Observation Of Clinical Efficacy Of Posterior Chamber Phakic Refractive Lens Implantation In The Treatment Of Ultra-high Myopia

ObjectivePosterior chamber phakic intraocular lens（PCPIOL）implantation is now becoming more widespread in the field of refractive surgery.The posterior chamber phakic refractive lens（PC-PRL）are kinds of suspended PCPIOL.This study objectively evaluated the clinical efficacy of PC-PRL implantation in the treatment of ultra-high myopia by observing and recording the visual acuity,diopter,intraocular pressure,corneal endothelial cell density,vault,anterior chamber depth and postoperative complications of patients with PC-PRL implantation until 6 months after the operation,and provided more basis for the clinical promotion of PC-PRL implantation.MethodsA retrospective case study approach was used in this study.39 patients（69eyes）with ultra-high myopia who underwent PC-PRL implantation at Lanzhou Huaxia Eye Hospital from January 2021 to January 2022 were selected and divided into two groups,17 patients（31 eyes）in the spherical lens≤-18.00D group and 22 patients（38 eyes）in the spherical lens>-18.00D group,for comparative analysis and clinical efficacy observation.All patients underwent a comprehensive systematic ophthalmic examination to obtain the patients’preoperative and postoperative uncorrected visual acuity（UCVA）,best corrected visual acuity（BCVA）,spherical equivalent（SE）,intraocular pressure（IOP）,corneal endothelial cell density（ECD）,anterior chamber depth（ACD）,and postoperative vault was measured to observe postoperative adverse conditions or complications.The effective index（postoperative BCVA/preoperative BCVA）and the safety index（postoperative BCVA/preoperative BCVA）were calculated,and the ECD loss rate（（4））was calculated:（preoperative ECD-postoperative ECD）/preoperative ECD×100（4）).Paired t-test was used for comparison before and after surgery,independent sample t-test was used for comparison between two groups,x²test and Bonferroni method was used for comparison of rates between two groups,repeated-measures ANOVA was used for comparison at different time points before and after surgery,and LSD t-test was used for two-by-two comparison at different time points.A difference was considered statistically significant at P<0.05.ResultsA total of 39 patients（69 eyes）with ultra-high myopia were included in this study.The patients were divided into 17 cases with 31 eyes in the spherical lens≤-18.00D group and 22 cases with 38 eyes in the spherical lens>-18.00D group according to the preoperative spherical lens prescription.The mean effective index at 6 months postoperatively was 1.30±0.28 and the mean safety index was1.38±0.58 in the spherical lens≤-18.00D group,and the mean effective index was 1.80±0.25 and the mean safety index was 1.47±0.18 in the spherical lens>-18.00D group.The UCVA of all patients reached or exceeded the preoperative BCVA at 6 months postoperatively,and the difference between the two groups was statistically significant（x²=27.960,P（27）0.01）.The differences in postoperative visual acuity between the two groups were statistically significant for both group and time comparisons(F _intergroup=77.971,P _intergroup<0.01;F _time=11.780,P _time<0.01),while the differences in interaction comparisons were not statistically significant(F _interaction=0.561,P _interaction=0.729).The mean preoperative SE in the spherical lens≤-18.00D group was（-13.41±2.17）D,and the mean 1 day postoperative SE and 6months postoperative SE were（0.04±1.55）D and（-0.13±0.75）D;the mean preoperative SE in the spherical lens>-18.00D group was（-24.06±3.20）D,and the mean SE at 1 day postoperatively and 6months postoperatively were（-0.26±1.43）D,（-0.44±1.10）D,respectively.The difference in SE at 1 day postoperatively compared to preoperatively was statistically significant between the two groups（t=26.310,49.928,both P<0.01）.There was no statistically significant difference in SE between groups and time during the postoperative follow-up period between the two groups(F _group=0.832,P _group=0.365;F _time=0.930,P _time=0.468),and there was a statistically significant difference in the interaction comparison(F _interaction=2.538,P _interaction（27）0.05).The IOP was within the normal range before and after surgery in both groups,and the difference between IOP groups and interactions during the follow-up period before and after surgery in both groups was not statistically significant(F _time=0.152,P _time=0.698;F _interaction=0.399,P _interaction=0.877);the difference in time comparison was statistically significant(F _time=8.172,P _time（27）0.01).In both groups,the ECD decreased significantly at 1 day and 6 months postoperatively compared with the preoperative period,and the differences were statistically significant（all P<0.01）,and the mean ECD loss rates at 1 day postoperatively were（14.63±0.25）cells/mm²,（19.78±0.23）cells/mm²,and the mean postoperative 6 months ECD loss rate was（13.86±0.22）（4）,（18.39±0.18）（4）,and the differences between the two groups in the postoperative 1 day and postoperative 6 months ECD loss rates were not statistically significant（all P>0.05）.There was no statistically significant difference at each time point in the1 day postoperative 6 months follow-up period（P>0.05）.The 1 day postoperative vaults were（370.23±170.92）μm and（339.37±254.74）μm in the two groups,respectively;the 6 months postoperative vaults were（329.00±131.77）μm,（288.42±156.26）μm;6months postoperative versus 1 day postoperative vault decreased by 35.00（-14.00,69.00）μm,31.50（-31.50,110.75）μm,with no statistically significant differences（all P>0.05）.There was a statistically significant difference in the time of vault comparison between the two groups of patients at different time points after surgery(F _time=12.247,P _time<0.01),and there was no statistically significant difference between groups or interactions(F _intergroup=1.079,P _intergroup=0.303;F _interaction=2.231,P _interaction=0.062).The difference between the preoperative ACD of the two groups was statistically significant（t=3.223,P<0.01）;the difference between the postoperative 6 months ACD of the two groups was statistically significant（t=3.508,P<0.01）;the postoperative 6 months ACD of the two groups was lower than that before surgery,and the difference was statistically significant（t=10.243,13.272,both P<0.01）.No serious intraoperative or postoperative complications occurred in both groups,and only a small number of patients experienced early acute IOP elevation after surgery,which were all manageable.ConclusionsPC-PRL implantation is safe and effective for correction of ultra-high myopia.Patients with ultra-high myopia had good improvement of visual acuity,stable refractive status,safety and reliability,and no serious complications in the early postoperative period.