ABSTRACT
To compare the accuracy of Sanders-Retzlaff-Kraff II [SRK II] and 3[rd] and 4[th] generation intraocular lens [IOL] formulas and to compare the effect of different anterior chamber depths among the IOL formulas in cataract patients with normal axial length [AL; 22.0-24.5 millimeters, mm]. A retrospective chart review was performed of patients with normal AL who underwent cataract surgery. The SRK II and 3[rd] generation IOL formulas [Hoffer Q, SRK T, Holladay l] were compared to the 4[th] generation Haigis formula. For analysis, preoperative anterior chamber depth [ACD] was divided into three subgroups- =/<3, 3-3.5, and >/= 3.5 mm. The mean error [ME] and mean absolute error [MAE] of each formula was compared for each subgroup against the total. The difference between the ME and MAE of the formulas were compared for each ACD subgroup. P< 0.05 was considered statistically significant. The study sample was comprised of 309 eyes. The MAE were 0.56 D, 0.52 D, 0.51 D, 0.50 D, and 0.50 D with Haigis, Hoffer Q, SRK T, Holladay 1, and SRK II formulas, respectively The Haigis formula was a significantly weaker predictor than the SRK T [P < 0.00l] and Holladay 1[P= 0.035]formulas. The ME with Haigis formula was -0.23 D which changed to -0.06 D with ACD >/= 3.5 mm [P = 0.002]. The ME was -0.24 D with SRK II and changed to -0.09D with ACD 0.05, all comparisons]. The SRK II formula can predict refraction in patients with normal AL and ACD less than 3 mm with less error and is preferred over other formulas. The Haigis formula is the preferred choice in patients with a normal AL and ACD longer than 3.5 mm. The prediction accuracy of Hoffer Q, SRK T, and Holladay 1 is comparable in normal AL
ABSTRACT
To determine the association between refractive errors and different types of cataract in Tehran, Iran. In a cross-sectional survey with a stratified cluster sampling approach, refractive errors were tested under cycloplegia. Myopia and hyperopia were defined as a spherical equivalent refractive error <-0.5 diopters [D] and more than +0.5 D, respectively. Cataract was graded according to the Lens Opacities Classification System III classification and the association between refractive errors and cataract was assessed. Of 1434 participants over the age of 40 years who participated in the study, data from 1313 right eyes were analyzed. The mean age of the participants was 52.7 +/- 10.0 years, and 58.3% [n = 767] were female. Overall, myopia was more prevalent among those with cataract [odds ratio [OR]: 2.00, 95% confidence interval [CI]: 1.38-2.89]. Based on the type of cataract and refractive errors, the odds of myopia was significantly higher with nuclear cataracts [OR: 1.81, 95% CI: 1.14-2.87]. The odds of myopia was higher for cases of nuclear cataract with some degrees of posterior subcapsular cataract [PSC] [OR: 3.33, 95% CL 1.42-7.80]. Of nine participants with cortical cataract, seven participants had hyperopia [OR: 3.77, 95% CI: 0.78-18.31]. Individuals with nuclear and PSC showed a significantly higher prevalence of myopia while the prevalence of hyperopia was lower in those with cataract. High myopia was seen in higher grades of nuclear cataract. The high percentage of hyperopia was also significant in patients with cortical cataract. More studies are necessary to clarify the correlation between cortical cataract and hyperopia