Residual Refractive Astigmatism Research Articles

Clinically relevant differences in the selection of toric intraocular lens power in normal eyes: preoperative measurement vs intraoperative aberrometry.

Purpose: To assess the value of intraoperative aberrometry (IA) in determining toric intraocular lens (IOL) power in eyes with no previous ocular surgery.Patients and methods: This was a retrospective data review at one US clinical site of eyes that underwent uncomplicated cataract surgery with toric IOL implantation where standard preoperative and IA measurements were available. Calculated IOL sphere and cylinder powers and orientation were compared based on the measurement method and the postoperative refraction, using both actual and simulated (back-calculated) results. Comparisons were between the surgeon’s preoperative calculations, IA measurements, the actual IOL implanted and results from the Barrett toric calculator.Results: There was no significant difference (p>0.7) in the number of eyes expected to have, or having, a spherical equivalent refraction within 0.50D of the target between Actual (92%), IA (93%) or Preoperative calculation results (86%). The percentage of eyes with expected residual refractive astigmatism ≤0.50D was significantly higher for the IA vs Preoperative calculations (75% vs 53%, p<0.01). There was no significant difference in expected results between the Actual, IA and Barrett toric calculations (p>0.65).Conclusion: Modern IOL calculations for sphere produced results comparable to those achieved with IA. The value of IA in determining IOL cylinder power and orientation was more evident when comparing expected results between IA and a preoperative method based on measured total corneal astigmatism than when comparing to expected results from the Barrett toric calculator.

Correcting astigmatism at the time of cataract surgery: Toric IOLs and corneal relaxing incisions planned with an image-guidance system and intraoperative aberrometer versus manual planning and surgery

To compare the outcomes of the combination of an image-guided system and intraoperative aberrometer with the surgeon's standard of care in correcting astigmatism using toric intraocular lenses (IOLs) or corneal incisions. Single site in United States. Prospective case series. Contralateral eyes of patients having uncomplicated bilateral cataract surgery and astigmatism correction were randomly assigned to Group A or Group B. Group A received the surgeon's preferred standard of care. Group B had preoperative planning using an image-guidance system (VERION), intraoperative aberrometry (ORA System with VerifEye+), and femtosecond laser-assisted cataract surgery. The primary endpoint was the residual refractive astigmatism at 3months. Thirty-eight eyes were treated with toric IOLs and 40 eyes with corneal astigmatic incisions. On average, toric IOLs resulted in almost 0.25 diopter (D) less cylinder than corneal astigmatic incisions (P<.01), with no difference between groups (P=.41). There was no statistically significant difference in the mean spherical equivalent refraction by group (P=.51). At 3months, the IOL in 4 eyes (11%) (2 in Group A and Group B each) was more than 10 degrees of absolute orientation from the intended orientation. The mean keratometry was 0.16 D higher with the image-guided system compared with optical biometry (Lenstar). The vector difference between the 2 measurements was 0.5 D or lower in all eyes. The combined use of an image-guided system and intraoperative aberrometer did not significantly improve outcomes compared with the surgeon's standard of care. Based on keratometry, there was good agreement in corneal astigmatism measurements between the image-guided system and the optical biometer.

Clinical Outcomes Using a Novel Image-Guided Planning System in Patients With Cataract and IOL Implantation

To determine the proportion of eyes with preexisting astigmatism achieving 0.50 diopters (D) or less of residual refractive cylinder 3 months after either implantation of toric intraocular lenses (IOLs) or corneal incisions using the VERION system (Alcon Laboratories, Inc., Fort Worth, TX) measurement module and digital markers for microscope (M) and laser (L). Eyes with preexisting astigmatism in the intention-to-treat population were divided into four groups. Eyes in the no laser treatment group underwent toric IOL implantation with the measurement module, vision planner, and digital marker M (n = 102). Eyes in the other three groups underwent implantation of toric (n = 110), monofocal (n = 88), or multifocal (n =100) IOLs using the measurement module, vision planner, and digital marker M, including digital marker L, and LenSx laser (Alcon Laboratories, Inc.). The proportions of eyes achieving 0.50 D or less of relative refractive cylinder and with manifest refraction spherical equivalent (MRSE) deviating 0.50 D or less from the target outcome were evaluated at 3 months. The percentages of eyes achieving 0.50 D or less of relative refractive cylinder in the non-laser-treated, toric, monofocal, and multifocal groups at 3 months were 71.6%, 74.5%, 62.5%, and 71.0%, respectively. The percentages of eyes in these four groups with MRSE accuracies deviating 0.50 D or less from the target at 3 months were 69.6%, 80.0%, 77.3%, and 82.0%, respectively. The image-guided surgical planning system was effective in accurate correction of preexisting astigmatism in eyes undergoing refractive cataract surgery with IOL implantation, as shown by residual refractive astigmatism and MRSE at 3 months. [J Refract Surg. 2018;34(12):824-831.].

Refractive outcomes of femtosecond laser–assisted secondary arcuate incisions in patients with residual refractive astigmatism after trifocal intraocular lens implantations

To evaluate the refractive and visual outcomes of arcuate incisions performed with the femtosecond laser in patients with a residual refractive astigmatism after refractive lens exchange (RLE) with trifocal intraocular lenses (IOLs). EuroEyes Clinical Group, Hamburg, Germany. Retrospective interventional case series. Pseudophakic patients with remaining refractive astigmatism after RLE with a trifocal IOL were treated with femtosecond laser-assisted corneal arcuate incisions. Patients who had a previous corneal treatment were excluded. Outcome measures were uncorrected (UDVA) and corrected distance visual acuities, manifest refraction, and a power vector analysis. The study enrolled 95 eyes of 70 patients. The mean follow-up was 5.6months±4.9 (SD). Constructing an astigmatic power vector (APV) with Jackson cross-cylinder axes at 180 degrees and 90 degrees and Jackson cross-cylinder axes at 45 degrees and 135 degrees, the mean preoperative vector length was 0.46±0.16 diopter (D). Themean postoperative APV was 0.17±0.16 D. This difference was statistically significant (P<.001). The difference between the UDVA preoperatively (0.17±0.15) and postoperatively (0.08±0.10) was statistically significant (P<.001). No intraoperative or postoperative complications were observed. Femtosecond laser-assisted corneal arcuate incisions were safe, efficient, and feasible to reduce refractive astigmatism after trifocal IOL implantation.

Effect of astigmatism on visual acuity after multifocal versus monofocal intraocular lens implantation

To determine whether there is a difference in how much residual astigmatism impacts uncorrected distance visual acuity (UDVA) after multifocal versus monofocal intraocular lens (IOL) implantation. Database study. Retrospective data review. An online toric IOL back-calculator allows users to input preoperative toric planning information and postoperative IOL orientation and refractive results. These data are used to determine the optimal orientation of the IOL to minimize residual refractive astigmatism. Aggregate data were extracted from this calculator to investigate factors associated withUDVA and relative magnitudes of residual astigmatic refractiveerror up to 2.5 diopters (D) after implantation of toric IOLs. Of 1919 pertinent records (455 multifocal toric IOLs and 1464 monofocal toric IOLs), a statistically significant difference by refractive cylinder category (P<.01) and a statistically significant difference by IOL type (P=.042) were noted.This difference was mostly driven by patients with residual refractive astigmatism of 1.5 D. The mean change in UDVA was 0.16 logarithm of the minimum angle of resolution per 1.0 D of astigmatism. Evaluating amore homogenous dataset withthe same monofocal and multifocal IOL design, therewas a statistically significant effect of refractive cylinder(P<.01) but nosignificant effect of IOL type (monofocal or multifocal, P=.45). The differences in UDVA at differentrefractive cylinder values was not statistically significantly different by orientation of the current astigmatism (P=.28). Residual astigmatism after toric IOL implantation impacts visual acuity similarly in patients who had multifocal and monofocal toric IOL implantation.

Factors Associated With Residual Astigmatism After Toric Intraocular Lens Implantation Reported in an Online Toric Intraocular Lens Back-calculator.

To evaluate factors associated with residual astigmatism after toric intraocular lens implantation based on data from an online toric intraocular lens (IOL) back-calculator. This was a retrospective data review of an online toric IOL back-calculator, which allows users to input preoperative toric planning information and postoperative lens orientation and refractive results. These data were used to determine the optimal orientation of the IOL to minimize residual refractive astigmatism. Aggregate data were extracted from this calculator to investigate factors associated with relative magnitudes of residual astigmatic refractive error after implantation of toric IOLs. A total of 3,159 validated records with an average reported postoperative refractive astigmatism of 1.85 diopters (D) were analyzed; 566 included data allowing calculation of surgically induced astigmatism. The relative magnitude of reported residual astigmatism appeared similar whether a femtosecond laser system was used or not. Significant differences relative to the use of intraoperative aberrometry were observed, as were differences by toric calculator. Higher measured surgically induced astigmatism was most associated with higher levels of reported residual astigmatism. A significant potential decrease in the mean refractive astigmatism was expected with IOL reorientation; in 1,416 cases (44.8%), the expected residual refractive astigmatism after lens reorientation was less than 0.50 D, with a mean reduction of 56% ± 31%. When present after cataract surgery, higher levels of residual refractive astigmatism were most associated with large differences in measured preoperative to postoperative keratometry. To a lesser degree, intraoperative aberrometry was associated with lower levels. [J Refract Surg. 2018;34(6):366-371.].

Low-power versus medium-power toric intraocular lenses in cataract surgery, about 110 eyes

To analyze the refractive predictability of low-power and medium-power toric intraocular lenses (IOL) during cataract surgery. A retrospective case series. Patients with low and moderate degrees of astigmatism were treated with either an Alcon AcrySof IQ toric monofocal lens (SN6AT2 or SN6AT3) or a Zeiss toric monofocal lens (709MP+1D or 709MP+1.5D). They were divided into two groups: group 1 with low-power toric IOL (n=40, SN6AT2 and 709MP+1), group 2 with medium-power toric IOL (n=70, SN6AT3 and 709MP+1.5D). Eyes were evaluated before and 1month after surgery. Uncorrected distance visual acuity (UDVA), corneal and total astigmatism were compared pre- and postoperatively. Vector astigmatism analysis was evaluated using the Alpins method. IOL alignment was checked postoperatively at slit lamp under pupil dilatation and on photos using Eyesuite® software (Luneau®). More than three-quarters of the patients in each group attained a visual acuity of at least 0.1LogMAR (0.8) without spectacles. The reduction of total astigmatism was significant in the two groups. The residual refractive astigmatism did not differ between the two groups (P=0.64) and was less than 0.4D. More than 80% of patients (82.5 vs 84.3%) presented a postoperative refractive spherical equivalent at ±0.50D (P=0.8). Vectorial astigmatism was significantly different in the two groups (0.43D in group 1, vs 0.27D in group 2; P=0.03). This is the first study comparing the low- versus medium-power toric IOLs, the most widely used. This study suggests very good refractive results both with low- and medium-power toric IOLs with a single surgical procedure.

New algorithm for toric intraocular lens power calculation considering the posterior corneal astigmatism

To assess the accuracy of toric intraocular lens (IOL) power calculations of a new algorithm that incorporates the effect of posterior corneal astigmatism (PCA). Abbott Medical Optics, Inc., Groningen, the Netherlands. Retrospective case report. In eyes implanted with toric IOLs, the exact vergence formula of the Tecnis toric calculator was used to predict refractive astigmatism from preoperative biometry, surgeon-estimated surgically induced astigmatism (SIA), and implanted IOL power, with and without including the new PCA algorithm. For each calculation method, the error in predicted refractive astigmatism was calculated as the vector difference between the prediction and the actual refraction. Calculations were also made using postoperative keratometry (K) values to eliminate the potential effect of incorrect SIA estimates. The study comprised 274 eyes. The PCA algorithm significantly reduced the centroid error in predicted refractive astigmatism (P<.001). With the PCA algorithm, the centroid error reduced from 0.50 @ 1 to 0.19 @ 3 when using preoperative K values and from 0.30 @ 0 to 0.02 @ 84 when using postoperative K values. Patients who had anterior corneal against-the-rule, with-the-rule, and oblique astigmatism had improvement with the PCA algorithm. In addition, the PCA algorithm reduced the median absolute error in all groups (P<.001). The use of the new PCA algorithm decreased the error in the prediction of residual refractive astigmatism in eyes implanted with toric IOLs. Therefore, the new PCA algorithm, in combination with an exact vergence IOL power calculation formula, led to an increased predictability of toric IOL power.

A novel nomogram for the treatment of astigmatism with femtosecond-laser arcuate incisions at the time of cataract surgery.

PurposeThe purpose of this study was to determine an arcuate incision (AI) nomogram to treat astigmatism during femtosecond laser-assisted cataract surgery.MethodsThis is a retrospective, cohort study. Femtosecond laser (FSL)-assisted transepithelial AIs were created at a 9.0 mm optical zone, 80% depth, centered on the limbus. We modified the manual Donnenfeld limbal relaxing incision nomogram to 70% for with-the-rule (WTR), 80% for oblique (OBL), and 100% for against-the-rule (ATR) astigmatism. The correction index (CI) equaled AI-induced astigmatism/target-induced astigmatism. Measures included preoperative keratometric corneal cylinder (Pre Kcyl), postoperative Kcyl (Post Kcyl), and postoperative residual refractive astigmatism (Post RRA).ResultsMean Pre Kcyl and 1–2 months Post RRA in 161 eyes of 116 patients were 0.626±0.417 diopters (D) (range 0.5–2 D), and 0.495±0.400 D (range 0–1.5 D), respectively. Mean absolute astigmatic changes (Pre Kcyl–Post Kcyl) without accounting for axis change in the WTR, ATR, and OBL groups were 0.165±0.383 D (P<0.001), 0.374±0.536 D (P<0.001), and 0.253±0.416 D (P=0.02), respectively. Mean absolute astigmatic changes using RRA as the postoperative measurement (Pre Kcyl–Post RRA) without accounting for axis change were 0.440±0.461 D (P<0.001), 0.238±0.571 D (P<0.05), 0.154±0.450 (P=0.111) in WTR, ATR, and OBL groups, respectively. CIs for WTR, ATR, and OBL were 0.53, 1.01, and 0.95, respectively. There were no intraoperative or postoperative complications related to the AIs.ConclusionTransepithelial FSL-AIs using the modified Donnenfeld nomogram show potential for management of mild to moderate corneal astigmatism. An increase in the magnitude or reduction of the optical zone size for the treatment of WTR and ATR astigmatism for this nomogram may further improve refractive accuracy.

Optimized keratometry and total corneal astigmatism for toric intraocular lens calculation

To compare keratometric astigmatism (KA) and different modalities of measuring total corneal astigmatism (TCA) for toric intraocular lens (IOL) calculation and optimize corneal measurementsto eliminate the residual refractive astigmatism. G.B. Bietti Foundation IRCCS, Rome, Italy. Prospective case series. Patients who had a toric IOL were enrolled. Preoperatively, a Scheimpflug camera (Pentacam HR) was used to measure TCA through ray tracing. Different combinations of measurements at a 3.0mm diameter, centered on the pupil or the corneal vertex and performed along a ring or within it, were compared. Keratometric astigmatism was measured using the same Scheimpflug camera and a corneal topographer (Keratron). Astigmatism was analyzed with Næser's polar value method. The optimized preoperative corneal astigmatism was back-calculated from the postoperative refractive astigmatism. The study comprised 62 patients (64 eyes). With both devices, KA produced an overcorrection of with-the-rule (WTR) astigmatism by 0.6 diopter (D) and an undercorrection of against-the-rule (ATR) astigmatism by 0.3 D. The lowest meridional error in refractive astigmatism was achieved by the TCA pupil/zone measurement in WTR eyes (0.27 D overcorrection) and the TCA apex/zone measurement in ATR eyes (0.07 D undercorrection). In the whole sample, no measurement allowed more than 43.75% of eyes to yield an absolute error in astigmatism magnitude lower than 0.5 D. Optimized astigmatism values increased the percentage of eyes with this error up to 57.81%, with no difference compared with the Barrett calculator and the Abulafia-Koch calculator. Compared with KA, TCA improved calculations for toric IOLs; however, optimization of corneal astigmatism measurements led to more accurate results.

Image-guided system versus manual marking for toric intraocular lens alignment in cataract surgery

To compare the accuracy of toric intraocular lens (IOL) alignment using the Verion Image-Guided System versus a conventional manual ink-marking procedure. University Eye Clinic Maastricht, Maastricht, the Netherlands. Prospective randomized clinical trial. Eyes with regular corneal astigmatism of at least 1.25 diopters (D) that required cataract surgery and toric IOL implantation (Acrysof SN6AT3-T9) were randomly assigned to the image-guided group or the manual-marking group. The primary outcome was the alignment of the toric IOL based on preoperative images and images taken immediately after surgery. Secondary outcome measures were residual astigmatism, uncorrected distance visual acuity (UDVA), and complications. The study enrolled 36 eyes (24 patients). The mean toric IOL misalignment was significantly less in the image-guided group than in the manual group 1hour (1.3 degrees±1.6 [SD] versus 2.8±1.8 degrees; P=.02) and 3months (1.7±1.5 degrees versus 3.1±2.1 degrees; P<.05) postoperatively. The mean residual refractive cylinder was -0.36±0.32 D and -0.47±0.28 D in the image-guided group and manual group, respectively (P>.05). The mean UDVA was 0.03±0.10logarithm of minimum angle of resolution (logMAR) and 0.04±0.09 logMAR, respectively (bothP>.05). No intraoperative complications occurred during any surgery. The IOL misalignment was significantly less with digital marking than with manual marking; this did not result in a better UDVA or lower residual refractive astigmatism.

The Effect of Lens Sphere and Cylinder Power on Residual Astigmatism and Its Resolution After Toric Intraocular Lens Implantation.

To analyze correlations between residual refractive cylinder (and its correction through lens reorientation) with the sphere and cylinder power of the toric intraocular lens (IOL) implanted. An online toric back-calculator (www.astigmatismfix.com) allows users to input toric IOL planning data, along with postoperative IOL orientation and refractive results; these data are used to determine the optimal orientation of the IOL to reduce refractive astigmatism. This was a retrospective data analysis; aggregate historical data were extracted from this calculator to investigate the relationship between residual refractive astigmatism and IOL cylinder and sphere power. A total of 12,812 records, 4,619 of which included IOL sphere power, were available for analysis. There was no significant effect of sphere power on residual refractive astigmatism (P = .25), but lower IOL cylinder powers were associated with significantly lower residual refractive astigmatism (P < .05). The difference between the intended and ideal orientation was higher in the lower IOL cylinder power groups (P < .01). Overcorrection of astigmatism was significantly more likely with higher IOL cylinder power (P < .01), but not with sphere power (P = .33). Reorientation to correct residual refractive cylinder to less than 0.50 diopters (D) was more successful with IOL cylinder powers of 1.50 D or less (P < .01); IOL sphere power had no apparent effect. There were significant effects of IOL cylinder power on residual refractive astigmatism, the difference between intended and ideal orientation, the likelihood of overcorrection, and the likelihood of astigmatism reduction with lens reorientation. IOL sphere power appeared to have no such effects. [J Refract Surg. 2017;33(3):157-162.].

Correction of irregular and induced regular corneal astigmatism with toric IOL after posterior segment surgery: a case series

BackgroundToric intraocular lens (IOL) implantation can be an effective method for correcting corneal astigmatism in patients with vitreoretinal diseases and cataract. Our purpose is to report the outcome of toric IOL implantation in two cases - a patient with scleral-buckle-induced regular corneal astigmatism and a patient with keratoconus following pars plana vitrectomy. As far as we are aware, there are no reported cases of toric IOL implantation in a vitrectomized eye with keratoconus nor of toric IOL implantation in patients with scleral-buckle-induced regular corneal astigmatism.Case presentationTwo patients with myopia and high corneal astigmatism underwent cataract operation with toric IOL implantation after posterior segment surgery. Myopia and high astigmatism (>2.5 diopter) were caused by previous scleral buckling in one case and by keratoconus in the other case. Pre- and postoperative examinations during the follow-up of included uncorrected and spectacle corrected distance visual acuity (UCDVA/CDVA), automated kerato-refractometry (Topcon), Pentacam HR, IOL Master (Zeiss) axial length measurements and fundus optical coherence tomography (Zeiss). One year postoperatively, the UCDVA and CDVA were 20/25 and 20/20 in both cases, respectively. The absolute residual refractive astigmatism was 1.0 and 0.75 Diopters, respectively. The IOL rotation was within 3° in both eyes, therefore IOL repositioning was not necessary. Complications were not observed in our cases.ConclusionThese cases demonstrate that toric IOL implantation is a predictable and safe method for the correction of high corneal astigmatism in complicated cases with different origins. Irregular corneal astigmatism in keratoconus or scleral-buckle-induced regular astigmatisms can be equally well corrected with the use of toric IOL during cataract surgery. Previous scleral buckling or pars plana vitrectomy seem to have no impact on the success of the toric IOL implantation, even in keratoconus. IOL rotational stability and refractive predictability in patients with a previous vitreoretinal surgery can be as good as in uncomplicated cases.

Pseudophakic astigmatism reduction with femtosecond laser-assisted corneal arcuate incisions: a pilot study.

PurposeThe aim of this study was to assess the effectiveness of the Verion-LenSx guided arcuate incision technique to reduce refractive astigmatism in a pseudophakic population.Patients and methodsA prospective single-arm study was conducted in which one or both eyes of subjects required reduction of 1.0–2.0 D of refractive astigmatism after previous cataract surgery or refractive lens exchange. The surgeon used the refractive cylinder in the eye and the Woodcock astigmatism nomogram for preoperative planning, while the LenSx femtosecond laser with the Verion Image Guided System was used to create all arcuate incisions. The primary outcome measure was the uncorrected monocular distance visual acuity (UCVA). Secondary outcome measures included the change in corneal astigmatism, the change in refractive astigmatism, the best-corrected visual acuity and spectacle independence at distance from preoperative stage to 1 month and 2 months postoperatively.ResultsTwenty-eight eyes of 18 subjects were treated. The best-corrected visual acuity at the 2-month postoperative (PO) stage was not statistically significantly different from the preoperative visual acuity (0.02 logarithm of the minimum angle of resolution [logMAR] in both cases, P>0.05). Uncorrected visual acuity was statistically significantly better at the 2-month PO stage relative to the preoperative value (0.14 versus 0.34 logMAR, P<0.01). The mean change in refractive cylinder from the preoperative stage to the 2-month PO stage was 1.0 D. At the 2-month PO stage, two-thirds of the subjects (12/18) reported that they did not use glasses for distance vision and that their spectacle use for distance vision at 2 months was “lower” or “much lower” than the preoperative stage; in 71% of eyes (20/28), the residual refractive cylinder was ≤0.50 D. Vector changes in keratometric astigmatism were weakly associated with changes in refractive cylinder.ConclusionArcuate incisions made with a femtosecond laser to treat moderate levels of residual refractive astigmatism after previous cataract surgery may reduce dependence on spectacles for distance vision.

Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK.

PurposeTo evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies.SettingPrivate clinical ophthalmology practice.Patients and methodsA total of 100 eyes (50 patients) in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform (FS200 femtosecond and EX500 excimer lasers) were randomized for treatment as follows: one eye with the standard clinical refraction (group A) and the contralateral eye with the topographic astigmatic power and axis (topography-modified treatment refraction; group B). All cases were evaluated pre- and post-operatively for the following parameters: refractive error, best corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), topography (Placido-disk based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months.ResultsMean refractive error was −5.5 D of myopia and −1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/200 to 20/20 versus 20/16; post-operative CDVA was 20/20 and 20/13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over −0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B (P<0.01). The residual percentages in both groups were measured with refractive astigmatism of more than −0.5 diopters.ConclusionTopography-modified refraction (TMR): topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings may change the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction.

Toric intraocular lens orientation and residual refractive astigmatism: an analysis.

PurposeTo analyze intraocular lens (IOL) orientation data from an online toric back-calculator (astigmatismfix.com) for determining if differences were apparent by lens type.MethodsA retrospective review of astigmatismfix.com toric back-calculations that included IOL identification and intended orientation axis.ResultsOf 12,812 total validated calculation records, 8,229 included intended orientation and lens identification data. Of the latter, 5,674 calculations (69%) involved lenses oriented 5° or more from their intended position. Using estimated toric lens usage data, the percentage of lenses with orientation ≥5° from intended was 0.89% overall, but the percentage varied significantly between specific toric lens brands (P<0.05). The percentage of back-calculations related to lenses that were not oriented as intended was also statistically significantly different by lens brand (P<0.05). When IOLs were misoriented, they were significantly more likely to be misoriented in a counterclockwise direction (P<0.05). This was found to be due to a bias toward counterclockwise orientation observed with one specific brand, a bias that was not observed with the other three brands analyzed here.ConclusionThe percentage of eyes with lens orientation ≥5° from intended in the Toric Results Analyzer data set was <1% of toric IOLs in general, with the relative percentage of Tecnis® Toric IOLs significantly higher than AcrySof® Toric IOLs. Both of these had higher rates than the Staar® Toric and Trulign® Toric lenses, with the availability of higher Tecnis and AcrySof cylinder powers a likely contributing factor. The AcrySof Toric IOL appears to be less likely than the Tecnis Toric IOL to cause residual astigmatism as a result of misorientation. The Tecnis Toric IOL appears more likely to be misoriented in a counterclockwise direction; no such bias was observed with the AcrySof Toric, the Trulign® Toric, or the Staar Toric IOLs.

Threshold limit of postoperative astigmatism for patient satisfaction after refractive lens exchange and multifocal intraocular lens implantation

To determine the degree of tolerance toward different magnitudes of residual refractive astigmatism and corneal astigmatism and the angles of corneal astigmatism after implantation of an asymmetric multifocal intraocular lens (IOL). Cathedral Eye Clinic, Belfast, United Kingdom. Retrospective comparative case series. The study enrolled patients having refractive lens exchange and implantation of a Lentis Mplus LS-312 MF30 IOL. Uncorrected (UDVA) and corrected distance visual acuities, uncorrected near and intermediate visual acuities, and quality-of-vision questionnaires were evaluated. Groups were categorized based on the magnitude of refractive astigmatism and corneal residual astigmatism. Refractive astigmatism of less than 0.50 diopter (D) and more than 0.50 D and corneal astigmatism of 0.50 D or less, 0.51 to 0.75 D, 0.76 to 1.00 D, and more than 1.00 D were categorized. The study comprised 117 patients (234 eyes). There was a significant difference in UDVA (P=.003), refractive sphere (P=.001), and defocus equivalent (P≤.001) between the residual refractive astigmatism groups; however, there was no difference in quality of vision (P=.28). The same was found for corneal astigmatism with UDVA (P≤.001) and quality of vision (P=.16). The angle of corneal astigmatism in relation to IOL placement did not statistically affect postoperative outcomes. The IOL appeared to subjectively tolerate residual astigmatism well despite a statistically significant difference in UDVA with higher magnitudes of residual astigmatism. The angle of residual corneal astigmatism in relation to IOL placement did not have a significant effect on postoperative outcomes. None of the authors has a financial or proprietary interest in any material or method mentioned.

Retreatments after multifocal intraocular lens implantation: an analysis.

PurposeTo determine the incidence and etiology of required retreatment after multifocal intraocular lens (IOL) implantation and to evaluate the methods and clinical outcomes of retreatment.Patients and methodsA retrospective chart review of 416 eyes of 209 patients from one site that underwent uncomplicated cataract surgery with multifocal IOL implantation. Biometry, the IOL, and refractive data were recorded after the original implantation, with the same data recorded after retreatment. Comments related to vision were obtained both before and after retreatment for retreated patients.ResultsThe multifocal retreatment rate was 10.8% (45/416 eyes). The eyes that required retreatment had significantly higher residual refractive astigmatism compared with those who did not require retreatment (1.21±0.51 D vs 0.51±0.39 D, P<0.01). The retreatment rate for the two most commonly implanted primary IOLs, blended bifocal (10.5%, 16/152) and bilateral trifocal (6.9%, 14/202) IOLs, was not statistically significantly different (P=0.12). In those requiring retreatment, refractive-related complaints were most common. Retreatment with refractive corneal surgery, in 11% of the eyes, and piggyback IOLs, in 89% of the eyes, was similarly successful, improving patient complaints 78% of the time.ConclusionComplaints related to ametropia were the main reasons for retreatment. Residual astigmatism appears to be an important determinant of retreatment rate after multifocal IOL implantation. Retreatment can improve symptoms for a high percentage of patients; a piggyback IOL is a viable retreatment option.

Correction of low corneal astigmatism in cataract surgery.

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. 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. 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. 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.

Management of moderate and severe corneal astigmatism with AcrySof® toric intraocular lens implantation – Our experience

PurposeVisual performance following toric intraocular lens implantation for cataract with moderate and severe astigmatism. SettingCataract services, Shroff Eye Centre, New Delhi, India. DesignCase series. MethodThis prospective study included 64 eyes of 40 patients with more than 1.50 dioptre (D) of pre-existing corneal astigmatism undergoing phacoemulsification with implantation of the AcrySof® toric IntraOcular Lens (IOL). The unaided visual acuity (UCVA), best corrected visual acuity (BCVA), residual refractive sphere and refractive cylinders were evaluated. Toric IOL axis and alignment error was measured by slit lamp method and Adobe Photoshop (version 7) method. Patient satisfaction was evaluated using a satisfaction questionnaire at 3months. ResultsThe mean residual refractive astigmatism was 0.57 D at the final follow-up of 3months. Mean alignment error was 3.44 degrees (SD=2.60) by slit lamp method and 3.88 degrees (SD=2.86) by Photoshop method. Forty-six (71.9%) eyes showed misalignment of 5 degrees or less, and 60 (93.8%) eyes showed misalignment of 10 degrees or less. The mean log MAR UCVA at 1st post-op day was 0.172 (SD=0.02), on 7th post-op day was 0.138 (SD=0.11), and on 30th post-op day was 0.081 (SD=0.11). The mean log MAR BCVA at three months was −0.04 (SD=0.76). ConclusionWe believe that implantation of AcrySof® toric IOL is an effective, safe and predictable method to correct high amounts of corneal astigmatism during cataract surgery.