Eyes with geographic atrophy may display wedge-shaped band in outer plexiform layer

A hyporeflective, wedge-shaped structure often may be observed within the boundaries of the outer plexiform layer in patients with geographic atrophy secondary to age-related macular degeneration, a study showed.

The prospective, longitudinal, follow-up study included 71 consecutive patients aged 50 years or older who were examined between January 2010 and June 2011. Evaluations involved use of 35° fundus photography, fundus autofluorescence, spectral-domain optical coherence tomography and infrared imaging techniques.

The wedge-shaped band was observed in 72.9% of eyes, with its base on Bruch’s membrane and its top pointing toward the inner limit of the outer plexiform layer adjacent to the fringe between the atrophied area and the preserved retina. This structure is likely caused by expansion of the outer plexiform layer secondary to widening of Henle’s fiber layer, which probably relates to axonal swelling or interaxonal edema, according to the study authors.

“This effect is particularly relevant for understanding the association between the [retinal pigment epithelium] and photoreceptor cells, the timing of death (and, therefore, rescue) of remaining photoreceptor cells, and accurate measurement of the effects of interventions aimed to support the survival of photoreceptor cells,” they said.

Spectral-domain OCT enabled clear differentiation of limits between the outer plexiform layer and Henle’s fiber layer, making it useful for further investigation. However, the authors noted that their hypotheses must be confirmed by more sensitive techniques, such as in vivo adaptive optics scanning laser ophthalmoscope.