Preoperative assessment
LASIK, IOL, LRI, diopter
AFTER CATARACT, IOL, BILATERAL CATARACTS
Preoperative tests were performed for each eye. Potential Visual Acuity was assessed, and the surgeon estimated the patient’s potential acuity. The patient was expected to be capable of achieving better than 20/40 (0.5) (Snellen) best corrected distance vision after cataract extraction and IOL implantation. Monocular uncorrected distance visual acuity (UDVA) was measured using a standard acuity chart. Preoperative manifest refraction was required. BCDVA was measured using a standard acuity chart. Patients required having clinically significant bilateral cataracts in both eyes. Both photopic undilated and pharmacologically dilated pupil size were measured to the nearest one-half millimetre using a pupillometer, pupil gauge card or millimetre rule.Contact lenses were not to be worn for at least one month prior to the preoperative visit for PMMA lenses, two weeks for gas permeable lenses, and one week for extended-wear and daily-wear soft contact lenses. Corneal stability was verified for any subject who wore PMMA lenses within five years or any other type of contact lenses within six months prior to the preoperative visit. To verify stability, the keratometric measurements were repeated at least one week after the initial preoperative baseline keratometric measurement. Corneal curvature was considered stable if the difference in keratometric cylinder (vertical versus horizontal keratometric readings) between the two time points was no more than 0.50 diopter. Additionally, the difference between the two horizontal readings as well as the difference between the two vertical readings should have been no more than 0.50 diopter. Changes in keratometric axis was no more than ± 15°. Axial length was taken to determine the appropriate spherical IOL power using an A-constant. The spherical IOL power was calculated according to the patients preferred target refraction using optimized constants when available, and an appropriate IOL power calculation formula depending on the axial length.No additional refractive procedure was performed on any of the study eyes at the time of the initial surgeries or during the postoperative study period (e.g., limbal relaxing incision (LRI), opposite clear corneal incisions (OCCI), photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK)).