Outcome of Toric Intraocular Lens Implantation After Adjusting for Anterior Chamber Depth and Intraocular Lens Sphere Equivalent Power Effects

Relation between change of effective lens position and toric IOL rotation after toric IOL implantation

OBJECTIVE

To evaluate the relationship between change of effective lens position (ELP) and toric intraocular lens (IOL) rotation in patients with increasing postoperative refractive astigmatism after successful toric IOL implantation.

METHODS

The subjects include 61 people (61 eyes) with increasing residual astigmatism >0.5 D 3 months after successful toric IOL implantation. Clinical measurements included preoperative, 1-week, and 1-, 2-, and 3-month postoperative visual acuity; refraction; keratometer; anterior and posterior corneal astigmatism; ELP by Scheimpflug camera imaging; and IOL axis by slit-lamp biomicroscopic photograph with pupil dilation.

RESULTS

Residual astigmatism in postoperative month 3 (0.81 ± 0.50 D) is higher than that at postoperative week 1 (0.41 ± 0.38 D; p < 0.05). ELP decreased by 264.44 ± 163.25 μm, and the IOL rotated by 2.91 ± 1.44 degrees from week 1 to month 3 (p < 0.05). The ELP change had a positive correlation with IOL rotation (R2 = 0.383; p = 0.006), and the postoperative refractive astigmatic change had a positive correlation with ELP change (R2 = 0.272; p = 0.027) and IOL rotation (R2 = 0.272; p = 0.0001) from week 1 to month 3.

CONCLUSION

ELP change can influence toric IOL rotation and increase residual astigmatism after toric IOL implantation.

Evaluation of statistical correction strategies for corneal back surface astigmatism with toric lenses: a vector analysis

PURPOSE

To compare actual and formula-predicted postoperative refractive astigmatism using measured posterior corneal power measurements and 4 different empiric posterior corneal astigmatism correction models.

SETTING

Tertiary care center.

DESIGN

Single-center retrospective consecutive case series.

METHODS

Using a dataset of 211 eyes before and after tIOL implantation (Hoya Vivinex), IOLMaster 700 (IOLM) or Casia2 (CASIA) keratometric and front/back surface corneal power measurements were converted to power vector components C0 (0/90 degrees) and C45 (45/135 degrees). Differences between postoperative and Castrop formula predicted refraction at the corneal plane using the labeled parameters of the tIOL and the keratometric or front/back surface corneal powers were recorded as the effect of corneal back surface astigmatism (BSA).

RESULTS

Generally, the centroid of the difference shifted toward negative C0 values indicating that BSA adds some against the rule corneal astigmatism (ATR). From IOLM/CASIA keratometry, the average difference in C0 was 0.39/0.32 diopter (D). After correction with the Abulafia-Koch, Goggin, La Hood, and Castrop nomograms, it was -0.18/-0.24 D, 0.27/0.18 D, 0.13/0.08 D, and 0.17/0.10 D. Using corneal front/back surface data from IOLM/CASIA, the difference was 0.18/0.12 D.

CONCLUSIONS

The Abulafia-Koch method overcorrected the ATR, while the Goggin, La Hood, and Castrop models slightly undercorrected ATR, and using measurements from the CASIA tomographer seemed to produce slightly less prediction error than IOLM.

Comparison of clinical outcomes of Eyecryl toric and Alcon toric intra-ocular lenses - A real world study

Purpose

To compare the visual outcomes and residual astigmatism following implantation of Eyecryl toric versus Alcon AcrySof IQ toric intra-ocular lenses (IOLs).

Methods

This retrospective, observational study included 143 eyes of 141 patients who underwent phaco-emulsification, followed by implantation of Eyecryl toric IOL (n = 83 eyes) or Alcon toric IOL (n = 60 eyes) in an eye hospital in South India from 2018 to 2021. At 1 month post-op, the uncorrected distance visual acuity (UCVA), best corrected distance visual acuity (BCVA), and residual astigmatism of the toric IOL were compared and analyzed.

Results

The mean pre-op corneal astigmatism was 2.02 ± 0.81 D and 1.70 ± 0.68 D in the Alcon and Eyecryl groups, respectively (P = 0.005). The mean post-op corneal astigmatism at 1 month was 0.50 ± 0.51 D and 0.36 ± 0.42 D in the Alcon and Eyecryl groups, respectively, with no statistically significant difference between them (P = 0.87). The mean post-op UCVA in logarithm of minimum angle of resolution (logMAR) at 1 month was similar between the groups at 0.17 ± 0.18 and 0.17 ± 0.16 in the Alcon and Eyecryl groups, respectively (P = 0.98). The mean post-op BCVA in logMAR at 1 month was 0.06 ± 0.09 and 0.03 ± 0.10 in the Alcon and Eyecryl groups, respectively (P = 0.02).

Conclusion

Both Eyecryl toric and Alcon AcrySof IQ toric IOLs showed comparable post-operative outcomes in terms of UCVA and residual astigmatism. The post-op BCVA was clinically similar between groups but statistically better in the Eyecryl toric group.

Intraocular lens constant optimization in toric intraocular lens calculation using keratometry and total corneal power

PURPOSE

To evaluate intraocular lens (IOL) constant optimization in toric IOL calculation with keratometry (K) and total corneal refractive power (TCRP).

METHODS

Predicted spherical equivalent (SE) and residual astigmatism (RA) with K and TCRP were retrospectively calculated using the Haigis, Holladay 1, and SRK/T formulae and optimized IOL constants. The results of the Barrett calculator and the Abulafia-Koch formula with K were also calculated. The median absolute error in SE (MedAE-SE), mean absolute error in RA (MAE-RA), and centroid error (CE) were analyzed.

RESULTS

Seventy-nine eyes of 71 patients implanted with toric IOLs were included. With K, there were no significant differences between the results before and after constant optimization using all the formulae. With TCRP, constant optimization significantly reduced MedAE-SE; however, significantly increased MAE-RA and CE using the Holladay 1 and SRK/T formulae. MedAE-SE, MAE-RA, and CE using the Haigis formula did not show significant differences. The difference in the predicted RA before and after constant optimization increased with IOL toricity. The MedAE-SE predicted by TCRP was significantly higher than that predicted by K despite constant optimization. The MAE-RA and CE predicted by TCRP were significantly lower than those predicted by K without posterior corneal astigmatism optimization; however, were not significantly different from those predicted by the Barrett and Abulafia-Koch formulae.

CONCLUSIONS

Constant optimization is recommended when using the TCRP in toric IOL calculations, particularly for patients with large astigmatism. However, TCRP did not yield more accurate results than optimized K in toric IOL calculations despite constant optimization.

Toric intraocular lenses: Evidence‐based use

Uncorrected refractive astigmatism degrades visual acuity. Spherical intraocular lenses (IOLs) leave astigmatic errors resident in the cornea manifest in refractive astigmatism. Toric IOLs, correcting for this corneal astigmatism, contribute to spectacle‐free vision in the pseudophakic eye. This review provides information to assist surgeons in a rational choice of eyes suitable for toric IOL implantation, methods of IOL cylinder power calculation, surgical techniques for toric IOLs and management of complications. With appropriate application of this information, correction of visually detrimental astigmatism can be achieved routinely.

Comparison of surgically induced astigmatism between anterior and total cornea in 2.2 mm steep meridian incision cataract surgery

Background

This study aimed to compare surgically induced astigmatism (SIA) on the anterior and total cornea during cataract surgery through a 2.2 mm steep meridian incision.

Methods

The study included 69 left eyes of 69 patients who had undergone cataract surgery. The 69 eyes were classified into three subgroups according to the preoperative steep meridian. Following phacoemulsification, an intraocular lens was inserted into the bag. The keratometric measurements were taken 12 months postoperatively, on the anterior cornea (automated keratometer and anterior keratometry [K] from a rotating Scheimpflug camera) and total cornea (equivalent K reading [EKR] 3.0 mm, EKR 4.5 mm, total corneal refractive power (TCRP) 2.0 mm ring, TCRP 3.0 mm zone, TCRP 4.0 mm zone). The SIA was analyzed for each parameter.

Results

On the double-angle polar plot, the summated vector mean values of SIA determined by the automated keratometer and Scheimpflug anterior K were 0.28 diopter (axis: 177°) and 0.37 diopter (axis: 175°) in with-the-rule (WTR) astigmatism; 0.03 diopter (axis: 156°) and 0.18 diopter (axis: 177°) in oblique astigmatism; 0.15 diopter (axis: 96°) and 0.17 diopter (axis: 73°) in against-the-rule (ATR) astigmatism. The mean SIAs on the total cornea ranged from 0.31 to 0.42 diopter in WTR astigmatism; from 0.16 to 0.27 diopter in oblique astigmatism; from 0.04 to 0.11 diopter in ATR astigmatism. Mean magnitude SIA ranged from 0.41 to 0.46 diopter on anterior corneal surface and 0.50 to 0.62 diopter on total cornea. J₀ and J₄₅ of the posterior cornea showed no significant changes after cataract surgery, and the changes in J₀ and J₄₅ did not show any statistical differences between the anterior and total cornea (all p > 0.05).

Conclusions

There were no differences in the summed vector mean values of SIA between the anterior cornea and the total cornea.

The Relationship Between the Change of Intraocular Lens Position and Capsular Bend After Cataract Surgery

PURPOSE

To explore the relationship between the change in intraocular lens (IOL) position and capsular bend after cataract surgery.

METHODS

Patients underwent phacoemulsification and IOL implantation (Alcon Laboratories, Inc). Patients were divided into two groups based on preoperative axial length: long axial length group (axial length ⩾ 26 mm) and normal axial length group (axial length > 22 but < 26 mm). Swept-source optical coherence tomography was performed at 1 day, 1 week, 1 month, and 3 months after mydriasis to obtain postoperative aqueous depth (PAD) and capsular bend index (CBI). The relationship between CBI and PAD changes was analyzed.

RESULTS

Eighty patients (80 eyes) were included in the study. PAD decreased gradually from 1 day to 1 week and increased from 1 week to 3 months. Mean CBI was moderately positively correlated with PAD changes (r = 0.586, P < .001). The IOL moved forward gradually when the CBI was less than 2.30 and the IOL gradually moved backward when the CBI was 2.30 or greater. The root mean square of the change in PAD was smaller in the long axial length group (0.08 ± 0.04 mm) than in the normal axial length group (0.09 ± 0.05 mm) during the 3 months after surgery (P = .036).

CONCLUSIONS

The position of the IOL was almost stable 1 month after operation, and postoperative capsule adhesion mainly occurred within 1 month. The change in PAD was related to capsule adhesion. The postoperative position of the IOL was relatively stable and capsular bend was relatively slow for the long axial length group over 3 months. [J Refract Surg. 2021;37(5):324-330.].

Comparison of the clinical efficacy of AcrySof® IQ and TECNIS® toric intraocular lenses: A real-world study

Corneal astigmatism significantly compromises uncorrected visual acuity (UCVA) after phacoemulsification with implantation of traditional spherical or non-spherical monofocal intraocular lens (IOL). Toric IOL provides an effective way to gain favorable postoperative UCVA for the patients with cataracts with corneal astigmatism. There are numerous types of toric IOLs; however AcrySof^® IQ toric IOL (Alcon Laboratories, Inc.) and TECNIS^® toric IOL (Johnson & Johnson Vision; Johnson & Johnson) are most frequently used in our clinical practice. The purpose of the current study was to compare the clinical efficacy of AcrySof IQ with TECNIS toric IOL implantation, and to provide a clinical basis on selecting an appropriate toric IOL before cataract surgery for patients with corneal astigmatism. A total of 30 patients with cataract (44 eyes) with corneal astigmatism [0.82-7.27 diopters (D)], who have undergone phacoemulsification with toric IOL implantation between October 2012 and December 2017, were included in the current retrospective cohort study. Patients were divided into two groups: One group (26 eyes) received the AcrySof IQ toric IOL (AcrySof group) and the other group (18 eyes) received the TECNIS toric IOL (Tecnis group). The indexes of curative effect, such as uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively), refractive outcomes, contrast sensitivity (CS), IOL rotation, and satisfaction, were evaluated. Both toric IOLs significantly improved UDVA and CDVA. Postoperative mean residual astigmatism was similar in the AcrySof group and in the Tecnis group (0.75±0.50 and 0.78±0.90 D; P=0.896). There was no statistically significant between postoperative CS in the AcrySof and Tecnis groups. Rotations of >10˚ were considered to be significant and were identified in three eyes. The mean IOL rotation showed no statistically significant difference (AcrySof group, 0.24±5.54˚; Tecnis group, -0.19±6.28˚; P=0.416). The mean patient satisfaction score was 8.46±1.21 in the AcrySof group and 8.78±1.44 in the Tecnis group (P=0.260). The results of the current study indicated that patients with cataracts with corneal astigmatism undergoing phacoemulsification with AcrySof IQ and TECNIS toric IOL implantation achieved similar clinical efficacy in term of visual outcomes, refraction correction, CS, rotational stability and satisfaction.

How Can We Improve Toric Intraocular Lens Calculation Methods? Current Insights

In this paper, we review current strategies for calculating toric intraocular lenses (IOLs). We discuss the prevalence and clinical relevance of astigmatism and the assessment of toric IOL candidates. We detail recommendations for evaluating astigmatism and current biometry and IOL power calculation techniques. Finally, error sources and results of current toric IOL calculators are discussed.

Clinical Outcomes of Toric Intraocular Lenses: Differences in Expected Outcomes When Using a Calculator That Considers Effective Lens Position and the Posterior Cornea vs One That Does Not

Purpose

To compare toric intraocular lens (IOL) outcome accuracy after using an online toric calculator that accounted for posterior corneal astigmatism versus a traditional calculator that only accounted for anterior corneal astigmatism.

Patients and Methods

This was a single-arm, non-masked, non-randomized prospective study in a single private practice in Norfolk, Virginia, USA, evaluating clinical outcomes of toric IOL implantation based on a calculator that considered posterior corneal astigmatism (PCA) and effective lens position (ELP). Of interest was the distribution of the residual refraction (sphere and cylinder) at 40–70 days postoperative. Residual refractive cylinder (RRC) was compared to the back-calculated theoretical results using a legacy calculator that did not consider PCA. Distance visual acuity (best-corrected and uncorrected) and the manifest refraction were also measured, along with preoperative and postoperative keratometry.

Results

Forty-six eyes of 34 subjects were available for analysis. All eyes had a spherical equivalent refraction within 0.5D of intended. Uncorrected visual acuity was 20/25 or better in 86% of eyes targeted for emmetropia. Residual cylinder was 0.50D or less in 96% of eyes, with a maximum of 0.75D measured. The difference between residual cylinder and the expected cylinder from calculations was significantly lower for the calculator that included consideration of PCA and ELP relative to the one that did not.

Conclusion

Use of a toric IOL calculator that includes consideration of posterior corneal astigmatism is recommended to optimize clinical outcomes.

The Effect of Corneal Higher Order Aberrations on Postoperative Residual Astigmatism after Toric IOL Implantation

Background: To demonstrate the effect of preoperative higher order aberrations (HOAs) on postoperative residual astigmatism in toric intraocular lens (IOL) implantation. Methods: A retrospective, controlled, comparative study that involved patients who underwent toric IOL implantation. Patients were divided into two groups according to the difference between the estimated residual astigmatism and actual postoperative astigmatism [difference ≤0.5 diopters (D), Group A; difference >0.5 D, Group B]. Corneal astigmatisms with axis, and various aberration values were compared between the two groups. Results: Total RMS and HOA RMS values in Group B were significantly higher than those in Group A (p < .001, = 0.003). The vertical coma value, and its absolute value, in Group B were significantly higher than those in Group A (p < .001, = 0.002). The total RMS and absolute value of the vertical coma showed a positive linear correlation with the degree of residual postoperative astigmatism (R-square = 0.139, 0.131; p = .027, 0.036). Conclusions: If the residual astigmatism after insertion of the toric IOL was greater than expected, corneal aberrations, shown by total RMS and HOA RMS values before surgery, especially of the vertical coma, tended to be high.

Intrasubject Repeatability and Interdevice Agreement of Anterior Chamber Depth Measurements by Orbscan and Pentacam in Different Grades of Keratoconus

OBJECTIVES

To evaluate the repeatability of anterior chamber depth (ACD) measurements by Orbscan and Pentacam imaging devices in different grades of keratoconus.

METHODS

One examiner performed 3 consecutive ACD measurements with both devices on 74 eyes of 42 keratoconus patient. Repeatability was assessed using intrasession test-retest variability. Within-subject SD was determined for repeatability, and the coefficient of variation was calculated for each measurement. The intraclass correlation coefficient (ICC) was also determined to assess the variance of repeated data.

RESULTS

Overall, the three ACD measurements were not significantly different either with Pentacam or Orbscan. The ICC index values were greater than 90% with both devices, and it significantly reduced at higher grades of keratoconus with Pentacam. Interdevice differences were statistically significant. The interdevice agreement with ACD measurements was 0.981, and the agreement was lower at higher grades of keratoconus. The 95% limits of agreement between the 2 devices for ACD was from -0.19 to 0.04.

CONCLUSIONS

Our results indicate acceptable repeatability for ACD measurements with both Orbscan and Pentacam in keratoconus patients. The progression of keratoconus has no significant effect on repeatability results of these devices. The good agreement between them allows their interchangeable use.

Vector analysis investigation of toric intraocular lens with no deviation from the intended axis

AIM

The aim of this research was to evaluate vector analysis after implantation of toric intraocular lenses (IOLs) without deviation from the intended axis.

METHODS

The study included 18 eyes of 16 patients who underwent cataract surgery with the insertion of a toric implant (AcrySof IQ Toric). The postoperative IOL meridian placement completely corresponded to that planned. Using vector analysis, surgically induced astigmatism (SIA) was derived from the refractive outcome versus the predicted postoperative keratometric astigmatism and was compared with targeted induced astigmatism (TIA). The difference vector (DV) was derived by calculating the vector expression of the remaining astigmatic change.

RESULTS

The mean postoperative remaining refractive astigmatism of 0.73±0.55 diopters (D) was achieved versus the mean target of 0.44±0.28 D. There was a difference of 0.29 D between the target and achieved values. The mean SIA value was 1.90±0.99 D compared with the mean TIA value of 2.00±0.85 D. The mean DV value was 0.87±0.56 D. The astigmatism correction index (SIA/TIA) was 0.95, which was near the ideal value of 1. The index of success (DV/TIA) was 0.44, which was far from the ideal value of 0.

CONCLUSION

The implantation of toric IOLs is an effective, predictable method for astigmatic correction. However, some remaining astigmatism is present even if toric IOLs are placed accurately.

Evaluation of Toric Intraocular Lenses in Patients With Low Degrees of Astigmatism

PURPOSE

This study aimed to describe the efficacy of toric intraocular lenses (IOLs) in patients with low degrees of corneal astigmatism.

DESIGN

Retrospective case series was undertaken.

METHODS

Patients with low amounts of corneal astigmatism who were treated with either a toric monofocal lens (SN6AT2 Toric, n = 76) or a toric multifocal lens (SND1T2 +3.00, n = 44) were reviewed. Eyes were evaluated preoperatively and 3 months postoperatively. Refraction and visual outcomes were monitored.

RESULTS

Patients (69.7%) in the monofocal toric group obtained refractive cylinder less than 0.25 diopters (D) compared with 70.5% of the multifocal toric group. Both toric groups showed a statistically significant reduction in refractive cylinder after surgery (P = 0.001). Monofocal (66.7%) and multifocal (68.2%) toric patients achieved uncorrected distance visual acuity of 20/20 or better.

CONCLUSIONS

This represents the first article to investigate the use of low-power toric IOLs in patients with less than 1.25 D of corneal cylinder. Before the development of low-power toric IOLs, patients with low to moderate amounts of astigmatism required concurrent intraoperative adjustments or additional forms of treatment to benefit from cataract and IOL surgery. Evidence suggests that the toric T2 IOL now removes this barrier, providing consistent, accurate refractive and astigmatic results, and enables these patients to achieve excellent outcomes with a single treatment across IOL platforms. Larger studies will help to consolidate our results.

Comparison of the Astigmatic Power of Toric Intraocular Lenses Using Three Toric Calculators

PURPOSE

To compare the astigmatic power of toric intraocular lenses (IOLs) obtained from the AcrySof, TECNIS, and iTrace toric calculator in patients with preoperative with-the-rule (WTR) or against-the-rule (ATR) corneal astigmatism.

MATERIALS AND METHODS

Fifty eyes with cataract and corneal astigmatism greater than 0.75 diopters were enrolled in each group (WTR and ATR). Keratometric values were measured using autokeratometry, an IOLMaster, and an iTrace, which incorporated corneal topography and ray-tracing aberrometry. Based on measured keratometric values, the astigmatic power of each toric IOL was calculated using three toric calculators.

RESULTS

Bland-Altman plots showed good agreement between six pairwise corneal astigmatism values in both groups. The TECNIS calculator tended to suggest a higher astigmatic power of the toric IOL than the AcrySof calculator. With the higher astigmatism and keratometric values from the IOLMaster, in both groups, calculations from the AcrySof and TECNIS calculators resulted in higher calculated astigmatic powers than those from same calculators with autokeratometry-measured values, demonstrating good agreement. With the higher calculated astigmatic power values, the values from the iTrace toric calculator using keratometric values obtained from iTrace ray tracing wavefront aberrometry or iTrace simulated keratometry showed fair to moderate agreement with those from the other calculator-keratometry pairs in both groups.

CONCLUSION

To achieve the best refractive outcome after toric IOL implantation, understanding the differences in keratometric values between instruments and in calculated astigmatic power among toric calculator programs is necessary. Moreover, systemic analysis of each toric calculator in conjunction with postoperative data is required.

Adjustment of anterior corneal astigmatism values to incorporate the likely effect of posterior corneal curvature for toric intraocular lens calculation

PURPOSE

To establish if average refractive overcorrection or undercorrection of corneal astigmatism based on the "rule" of the astigmatism occurs if toric intraocular lenses (IOLs) are calculated on the basis of anterior corneal measurements, and to calculate an adjustment for individual eyes to avoid this systematic error.

METHODS

One hundred forty-three consecutive eyes of 115 patients underwent phacoemulsification with IOL powers calculated using anterior corneal curvature data alone. Eyes were grouped as either "with-the-rule" or "against-the-rule" on the basis of the steep anterior corneal meridian. Targeted versus achieved astigmatic outcomes were compared. Main outcome measure was residual refractive astigmatism following the insertion of a toric IOL due to the likely effect of posterior corneal astigmatism.

RESULTS

Significant prediction errors in astigmatic outcome occurred only with IOL cylinders of 2 diopters or less. Overcorrection occurred by a factor of 1.38 in with-the-rule eyes and undercorrection occurred by a factor of 0.65 in against-the-rule eyes.

CONCLUSIONS

A coefficient of adjustment of 0.75 for with-the-rule eyes and 1.41 for against-the-rule eyes can be applied to the corneal astigmatism power value to calculate a more appropriate IOL cylinder power than that calculated by using unadjusted anterior corneal curvature measurements. These adjustment coefficients apply only to those eyes that would have received IOLs with 2 diopters of cylinder or less and calculated with such unadjusted measurements. Greater IOL cylinder powers are sufficiently accurately calculated using unadjusted values.

Rotational stability of a single-piece toric acrylic intraocular lens: a pilot study

PURPOSE

To evaluate the visual performance and rotational stability of the Tecnis Toric 1-piece intraocular lens (IOL) during the first 3 postoperative months.

DESIGN

Prospective, single-center study.

METHODS

In this study, patients with age-related cataract and corneal astigmatism of 1.0 to 3.0 diopters measured with the IOLMaster 500 (Carl Zeiss Meditec AG) were included. Before surgery, rotating Scheimpflug scans (Pentacam HR; Oculus) were performed and the cornea was marked in the sitting position at the slit lamp. Patients received a single-piece toric hydrophobic acrylic IOL (Tecnis Toric; AMO). Immediately and 3 months after surgery, retroillumination photographs were obtained to assess the rotational stability of the IOL. Additionally, Autorefraction (Topcon), subjective refraction, uncorrected and distance-corrected visual acuity, keratometry, and Scheimpflug and ocular wavefront (WASCA, Carl Zeiss Meditec AG) measurements were performed at the 3-month follow-up.

RESULTS

Thirty eyes of 30 patients were included in this study. Mean absolute difference between the IOL axis at the 3-month and 1-hour follow-up was 2.7 degrees (standard deviation, 3.0 degrees). The IOL rotation was less than 3 degrees and less than 6 degrees in 62% and 95% of all cases, respectively.

CONCLUSIONS

The Tecnis Toric 1-piece IOL is rotationally stable and shows excellent capsule bag performance and refractive outcomes.

Comparison of Toric Intraocular Lenses and Arcuate Corneal Relaxing Incisions to Correct Moderate to High Astigmatism in Cataract Surgery

PURPOSE

To compare toric intraocular lens (IOL) implantation with arcuate corneal relaxing incisions for moderate to high corneal astigmatism during cataract surgery.

DESIGN

A retrospective comparison study.

METHODS

This 12-month single-surgeon study compared eyes with cataract and preexisting astigmatism of 1.75 diopters (D) or greater (range, 1.75-5.25 D) receiving corneal arcuate relaxing incisions or toric IOL implantation. Main outcome measures were visual acuity, refractive results, and IOL axis determination.

RESULTS

There were 45 and 20 eyes in the toric IOL and arcuate incision groups, respectively. Preoperative data were not significantly different between the 2 groups; the mean preoperative astigmatism was 2.16 ± 0.93 D in the toric IOL group and 2.41 ± 0.76 D in the incisional group. At 6 months postoperatively, the mean residual astigmatism was 0.75 and 1.33 D (P = 0.000), respectively; 82.2% and 44.4% of eyes were 1.00 D or less (P = 0.000), and 35.7% and 16.7% of eyes were 0.50 D or less (P = 0.000), respectively. Uncorrected distance visual acuity improved in both groups; eyes in the toric IOL group were more likely to be 20/30 or better (87% vs 29%, P = 0.008). Following surgery, all eyes had best corrected visual acuity of 20/40 or greater, and no eye lost a line of vision. The mean toric IOL rotation was 2.6 ± 1.7 degrees (range, 0-6 degrees).

CONCLUSIONS

Both toric IOLs and arcuate corneal incisions reduce moderate to high preexisting corneal astigmatism during cataract surgery; however, toric IOL implantation was more effective and predictable.

Comparison of surgically induced astigmatism between one-handed and two-handed cataract surgery techniques

Background

The purpose of this study was to compare surgically induced astigmatism (SIA) between one-handed and two-handed cataract surgery techniques.

Methods

Eighty-eight eyes of 44 patients with no ocular disease other than cataract, who underwent cataract surgery by a single surgeon, were selected for this study. Cataract surgery was performed by coaxial phacoemulsification and intraocular lens implantation via a 2.4 mm transconjunctival single-plane sclerocorneal incision at the 12 o’clock position. In each patient, one eye was subjected to coaxial phacoemulsification using a one-handed technique while the fellow eye was subjected to coaxial phacoemulsification using a two-handed technique. For the two-handed technique, a corneal side port was created at the 2 o’clock position. The appropriate incision meridian was identified by a preoperative axis mark. SIA was calculated using the Alpins method.

Results

Mean SIA was 0.40 ± 0.28 diopters (D) in the one-handed technique group and 0.39 ± 0.25 D in the two-handed technique group. No statistically significant difference was found in the mean SIA score. The mean torque value was −0.05 ± 0.26 D in the one-handed technique group and 0.11 ± 0.37 D in the two-handed technique group. Mean torque was significantly lower (P<0.05) in the one-handed technique group than in the two-handed technique group.

Conclusion

The results indicate that the corneal side port in two-handed cataract surgery has a rotating effect on the axis of astigmatism.

Residual astigmatism following toric intraocular lens implantation related to pupil size

PURPOSE

To present two patients with residual astigmatism following toric intraocular lens (IOL) implantation.

METHODS

Case reports.

RESULTS

A 58-year-old woman underwent toric IOL implantation (spherical power 29.50 diopters [D], cylinder power 3.00 D; SN60T5, Alcon Laboratories Inc) to correct 2.33 D @ 80° of corneal astigmatism. Postoperatively, uncorrected distance visual acuity (UDVA) was 20/30 and corrected distance visual acuity (CDVA) was 20/22 (0 -1.75 × 95), indicating an overcorrection of astigmatism. Slit-lamp examination demonstrated no IOL misalignment. Wavefront aberrometry showed a large pupil diameter (>6 mm) and a lower corneal astigmatism in a 6-mm zone (-1.40 D @ 174°) compared to a 4-mm zone (-2.21 D @ 171°). The second patient, a 60-year-old man, underwent multifocal toric IOL implantation (spherical power 22.50 D, cylinder power 2.25 D; SND1T4, Alcon Laboratories Inc) to correct 1.51 D @ 173° of corneal astigmatism. Postoperatively, UDVA was 20/50 and CDVA was 20/20 (+0.25 -1.00 × 102), indicating an undercorrection of astigmatism. Slit-lamp examination showed no misalignment.

CONCLUSIONS

Both cases indicate that unexplained residual astigmatism following toric IOL implantation may be the result of multiple factors: the effect of the spherical power and anterior chamber depth on toric IOL calculations, the effect of posterior corneal astigmatism, and the effect of a large pupil size. The first two issues may be compensated for by improving toric IOL calculations. The latter indicates that pupillometry is indicated in relatively young patients who undergo toric IOL implantation.