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.

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.

Posterior corneal astigmatism modifications after cataract surgery and its role on total corneal astigmatism

Background:In recent years posterior corneal astigmatism and its effect on total corneal astigmatism has been studied,with research showing that this can impact total astigmatism.This study aims to ascertain if there is significant change in the posterior corneal astigmatism after cataract surgery and its impact on the total astigmatism.Methods:Analysis of 76 eyes that underwent cataract surgery with monofocal intraocular lens implantation.Corneal topography was performed with Pentacam(OCULUS®)pre-and post-operatively.Total corneal astigmatism was calculated with the algorithm of vergence tracing.We compared preoperative and postoperative changes in the magnitude and axis differences of anterior corneal curvature astigmatism,posterior corneal curvature astigmatism and the calculated total corneal astigmatism.We calculated the correlation between the total preoperative astigmatism and the difference between total corneal astigmatism and anterior corneal astigmatism.Results:The mean preoperative and postoperative posterior astigmatism was 0.31±0.02 D,showing no significant differences before and after surgery(P=0.989).Statistically significant differences between the calculated total corneal astigmatism and anterior corneal astigmatism were registered preoperatively and postoperatively in the with-the-rule anterior(WTR)corneal astigmatism(P=0.004,P<0.0001);against-the-rule(ATR)anterior corneal astigmatism(P<0.0001,P<0.0001)and in the oblique(P=0.026,P=0.019)subgroups.The posterior corneal astigmatism and the total corneal astigmatism correlated positively with the differences between the total corneal and anterior corneal astigmatism(R=0.378,P=0.001).Conclusions:There were statistically significant differences between the magnitude of the total astigmatism and anterior corneal astigmatism,underlining the impact of posterior corneal astigmatism.A positive correlation between the preoperative posterior astigmatism and the difference between the total corneal and the anterior corneal astigmatism suggests a specially relevant role of posterior corneal astigmatism when evaluating patients with higher degrees of astigmatism.

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.

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.

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.

Effect of femtosecond laser-assisted steepest-meridian clear corneal incisions on preexisting corneal regular astigmatism at the time of cataract surgery

AIM:To investigate the clinical efficacy and safety of femtosecond laser-assisted steepest-meridian clear corneal incisions for correcting preexisting corneal astigmatism performed at the time of cataract surgery.METHODS:This prospective case series study comprised consecutive age-related cataract patients with corneal regular astigmatism(range:+0.75 to+2.50 D)who had femtosecond laser-assisted steepest-meridian clear corneal incisions(single or paired).Corneal astigmatism was performed with the Pentacam preoperatively and 3 mo postoperatively.Total corneal astigmatism and steepestmeridian measured in the 3-mm central zone were used to guide the location,size and number of clear corneal incision.The vector analysis of astigmatic change was performed using the Alpins method.RESULTS:Totally 138 eyes of 138 patients were included.The mean preoperative corneal astigmatism was 1.31±0.41 D,and was significantly reduced to 0.69±0.34 D(equivalent to difference vector)after surgery(P<0.01).The surgically-induced astigmatism was 1.02±0.54 D.The correction index(ratio of target induced astigmatism and surgically-induced astigmatism:0.72±0.36)as well as the magnitude of error(difference between surgically-induced astigmatism and target induced astigmatism:-0.29±0.51)represented a slight under correction.For angle of error,the arithmetic mean was 1.11±13.70,indicating no significant systematic alignment errors.CONCLUSION:Femtosecond-assisted steepest-meridian clear corneal incision is a fast,customizable,adjustable,precise,and safe technique for the reduction of low to moderate corneal astigmatism during cataract surgery.

Case report:simultaneous femtosecond laser astigmatic keratotomy and toric intraocular lens implantation in femtosecond laser-assisted cataract surgery in a patient with surgically induced high corneal astigmatism

Background:Femtosecond laser astigmatic keratotomy(FSAK)and toric intraocular lens(IOL)implantation have been studied individually for comparison to treat astigmatism at cataract surgery.We report a case of surgically induced high corneal astigmatism by laser thermal keratoplasty(LTK)in a patient with cataract who was successfully treated with simultaneous combination of FSAK and toric IOL implantation with femtosecond laser-assisted cataract surgery(FLACS).This is the first report of both procedures combined simultaneously,with or without history of LTK.Case Description:A 68-year-old male presented with a history of LTK with two enhancements each eye in 2004,with subsequent surgically induced high corneal astigmatism,and with age-related nuclear cataract of both eyes.IOL master demonstrated+7.71 diopters of astigmatism at 163 degree right eye and+3.29 diopters of astigmatism at 4 degree left eye.After extensive discussion of the risks and benefits,the patient agreed to undergo FLACS with FSAK with two 61 degrees of relaxation incisions(RIs)and toric IOL(Alcon SN6AT9)right eye;FLACS with toric IOL(Alcon SN6AT7)alone left eye.At 2-year follow-up,uncorrected visual acuity was 20/30 right eye,20/25 left eye.His best corrected visual acuity was 20/25(+0.25+1.00 axis 21)right eye and 20/20(plano+0.25 axis 90)left eye;his best corrected near visual acuity was J1+with add+2.50 diopters right eye and left eye.Conclusions:Patients with age-related cataract and LTK induced high corneal astigmatism can hardly be sufficiently treated with FSAK or toric IOL alone at the time of cataract surgery.An effective way is to combine large FSAK and toric IOL of the highest cylindrical power of T9,in our case,simultaneously,which can achieve an excellent long term visual outcome.

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.

Surgical induced astigmatism correlated with corneal pachymetry and intraocular pressure: transconjunctival sutureless 23-gauge versus 20-gauge sutured vitrectomy in diabetes mellitus

AIM: To determine the difference of surgical induced astigmatism between conventional 20-gauge sutured vitrectomy and 23-gauge transconjunctival sutureless vitrectomy, and the influence of corneal pachymetry and intraocular pressure(IOP) on surgical induced astigmatism in diabetic patients.METHODS: This retrospective, consecutive case series consisted of 40 eyes of 38 diabetic subjects who underwent either 20-gauge or 23-gauge vitrectomy. The corneal curvature and thickness were measured with Scheimpflug imaging before surgery and 1wk; 1, 3mo after surgery. We compared the surgical induced astigmatism(SIA) on the true net power in 23-gauge group with that in 20-gauge group. We determined the correlation between corneal thickness change ratio, IOP and SIA measured by Pentacam. RESULTS: The mean SIAs were 1.082 ±0.085 D( mean ± SEM), 0.689 ±0.070 D and 0.459 ±0.063 D at postoperative 1wk; 1, 3mo respectively in diabetic subjects. The vitrectomy induced astigmatisms were declined significantly with time(F2,36=33.629, P =0.000)postoperatively. The 23-gauge surgery group induced significantly less astigmatism than 20-gauge surgery group(F1,37=11.046, P =0.020). Corneal thickness in diabetes elevated after surgery(F3,78=10.532, P =0.000).The linear regression analysis at postoperatively 1wk went as: SIA =-4.519 +4.931 change ratio(Port3) +0.026IOP(R2=0.46, P =0.000), whereas the rate of cornealthickness change and IOP showed no correlation with the change of astigmatism at postoperatively 1 and 3mo.CONCLUSION: There are significant serial changes in both 20-gauge and 23-gauge group in diabetic subjects.23-gauge induce less astigmatism than 20-gauge and become stable more rapidly than 20-gauge. The elevation of corneal thickness and IOP was associated with increased astigmatim at the early postoperative stage both in 23-gauge and 20-gauge surgery group.

Effects of posterior corneal astigmatism on the accuracy of AcrySof toric intraocular lens astigmatism correction

AIM：To evaluate the effects of posterior corneal surface measurements on the accuracy of total estimated corneal astigmatism.METHODS：Fifty-seven patients with toric intraocular lens（IOL） implantation and posterior corneal astigmatism exceeding 0.5 diopter were enrolled in this retrospective study.The keratometric astigmatism（KA） and total corneal astigmatism（TA） were measured using a Pentacam rotating Scheimpflug camera to assess the outcomes of AcrySof IOL implantation.Toric lOLs were evaluated in 26 eyes using KA measurements and in 31 eyes using TA measurements.Preoperative corneal astigmatism and postoperative refractive astigmatism were recorded for statistical analysis.The cylindrical power of toric lOLs was estimated in all eyes.RESULTS：In all cases,the difference of toric IOL astigmatism magnitude between KA and TA measurements for the estimation of preoperative corneal astigmatism was statistically significant.Of a total of 57 cases,the 50.88%decreased from Tn to Tn-1 and 10.53%decreased from Tn to Tn-2.In all cases,5.26%increased from Tn to Tn＋1.The mean postoperative astigmatism within the TA group was significantly lower than that in the KA group.CONCLUSION：The accuracy of total corneal astigmatism calculations and the efficacy of toric IOL correction can be enhanced by measuring both the anterior and posterior corneal surfaces using a Pentacam rotating Scheimpflug camera.

Influence of preoperative astigmatism on corneal biomechanics and accurate intraocular pressure measurement after micro-incision phacoemulsification

AIM: To define the corneal hysteresis(CH), corneal resistance factor(CRF), Goldmann-correlated intraocular pressure(IOPg) and corneal compensated intraocular pressure(IOPcc) prior to and following coaxial micro-incision phacoemulsification in patients with corneal astigmatism. METHODS: Of 97 patients with cataracts were enrolled in the study. Group 1 included patients with corneal astigmatism(K1-K2) values of K1-K2<+1.0 D, and group 2 with values of K1-K2 ≥+1.0 D and ≤+2.25 D. Coaxial micro-incision phacoemulsification of a corneal incision of 2.0 mm with intraocular lens(IOL) implantation was performed. CH, CRF, IOPg, IOPcc, waveform score(WS) were measured preoperatively and one week, one month postoperatively using an Ocular Response Analyzer. Axial length(AXL) was calculated by Tomey Optical Biometer OA 2000.RESULTS: Group 1 consisted of 51 patients with mean corneal astigmatism value of +0.49±0.25 D. Group 2 included 46 patients with astigmatism of +1.43±0.43 D. In group 1, CRF(t=2.68, P<0.05), CH(t=2.64, P<0.05) and WS(t=3.51, P<0.05) were significantly lower one week postoperatively, when compared to the preoperative values. CRF significantly decreased(t=3.61, P<0.05) when measured one month following the surgery. In group 2 CH(t=5.92, P<0.05), and WS(t=3.96, P<0.05) were significantly lowered one week after cataract surgery. Moreover, we observed a significant decrease in IOPg(t=2.24, P<0.05), CRF(t=5.05, P<0.05) and CH(t=2.31, P<0.05) one month after phacoemulsification. There was no statistically significant(t=-0.83, P=0.41) difference in AXL between study groups.CONCLUSION: CRF, CH and IOPg are reduced in patients with preoperative corneal astigmatism equal or higher than +1.0 D and lower than +2.25 D. Hence, bias of IOPg measurement in these patients may cause underestimation of the real IOP both before and after cataract surgery. The measurement of IOPcc allows the precise assessment of IOP pre-and postoperatively, independently on corneal astigmatism, CH and CRF values.

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.

Factors associated with corneal astigmatism change after ptosis surgery

AIM: To evaluate the predictive factors of postoperative corneal astigmatism change in ptosis patients who underwent ptosis surgical repair.METHODS: Patients who underwent levator resection at Oculoplastic service of the Department of Ophthalmology, Naresuan University Hospital, Thailand between September 2017 and August 2019 were retrospectively evaluated. Changes in degree and axis of corneal astigmatism after ptosis surgery were compared based on patient factors consisting of age at operation, sex, preoperative marginreflex distance(MRD) 1, and preoperative degree and axis of corneal astigmatism.RESULTS: Forty-two eyes of 28 patients were included in the study. Wilcoxon signed ranks test showed a significant postoperative corneal astigmatism change only in a subgroup of eyes with preoperative astigmatism of ≥1.5 diopters(D;P=0.006). Furthermore, 72.2%(13/18) of the eyes with preoperative astigmatism of ≥1.5 D showed a reduction of astigmatism after eyelid surgery, with the mean astigmatic change of 0.65 D. Majority of preoperative eyes demonstrated with-the-rule astigmatism pattern(45.2%), of which 57.9% showed a reduced degree of astigmatism.CONCLUSION: In patients undergoing ptosis surgery, the data demonstrate for the first time the association between postoperative corneal astigmatism change and a preoperative corneal astigmatism of ≥1.5 D. Thus, we encourage considering severity of corneal astigmatism prior to cataract or refractive surgery planning in ptosis patients, especially with toric-intraocular lens, to avoid the possibility of calculation error.

Objective visual quality one year after toric IOL implantation for correction of moderate and high corneal astigmatism

AIM:To compare the objective visual quality after implantation of a toric intraocular lens(IOL)in order to correct moderate or high corneal astigmatism at the one year postoperative follow-up.METHODS:From December 2017 to June 2018,66 patients(90 eyes)with simple age-related cataract with regular corneal astigmatism greater than 1.5 D were enrolled in this prospective self-control study.The patients were implanted with Proming?toric IOL(model:AT3 BH-AT6 BH).The subjects were divided into moderate astigmatism group(46 eyes,1.5-2.5 D)and high astigmatism group(44 eyes,>2.5 D).The uncorrected distance visual acuity,residual astigmatism and axial position of IOL were observed before operation,3,6 mo and 1 y after operation.Modulation transfer function cutoff(MTF cutoff),Strehl ratio(SR),object scatter index(OSI)were observed by OQAS II to evaluate the objective visual quality of patients.RESULTS:There was no significant difference in UCVA,residual astigmatism,axial deviation,MTF cutoff,SR and OSI between moderate and high astigmatism group(all P>0.05).After 3 mo,UCVA,MTF cutoff and SR were significantly increased(all P<0.05),residual astigmatism and OSI were significantly decreased(all P<0.05).After 3 mo,all the indexes remained stable.CONCLUSION:Proming toric IOL can effectively treat age-related cataract patients with moderate-to-high regular corneal astigmatism,correcting corneal astigmatism,improving UCVA,ensuring long-term stability in the capsule,and providing patients with better visual quality.

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.

Acute corneal graft rejection following photorefractive keratectomy for post-penetrating keratoplasty high astigmatism

Dear Editor,We present an unusual case of acute graft rejection after photorefractive keratectomy(PRK),performed to correct high residual astigmatism after penetrating keratoplasty(PKP)for keratoconus.The primary measures of success for PKP are visual acuity,refractive outcomes。

Spinocerebellar Ataxia with Oculomotor Apraxia and Severe Corneal Astigmatism

Purpose: To disclose the association between spinocerebellar ataxia with oculomotor apraxia and high grade (7 diopters) congenital astigmatism. Methods: Single observational case report. A 39-year-old patient affected by spinocerebellar ataxia from the age of 20 was submitted to genetic and ophthalmic investigations to reach a diagnosis. Results: Genetic testing did not lead to a sure diagnosis, while clinical and instrumental ophthalmic examinations pointed out an oculomotor apraxia and a congenital severe astigmatism. Conclusion: To conclude the eye movement recording permitted to identify an oculomotor apraxia in this case of spinocerebellar ataxia. This is the first report of severe astigmatism in cases of ataxia with oculomotor apraxia.

Effect of TICL implantation on corneal astigmatism and the stability and visual quality after operation

Objective:To explore the effect of TICL implantation on corneal astigmatism,postoperative stability and visual quality.Methods:110 patients(174 eyes)with high myopia and astigmatism who were treated with TICL implantation in our hospital from July 2016 to July 2018 were selected as the research subjects.The follow-up time was 12 months.The changes of UCVA,BCVA,and astigmatism values were used as indicators to evaluate the effectiveness of treatment.The diopter changes of the affected eye at different periods after surgery and the changes in the rotation angle of the intraocular lens axis at different periods after surgery were used as indicators to determine the stability of surgical treatment.Results:The UCVA and BCVA of the affected eyes after operation were significantly higher than those before operation(P<0.05).Compared with pre-operation,the diopter of the affected eyes was significantly reduced after operation(P<0.05);Based on the axial position of the intraocular lens on the first day after surgery,the degree of rotation of the intraocular lens implanted in the affected eyes was significantly reduced(P<0.05);Compared with pre-operation,there was no statistically significant difference in corneal endothelial cell count,intraocular pressure,and arch height after operation.Conclusion:Patients with high myopia and corneal astigmatism received TICL implantation after correction treatment,visual acuity was significantly improved,visual quality was significantly improved,with good postoperative stability,which had good clinical promotion value.

Toric Intraocular Lens Malposition Corrected by Lens Repositioning to Manifest Refractive Cylinder Axis in Patient with Irregular Astigmatism Due to Corneal Scar

A case is presented of a patient with an unexpected poor visual result and subsequent correction following cataract removal surgery via phacoemulsification and intraocular lens implantation using a toric intraocular lens implant (IOL). The initial operation resulted in an uncorrected vision of 20/100 (0.70 logMAR). Retrospective analysis of the patient’s corneal topography revealed irregular astigmatism secondary to remote trauma to the cornea. The cylinder axis on manifest refraction (MR) was significantly different from measured keratometry, so a second procedure was performed to align the cylinder axis of the IOL with the steep axis on MR. This repositioning procedure improved visual outcome to a final uncorrected vision of 20/25 (0.10 logMAR) and best corrected acuity of 20/20 (0.0 logMAR).