Accuracy of Intraocular Lens Power in Cataract Patients Underwent Excimer Laser PRK

We retrospectively evaluated postoperative refraction of four patients(five eyes)who received intraocular lens implantation after excimer laser photorefractive keratectomy (PRK).The mean age of the patients was 44.8 years and 3 patients were female and 1 patient was male.The mean interval between PRK and cataract operation was 20.2 months (1 to 45 months)and the mean follow-up time after cataract operation was 16.2 months(2~43months).Phacoemulsification and PMMA-PCL(6.0~6.5 mm)implantation were made in all cases.SRK-II formula,the most popular empirical formula was used in first 3 cases(group I),but Idem-lens formula,a primitive theoretical formula was used in another 2 cases (group II)after occurrence postoperative refraction errors in group I .In group I and II,the mean postoperative refraction error was +3.00 diopters and +0.50 diopters and uncorrected visual acuity at postoperative 2 months was 20/60 and 20/24 respectively.The mean of calculated IOL-power was -3.75 diopter in group I and -0.625 diopter in group II.From these results,the empirical formula is definitely unsuitable for the calculation of IOL power in the cataract operation following excimer laser PRK. Moreover,although a primitive one,Idem-lens theory could be temporally useful for the IOL-power calculation in such cases.In conclusion,new formula is required for the cataract operation following excimer laser PRK.

Evaluation for the Accuracy of the SRK/T Formula in PCL Implanted Patients(I)

The 1224 cataractous patients who had extracapsular cataract extraction and posterior chamber lens implantations were evaluated retrospectively irrespective of style, postoperative position of intraocular lens and surgeon. The 100 cataractous patients who had extracapsular cataract extraction and posterior chamber lens implantations in the bag accurately using single lens style by one surgeon(E.H.L) were evaluated prospectively. And then the predictive accuracy of the SRK/T intraocular lens power calculation formula was compared with other formulas (SRK, SRKII and Holladay) without consideration of individual A constant. The SRK/T formula was more accurate than other 3 formulas in all axial length, but there were no significant differences statistically. Especially for short and long eyes, SRK/T formula was more accurate than other 3 formulas.