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Quantification of prism induced metamorphopsia as a model for clinical retinal (and other) distortions
Author(s) -
Hirose Hiroshi,
Enoch Jay M.,
Tuan KuangMon
Publication year - 1997
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.1997.0_890.x
Subject(s) - metamorphopsia , prism , distortion (music) , optics , computer science , computer vision , artificial intelligence , physics , bandwidth (computing) , visual acuity , telecommunications , amplifier
Summary Metamorphopsia (all causes) results in perceived distortions in the visual field. A simple technique utilizing hyperacuity judgments was developed in this laboratory some years ago to allow quantification of such distortions. We ask here, how good is this assessment method at detecting a distortion? To control better investigations of metamorphopsia, a model providing constant optical distortions and resultant perceptual metamorphopsia was devised using plane prisms of 8Δ and 15Δ. The instrument includes a beam splitter and a CRT display controlled by an IBM PC computer and a‘mouse’. In this study, three short vertical lines (perpendicular to the prism base‐apex line) were used to assess image distortion in the central retinal area. Positions of individual lines of this pattern were varied in order to determine perceived distortions induced by a prism. Normal observers were tested on multiple occasions. It is possible to measure accurately prism‐induced directional biases (mean locations) using this method. We separated personal setting biases from the prism‐related distortions. The test method devised mimics modest clinical metamorphopsia. Prism magnitude affected settings. We were able to make judgements to less than ±2% error.