| Background:Cataract surgery by phacoemulsification is a widely performed procedure worldwide.However following cataract extraction many people appreciate the benefits but also some report their misfortune due to complications.In this study we observed the biometric changes that occur in the eye following the surgical procedure.The applied benefits of this research in clinical practice is the information can be used in designing an intraocular lens(IOL)that will closely preserve the previous anatomical state of the human eye following cataract surgery.Replacing the human crystalline lens by a thinner intraocular lens leaves room for forward vitreous movement leading to severe complications,hence if IOLs are designed in such a way that the changes following surgery are minimal,they can be more ideal in preserving the anatomy and also of greater comfort to the patients with minimal postoperative complications.Purpose: The aim of this study is to investigate the early biometric changes that occur in the human eye following uneventful conventional phacoemulsification and implantation of intraocular lens of different designs into the capsular bag.This research along with intraocular pressure and biometric changes shall also provide more insight about which design of intraocular lens favours the previous anatomical state of the vitreo-lenticular interface,cause less forward movement of the vitreous and also which type of intraocular lens design will be more comfortable for the patients and cause less complications post-operatively.Materials and methods: This is a retrospective comparative study consisting of 100 eyes from 100 patients who underwent cataract surgery by conventional phacoemulsification and implantation of intraocular lens into the capsular bag at the Second Affiliated Hospital of Dalian Medical University from March 2016 to January 2017.The patients were labelled into four groups each consisting of 25 eyesdepending on the type of IOL implanted.Group 1 was those implanted with Rayner IOL(n=25),group 2 with Hoya IOL(n=25),group 3 with Bigbag IOL(n=25)and group 4 with Re STOR IOL(n=25).Patients taken in our study in all four groups had a cataract lens thickness(LT)in the range of 4.00 to 5.00 mm,so that there is no significant difference between the LT of the groups and nearly same size of cataract will be emulsified.Data such as the depth of anterior chamber(ACD),axial length of the eyeball(AL),the distance from the posterior lens capsule to the internal limiting membrane of the retina,visual acuity both uncorrected(UCDVA)and best corrected for distance(BCDVA)and intraocular pressure(IOP)were measured before and after one month following the cataract surgery.Statistical analysis of the data was performed using IBM SPSS for windows version 20.0.As the data was normally distributed,One-Way ANOVA was used to compare the change in ACD,BCDVA,UCDVA,AL,IOP,and the mean change in distance from the posterior lens capsule to the internal limiting membrane of retina to find out if there was any significant difference among the four different groups.A value of p<0.05 was considered as statistically significant.Results:The study consisted of 100 eyes from 44 male(44%)and 56 female(56%)patients in the age range of 53 to 86 years old,with a mean age of 72.28±7.10 yearswho were diagnosed with cataract and had undergone cataract surgery by conventional phacoemulsification technique.There was no significant difference in the mean score of LT between the four groups chosen before operation(F=2.564,p=0.059).There was no statistical significant difference in age in between the four groups(F=0.709,p=0.549).The χ2 univariate test showed that p>α,(χ2=0.974,p=0.808),implying that there was no statistical significance between gender and the four groups.The preoperative UCDVA was 0.21±0.06 for group 1,0.17±0.07 for group 2,0.06±0.02 for group 3 and 0.20±0.08 for group 4(F=30.569,p=0.000).Postoperatively after 1 month it was 0.54±0.10,0.58±0.10,0.08±0.03 and 0.56±0.08 for each groups respectively with statistical significant difference in UCDVA between the groups following the operation(F=216.383,p=0.000).Preoperatively the BCDVA for group 1 was 0.25±0.09,group 2 was 0.19±0.09,group 3 was 0.08±0.48 and was 0.23±0.10 for the fourth group(F=18.129,p=0.000).There is a better BCDVA postoperatively at one month with a value of 0.77±0.14 for the group 1 implanted with Rayner IOL,0.85±0.14 for group 2 implanted with Hoya IOL,0.22±0.10 for group 3 implanted with Bigbag IOL and 0.86±0.12 for group 4 implanted with Re STOR IOL(F=140.419,p=0.000).The distance from the posterior lens capsule to the internal limiting membrane of the retina was 15.77±1.17 mm for group 1,15.94±0.72 mm for group 2,21.03±1.95 mm for group 3 and 16.40±0.87 mm for group 4.The value changed postoperatively and increased to 17.70±1.22 mm for the first group implanted with Rayner IOL,17.89±0.64 mm for second group implanted with Hoya IOL,22.50±1.94 mm for the third group implanted with Bigbag IOL,and 18.32±0.67 mm for group four implanted with Re STOR IOL.On multiple comparison,the change in distance from posterior lens capsule to the internal limiting membrane of retina following cataract surgery in Bigbag IOL implanted group was(1.47±0.18)mm and was significantly different from the other three groups(p<0.05).The preoperative axial length decreased from a value of 23.38±1.10 mm for group 1 to 23.15±1.02 mm,for group 2 from 23.26±0.68 mm to 23.18±0.67 mm,for group 3 from 28.62±1.85 mm to 28.55±1.84 mm and for group 4 from 23.73±0.61 mm to 23.60±0.61 mm.There was a significant difference in axial length after performing the cataract operation(F=131.593,p=0.000).The anterior chamber depth(ACD)was 2.75±0.48 mm for group 1,2.51±0.39 mm for group 2,2.78±0.35 mm for group 3 and 2.50±0.46 mm for the fourth group before cataract operation.Postoperatively at one month the anterior chamber depth deepened to 3.93±0.54 mm,3.69±0.39 mm,5.07±0.36 mm and 3.72±0.46 mm respectively for the above groups.There was a significant difference in ACD after the cataract operation(F=54.274,p=0.000).On multiple comparison mean score of ACD for the group implanted with Bigbag IOL was significantly different from the other three groups(p=0.000).The intraocular pressure(IOP)preoperatively was 16.80±1.44 mmHg for group 1,16.92±1.66 mm Hg for group 2,16.96±1.46 mm Hg for group 3 and 16.68±1.35 mm Hg for group 4.Postoperatively it was decreased to 14.84±1.52 mm Hg for group 1,14.80±1.66 mm Hg,14.92±1.63 mm Hg and 15.08±1.61 mm Hg for the above groups respectively.All the four groups indicate a change in IOP following cataract surgery.However no statistically significant difference in change in IOP was found postoperatively between the four groups(F=1.695,p=0.173).Conclusion:Following cataract surgery there occur biometric changes in the eye,this can be attributed to the breaking down of the human lens and removing it into pieces by phacoemulsification and replacing the human crystalline lens by a thinner IOL.Our study proved the following important things:1.Cataract surgery changes the ocular biometric parameters involving the anterior and posterior segment of the eye,leading to deepening of the anterior chamber,an increase in the distance from posterior lens capsule to the internal limiting membrane of the retina and also a decrease in the axial length.This is irrespective of the type or design of the intraocular lens implanted following phacoemulsification as evidenced by the biometric changes in all the four different groups implanted with different types of IOL in our study.2.The design of the Bigbag IOL gives it a greater advantage over preserving or causing minimal change in the distance from posterior lens capsule to internal limiting membrane of retina,hence allowing less forward vitreous shift following cataract extraction.This lens with its optical shape design gives a greater stability and support to the vitreous and is safer for the high myopia patients.Hence better IOL designs which can mimic the shape and size of the human crystalline lens along with good support to the vitreous,will give a better post-operative stability of the vitreous,less forward displacement,better patient comfort,and less complications like retinal detachment following cataract extraction.3.There is a reduction in intra-ocular pressure following cataract surgery irrespective of the design of IOL implanted in the eye.This is evidenced by our results showing a decrease in IOP in all four groups following cataract extraction. |
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