Heterogeneity of Fundus Autofluorescence in Stargardt Macular Dystrophy

Abstract

 

Purpose:

 

To study the fundus appearance of three siblings with the same Stargardt macular dystrophy ABCA4 mutation using various imaging techniques .

 

Methods:

 

A family of three siblings, aged 34, 32, and 29, diagnosed at ages 11, 9, and 9, respectively, and with the same ABCA4 mutation was studied using autofluorescence (AF), color photography, optical coherence tomography (OCT), and fluorescein angiography (FA). Lesion size was measured using the NIH software ImageJ. Central retinal thickness from OCT was measured using onscreen calipers.

 

Results:

 

With color fundus photography, all 3 siblings were seen to have atrophic retinal lesions and flecks consistent with Stargardt macular dystrophy. Table 1 summarizes the results of the total area of retinal pigment epithelium (RPE) atrophy measured on color photography and AF as well as retinal thickness measured by OCT. FA images were obtained of patient 1 with measured lesion areas 19.4 mm² (right) and 18.3 mm² (left). Lesion distribution varied from single, large lesions to small lesions with multiple satellites and confluent foci. Autofluorescence clearly demonstrated areas of atrophic RPE as regions of decreased fluorescence, with mottled areas of increased and decreased fluorescence corresponding to the flecks. Although the lesion patterns in AF images resembled those in the corresponding color images, areas of RPE atrophy in AF were generally larger than those in the color images. Nonetheless, the differences between the AF images and color photos were small, ranging from 0 to 2.1 mm² (1.1 ± 0.9 mm²). For patient 1, measured lesion size in FA images was larger than in color and AF, though the lesion patterns were similar. All OCT images showed outer retinal atrophy and loss of foveal contour. Central retinal thickness ranged from 24 - 105 µm.

 

Conclusions:

 

A surprising degree of heterogeneity was demonstrated in fundus imaging of these 3 siblings with the same ABCA4 mutation. Autofluorescence sharply delineates areas of abnormal RPE better when compared to fundus photography, but the total lesion areas and patterns of distribution are similar. Central retinal thickness in these patients was quite thin, indicating advanced disease.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retinal degenerations: hereditary • macula/fovea