exhibits better epitheliotropic properties than hyaluronic acid in patients with reduced wound healing (diabetics). PATIENTS AND METHOD: This prospective randomized study included all diabetic patients undergoing pars plana vitrectomy with abrasion of the corneal epithelium. In addition to the usual topical therapy one group was treated with hourly application of autologous serum, the other group with hyaluronic acid drops. We evaluated the time needed for closure of the corneal epithelium as well as other parameters such as patient's age, sex, duration of surgery, history of diabetes, and the current HbA1C. RESULTS: There were 23 patients enrolled in the study. The epithelium healed a mean of 2 days earlier in the autologous serum group. Based on the statistically significant difference in favor of autologous serum, the study was terminated after treatment of 23 patients. CONCLUSIONS: Autologous serum eye drops lead to earlier closure of the corneal epithelium after intraoperative abrasion in diabetic patients when compared with artificial tears.

Cornea↗
PubMed2005

[Subjective decrease of visual acuity after photodynamic therapy: documentation by optical coherence tomography and its correlation with visual acuity].

CASE REPORT: A 68-year-old patient complained of decreased visual acuity (VA) two days after photodynamic therapy (PDT) had been performed. VA decreased from the pre-operative value of 0.4 to 0.1 on the second postoperative day. With additional + 1.75 diopters, VA was 0.32. Optical coherence tomography (OCT) disclosed a subneuroretinal fluid accumulation causing a serous retinal detachment 600 microm in height. One week postoperatively, neither decreased vision nor retinal elevation were noted. DISCUSSION: The temporary subjective decreased VA could be predominantly reduced by adequate refraction. OCT and VA measurements excluded ischemia of the neuroretina or the choroid as a causative factor.

Aged↗
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↗