J Korean Ophthalmol Soc.  1999 Feb;40(2):346-353.

Difference of the Accuracy between Autorefration and Subjective Refraction in Photorefractive Keratectomy(PRK) and LASIK-Treated Eyes

• Lee JB
• Lee KS
• Lee DH
• Kim EK

Abstract

Authors decided to test whether differences occurred in automated and subjective refraction in untreated, PRK, and LASIK-treated eyes. Ninety six eyes of 50 patients(96 eyes) who underwent PRK(57 eyes) or LASIK(39 eyes) for myopia and myopic astigmatism were routinely autorefracted with the CANON RK-3 before subjective refraction was done, using several parameters. This two procedures were done preoperation and 3 months after operation. In comparing the postoperative(PRK, LASIK) results, automated refraction showed more myopia and higher cylinder power, without significant difference in refractive axis, than those of subjective measurement. The difference of cylinder power were found in the cases of large ablation depth(above 100micrometer), high degree of eccentric ablation(above 0.25 mm), LASIK operation. The significant differences of cylinder power and axis were found in the cases of high degree of eccentric ablation(above 0.25 mm). So we recommend the method of subjective refraction before PRK and LASIK operation instead of using automated refraction. Postoperatvely, we also should evaluate the postoperative status of the patient by subjective refraction. And we should decide the amount of ablation in case of retreatment by subjective refraction, instead of autorefraction. We have to be cautious of evaluating the automated refraction results after operation, especially in cases of large ablation depth, high degree of eccentric ablation, and LASIK.

Keyword

Automated refraction; PRK; LASIK; Subjective refraction

MeSH Terms

Astigmatism
Axis, Cervical Vertebra
Humans
Keratomileusis, Laser In Situ
Myopia
Retreatment