Comparison of surgically induced astigmatism in various incisions in manual small incision cataract surgery

AIMTo determine the surgically induced astigmatism (SIA) in Straight, Frown and Inverted V shape (Chevron) incisions in manual small incision cataract surgery (SICS).

Comparison of surgically induced astigmatism among different surgeons performing the same incision

To compare surgically induced astigmatism （SIA） of different surgeons, who perform the same main incision. Two hundred and seventy eyes underwent cataract surgery with phacoemulsification by four different surgeons （A, B, C, and D）. A 3-step, 3.0 mm, superotemporal for the right eye and superonasa! for the left eye clear corneal incision was performed. A comparison in SlA among A, B, C and D surgeon was made. No significant difference was found in SlA at both first and sixth postoperative month between different surgeons （P〉0.05）. SIA is more dependent on incisional characteristics and preoperative astigmatism and less on the surgeon.

Comparison of surgically induced astigmatism in patients with horizontal rectus muscle recession

·AIM: To compare surgically induced astigmatism(SIA)following horizontal rectus muscle recession surgery between suspension recession with both the 'hang-back' technique and conventional recession technique.·METHODS: Totally, 48 eyes of 24 patients who had undergone horizontal rectus muscle recession surgery were reviewed retrospectively. The patients were divided into two groups. Twelve patients were operated on by the hang-back technique(Group 1), and 12 by the conventional recession technique(Group 2). SIA was calculated on the 1stwk, 1stand in the 3rdmo after surgery using the SIA calculator.·RESULTS: SIA was statistically higher in the Group 1all postoperative follow-up. SIA was the highest in the 1st wk, and decreased gradually in both groups.·CONCLUSION: The suspension recession technique induced much more SIA than the conventional recession technique. This difference also continued in the following visits. Therefore, the refractive power should be checked postoperatively in order to avoid refractive amblyopia.Conventional recession surgery should be the preferred method so as to minimize the postoperative refractive changes in patients with amblyopia.

Surgically Induced Corneal Astigmatism Following Cataract Surgery

Aim: To study the surgically induced astigmatism (SIA) caused by two different type main incisions in phacoemulsification. Methods: Sixty-eight eyes of 65 patients who underwent phacoemul-sification were randomly divided into two groups according to main incision type: 2.8 mm superior limbal incision (in Group 1) and 2.8 mm upper clear corneal incision (in Group 2). Surgical techniques did not differ between the groups except for the main incisions. All patients received detailed ophthalmological examination in addition to keratometry at the pre- and post-operatively. The preoperative and postoperative astigmatisms were calculated by the vector analysis method and the SIA was compared between the groups. Results: The mean SIA values were 1.3 ± 0.67 D, 0.89 ± 0.47 D, 0.77 ± 37 D in Group 1 and 1.42 ± 0.62 D, 1.15 ± 0.54 D, 0.94 ± 0.47 D in Group 2 on the first day, first week and first month postoperatively, respectively. According to the vector analysis, SIA was less in Group 1 than Group 2;although the difference was not statistically significant (p > 0.05). Conclusion: Although less astigmatism was detected in the superior limbal incision group, this difference was not statistically significant.

Refractive outcomes after V4c Toric collamer lens implantation over 1y of follow-up

AIM:To evaluate refractive outcomes and corneal astigmatism changes after Toric implantable collamer lens with a central port(V4c T-ICL)implantation over 1y of follow-up.METHODS:A retrospective study was performed including 50 eyes of 50 patients that underwent V4c T-ICL implantation.Uncorrected(UDVA)and corrected(CDVA)distance visual acuities,refraction,refractive and corneal astigmatism changes and corneal coupling correction were evaluated preoperatively,1 and 12mo postoperatively.Vector analysis was used for astigmatism changes.Coefficient of adjustment(CAdj)was calculated for corneal coupling analysis.RESULTS:The mean UDVA achieved was 0.03 logMAR at 1mo and remained unchanged throughout the whole follow-up(P=0.193).At the last visit,84%of the eyes achieved a CDVA of 0.00 logMAR or better.Regarding spherical equivalent refraction(SEQ),96%of eyes were ranges of±1.00 D and 84%of them within±0.50 D.Also,94%of eyes had a remaining refractive cylinder within±1.00 D and 78%of them within±0.50 D.Both,SEQ and refractive cylinder,remain stable over the postoperative follow-up(P=1.000 and P=0.660,respectively).In terms of surgically induced astigmatism(SIA),no statistically significant differences were found over the follow-up(P=0.102)and under correction was found with a correction index lower than the unit at each visit.A keratometric astigmatism induced of 0.59±0.53(vector mean:0.26×73º)D was reached at the last visit.No significant changes in terms of corneal astigmatism orientation were reported over post-surgery visits(P=0.129 and P=0.097 at 1 and 12mo respectively).No clinical significance was found for CAdj on with-the-rule astigmatism.No postoperative complications resulting from the surgery were found.CONCLUSION:Refractive outcomes suggest that the V4c T-ICL implantation for correction of myopic astigmatism was satisfactory in terms of effectiveness,safety,and stability during 1y of follow-up.Corneal astigmatism induced by the incision around 0.5 D is achieved according to the remaining refractive cylinder found at one-year post-surgery.Corneal coupling analysis results in no unexpected spherical change.

The Comprehensive Control of Astigmatism during and Following Intraocular Lens Implantation.

The operating corneoloscope and Terry operative keratometer were used respectively in 29 and 34 eyes during the intraocular lens implantation to measure the corneal astigmatism qualitatively or quantitatively,so that the tension of incision closure could be adjusted. The surgically induced astigmatism in qualitative group two weeks after the operation was 3. 5 ± 1. 70 D and that in quantitative group was 2. 56±1. 60 D. There were 55.17% and 38. 24% of the eyes with over 2. 00 D corneal astigmatism in qu...

The impact of posterior corneal astigmatism on the surgical planning of toric multifocal intraocular lens implantation

Purpose:To investigate the influence of posterior corneal astigmatism on the prediction accuracy of toric multi­focal intraocular lens(IOL)calculation.Methods:The keratometric astigmatism measured by Lenstar LS 900(KCA_(L)),keratometric astigmatism(KCAp)and total corneal astigmatism(TCA)measured by Scheimpflug camera(Pentacam HR)were documented and analyzed accordingly.Three deduction models using different parameters were compared.Model 1:KCA_(L)+keratometric comeal surgically induced astigmatism(KCSIA,0.30 D@50°);Model 2:KCA_(P)+KCSIA);Model 3:TCA 4-total CSIA(TCSIA,0.23 D@50°).The prediction errors of each model as the difference vector between the actual and the intended residual astigmatism were compared.Results:Seventy-six eyes implanted with toric multifocal IOLs were included in this study.The vector differences of the actual KCSIA and TCSIA were statistically significant in the total sample and against-the-rule(ATR)sub­group(both P<0.05).Model 1 deduced the smallest mean values of prediction error,while that of Model 3 were smaller than that of Model 2,both in the total sample and the ATR subgroups(all P<0.05).Meanwhile,in the total sample and ATR subgroups,the centroid vector magnitudes of Model 3 were smaller than that of Model 1(0.31±0.76 D and 0.39±0.76 D).Conclusions:The calculation of toric multifocal IOL should be individualized especially in the ATR eyes for the impact of PCA on the estimation of the preoperative comeal astigmatism and the CSIA.

Surgically induced astigmatismCorneal astigmatismMeanSummated vector meanCentroidVector analysisTemporal incisionSuperior incisionICL implantation

BackgroundTo compare the arithmetic mean (M-SIA) and the summated vector mean of surgically induced astigmatism (SVM-SIA) according to the incision site after phakic intraocular lens (Visian implantable collamer lens (ICL), STAAR Surgical) implantation.MethodsThis study comprised 121 eyes of 121 consecutive patients undergoing ICL surgery through a 3.0-mm temporal or superior clear corneal incision. The magnitude and the axis of corneal astigmatism preoperatively and 3 months postoperatively were measured using an automated keratometer. The M-SIA and the SVM-SIA were determined according to the incision site.ResultsThe magnitude of corneal astigmatism significantly increased from 1.23 ± 0.59 D preoperatively to 1.46 ± 0.72 D postoperatively in the temporal incision group (Wilcoxon signed-rank test, P < 0.001), but it significantly decreased from 1.09 ± 0.36 D preoperatively to 0.86 ± 0.41 D postoperatively in the superior incision group (P < 0.001). The M-SIA was 0.48 ± 0.30 D, and the SVM-SIA was 0.23 ± 0.52 D at a meridian of 82° in the temporal incision group. The M-SIA was 0.57 ± 0.30 D, and the SVM-SIA was 0.47 ± 0.45 D at a meridian of 1° in the superior incision group.ConclusionsICL implantation induces the M-SIA by approximately 0.5 D, but the SVM-SIA decreased to 50% and 80% of the M-SIA in magnitude through temporal and superior incisions, respectively. The direction of the SVM-SIA showed a tendency toward corneal flattening to the incisional site. It should be noted that the M-SIA is somewhat different from the SVM-SIA according to the incision site.

Comparison of magnitude and summated vector mean of surgically induced astigmatism vector according to incision site after phakic intraocular lens implantation

Background:To compare the arithmetic mean(M-SIA)and the summated vector mean of surgically induced astigmatism(SVM-SIA)according to the incision site after phakic intraocular lens(Visian implantable collamer lens(ICL),STAAR Surgical)implantation.Methods:This study comprised 121 eyes of 121 consecutive patients undergoing ICL surgery through a 3.0-mm temporal or superior clear corneal incision.The magnitude and the axis of corneal astigmatism preoperatively and 3 months postoperatively were measured using an automated keratometer.The M-SIA and the SVM-SIA were determined according to the incision site.Results:The magnitude of corneal astigmatism significantly increased from 1.23±0.59 D preoperatively to 1.46±0.72 D postoperatively in the temporal incision group(Wilcoxon signed-rank test,P<0.001),but it significantly decreased from 1.09±0.36 D preoperatively to 0.86±0.41 D postoperatively in the superior incision group(P<0.001).The M-SIA was 0.48±0.30 D,and the SVM-SIA was 0.23±0.52 D at a meridian of 82°in the temporal incision group.The M-SIA was 0.57±0.30 D,and the SVM-SIA was 0.47±0.45 D at a meridian of 1°in the superior incision group.Conclusions:ICL implantation induces the M-SIA by approximately 0.5 D,but the SVM-SIA decreased to 50%and 80%of the M-SIA in magnitude through temporal and superior incisions,respectively.The direction of the SVM-SIA showed a tendency toward corneal flattening to the incisional site.It should be noted that the M-SIA is somewhat different from the SVM-SIA according to the incision site.