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Biomedical subjects

G E Lang

Publications and source records attributed to G E Lang.

At least 19 recordsLinked to original sources
PubMed2006

[Comparison of Preferential Hyperacuity Perimeter (PHP) test and Amsler grid test in the diagnosis of different stages of age-related macular degeneration].

BACKGROUND: Age-related macular degeneration (ARMD) is the leading cause of blindness in people over 65 years of age. A rapid loss of vision occurs especially in cases with choroidal neovascularisation. Early detection of ARMD and timely treatment are mandatory. We have prospectively studied the results of two diagnostic self tests for the early detection of metamorphopsia and scotoma, the PHP test and the Amsler grid test, in different stages of ARMD. PATIENTS AND METHODS: Patients with ARMD and best corrected visual acuity of 6/30 or better (Snellen charts) were examined with a standardised protocol, including supervised Amsler grid examination and PHP, a new device for metamorphopsia or scotoma measurement, based on the hyperacuity phenomenon in the central 14 degrees of the visual field. The stages of ARMD were independently graded in a masked fashion by stereoscopic ophthalmoscopy, stereoscopic fundus colour photographs, fluorescein angiography, and OCT. The patients were subdivided into 3 non-neovascular groups [early, late (RPE atrophy > 175 microm) and geographic atrophy], a neovascular group (classic and occult CNV) and an age-matched control group (healthy volunteers). RESULTS: 140 patients, with ages ranging from 50 to 90 years (median 68 years), were included in the study. Best corrected visual acuity ranged from 6/30 to 6/6 with a median of 6/12. 95 patients were diagnosed as non-neovascular ARMD. Thirty eyes had early ARMD (9 were tested positive by the PHP test and 9 by the Amsler grid test), and 50 late ARMD (positive: PHP test 23, Amsler grid test 26). The group with geographic atrophy consisted of 15 eyes (positive: PHP test 13, Amsler grid test 10). Forty-five patients presented with neovascular ARMD (positive: PHP test 38, Amsler grid test 36), 34 volunteers served as control group (positive: PHP test 1, Amsler grid test 5). CONCLUSIONS: The PHP and Amsler grid tests revealed comparable results detecting metamorphopsia and scotoma in early ARMD (30 vs. 30 %) and late ARMD (46 vs. 52 %). However, the PHP test more often revealed disease-related functional changes in the groups of geographic atrophy (87 vs. 67 %) and neovascular ARMD (84 vs. 80 %). This implies that the PHP and Amsler grid self tests are useful tools for detection of ARMD and that the PHP test has a greater sensitivity in the groups of geographic atrophy and neovascular AMD.

Aged↗
PubMed2006

[Retinal angiomatous proliferation in age-related macular degeneration].

BACKGROUND: Angiomatous proliferation in ARMD originates from the retina and extends into the subretinal space. Retinal angiomatous proliferation (RAP) is diagnosed with angiography. This study investigates the characteristics of RAP in optical coherence tomography (OCT) and correlates them with clinical and fluorescein angiographic findings. METHODS: 327 consecutive patients with age-related macular degeneration (ARMD) were retrospectively examined using a standardised protocol. The protocol included best corrected visual acuity (BCVA), binocular ophthalmoscopy, fundus photography, fluorescein angiography (FAG) and OCT. The OCT and angiographic findings were graded in 3 RAP stages. RESULTS: 32 of 327 (9.79 %) patients (45 eyes) had RAP. The age ranged from 56 to 90 years (median: 79 years). 9 eyes presented RAP stage I, 23 stage II and 13 stage III. BCVA ranged from 0.01 to 0.7 (median: 0.2). OCT foveal minimum was 136 to 722 microns (median: 327). 33 (73 %) eyes showed a detachment of retinal pigment epithelium (RPE). Macular oedema was found in 43 (96 %) eyes. Cystoid macular oedema was seen in 36 (80 %) eyes. In stage II, 22 eyes (96 %) showed an RPE detachment, in stage III 11 eyes (85 %). 11 (85 %) eyes in stage III showed retinal-choroidal anastomosis. CONCLUSIONS: RAP was found in 9.79 % of the patients with ARMD. The OCT is helpful in detection of RPE detachment, macular oedema and cystoid changes in RAP. RAP and retinal-choroidal anastomosis should be identified because of the possibly poor prognosis.

Aged↗
PubMed2005

[Iris neovascularization as a complication of central artery occlusion].

BACKGROUND: Iris neovascularization (IN) with a secondary angle closure glaucoma is a complication of central retinal artery occlusion (CRAO). Its incidence is greatly underestimated. MATERIALS AND METHODS: In a retrospective study we analyzed all patients with CRAO seen within 2 years who were treated in our department. We looked especially for the frequency of the occurrence of IN. RESULTS: In 27 patients with CRAO, 5 developed an IN with a secondary neovascular glaucoma with high intraocular pressure. Thus, the frequency of IN was 18 % in our patients. The IN occurred 2 months to 2 years after the occlusion. Visual acuity in three eyes was between 1/20 and light perception and two eyes had no light perception. In all cases a panretinal laser treatment was performed. Three eyes were additionally treated with a peripheral retinal cryocoagulation and cyclophotocoagulation. In the histories of these patients, diabetes mellitus and arterial hypertension were found. CONCLUSIONS: In previous studies it has been shown, that ischemia/reperfusion injuries of the retina after CRAO predispose to IN (incidence 3 - 18 %). Although it has been shown that the majority of IN occurs within three months, our data show that IN may occur as a severe complication of CRAO even later. Patients should be followed-up closely (including gonioscopy), to diagnose the occurrence of IN early. Recommended treatment is panretinal laser coagulation or -- in the case of a secondary angle closure glaucoma -- cyclophotocoagulation, respectively.

Comorbidity↗
PubMed2005

[CAR syndrome (carcinoma-associated retinopathy syndrome) associated with an adenocarcinoma of the cervix].

BACKGROUND: CAR is a rare paraneoplastic syndrome. It is most commonly associated with small-cell carcinoma of the lung. Specific autoantibodies exist not only against the retina but also against other ocular structures. They induce apoptotic death of retinal photoreceptor cells. CASE REPORT: We report about a 68-year-old patient who presented in February 2003 with progressive visual dysfunction including visual acuity loss and visual field defects of unknown origin, which first manifested in the year 1998. RESULTS: We found a visual acuity of 0.1 in both eyes and concentric visual field defects. The scotopic and photopic electroretinogram was markedly reduced. Uveitis intermedia in both eyes, narrowing of the vessels, especially of the arterioles, optic atrophy and window defects in the retinal pigment epithelium were observed on fluorescein angiography. Due to the patient's report about a resection of an adenocarcinoma of the cervix in June 2002, she was diagnosed as having CAR syndrome. Serologic screening by Western blot analysis revealed different specific autoantibodies against retinal proteins. The patient was treated with corticosteroid pulse therapy. The follow-up showed stable findings. CONCLUSIONS: In patients with progressive visual loss, concentric visual field defects and pathological electroretinogram as well as evidence of uveitis, a CAR syndrome has to be ruled out. One has to take into consideration that visual dysfunction can appear before the primary cancer is diagnosed.

Adenocarcinoma↗
PubMed2004

Elevated serum levels of N(epsilon)-carboxymethyl-lysine, an advanced glycation end product, are associated with proliferative diabetic retinopathy and macular oedema.

AIMS/HYPOTHESIS: Diabetic retinopathy is a frequent microvascular complication. In search of novel risk markers, we analysed the association between serum levels of the major advanced glycation end product N(epsilon)-carboxymethyl-lysine (CML) and prevalence of advanced stages of retinopathy in Type 2 diabetic patients without nephropathy. METHODS: We carried out a case-control study of Type 2 diabetic patients with and without advanced stages of diabetic retinopathy. Retinopathy and macular oedema were defined according to standard criteria. Serum levels of CML were estimated by means of a novel competition-based ELISA assay. RESULTS: Serum levels of CML were significantly different between age-matched controls (n=792; mean value +/- SD: 521+/-134 ng/ml), Type 2 diabetic patients without severe retinopathy (821+/-141 ng/ml; p<0.0001) and Type 2 diabetic patients with proliferative retinopathy (1182+/-346 ng/ml; p<0.0001). Levels of CML greater than 1000 ng/ml represented a 25-fold increase in risk of proliferative retinopathy. Receiver operating characteristics analysis revealed a CML threshold of 1087 ng/ml (100% sensitivity, 93% specificity) for clinically significant macular oedema. CONCLUSIONS/INTERPRETATION: High serum levels of CML were associated with advanced stages of retinopathy. Serum levels were shown to be a progressive risk marker, whereby a level of more than 1000 ng/ml induced a 25-fold increase in risk of proliferative retinopathy and clinically significant macular oedema. Our data suggest that serum levels of CML provide a novel risk marker for advanced stages of diabetic retinopathy in Type 2 diabetic patients.

Biomarkers↗
PubMed2004

[Therapy of diabetic retinopathy with somatostatin analogues].

Somatostatin analogues are a therapeutic option in patients with chronic overproduction of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). These factors are also involved in the pathogenesis of diabetic retinopathy. Somatostatin receptors are expressed in the retina and are therefore possible targets of somatostatin analogues in the treatment of retinal vascular diseases like diabetic retinopathy. The somatostatin analogue octreotide has shown promise as a safe and effective treatment for advanced diabetic retinopathy and diabetic macular edema. The compound blocks the local and systemic production of GH and IGF-1, and thus inhibits the angiogenic effect. Evidence from animal models, and clinical trials in patients with diabetic retinopathy, suggest that octreotide can delay, and to some extent reverse diabetic retinopathy.

Controlled Clinical Trials as Topic↗
PubMed2004

[Pharmacological treatment of diabetic retinopathy].

Chronic overproduction of growth hormone and insulin-like growth factor 1 play an important role in the pathogenesis of diabetic retinopathy. Somatostatin receptors are the targets of somatostatin analogues such as octreotide in the treatment of diabetic retinopathy. Octreotide has shown promise as a safe and effective treatment for advanced diabetic retinopathy and diabetic macular edema. One important pathomechanism in the development of diabetic complications is the activation of protein kinase C induced by high glucose due to an increased diacylglycerol level. The development of a selective PKCss inhibitor enables a new therapeutic approach for the treatment of diabetic retinopathy. Ongoing prospective clinical studies are investigating if treatment with specific PKCss inhibitors can prevent the progression of diabetic retinopathy and diabetic macular edema. The intravitreal injection of triamcinolone acetonide leads to at least temporary improvement of the diffuse diabetic macular edema. Side effects are increase of intraocular pressure, cataract, and endophthalmitis.

Anti-Inflammatory Agents↗
PubMed2004

[Effect of growth factors on the differentiation of porcine lens epithelial cells].

BACKGROUND: Besides cell proliferation, transdifferentiation of lens epithelial cells (LECs) to myofibroblasts is one of the mechanisms of secondary cataract formation. This process is characterized by increased expression of alpha-smooth muscle actin (alpha-SMA). This study investigated the influence of bFGF, TGF-beta2, EGF and IGF-1 on the expression of alpha-SMA in porcine LECs. MATERIALS AND METHODS: Porcine LECs were cultured for 7 days in serum-free medium without or with 1 to 50 ng/ml bFGF, TGF-beta2, EGF or IGF-I. Alpha-SMA was detected immunocytochemically with a mouse monoclonal antibody, and the relative numbers of alpha-SMA-positive cells were calculated. Statistical analysis was performed using Student's unpaired t-test. RESULTS: The ratio of alpha-SMA-positive cells cultured for 7 days in serum-free medium was 36 +/- 11.9 % (mean +/- SD). BFGF significantly reduced this ratio in a dose-dependent manner to 11.2 +/- 7.3 % at a concentration of 50 ng/ml (p < 0.0001). EGF reduced the ratio significantly to 25.1 +/- 15.7 % (p = 0.05) when 50 ng/ml were applied. IGF-1 (10 ng/ml) reduced the relative numbers of transdifferentiated cells to 16.8 +/- 5.8 %, but the reduction was not statistically significant (p = 0.0787). TGF-beta2 (50 ng/ml) slightly increased the relative number of alpha-SMA-positive cells to 44.2 +/- 13.8 %. However, this increase was not significant (p = 0.1202) during a culture period of 7 days. CONCLUSIONS: BFGF and EGF significantly reduced the expression of alpha-SMA by LECs while TGF-beta and IGF-1 had no statistically significant effect. These results suggest that bFGF and EGF do not primarily induce secondary cataract formation by the mechanism of cell transdifferentiation.

Actins↗
PubMed2004

[Prospective comparison of the new indentation tonometer TGdC-01, the non-contact tonometer PT100 and the conventional Goldmann applanation tonometer].

BACKGROUND: This study aimed to compare the results of newer tonometric techniques with standard tonometry for the examples of the Goldmann applanation tonometry (GAT), the indentation tonometer "TGDc-01" and the non-contact tonometer "PT 100". PATIENTS: The study was conducted on a total of 52 healthy subjects. The IOP was measured in each subject on both eyes with all three methods. There were 27 males (51.9 %), 25 females (48.1 %) with an average age of 28.5 years, with a minimum of 13 and a maximum of 79 years. RESULTS: There was no statistically significant difference between the non-contact and the Goldmann applanation tonometry. The measurements were 0.4 mmHg lower, no difference for the left or right side was seen. For IOP higher than 15 mmHg - 0.88 mmHg lower and for IOP lower 15 mmHg - 0.15 mmHg. The results for the "TGDc01" were 0.82 mmHg lower than GAT, the standard deviation was a little higher with 2.9 mmHg compared to 2.67 mmHg for GAT. For IOP higher than 15 mmHg they rose up to - 2.28 mmHg, for IOP lower than 15 mmHg the results for "TGDc-01" were only - 0.2 mmHg lower. There was also an effect with respect to the side, on the right eye the difference was significant with 3.03 mmHg (p = 0.006), in contrast to the left eye with 2.69 mmHg (p = 0.235). For "TGDc01" the standard deviation was higher with 2.9 mmHg compared to 2.6 mmHg for "PT 100". CONCLUSIONS: The non-contact tonometer showed no clinical relevant difference compared with GAT for measuring IOP. The indentation tonometer showed differences for precision, for higher tension IOP the measurement was lower compared with GAT. There was also a significant side difference using the "TGDc-01".

Adolescent↗
PubMed2004

[Comparison of the optical coherence method (Zeiss IOL-Master) with two ultrasonographic biometric methods for the calculation of posterior chamber intraocular lenses after phacoemulsification as part of clinical routine].

BACKGROUND: The aim of this work was to investigate the accuracy of prediction of three different biometric methods for the calculation of posterior chamber intraocular lenses. METHODS: In 59 consecutive patients who underwent extracapsular cataract-extraction with posterior chamber intraocular lens implantation, we compared the refractive results at the first day (D1) and 6 weeks (W6) after surgery with the calculated refraction of three biometric methods: the Carl Zeiss "IOL-Master 99" (IOLM), the Biovision "Echograph Class 1 - Type B" (BIOV) and the Allergan Humphrey "Ultrasonic Biometer Mod. 820" (AHUB). For statistical calculation box-plots, the Wilcoxon signed-rank test and linear regression analysis were used. RESULTS: In all patients the mean of the postoperative refraction was - 0.07 D (SD: 1.41) at day 1 and 0.12 D (SD: 1.18) at week 6. Compared to the postoperative refraction at week 6, the calculated refractive values were higher in all three measuring devices: IOLM: + 0.28 D (SD: 0.67), BIOV: + 0.60 D (SD: 0.88), AHUB: + 0.26 D (SD: 0.92). There were no statistically significant differences between IOLM and BIOV, or respectively, AHUB and BIOV (p < 0.0001), but a significant difference was found between IOLM and AHUB, (p = 0.906). To adjust for systematic differences of the agreement, one can calculate the postoperative refraction at week 6 (REF6) from IOLM by using the linear regression formula: REF6 = 1.1 x IOLM + 0.3. CONCLUSION: A comparison between the three biometric methods and the refractive results at day 1 and week 6 after cataract surgery with implantation of a posterior chamber intraocular lens showed that the calculated mean values obtained from the three biometric methods are higher than the real postoperative refraction. Calculations using the Zeiss IOL-Master and the Allergan Humphrey Ultrasonic Biometer are closer to the patient's postoperative refraction than calculations using the Biovision Echograph.

Aged↗
PubMed2004

Octreotide prevents growth factor-induced proliferation of bovine retinal endothelial cells under hypoxia.

Ocular diseases such as proliferative diabetic retinopathy are the major cause of blindness in industrialized countries. The main pathologic features of these diseases are hypoxia and overproduction of growth factors resulting in pathologic proliferation of endothelial cells and new vessel formation. Particularly, hypoxia and growth factors, such as VEGF, IGF-1, bFGF and TGF beta(2), show a complex interaction in the onset and progression of the diseases. Therefore, to date, most therapeutic strategies for proliferative retinopathies have targeted proliferation of endothelial cells evoked by growth factors. Recently, a synthetic analog of somatostatin, octreotide, has been shown to inhibit the proliferation of various cells in vitro, including endothelial cells. In this study, we have investigated the proliferative response of bovine retinal endothelial cells (BREC) to growth factors under hypoxic conditions and the modulation by octreotide. We found a dose-dependent increase of cell proliferation with VEGF, IGF-1 and bFGF, and inhibition of hypoxia-induced cell proliferation with TGF beta(2). Moreover, growth factor-induced, but not hypoxia-induced, cell proliferation was attenuated in the presence of octreotide. In contrast, TGF beta(2) abolished hypoxia-induced BREC proliferation. Similar to octreotide BIM23027, a somatastatin receptor subtype 2 (SSTR2) receptor agonist was able to attenuate the growth factor-induced proliferation of BREC expressing mRNA and protein for SSTR2. Therefore, we postulate that octreotide exerts its effects mainly through binding to the SSTR2. Taken together, our findings point to octreotide as a promising candidate for the treatment of eye disorders involving growth factor-dependent proliferation of endothelial cells.

Animals↗
PubMed2003

[Diabetic retinopathy. Pathophysiology and therapy of hypoxia-induced inflammation].

Diabetic retinopathy is the most common chronic microvascular complication associated with diabetes mellitus. The development of diabetic retinopathy is a consequence of metabolic dysregulation. Hyperglycemia is a critical factor which is involved in basement membrane thickening, loss of pericytes and endothelial cells, and retinal capillary nonperfusion. We review the molecular basis of diabetic retinopathy and maculopathy and elaborate the role of growth factors and cytokines in the development of diabetic vascular alterations, their specific influence on the cellular interaction between retinal endothelial cells and pericytes, and the role of intravascular blood components.

Animals↗
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

[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↗