Abstract
Purpose: :
To explore the use of multifocal pupillography in detecting functional changes associated with early age-related macular degeneration (AMD).
Methods: :
Pupillary contraction amplitudes and time to peak contractions of 19 early AMD eyes (mean age 69.6 ± 4.3) showing retinal drusen or irregular fundus pigmentation with mildly decreased visual acuity were examined and compared with 28 normal (mean age 68.5 ± 7.9) subjects with 3 different stimulus protocols. Stimuli were presented dichoptically and both pupil responses were measured concurrently. All protocols presented multifocal stimulus arrays subtending ±15° of visual field. A dart board layout having 44 independent test regions/eye with a mean presentation interval of 4 s/region and a duration of 33 ms on each presentation was employed. One protocol with peak test luminance of 288 cd/m2 employed a luminance balancing strategy designed to make responses more even across the visual field [ARVO (2009) E-Abstract 5281]. The non-balanced protocols had peak test luminance’s of 210 cd/m2 and 288 cd/m2 with a background 10 cd/m2. Test duration was 4 minutes separated into 8 segments of 30 second recording intervals. Cameras under infrared illumination monitored pupil responses. Data during blinks and fixation losses were excluded to a maximum of 15% of responses beyond which a segment was repeated.
Results: :
Unbalanced stimuli with a peak luminance of 210 cd/m2 achieved the largest decrease in mean response amplitude of -2.22 dB (t = 14.82, p <.00001); however this was found to be the least diagnostic. Balanced stimuli produced the largest delay in time to peak of 61.9 ms (t = 14.87, p <.00001). A linear discriminant model incorporating contraction amplitude and time to peak found the balanced protocol to be the most diagnostic achieving an AUC of 94.05%.
Conclusions: :
Clinical signs of early AMD produced significant abnormality in amplitude and latency of pupillary responses. Balancing stimuli to reduce the effects of response saturation produced ROC AUC of 94%, suggesting that multifocal pupillography is a sensitive tool in detecting early macular abnormalities in AMD.
Keywords: age-related macular degeneration • pupillary reflex • perimetry