To determine if phenotypic subtypes exist in Stargardt macular dystrophy-fundus flavimaculatus (SMD-FFM). Methods: A cross-sectional study of 63 patients with autosomal recessive SMD-FFM was undertaken. The age of onset, duration of symptoms, visual acuity, and clinical features on fundus examination, color fundus photographs, and fundus autofluorescence images were recorded. Electrophysiological tests, including pattern, focal, and fullfield electroretinogram (ERG), electro-oculogram, and colorcontrast sensitivity measurement, were also performed. Results: Based on electrophysiological attributes (ERG), patients with SMD-FFM could be classified into 3 groups. In group 1, there was severe pattern ERG abnormality with normal scotopic and full-field ERGs. In group 2, there was additional loss of photopic function, and in group 3, there was loss of both photopic and scotopic function. Differences in scotopic or photopic function among groups were not explained on the basis of differences in age of onset or duration of disease. Conclusions: Patients with SMD-FFM can be classified into 3 groups based on the absence or presence of generalized loss of either photopic or photopic and scotopic function. It appears that these 3 groups may represent distinct phenotypic subtypes in SMD-FFM.

Aims-Scanning laser polarimetry is a new technique allowing quantitative analysis of the retinal nerve fibre layer in vivo. This technique was employed to investigate the variation of the retinal nerve fibre layer thickness in a group of normal subjects of diVerent ages and ethnic groups. Methods-150 normal volunteers of different ages and ethnic groups were recruited for this study. Three consecutive 15 degree polarimetric maps were acquired for each subjects. Nerve fibre layer thickness measurements were obtained at 1.5 disc diameters from the optic nerve. Four 90 degree quadrants were identified. Results-The mean nerve fibre layer thickness varied from a minimum of 55.4 µm to a maximum of 105.3 µm, with a mean thickness value of 78.2 (SD 10.6) µm. Superior and inferior quadrants showed a comparatively thicker nerve fibre layer than nasal and temporal quadrants. Retinal nerve fibre layer thickness is inversely correlated with age (p < 0.001). White people showed thicker nerve fibre layers than Afro-Caribbeans (p = 0.002). Conclusion-The results indicate a progressive reduction of the nerve fibre layer thickness with increasing age. This may be due to a progressive loss of ganglion axons with age as suggested in postmortem studies. A racial diVerence in nerve fibre layer thickness is present between whites and Afro-Caribbeans. (Br J Ophthalmol 1997;81:350-354)

No abstract