Preoperative Astigmatism Research Articles

Comparative study of surgically induced astigmatism in superior and temporal scleral incisions in manual small-incision cataract surgery patients

Background: The purpose of the study is to evaluate surgically induced corneal astigmatism and visual outcome in patients undergoing small-incision cataract surgery (SICS) by modifying incision site on the basis of type of regular astigmatism. Material and Methods: This is a prospective study including 100 patients, having senile immature cataract, divided in two groups of 50 patients each according to the type of preoperative corneal astigmatism over a period of January 2018 to June 2019. A detailed preoperative evaluation was done including automated refractokeratometry, on the basis of which patients having steeper vertical axis (90° ±30°), i.e., “with the rule” astigmatism placed in Group A and subjected to superior SICS, and those having horizontal steeper axis (150°–180° and 0°–30°), i.e., “against the rule” astigmatism, were placed in Group B and subjected to temporal SICS. All surgeries were performed by a single ophthalmic surgeon with a similar technique of a 6.00 mm superior or temporal scleral straight incision. Surgically induced astigmatism (SIA) was calculated by a computer application SIA calculator version 2.0 on the 45th postoperative day and compared. Results: Present study showed mean SIA was significantly less in the temporal group (1.09 ± 0.42 D) as compared to the superior group (1.38 ± 0.62 D). Conclusion: Modification of incision site in SICS as per preoperative astigmatism produces comparable results to other sophisticated techniques such as phacoemulsification, and hence, it provides an alternative path to attain better visual outcome and reduced SIA with limited resources available in most of the developing countries.

Surgically induced astigmatism following femtosecond laser-assisted cataract surgery compared with conventional phacoemulsification

ObjectiveIn the present study, we reviewed surgically induced astigmatism (SIA) in femtosecond laser-assisted cataract surgery (FLACS) compared with conventional phacoemulsification in patients who have cataract.BackgroundTo assess SIA following clear corneal incisions created manually or with the Catalys femtosecond laser.Patients and methodsIn the present study, patients undergoing FLACS or manual cataract surgery between 2017 and 2019 from a single surgical center in Egypt were considered for inclusion. Postoperative corneal astigmatism values were compared with preoperative astigmatism indices to determine the SIA at 3 months postoperatively using the Alpins vector method.ResultsRefractive and topographic outcomes from 80 eyes of 40 patients (40 eyes in the manual group and 40 eyes in the FLACS group) were included. There was no significant difference in SIA (manual: 0.96 D and FLACS: 0.72 D) after 3 months postoperatively.ConclusionsThere was no significant difference in SIA between FLACS and manual cataract surgery after 3 months of surgery.

Residual astigmatism following cataract surgery

Objective: To determine the amount of residual astigmatism following cataract surgery.
 Materials and methods: A hospital based observational study was conducted in a tertiary eye hospital, Bangladesh during the period of July, 2013 to June, 2014. Patients was selected for the study who diagnosed as ARC with variable amount of astigmatism (1.5 to 3.5D), and excluded any other ocular pathology or history of previous ocular surgery. Phacoemulsification with PC Toric IOL implantation in all cases. Auto refracto-keratometer was done Preoperative and postoperatively for assessing the astigmatism. Main outcome measured were included preoperative uncorrected visual acuity, postoperative uncorrected visual acuity on 1stPOD, after 1 week and 1month, Preoperative keratometry, Preoperative astigmatism, Postoperative uncorrected keratometry on 1st POD, after 1 week and 1month, Postoperative uncorrected astigmatism on 1stPOD, after 1 week and 1month
 Results: 30 eyes of 28 patients were assessed in this study. Due to clear corneal incision during phacoemulsification, the steep meridian became flat significantly from pre-operative keratometry 44.329±1.473D (mean±SD) to 30thpost operative keratometry 43.971±1.431D (mean±SD) having p<0.001. On the other-hand the flat meridian became steeper from pre-operative keratometry 42.225±1.471D (mean±SD) to 30thpost operative keratometry 42.421±1.501D (mean±SD) having p<0.001. Preoperative mean astigmatism [Mean±SD] was 2.104±0.319D, after the first postoperative day, mean astigmatism decreased to 0.954±0.494D with p<0.01, and finally after 1 Month there was significant reduction of pre-operative astigmatism to 0.583±0.413D with p<0.0001. So, the mean pre-operative astigmatism decreased significantly in the successive post-operative days.
 Conclusion: Toric Intraocular lens implantation in phacoemulsification surgery can correct pre-existing corneal astigmatism significantly after one month of surgery.
 AKMMC J 2022; 13(1) : 42-46

Preliminary Characterization of Predictive Factors of the Visual Change after Epi-On and Epi-Off Corneal Collagen Crosslinking Techniques.

Purpose To investigate the potential predictive factors of the visual change achieved with accelerated epi-on and epi-off corneal collagen crosslinking (CXL) in keratoconus. Methods This retrospective comparative study analyzed 67 eyes treated with an accelerated epithelium-on (epi-on group) and epithelium-off (epi-off group) CXL. The clinical outcomes were evaluated and compared during a 1-year follow-up. Likewise, the relationship of the change achieved with both CXL techniques in the corrected distance visual acuity (CDVA) with different preoperative data was investigated. Results The mean CDVA change at 3 months postoperatively was −0.04 ± 0.19 and −0.07 ± 0.25 in the epi-on and epi-off groups, respectively (p = 0.809). In the epi-on group, this change was significantly correlated with the preoperative apical (r = −0.375, p = 0.045) and central corneal thickness (r = −0.402, p = 0.031). In the epi-off group, the CDVA change was significantly correlated with not only the preoperative apical (r = 0.402, p = 0.028) and central corneal thickness (r = 0.367, p = 0.046) but also with some topometric and aberrometric indices (r ≤ −0.374, p ≤ 0.042). Furthermore, the change in CDVA in the epi-on group could be predicted from age, preoperative refractive astigmatism J45 component, anterior corneal asphericity, and posterior corneal high order aberration root mean square (p = 0.002, R2 = 0.503). In the epi-off group, the CDVA change could be predicted from the preoperative minimum corneal thickness and magnitude of the vertical anterior corneal primary coma component (p = 0.001, R2 = 0.446). Conclusions Clearly, different predictive factors of the visual change induced with the accelerated epi-on and epi-off CXL techniques are present, suggesting a different mechanism of action for stiffening the cornea and inducing changes in this structure.

Refractive outcomes of femtosecond laser-assisted cataract surgery with arcuate keratotomy and standard phacoemulsification with toric intraocular lens implantation.

Femtosecond laser arcuate keratotomy (FS-AK) and toric intraocular lens (IOL) implantation are effective for the correction of eyes with corneal astigmatism. In this study, the postoperative refractive outcomes of patients receiving femtosecond laser-assisted cataract surgery (FLACS) with FS-AK and patients receiving standard phacoemulsification with toric IOL implantation were evaluated. This retrospective study reviewed the postoperative outcomes of patients undergoing FLACS with FS-AK (the FS-AK group) and patients undergoing standard phacoemulsification with toric IOL implantation (the toric IOL group). The main outcome measures were uncorrected and corrected visual acuities, keratometric and refractive astigmatism, and vector analysis. The FS-AK group included 41 eyes with preoperative keratometric astigmatism of - 1.64 ± 0.42 diopters (D), and the toric IOL group included 53 eyes with preoperative keratometric astigmatism of - 2.29 ± 0.91 D (P < 0.001). Postoperative refractive astigmatism was comparable between the two groups. Compared with the FS-AK group, postoperative uncorrected visual acuity was significantly better (P = 0.005) and corrected visual acuity was marginally better in the toric IOL group (P = 0.051). The absolute angles of error were 9.95° ± 9.57° and 5.08° ± 4.94° (P = 0.02) in the FS-AK and the toric IOL groups, respectively. Both FLACS with FS-AK and standard phacoemulsification with toric IOL implantation are safe and effective methods for astigmatism correction during cataract surgery. Standard phacoemulsification with toric IOL implantation achieves better visual acuity than FLACS with FS-AK at the 6-month follow-up.

The Influence of Analysis Mode Selection on Prediction Accuracy of Corneal Astigmatism Using Pentacam.

Purpose: To evaluate the influence of analysis mode selection on prediction accuracy of corneal astigmatism using Pentacam.Methods: Fifty-nine eyes of 59 patients implanted with toric intraocular lenses (IOLs) were included in the retrospective study. Preoperative corneal astigmatism (total refractive power) measured with Pentacam was analyzed based on 2-, 3-, 4-, or 5-mm ring or zone mode either centered on corneal apex or pupil center. Actual corneal astigmatism was calculated based on residual astigmatism on the corneal plane, surgical-induced astigmatism, and effective toric power on the corneal plane. Prediction error, the difference between actual corneal astigmatism and measured astigmatism, was compared among different analysis modes. Influences of local topography on prediction error were also evaluated.Results: Based on the zone mode, prediction error was lower when centered on corneal apex than on pupil center at different diameters, whereas based on the ring mode, this difference was only seen at 2-mm cornea (all P < 0.05). When centered on the corneal apex, the zone mode showed lower prediction error than the ring mode at 4- and 5-mm corneas (both P < 0.001), regardless of asymmetric or symmetric astigmatism. In symmetric bowtie, the zone mode showed lower prediction error than the ring mode at 2-mm cornea of the small bowtie, and 4- and 5-mm corneas of the large bowtie (all P < 0.05).Conclusions: For toric IOL planning, the corneal apex may be a better reference center. At a cornea diameter ≥4 mm, the zone mode is more accurate than the ring mode. Local topography affects prediction accuracy in the symmetric bowtie.

A study on corneal astigmatism before and after pterygium excision

The prevalence of pterygium shows a substantial increase for increasing age and UV irradiation. There is paucity of available literature regarding the total area of pterygium, percentage of extension of pterygium on to the cornea and its effects on corneal astigmatism. Hence this study was undertaken to evaluate the pre and post-surgical effect of the size of the pterygium on corneal astigmatism. 100 out patients aged between 22 to 50 years diagnosed with pterygium were included in the study. Slit lamp bio microscope was used to measure the length and width of pterygium in millimetres. Slit beam was used to measure the diameter of cornea. Corneal astigmatism was measured pre and postoperatively on day 1 and 1 month follow up using keratometery. In this study 2.13±1.39 was the mean preoperative astigmatism, 1.36±1.03 was the mean post-operative astigmatism on day 1 and on 1 month follow up 0.86±0.91 was the mean post-operative astigmatism which was statistically significant(p&amp;#60;0.001)). The corneal astigmatism was directly proportional to pterygium area. As the area of pterygium increased the post-operative astigmatism significantly decreased. There was increase in corneal astigmatism with the increase in the percentage of pterygium extension onto cornea. In post-operative period the corneal astigmatism decreased with the increase in the percentage of pterygium extension onto cornea (p&amp;#60;0.001). As per our findings we draw a conclusion that surgical removal of pterygium significantly reduces pterygium induced astigmatism and also there is an improvement in visual acuity.

Paired Opposite 4 mm Clear Corneal Incisions on Steep Meridian during Phacoemulsification.

Purpose:To evaluate the effect of opposite clear corneal incisions (OCCI) with 4 mm incisions on the steep meridian on postoperative astigmatism.Methods:This study was performed on 64 eyes of 55 patients with keratometric astigmatism of ≥ 1 diopter (D) undergoing phacoemulsification. Patients were divided into two groups, with-the-rule (WTR) astigmatism and against-the-rule (ATR) astigmatism. Initial incisions in the WTR group were performed on the temporal side with 3.2 mm keratome and paired stab incisions were performed on the steep meridian. At the end of the surgery, stab incisions were enlarged to 4 mm. Follow-up visits were scheduled at 1, 3, 6, and 12 months postoperatively, which included refraction and keratometry.Results:It was found that the mean preoperative keratometric astigmatism was 2.06 ± 0.86 D. The postoperative mean keratometric astigmatism was 1.3 ± 0.7 D after 1 month and 1.2 ± 0.7 D after 12 months. The mean astigmatism correction between the preoperative measure and that taken at 1 month was statistically significant (P = 0.001), but there was no significant change in the severity of astigmatism afterward. The mean surgically-induced astigmatism was found to be 1.99 ± 0.9 D. The 12-month changes of mean absolute astigmatism were: 1.06 ± 0.7 D in the WTR group, and 0.53 ± 0.7 D in the ATR group. The difference between the two groups was statistically significant (P = 0.02).Conclusion:Based on our findings, we posit that paired OCCI on the steep axis, using 4 mm incisions is an effective technique to correct preoperative astigmatism.

Refractive and keratometric outcomes of supervised novice surgeon-performed limbal relaxing incisions: 1-year results.

To report refractive and keratometric astigmatism outcomes of resident-performed limbal relaxing incisions (LRIs) during cataract surgery. Tertiary care academic teaching hospital. Retrospective case series. The length, location, and number of LRIs were determined preoperatively using an online calculator. Variables studied were preoperative keratometry and postoperative uncorrected and corrected distance visual acuity, refraction, and keratometry at 1-month, 3-month, and 12-month visits (POM1, POM3, and POM12, respectively). Subgroup analysis was performed on amount and type of astigmatism. The astigmatism double-angle plot tool and analysis of with-the-wound (WtW) and against-the-wound (AtW) changes were used to assess the effect of astigmatism correction at POM1, POM3, and POM12 visits. In 118 eyes, a higher percentage of eyes demonstrated refractive astigmatism 0.25 diopter (D) or less, 0.50 D or less, 0.75D or less, and 1.0 D or less at POM1 and POM12 (all P < .05) compared with preoperative keratometric astigmatism. Subgroup analysis showed improvement in all groups and types of astigmatism (P < .01). Patients achieved a statistically significant reduction of keratometric astigmatism at POM1, POM3, and POM12 (all P ≤ .0001) relative to baseline, and changes differed significantly based on the preoperative amount of astigmatism (all P ≤ .0001, with greater reductions associated with higher baseline astigmatism) but not by location of the steep meridian. There were significant WtW-AtW changes at POM1, POM3, and POM12. Regression of effect after 1 month was approximately 0.11 D. Resident-performed LRIs achieved effective and sustained reduction of both refractive and keratometric astigmatism regardless of meridian or magnitude of astigmatism for at least 1 year postoperatively.

Accuracy of Total Corneal Power Calculation for Multifocal Toric Intraocular Lens Implantation: Swept-Source OCT-Based Biometer vs Scheimpflug Tomographer.

To evaluate the accuracy of total corneal power calculation from a swept-source optical coherence tomography-based biometer and a rotating Scheimpflug tomographer for the Acrysof IQ Panoptix toric TFNT intraocular lens (IOL) (Alcon Labroatories, Inc). A retrospective study was undertaken on 145 eyes implanted with the TFNT IOL. The accuracy of total corneal power calculation from a SS-OCT-based biometer (IOLMaster 700; Carl Zeiss Meditec AG; total keratometry [TK]) and a rotating Scheimpflug tomographer (Oculus Optikgeräte GmbH; total corneal refractive power at 3 mm [TCRP3] and at 4 mm [TCRP4]) were compared. The surgically induced astigmatism vector, difference vector, angle of vector, correction index, index of success, coefficient of adjustment, and flattening index were analyzed using the VectrAK analysis program (ASSORT). The index of success showed a significant difference between the three methods (P = .035, analysis of variance test). The mean ± standard deviation of the index of success was the best in TK (0.43 ± 0.20), followed by TCRP4 (0.47 ± 0.24, P = .400, Bonferroni HSD test) and TCRP3 (0.50 ± 0.22, P = .030, Bonferroni HSD test). The preoperative refractive astigmatism prediction error was within ±0.50 diopters (D) in 62 eyes (42.8%) when using TCRP4 and in 66 eyes (45.5%) when using TK. These study results suggest that the refractive accuracy of TFNT implantation using total corneal power from TCRP4 and TK was favorable. [J Refract Surg. 2021;37(10):686-692.].

Effect of Opposite Clear Corneal Incision (CCI) on Corneal Higher-Order Aberrations after Phacoemulsification

Abstract Background: Nowadays, care of a cataractous patient greatly exceeds surgical removal of the opacified lens. In a step foreword to welfare of the elderly, phacoemulsification can perform as a refractive tool, addressing both spherical and astigmatic refractive errors. Aim of Study: The aim of that work was to evaluate safety and effectiveness of OCCIs, as an innovative procedure for correction of corneal astigmatism, during phacoemulsification. Patients and Methods: The study assessed 64 patients, who underwent phacoemulsification. Pre-operative and post-operative corneal topography was done, documented and statistically analyzed for each patient. Results: The study revealed a decrease of pre-operative corneal astigmatism from a pre-operative mean of –1.78D to a post-operative mean of 1.09D in OCCI group and a decrease of pre-operative corneal astigmatism from a pre-operative mean of –1.71D to a postoperative mean of 1.29D in single incision group. Conclusion: The present study revealed that OCCIs with appropriate pre-operative corneal topography represent a real advance in the applications of refractive lenticular surgery. OCCIs provide an innovative technique for managing pre-operative, regular, corneal astigmatism. This is simple, easy to learn technique, with no extra instrumentation. The OCCIs in this study was safe, with no wound related complications. However, OCCIs require careful early post-operative care, due to their penetrating nature. Once the wounds are sealed, risk of further complications approaches zero. Further studies on that technique, employing different incision architecture are required to help development of nomograms correlating the incision length, width, age of the patient, and the amount of pre-operative corneal astigmatism to be corrected.

Effect Of Trabeculectomy On Ocular Biometry And Refractive Errors In Pediatric Glaucoma

Background: Pediatric glaucoma triggers refractive errors by modifying the biometry of the eye. This study was conducted with the objective of estimating the short-term biometric and refractive changes prior to and post trabeculectomy in pediatric glaucoma. Material and Methods: A 12-month, descriptive, cross-sectional study was carried out from January to December 2019, using patients operated on for pediatric glaucoma. Pre- and post-operative biometric and refraction measurements were noted. Visual acuity, axial length, corneal diameter and refraction were obtained. All ethical requirements (anonymity, free, informed, and continuous consent) were satisfied. Data analysis was done using SPSS 20.0. Results: In the present study, 47 eyes of 27 patients were surgically operated upon, from January 2019 to December 2019 at CHU-IOTA. The predominant sex was male (17 patients) at 63%, giving a sex ratio (M / F) of 1.7. The mean age was 5.04 ± 4.24. Preoperatively, the mean corneal diameter, and D90 were respectively 13.83 ± 1.51 and 12.55 ± 0.99. Preoperatively, the mean axial length, and D90, were 23.87 ± 1.29 and 22.28 ± 1.07, respectively. Preoperatively and at three month, the mean myopia (n = 36), were respectively -3.13 ± 1.83 and -1.59 ± 0.97. The mean preoperative astigmatism (n = 47) and D90 were respectively, -1.59 ± 0.77 and -1.23 ± 0.57. A statistically significant relationship (p &lt;0.05) was found to exist between the preoperative and postoperative data of the axial length, corneal diameter, and refractive errors. Conclusions: Trabeculectomy significantly exerts a short-term positive impact on the biometrics and refraction by modifying the initial measurements and diopters.

Changes in corneal curvature and visual acuity in North Indian adults after pterygium excision with modified sutureless, glueless limbal-conjunctival autograft.

Purpose:To identify the exact time point during after following pterygium excision with a modified technique of sutureless, glueless limbal-conjunctival autograft, when stabilization of the change in corneal curvature is achieved; correlate size of pterygium with uncorrected visual acuity and astigmatism at baseline, and assess changes in these parameters postoperatively over time.Methods:This prospective study longitudinally assessed 30 eyes of 30 north Indian adults with primary pterygium encroaching upon ≥1 mm of the cornea pre- and postoperatively at 1 week and then monthly for 4 months, recording uncorrected (UCVA) and best-corrected logMAR visual acuity, astigmatism and keratometry. Results were analyzed using ANOVA, Mauchly’s test of sphericity with Greenhouse–Geisser correction, and post-hoc test using Bonferroni correction. Pearson’s correlation coefficient r > 0.5 was considered clinically significant, and P < 0.05 statistically significant.Results:Pterygium size was well correlated with pre-operative astigmatism (r = 0.867, P < 0.001) and pre-operative UCVA (r = 0.856, P < 0.001). There was mean improvement of 0.43 logMAR units of visual acuity (P < 0.00001), a mean increase of 0.79D of keratometric value for the flatter meridian (P < 0.00001) and a mean reduction of 2.00D of astigmatism (P < 0.00001). At 2-month follow-up, the keratometric value for the flatter meridian approached the final keratometric reading at 4 months such that the difference was not significant (t = 1.185, P = 0.245). There were no significant complications or recurrence during the follow-up period.Conclusion:Pterygium excision with modified autograft reduced corneal astigmatism and improved visual acuity comparable to classical technique. Alteration in corneal curvature stabilizes 2 months after surgery, when spectacle correction can be given to patients.

Incisional correction of corneal astigmatism during ‎phacoemulsification – a randomized trial

Background: Phacoemulsification is regarded as a type of refractive surgery by which it is possible to ‎reduce pre-existing corneal stigmatism.‎ This study aimed to evaluate the efficacy and safety of on-axis corneal incision with or without opposite clear corneal incisions (OCCI) to correct preoperative corneal astigmatism during uncomplicated phacoemulsification ‎surgeries.‎ Methods: A randomized, prospective, parallel two-arm interventional study, which included a ‎total 40 eyes from 40 patients, was conducted.‎ Patients were divided into two groups: 20 patients as controls underwent phacoemulsification with on-axis incision (CCI group), and 20 patients underwent phacoemulsification with OCCI (OCCI group). Results: Mean astigmatic correction was significantly higher in the OCCI group (0.665 vs 0.265 diopters, p-value &lt;0.001), compared to the CCI group. Most of the parameters (surgical induced astigmatism, magnitude of error, and correction index) were significantly higher in the OCCI group compared to the CCI group (p-value &lt;0.01). There were no ‎incision-related complications. Conclusions: Both incisional methods are useful methods for correction of preoperative corneal ‎astigmatism but OCCIs correct a higher amount of astigmatism than the on-axis clear ‎corneal incision.‎ Registration: ClinicalTrials.gov NCT04418986 (05/06/2020).

Wave front aberrations induced from biomechanical effects after customized myopic laser refractive surgery in finite element model.

A customized myopic refractive surgery was simulated by establishing a finite element model of the human eye, after which we studied the wave front aberrations induced by biomechanical effects and ablation profile after wave front-guided LASIK surgery. Thirty myopia patients (i.e., 60 eyes) without other eye diseases were selected. Their ages, preoperative spherical equivalent, astigmatism, and wave front aberration were then obtained, in addition to the mean spherical equivalent error range - 4 to - 8D. Afterward, wave front-guided customized LASIK surgery was simulated by establishing a finite element eye model, followed by the analysis of the wave front aberrations induced by the surface displacement from corneal biomechanical effects, as well as customized ablation profile. Finally, the preoperative and induced aberrations were statistically analyzed. Comatic aberrations were the main wave front abnormality induced by biomechanical effects, and the wave front aberrations induced by the ablation profile mainly included coma and secondary coma, as well as sphere and secondary-sphere aberrations. Overall, the total high-order aberrations (tHOAs), total coma (C31), and sphere ([Formula: see text]) increased after wave front-guided customized LASIK surgery. According to our correlation analyses, coma, sphere, and tHOAs were significantly correlated with decentration. Additionally, the material parameters of ocular tissue were found to affect the postoperative wave front aberrations. When the material parameters of the sclera remained constant but those of cornea increased, the induced wave front aberrations were reduced. All biomechanical effects of cornea and ablation profile had significant effects on postoperative wave front aberrations after customized LASIK refractive surgery; however, the effects of the ablation profile were more notorious. Additionally, the characteristics of biomechanical materials have influence on the clinical correction effect.

Astigmatic correction of simultaneous femtosecond laser-assisted cataract surgery (FLACS) with intrastromal arcuate keratotomy (ISAK) versus Toric intraocular Lens Impantation with conventional phacoemulsification

BackgroundTo compare the efficacies in astigmatic correction of simultaneous femtosecond laser-assisted cataract surgery (FLACS) with intrastromal arcuate keratotomy (ISAK) versus toric intraocular lens (IOL) implantation with conventional phacoemulsification in moderate astigmatism.MethodsA retrospective chart review was conducted for patients who had undergone cataract surgery by one surgeon. We identified patients with preoperative corneal astigmatism from + 0.75 to + 2.00 diopters (D) who had undergone astigmatic correction with FLACS with ISAK or toric IOL implantation with conventional phacoemulsification. We measured the visual acuity, intraocular pressure, automated keratometer, manifest refraction, and topography preoperatively and 1-day, 1-month, 3-month, and 6-month postoperatively. The vector analysis of refractive astigmatism was performed.ResultsOf a total of 48 eyes of 48 patients, 27 eyes of 27 patients had FLACS with ISAK (AK group), and 21 eyes of 21 patients had conventional cataract surgery with toric IOL implantation (toric IOL group). Refractive astigmatism was significantly decreased in both groups. The mean preoperative and 6-month postoperative refractive astigmatism were 1.85 ± 1.07 and 0.99 ± 0.51 D, respectively, in the AK group (P = 0.028), and 1.84 ± 0.81 and 0.68 ± 0.21 D, respectively, in the toric IOL group (P < 0.001). There was no significant difference in refractive astigmatism between the two groups at 6-month postoperatively (0.99 ± 0.51 vs 0.68 ± 0.21 D, P = 0.057). At 6-month postoperatively, parameters for vector analysis of refractive astigmatism showed no statistical difference between the two groups. Corneal astigmatism was significantly decreased in the AK group. Corneal astigmatism from topography and the automated keratometer were significantly lower in the AK group 6-month postoperatively compared to toric IOL group (0.94 ± 0.40 vs. 1.53 ± 0.46 D, P = 0.018 for topography; and 0.98 ± 0.69 vs. 1.37 ± 0.41 D, P = 0.032 for the automated keratometer).ConclusionsFLACS with ISAK could be an effective procedure for reducing astigmatism as well as toric IOL implantation in cataract surgery.

Femtosecond LASIK for the correction of low and high myopic astigmatism.

Higher preoperative myopic astigmatism is associated with a higher probability of retreatment due to patient dissatisfaction as a result of residual cylindrical error. Nonetheless, retreatment is safe and the final clinical results are comparable to those of patients with lower preoperative astigmatism who were satisfied with the primary treatment. Our purpose is to compare the efficacy and safety of femtosecond LASIK (FS-LASIK) for the refractive correction of patients with low (<1.5 Diopters (D) versus high (≥1.5D) myopic astigmatism. Retrospective observational study of 841 eyes of 825 eligible patients treated with FSLASIK for the correction of simple or compound myopic astigmatism. Outcome measures included residual error, best corrected and uncorrected distance visual acuity (BCVA and UCVA), efficacy and safety 3months after the primary procedure or the retreatment. Of 841 eyes in total, 432 (51.37%) had <1.5D (Group 1) and 409 (48.63%) had ≥1.5D (Group 2) preoperative myopic astigmatism. The efficacy index of primary treatment was 0.94 ± 0.18 in Group 1 and 0.89 ± 0.22 in Group 2 (P = 0.001). Of 138 eyes (16.41%) that were retreated due to dis-satisfaction related to residual refractive error, 28 belonged to Group 1 (6.5%) and 110 (26.9%) to Group 2 (P <0.001). Following retreatment, small but statistically significant differences in the residual mean postoperative cylinder (-0.08 ± 0.24 vs -0.27 ± 0.46D, P = 0.001) and UCVA (1.11 vs 0.96, P = 0.0001) were detected for Groups 1 and 2, respectively. However, there were no statistically significant differences in the safety and efficacy indices. Following FS-LASIK, eyes with myopic astigmatism ≥1.5D have approximately four times more chances of undergoing retreatment due to dis-satisfaction caused by residual refractive error compared to eyes with myopic astigmatism <1.5D. However, the clinical results after retreatment are highly satisfactory and comparable in both groups.

A comparative study of post-operative astigmatism in superior versus superotemporal scleral incisions in manual small incision cataract surgery in a tertiary care hospital

Background: In developing countries, manual small incision cataract surgery is a better alternative and less expensive in comparison to phacoemulsification and thus the incision is an important factor causing high rates of postoperative astigmatism resulting into poor visual outcome. Thus, modifications to the site of the incision is needed to reduce the pre-existing astigmatism and also to prevent postoperative astigmatism. Modification to superotemporal incision relieves pre-existing astigmatism majorly due to its characteristic of neutralizing against-the-rule astigmatism, which is more prevalent among elderly population and thus improves the visual outcome. Aims: To study the incidence, amount and type of surgically induced astigmatism in superior and superotemporal scleral incision in manual SICS. Methodology: It is a randomized, comparative clinical study done on 100 patients attending the OPD of Ophthalmology at a tertiary care hospital, with senile cataract within a period of one year and underwent manual SICS. 50 of them chosen randomly for superior incision and rest 50 with superotemporal incision. MSICS with PCIOL implantation were performed through unsutured 6.5 mm scleral incision in all. Patients were examined post-operatively on 1st day, 7th day, 2nd week and 4th week and astigmatism was evaluated and compared in both groups. Results: It is seen that on postoperative follow up on 4th week, 77.78% of the patients with ATR astigmatism who underwent superior incision had increased astigmatism whereas, only 13.63% of the patients with ATR astigmatism who underwent supero-temporal incision, had increased astigmatism but 81.82% had decreased ATR astigmatism. However, 77.78% of the patients with preoperative WTR astigmatism who underwent supero-temporal incision, had increased astigmatism, whereas 44.45% of the patients with WTR astigmatism preoperatively, had increased astigmatism in contrast to 50% had decreased amount of astigmatism. It is also seen that the supero-temporal incision group had more number of patients (78%) with visual acuity better than 6/9 at 4th postoperative week than superior incision group (42%). Conclusion: This study concludes that superior incision cause more ATR astigmatism postoperatively whereas superotemporal incision causes lower magnitude of WTR astigmatism, which is advantageous for the elderly. Besides superotemporal incision provides better and early visual acuity postoperatively.

Toric Intraocular Lens Calculation Considering Anterior Surgically Induced Astigmatism and Posterior Corneal Astigmatism

ABSTRACT Purpose To evaluate the prediction error (PE) after applying the Abulafia–Koch formula in an online calculator with and without consideration of anterior corneal surgically induced astigmatism (SIACornea). Methods SIACornea models were calculated with a historical database of 204 right eyes (REs) from a single surgeon, either for manual (2.2 mm) or femtosecond (2.5 mm) temporal clear corneal incisions. PE was assessed in 58 REs operated by the same surgeon with a monofocal toric IOL and calculated, considering the PCA estimation in an online calculator with the combination of each one of the following SIACornea calculation approaches: (A) considering only significant centroids after stratification, (B) all centroids after stratification and (C) a single centroid without stratification. Results The consideration of all centroids resulted in an underestimation of SIACornea in cases of preoperative against-the-rule astigmatism (ATR-A) and an overestimation in with-the-rule astigmatism (WTR-A). After stratification, SIACornea was only significant in preoperative ATR and oblique astigmatism cases for femtosecond incisions. PE considering PCA only was 0.03@160º. The combination with SIACornea resulted in a WTR-A surprise in preoperative ATR-A and WTR-A, however only being significant for preoperative ATR-A in calculation approaches B (0.29@84º) and C (0.21@80º). SIACornea addition to PCA estimation only reduced the centroid for oblique preoperative astigmatism. Conclusions Surgeons should consider the calculation of the SIACornea after stratification by astigmatism type when using the same incision location (i.e. temporal). However, SIACornea derived from the anterior corneal surface should not be combined with PCA estimation for IOL power calculations.

High power custom toric intraocular lens for correcting high corneal astigmatism in post-keratoplasty and keratoconus patients with cataract.

Purpose:To analyze the outcomes of phacoemulsification with high power customized toric intraocular lens implantation (IOL) in patients with high corneal astigmatism (6-10 D Cyl) post keratoplasty and keratoconus eyes with cataract.Methods:Five eyes post keratoplasty with clear graft, four eyes with stable keratoconus, one eye with pterygium excision scar with visually significant cataract were included in this retrospective study. Phacoemulsification was done followed by implantation of custom made high power toric IOL in all patients. Outcomes included uncorrected and best-corrected distance visual acuity (UDVA, BCVA), pre-operative astigmatism at the corneal plane and IOL plane, post-operative residual astigmatism, mean torus of all IOLs used were calculated.Results:The minimum follow-up time was 12 months. At the last follow-up visit, there was a significant improvement (pre-operative vs post-operative) of UDVA (1.5 ± 0.47 vs 0.28 ± 0.14 logMAR; P < 0.05), cylindrical refraction (-9.0 ± 1.80 D vs - 1.1 ± 0.45 vs ; P < 0.05). Range of IOL powers used was 1.0-26.50 DSph and 9.0-15.5 DCyl. Post-operative mean residual spherical equivalent was 0.75 ± 0.5.Conclusion:This novel study describes the effectiveness of custom toric IOLs in high astigmatism in the range of 9.0-15.5 DCyl. Phacoemulsification with implantation of a customized high power toric IOL was effective in correcting high astigmatism in complex cases in our study.