Abstract
Purpose:
Quantification of the pupil response to chromatic light stimuli can be used to assess rod, cone, and melanopsin-containing ganglion cell activity. Here we developed a novel objective perimetry technique based on the pupil response to multifocal chromatic stimuli in normal subjects and in patients with glaucoma and retinitis pigmentosa (RP).
Methods:
A computerized infrared video pupillometer was used to record changes in pupil diameter in response to short- and long-wavelength stimuli (peak 485 nm and 620 nm, respectively) size V, at light intensities of 15-100 cd-s/m2 and duration of 1000 ms at different points of the visual field. The RP patient group included 16 eyes of 8 patients and the normal group included 18 eyes of 11 subjects. The glaucoma patient group included 22 eyes of 11 patients and the normal group included 38 eyes of 19 subjects.
Results:
Significantly reduced pupillary responses were obtained in RP patients under testing conditions that emphasized rod contribution (short-wavelength stimuli at 40 cd-s/m2) in nearly all perimetric locations (P <0.05). The glaucoma group showed significantly reduced pupillary responses under testing conditions that emphasized ganglion cell contribution (short-wavelength stimuli at high intensity) in all perimetric locations (P <0.05) as well as reduced pupillary responses under conditions that emphasized rod contribution mostly in nasal areas (p<0.05). By contrast, both patient groups demonstrated nearly normal pupillary responses under testing conditions that emphasized cone cell contribution (long-wavelength stimuli at high intensity) in majority of perimetric locations.
Conclusions:
This study demonstrates the feasibility of using pupillometer-based chromatic perimetry for objectively assessing visual field defects and retinal function in patients with retinal dystrophies and glaucoma. Furthermore, this method may be used to distinguish between the damaged cells underlying the visual field defect.
Keywords: 758 visual fields •
642 perimetry •
612 neuro-ophthalmology: diagnosis