Effect of Preoperative Corneal Symmetricity on Clinical Results in Myopic Excimer Laser PRK.

Lym, Seog Bum; Joo, Choun Ki; Kim, Jae Ho

Original Article

Journal of the Korean Ophthalmological Society 1996;37(8):1342-1348.
Published online August 1, 1996.

Effect of Preoperative Corneal Symmetricity on Clinical Results in Myopic Excimer Laser PRK.

Seog Bum Lym, Choun Ki Joo, Jae Ho Kim

Department of Ophthalmology, KangNam St. Mary's Hospital, Catholic University, Medical College, Seoul, Korea.

엑시머레이저 근시교정술에서 술전 각막의 대칭성이 시력예후에 미치는 영향

임석범(Seog Bum Lym),주천기(Choun Ki Joo)

Abstract

We compared postoperative visual outcome and corneal refractive power depending on preoperative corneal topographic pattern and the predictibility of corneal topographic measurement compared with keratometric measurement after PRK. The subjects were 91 eyes divided into two goups composed of 44 eyes, symmetric bow tie type(SB) and 47 eyes, asymmetric bow tie type (aSB). The visual acuity, central power, and topographic pattern were measured before operation, postoperative 1 week, 1, 2 and 6 month in two groups, but no statistical difference(p>0.05). The averages of uncorrected visual acuity at 6 month were improved to 0.80(SB) and 0.85(aSB) from 0.09(SB) and 0.11(aSB) before operation. Topographic central refractive powers of +42.98D (SB), +43.32D(aSB) before operation were changed to +37.68D(SB), 37.56D(aSB) at 6month. The pattern of the region affected by the excimer laser was classified by key hole type 38%(SB) , 34%(aSB) , uniform roud type 41%(SB), 43%(aSB), semicircular type 21%(SB), 23%(aSB). The proportion of the difference less than one diopter between PRK setting and the change of the corneal refractive power at 6month was 36% and 76% in keratometric and topographic measurement. Above results show that the asymmetricity of bow tie type did not influence the visual outcome. The topographic measurement was better than keratometric measurement in evaluating the corneal refractory change after PRK.

Key Words: Asymmetric bow tie type;Key hole type;Semicircular type;Symmetric bow tie type;Uniform round type