Apparent accommodation and corneal wavefront aberration in pseudophakic eyes.
OBJECTIVE
To assess the relationship between apparent accommodation in pseudophakic eyes, multifocal corneal effects, and wavefront aberrations of the cornea.


METHODS
In 102 eyes of 86 patients who had undergone phacoemulsification and posterior chamber intraocular lens implantation, the amount of apparent accommodation was measured with an accommodometer. The degree of corneal multifocality was determined on the corneal topography by measuring the maximum and minimum corneal refractive powers within the pupillary area. Wavefront aberrations of the cornea were calculated by expanding the height data of the corneal topography into Zernike polynomials for individual pupil size. The influence of higher-order aberration on the retinal image quality was simulated by computing the point-spread function (PSF) and modulation-transfer function (MTF) from the aberration function.


RESULTS
There was a significant positive correlation between the amount of apparent accommodation and corneal multifocality (Pearson correlation coefficient, r = 0.451, P < 0.001). The coma-like aberration showed a significant positive correlation with the amount of apparent accommodation (r = 0.440, P < 0.001), but the spherical-like aberration did not (r = 0.001, P = 0.993). Among the coma-like aberrations, the component representing vertically asymmetrical distribution of corneal refractive power with greater refraction located in the lower part of the eye was most relevant to apparent accommodation. Computer simulation of PSF and MTF indicated that a focus shift of 0.5 D deteriorated the retinal image significantly more in eyes without higher-order aberrations than in eyes with a moderate amount of coma-like aberrations.


CONCLUSIONS
Coma-like aberration of the cornea, along with corneal multifocality, contributes to apparent accommodation in pseudophakic eyes.
Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan. toshika@md.tsukuba.ac.jp
Tetsuro
T
Oshika
Tatsuya
T
Mimura
Sumiyoshi
S
Tanaka
Shiro
S
Amano
Makoto
M
Fukuyama
Fumiaki
F
Yoshitomi
Naoyuki
N
Maeda
Takashi
T
Fujikado
Yoko
Y
Hirohara
Toshifumi
T
Mihashi
D000065:Accommodation, Ocular / Q000502:physiology*; D000180:Acrylic Resins; D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000502:physiology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D019904:Polymethyl Methacrylate; D019591:Pseudophakia / Q000503:physiopathology*
D000180:Acrylic Resins; D019904:Polymethyl Methacrylate