Analysis On Influencing Factors Of Intraocular Lens Calculation Refractive Errors In Patients With Traumatic Subluxated Lens

Objective:To analyze the accuracy of the prediction of phacoemulsification combined with intraocular lens(IOL)and capsular tension ring(CTR)in treating traumatic subluxated lens,to explore the correlation between refractive errors and anterior chamber depth and axial length,in order to calculate the IOL degree of these patients more accurately in the future.Methods:We retro-spectively reviewed 34 patients with traumatic subluxated lens(34 eyes)who were given phacoemulsification combined with intraocular lens(IOL)and capsular tension ring(CTR)in the First Affiliated Hospital of Guangxi Medical University,from January 2016 to December2018.We measured the preoperative values of eye axis and anterior chamber depth and used the SRK/T formula to calculate intraocular lens power.We collected the data of optometry and anterior chamber depth at 1 month and 3months after surgery.We use SPSS l7.0 to build the database and analyse the statistical relation between postoperative refractive and preoperative andpostoperative ACD and AL.Results:(1)The uncorrected visual acuity and the best corrected visual acuity after surgery were significantly improved in 34 cases(34 eyes)which were in a relatively stable state at 1 month after surgery,with a value of0.49±0.25 D and 0.69±0.24 D,respectively.(2)In 34 cases(34 eyes),the postoperative anterior chamber depth was significantly deeper than the preoperative anterior chamber.And the postoperative anterior chamber depth tend to be stable in 2 weeks after the surgery,with a value of4.24±0.50 mm.(3)The changes of anterior chamber depth in the shallow anterior chamber group,the normal anterior chamber group and the deep anterior chamber group were 2.54±0.61 mm,1.83±0.39 mm and 1.01±0.53 mm,respectively.The refractive errors were 0.43±0.58 D,-0.33±0.54 D and-1.02±0.77 D respectively.The changes of anterior chamber depth and refractive error between the three groups were statistically significant(P<0.05).(4)The postoperative changes in anterior chamber depth group whose fracture range of suspensory ligament of lens >1 quadrant(23 eyes)and the group whose fracture range of suspensory ligament of lens ?1 quadrant(11 eyes)were 2.02±0.86 mm and 2.00±0.70 mm.The refraction errors were-0.18±0.78 D and 0.14±0.95 D,respectively.There were no statistical differences in the anterior chamber depth changes and refraction errors between the two groups(P>0.05).(5)The anterior chamber depth changes of the long eye axis group,the normal eye axis group and the short eye axis group were2.72±0.49 mm,1.87±0.72 mm and 1.25±0.39 mm,respectively.The refractive errors were 0.68±0.46 D,-0.24±0.71 D and-0.96±0.41 D,respectively.The changes of anterior chamber depth and refractive error among the three groups were statistically significant(P<0.05).(6)Postoperative anterior chamber depth,postoperative anterior chamber depth/preoperative anterior chamber depth,axial length,postoperative anterior chamber depth/axial length were positively correlated with postoperative refractive error(P<0.05),and the correlation coefficients were 0.428,0.527,0.552 and 0.389,respectively.Preoperative anterior chamber depth was negatively correlated with postoperative refractive error(P<0.05),and the correlation coefficients were-0.619,respectively.(7)Preoperative anterior chamber depth was negatively correlated with anterior chamber depth(P<0.05),and the correlation coefficient was-0.795.There was a positive correlation between axial length and anterior chamber depth(P<0.05),and the correlation coefficient was 0.771.There was no significant correlation between anterior chamber depth and postoperative anterior chamber depth(P>0.05).(8)There was a linear correlation between postoperative anterior chamber depth and preoperative anterior chamber depth(P=0.028<0.05),and the regression coefficient was 0.195.Linear regression equation: postoperative anterior chamber depth =3.809+0.195×preoperative anterior chamber depth.Conclusion: Patients with traumatic subluxated lens after treating with phacoemulsification combined with intraocular lens(IOL)and capsular tension ring(CTR)get visual acuity improved and anterior chamber deepened.The patients with the shallower anterior chamber and the longer axial length before surgery will get the greater change of anterior chamber depth and are more likely occur hyperopia shift.We should consider the changes of anterior chamber depth after surgery.It is appropriate to increase or decrease the diopter in the calculation of IOL.Postoperative anterior chamber depth was positively correlated with preoperative anterior chamber depth,but the calculation formula still needs to be further verified.