[Assessing retinal photosensitivity in patients with central vision impairment using a portable perimeter (a...

The problem of reliably performing perimetry in people with impaired central vision who are unable to keep the gaze on the fixation point during the examination is yet to be resolved.

To develop a perimetry method for patients with impaired central vision using a portative perimeter based on a virtual reality device (p-VRD).

The study included 16 eyes (19 patients) without central vision (maximum visual acuity was from lateral light projection to 20/400). Each eye was examined in 3 ways and 3 groups were organized: 1^st (control) - automatic static perimeter; 2^nd (control) - Goldmann kinetic perimeter; 3-rd (experimental) - portable automatic static perimeter based on a virtual reality device (p-VRD). Patients of the experimental group used their sense of deep proprioception to keep the gaze on the screen center: putting p-VRD on, they were asked to lift a finger opposite their face on the eye level so that their line of sight went through the centre of the device's screen.

Perimetry results in the 1^st group were found to be unreliable due to frequent fixation loss. The contours of central scotoma could be determined in perimetry results of the 2^nd and 3^rd groups while achieving good comparability between the two respective methods (conformity coefficient K=73.7%).

It is possible to assess light sensitivity of the eyes without central vision by performing perimetry with p-VRD. Satisfactory gaze fixation on the central zone of p-VRD screen is possible thanks to the human's sense of deep proprioception - the nonvisual sense of the exact location of the limbs.