Refractive Outcome and Influencing Factors of Postoperative Refraction in Cataract Surgery
Authors: Meiers Dairis , Kursīte Anete , Laganovska Guna 
Published: September 2018

Abstract
Introduction. Phacoemulsification with intraocular lens implantation provide high visual acuity after procedure, increasing quality of life and vision. The aim of procedure is to gain a target refraction, in most cases emmetropia, when a patient does not need visual correction for a distant sight (1). Although the preoperative evaluation and surgery technique has developed in the last years, it is not possible to gain the target refraction in all cases. There still are patients with high postoperative error, which means that there are influencing factors that should be identified. Aim of the Study. Aim of the study was to evaluate the refractive outcome three months after cataract surgery in Pauls Stradins Clinical University Hospital and to find out the factors that influence postoperative refraction after cataract surgery. Material and methods. Retrospective study included 43 eyes of 38 patients who underwent phacoemulsification’s cataract surgery with intraocular lens implantation and fixed A constant. Surgeries were done at PSCUH from August, 2017 till January, 2018. Data were collected at postoperative follow-up three months after surgery (postoperative refraction). The difference between data intervals was evaluated using nonparametric tests - Mann-Whitney tests. The correlations between postoperative refraction and potentially influencing factors of refractive outcome were evaluated by nonparametric correlation tests - Spearman’s rho test. Results. Of the patients enrolled in the study, whose median age was 75 years (IQR = 78-68 years), 20,9 % (n=9) were men, 51,2% (n=22) had no comorbidities, 34,9% (n=15) had one comorbidity, but two comorbidities had 14% (n=6) patients. At the time of cataract surgery 16,3% (n=7) of patients had Diabetes mellitus, but 46,5 % (n=20) had Glaucoma. The absolute error between target refraction and postoperative refraction for all cases was 0.48 ± 0.41 D (mean + standard deviation). The main aim of surgery - emmetropic eye - was achieved in 30,2 percent of cases (n=13). In the study, 69.8 percent of cases (n=30) were within ±0.50 D difference between target and final postoperative refraction, and 90.7 percent of cases (n=39) were within ±1.00 D. The study showed moderate and negative correlation between the axial length of eye and refractive outcome of cataract surgery: correlation coefficient r= -0.412 (p=0.006). The study showed week correlation between the age of patients and refractive outcome of cataract surgery r=0.091 (p=0.562). The difference between IOL power calculated using Haigis formula and IOL power of lens implanted during surgery also had a week correlation with refractive outcome r=0.033 (p=0.833). Correlations between comorbidities and refractive outcome were week and negative - in case of diabetes mellitus r= -0.127 but in case of glaucoma r= -0.13. Conclusions. Cataract surgery outcome showed high quality of this procedure because of the insignificant mean postoperative refractive error. The study did not show statistically significant correlation between refractive outcome and the age of patients, presence of diabetes mellitus or glaucoma and the difference between calculated and implanted IOL power. The study revealed moderate and negative correlation between the axial length and refractive outcome. This correlation coincides with the results of the studies previously made. The refractive outcome is worse for smaller eyes.