Characteristics of preoperative ocular biometric parameters related to refractive error after age-related cataract surgery

Abstract

Objective To investigate the distribution of refractive errors (RE) after age-related cataract surgery and the potential preoperative ocular biometric parameters that may influence RE. Methods A retrospective study that included 197 age-related cataract patients (197 eyes) was carried out. Anterior chamber depth (ACD) , anterior chamber volume, horizontal corneal diameter (white-to-white, WTW) , and corneal spherical aberrations were measured by a Pentacam, then the WTW/ACD ratio was calculated. Corneal power (mean K value) and axial length were measured by an IOLMaster, and postoperative refraction was predicted by an SRK-T formula. Subjective refraction was examined 3 months after cataract surgery, and the difference between the predicted value and subjective refraction was calculated as RE. Single factor and multiple linear regression analyses were performed to study the relationship between RE and the preoperative biometric parameters. Patients were divided into a hyperopic or myopic error group, based on an RE larger than +0.50 D or less than -0.50 D, respectively. Independent t tests were performed to compare the differences in biometric parameters between the two groups. Results The mean RE after the surgeries was -0.50±0.92 D, including 88 cases of myopic error (44.7%) and 28 cases of hyperopic error (14.2%) , with mean REs of -1.31±0.60 D and +0.86±0.29 D, respectively. Single-factor regression analyses showed both WTW (β=0.473, F=12.49, P<0.01) and ACD (β=0.286, F=4.57, P<0.05) could significantly influence postoperative RE, while the influence of WTW/ACD was close to significance (β=-0.121, F=3.59, P=0.06). Multiple linear regression showed only WTW entered the final model (F=12.49, P<0.01). A significant difference in mean WTW/ACD ratios was noticed between the myopic (4.91±1.20) and hyperopic (4.48±0.65) error groups (t=2.42, P<0.05). Conclusion Preoperative ACD and WTW can influence postoperative refractive error in age-related cataract patients. The WTW/ACD ratio can be considered as a morphological indicator to describe the anterior chamber, which may be useful to predict RE after cataract surgery. Key words: Cataract; Refraction; Anterior chamber depth; Corneal diameter