Effectiveness of toric soft contact lenses for vision correction in patients with different degrees of astigmatism: a real-world study

AIM:To assess the visual correction of patients with different degrees of astigmatism with toric soft contact lenses(TSC).METHODS:It was a real-world study with prospective and single-arm design.A total of 384 patients with astigmatism who came for TSC fitting and alignment from November 2022 to January 2023 were included.According to the difference in astigmatism,patients were divided into groups A(cylinder degree:-0.75 to-0.50 D),B(cylinder degree:-1.75 to-1.00 D)and C(cylinder degree≤-2.00 D),and followed up on the day of wear,1wk,1 and 3mo,mainly to observe visual acuity,refraction,lens fit,visual quality and comfort at 1wk after wear.The visual acuity success rate and the overall success rate of the fitting were evaluation indicators(taking into account the four dimensions of visual acuity,fitting,quality of vision and comfort).The visual acuity success rate was calculated by taking“corrected visual acuity with contact lenses is no less than 1 line or better than best spectacle-corrected visual acuity”(i.e.corrected visual acuity with contact lenses is 1 line below,equal to,one line above or more than best spectaclecorrected visual acuity)as the criterion for visual success,and the the overall success rate of the fitting was calculated by using the comprehensive indicators(visual acuity,fit,visual quality,comfort)to meet certain conditions as the judgment criteria for successful fitting.RESULTS:After 1wk of wearing TSC,the visual acuity success rates of patients were 100%(207/207),98.58%(139/141)and 97.22%(35/36)in the three groups,respectively,with residual cylinder closed to 0.The acceptability of the lens fitting was over 95%;the incidence of adverse visual symptoms was within 10%and the comfort acceptability was over 97%.The overall success rate of fitting for patients with high,medium and low astigmatism was 93.72%(194/207),90.78%(128/141)and 88.89%(32/36),respectively.CONCLUSION:TSC(model:G&G POP·CT)are effective in correcting astigmatism in patients with different degrees of astigmatism.

Oxygen permeability of soft contact lenses in different pH, osmolality and buffering solution

AIMTo determine the effect of pH, osmolality, and buffering system on the oxygen permeability (Dk) of soft contact lenses.METHODSTwo hydrogel lenses (nelfilcon A and etafilcon A) and 2 silicone hydrogel lenses (lotrafilcon A and balafilcon A) were used in the study. These lenses were incubated in phosphate-buffered saline (PBS) and borate-buffered saline (BBS) solutions adjusted by 0.8 pH increments to a pH in the range of 5.8-9.0 or in hypotonic (280 mOsmol/kg), isotonic (310 mOsmol/kg) and hypertonic (380 mOsmol/kg) PBS solutions. Polarographic method was used for measuring the Dk and lenses were stacked as 4 layers to correct the boundary effect.RESULTSDk values of all contact lenses measured in BBS solutions were more stable than those in PBS solutions. Especially the etafilcon A lens showed a relative big change compared with other types of contact lenses at the same conditions. When the osmolality of PBS solution increased from hypotonic to hypertonic, Dk of all contact lenses decreased. Variations in Dk existed depending on lens materials, etafilcon A lens was the most affected and nelfilcon A was the least affected by osmolality.CONCLUSIONFrom the result obtained, it is revealed that Dk of contact lenses is changed by the pH, osmolality, and buffering condition of tear. Thus, Dk of contact lens can be varied by the lens wearers' physiological and/or pathological conditions.

Visual quality of juvenile myopes wearing multifocal soft contact lenses

Background:It is unclear whether multifocal soft contact lenses(MFSCLs)affect visual quality when they are used for myopia control in juvenile myopes.The aim of this study was,therefore,to investigate the effect of MFSCLs on visual quality among juvenile myopia subjects.Methods:In a prospective,intervention study,thirty-three juvenile myopes were enrolled.Visual perception was assessed by a quality of vision(QoV)questionnaire with spectacles at baseline and after 1 month of MFSCL wear.At the one-month visit,the high(96%)contrast distance visual acuity(distance HCVA)and low(10%)contrast distance visual acuity(distance LCVA)were measured with single vision spectacle lenses,single vision soft contact lenses(SVSCLs)and MFSCLs in a random order.Wavefront aberrations were measured with SVSCLs,with MFSCLs,and without any correction.Results:Neither distance HCVA(p>0.05)nor distance LCVA(p>0.05)revealed any significant difference between MFSCLs,SVSCLs and single vision spectacle lenses.The overall score(the sum of ten symptoms)of the QoV questionnaire did not show a statistically significant difference between spectacles at baseline and after 1 month of MFSCL wear(p=0.357).The results showed that the frequency(p<0.001),severity(p=0.001)and bothersome degree(p=0.016)of halos were significantly worse when wearing MFSCLs than when wearing single vision spectacle lenses.In contrast,the bothersome degree caused by focusing difficulty(p=0.046)and the frequency of difficulty in judging distance or depth perception(p=0.046)were better when wearing MFSCLs than when wearing single vision spectacle lenses.Compared with the naked eye,MFSCLs increased the total aberrations(p<0.001),higher-order aberrations(p<0.001),trefoil(p=0.023),coma aberrations(p<0.001)and spherical aberrations(SA)(p<0.001).Compared with the SVSCLs,MFSCLs increased the total aberrations(p<0.001),higher-order aberrations(p<0.001),coma aberrations(p<0.001)and SA(p<0.001).The direction of SA was more positive(p<0.001)with the MFSCLs and more negative(p=0.001)with the SVSCLs compared with the naked eye.Conclusions:Wearing MFSCLs can provide satisfactory corrected visual acuity(both distance HCVA and distance LCVA).Although the lenses increased the aberrations,such as total aberrations and higher-order aberrations,there were few adverse effects on the distance HCVA,distance LCVA and visual perception after 1 month of MFSCL use.

Visual quality of juvenile myopes wearing multifocal soft contact lenses

Background:It is unclear whether multifocal soft contact lenses(MFSCLs)affect visual quality when they are used for myopia control in juvenile myopes.The aim of this study was,therefore,to investigate the effect of MFSCLs on visual quality among juvenile myopia subjects.Methods:In a prospective,intervention study,33 juvenile myopes were enrolled.Visual perception was assessed by a quality of vision(QoV)questionnaire with spectacles at baseline and after one month of MFSCL wear.At the one month visit,the high(96%)contrast distance visual acuity(distance HCVA)and low(10%)contrast distance visual acuity(distance LCVA)were measured with single-vision spectacle lenses,single-vision soft contact lenses(SVSCLs)and MFSCLs in a random order.Wavefront aberrations Were measured with SVSCLs,MFSCLs and,without anycorrection.Results:Neither distance HCVA(P>0.05)nor distance LCVA(P>0.05)revealed any significant difference between MFSCLs,SVSCLs and single-vision spectacle lenses.The overall score(the sum of ten symptoms)of the QoV questionnaire did not show a statistically significant difference between spectacles at baseline and after one month of MFSCL wear(P=0.357).The results showed that the frequency(P<0.001),severity(P=0.001)and bothersome degree(P=0.016)of halos were significantly worse when wearing MFSCLs than when wearing single-vision spectacle lenses.In contrast,the bothersome degree caused by focusing difficulty(P=0.046)and the frequency of difficulty in judging distance or depth perception(P=0.046)were better when wearing MFSCLs than when wearing single-vision spectacle lenses.Compared with the naked eye,MFSCLs increased the total aberrations(P<0.001),higher-order aberrations(P<0.001),trefoil(P=0.023),coma aberrations(P<0.001)and spherical aberrations(SA)(P<0.001).Compared with the SVSCLs,MFSCLs increased the total aberrations(P<0.001),higher-order aberrations(P<0.001),coma aberrations(P<0.001)and SA(P<0.001).The direction of SA was more positive(P<0.001)with the MFSCLs and more negative(P=0.001)with the SVSCLs compared with the naked eye.Conclusions:Wearing MFSCLs can provide satisfactory corrected visual acuity(both distance HCVA and distance LCVA).Although the lenses increased the aberrations,such as total aberrations and higher-order aberrations,there were few adverse effects on the distance HCVA,distance LCVA and visual perception after one month of MFSCL Wear.