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G K Lang

Publications and source records attributed to G K Lang.

At least 19 recordsLinked to original sources
PubMed2003

Low content of the natural ocular anti-angiogenic agent pigment epithelium-derived factor (PEDF) in aqueous humor predicts progression of diabetic retinopathy.

AIMS/HYPOTHESIS: Retinopathy is the most common microvascular complication of diabetes. Our aim was to address the predictive value of pro-angiogenic and anti-angiogenic markers for progression of retinopathy. METHODS: Aqueous humor was collected at cataract surgery from 32 diabetic patients who had no or very mild retinopathy (ETDRS stage </=20) and 33 normoglycaemic control subjects. Content of pro-angiogenic vascular endothelial growth factor and angiogenic inhibitor pigment epithelium-derived factor were determined. ANGIOGENIC activity was quantified by measuring its effect on the migration of capillary endothelial cells. The predictive value of the initial level of these markers for progression of retinopathy was studied by following the probands for a maximum of 75 months. RESULTS: In the aqueous fluid content of vascular endothelial growth factor was increased in diabetic patients (mean values 492 versus 292 pg/ml; p=0.0052), and pigment epithelium-derived factor values were decreased (mean values 1740 versus 3680 ng/ml; p=0.0058) compared to control subjects. Of the diabetic patients ten progressed during follow-up (ETDRS stage >47B). This subgroup showed lower pigment epithelium-derived factor content when compared to non-progressors and control subjects. Migratory activity in samples of patients from the control group and in diabetic patients without progression was generally inhibitory due to pigment epithelium-derived factor. Inhibition was blocked by neutralizing antibodies to pigment epithelium-derived factor. In diabetic patients initial angiogenic activity was higher in those who later developed retinopathy (vs. controls p=0.00005; vs. no progressors p=0.0003). Both pigment epithelium-derived factor and migratory response predicted progression. CONCLUSION/INTERPRETATION: Pigment epithelium-derived factor is an important negative regulator of angiogenic activity of aqueous humor. Its content in the aqueous humor of diabetic patients strongly predicts who among them will develop progression of retinopathy.

Aged↗
PubMed2002

[Intracanalicular trabeculostomy with the Er:YAG laser].

PURPOSE: To develop a new ab externo technique for glaucoma trabecular surgery using the infrared Er:YAG laser radiation (2.9 micrometer) guided into Schlemm's canal by an optical fiber. MATERIAL AND METHODS: In order to create a drainage canal to the anterior chamber, a quartz fiber (core diameter: 100 micrometer) coupled to an Er:YAG laser was shielded by a metal canula (diameter: 280 micrometer) bent in conformance to the curvature of Schlemm's canal. A 45 degrees -mirror enabled the laser radiation to exit the canula perpendicular to the fiber axis. The complete surgery device was tested on agar medium and enucleated human eyes. RESULTS: Using the unshielded quartz fiber, eight pulses of 8 mJ (frequency: 7 Hz, pulse duration: 150 microseconds) were sufficient to perforate the trabecular meshwork of the human eye. Histology showed a rippled canal with 50 micrometer average diameter and a surrounding necrosis zone of 15-35 micrometer. The complete device could be easily inserted into Schlemm's canal similar to the classic trabeculostomy probe and a conical-shaped canal with a length of 2-3 mm could be created in agar medium within a few seconds. CONCLUSIONS: Initial experience in an experimental set-up show the ab externo creation of a draining canal between Schlemm's canal and the anterior chamber with only minimal irritation of the surrounding tissue. Further refinements of the laser parameters and the biomechanical set-up resulted in a new hand-held device with improved function. The Er:YAG laser intracanalicular trabeculostomy could become a new ab externo technique for minimal invasive therapy of open angle glaucoma.

Equipment Design↗
PubMed2002

[Endophthalmitis following cataract surgery].

BACKGROUND: Infectious endophthalmitis is a serious complication following cataract surgery, since it often induces a substantial reduction of visual acuity. PATIENTS AND METHODS: We retrospectively evaluated the clinical data of 53 patients with endophthalmitis following cataract surgery who were treated at the department of ophthalmology of the University Hospital in Ulm between 1995 and May 2001. Of these patients, 50 had been referred. Clinical presentation, infecting organism, treatment and visual outcome were analysed with a followup ranging from 2 weeks up to 42 months (median: 6 months). RESULTS: In 52 patients endophthalmitis was preceeded by cataract extraction and IOL implantation, in one case by secondary IOL implantation. Confirmed microbiologic growth was demonstrated from intraocular specimens in 26 out of 41 operated eyes (63%), the most frequent causative organisms were coagulase-negative Staphylococci (50%). All isolated bacteria were sensitive to a combination of the antibiotics vancomycin and amikacin or vancomycin and ceftazidime. 13 patients were treated with intravenous antibiotic therapy alone. In 46% of patients, who were initially treated with intraocular antibiotic injections alone, required further therapeutic intervention for recurrent infection. Only 7.7% of the patients who initially underwent intraocular antibiotic injections combined with IOL removal or pars plana vitrectomy with or without IOL removal, required further surgical intervention. Initial visual acuity was hand movements (median) only but improved during follow-up to 0.2 (median). CONCLUSIONS: In this series all tested bacteria were susceptible to the combination of vancomycin with either amikacin or ceftazidime. Aggressive initial treatment including IOL removal may be associated with a lower frequency of recurrent disease.

Amikacin↗
PubMed2002

[Objective determination of optical density of xanthophyll after supplementation of lutein].

BACKGROUND: It is thought that a high optical density of xanthophyll has a protective effect against the development of aggregated macular degeneration. The aim of this study was to investigate whether an increase of the optical density of xanthophyll in the macula after a supplementation of lutein can be proven by objective methods. Most methods applied for the determination of the macular pigment require the co-operation of the proband and the ability for foveal fixation. METHOD: Imaging spectrometry and the evaluation of laser scanner images taken at 488 nm will be presented. In contrast to psychophysical methods, both methods are independent of the patients ability for foveal fixation. RESULTS: Even by evaluation of laser scanner images taken as in fluorescence angiography but without inserting the blocking filter, the 2-dimensional distribution of xanthophyll can be determined. In 10 probands taking 6 mg lutein daily over 40 days, an increase of the optical density could be determined at least in some probands. The optical density reached a plateau 30 days after starting the supplementation of lutein. CONCLUSION: The assumed protective effect of xanthophyll against age-related macular degeneration can be influenced by supplementation of lutein under objective control.

Adult↗
PubMed2001

[Iris metastases in breast carcinoma].

BACKGROUND: Metastatic cancer of the iris is rare. We report a case of breast carcinoma which metastasized to the iris and a review of the literature. METHOD: A 60-year-old woman with a history of breast carcinoma presented with lesions of the iris 5 years after diagnosis and tumor excision. In addition to slit-lamp examination including gonioscopy, ultrasound biomicroscopy, positron-emission tomography and fluorescein angiography of the iris were used for diagnosis. Furthermore, the literature was searched using the medline database. RESULTS: The iris metastasis exhibited multiple whitish to pink nodules on the inferior half of the iris and infiltration of the chamber angle. The main tumor mass was prominent and highly vascularized. Best corrected visual acuity was 20/40 and the intraocular pressure was 7 mmHg. Ultrasound biomicroscopy showed lobular masses characterized by mid to low reflectivity and there was no distinct border to the surrounding tissue. Fluorescein angiography of the iris showed tumor vessels with dye leakage. The positron-emission tomography displayed metastatic lesions to the liver, lung, bones and lymph nodules in addition to the lesion of the iris. The review of the literature revealed that breast carcinoma leads to choroidal metastases in 5% of cases and iris metastases are even rarer. In twothirds of these cases the lesions form unilateral whitish to red clumps at the horizontal meridian and in the inferior quadrants of the iris. The preferred treatment is chemotherapy and/or radiation therapy. CONCLUSIONS: Breast carcinoma is rarely associated with iris metastasis. Positron-emission tomography is a sensitive diagnostic tool to identify metastatic lesions and is a useful method for planning therapeutic approaches. Radiation therapy, argon laser treatment and block excision are therapeutic options with an isolated metastasis of the iris.

Breast Neoplasms↗
PubMed2001

[Prospective randomized comparative study of frequency doubling perimetry vs standard automated perimetry in patients with glaucoma].

AIM: To compare frequency doubling perimetry (FDP) versus standard automated perimetry in glaucoma. To evaluate the reproducibility of both methods. PATIENTS AND METHODS: All the patients were tested (full threshold test) twice with both FDP (N-30) and Humphrey Field Analyzer II model 750 (HFA) (30-2 procedures) in random sequence, within one day. The parameters mean deviation (MD), pattern standard deviation (PSD) and measured thresholds per quadrant and center areas were evaluated for FDP/HFA comparison in 45 glaucoma patients. The same parameters were used for testing the reproducibility of FDP (n = 46) and HFA (N = 39). Additionally, the center and each quadrant area were checked for any deviation in the total deviation probability plots. For statistical analysis Kappa coefficients and Bland/Altman plots were used. RESULTS: An average MD (FDP vs HFA) of -7.3 +/- 5.8 dB vs -8.9 +/- 7.6 dB and PSD of 6.9 +/- 2.4 dB vs 6.5 +/- 3.6 dB were found. Kappa coefficients denote marginal accordance (kappa: 0.11-0.38) for area deviations. In a total of 225 areas HFA detected 191 deviations and FDP 165. HFA measured more negative deviation compared with FDP in the case of MD < -15 dB. The reproducibility was 0.98 (MD) and 0.92 (PSD) for FDP and 0.98 (MD) and 0.95 (PSD) for HFA (95% confidence interval). CONCLUSIONS: There was great conformity between FDP and HFA in glaucoma patients. HFA detected more deviations in the total deviation probability plots than FDP. There was a high reproducibility of both methods. FDP is an appropriate tool for detecting visual field loss in glaucoma patients.

Adult↗
PubMed2001

Octreotide reduces vitreous hemorrhage and loss of visual acuity risk in patients with high-risk proliferative diabetic retinopathy.

OBJECTIVE: Growth hormone and insulin-like growth factor-I have been implicated as strong promoters of proliferative diabetic retinopathy. We studied reduction of bleeding and preservation of visual acuity by treatment with the long-acting somatostatin analogue, octreotide, in diabetic patients at an advanced stage of proliferative diabetic retinopathy. RESEARCH DESIGN AND METHODS: Randomized trial in a University hospital setting. Reading ophthalmologists were masked for octreotide use, diabetologists were aware of that treatment. Nine patients received 100 microg tid octreotide (verum) subcutaneously for a maximum of 36 months. Nine diabetics served as controls, no placebo treatment was used. Episodes of vitreous hemorrhages were counted, measurement of visual acuity, estimation of neovascularization by stereoscopic fundus photography and fluorescein angiography were carried out. RESULTS: After 3 years of treatment, the incidence of vitreous hemorrhages and the need for vitreoretinal surgery was significantly lower (log rank test p = 0.002) in the octreotide-treated patients. Visual acuity was preserved and significantly better in the octreotide treated group compared to controls (p = 0.05). CONCLUSIONS: In diabetics with high-risk proliferative retinopathy after full scatter laser coagulation, octreotide reduced the number of vitreous hemorrhages, preserving visual acuity.

Adult↗
PubMed2001

[Malignant transformation of a choroidal nevus 6 years after brachytherapy of a non-contiguous choroidal melanoma - a case report and review of literature].

BACKGROUND: Brachytherapy is a well established procedure for treatment of malignant choroidal processes. Approximately 5 % of the cases, will show local recurrences within 6 years. We report a patient who has developed a malignant transformation of an uveal nevus following brachytherapy of a non-contiguous uveal melanoma. In addition, we reviewed the literature concerning similar cases. HISTORY AND SIGNS: In 1991 a Ruthenium application was performed on a 65-year old patient suffering of an equatorial malignant choroidal melanoma. At that time, a nevus at the posterior pole was present. From 1997 to 1998 the nevus continuously increased in size. Visual acuity decreased and a retinal detachment developed. Combining the clinical and the sonographic findings, the diagnosis of a malignant melanoma arising of a nevus was established. Enucleation was performed in 1998. THERAPY AND OUTCOME: Histologic examination revealed the diagnosis of an epithelioid-cell-type malignant uveal melanoma arising in a nevus. Till now, the patient is free of metastatic disease. CONCLUSION: Non-contiguous development of uveal melanomas in the same eye are extremely rare. We could identify in the literature 5 cases of non-contiguous melanomas following brachytherapy of an uveal melanoma. In none of these cases, the secondary melanoma has arisen in a nevus. Follow-up examination of patients with uveal melanoma treated with brachytherapy should include not only examination of the treated area, but also the whole fundus of the eye in order to recognize secondary tumours as early as possible.

Aged↗
PubMed2001

[Diffuse melanocytic nevus of the iris and absolute glaucoma].

BACKGROUND: Ferry et al. (8) showed that 35 % of eyes which have been enucleated because of a clinically suspected malignant iris lesion did not reveal a histologically malignant iris tumor. PATIENT: A 43-year old male presented with a blind, painful left eye, which has developed over a time period of 6 months. Ophthalmologic examination revealed the presence of pigmented iris stromal lesions associated with diffuse pigmentation of the chamber angle and the development of absolute glaucoma. A diffuse iridociliary malignant melanoma (ring melanoma) was suspected and the blind painful eye was enucleated. Histologic examination revealed the presence of a benign melanocytic lesion, i.e. a spindle cell nevus of the iris with surface plaques causing diffuse extension of the chamber angle, trabecular meshwork, Schlemm's canal, and the ciliary body. CONCLUSION: The malignant potential of iris lesions may be difficult to assess on clinical grounds only. Histologically, benign melanocytic proliferation may cause diffuse extension into the ciliary body as well as the chamber angle leading to an increase in intraocular pressure. In order to reach a final diagnosis a biopsy of the lesion is necessary.

Adult↗
PubMed2001

[Optic nerve evulsion: Metaanalysis].

BACKGROUND: Evulsion of the optic nerve is a rare form of traumatic optic neuropathy. It is a rupture of the optic nerve at the disc without damage of its sheaths occurring in association with a blunt skull trauma or a blunt bulbar trauma. MATERIAL AND METHODS: We searched the literature using Medline database for all articles with evulsion of the optic nerve. The bibliographies of the papers found therein were used to get a complete review. The data were analyzed with special regard to age, sex, mechanism of injury, and (if available) defects of visual field. RESULTS: Sixty-three patients with a mean age of 22 years (range 4 to 60 years) were included in the study. In 22 patients (35 %) a partial and in 41 patients (65 %) a complete evulsion was present. In 31 patients (49 %) the cause was a small blunt object or finger that stroke the eye or entered the orbita. In 19 patients (30 %) a severe blunt skull trauma had occurred. The analysis of visual fields in eyes with partial evulsion of the optic nerve revealed a defect in the superior visual field in 6 of 12 patients and a defect in the inferonasal visual field in 3 of 12 patients. PATHOGENESIS: Our review suggests that the most common mechanism of injury is a severe rotation of the eye leading to rupture of the optic nerve fibers and an anterior displacement of the bulbus, possibly with deformation of the posterior eye walls.

Adolescent↗
PubMed2001

[Scanning electron microscopic study of 12 lenses of two types of soft acrylic intraocular lenses].

BACKGROUND: Evaluation of the surface properties of two models of one-piece foldable acrylic intraocular lenses (IOLs) before and after folding and passing the IOLs through an injector. METHODS: We studied two foldable IOL models made of a polymethacrylate/2-hydroxyethylmethacrylate copolymer: EasAcryl 1(R) (Chiron) and Raysoft(R) 547H (Rayner). Twelve IOLs of each design with different diopters were examined. Light and scanning electron microscopy were performed before and after IOL folding and passing the IOLs through a Micra G103 injector (Chiron Adatomed) and an IC-2BU inserter cartridge (Chiron Microsert II). RESULTS: All IOLs presented a homogeneous surface and smoothly finished edges of haptics and optics. The inner edges of all IOL haptics and the optic edges of some IOLs had ridges at high magnifications. No IOL demonstrated any folding defects of the optic such as a folding line or scratches. Three of 16 folded IOLs showed defects or cracking of the IOL haptics due to incomplete placement in the inserter cartridge. CONCLUSIONS: The two models of soft acrylic intraocular lenses showed excellent surface quality. After folding and injection process no alteration of the optics was detected in any of the IOLs. However, the IOLs need careful placement in the inserter cartridge to avoid haptic damage.

Acrylates↗
PubMed2000

[Age-related maculopathy. Comparative studies of patients, their children and healthy controls].

BACKGROUND: The aim of this study was to evaluate prospectively whether there are differences in spectrometrically measurable parameters of the fundus between patients with early and late age-related maculopathy (ARM), the children of the ARM patients (F1 generation) and normals. METHOD: Using the "Jenaer Imaging Spectrometer", retinal oxygen saturation, xanthophyll, and intrinsic fluorescence were measured; the spatial distribution of xanthophyll was determined using the Rodenstock SLO 101 model. RESULTS: Xanthophyll is reduced in late ARM as compared to the F1 generation and the control group (alpha < 0.01). The different fluorescence spectra, measured at shortwave and at longwave excitation, suggest the presence of more than one fluorophore. Furthermore, the components of the fluorophores seem to be different between patients with ARM and their F1 generation. The longwave autofluorescence is age-dependent only in late ARM (r2 = 0.81). For the first time, we found an alteration in oxygen saturation in retinal vessels in patients with ARM. CONCLUSIONS: Xanthophyll is reduced only in late ARM. Autofluorescence and oxygen saturation are different between ARM patients, the F1 generation and normals, however, we were not able to identify a genetically based predisposition concerning the parameters studied.

Adult↗
PubMed2000

[Effect of octreotide combined with growth factors on proliferation of RPE cells in vitro].

BACKGROUND: The long-acting somatostatin analogue octreotide is used as a therapeutic option for patients with diabetic retinopathy and age-related macular degeneration. Growth factors, such as EGF, bFGF, VEGF, and PDGF, have been implicated in the pathogenesis of these diseases. The aim of this study was to investigate the effect of octreotide on the growth-factor-induced proliferation of bovine retinal pigment epithelial (RPE) cells in vitro. METHODS: RPE cells were assayed for proliferation as measured by (3H)-thymidine uptake (ccpm). Bovine RPE cells at passage 3-8 were seeded in a 96-well plate and incubated for a 24-h period with a minimum medium followed by a 24-h incubation with the different growth factors at a concentration of 10 ng/ml with and without 5 x 10(-5) M octreotide. In a different assay the cells were incubated with octreotide at 5 x 10(-10)-5 x 10(-4) M. Afterwards the cells were pulsed with 5 microCi/ml (3H)-thymidine for 12 h, and the incorporated radioactivity was measured on glass fiber filters in a beta-counter (mean +/- SEM ccpm). The Wilcoxon Signed Rank test and the student's t-test were used for statistical analyses. RESULTS: There was a biphasic effect of octreotide on RPE cell proliferation. Exposure of RPE cells to PDGF (20,225 +/- 3304 ccpm) and bFGF (3441 +/- 539 ccpm) resulted in a significantly higher proliferation compared to control medium (1543 +/- 352 ccpm) (p < 0.05). No difference was found for EGF (2385 +/- 383 ccpm). For VEGF (776 +/- 83 ccpm) a significant reduction in RPE cell proliferation was found (P < 0.05). There was a significant reduction in proliferation of RPE cells with PDGF, bFGF, and EGF in combination with octreotide versus growth factors alone (octreotide in combination with PDGF 308 +/- 82 ccpm, with bFGF 229 +/- 88 ccpm, with EGF 2362 +/- 91 ccpm) (p < 0.005). VEGF in combination with octreotide resulted in a significant inhibition of RPE cell proliferation compared to VEGF alone (p < 0.0005). CONCLUSION: The data suggest that there is an inhibitory effect of octreotide on RPE cell proliferation of bovine RPE cells and on the increased proliferation of bovine RPE cells induced by PDGF and bFGF. An enhanced inhibitory effect is found for the combination of octreotide and VEGF.

Animals↗
PubMed2000

[Morphometric changes in the choriocapillaris and choroid in eyes with advanced glaucoma damage].

BACKGROUND: In addition to elevated intraocular pressure, a compromised ocular blood supply has been implicated in the pathogenesis of primary open-angle glaucoma (PCOG). METHODS AND MATERIALS: We analyzed 20 eyebank eyes with end-stage PCOG and compared these with 20 age-matched controls. The following variables were measured: density and diameter of large choroidal vessels in the macular and equatorial choroid; thickness of the choroid in the macular and equatorial region; and density and thickness of choriocapillaris in the macular, peripapillary, and equatorial choroid. RESULTS: Eyes with glaucoma displayed a lower density of the capillaries of the choriocapillaris than control eyes in the macular, temporal peripapillary, and equatorial choroid, with 0.50 vs. 0.55 (P = 0.018), 0.46 vs. 0.51 (P = 0.016), and 0.50 vs. 0.55 (P = 0.038), respectively. Assessment of large choroidal vessels in the macular choroid showed that eyes with glaucoma had less density of veins (11.7 vs. 38.9/mm2; P < 0.001) and arteries (7.7 vs. 12.4/mm2; P = 0.005) and arteries with a higher diameter (45.6 vs. 28.2 microns; P < 0.001) than control eyes. The large vessels in the equatorial choroid displayed no significant difference in diameter but a lower density (21.2 vs. 44.1/mm2; P = 0.017) in eyes with glaucomatous damage than controls. CONCLUSION: Eyes with advanced glaucomatous damage after long-standing PCOG exhibit many changes in the choroidal vasculature. We cannot conclude from our study whether the observed vascular changes in the choroid are primary pathogenic factors or secondary phenomena.

Capillaries↗
PubMed2000

[Effects of carotid artery thrombendarterectomy on pulsatile ocular blood flow].

UNLABELLED: Successful operations of clinically significant carotid artery stenosis by carotid endarterectomy (CEA) are leading to a better perfusion in the region of this artery. It still creates problems to make a statement about cerebral and ocular perfusion during the operation. METHODS: In 10 patients who underwent a CEA the pulse amplitude (PA) of the intraocular pressure (IOP) was measured intraoperatively by a pneumotomography (OBF-Systems, U.K.) and the so called pulsatile ocular blood flow (pOBF) was determined. The middle arterial blood pressure (MAP) was taken invasively during the operation. RESULTS: During the clamping phases no PA could be recorded. PA (p = 0.04) and pOBF (p = 0.028) increased on the side which had been operated on. No correlations of PA and pOBF to MAP were found. CONCLUSION: This method can prove an increased pulsatile ocular blood flow after successful CEA.

Aged↗