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Perimetric assessment of a blind zone margin at the extreme periphery of human temporal retina

© 2017 A. V. Belokopytov, G. I. Rozhkova

Institute for Information Transmission Problems RAS (Kharkevich Institute) 127051 Moscow, B. Karetny per.19, Build. 1

Received 15 Aug 2016

In order to assess a blind zone margin at the extreme periphery of the temporal half of human retina, comparative evaluation of the temporal and nasal margins of the visual eld was performed in 16 subjects for several directions of gaze. The margins were estimated by means of a standard perimeter. The test stimulus was a LED producing a light spot ickering with frequency 2 Hz. The measurements were carried out for each eye in conditions of gaze xation on the center of perimeter arc (0°) and on the points shifted temporally by 15–30° to eliminate the occlusion of the nasal visual eld periphery by the nose usually taking place in standard clinical measurements with 0° direction of gaze. In the standard measurement conditions, the temporal and nasal margins varied among our subjects in the ranges 78–109° and 57–70° respectively. In about half of the subjects, no extension of the nasal eld had been found when the xation point was shifted temporally, indicating that the size of the blind zone corresponded to the di erence of the temporal and nasal clinical visual elds. However, in 6 subjects, a reliable increase of the nasal visual eld by 5–15° has been revealed manifesting that not the whole part of the temporal retina shielded by nose is blind. The data obtained indicate the plausibility of an old hypothesis (Brændstrup, 1948) implying that, at least partially, blindness of the extreme temporal retina periphery could be considered as a deprivation amblyopia developed due to the occlusion.

Key words: nasal visual eld, peripheral blind retina, individual variability, amblyopia

Cite: Belokopytov A. V., Rozhkova G. I. Perimetricheskaya otsenka granitsy slepoi zony na krainei periferii temporalnoi setchatki [Perimetric assessment of a blind zone margin at the extreme periphery of human temporal retina]. Sensornye sistemy [Sensory systems]. 2017. V. 31(1). P. 22-30 (in Russian).

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