Accuracy of optimized Sirius ray-tracing method in intraocular lens power calculation

AIM:To evaluate the accuracy and predictability of ray tracing-assisted intraocular lens(IOL) calculation function in Sirius internal software and further improve the accuracy by optimizing the calculation of predicted lens position(PLP).METHODS:This retrospective study recruited 52 eyes of 49 patients.All of the cases with cataract had undergone phacoemulsification combined with IOL implantation.SRK-T,Haigis formula,and Sirius ray-tracing method were all used for each eye’s IOL calculation.The mean absolute value of prediction error(prediction error=predicted refraction-postoperative refraction) was defined as mean absolute prediction error(MAPE) and was determined for each method.Calculation of PLP was optimized by effective lens position(ELP).Optimized PLP was entered to Sirius internal software again to verify whether the method was improved.RESULTS:Compared with SRK-T and Haigis formulas,less accuracy was shown in Sirius ray-tracing method(P=0.001).The ELP of the IOL moved forward compared to PLP(P<0.001).The MAPE of the ELP-inputted Sirius ray-tracing method was reduced.ELP and PLP were well correlated.Taking ELP as y and PLP given by Sirius soft as x,a linear regression formula y=0.1637 x+3.1741 was concluded(R^(2)=0.1066,P=0.018).It was shown that the optimized Sirius ray-tracing method(optimized PLP entered),compared with SRK-T and Haigis formulas,worked with the same accuracy(P=0.038).CONCLUSION:The original Sirius ray tracing method is not satisfactory enough.However,in normal eyes,the optimized Sirius ray-tracing method in IOL calculation was as accurate as SRK-T and Haigis formulas.

Changes in Schlemm’s canal,trabecular meshwork,and relevant parameters in the early stage after SMILE of myopia patients

AIM:To observe the changes in Schlemm’s canal(SC),trabecular meshwork(TM),and anterior chamber relevant parameters after small incision lenticule extraction(SMILE) of myopia patients.METHODS:A total of 58 eyes from 30 patients who underwent SMILE were divided into a low and moderate myopia group(group A,32 eyes) and a high myopia group(group B,26 eyes).The diameter and area of the SC,the width and thickness of TM obtained by CIRRUS HD-OCT5000,and the related anterior chamber parameters obtained by Pentacam anterior segment analysis system,accommodation amplitude(AMP) were observed pre-and postoperatively.The preoperative intraocular pressure(IOP) and postoperative correction of intraocular pressure(IOPcc) were measured.RESULTS:The diameter and area of the SC in the two groups were significantly increased postoperatively(all P<0.01).The TM width of the patients in the two groups were increased at 1mo after surgery(both P<0.01),but the TM thickness did not change(P>0.05).The corneal curvature,central anterior chamber depth,and anterior chamber volume decreased after SMILE surgery(all P<0.01).There was a weak negative correlation between the SC area change and AMP change in group A(r=-0.362,P<0.01).The postoperative IOP decreased after correction by Shah formula(P<0.05).CONCLUSION:SC and TM in myopia patients change in the early postoperative stage of SMILE and the IOP is decline.

Corneal histomorphology and electron microscopic observation of R124L mutated corneal dystrophy in a relapsed pedigree

·AIM:To investigate the histological characteristics and ultrastructure of recurrent Chinese R124 L mutated corneal dystrophy after keratoplasty.·METHODS:The subjects were enrolled from a Chinese family of corneal dystrophy with R124 L heterozygous gene mutation and with a history of consanguineous marriage.Normal corneal samples were used as controls.·RESULTS:In this family,2 patients(3 eyes)underwent penetrating keratoplasty(PKP)and 2 patients(4 eyes)underwent lamellar keratoplasty(LKP).They had recurrence at 33.5±3.0(range 30-36)mo after keratoplasty.Among them,1 patient(1 eye)underwent PKP again and 1 patient(2 eyes)underwent LKP again.In the R124 L mutated recurrent corneal dystrophy,the corneal turbidity was mainly distributed from the upper corneal cortex to the anterior stroma;the corneal epithelium surface was rougher and more uneven;and,the corneal erosions were larger.Hematoxylin-eosin staining showed that the thickness of the corneal epithelium was uneven;the arrangement of the epithelial cells was disordered;and,some corneal epithelial cells were swollen.The results of Congo red staining,Masson’s trichrome staining and Periodic acid-Schiff staining were positive,while that of Alcian blue staining was negative.Under a transmission electron microscope,deposition of high electron density substances between epithelial and basal cells,and,apoptosis of basal cells were observed.Many high electron density depositions were observed in the sub-epithelial and anterior corneal matrix.·CONCLUSION:In the Chinese family of recurrent corneal dystrophy with R124 L gene mutation,the corneal epithelia of the recurrent cases are rougher,and the corneal depositions are extra cellular amyloid fibrin.

Dynamic assessment of variations in pupil diameter using swept‑source anterior segment optical coherence tomography after phakic collamer lens implantation

Purpose:To dynamically assess variations in pupil diameter induced by changes in brightness in myopic eyes implanted with an implantable collamer lens(ICL,STAAR Surgical)with a central port.Methods:This prospective,observational single-center case series study comprised 65 eyes from 65 consecutive patients undergoing ICL implant.A modified commercially available swept-source Fourier-domain anterior segment optical coherence tomography(AS-OCT)device was used for imaging and performing dynamic pupillometry under changing light conditions before and after a mean follow-up interval of four months after surgery.Results:Preoperative mean pupil size under photopic conditions was 3.38±0.64 mm;after surgery,this increased to 3.48±0.61 mm.Mean pupil size under scotopic light conditions was 5.72±0.79 mm before surgery and 5.84±0.77 mm postoperatively.The differences between preoperative and postoperative pupil diameter in miosis and mydriasis were 0.10±0.44 mm(P=0.078)and 0.12±0.58 mm(P=0.098),respectively.The scotopic pupil exceeded the optic zone of the implanted lens in 39 eyes(60%).The mean central vault value was 412±177μm under maximum miosis and 506±190μm under maximum mydriasis.We found a positive correlation between vault and differences in pupil diameter under all light conditions(P<0.05).Conclusion:Dynamic AS-OCT enables a very precise determination of the pupillary diameter in the iris plane.The changes in the pupil diameter under different light conditions after the implantation of an ICL are related to the postoperative vault.

Dynamic assessment of variations in pupil diameter using swept-source anterior segment optical coherence tomography after phakic collamer lens implantation

Purpose To dynamically assess variations in pupil diameter induced by changes in brightness in myopic eyes implanted with an implantable collamer lens(ICL,STAAR Surgical)with a central port.Methods This prospective,observational single-center case series study comprised 65 eyes from 65 consecutive patients undergoing ICL implant.A modified commercially available swept-source Fourier-domain anterior segment optical coherence tomography(AS-OCT)device was used for imaging and performing dynamic pupillometry under changing light conditions before and after a mean follow-up interval of four months after surgery.Results Preoperative mean pupil size under photopic conditions was 3.38±0.64 mm;after surgery,this increased to 3.48±0.61 mm.Mean pupil size under scotopic light conditions was 5.72±0.79 mm before surgery and 5.84±0.77 mm postoperatively.The differences between preoperative and postoperative pupil diameter in miosis and mydriasis were 0.10±0.44 mm(P=0.078)and 0.12±0.58 mm(P=0.098),respectively.The scotopic pupil exceeded the optic zone of the implanted lens in 39 eyes(60%).The mean central vault value was 412±177μm under maximum miosis and 506±190μm under maximum mydriasis.We found a positive correlation between vault and differences in pupil diameter under all light conditions(P<0.05).Conclusion Dynamic AS-OCT enables a very precise determination of the pupillary diameter in the iris plane.The changes in the pupil diameter under different light conditions after the implantation of an ICL are related to the postoperative vault.