Effect of low-degree astigmatism on the objective visual quality

AIM:To evaluate the effect of low-degree astigmatism on objective visual quality through the Optical Quality Analysis System(OQAS).METHODS:This study enrolled 46 participants(aged 23 to 30y,90 eyes)with normal or corrected-to-normal vision.The cylindrical lenses(0,0.5,0.75,1.0,and 1.25 D)were placed at the axial direction(180°,45°,90°,and 135°)in front of the eyes with the best correction to form 16 types of regular low-degree astigmatism.OQAS was used to detect the objective visual quality,recorded as the objective scattering index(OSI),OQAS values at contrasts of 100%,20%,and 9%predictive visual acuity(OV100%,OV20%,and OV9%),modulation transfer function cut-off(MTFcut-off)and Strehl ratio(SR).The mixed effect linear model was used to compare objective visual quality differences between groups and examine associations between astigmatic magnitude and objective visual quality parameters.RESULTS:Apparent negative relationships between the magnitude of low astigmatism and objective visual quality were observed.The increase of OSI per degree of astigmatism at 180°,45°,90°,and 135°axis were 0.38(95%CI:0.35,0.42),0.50(95%CI:0.46,0.53),0.49(95%CI:0.45,0.54)and 0.37(95%CI:0.34,0.41),respectively.The decrease of MTFcut-off per degree of astigmatism at 180°,45°,90°,and 135°axis were-10.30(95%CI:-11.43,-9.16),-12.73(95%CI:-13.62,-11.86),-12.75(95%CI:-13.79,-11.70),and-9.97(95%CI:-10.92,-9.03),respectively.At the same astigmatism degree,OSI at 45°and 90°axis were higher than that at 0°and 135°axis,while MTFcut-off were lower.CONCLUSION:Low astigmatism of only 0.50 D can significantly reduce the objective visual quality.

Progression of Corneal Astigmatism after Phaco-Alternative at the University Hospital Center of the Oueme-Plateau Department in Porto-Novo

Objective: To study the postoperative evolution of corneal astigmatism following phaco-alternative at the University Hospital Center of Ouémé-Plateau (UHC-OP) in Porto-Novo. Method: This was a prospective, cross-sectional study with a descriptive and analytical purpose conducted from April 19 to September 20, 2021;a period of 6 months. The study included all patients presenting with senile or non-senile cataracts without a history of corneal trauma and who underwent phaco-alternative during the study period. Results: A total of 62 eyes underwent phaco-alternative. The average age was 63 ± 12 years with a male predominance of 59.7%. Phaco-alternative was performed with 74.2% linear incision and 25.8% smile incision. Perioperative incidents were mainly capsular ruptures with vitreous loss occurring in 8.1% of cases. The mean preoperative astigmatism was 1.29 ± 1.5 D with an axis of 180˚ ± 20˚, indicating with-the-rule astigmatism. The mean postoperative astigmatism was 2.2 ± 1.5 D with an axis of 90˚ ± 20˚, indicating against-the-rule astigmatism. The mean induced astigmatism at Day 30 was 1.4 ± 1.2 D for smile incision and 1.8 ± 1.2 D for linear incision. Conclusion: Phaco-alternative yields good results with few complications but remains astigmatogenic. The smile incision appears to be less astigmatogenic.

Surgical approaches to correct corneal astigmatism at time of cataract surgery: a mini-review

Among refractive errors,astigmatism is the most common optical aberration,where refraction changes in different meridians of the eye.It causes blurred vision at any distance and includes corneal,lenticular,and retinal astigmatism.Cataract surgery used to cause a progressive increase in the pre-exisiting corneal astigmatism because of creating a surgically induced astigmatism,for example,a large size surgery incision.The development of surgical techniques during last decades has made cataract surgery interchange to treat preoperative corneal astigmatism at time of surgery.Nowadays,three surgical approaches can be used.By placing a sutureless clear corneal incision on the steep meridian of the cornea,a preoperative corneal astigmatism less than 1.0 D can be corrected.Single or paired peripheral corneal relaxing incisions(PCRIs)provide 1.0-3.0 D corneal astigmatism correction.PCRIs are typically used for treating 1.0-1.5 D of regular corneal astigmatism,if more than 2.0 D,the risk of overcorrection and irregular astigmatism is increased.When toric intraocular lenses(IOLs)are unavailable in markets,PCRIs are still a reasonable option for patients with up to 3.0 D of pre-existing corneal astigmatism.Toric IOLs implantation can correct 1.0-4.5 D of corneal astigmatism.Several IOLs are approved to correct a high degree of corneal astigmatism with cylinder power up to 12.0 D.These approaches can be used alone or in combination.

Clinical Effect Analysis of Posterior Chamber Intraocular Lens Implantation for Correcting High Myopia and Astigmatism

Objective:To explore the corrective effect of posterior chamber intraocular lens implantation with phakic eyes in the treatment of high myopia and astigmatism.Methods:From May 2023,the hospital began to collect the case data of diagnosis and treatment of high myopia and astigmatism.By May 2024,310 cases were included,all of which were treated with posterior chamber intraocular lens implantation.The visual acuity,astigmatism and axial position of the intraocular lens were observed before and after treatment.Results:At different time points after the operation,the patient’s vision was significantly improved compared with that before the operation(P<0.05),and the vision level was equal to or greater than the best-corrected vision before the operation.At different time points after the operation,the average rotation of the intraocular lens was less than 5 degrees.Astigmatism was significantly lower than that before the operation(P<0.05).After the operation,the intraocular pressure increased in 11 cases,accounting for 3.55%,with no adverse complications such as lens turbidity,glare and obvious halo occurring.Conclusion:The posterior chamber intraocular lens implantation with phakic eyes has an ideal correction effect in the treatment of high myopia and astigmatism,which can effectively improve the vision level of patients and reduce the degree of astigmatism,and has high effectiveness and safety.

Symmetrical femtosecond laser arc incision in correcting corneal astigmatism in cataract patients

AIM:To evaluate the effect of symmetrical arc incision correcting corneal astigmatism in femtosecond laserassisted phacoemulsification(FLACS).METHODS:This study enrolled patients with cataract combined with regular corneal astigmatism of>0.75 D,who underwent FLACS.Symmetrical arc incision was set at 8 mm diameter and 85%depth.The follow-up time was 3-24mo(4.92±3.49mo).Pentacam recorded the corneal astigmatism and higher-order aberration at pre-operation and post-operation.The changes in corneal astigmatism were analyzed by Alpins method.The correlation of astigmatism type,age,corneal horizontal diameter,corneal thickness,arc incision length,and correction index(CI)was analyzed,and the residual corneal astigmatism was compared with the residual whole eye astigmatism.RESULTS:Totally 79 patients(102 eyes)were enrolled,10 patients had corneal epithelial injury,1 patient occurred corneal epithelial hyperplasia.The corneal astigmatism was 1.23±0.38 D pre-operation,and decreased to 0.76±0.39 D post-operation(t=10.146,P=0.000).Corneal high-order aberration was 0.17±0.08μm pre-operation and 0.24±0.11μm post-operation(t=-5.186,P=0.000).The residual corneal astigmatism and residual whole eye astigmatism were no significant difference(t=-0.347,P=0.729).Using Alpin’s method,the following were determined:target-induced astigmatism(TIA)=1.23±0.38 D,surgeryinduced astigmatism(SIA)=0.77±0.45 D,difference vector(DV)=0.77±0.39 D,and CI=0.54±0.28.Age,astigmatism size,corneal horizontal diameter,corneal thickness,and arc incision length were not correlated with CI.The CI for against the rule astigmatism(ATR)was better than that for with the rule astigmatism(WTR;P=0.001).CONCLUSION:Femtosecond laser-assisted astigmatic keratotomy has better CI of ATR,but increase higher-order corneal aberration.CI is not ideal,it’s not a perfect choice if we pursue ideal correction effect.

Case Report: Observation of Postoperative Refractive Status of Glaucoma Combined with Cataract and Irregular Astigmatism

Significance: So far, many scholars have studied the astigmatism caused by glaucoma surgery, but they cannot provide enough useful help for the clinic. When a patient has glaucoma, cataracts and irregular astigmatism at the same time, it is often difficult to achieve satisfactory results. Purpose: This study intends to describe a case of a patient with glaucoma, irregular astigmatism, and cataract who was successfully treated. Additionally, it can serve as a useful source of inspiration for the future care of patients like this. Case Presentation: A 24-year-old male with keratoconus in the past. He had undergone a corneal crosslinking operation in the right eye and a penetrating keratoplasty in the left eye due to his long history of keratoconus in both eyes. Right now, the keratoconus in that eye is stable. Unfortunately, he has now been diagnosed with open-angle glaucoma and complicated cataracts in both eyes, and he was admitted to our hospital for surgery. The right eye had significant irregular astigmatism, which was discovered during the preoperative assessment, and the implantation of a Toric intraocular lens was unable to produce good results. Finally, we chose to perform EXPRESS glaucoma drainage device implantation + phacoemulsification + intraocular lense (ZEISS CT ASPHINA 409MP) implantation. The patient had stable postoperative astigmatism with rule thanks to the traction effect of the scleral flap suture. Astigmatism was typically stable six months after surgery, and the corrected visual acuity with glasses had improved to 20/25. Conclusion: This patient suffers from cataracts, keratoconus, glaucoma, and irregular astigmatism. Due to the interconnectedness of these four disorders, simultaneous success is challenging. We realized that surgically induced astigmatism, frequently affects vision early after filtering surgery for glaucoma patients. In the instance of this patient, we tightly sutured the scleral flap and using tractive action, established regular astigmatism. After the patient’s astigmatism stabilized, optometry was given to correct the vision. This technique should result in much better visual acuity. Finally, it came to pass.

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.

Comparison of non-cycloplegic photorefraction,cycloplegic photorefraction and cycloplegic retinoscopy in children

AIM: To compare the results of noncycloplegic photorefraction, cycloplegic photorefraction and cycloplegic refraction in preschool and non-verbal children.METHODS: One hundred and ninety-six eyes of 98children(50 females, 48 males) were included in the study. Firstly, non-cycloplegic photorefraction was achieved with Plusoptix A09; secondly, cycloplegic photorefraction was carried out with Plusoptix A09 after10 min cyclopentolate. Finally, 30 min after instillation of twice cyclopentolate, cycloplegic refraction was obtained with autorefraction and/or standard retinoscopy. Spheric equivalent, spheric power, cylindric power and cylindrical axis measurements were statistically compared.RESULTS: The mean age was 28.8±18.5mo(range12-72mo). The differences in spherical equivalent, spheric power and cylindrical power measured by the three methods were found statistically significant(P 【0.05).The spherical equivalent and spheric power measured by cycloplegic photorefraction were statistically higher than the measurements of the other methods(P 【0.05). The cylindrical power measured by cycloplegic refraction was statistically lower than the measurements of the photorefraction methods(P 【0.05). There was no significant difference in cylindrical axis measurements between three methods(P 】0.05).CONCLUSION: For the determination of refractive errors in children, the Plusoptix A09 measurements give incorrect results after instillation of cyclopentolate.Additionally, the cylindrical power measured by Plusoptix A09 with or without cycloplegia is higher. However, the non-cycloplegic Plusoptix A09 measures spheric equivalent and spheric power similar to cycloplegic refraction measurements in preschool and non-verbal children.

Clinical evaluation of surgery-induced astigmatism in cataract surgery using 2.2 mm or 1.8 mm clear corneal micro-incisions

AIM： To evaluate corneal astigmatism after phacoemulsification using 2.2 mm or 1.8 mm clear corneal micro-incisions and its effects on visual function.METHODS： Sixty cases （60 eyes） with cataract were randomly divided into groups A （n=30） and B （n=30） respectively underwent 2.2 mm and 1.8 mm clear corneal tunnel incision phacoemulsification combined with folding intraocular lens implantation from the time direction of 11：00. On day 1 and at 1, 4, and 6wk after operation, patients’ vision was measured and both the corneal curvature and corneal thickness （CT） were recorded using Pentacam.RESULTS： The measured surgery-induced astigmatism （SIA） in both groups A and B peaked on day 1 after operation, and then gradually decreased and eventually stabilized in week 4. No statistically significant difference was found in corneal astigmatism between two groups （P〉0.05）. The measured corneal astigmatism at 4wk and 6wk postoperatively were 0.28±0.09 D and 0.27±0.10 D for groups A and 0.27±0.09 D and 0.25±0.10 D for groups B without statistically significant difference （P〉0.05）. In addition, no significant differences in visual acuity and CT were found between groups A and B before or after operation.CONCLUSION： Both 2.2 mm and 1.8 mm micro-incision cataract surgeries result in relatively small SIA with no difference in visual function and corneal astigmatism between two surgery approaches. Thus, the two types of surgical systems are safe and efficient for cataract treatment, by which satisfactory uncorrected visual acuity can be regained early postoperatively.

Comparison of the Retinomax hand-held autorefractor versus table-top autorefractor and retinoscopy

AIM:To compare noncycloplegic and cycloplegic results of Retinomax measurements with findings achieved after cycloplegia using table-top autorefractor and retinoscopy.METHODS:The study included 127 patients(mean age96.7mo,range 21 to 221).Retinomax(Rmax)(Nikon Inc.,Japan)was used to obtain noncycloplegic refraction.Under cycloplegia,refraction was measured with Rmax,table-top autorefractor(TTR)(Nikon NRK 8000,Inc.,Japan)and retinoscopy.The values of sphere,spherical equivalent,cylinder and axis of cylinder were recorded for Rmax,TTR and retinoscopy in each eye.All results were analyzed statistically.RESULTS:The mean spheric values(SV),spherical equivalent values(SEV)and cylindrical values(CV)of the noncycloplegic Rmax(SV:0.64 D,SEV:0.65 D and CV:0.03 D,respectively)were found to be significantly lower than cycloplegic TTR(1.43 D,1.38 D and 0.3 D;P=0.012,P=0.011 and P=0.04,respectively)and retinoscopy(1.34 D,1.45 D and 0.23 D;P=0.04,P=0.002 and P=0.045,respectively).Mean cycloplegic SV,SEV,CV were not significantly different between Rmax and TTR,Rmax and retinoscopy,TTR and retinoscopy.Cycloplegic or noncycloplegic axis values were not different between any method.CONCLUSION:Rmax may be used successfully as a screening tool but may not be accurate enough for actual spectacle prescription.Cycloplegic Rmax measurements may be able to identify refractive error in children because of approximate results to retinoscopy.

Correction of low corneal astigmatism in cataract surgery

· AIM: To evaluate and compare aspheric toric intraocular lens(IOL) implantation and aspheric monofocal IOL implantation with limbal relaxing incisions(LRI) to manage low corneal astigmatism(1.0-2.0 D) in cataract surgery.· METHODS: A prospective randomized comparative clinical study was performed. There were randomly recruited 102 eyes(102 patients) with cataracts associated with corneal astigmatism and divided into two groups. The first group received toric IOL implantation and the second one monofocal IOL implantation with peripheral corneal relaxing incisions. Outcomes considered were: visual acuity, postoperative residual astigmatism, endothelial cell count, the need for spectacles, and patient satisfaction. To determine the postoperative toric axis, all patients who underwent the toric IOL implantation were further evaluated using an OPD Scan III(Nidek Co, Japan). Follow-up lasted 6mo.· RESULTS: The mean uncorrected distance visual acuity(UCVA) and the best corrected visual acuity(BCVA) demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up the UCVA was statistically better in the patients with toric IOL implants compared to those patients who underwent implantation of monofocal IOL plus LRI. The mean residual refractive astigmatism was of 0.4 D for the toric IOL group and 1.1 D for the LRI group(P 【0.01). No difference was observed in the postoperative endothelial cell count between the two groups.· CONCLUSION: The two surgical procedures demonstrated a significant decrease in refractive astigmatism. Toric IOL implantation was more effective and predictable compared to the limbal relaxing incision.

Effect of the posterior corneal surface on total corneal astigmatism in patients with age-related cataract

AIM： To explore the effect of the posterior astigmatism on total corneal astigmatism and evaluate the error caused by substituting the corneal astigmatism of the simulated keratometriy （simulated K） for the total corneal astigmatism in age-related cataract patients. METHODS： A total of 211 eyes with age-related cataract from 164 patients （mean age： 66.8±9.0y, range： 45-83y） were examined using a multi-colored spot reflection topographer, and the total corneal astigmatism was measured. The power vector components J0 and J45 were analyzed. Correlations between the magnitude difference of the simulated K and total cornea astigmatism （magnitude differenceSimK-Tca）, anterior J0, and absolute meridian difference （AMD） between the anterior and posterior astigmatisms were calculated. To compare the astigmatism of the simulated K and total cornea both in magnitude and axial orientation, we drew double-angle plots and calculated the vector difference between the two measures using vector analysis. A corrective regression formula was used to adjust the magnitude of the simulated K astigmatism to approach that of the total cornea. RESULTS： The magnitude differenceSimK-Tca was positively correlated with the anterior corneal J0 （Spearman’s rho= 0.539; P〈0.001） and negatively correlated with the AMDR （Spearman’s rho=-0.875, P〈0.001）. When the anterior J0 value was larger than 1.3 D or smaller than -0.8 D, the errors caused by determining the total corneal astigmatism with the karatometric calculation tended to be greater than 0.25 D. An underestimation by 16% was observed for against the rule （ATR） astigmatism and an overestimation by 9% was observed for with the rule （WTR） astigmatism when ignoring the posterior measurements. CONCLUSION： Posterior corneal astigmatism should be valued for more precise corneal astigmatism management, especially for higher ATR astigmatism of the anterior corneal surface. We suggest a 9% reduction in the magnitude of the simulated K in eyes with WTR astigmatism, and a 16% addition of the magnitude of the simulated K in eyes with ATR astigmatism.

Non-cycloplegic spherical equivalent refraction in adults:comparison of the double-pass system,retinoscopy,subjective refraction and a table-mounted autorefractor

AIM:To evaluate the accuracy of spherical equivalent(SE) estimates of a double-pass system and to compare it with retinoscopy,subjective refraction and a table mounted autorefractor.METHODS:Non-cycloplegic refraction was performed on 125 eyes of 65 healthy adults(age 23.5±3.0 years) from October 2010 to January 2011 using retinoscopy,subjective refraction,autorefraction(Auto kerato refractometer TOPCON KR-8100,Japan) and a double pass system(Optical Quality Analysis System,OQAS,Visiometrics S.L.,Spain).Nine consecutive measurements with the double-pass system were performed on a subgroup of 22 eyes to assess repeatability.To evaluate the trueness of the OQAS instrument,the SE laboratory bias between the double pass system and the other techniques was calculated.RESULTS:The SE mean coefficient of repeatability obtained was 0.22D.Significant correlations could be established between the OQAS and the SE obtained with retinoscopy(r=0.956,P【0.001),subjective refraction(r=0.955,P【0.001) and autorefraction(r=0.957,P【0.001).The differences in SE between the double-pass system and the other techniques were significant(P【0.001),but lacked clinical relevance except for retinoscopy;Retinoscopy gave more hyperopic values than the double-pass system-0.51±0.50D as well as the subjective refraction-0.23±0.50D;More myopic values were achieved by means of autorefraction 0.24±0.49D. CONCLUSION:The double-pass system provides accurate and reliable estimates of the SE that can be used for clinical studies.This technique can determine the correct focus position to assess the ocular optical quality.However,it has a relatively small measuring range in comparison with autorefractors(-8.00 to +5.00D),and requires prior information on the refractive state of the patient.

Comparison of myopia control between toric and spherical periphery design orthokeratology in myopic children with moderate-to-high corneal astigmatism

AIM： To compare clinical results between toric and spherical periphery design orthokeratology（ortho-k） in myopic children with moderate-to-high corneal astigmatism. METHODS： This retrospective study enrolled 62 eyes of 62 subjects using toric ortho-k lenses. These subjects were assigned to the toric group. Based on the one-to-one match principle（same age, proximate spherical equivalence and corneal astigmatism）, 62 eyes of 62 subjects were enrolled and included in the spherical group. At one-year followup visit, visual acuity, corneal astigmatism, treatment zone decentration, axial elongation and adverse reaction were compared between these two groups. RESULTS： At the one-year visit, corneal astigmatism was significantly lower in the toric group（1.22±0.76 D） than in the spherical group（2.05±0.85 D）（P=0.012）. The mean magnitude of the treatment zone decentration was 0.62±0.42 mm in the toric group and 1.07±0.40 mm in the spherical group（P=0.004）. Axial elongation was significantly slower in the toric group（0.04±0.13 mm） than in the spherical group（0.09±0.13 mm）（P=0.001）. The oneyear axial elongation was significantly correlated with initial age（r=-0.487, P〈0.001） and periphery design of ortho-k lens（r=0.315, P〈0.001）. The incidence of corneal staining was lower in the toric group（8.1%） than in the spherical group（19.4%）（P〈0.001）. CONCLUSION： Toric periphery design ortho-k lenses may provide lower corneal astigmatism, better centration, slower axial elongation and lower incidence of corneal staining in myopic children with moderate-to-high corneal astigmatism.

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).

Combination of Toric and multifocal intraocular lens implantation in bilateral cataract patients with unilateral astigmatism

AIM： To assess the binocular visual function in bilateral cataract patients with unilateral astigmatism after combined implantations of Toric with multifocal intraocular lens （IOL）, and to compare with that of Toric and monofocal IOL implantation.METHODS： All the 30 patients with unilateral astigmatism suffered bilateral cataract were randomly divided into two groups： Toric plus multifocal IOL group and Toric plus monofocal IOL group. Uncorrected and corrected visual acuity at distance （5.0 m）, intermediate distance （0.6 m）, and near （0.33 m）, contrast sensitivity, and stereopsis were assessed 6mo after surgery. Patients were also surveyed for visual disturbances and spectacle dependence.RESULTS： Binocular uncorrected visual acuity （LogMAR） of Toric/multifocal IOL eyes at distance, intermediate, near were 0.05±0.05, 0.24±0.10, and 0.14±0.06 respectively. The values of Toric plus monofocal IOL eyes were 0.06±0.07, 0.26±0.08, and 0.37±0.10 respectively. These values did not indicate significant differences between two groups with exception of near visual acuity. In the photopic condition （with or without glare）, the contrast sensitivity of multifocal IOL eyes was significant lower than the monofocal IOL eyes in 18 cpd. In the mesopic condition, the contrast sensitivity of multifocal group was significant lower than monofocal group in 12 cpd, and in mesopic glare condition, this significant difference was found both in 6 cpd and 12 cpd. The stereopsis of Toric/multifocal IOL eyes decreased slightly （100±80 seconds of arc, t=2.222, P=0.136）. Mean near vision for patient satisfaction was statistically significantly higher in Toric/multifocal IOL group patients versus than that in Toric/monofocal IOL group （80% vs 25.5%, P=0.000）. Visual disturbance was not noticed in either group.CONCLUSION： Although the combination of Toric and multifocal IOL implantation results in compromising stereoacuity, it can still provide patients with high levels of spectacle freedom and good overall binocular visual acuity.

Validity of autorefractor based screening method for irregular astigmatism compared to the corneal topography-a cross sectional study

AIM：To present a method of screening for irregular astigmatism with an autorefractor and its determinants compared to corneal topography.METHODS：This cross-sectional validity study was conducted in 2013 at an eye hospital in Spain.A tabletop autorefractor（test 1）was used to measure the refractive status of the anterior surface of the cornea at two corneal meridians of each eye.Then corneal topography（test 2）and Bogan’s classification was used to group eyes into those with regular or no astigmatism（GRI）and irregular astigmatism（GRII）.Test 1 provided a single absolute value for the greatest cylinder difference（Vr）.The receiver operating characteristic（ROC）were plotted for the Vr values measured by test 1 for GRI and GRII eyes.On the basis a Vr value of 1.25 D as cut off,sensitivity,specificity were also calculated.RESULTS：The study sample was comprised of 260 eyes（135 patients）.The prevalence of irregular astigmatism was 42%[95%confidence interval（CI）：36,48].Based on test 2,there were 151 eyes in GRI and 109 eyes in GRII.The median Vr was 0.75 D（25%quartile,0.5 D）for GRI and1.75 D（25%quartile,1.25 D）for GRII.The area under curve was 0.171 for GRI and 0.83 for GRII.The sensitivity of test I was 78.1%and the specificity was 76.1%.CONCLUSION：A conventional autorefractor can be effective as a first level screening method to detect irregular corneal astigmatism in places where corneal topography facilities are not available.

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.

Corneal topographic changes and surgically induced astigmatism following combined phacoemulsification and 25-gauge vitrectomy

AIM： To evaluate corneal topographic changes and surgically induced astigmatism （SIA） after combined phacoemulsification and 25-gauge transconjunctival sutureless vitrectomy （25-G TSV）.METHODS： A retrospective study on 96 eyes of 87 patients who underwent combined phacoemulsification and 25-G TSV. The different topographic parameters and SIA were analyzed pre- and postoperatively.RESULTS： There was no significant changes in corneal topographic parameters at different follow up periods. Only surface regularity index changed significantly in the 2nd postoperative week and then returned to baseline values thereafter. Mean SIA gradually decreased to reach 0.12 D by the 6th postoperative month.CONCLUSION： Corneal surface and astigmatic changes are insignificant in either early or late postoperative periods following combined phacoemulsification and 25-G TSV. The SIA was the minimum among previous reports on sutureless vitrectomy alone or combined with phacoemulsification. Improvement of SIA did not stop at the 3rd postoperative month but it continued till the 6th month postoperatively.

CLINICAL ANALYSIS OF EXCIMER LASER PHOTOREFRACTIVE KERATECTOMY FOR TREATMENT OF MYOPIA AND MYOPIC ASTIGMATISM

To evaluate the efficacy and accuracy of photorefractive keratectomy (PRK) for myopia and myopic astigmatism .SVS APEX excimer laser with a wave length of 193 nm(Sumit Technology Inc. Waltham, Mass, USA) was applied. 316 myopic eyes of 168 patients were treated with PRK between September, 1996 and October, 1997, and 260 eyes (84%) of 150 patients were followed for more than three months, including male 68(116 eyes, 401%) and female 82(144 eyes, 599%). The preoperative spherical equivalent refractive errors ranged from -125D to -1000 (mean -467163D), and astigmatism ranged from 0 to -200D (means -033045D). We divided the patients into two groups according to the referaction: group A (from -125D to -590D) and group B(from -600 to -1000D). The number of eyes in the two groups were 220 and 40 respectively. In group A, on the 10th day, 689% has the uncorrected visual acuity (UCVA) equal to or one line better or lower than the preoperative best corrected visual acuity (BCVA). In 1,3,6 and 12 months, 90 %, 96%, 95% and 94% had the UCVA equal to or one line better or lower than the preoperative BCVA respectively. In group B, on the 10 th day, in 1,3,6 and 12 months, UCVA equal to or one line better or lower than the preoperative BCVA occurred in 359%, 83%, 87%, 86%, and 84% of the cases respectively. Most of the haze showed 051 grades except 3 eyes with the haze of 2 grade in 3 or 6 months and it changed to 1 and 05 grade respectively within one year. In 10 days and 1,3,6,12 months postoperatively, the corneal haze was noted in 329%, 848%, 628%,90% and 28% of the treated eyes respectively. We found that 193 nm excimer laser PRK was a predictable, safe, stable, and effective refractive surgery for correcting myopia up to -1000D in Chinese patients, and the effect was better in myopia lower than -600D.