No abstract

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 (28-91years) were examined histologically on 100 lm 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 lm 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.

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.

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.

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.