The Study On The Relationship Between The Changes Of ACD And Refractive Errors After Cataract Surgery And The Calculation Of Intraocular Lens Diopter Of The Second Eyes

The accuracy of refraction after cataract surgery determines the postoperative visual effect.With the improvement of optical measurement methods on biological parameters of eyeball,minimally invasive surgical technologies and design of IOL,the refraction effect after cataract surgery has been improved significantly.However,a part of patients get relative large refractive errors after cataract surgery,resulting in unfavorable visual outcome.To evaluate the personalized IOL calculation method and improve postoperative visual quality,the refractive errors after cataract surgery will be primarily investigated in Tangdu Hospital.The relationship between the changes of central anterior chamber depth after cataract surgery and refractive errors will be analyzed.The prediction methods of postoperative central anterior chamber depth will be further explored,and the calculation of intraocular lens diopter of the second eye will be verified after sequential cataract surgery in this study.Objectives1.To evaluate the refractive errors after phacoemulsification and intraocular lens implantation through a retrospective analysis.2.To analyze the relationship between central anterior chamber depth changes and refractive errors after phacoemulsification and intraocular lens implantation by Pentacam HR system,and investigate the clinical value of the prediction formulas of postoperative anterior chamber depth.3.To verify the correlation between binocular refraction errors after sequential cataract surgery,and explore the individualized calculation method of intraocular lens during the second eye cataract surgery.Methods 1.Retrospective analysis of the refractive errors after cataract surgery Refractive outcomes at 1-2 days(426 eyes),2 weeks(371 eyes),1 month(322 eyes)and 3 months(156 eyes)after phacoemulsification combined with intraocular lens implantation were retrospectively analyzed.IOL Master was used to calculate intraocular lens diopter.All surgeries were performed by the same experienced surgeon and the intraocular lens were implanted into capsular bags.The postoperative refractive errors were analyzed by comparing the equivalent spherical of the postoperative refractive outcomes with the predicted postoperative refractive diopter.2.Study on the relationship between the changes of central anterior chamber depth and refractive errors after cataract surgery Effect of pupil dilation on anterior chamber depth Changes of central anterior chamber depth before and after pupil dilation in 25 eyes undergoing cataract surgery were observed.The central anterior chamber depth was respectively measured 1-2 days before and after surgery with Pentacam system in both conditions of normal pupils and dilated pupils.Relationship between the changes of central anterior chamber depth and refractive errors after cataract surgery Changes of central anterior chamber depth of patients with different refractive outcome after phacoemulsification combined with intraocular lens implantation were observed.Central anterior chamber depth and refractive outcomes 1-2 days before surgery and 1 month(123 eyes)after surgery were collected.Patients were divided into group A(CACD < 1.65mm)and group B(CACD ? 1.65mm).Central anterior chamber depth was measured with Pentacam system.The refraction diopter was measured by the computer and subjective optometry.Intraocular lens diopter was calculated with IOL Master.The relationship between the changes of central anterior chamber depth and postoperative refractive errors was analyzed.Prediction of the central anterior chamber depth after cataract surgery A total of 65 eyes of central anterior chamber depth and lens thickness before cataract surgery and the central anterior chamber depth one month after cataract surgery were analyzed.The central anterior chamber depth under normal pupil and lens thickness under pupil dilation were measured with Pentacam HR system.The correlations between the postoperative central anterior chamber depth with the preoperative central anterior chamber depth and lens thickness were analyzed and the prediction formulas of central anterior chamber depth after cataract surgery were explored.3.The correlations between binocular refractive errors after sequential cataract surgery and calculation of the intraocular lens in the second eyes cataract surgery The binocular refractive errors of 94 patients(188 eyes)after sequential cataract surgery were analyzed.Among them,34 patients(68 eyes)were included to adjust the intraocular lens diopter implanted in the second eyes.Intraocular lens diopter was calculated with IOL Master.The intraocular lens diopter of the second eyes were adjusted according to 50% of the refractive errors one month after the first eyes cataract surgery.The absolute refractive errors at one month after the second eyes cataract surgery were studied.Results 1.The status of the refractive error after cataract surgery The percentage of absolute refractive errors < 0.5D,0.5D-1.0D and ? 1.0D 1-2 days after cataract surgery were 56.4%,25.1% and 18.5%,respectively.The percentage of absolute refractive errors < 0.5D,0.5D-1.0D and ? 1.0D 2 weeks after cataract surgery were 60.4%,25.9% and 13.7%,respectively.The percentage of absolute refractive errors < 0.5D,0.5D-1.0D and ? 1.0D 1 month after cataract surgery were 62.7%,26.7% and 10.6%,respectively.The percentage of absolute refractive errors < 0.5D,0.5D-1.0D and ? 1.0D 3 months after cataract surgery were 64.1%,26.6% and 9.3%,respectively in Tangdu Hospital.2.Effect of pupil dilation on central anterior chamber depth The preoperative central anterior chamber depth were 2.71 ± 0.56 mm and 2.79 ± 0.53 mm before and after pupil dilation respectively(P< 0.001).The postoperative central anterior chamber depth were 3.60 ± 0.98 mm and 4.45 ± 0.35 mm before and after dilation respectively(P< 0.001).The changes of central anterior chamber depth after cataract surgery were 0.88 ± 0.81 mm and 1.66 ± 0.54 mm before and after dilation respectively(P< 0.001).3.Relationship between the changes of central anterior chamber depth and refractive errors after cataract surgery The absolute refractive errors of the group A(CACD < 1.65mm)and the group B(CACD ? 1.65mm)were 0.60 ± 0.43 mm and 0.44 ± 0.48 mm.The difference between the two groups was not statistically significant(P = 0.05).The refractive errors of group A and group B were + 0.57 ± 0.47 mm and-0.18± 0.62 mm.The difference between the two groups was statistically significant(P<0.001).4.Prediction of the central anterior chamber depth after cataract surgery The postoperative central anterior chamber depth was correlated with the preoperative central anterior chamber depth(P<0.001)and the regression equation is: postoperative central anterior chamber depth = 2.850 + 0.487 × preoperative central anterior chamber depth;The postoperative anterior chamber depth was not correlated with lens thickness(P > 0.05).The postoperative central anterior chamber depth was correlated with the preoperative central anterior chamber depth + 1/2 lens thickness(P<0.001),and the regression equation is: postoperative central anterior chamber depth = 2.358 + 0.422 ×(preoperative central anterior chamber depth + 1/2 lens thickness).5.The correlations between binocular refraction errors after sequential cataract surgery and calculations of the introcular lens in the second eyes cataract surgery The correlation coefficient of binocular refractive errors after sequential cataract surgery was 0.760(P < 0.001).After the intraocular lens diopter of the second eyes were adjusted,the mean absolute refractive error of the second eyes was 0.57 ± 0.41 D while the first eyes was 1.18 ± 0.85 D,and the difference was statistically significant(P <0.001).Conclusions 1.The central anterior chamber depths before and after cataract surgery are increased after pupil dilation.The patients with less change of central anterior chamber depth are more likely to occur hyperopic shift in refractive errors,while the patients with larger change of anterior chamber depth tend to occur myopic shift in refractive errors after cataract surgery.2.The regression formulas of the anterior chamber depth after cataract surgery may be applied to predict the refractive errors clinically.3.Positive correlation in the postoperative refractive errors was significantly shown between two eyes in sequential cataract surgery.The postoperative refractive errors of the second eyes could be reduced by adjusting the intraocular lens diopter based on 50% of postoperative refractive errors of the first eyes.