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The significance of using different methods for analysing photokeratoscopic data
Author(s) -
Edmund Carsten
Publication year - 1986
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.1755-3768.1986.tb06880.x
Subject(s) - keratometer , dioptre , mathematics , radius of curvature , radius , constant (computer programming) , curvature , earth radius , mathematical analysis , geometry , statistics , optics , ophthalmology , physics , cornea , medicine , mean curvature , computer science , magnetosphere , computer security , plasma , visual acuity , mean curvature flow , quantum mechanics , programming language
With the photokeratoscope of Wesley‐Jessen, 45 pictures were taken from the right eye of 18 normal persons and analysed by 2 different methods. The first method is based on the assumption that radius of the corneal curvature is constant between 2 points of reflection, the second method is without such a preliminary assumption on the corneal contour. The parameters estimated: radius of the central curvature (K) and the coefficient of radius variation (RV) are compared. A difference in K at 1.5% corresponding in case to 0.6 diopters and a difference in RV at 46% are demonstrated. The differences are correlated to the error introduced by the assumption on constant radius. Further it is established that K measured by the keratometer of Javal‐Schiøtz is about 0.14 mm larger (in case 0.7 diopters) than K estimated by the method of photokeratoscopic data analysis without preliminary assumption.