Macula Dysfunction in Subretinal Neovascular Membranes Results in Significant Pupillary Escape

Abstract

Abstract: : Purpose: To assess whether macula dysfunction in subretinal neovascular membranes (SRNs) is associated with the phenomenon of pupillary escape by comparing healthy eyes with those with SRNs. Methods: Dynamic binocular infrared pupillometry of 20 eyes with unilateral SRNs and healthy fellow eyes. Full–field achromatic stimuli (22 x 14 deg) were presented to each eye alternately at 7 intensities within a range of 1–2 log cd.m^–2 for 1100 ms. Recordings were undertaken after 20 minutes of dark adaptation. Etiology of SRN was age–related macular degeneration (n=7), inflammatory (n=2) and infective (n=1). Results: Inter–eye comparison of pupillary responses showed all eyes with subretinal membranes to have a reduction in sustained contraction compared with the phasic component (by comparison of the time course and gradients of the dilation phases). This difference was statistically significant (p<0.05). Small subfoveal scars were also associated with this phenomenon. Conclusions: Inter–eye comparison of pupillary escape can be used to differentiate normal eyes from those with significant retinal pathology in the form of subretinal membranes. This observation confirms more limited previous reports of pupillary escape with subretinal membranes (Bergamin O, Kardon RH. Ophthalmology 2002;109:771–80). Further, the results show that pupillary escape is also a manifestation of small, purely subfoveal membranes, suggesting that photoreceptors and neurones subserving foveal function contribute a major component to the sustained pupil response. Finally, they show that pupillary escape can be detected using relatively shorter stimulus durations than in most previous investigations. The distinct changes in the pupil waveform suggest potential for clinical application of dynamic pupillometry for diagnosis of significant macula pathology in cases of ocular media opacities, where most other investigative tools are rendered ineffective.

Keywords: retinal connections, networks, circuitry • pupillary reflex • retinal neovascularization