[Simulation of toric intraocular lens results: the effect of repeatability and increments of automated keratometry].
OBJECTIVE
To study the repeatability and scale increments of automated keratometry and their influence on the use of the toric intraocular lens (IOL) and on astigmatism correction.


METHODS
The study enrolled 131 eyes of 82 patients. Preoperative corneal astigmatism was measured in the different (0.01D and 0.25D) scale increment setting of automated keratometer on separate days. An arithmetic astigmatism in 0.25 D scale increment was also calculated from that of 0.01 D scale increment. These three types of corneal astigmatism were comparatively appraised with a web-based calculator, evaluating indication and style selection of the toric IOL and simulated residual astigmatism.


RESULTS
Different scale increments caused no significant difference in simulated residual astigmatism. The repeatability of calculated IOL style selection and axis location was low in eyes with mild astigmatism. True standard deviation of test-retest discrepancy in the size of corneal astigmatism was 0.293 D.


CONCLUSIONS
In mild astigmatism, the effectuation of the toric IOL, such as IOL style selection and axis location, was ineffective. However, the scale increment of 0.25 D presented moderate sensitivity. The refinement of corneal astigmatism measurement and development of algorithm would be the key to more accurate astigmatism correction with a toric IOL implantation.
Department of Ophthalmology, Yukioka Hospital, 2-2-3 Ukida, Kita-ku, Osaka 530-0021, Japan. yoshihikoninomiya@gmail.com
Yoshihiko
Y
Ninomiy
Yayoi
Y
Kanazawa
Yoshinao
Y
Kojima
Naoyuki
N
Maeda
D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000601:surgery*; D001331:Automation; D003315:Cornea / Q000601:surgery*; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular / Q000009:adverse effects*; D007910:Lenses, Intraocular / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D054140:Refractive Surgical Procedures; D016896:Treatment Outcome