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Optimal refraction with monofocal intraocular lenses: no beneficial effect of astigmatism
Author(s) -
Naeser Kristian,
Hjortdal Jesper
Publication year - 2011
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.1755-3768.2009.01650.x
Subject(s) - fixation (population genetics) , intraocular lenses , pseudophakia , mathematics , astigmatism , optics , ophthalmology , intraocular lens , refraction , physics , medicine , population , environmental health
. Purpose: This study aimed to determine the optimal spherocylindrical refraction in the monofocal, pseudophakic eye using power vectors in dioptric space. Methods: For parallel incident light the defocus of a spherocylinder may be described in dioptric space as:where SEP = spherical equivalent power in dioptres (D) and M = astigmatic magnitude in D. In the pseudophakic eye the defocus for any fixation distance x is:The cumulative defocus over a fixation interval is the integral of D (SEP, M , x ) . A minimal value for cumulative defocus will indicate a maximal unaided visual acuity (VA) over the chosen fixation interval. We calculated the summated defocus for various spherocylinders for fixation distances ranging from 0.5 m to 6.0 m. Results: Minimal cumulative defocus was present for pure spheres of − 0.25 D to − 0.5 D. No beneficial effect of the presence of astigmatism was detected. Conclusions: In monofocal pseudophakia the highest possible VAs over the most extended fixation ranges may be achieved with slight myopic refractions without astigmatic components.