Photoreceptor Abnormalities in Intermediate Age-Related Macular Degeneration

Abstract

 

Purpose

 

To investigate the relationship between photoreceptor layers overlying and adjacent to large drusen in intermediate non-neovascular age-related macular degeneration (AMD).

 

Methods

 

Patients with AMD (n=41; ages 53-83 years) and elderly control subjects without eye disease (n=10; ages 51-79) were studied with SD-OCT (spectral-domain optical coherence tomography). Characteristics of large drusen (>125 µm) were measured and thickness of photoreceptor laminae overlying drusen and in retinal regions neighboring the drusen were quantified.

 

Results

 

There were 750 large drusen in 63 AMD eyes studied. The width of drusen sampled averaged 352 (SD=153) µm and height averaged 78 (SD=31) µm. There was significant reduction of the photoreceptor outer nuclear layer (ONL) thickness overlying 92% of the drusen. The thickness of the layer corresponding to photoreceptor inner and outer segments above drusen was also reduced, and the reduction was proportional to ONL thickness. At ~20% of normally laminated paradrusen locations sampled within ~300 µm of peak drusen height, ONL thickness was significantly increased compared to age- and retinal-location-matched normal values. Topographical analyses of the macula showed ONL thickening occurring in paradrusen regions as well as retinal locations distant from drusen.

 

Conclusions

 

Reductions in the photoreceptor laminae overlying drusen were detectable and this is consistent with histological studies revealing neuronal degeneration in AMD. ONL thickening in some macular areas of AMD eyes has not been previously reported and may be an early phenotypic marker of photoreceptor stress, as has been proposed for this finding in hereditary retinal degenerations.

 

Keywords: 504 drusen • 550 imaging/image analysis: clinical • 648 photoreceptors