[Long-term results after pars plana vitrectomy with 25 gauge technique]. / Langzeitergebnisse nach Pars-plana-Vitrektomie mit 25-Gauge-Technik.

BACKGROUND: The 25-gauge technique of pars plana vitrectomy appears to be a very suitable method, especially for patients with pathological epiretinal alterations of the macula. However, the procedure has been criticized for insufficient impermeability with an increased risk of endophthalmitis and that the flexibility of instruments is too high. METHOD: Between 2002 and 2006, 625 eyes from 620 patients were operated on using the 25-gauge technique. Epiretinal membranes in different stages had been diagnosed in all patients. The operations were performed by only one surgeon. RESULTS: The epiretinal membranes were successfully removed in all patients and 329 eyes were analyzed with long-term follow up over 3.1 years. The mean improvement in visual acuity before and after surgery was -0.41 in LogMAR. One week postoperatively normal IOP was observed in all cases. The mean preoperative IOP was 17 mmHg and 8 mmHg 1 day after surgery. In nine patients with postoperative hypotony and choroidal detachment an additional suture was required and seven patients developed a retinal detachment. Endophthalmitis was not observed in any of the patients during the follow-up period. CONCLUSIONS: The 25-gauge PPV technique appears to be effective and safe for the treatment of epiretinal membranes. The operation has low complication rates with respect to endophthalmitis or retinal detachment. The procedure has recently been further improved by using more stable instruments and better lighting.

Macular pigment in the human retina: histological evaluation of localization and distribution.

PURPOSE: Clinical investigations have demonstrated variation in both the peak optical density and the spatial distribution of macular pigment. To confirm these impressions histologically, the present study examined the distribution of macular pigment in the human retina. MATERIALS AND METHODS: The macular retina of 11 donor eyes of different ages (28-91 years) were examined histologically on 100 microm vibratome sections directly, without further staining. Measurements were made in two dimensions: (1) adding the number of macular sections with visible macular pigment, and (2) direct measurement of the extension of macular pigment in the foveolar section, which visibly contained the most macular pigment. RESULTS: The measurements with two methods demonstrated good correlation. The macula demonstrated a variation in the spatial extension of the visible macular pigment between 200 and 900 microm diameter around the centre of the fovea, which was also found when direct measurements were taken. There was no correlation with the donor age. The main location of macular pigment was in the layer of the fibres of Henle in the fovea and in the inner nuclear layer at the parafoveal site. CONCLUSIONS: Histologically, a wide variation of the spatial distribution of macular pigment was found that confirms clinical observations. The primary localization of human macular pigment is in the inner retinal layers.

[Radial optic neurotomy for ischemic central retinal vein occlusion]. / Therapie des Zentralvenenverschlusses durch radiäre Optikusneurotomie (RON). Funktionelle und morphologische Langzeitbeobachtungen.

INTRODUCTION: Occlusion of the central retinal vein (CRVO) is the second most frequent cause for blindness in the course of pathological changes of the vascular system. Vitreous haemorrhages and neovascular glaucoma are known as serious complications. Clinically accepted guidelines for treating CRVO do not exist up to now. In this report our results after radial optic neurotomy (RON) of patients suffering from CRVO associated with visual deterioration are summarised. PATIENTS AND METHOD: 78 patients (mean age 68 year, gender: 41 male, 37 female) with visual acuity of 0.2 or worse were treated with RON. Mean follow-up was 13 months. 35 patients underwent previously haemodilution treatment without success. Visual acuity tests, fluorescein angiographic appearance, OCT and postoperative complications were analysed, in 47 % additionally VEP, ERG and the visual field were evaluated. RON was carried out by conventional pars plana vitrectomy. Neurotomy was performed at the nasal side of the optic disc in all cases. Neither ILM peeling nor gas tamponade was used. Follow-up examinations were carried out after 2 and 4 weeks, after 3 and 6 months and after 3 years. RESULTS: Improvement of morphological parameters could be registered in 95 % of our patients by means of fluorescein angiography or OCT. Visual acuity improved in 81 % and worsened in 10 %. After 6 months patients with non-ischaemic CRVO had a significantly better visual acuity compared to patients with ischaemic CRVO. A retino-choroidal anastomosis could be observed in 38 (48 %) eyes, all these patients experienced visual improvement. The results of VEP and ERG showed partial recovery in all cases. A temporal visual field defect occurred postoperatively in 95 % of our patients. CONCLUSION: Visual acuity of patients suffering from non-ischaemic CRVO with low preoperative visual acuity and short history may improve after RON. Frequent complications were temporal field defects and vitreous haemorrhage. Further randomised studies are necessary to compare these results after RON with other alternative therapeutic procedures, for example, intravitreal injection of VEGF inhibitors.

[Intraocular application of bevacizumab for the treatment of choroidal neovascularization secondary to angioid streaks]. / Intraokulare Injektion von Bevacizumab - Eine mögliche Therapie der sekundären CNV bei angioid streaks.

Angioid streaks are the typical ophthalmological manifestation of the systemic disease pseudoxanthoma elasiticum. Fundoscopy reveals angioid streaks as irregular dark brownish lines radiating from the area around the optic disc. Choroidal neovascularization (CNV) is the major cause of severe visual loss in patients with angioid streaks. Argon-laser treatment of CNV secondary to angioid streaks shows poor results. Photodynamic therapy (PDT) with verteporfin does not seem to be an effective treatment for achieving stabilization of visual acuity and lesion size in CNV secondary to angioid streaks. Results after a combination of the intravitreal application of triamcinolone with PDT did not show the expected benefit. In the era of promising new intravitreal treatments for patients suffering from age-related macular degeneration, it is interesting to observe this effect of angiogenesis inhibitors (bevacizumab, ranibizumab, pegaptanib) in patients with neovascilarization secondary to angioid streaks. In our case, we observed a deterioration in visual acuity and leakage of the CNV after treatment with PDT alone. However, after the intravitreal injection of bevacizumab, we observed an improvement in vision, and the area of neovascularization changed into a fibrotic scar. A controlled study with long-term results is needed to definitively evaluate this kind of treatment.

Macular pigment optical density measurement in autofluorescence imaging: comparison of one- and two-wavelength methods.

BACKGROUND: Measurement of macular pigment (MP) can be performed by analysis of autofluorescence (AF) images. These can be obtained by standard 488-nm argon-imaging alone (one wavelength, 1-Lambda) or with additional digital subtraction of a second image at 514 nm (two wavelengths, 2-Lambda). The analyses are easy to perform, and we present a comparison of both methods and investigate their reliability and repeatability. METHODS: Inter-individual variability of MP optical density (MPOD) measurements was assessed in single eyes of 120 subjects with a modified Heidelberg retina angiograph (HRA). MPOD values obtained with one (488 nm) Lambda (MPOD(1Lambda)) were compared with those obtained with two (488 nm and 514 nm) Lambda (MPOD(2Lambda)). To test the repeatability of the two methods, 20 subjects were subjected to five repeated measurements. RESULTS: Among 120 individuals, mean MPOD(1Lambda) at 0.5 degrees eccentricity was 0.59 (range 0.06-1.32), mean MPOD(2Lambda) was 0.5 (range 0.01-1.21). Apart from this systematic difference, 1-Lambda and 2-Lambda measurements at 0.5 degrees agreed well across the range of MPOD values (beta=0.964, around the fovea, a systematic difference (0.11) was accompanied by declining agreement at higher MPOD values (beta=0.669, 95% CI 0.519-0.844; R=0.48). Among 20 subjects with five repeated measurements, the reliability ratio was 0.97 for 1-Lambda and 0.94 for 2-Lambda at 0.5 degrees and 0.93 and 0.94, respectively, at a distance of 2 degrees. CONCLUSIONS: Both methods showed a high repeatability with little influence of measurement error. They agree well at the fovea centre in terms of ranking individuals according to their MPOD, but provide increasingly deviating results at a distance of 2 degrees around the fovea, probably because the 1-Lambda method, in contrast to the 2-Lambda method, cannot compensate for disruptive influences and for heterogeneous distributions of the lipofuscin fluorophores. The 1-Lambda method can be performed by standard HRA and could therefore be used for screening in multicentre studies, but only approaches the actual amounts of MP. The 2-Lambda method remains the more precise method for MPOD measurement in autofluorescence imaging.

Interferon as a treatment for uveitis associated with multiple sclerosis.

AIM: In addition to optic neuritis (ON), multiple sclerosis (MS) may also involve the eye with a typically bilateral intermediate uveitis. The aim of this pilot study was to evaluate the efficacy of type I interferons (IFN) for the treatment of MS associated uveitis. METHODS: In this non-randomised, retrospective observational case series 13 patients (eight female, five male) with proved MS and associated uveitis from five uveitis centres who were treated with interferon beta1a were included. Visual acuity (VA), cell count in the aqueous humour and vitreous, as well as the presence of cystoid macula oedema (CMO) were observed. RESULTS: All except one patient had a bilateral form of intermediate uveitis (total of 24 eyes). Seven patients had documented CMO before IFN treatment (n = 13 eyes). Median duration of treatment was 24.6 months (range 7.9-78.7). VA improved in 17 eyes (comparing VA before therapy and at last follow up); while 10 eyes (36%) improved >or=3 Snellen lines. Aqueous cell count improved by 1.2 (SD 1.1) grades in all eyes. Vitreous cell count improved by 1.7 (1.4) in all eyes. Only two patients still had minimal CMO on last follow up angiographically. CMO resolved after or during IFN treatment in nine eyes. CONCLUSIONS: IFN has been shown to have beneficial effects in patients with MS and/or ON. As shown in the models of experimental allergic encephalomyelitis (EAE) and uveitis, the neurological and ophthalmological manifestations seem to share similar pathogenic mechanisms. Treatment of MS associated uveitis with IFN appears to have beneficial effects on VA, intraocular inflammation activity, and the presence of CMO.

Donepezil for dementia in Parkinson's disease: a randomised, double blind, placebo controlled, crossover study.

OBJECTIVE: To study the safety and efficacy of a cholinesterase inhibitor, donepezil hydrochloride, for the treatment of dementia in Parkinson's disease (PD). METHODS: This was a randomised double blind, placebo controlled, crossover study in 22 subjects with PD and dementia. Participants were randomised to receive either donepezil followed by identical placebo, or placebo followed by donepezil. Donepezil was administered at 5-10 mg/day. Treatment periods were 10 weeks with a washout period of 6 weeks between the two periods. The primary outcome measure was the Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAScog). RESULTS: Donepezil was well tolerated and most adverse events were mild. There was no worsening of PD symptoms as measured by the total or motor sections of the Unified Parkinson's Disease Rating Scale.There was a 1.9 point trend toward better scores on the ADAScog on treatment compared with placebo that was not statistically significant. The secondary cognitive measures showed a statistically significant 2 point benefit on the Mini Mental Status Examination and no change on the Mattis Dementia Rating Scale (MDRS). The Clinical Global Impression of Change (CGI) showed a significant 0.37 point improvement on donepezil. No improvement was observed on the MDRS or the Brief Psychiatric Rating Scale. Carryover between treatment periods was observed but was not statistically significant. CONCLUSIONS: Donepezil was well tolerated and did not worsen PD. There may be a modest benefit on aspects of cognitive function. The possible clinical benefit measured by CGI was reflected in only one of the cognitive scales used in this study.

Macular pigment: quantitative analysis on autofluorescence images.

BACKGROUND: Macular pigment (MP) reduces oxidative damage in the central retina and can be quantified by flicker-photometric analysis (HFP) of MP optical density. These analyses demonstrate a very good correlation with central absorption by MP on autofluorescence (AF) images. With these techniques different types of MP-distribution have been described. In the present study a quantification analysis of MP in AF images was developed to verify these MP types and to compare MP distribution patterns between healthy individuals and those with age-related macular degeneration (AMD). METHODS: AF images (HRA) were analysed with respect to the area of central and paracentral absorption in 400 eyes with a computerised analysis program of MP optical density. The patients were between 41 and 90 years old (mean 67.2 years); 168 were male and 232 female, and 253 had early AMD and 147 showed no AMD characteristics. The central MP concentrations (peak) were measured, the amount of MP values within the first 8-pixel radius ("C"), the total amount of MP within a 120-pixel radius ("T") were calculated as the volume of the MP values over the regarded radius and the C/T ratio was registered. RESULTS: Four types of MP distribution (type 1, intense central and paracentral MP; type 2, less intense central and paracentral MP; type 3, only central MP; type 4, only paracentral MP) were identified. The differences in MP distribution were confirmed and clearly characterised by quantitative analyses of peak, total MP ("T"), central MP ("C") and C/T ratio: mean peak in type 1, 0.65; type 2, 0.42; type 3, 0.42; type 4, 0.29; mean total amount of MP in 120-pixel radius ("T") in type 1, 5829.0; type 2, 4412.5; type 3, 2709; type 4, 4302.8. MP types with lower levels of MP were significantly more often observed in the AMD group (AMD: type 1, 120=47.4%; types 2-4, 133=52.6%; healthy eyes: type 1, 112=76.2%; types 2-4, 35=23.8%) ( P<0.0001) CONCLUSIONS: Analysis of MP on AF images is a quantitative method for investigation of MP. With this method a wide variation in concentration and distribution of MP could be seen in the population. Four different types of MP distribution could be characterised and quantitatively distinguished. Reduced levels of MP seem to be associated with a higher risk of development of AMD as they were significantly more often observed in the AMD group. This strategy of quantitative MP analysis on AF images is easily practicable and may be used in further studies to investigate the role of MP as a potential risk factor for AMD.

A classic watershed infarct.

A consequence of severe hypotension, watershed infarcts lead to significant morbidity and mortality rates of 10% per year. The best preventive measure is to control systemic hemodynamic factors. Identification of high risk patients may help focus these efforts. Unfortunately, our patient suffered an ischemic episode with rapid onset resulting in minimal therapeutic options.

Molecular characterization and organization of porin from Rhodobacter capsulatus strain 37B4.

The primary and atomic structures of the porin protein from Rhodobacter (Rb.) capsulatus strain 37b4 were determined several years ago by peptide sequencing and X-ray crystallography. In this work the gene encoding this porin (named porCa) was cloned and sequenced. The porin open reading frame encodes 320 amino acids-a mature protein of 300 residues (molecular mass 31 552 kDa) and a presequence of 20 amino acids. Our deduced amino-acid sequence was directly confirmed by purifying the porin protein from the same bacterial strain and sequencing the amino terminus as well as several peptides derived from trypsin digestion. However, comparison of this deduced amino-acid sequence with the published primary structure of this porin, nominally from the same strain (but cultivated for ca. 30 years in a different laboratory) reveals seven differences in the amino-acid sequence at the following positions in the mature protein (published/present): 59 (Gly/Ala), 123 (Tyr/Asn), 135 Ser/Thr), 189 (Ile/Val), 196 (Asn/His), 231 (Ala/Thr) and 238 (Ser/deleted). Surprisingly, analysis of the positioning of these mutations revealed that they are located exclusively on transmembrane strands, with two of them deeply buried within the structure. These mutations may in fact have only marginal influence on porin structure and function. Northern blot analysis revealed that porCa encodes an RNA transcript of 1070 nucleotides. No differential response in the abundance or size of this mRNA was seen upon growth under phototrophic/anaerobic vs. chemotrophic/aerobic conditions, under high or low osmotic pressure. Primer extension experiments revealed a transcription start site 73 bases upstream from the ATG translation start, juxtaposed to the identified putative promoter region. Fusion of lacZ with this putative promoter region (using a 288-bp upstream region) revealed similar promoter activity in beta-galactosidase assays under both physiological conditions tested, again suggesting that this gene is constitutively expressed. The molecular genetic characterization described in this work opens the way for structure-function studies by site-directed mutagenesis.

Molecular analysis of the Rhodobacter capsulatus B10 porin (porCa) gene; purification and biochemical characterisation of the porin protein.

The pore-forming outer-membrane protein from Rhodobacter (R.) capsulatus (wild-type B10 strain) was isolated and purified under non-denaturing conditions. The monomer unit of the isolated porin has a molecular mass of about 28 kDa, as judged by SDS-PAGE, whereas the native protein migrates at 75 kDa. This suggests that the native porin from R. capsulatus B10 exists in a trimeric form. The N-terminal amino acid sequence was used to design an oligonucleotide which was utilised to screen a pBluescript library containing EcoRI fragments of R. capsulatus B10 DNA. A 5.3-kb DNA fragment, which included the entire structural porin gene (named porCa) and its flanking regions, was identified. A 945-bp open reading frame, coding for a mature protein of 295 amino acid residues (molecular mass 30,586 Da) plus a presequence of 20 amino acids, was found. The directly determined sequence of the amino-terminus and of four tryptic peptides of the purified porin matched perfectly with the deduced amino acid sequence. Northern blot analysis showed that the porin gene encodes an RNA transcript of 1050 nucleotides. In addition, there is no differential response in terms of either the size or abundance of the mRNA under different environmental conditions. Primer extension experiments confirmed a putative promoter upstream of the porin gene; and localised the RNA transcription start site 73 bp upstream of the ATG start codon, which is close to the putative promoter (-10/-35). As shown using a plasmid-borne porin-lacZ gene fusion, [in R. capsulatus] expression of the lacZ gene under the control of the porCa promoter is not regulated under the two different environmental conditions tested. The promoter of the porin gene was localised within 305 bp upstream of the ATG start codon. A model of the 3-D structure of porin B10 was deduced by comparative modelling with the R. capsulatus 37b4 and Rhodopseudomonas blastica porin crystallographic structures using the ProMod program on the Swiss-Model protein modelling e-mail Server. Analysis of the B10 sequence and comparison of a model of the B10 porin structure with the crystallographic structure of porin from the capsuleless strain 37B4 has revealed some important differences at the level of the protein surface, the pore and the putative ligand binding site.

Differences between porin isolated from Rhodobacter capsulatus B10 and 37b4.

Porin was isolated from Rhodobacter (Rb.) capsulatus wild type B10, as well as from Rb. capsulatus 37b4 as a control. The porin from Rb. capsulatus B10 shows significant differences to that of Rb. capsulatus 37b4 in N-terminal sequence, amino acid composition and molecular mass. The apparent molecular mass of the purified porin from Rb. capsulatus B10 is about 28 kDa by SDS-PAGE, whereas the native porin trimer migrates at 75 kDa. For Rb. capsulatus 37b4 the molecular mass of the momomer is about 30 kDa and for the trimer about 76 kDa. These differences may be related to the morphological differences between the two wild type strains. Rb. capsulatus B10 has an extracellular capsule whereas Rb. capsulatus 37b4 is capsuleless. The native proteins from both wild types showed similar single channel conductance measurements in black lipid membranes. The B10 porin has been crystallised using the detergent beta-d-octyl-gluco-pyranoside. The crystals diffracted to 3 A and belong to the orthorhombic space-group P212121. The crystal packing could be elucidated by molecular replacement.