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.

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.

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.