Subretinal membranes are associated with abnormal degrees of pupil “evasion”: an index of clinical macular dysfunction

• Published in: British journal of ophthalmology 2006-09, Vol.90 (9), p.1115-1118
• Main Authors: Zaidi, F H, Bremner, F D, Gregory-Evans, K, Cocker, K D, Moseley, M J
• Format: Article
• Language: English
• Subjects: Adaptation; Adult; age related maculopathy; Aged; Aged, 80 and over; ARM; Biological and medical sciences; Clinical Science - Scientific Report; Confidence intervals; Diagnostic Techniques, Ophthalmological; Female; FFA; fundus fluorescein angiography; Humans; Light; Macular Degeneration - diagnosis; Macular Degeneration - etiology; Macular Degeneration - physiopathology; Male; MDA; Medical sciences; Membranes; mid-dilation amplitude; Middle Aged; Miscellaneous; neovascular membrane; Ophthalmology; PDT; PEVR; Photic Stimulation - methods; photodynamic therapy; Pupil - physiology; pupil escape; pupil evasion; pupil evasion ratio; pupil index; RAPD; reflex amplitude; Reflex, Pupillary; relative afferent pupillary defect; Retinal Neovascularization - complications; Retinal Neovascularization - physiopathology; SRNs; subretinal membrane; subretinal neovascular membranes
• ISSN: 0007-1161; 1468-2079
• DOI: 10.1136/bjo.2005.083279

Aim: To assess whether macular dysfunction caused by unilateral subretinal neovascular membranes (SRNs) is associated with pupil “evasion” (that is, increased initial rate of re-dilation following a brief light stimulus). Methods: Comparative observational series. 20 eyes of 10 participants, all with unilateral SRNs and healthy fellow eyes. Dynamic infrared pupillography at seven stimulus intensities (duration 1100 ms, intensities over 2 log unit range). Pupil evasion ratio (PEVR; defined as the ratio of light response amplitude to amount of recovery at the mid-time point of re-dilation expressed as a percentage) was calculated for each stimulus intensity (mean of five recordings). Results: Inter-eye PEVR is significantly reduced in eyes with SRN (that is, greater pupil evasion in SRN eyes: range p  =  0.002 to p  =  0.05 (paired t test)) and is most apparent at higher stimulus intensities. Conclusions: PEVR is a novel parameter that is analogous to the pupil escape ratio, but measured following a short rather than a sustained light stimulus. PEVR is significantly altered by macular disease. Clinically PEVR may be used to detect occult unilateral or asymmetric maculopathy in situations such as ocular media opacities like cataract, when pupil reactions are unaffected or augmented, while other tests of retinal function are diminished. PEVR represents altered neuronal firing in cones and macular ganglion cells.