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PICTURE SIMULATION OF CONTRAST SENSITIVITY IN ORGANIC AND FUNCTIONAL AMBLYOPIA
Author(s) -
LUNDH BJÖRN L,
DEREFELDT GUNILLA,
NYBERG STEN,
LENNERSTRAND GUNNAR
Publication year - 1981
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.1981.tb08745.x
Subject(s) - contrast (vision) , optic nerve , lesion , spatial frequency , sensitivity (control systems) , visual acuity , pixel , medicine , audiology , ophthalmology , optometry , artificial intelligence , optics , computer science , physics , surgery , electronic engineering , engineering
We have tried to illustrate some contrast sensitivity defects by picture simulation. We have used data obtained from 2 patients: a woman with optic nerve lesion (Snellen VA 0.5) and a 7.5‐year‐old boy with anisometropic amblyopia (VA 0.6). The optic nerve lesion was represented by profound contrast sensitivity loss for all spatial frequencies, while the anisometropic eye showed loss only at high spatial frequencies. A positive picture was decomposed into 1.25 × 10 6 pixels (picture elements), using a drum scanner. In a computer each spatial frequency component of the picture was multiplied by the ratio between the patient sensitivity value and that of an age‐matched reference group and a modified image was processed. The pictures illustrate the poor image quality that is associated with general contrast sensitivity loss, even when Snellen visual acuity is only moderately impaired.