Modification of contact lenses via metal-organic frameworks for glaucoma treatment

The prevention of blindness from glaucoma requires multiple treatments to lower intraocular pressure.Here,human contact lenses are modified with highly porous metal-organic frameworks with sustained release of brimonidine for prolonged glaucoma treatment.Various metal-organic frameworks were screened for their attachment to lenses,loading with brimonidine,and drug-release properties.Opti-mized therapeutic ocular lenses conjugated with MIL-101(Cr)frameworks maintain optical transparency and power.Coating of lenses with MIL-101(Cr)nanoparticles reduced brimonidine washout with tears and ensured a gradual and localized release of the drug into the eyeball through the cornea.The hybrid lenses provided a 4.5-fold better decrease in eye pressure,compared by area under the curve(AUC)value to a commercially available brimonidine tartrate solution.Therapeutic lenses did not induce any notable eye irritation or corneal damage in vivo.The newly devel-oped hybrid lenses are expected to provide a robust platform for the therapy and prevention of various ocular diseases.

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.

Objective assessment of the effect of pupil size upon the power distribution of multifocal contact lenses

AIM： To analytically assess the effect of pupil size upon the refractive power distributions of different designs of multifocal contact lenses.METHODS： Two multifocal contact lenses of center-near design and one multifocal contact lens of center-distance design were used in this study. Their power profiles were measured using the NIMO TR1504 device （LAMBDA-X, Belgium）. Based on their power profiles, the power distribution was assessed as a function of pupil size. For the high addition lenses, the resulting refractive power as a function of viewing distance （far, intermediate, and near） and pupil size was also analyzed.RESULTS： The power distribution of the lenses was affected by pupil size differently. One of the lenses showed a significant spread in refractive power distribution, from about ？3 D to 0 D. Generally, the power distribution of the lenses expanded as the pupil diameter became greater. The surface of the lens dedicated for each distance varied substantially with the design of the lens.CONCLUSION： In an experimental basis, our results show how the lenses power distribution is affected by the pupil size and underlined the necessity of careful evaluation of the patient’s visual needs and the optical properties of a multifocal contact lens for achieving the optimal visual outcome.

Endothelial parameters in central and peripheral cornea in patients wearing contact lenses

AIM： To measure the parameters of endothelium in the central and peripheral parts of the cornea and evaluate the influence of wearing the hard and soft contact lenses on the mentioned parameters.METHODS： A specular microscope was used to measure the corneal endothelium parameters in both eyes of 139 Caucasians（a total of 278）. All participants were divided into three groups： soft lens wearers, hard lens wearers and a control group. Factors, such as age, smoking, types of lens material, duration of lens wear and lens air permeability were assessed to determine their impact on the morphometric parameters of the endothelium.RESULTS： A lower percentage of hexagon-like cells and higher cell variation than in other groups were determined in hard contact lens wearers. The difference in density of endotheliocytes between the groups was not observed. The measurements of the morphometric parameters in soft contact lens wearers did not depend neither on the duration of lens wear, nor on air permeability. The relation between the patients＇ age and the variation of endothelium parameters was determined in the group of hard contact lens wearers.CONCLUSION： Wearing hard contact lenses provokes pleomorphism and polymegethism of the corneal endothelium, while soft contact lenses do not impact any parameters of the endothelium, most likely due to higher air permeability.

Application of Sodium Ion Sensor Based on the SnO_2/ITO Glass in the Detection of Rinsing Solution for Contact Lenses

This paper presents the studying results of the sodium ion sensor device based on the SnO_2/ITO glass structure in the detection of rinsing solution for contact lenses.The selective membrane contains poly (vinyl chloride) (PVC),bis (2-ethylhexyl) sebacate (DOS),(12-crown-4) methylmalonate (B12C4),and sodium tetrakis (4-fluoropbenyl) borate dehydrate (NaTFBD). The final weight ratios are PVC:DOS:B12C4:NaTFBD=33:66:2:2.In this condition,the sensor has performances with linear sensitivity,short response time,good repeatability and selectivity.The sensor was used to measure the rinsing solution for the contact lenses.Because the experimental results show close to the accurate value for four commercial products,this sensor can preliminary be used in detecting the rinsing solution for the contact lenses.Using this structure and sodium-sensing membrane to construct the sodium sensor is proven successfully in this application.

Comparison of efficacy of two different silicone hydrogel bandage contact lenses after T-PRK

AIM:To compare the efficacy between two different silicone hydrogel bandage contact lenses after transepithelial photorefractive keratectomy(T-PRK).METHODS:In this randomized controlled trial,a total of 89 patients(178 eyes) who underwent T-PRK at the Qingdao Eye Hospital from October to December 2019 were selected.One random eye wore a Senofilcon A bandage contact lens after surgery,and the other eye a Balafilcon A bandage contact lens.Pain scores,uncorrected visual acuity(UCVA),spherical equivalent(SE),corneal epithelial healing status,epithelial thickness,bandage lenses deposits,lenses movement,and ocular surface conditions were measured and compared.RESULTS:There were no differences between the two groups in UCVA,SE,corneal epithelial healing status,corneal epithelial thickness,tear river heights and tear film rupture time at each follow-up visit.However,postoperative pain scores in the Senofilcon A group were significantly lower than those of the Balafilcon A group(F_(intergroups)=67.833,P<0.001;F_(time)=383.773,P<0.001;F_(interaction)=57.344,P<0.001).The duration of pain in eyes in the Senofilcon A group was shorter than that of the Balafilcon A group(t=-3.326,P=0.001).The surface deposition scores and movement scores of Senofilcon A bandage lenses on the first and fourth days after surgery were lower than those of Balafilcon A bandage lenses(Z=-5.385,-6.782,P<0.001;Z=-8.336,-8.906,P<0.001).CONCLUSION:Both Senofilcon A and Balafilcon A bandage lenses have good efficacy after T-PRK.Senofilcon A lenses are associated with less pain and more comfort compared to Balafilcon A.

A case of severe refractive changes induced by Galyfilcon A silicone hydrogel contact lenses

Dear Sir, I＇m Boris Severinsky from the New England College of Optometry, Boston, USA. I write you to present an interesting case of extreme refractive and corneal topography changes induced by daily wearing of Acuvue Advance （Johnson＆Johnson, Vision Care） contact lens （CL）.

Clinic study on silicone hydrogel contact lenses used as bandage contact lenses after LASEK surgery

AIM: To compare the clinical performance of two types of silicon hydrogel contact lenses used as bandage lenses after LASEK surgery. METHODS: A prospective, double-masked study was conducted on 42 eyes of 21 patients who received binocular LASEK surgeries. The interocular difference in spherical equivalent power was less than -1.50D. Patients were randomly assigned to wear Galyfilcon A (Lens A) bandage contact lens in one eye and Balafilcon A (Lens B) in the fellow eye after the surgery. The responses to a subjective questionnaire on comfort of wearing, corneal epithelial status, conjunctival hyperemia, limbal neovascularization, lens fitting and contact lens debris were assessed 1 and 5 days postoperatively. Corneal endothelium was assessed before and 5 days after the surgery upon bandage lens removal. RESULTS: There was no difference between the two groups in terms of conjunctival hyperemia, limbal neovascularization, contact lens fitting, corneal epithelial status, corneal endothelium cell density (CD) and endothelium cell size (CS) at any postoperative visit. Complaints of discomfort, including foreign body sensation, pain and intolerance were statistically more among Lens B wearers at any postoperative visit (P < 0.05). Lens B appeared to attract much more debris than Lens A at the 5-day post-operative follow-up visit (P < 0.01). CONCLUSION: The two types of silicon hydrogel lenses investigated in this study demonstrated similar clinical performance in terms of corneal responses and lens fitting. However, Lens A showed a better performance in terms of comfort of wearing and deposit resistance.

Aberration changes of the corneal anterior surface following discontinued use of rigid gas permeable contact lenses

AIM: To record aberrations with a corneal topographic device on the anterior surface of the cornea at different time-points prior to wearing and following discontinued use of rigid gas permeable (RGP) contact lenses. The effect of wearing RGP on the anterior surface of the cornea was discussed to provide guidance for clinical refractive error correction.METHODS: The study objects were 24 eyes from 24 patients. All patients underwent identical examination procedures prior to lens use, as well as afterwards, including slit-lamp examination, non-contact tonometer measurement, computer optometry and corneal curvature measurement, subjective refraction test, and corneal topography analysis. The patients wore contact lenses everyday for 1 month and then discontinued. Corneal topographies were recorded at certain time points of 30 minutes, 1 day, 3, 7 and 14 days following use.RESULTS: Total corneal aberration at each time point following discontinued use of RGP contact lenses was less than the time point prior to use. Detailed results were as follows: root mean square (RMS) (pre)=(1.438± 0.328)μm, RMS (30 minutes) =(1.076 ±0.355)μm, RMS (1 day) =(1.362 ±0.402)μm, RMS (3 days) =(1.373 ±0.398)μm, RMS (7 days) =(1.387 ±0.415)μm, and RMS (14 days) = (1.430±0.423)μm. Results showed that at 30 minutes after discontinued use of RGP contact lenses, almost all 2 ndand 3 rd-order aberrations change. Quadrafoil Z10 and spherical Z12 of the 4 th-order were also changed. Alterations to Z5, Z6, and Z12 at 1 day after discontinued use were significant differences compared with the time period prior to RGP use: Z5 and Z6 decreased, and Z12 increased slightly. Z5 and Z6 remained decreased at 3 days after discontinued use, but Z9 and Z10 continued to increase and Z12 returned to levels prior to RGP use. At 14 days after discontinued use, all aberrations were notsignificantly different from the values prior to use.CONCLUSION: The use RGP contact lenses greatly reduced total aberration of the anterior surface of the cornea. Changes to 2 ndand 3 rd-order aberrations (including Z3, Z4, Z5, Z6, Z7, and Z8) were more significant. Following discontinued use of RGP contact lenses, the majority of lower order aberrations returned to original levels in a short period of time. During this process, a transient higher order aberration appeared, but all changes disappeared within 14 days after discontinued use of RGP contact lenses.

Enhanced drug loading efficiency of contact lenses via salt-induced modulation

Low drug loading efficiency is one of the main obstacles hindering the application of contact lenses(CLs) as the carrier for extended ocular drug delivery. Here in this study, a simple and effective drug loading method based on salt induced modulation was proposed and demonstrated with mechanism elucidation. First of all, using poly(2-hydroxyethyl methacrylate)(p-HEMA) as the contact lens material, betaxolol hydrochloride, Diclofenac Sodium and Betaxolol Base as the model drugs with different solubility, influence of salt concentration,salt type(sodium salts of sulfate, chloride, and sulfocyanate) and drug properties in the loading solution on drug loading efficiency was investigated. Mechanism of enhanced drug loading in contact lens was further explored via studying the influence of salt on the absorption isotherm, drug solubility and water content of CLs. Applicability of this method to other CLs materials was also investigated. It was demonstrated that adjusting the ionic strength of loading solutions resulted in significant increase of drug loading in CLs. Type and concentration of the salts and solubility of the drug were the main factors influencing enhancement ratio of drug loading. The mechanism for improved drug loading was related to the reduced drug solubility in loading solutions and the reduced bound water content in contact lenses. Modulation of drug loading by adjusting ionic strength was also applicable to other CLs and the light transmittance was not affected. This method was more suitable for salt-form drugs with high solubility. In summary, adjusting ionic strength of loading solution is an economical and effective way to improve drug loading in CLs, and this simple method may also find application in other hydrogel based drug delivery systems.

Evaluation of the safety and efficacy of therapeutic bandage contact lenses on post-cataract surgery patients

AIM： To evaluate the safety of therapeutic bandage contact lens for post-cataract surgery patients and to illustrate its efficacy on post-operative comfort and tear-film stability. METHODS： A total of 40 participants were recruited and randomly divided into two groups. Group one was instructed to wear bandage contact lenses for a week and use antibiotic eye drops for a month since the first day after surgery. Group two received sub-conjunctival injection of tobramycin and was asked to wear eye pads on the first day after surgery and then were instructed to use antibiotic eye drops as the first group did. Ocular surface disease index（OSDI） questionnaire, slit-lamp microscope examination of tear break-up time（TBUT）, corneal fluorescein score（CFS）, tear meniscus height（TMH） together with anterior segment optical coherence tomography（AS-OCT） and corneal topography were evaluated preoperatively and postoperatively. RESULTS： The subjective feeling（P=0.004）, TBUT（P〈0.001） and TMH（P=0.02） post-surgery had improved in patients who used bandage contact lenses compared with those who did not at 1wk post-surgery. Until three month postoperatively, the comfort degree（P=0.004） and TMH（P=0.01） of group two were still worse than group one. Moreover, TBUT（P〈0.001） and CFS（P=0.004） of the group with eye pads got worse than the results before, whereas the group with bandage contact lenses recovered to normal. None of these patients had infections or other complications. CONCLUSION： Wearing therapeutic bandage contact lens after cataract surgery, compared with traditional eye-pads, is a safe method to improve tear-film stability and reduce post-operative discomfort without hindering corneal incision recovery.

Evaluation of refractive correction for standard automated perimetry in eyes wearing multifocal contact lenses

AIM：To evaluate the refractive correction for standard automated perimetry（SAP）in eyes with refractive multifocal contact lenses（CL）in healthy young participants.METHODS：Twenty-nine eyes of 29 participants were included.Accommodation was paralyzed in all participants with 1%cyclopentolate hydrochloride.SAP was performed using the Humphrey SITA-standard 24-2 and 10-2 protocol under three refractive conditions：monofocal CL corrected for near distance（baseline）;multifocal CL corrected for distance（m CL-D）;and m CL-D corrected for near vision using a spectacle lens（m CL-N）.Primary outcome measures were the foveal threshold,mean deviation（MD）,and pattern standard deviation（PSD）.RESULTS：The foveal threshold of m CL-N with both the24-2 and 10-2 protocols significantly decreased by 2.2-2.5 d B（P〈0.001）,while that of m CL-D with the 24-2 protocol significantly decreased by 1.5 d B（P=0.0427）,as compared with that of baseline.Although there was no significant difference between the MD of baseline and m CL-D with the24-2 and 10-2 protocols,the MD of m CL-N was significantly decreased by 1.0-1.3 d B（P〈0.001）as compared with that of both baseline and m CL-D,with both 24-2 and 10-2 protocols.There was no significant difference in the PSD among the three refractive conditions with both the 24-2 and 10-2 protocols.CONCLUSION：Despite the induced mydriasis and the optical design of the multifocal lens used in this study,our results indicated that,when the dome-shaped visual field test is performed with eyes with large pupils and wearing refractive multifocal CLs,distance correction without additional near correction is to be recommended.

Is the Use of Empirically Designed Custom Soft Contact Lenses a Good Option for Challenging Patients?

Purpose: Reasons for the lack of success for contact lens patients range from poor fit, to discomfort or to a less than optimum wearing schedule. This project was a preliminary investigation of customized soft toric contact lenses as an alternative for unsuccessful contact lens patients or potential drop-outs. Methods: Fifteen healthy non-compromised, previously unsuccessful contact lens wearing patients (13 women, 2 men) with ages from 21 to 33 years (25.1 ± 2.7 years) were the subjects for this study. They were empirically fitted with 15 astigmatic and 5 spherical customized SpecialEyes soft contact lenses. Visual acuities, comfort, lens movement, and rotation were evaluated. Results: Patients fitted with customized SpecialEyes soft contact lenses had statistically significant better visual acuities than with Phoropter Manifest Refraction. The lenses used in this study centered well and moved no more than 1 mm upon each blink. Lens rotation was less than 10 degrees for all toric lenses. Patients gave very positive vision and comfort ratings. Conclusion: This preliminary study supports the application of a software program to empirically design and manufacture Special Eyes custom soft lenses based upon corneal topographical parameters and subjective manifest refraction for those patients who either have challenging corneal parameters, high sphero-cylindrical prescriptions, or are currently dissatisfied with their contact lenses and are potential drop-outs.

ZERNIKE ASTIGMATISM AND VISUAL PERFORMANCE IN MYOPIC EYES BY RIGID GAS PERMEABLE CONTACT LENSES WEAR

To investigate the effects of rigid-gas-permeable contact lens(RGP-CL)wear on Zernike astigmatism and visual performance in myopic eyes.Methods:A wavefront sensor was used to evaluate Zernike astigmatism for 21 eyes with minimum astigmatism and 18 eyes with moderate astigmatism under three different modes of refractive correction:the RGP-CL,spectacle lens correcting spherical equivalent(SL)and spectacle lens fully correcting spherical error and astigmatism(fSL).Contrast visual acuity was assessed with a VA tester at four contrast levels and two luminance backgrounds.Results:Compared to the SL wear,RGP-CL wear changed the main axis astigmatism(Z_(2)^(2))from
0:09-0:34 to 0.34-0.22 for the minimum astigmatism group,while the contrast VA was improved about 0.05 LogMAR(F=8:06,p<0:01).For the group with moderate astigmatism,significant reduction in Z_(2)^(2)was found for both fSL wear(t=4:78,p<0:001)and RGP-CL wear(t=6:29,p<0:0001).The changes in astigmatism were significantly correlated between the fSL and RGP-CL wears(r=0:897,p<0:0001 for Z_(2)^(-2);and r=0:643,p=0:004 for Z_(2)^(2)).Contrast VA was significantly improved for both fSL and RGP-CL wears and the improvements were significantly correlated between each other for all four contrast levels and two backgrounds.Conclusion:RGP-CL wear induces astigmatism for the eyes with minor astigmatism probably due to a correction of corneal astigmatism and thus a manifesting of the lens astigmatism.For the astigmatic eyes,RGP-CL wear has similar effect on correcting astigmatism as the spectacle lens wear with spherical-cylinder correction and also produces similar visual improvement.

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.

Corneal Wavefront Aberrations in Patients Wearing Multifocal Soft Contact Lenses for Myopia Control

Purpose: The purpose of this study was to evaluate the change in corneal wavefront aberrations in young adults who have been fit with multifocal soft contact lenses for myopia progression control. Findings have been analyzed for statistical significance and clinical relevance and compared to reportedly successful Orthokeratology outcomes. Methods: The dominant eye of 40 participants (27 women, 13 men;mean age 27.3 ± 3.2 years;range 23 to 39 years) was fit with Proclear Multifocal center distance lenses (Coopervision, Pleasanton, USA) having a variety of distance powers and reading additions. Refractive errors were limited to a range of –6.00 D up to +1.00 D of sphere, and no greater than –1.00 D of cylinder. Corneal wavefront measurements were performed over 6 mm diameters with a Zeiss Atlas 9000 corneal topographer (Zeiss Meditec, Dublin, USA) prior to, and following lens fitting. Data were converted into rectangular Fourier optics terms M, J0, J45 and RMS values for each reading addition were statistically analyzed. Following evaluation of statistical significance and clinical relevance, results were compared to published data from successful Orthokeratology treatments. Results: Statistically significant changes in higher order aberrations were detected for lenses of all reading additions. Lens groups with higher Add-powers demonstrated stronger changes with increased significance. Final RMS values relating to 2nd, 3rd and 4th Zernike Orders reached clinical significance with a wavefront error of 0.10 μm, the equivalent of 0.25D. Moreover, as Add-powers increased, 3rd and 4th order aberrations likewise showed an increase. Pre-fitting astigmatism values accounted for the highest recorded aberrations and remained predominantly unchanged. Conclusion: Proclear Multifocal center-distance contact lenses were found to increase higher order wavefront aberrations in a manner dependent on their Add-power. In comparison to successful Orthokeratology outcomes, the amounts of resulting aberrations are notably different.

A survey of corneal changes caused by daily wear silicone hydrogel contact lenses

The examination of the effects of second generation lotra filcon B silicone hydrogel(SiH)lenses on the cornea when worn for three years of daily wear.Material and Methods:55 healthy patients were divided into two groups:current hydrogel contact lens wearers refitted with lotrafilcon B lenses(Group 1;28 patients)and neophyte contact lens wearers(Group 2;27 patients).Each patient's subjective eye comfort was measured with a self-administered questionnaire.The corneas were analyzed using contact specular microscope to measure corneal thickness and the endothelium before the SiH lenses werefitted after four weeks,one month,six months,one year,two years,and three years of lens wear.Results:Subjective complaints of patients in Group 1 were reduced;however patients in Group 2 experienced discomfort during the first two to four weeks of use.In Group 1,objective examinations identified a decrease in endothelial cell density.In Group 2,the endothelial cell density increased slightly in the first two years but decreased after three years.The results indicate that lotra filcon B slows down the deleterious effects of contact lenses.The coe±cient of variation significantly decreased after six months in Group 1(0.47 vs 0.44;p?0:049),whereas,in Group 2,the hexagonal cells improved significantly after one month(27.78 vs 28.25;p=0.025).Conclusion:Based on the subjects involved and the period of time under examination,it can be concluded that high-Dk SiH lenses support the physiological metabolism and functions of the cornea by improving oxygen provision.

Optical Modeling and Analysis of Peripheral Optics of Contact Lenses

Background: Degraded peripheral vision has been hypothesized to be a stimulus for the development of foveal refractive error. Contact lenses have been widely used to correct central vision, but their impacts on peripheral vision are still unknown. The purpose of this study was to use optical model software to evaluate the peripheral optics of rigid gas permeable (RGP) and soft contact lenses (SCLs) in isolation. This will better assist us in understanding their peripheral optical performances on human eyes. Methods: An optical design software package (Zemax EE) was used to model peripheral optics of Menicon RGP lens and Acuvue 2 SCLs. Profiles of sphero-cylindrical power and major higher-order aberrations were computed in 10osteps out to 40o off-axis eccentricity for –3.0 D central focal power contact lens. The results of optical modeling were analyzed and compared with previously published experimental data. Results: –3.0 D RGP lenses and SCLs had –1.4 D and –2.0 D dioptric power at 40o eccentricity, respectively. The reduced dioptric power in the periphery of the analyzed contact lenses quantitatively matched with the reduced amount of hyperopic field curvature found from experimental data when these contact lenses fitted on human eyes. Cylindrical power increased to 0.3 D ~ 0.4 D at 40o eccentricity for both lens types. In addition, both contact lens types produced higher order aberrations, namely 1.2 μm coma and 0.15 μm spherical aberration at 40o eccentricity. Conclusions: Compared to SCLs, RGP lenses with equal focal power had less dioptric power in the periphery. Both RGP lenses and SCLs produced the same amount of major higher-order aberrations with increasing of the field angle. Some of these results can be used to predict and understand the peripheral optical performance of contact lenses on human eyes.

Continuous Wear of Hydrogel Contact Lenses for Therapeutic Use

Purpose: To investigate the efficacy and complications of continuous wear of etafilcon A for therapeutic use. Materials and Methods: The subjects were 228 eyes of 219 outpatients prescribed contact lens (CL) for one week of continuous therapeutic wear during 10 years. The reason for prescription of CLs, the primary disease, the duration of CL wear and the complications were assessed retrospectively. Results: The predominant reason for prescription of CLs was relief of pain or a foreign-body sensation (62.3%) and protection of the corneal epithelium (20.6%). The primary disease was post-penetrating keratoplasty (36.8%), followed by corneal epithelial erosion (14.5%), post-lamellar keratoplasty (14.0%) and bullous keratopathy (12.2%). The average duration of wearing single lens was 6.5 ± 3.2 days. The average duration of wearing CLs in total was 9.2 ± 10.7 months. The most frequent problem associated with continuous wear of CLs was their dropping out of CLs (12.3%). The complications associated with CLs included conjunctivitis with papillary hyperplasia, corneal erosion and superficial punctate keratitis, but corneal ulcer and corneal infiltrates were not found. Conclusion: Serious complications were not shown changing the lenses every week to keep to the prescribed time limit for continuous therapeutic wear, even if corneal epithelial barrier function is impaired.

Long-term rotational stability and visual outcomes of a single-piece hydrophilic acrylic toric IOL:a 1.5-year follow-up

AIM：To evaluate the rotational stability and visual outcomes of a single-piece hydrophilic acrylic toric intraocular lenses（IOL） over a 1.5-year follow-up period.Data from the 6-month follow-up study have been previously reported.METHODS：Forty eyes of 26 cataract patients（mean age：72.8±7.9y） with pre-existing corneal astigmatism of 1.0 to 2.6 D were enrolled in the study.Mean axial length was 23.17±0.88 mm.Main outcome measures after implantation of the Torica-a A IOL（Human Optics） were IOL rotational stability,subjective refraction,astigmatism correction,uncorrected and corrected distance visual acuity（UDVA,CDVA）.RESULTS：There was no significant change in the parameters evaluated between the 6-month and 1.5-year follow-ups.At last visit,mean absolute IOL rotation（objective method） was 1.81°±1.87°（range 0.00° to 7.20°） with 78.6% of eyes having IOL rotation 〈3°,92.9% of eyes 〈5° and 100% of eyes 〈8°.No patient required secondary IOL repositioning during the course of the study.Mean residual refractive cylinder was-0.60±0.40 D.There was a significant reduction in the magnitude of the J0 vector postoperatively（P〈0.0001） with a mean absolute change of 0.76±0.40 D.The mean J45 vector was close to zero preoperatively and postoperatively and didn＇t change significantly（P=0.28）.Mean monocular UDVA and CDVA was 0.09±0.12 log MAR and-0.01±0.12 log MAR,respectively.No treatment with Nd：YAG laser was required.CONCLUSION：The Torica-a A IOL shows good and stable visual performance and rotational stability over a 1.5-year follow-up period.