NOVEL TECHNIQUE: CHROMATIC MULTIFOCAL PUPILLOMETER FOR OBJECTIVE EVALUATING 76-POINT CENTRAL 30 DEGREE PERIMETRY

Abstract

 

Purpose

 

We recently demonstrated the feasibility of quantifying pupil responses to multifocal chromatic light stimuli for objectively assessing visual field defects in retinal dystrophy and Glaucoma patients. Here we assessed a second-generation chromatic multifocal pupillometer device with 76 LEDs of 30 degree visual field and a smaller spot size aimed of achieving better perimetric resolution.

 

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) presented by 76 LEDs, 1.8mm spot size, at increasing light intensities of 10-500 cd/m2 and duration of 1-3 sec at different points of the 30 degree visual field. The pupil response of 10 normal subjects was tested as well as the response of 9 retinitis pigmentosa patients

 

Results

 

The pupillary contraction of normal subjects reached 20% in response to low intensity (10cd/m2) short wavelength stimulus. For the long wavelength stimulus a significantly higher intensity was required (140 cd/m2) to reach a pupillary contraction of 20%. A sustained pupil contraction characteristic of melanopsin-driven pupil response was observed when blue light stimulus duration was increased to 3 second and stimulus intensity was increased to 500cd/m2. Significantly reduced pupillary responses were obtained in retinitis pigmentosa patients under testing conditions that emphasized rod contribution (short-wavelength stimuli at 40 cd-s/m2) in nearly all perimetric locations. By contrast, the patients demonstrated nearly normal pupillary responses under testing conditions that emphasized cone cell contribution (long-wavelength stimuli at high intensity) in majority of perimetric locations, especially central locations.

 

Conclusions

 

The new device enables objective determination of visual field at higher resolution with minimal need for patient cooperation. The health of cones, rods and melanosopic ganglion cell pathways can be evaluated using the pupil light reflex to 1.8 mm spot stimulus.

 

 

Second-generation prototype: fast acquisition of 76-point objective chromatic 30 degree visual field.

 

Keywords: 758 visual fields • 612 neuro-ophthalmology: diagnosis • 550 imaging/image analysis: clinical