Biomedical subjects

M Trieschmann

Publications and source records attributed to M Trieschmann.

4 recordsLinked to original sources

PubMed2006

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.

Adult↗

PubMed2005

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.

Adult↗

PubMed2003

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.

Adult↗

PubMed2001

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.

Aged↗