Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications

Rotational stability of toric intraocular lenses with a newly modified capsular tension ring

PURPOSE

To determine whether a newly modified capsular tension ring (CTR) is effective at preventing toric intraocular lens (TIOL) rotation and misalignment.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

DESIGN

Experimental study.

METHODS

Ten human cadaver eyes were used to test the ease or difficulty of TIOL rotation in the capsular bag under 3 experimental conditions: a TIOL alone, a TIOL with a standard CTR, or a TIOL with a newly modified CTR with indentations in a sinusoidal pattern. Scores for the ease of IOL rotation were compared by using the nonparametric Friedman analysis of variance test. In addition, both anterior and posterior Miyake-Apple views were filmed to observe the rotational stability of TIOLs in the capsular bag under the 3 test conditions.

RESULTS

In the ten eyes of five patients, the rotational stability improved with a standard CTR, but further improvement was statistically observed (P < .05) with the newly modified CTR under all test conditions. This was true for both IOLs used (AcrySof and TECNIS toric IOLs), with or without ophthalmic viscosurgical device, and for either clockwise or counterclockwise rotations.

CONCLUSIONS

A newly designed CTR prototype represents a new technology for improving the rotational stability of a TIOL in the capsular bag. Under all test conditions, the prototype performed significantly better than a standard CTR. The results support the use of this new CTR design to improve the accuracy and refractive success of TIOLs.

Comparison of Preoperative Measurements with Intraoperative Aberrometry in Predicting Need for Correction in Eyes with Low Astigmatism Undergoing Cataract Surgery

Purpose

To determine whether intraoperative aberrometry during cataract surgery measures higher levels of absolute astigmatism than preoperative biometry readings and which method yields a lower, final level of astigmatism if the two do not agree.

Patients and Methods

Retrospective record review of all patients who underwent uncomplicated cataract surgery from February 2015 to May 2019 with planned intraoperative aberrometry. Data analysis included preoperative keratometry, total astigmatism as measured by intraoperative aberrometry, intraocular lens model and power used, and postoperative manifest refraction ≥1 month after surgery. The primary outcome measure was the proportion of patients requiring astigmatism correction (≥0.5 D) when measured by preoperative keratometry vs intraoperative aberrometry. Secondary outcomes included postoperative residual astigmatism, where adjusted preoperative astigmatism fell below the 0.5 D threshold for treatment but the intraoperative measurement was ≥0.5 D or ≥1.0 D.

Results

A total of 451 patient records were evaluated. Intraoperative aberrometry measured statistically higher levels of mean astigmatism than keratometry (0.86 D vs 0.79 D, respectively; P < 0.0001) and significantly greater astigmatism among patients with 0.5–1.5 D of adjusted preoperative astigmatism (P < 0.0001). Significantly more patients qualified for with-the-rule astigmatism correction when measured by intraoperative aberrometry (n=339; 75%) than by preoperative keratometry alone (n=314; 70%); P < 0.03. This difference did not hold for against-the-rule or oblique astigmatism. For patients whose preoperative biometry astigmatism differed from intraoperative biometry, final postoperative astigmatism was lower when corrected if the adjusted preoperative and intraoperative measurements had a vector difference of <0.5 D, but there was no additional benefit in final astigmatism reduction when the vector difference was ≥0.5 D.

Conclusion

Using intraoperative biometry readings can produce lower postoperative astigmatism than using preoperative biometry readings, but caution should be used when interpreting intraoperative readings that disagree with preoperative measurements with a vector magnitude of >0.5 D.

Randomized trial comparing visual outcomes of toric intraocular lens implantation using manual and digital marker

Purpose:

The aim of this study was to compare the visual outcome of participants undergoing toric intraocular lens (IOL) implantation after cataract extraction using manual marking versus digital marking for intraoperative guidance.

Methods:

Randomized controlled trial of participants with cataract and corneal astigmatism of 1.00 D-4.50 D. The eyes were grouped into manual marking (Group 1) and digital marking (Group 2). Preoperative Uncorrected distance visual acuity (UDVA), Corrected distance visual acuity (CDVA), and corneal astigmatism were determined. IOL power and axis of alignment were determined using Barrett toric calculator. Eyes were marked by bubble marker and Mendez ring in group 1 and by VERION (Alcon, Fort Worth, Texas) digital overlay in Group 2. Postoperatively, UDVA, CDVA, residual refractive cylinder and IOL misalignment were determined (iTrace system, Tracey technologies) at 1 week, 6 weeks, and 3 months.

Results:

A total of 61 eyes of 50 participants, 31 in Group 1 and 30 in Group 2, were studied. The mean postoperative cylindrical error was 0.50 ± 0.39 D in Group 1 and 0.29 ± 0.34 D in Group 2 (P = 0.03). 67.74% (n = 21) and 93.55% (n = 29) eyes achieved a residual astigmatism of ≤0.50 D and ≤1.00 D, respectively, in Group 1, whereas 83.33% (n = 25) and 100% (n = 30) eyes achieved a residual astigmatism of ≤0.50 D and ≤1.00 D, respectively, in Group 2 at 3 months postoperatively. Toric IOL misalignment was 4.71 ± 3.12° in Group 1 and 4.03 ± 2.99° in Group 2 (P = 0.39).

Conclusion:

Accurate manual marking and digital marking are equally effective guides for toric IOL alignment, intraoperatively.

Coma Influence on Manifest Astigmatism in Coma-Dominant Irregular Corneal Optics

PURPOSE

To evaluate the influence of coma on manifest refractive cylinder (MRC) in eyes with coma-dominated corneal optics and suggest alternative guidelines for surgical planning of astigmatism correction in topography-guided ablation and toric intraocular lens (IOL) exchange surgery.

METHODS

Twelve eyes with coma-dominant corneal optics and low lenticular astigmatism were selected. The astigmatism remaining after subtraction of total corneal astigmatism (TCA) and lenticular astigmatism from MRC, termed discrepant astigmatism, was calculated and correlated to corneal coma at the anterior surface. Refractive and topography data were then used to simulate topography-guided refractive surgery (topography-guided group) in 7 eyes and lenticular exchange surgery with toric intraocular lens (IOL) implantation (toric IOL group) in 5 eyes. The estimated postoperative MRC after correction of TCA or MRC for each group was compared.

RESULTS

The axis and amplitude of discrepant astigmatism correlated strongly with the axis and amplitude of coma. In the topography-guided group, where topography-guided ablation eliminated corneal higher order aberrations (HOAs), TCA-based correction led to less estimated postoperative manifest astigmatism than MRC-based correction. In the toric IOL group, where removal of the crystalline lens did not affect corneal HOAs, MRC-based correction via toric IOL implantation led to less estimated postoperative astigmatism than TCA-based correction.

CONCLUSIONS

Discrepant astigmatism in eyes with coma-dominant corneal optics correlates with coma. In such eyes, treating TCA, along with corneal HOAs, instead of MRC, seems appropriate in topography-guided treatments, whereas treating MRC may be a better choice in lenticular exchange surgery with toric IOL implantation, where corneal HOAs are not treated. [J Refract Surg. 2021;37(4):274-282.].

Astigmatism correction with toric implantable collamer lens in low and high astigmatism groups

PURPOSE

To analyze the target induced astigmatism (TIA), surgically induced astigmatism (SIA), difference vector (DV), and correction index (CI) in the correction of astigmatism with phakic lenses, and its influence on visual acuity, and to analyze the safety and efficacy indexes of the correction of high and low power astigmatism with toric phakic lenses.

DESIGN

Retrospective comparative study.

METHODS

The medical records of patients that were operated on at the research center during the period were analyzed. Results were divided into Low Astigmatism Group - LAG (33 eyes) and High Astigmatism Group - HAG (93 eyes) according to the implanted toric ICL lens power. Preoperative refraction and resultant postoperative refraction were analyzed by vector analysis. Visual acuity pre and postop, with and without optical correction, were compared.

RESULTS

A total of 126 eyes were studied. The average preop refraction was -5.02 D sphere with -2.61 D cylinder. The average ICL lens power implanted was -8.31 D sphere +2.77 D cylinder. Refractive remaining was -0.01 ± 0.11 D sphere -0.15 ± 0.28 D cylinder. The arithmetic average angle of error in the astigmatism correction was 1.08°. The resultant cylinder was -0.03 ± 0.12 D and -0.19 ± 0.30 D in the low and high astigmatism groups, respectively, with a mean UDVA -0.01 ± 0.10 and 0.01 ± 0.16 and CDVA -0.03 ± 0.08 and -0.01 ± 0.17 for each group. The safety and efficacy indexes for the low astigmatism group were 1.09 ± 0.16 and 1.05 ± 0.17, respectively, with 1.11 ± 0.17 and 1.06 ± 0.16 for the high astigmatism group.

CONCLUSIONS

The correction of astigmatism by the implantation of toric phakic lenses of the posterior chamber is safe and effective, independently of the amount of cylinder corrected.

Rotational stability of modified toric intraocular lens

We evaluated the rotational stability of a new toric intraocular lens (IOL), HOYA XY-1 toric IOL that is an improved version of HOYA 355 toric IOL, with longer overall length (13.0 mm vs. 12.5 mm), shortened unfolding time, and texture processing of the surface of haptics. Data from 193 eyes of 165 patients (76.4 ± 8.3 years old) with preoperative corneal astigmatism exceeding 0.75 diopters who had undergone phacoemulsification and toric IOL implantation were collected and analyzed. Corneal astigmatism, refractive astigmatism, and uncorrected (UDVA) and corrected distance visual acuity (CDVA) were evaluated before and 1 day, 1 week, and 1 month after surgery. The degree of IOL decentration, IOL tilt, and toric axis misalignment was assessed at 1 day and 1 month postoperatively. Fifty eyes received AcrySof toric IOL, 51 eyes TECNIS toric IOL, 46 eyes HOYA 355 toric IOL, and 46 eyes HOYA XY-1 toric IOL. The amount of axis misalignment from the intended axis was significantly different among IOLs (p = 0.004, one-way ANOVA), and HOYA XY-1 showed significantly less amount of axis misalignment than TECNIS (p = 0.020, Tukey’s multiple comparison) and HOYA 355 (p = 0.010). The proportion of eyes that showed axis misalignment <10° at 1 month postoperatively was significantly higher with HOYA XY-1 toric IOL than with other toric IOLs (χ² test, p = 0.020). HOYA XY-1 toric IOL, the modified version of HOYA 355 toric IOL, showed excellent rotational stability in comparison with other models of toric IOLs.

Comparison of surgical repositioning rates and outcomes for hydrophilic vs hydrophobic single-piece acrylic toric IOLs

PURPOSE

To evaluate the comparative rotational stability and the repositioning rates and outcomes of a hydrophilic and hydrophobic acrylic monofocal toric intraocular lens (IOLs).

SETTING

Single center, Aravind Eye Hospital in Madurai, India.

DESIGN

Retrospective cohort study.

METHODS

All patients had either an Auroflex hydrophilic acrylic toric IOL (n = 4603) or AcrySof hydrophobic acrylic toric IOL (n = 926) implanted between January 2015 and April 2019. Surgical repositioning was offered if the toric IOL was 15 degrees or greater misaligned or there was a 2-line or greater improvement in uncorrected distance visual acuity (UDVA) predicted with repositioning.

RESULTS

A total of 5529 single-piece toric IOLs were implanted during the study period. There was no statistically significant difference between the hydrophilic and hydrophobic acrylic toric IOL groups in need for surgical repositioning (2.5% vs 1.9%; P = .34) or actual surgical repositioning rate (1.8% vs 1.5%; P = .59). A higher rate of surgical toric IOL repositioning was associated with younger age (62.7 vs 67.2 years; P < .0001), higher presurgical astigmatism (2.32 vs 1.99 diopters [D]; P < .0001), and with-the-rule astigmatism (4.7% vs 2.1% against-the-rule astigmatism; P = .002). In 95 eyes that underwent toric IOL repositioning, there was significant preoperative to postoperative improvement in UDVA (0.48 vs 0.12 logarithm of the minimum angle of resolution; P < .001), mean residual cylinder (1.79 vs 0.7 D; P < .001), and mean toric IOL misalignment (49.7 vs 5.4 degrees; P < .001). The repositioning outcomes were statistically similar with both toric IOL models. There were no major complications or recurrent toric IOL rotation after surgical repositioning.

CONCLUSIONS

The hydrophilic acrylic toric IOL had comparable rates of postoperative misalignment and surgical repositioning with the hydrophobic acrylic toric IOL. Early postoperative surgical repositioning was both safe and effective with both toric IOLs.

Comparison of the Orientation of the Corneal Steep Meridian Determined by Image-Guided System and Manual Method in the Same Eye

Purpose

To evaluate the difference between the preoperative marking methods for toric intraocular lens (IOL) implantations using an image-guided system (IGS) and the manual marking method in the same eye.

Patients and Methods

In this retrospective case series, 82 patients (101 eyes) who underwent cataract surgery using both manual and IGS (VERION, Alcon  Laboratories) marking were enrolled. First, preoperative reference marks were placed at 6 o’clock and 3 or 9 o’clock position under slit-lamp biomicroscope in the outpatient department using the manual method. Using the reference unit of IGS, the ocular surface data were captured and overlaid. The difference was then measured (preoperative axis misalignment). In the operating room, the orientation of the steep meridian of the manual method was determined based on this reference mark under the surgical microscope. Just before surgery, the digital degree gauge of IGS was overlaid on the ocular surface, and the difference was then measured (total axis misalignment). We calculated the intraoperative axis misalignment by subtracting preoperative axis misalignment from the total axis misalignment.

Results

Mean absolute preoperative, intraoperative, and total axis misalignment values were 3.87±3.95 degrees, 5.46±4.42 degrees, and 4.98±4.49 degrees, respectively. In preoperative, intraoperative, and total misalignment, the ratios of 10 degrees or greater were 10 (14.7%), 12 (17.6%), and 20 (19.8%) eyes, respectively.

Conclusion

The manual method that determines the fixed position of the toric intraocular lens (IOL) may cause large misalignment compared with the IGS, suggesting that using manual method could sometimes result in a large misalignment of toric IOL implantation.

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Corneal Topography for Intraocular Lens Selection in Refractive Cataract Surgery

The purpose of this review is to evaluate the usefulness of corneal topography to select premium intraocular lenses (IOLs), including aspherical IOLs, toric IOLs, and multifocal IOLs, in refractive cataract surgery. Corneal topography can detect corneal regular astigmatism, corneal irregular astigmatism (higher-order aberrations [HOAs]) including spherical aberration, and corneal shape abnormalities after corneal refractive surgery. Surgeons can explain to the patients with significant corneal HOAs about its effect on postoperative visual function before surgery. Multifocal IOLs should not be selected for such eyes. For eyes with abnormal corneal shape, appropriate IOL power calculation formulae can be applied. In the case of toric IOLs, regular astigmatism and corneal HOAs should be checked. Before implanting an aspheric IOL, it is ideal to confirm spherical aberration of the cornea is not below the normal range. Because corneal HOAs, abnormal corneal shape after corneal refractive surgery, corneal regular astigmatism, and corneal spherical aberration increase postoperative refractive errors and poor vision quality with premium IOLs, corneal topography before cataract surgery is helpful in screening patients who are not appropriate candidates for premium IOLs.

[Phacosurgery features in keratoconus]

The review summarizes the results of surgical treatment of cataracts in patients with keratoconus. The major challenges of phacosurgery in keratoconus are associated with intraocular lens (IOL) power calculation, choice of the most appropriate IOL model and additional interventions required to stabilize keratectasia and reduce corneal irregularity.

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.

Clinical outcomes of Ankoris toric intraocular lens implantation using a computer-assisted marker system

PURPOSE

To report the clinical outcomes of patients who underwent cataract surgery with implantation of Ankoris monofocal toric intraocular lens (IOL) (PhysIOL SA, Liège, Belgium) using the Zeiss Callisto Eye (Carl Zeiss AG, Dublin, CA).

METHODS

We conducted a retrospective case series of patients who underwent routine cataract extraction and implantation of Ankoris toric IOL using the Zeiss Callisto eye between January 2018 and December 2018 by four senior surgeons. Patients' medical records were reviewed, and clinical outcomes including postoperative refraction, visual acuity outcomes, IOL position and deviation from planned axis were collected.

RESULTS

Fifty-six eyes of 56 patients were included, 48% were female, and the mean age was 70 ± 8 years. Patients with pseudoexfoliation syndrome, glaucoma or keratoconus were excluded from the study. Pre-operative mean corneal astigmatism was 2.38 ± 0.78 diopters (D), and mean implanted IOL cylindrical power was 3.06 ± 1.07 D. IOL rotation 30 days postoperatively was within 5° in 82% of eyes and between 6° and 10° in 10.8% of eyes. Mean postoperative refractive astigmatism 30 days postoperatively was 0.22 ± 0.36 D; in 84% of eyes the postoperative refractive astigmatism was ≤ 0.50 D. IOL rotation significantly increased between day 1 to day 7 postoperatively (1.91 ± 3.15° to 3.18 ± 3.3°, P = 0.001). However, no significant rotation had occurred between day 7 and day 30 postoperatively (P = 0.093).

CONCLUSION

Cataract surgery with implantation of Ankoris monofocal toric IOL using the Zeiss Callisto Eye marking system is predictable and effective in reducing refractive astigmatism.

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.

Decentration of a toric intraocular lens implant in a patient with simple megalocornea

Purpose

To describe a patient who developed radial displacement of the capsular bag and toric intraocular lens implant within approximately 5 weeks after surgery.

Observations

A patient underwent uncomplicated cataract extraction and implantation of a toric IOL for 2.5 diopters (D) of preoperative corneal astigmatism. Uncorrected visual acuity (UCVA) on postoperative day 1 was 20/20. Blurriness developed 5 weeks after surgery when UCVA was 20/70 but corrected to 20/20 with 2 D of cylinder in a new axis. The IOL was in the proper axis, but it and the capsular bag were radially displaced. Dilated examination revealed posterior capsular opacification superotemporally, outside the visual axis. The patient's biometry revealed axial myopia and megalocornea (white-to-white measurement of 13.44 mm), suggesting a larger than average capsular bag. Surgery was performed at postoperative week 6 to expand the capsular bag using a capsular tension ring and to re-center the IOL keeping the same axis. The patient recovered UCVA of 20/25 after the IOL was recentered.

Conclusions and Importance

It is important to review biometry for large white-to-white measurements. Eyes with megalocornea may require capsular tension rings at time of toric IOL implantation so as to maintain IOL centration and good UCVA.

Effect of 1.8-mm steep-axis clear corneal incision on the posterior corneal astigmatism in candidates for toric IOL implantation

Background

In the present study, we aimed to analyze the effects of cataract surgery using a 1.8-mm steep-axis clear corneal incision (CCI) on the posterior corneal surfaces based on the keratometry from the rotating Scheimpflug imaging device (Pentacam HR) in candidates for toric intraocular lens (IOL) implantation.

Methods

Preoperative and at least 1-month postoperative data measured by Pentacam HR were collected in patients for toric IOL implantation. Surgically induced astigmatism on the posterior cornea (P-SIA) was calculated based on the preoperative and postoperative keratometric data, and the related factors of P-SIA were analyzed.

Results

A total of 60 eyes from 56 patients were enrolled. The preoperative anterior, posterior and total corneal astigmatism was 1.58 ± 0.61 D,0.28 ± 0.22 D and 1.70 ± 0.52 D respectively. The postoperative anterior, posterior and total corneal astigmatism was 1.26 ± 0.68 D, 0.41 ± 0.26 D and 1.30 ± 0.51 D respectively. The astigmatism was significantly decreased on anterior surface (P<0.001, paired t-test) and increased on posterior surface (P<0.001, paired t-test). The mean of P-SIA calculated by Holladay–Cravy–Koch method was 0.34 ± 0.20 D, with 0.5 D or greater accounting for 26.7%. A statistically significant correlation was observed between the P-SIA and preoperative anterior corneal astigmatism (r = 0.29, P = 0.024), as well as preoperative posterior corneal astigmatism (r = 0.27, P = 0.038). Multivariate regression analysis showed the preoperative anterior and posterior corneal astigmatism had a significant effect on P-SIA (F = 7.344, P = 0.001).

Conclusions

In candidates for toric IOL implantation with a 1.8-mm steep-axis CCI, the incision caused a significant reduction of the anterior corneal astigmatism but an increase of the posterior corneal astigmatism. P-SIA could not be ignored, and it played a significant role in SIA, especially in cases with higher preoperative anterior or posterior corneal astigmatism.

Management of Cataract in Patients with Irregular Astigmatism with Regular Central Component by Phacoemulsification Combined with Toric Intraocular Lens Implantation

Purpose

To evaluate visual acuity (VA) and refractive status in patients with cataract and irregular astigmatism with a regular central component after phacoemulsification with implantation of a toric intraocular lens (IOL).

Methods

Patients with cataract associated with irregular astigmatism with a regular central component were enrolled. All patients underwent phacoemulsification and toric IOL implantation. Postoperative visual acuity, residual astigmatism, toric IOL rotation, higher-order aberration, and objective and subjective visual quality were measured 3 months after surgery.

Results

Twenty-three eyes were included in the study. The logMAR corrected and uncorrected distance visual acuity values were decreased at 3 months postoperatively (p  <  0.005). The preoperative average corneal astigmatism and postoperative residual astigmatism were 1.15–6.97 D (1.99 ± 1.26 D) and 0–2.75 D (0.65 ± 0.57 D), respectively. The average IOL rotation was 3.17 ± 2.01°. Some objective indicators of visual quality, including the modulation transfer function (p  <  0.05), Strehl ratio (p  <  0.005), 100% VA (p  <  0.005), 20% VA (p  <  0.005), and 9% VA (p  <  0.005), were significantly higher than the corresponding preoperative values. The objective scatter index (p  <  0.005) was significantly lower than that before surgery. The postoperative VF-14 scale score was 83.99 ± 14.58.

Conclusion

Toric IOL implantation has a good corrective effect on certain specific types of corneal irregular astigmatism with cataract. This effect can be attributed to its ability to correct the regular component of irregular astigmatism. The indications for toric IOL implantation could be expanded to some extent, thereby bringing benefit to more patients.

Outcome of toric intraocular lenses implanted in eyes with previous corneal refractive surgery

PURPOSE

To evaluate the outcome of toric intraocular lens (IOL) implantation in eyes with previous laser in situ keratomileusis/photorefractive keratectomy (LASIK/PRK).

SETTING

Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA.

DESIGN

Retrospective case series.

METHODS

Consecutive cases that had previous myopic or hyperopic LASIK/PRK and had undergone cataract surgery with toric IOL implantation were retrospectively reviewed. Included were eyes that had (1) preoperative ocular biometry measurements with the Lenstar, (2) no intraoperative or postoperative complications, and (3) available postoperative manifest refraction at ≥3 weeks with corrected distance visual acuity of 20/30 or better. Vector analysis was used to assess the preoperative corneal and postoperative refractive astigmatism.

RESULTS

In 56 eyes with previous myopic LASIK/PRK and 19 eyes with previous hyperopic LASIK/PRK, respectively, the mean magnitudes of corneal astigmatism were 1.34 ± 0.62 diopters (D) and 1.66 ± 0.80 D, 5% and 0% of eyes had anterior corneal astigmatism ≤0.50 D, and the centroid values were 0.31 D at 19 degrees ± 1.45 D and 0.74 D at 92 degrees ± 1.72 D preoperatively. Postoperatively, the mean magnitudes of refractive astigmatism were 0.36 ± 0.31 D and 0.34 ± 0.34 D, 80% and 84% of eyes had refractive astigmatism of ≤0.50 D, and the centroid values were 0.12 D at 152 degrees ± 0.46 D and 0.05 D at 172 degrees ± 0.48 D (all P < .05).

CONCLUSIONS

Toric IOLs were effective to correct preexisting corneal astigmatism in eyes with previous excimer laser corneal refractive surgery.

Automated refraction after trifocal and trifocal toric intraocular lens implantation

BACKGROUND

To analyze the correlation between automated refraction and manifest refraction after implantation of a trifocal intraocular lens or its toric version.

METHODS

This cross-sectional study involved 105 eyes of 105 patients. Subjects were divided in two groups: 62 with trifocal (AcrySof PanOptix) and 43 with trifocal toric (AcrySof PanOptix Toric) intraocular lenses. Automated refraction was employed as starting point for obtaining the manifest refraction. Automated refraction and manifest refraction measurements were analyzed and compared using the vector analysis 3 months after the surgery.

RESULTS

In both groups, the higher differences between automated refraction and manifest refraction measurements were found for the cylinder and the spherical equivalent (M). Cylinder values for PanOptix were: -0.60 ± 0.36 D with automated refraction and -0.17 ± 38 D with manifest refraction (p < 0.001); for PanOptix Toric, the values were: -0.49 ± 0.31 D with automated refraction and -0.05 ± 0.21 D with manifest refraction (p < 0.001). M values for PanOptix were: -0.23 ± 0.31 D with automated refraction and -0.03 ± 0.16 D with manifest refraction (p < 0.001); for PanOptix Toric, the values were: -0.13 ± 0.40 D with automated refraction and 0.01 ± 0.12 D with manifest refraction (p < 0.001). For the PanOptix group, intraclass correlation coefficients were: 0.51 (sphere), 0.64 (cylinder), 0.42 (M), 0.62 (J0), and 0.37 (J45). For the PanOptix Toric group, the intraclass correlation coefficients were: 0.39 (sphere), 0.61 (cylinder), 0.39 (M), 0.53 (J0), and 0.09 (J45).

CONCLUSION

The results of this study suggest that patients implanted with the trifocal and the trifocal toric intraocular lens under study showed similar automated refraction results between them, with a slight trend to more negative amounts of cylinder and M. Nevertheless, clinicians should carefully confirm all parameters of the refraction with manifest refraction.

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.

Refractive Outcomes After Trabecular Micro-Bypass Stents (iStent Inject) with Cataract Extraction in Open-Angle Glaucoma

Purpose

Simultaneous cataract and glaucoma surgery has traditionally been challenging for the anterior segment surgeon. The introduction of minimally invasive glaucoma surgery (MIGS) in conjunction with cataract surgery appears safe and effective in lowering intraocular pressure. Although a significant visual impact leading from the combined procedure is unexpected, we aim to describe the refractive outcomes in a cohort of patients undergoing simultaneous cataract removal and iStent inject and discuss the potential implications of combined surgery in patients with co-existent glaucoma.

Patients and Methods

This is a retrospective consecutive case series inclusive of patients undergoing combined femtosecond laser-assisted cataract surgery and the insertion of two trabecular micro-bypass stents (iStent inject). Visual acuity, refraction and astigmatic vector analysis were collated and analysed from the preoperative and 4 weeks postoperative visits.

Results

One hundred and six eyes of 89 patients from 2 surgeons were included in the original cohort. The mean absolute difference from target refraction was 0.36 ± 0.25D. 73.9% of eyes were within ± 0.5D of the refractive target and 98.9% of eyes were within ± 1.00D. 73.8% of eyes had 0.5D or less residual refractive astigmatism following the procedure.

Conclusion

We present a novel cohort of glaucoma patients undergoing combined trabecular micro-bypass stents (iStent inject) and cataract surgery achieving excellent refractive outcomes. The results of this study indicate that this second-generation device is refractively neutral.

Visual and autorefraction outcomes following toric intraocular lens insertion without calculation of posterior corneal astigmatism in the UK National Health Service

OBJECTIVE

To ascertain visual and refractive outcomes following toric intraocular lens (IOL) implantation in the UK National Health Service (NHS) without posterior corneal astigmatism calculation, with multiple surgeons of different grades, pooled input and output pathways and autorefraction as the refractive outcome measure.

METHODS

Preoperative and 1-month post-operative data were analysed retrospectively in 114 eyes (95 patients) receiving a toric IOL between 2014 and 2016 at Imperial College NHS Trust. Preoperative keratometric astigmatism was ≥2 dioptres (D).

RESULTS

Mean preoperative best-corrected visual acuity (BCVA) was 0.50 logMAR (±0.46), improving to a mean uncorrected VA (UCVA) of 0.35 logMAR (±0.36) postoperatively (p < 0.001) with 65% of eyes attaining a UCVA ≤ 0.30 logMAR. Excluding 33 eyes with pre-existing visual comorbidities and one targeting monovision, mean post-operative UCVA was 0.24 logMAR (±0.29) (p < 0.001), and 85% had UCVA ≤ 0.30 logMAR, 62% UCVA ≤ 0.20 logMAR. Mean refractive astigmatism improved from 3.04 D (±1.46) to 1.36 D (±1.13) (p < 0.001). In total, 52% of eyes had post-operative refractive astigmatism ≤1.00 D. The Alpins correction index was 1.05 (±0.22), indicating a tendency to overcorrect. Toric IOL misalignment was noted in two eyes, and two cases of posterior capsule rupture were converted to a non-toric IOL.

CONCLUSIONS

Visual outcomes of toric IOL implantation in our pooled pathway are comparable to single-surgeon case series where posterior corneal astigmatism has not been accounted for. However, with 1-month post-operative autorefraction, only 52% of eyes had ≤1 D refractive astigmatism, which is lower than previously published series, but may be standard for 1-month autorefraction outcomes.

Comparative clinical outcomes of Tecnis toric IOL implantation in femtosecond laser-assisted cataract surgery and conventional phacoemulsification surgery

AIM

To compare the short-term visual outcomes, residual refractive cylinder, and rotation stability after Tecnis toric intraocular lens (IOL) implantation during femtosecond laser-assisted cataract surgery (Femto phaco) and conventional phacoemulsification surgery (Conventional phaco).

METHODS

In a prospective cohort study, Conventional phaco and Femto phaco (anterior capsulotomy and lens fragmentation by a femtosecond laser) with Tecnis toric IOL implantation were performed in 40 eyes from 36 patients and 37 eyes from 33 patients, respectively. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refraction were assessed during 1d, 1wk, and 1mo follow-ups. The orientation of the Tecnis Toric IOL was evaluated during 1wk and 1mo follow-ups.

RESULTS

There were no significant differences in UDCA or CDVA between two groups at 1mo postoperatively, though relatively more subjects had UDVA values of 20/25 or better in Femto phaco group than in the Conventional group (P>0.05). A lower but not significantly lower rate of having more than 5° of IOL rotation was observed in Femto phaco group at the 1-month follow-up, while a significant lower rate of residual astigmatism of ≤1 D was observed in Femto phaco group.

CONCLUSION

The Femto phaco group has significantly more subjects with the residual astigmatism of ≤1 D, but there are no significant differences in rotation stability and visual outcomes as compared with the Conventional phaco group after the application of the Tecnis toric IOL in this cohort.

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

PURPOSE

To compare the accuracy of toric intraocular lens (IOL) alignment using the Verion Image-Guided System versus a conventional manual ink-marking procedure.

SETTING

University Eye Clinic Maastricht, Maastricht, the Netherlands.

DESIGN

Prospective randomized clinical trial.

METHODS

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.

RESULTS

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 1 hour (1.3 degrees ± 1.6 [SD] versus 2.8 ± 1.8 degrees; P = .02) and 3 months (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 ± 0.10 logarithm of minimum angle of resolution (logMAR) and 0.04 ± 0.09 logMAR, respectively (both P > .05). No intraoperative complications occurred during any surgery.

CONCLUSION

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.

Comparison of astigmatic prediction errors associated with new calculation methods for toric intraocular lenses

PURPOSE

To compare the prediction errors in residual astigmatism associated with new calculation methods for toric intraocular lenses (IOLs).

SETTING

Hospital da Luz, Lisbon, Portugal.

DESIGN

Retrospective case series.

METHODS

In eyes having cataract surgery with toric IOL implantation (Acrysof IQ), the predicted residual astigmatism by each calculation method was compared with the manifest refractive astigmatism. The prediction error in residual astigmatism was calculated by vector analysis.

RESULTS

The study evaluated 86 eyes (86 patients). All calculation methods resulted in overcorrection of with-the-rule astigmatism and undercorrection of against-the-rule astigmatism. For the original Alcon calculator, the centroid prediction error was 0.43 @ 170, which was reduced by the application of the Baylor nomogram (0.35 @ 169) or the Abulafia-Koch formula (0.34 @ 170). For the Holladay toric calculator, the centroid prediction error was 0.40 @ 168, which was reduced by the Baylor nomogram (0.35 @ 169), the Abulafia-Koch formula (0.25 @ 158), and the Goggin coefficient of adjustment (0.38 @ 170). The Barrett calculator and the newly introduced Alcon calculator yielded the lowest centroid prediction errors (0.17 @ 165 and 0.19 @ 164, respectively). The centroid prediction error of ray-tracing calculations (PhacoOptics) using real posterior corneal surface measurements was 0.32 @ 171.

CONCLUSIONS

The Barrett toric calculator and the new Alcon calculator yielded the lowest astigmatic prediction errors. Of the nomogram methods, application of the Abulafia-Koch formula achieved the best results. The outcomes of toric IOL implantation might be improved by using 1 of these calculation methods.

Toric intraocular lens versus limbal relaxing incisions for corneal astigmatism after phacoemulsification

BACKGROUND

Cataract is the leading cause of blindness in the world, and clinically significant astigmatism may affect up to approximately 20% of people undergoing cataract surgery. Pre-existing astigmatism in people undergoing cataract surgery may be treated, among other techniques, by placing corneal incisions near the limbus (limbal relaxing incisions or LRIs) or by toric intraocular lens (IOLs) specially designed to reduce or treat the effect of corneal astigmatism on unaided visual acuity.

OBJECTIVES

To assess the effects of toric IOLs compared with LRIs in the management of astigmatism during phacoemulsification cataract surgery.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register; 2019, Issue 9); Ovid MEDLINE; Ovid Embase and four other databases. The date of the search was 27 September 2019.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing toric IOLs with LRIs during phacoemulsification cataract surgery.  DATA COLLECTION AND ANALYSIS: We used standard methods expected by Cochrane. We graded the certainty of the evidence using GRADE. Our primary outcome was the proportion of participants with postoperative residual refractive astigmatism of less than 0.50 dioptres (D) six months or more after surgery. We also collected data on mean residual refractive astigmatism. Secondary outcomes included: uncorrected distance visual acuity, vision-related quality of life, spectacle independence and adverse effects including postoperative lens rotation requiring re-alignment. To supplement the main systematic review assessing the effects of toric IOLs compared with LRIs in the management of astigmatism during phacoemulsification cataract surgery, we sought to identify economic evaluations on the subject.

MAIN RESULTS

We identified 10 relevant studies including 517 people (626 eyes). These studies took place in China (three studies), UK (three), Brazil (one), India (one), Italy (one) and Spain (one). The median age of participants was 71 years. The level of corneal astigmatism specified in the inclusion criteria of these studies ranged from 0.75 D to 3 D. A variety of toric IOLs were used in these studies, in all but one study, these were monofocal. Studies used three different nomograms to determine the size and placement of the LRI. Two studies did not specify this. None of the studies were at low risk of bias in all domains, but two studies were at low risk of bias in all domains except selective outcome reporting, which was unclear. The remaining studies were at a mixture of low, unclear or high risk of bias. People receiving toric IOLs were probably more likely to achieve a postoperative residual refractive astigmatism of less than 0.5 D six months or more after surgery (risk ratio (RR) 1.40, 95% confidence interval (CI) 1.10 to 1.78; 5 RCTs, 262 eyes). We judged this to be moderate-certainty evidence, downgrading for risk of bias. In the included studies, approximately 500 eyes per 1000 achieved postoperative astigmatism less than 0.5 D in the LRI group compared with 700 per 1000 in the toric IOLs group. There was a small difference in residual astigmatism between the two groups, favouring toric IOLs (mean difference (MD) -0.32 D, 95% CI -0.48 to -0.15 D; 10 RCTs, 620 eyes). Although all studies favoured toric IOLs, the results of individual studies were inconsistent (range of effects -0.02 D to -0.71 D; I² = 89%). We considered this to be low-certainty evidence, downgrading for risk of bias and inconsistency. People receiving a toric IOL probably have a small improvement in visual acuity at six months or more after surgery compared to people receiving LRI, but the difference is small and probably clinically insignificant (MD -0.04 logMAR, 95% CI -0.07 to -0.02; 8 RCTs, 474 eyes; moderate-certainty evidence). Low-certainty evidence from one study of 40 people suggested little difference in vision-related quality of life measured using the Visual Function Index (VF-14) (MD -3.01, 95% CI -8.56 to 2.54). Two studies reported spectacle independence and suggested that people receiving toric IOLs may be more likely to be spectacle independent (RR 1.56, 95% CI 1.14 to 2.15; 100 people; low-certainty evidence). There were no cases of lens rotation requiring surgery (very low-certainty evidence). Five studies (320 eyes) commented on a range of other adverse effects including corneal oedema, endophthalmitis and corneal ectasia. All these studies reported that there were no adverse events with the exception of one study (40 eyes) where one participant in the LRI group had a central de-epithelisation which recovered over 10 days. We found no economic studies that compared toric IOLs with LRIs.

AUTHORS' CONCLUSIONS

Toric IOLs probably provide a higher chance of achieving astigmatism within 0.5 D after cataract surgery compared with LRIs. There may be a small mean difference in postoperative astigmatism, favouring toric IOLs, but this difference is likely to be clinically unimportant. There was no evidence of an important difference in postoperative visual acuity or quality of life between the techniques. Evidence on adverse effects was uncertain. The apparent shortage of relevant economic evaluations indicates that economic evidence regarding the costs and consequence of these two procedures is currently lacking.

Refractive and Visual Outcomes and Rotational Stability of Toric Intraocular Lenses in Eyes With and Without Previous Ocular Surgeries: A Longitudinal Study

PURPOSE

To evaluate visual and refractive outcomes and rotational stability of toric intraocular lens (IOL) implantation in eyes with previous ocular surgeries.

METHODS

This controlled, longitudinal cohort study included a total of 133 eyes (59 study cases with a history of corneal, vitreoretinal, and/or glaucoma surgery and 74 randomly selected controls without a history of ocular surgery) that had cataract and corneal astigmatism treated with toric IOL implantation. Postoperative outcomes were recorded at postoperative 1 month and 3 to 12 months.

RESULTS

Refractive prediction errors were within ±1.00 diopter (D) of target in 93.5% and 88.4% of the study cases at postoperative 1 month and 3 to 12 months, respectively. They were within ±0.50 D of target in 56.5% and 60.5% of the cases during the same follow-up intervals, respectively. Study cases showed statistically significantly inferior uncorrected distance visual acuity (UDVA) compared to controls at 1 month postoperatively (0.27 ± 0.24 and 0.17 ± 0.21 logMAR, respectively, P = .027) but not during the later follow-up (0.19 ± 0.19 and 0.16 ± 0.19 logMAR, respectively, P = .431). Corrected distance visual acuity (CDVA) was slightly lower in the study cases than in controls at 1 month postoperatively (0.13 ± 0.16 and 0.07 ± 0.14, respectively, P = .005) and subsequent follow-up months (0.10 ± 0.13 and 0.03 ± 0.10, respectively, P < .001). Of the examined study cases, 93.9% and 88.4% had IOL axes within 5° of intended axis at postoperative 1 month and 3 to 12 months, respectively.

CONCLUSIONS

Toric IOLs provided significant and sustained improvement in visual acuity and refraction in eyes with a history of prior ophthalmic surgery. Refractive outcomes achieved postoperatively were comparable to those in eyes without a prior history of ophthalmic surgery, although the rate of visual recovery may be different. [J Refract Surg. 2019;35(12):781-788.].

Toric IOL positioning with a no-touch head-up display axis alignment

PURPOSE

To compare a new no-touch alignment technique for toric intraocular lenses (IOL) with the conventional technique that uses a manual pendulum.

METHODS

In this retrospective case-control study, patients who underwent toric IOL implantation using two different alignment techniques (digital Callisto^® system vs. manual-pendulum-based marking) were compared in a vector analysis using the Alpins method and an analysis of variance regarding corrected and uncorrected visual acuity and the deviation of the achieved IOL axis from the targeted axis.

RESULTS

Sixty-one eyes were included into analysis. Thirty-six of these surgeries were performed via the Callisto^® system and 25 eyes via pendulum-based corneal markings. Median IOL axis misalignment was 3° in both groups. Median uncorrected distance visual acuity was 0.097 logMAR versus 0.200. Median best-corrected visual acuity was 0.000 logMAR versus 0.097. All these data were below the range of statistical significance (p > 0.05). Vector analysis showed no significant difference for TIA [median of 3.14 diopters (D) vs. 2.73 D], SIA (median of 3.82 D vs. 3.79 D), DV (1.18 D vs. 1.08 D), and CI (1.23 vs. 1.29). Median angle of error was 1.96° versus - 0.44° (p > 0.05).

CONCLUSIONS

We found no significant difference in the refractive results, the IOL positioning, and the best-corrected and uncorrected distance visual acuity between the two compared methods. Nevertheless, the Callisto^® IOL alignment system delivers a standardized and easy-to-use technology. In particular, less-experienced surgeons might benefit from this marking technique.

Quality of images with toric intraocular lenses

PURPOSE

To objectively evaluate the image quality obtained with toric intraocular lenses (IOLs) when misaligned from the intended axis.

SETTING

University Eye Clinic and the Department of Industrial and Information Engineering, University of Trieste, Trieste, Italy.

DESIGN

Experimental study.

METHODS

An experimental optoelectronic test bench was created. It consisted of a high-resolution monitor to project target images and an artificial eye. The system simulates the optical and geometric characteristics of the human eye with an implanted toric IOL. A 3.00 diopters corneal astigmatism was simulated. Images reproduced by the optical system were captured according to different IOL axis positions. The quality of each image was analyzed using the visual information fidelity (VIF) criterion. The VIF reduction was calculated at each IOL rotational step.

RESULTS

A 5-degree IOL axis rotation from the intended position determined a decay in the image quality of 7.03%. Ten degrees of IOL rotation caused an 11.09% decay of relative VIF value. For a 30-degree rotation, the VIF decay value was 45.85%. Finally, the image decay with no toric correction was 56.70%.

CONCLUSIONS

The more the objective quality of the image decays progressively, the further the axis of the IOL is rotated from its intended position. The reduction in image quality obtained after 30 degrees of toric IOL rotation was less than 50% and after 45 degrees, the image quality was the same as that of no toric correction.

Evaluation of an intraoperative toric intraocular lens alignment system using an image-guided system

PURPOSE

To evaluate an intraoperative toric intraocular lens (IOL) alignment system using a dedicated operating microscope with an image-guided system without preoperative corneal marking.

SETTING

Vienna Institute for Research in Ocular Surgery, Department of Ophthalmology, Hanusch Hospital, Vienna, Austria.

DESIGN

Prospective case series.

METHODS

In this prospective study, a new operating microscope system was used for cataract surgery (toric IOL alignment system of the OPMI Lumera 700 microscope and CALLISTO eye software). This system allows toric IOL alignment by matching limbal vessels from a preoperative photograph with the live image of the microscope. The preoperative photograph was taken with IOLMaster 500, which included a "Reference Image Attachment" system (red-free image), and this was used to track and follow the eye during surgery. After surgery, rotational alignment was assessed and compared with the preoperative axis calculation. At 1 hour postoperatively, a retroilluminaton photograph was taken, and then rotational alignment was compared with the preoperative axis calculation to see the rotational stability.

RESULTS

Fifty eyes of 50 patients were included. The feasibility of the intraoperative marking was high. Deviation between the postoperative (at the end of surgery in the operating room) and aimed IOL axes was 0.52 degrees ± 0.56 (SD). The deviation between 1 hour postoperatively and the aimed IOL axes was 5.10 ± 4.45 degrees.

CONCLUSION

Intraoperative toric IOL alignment using an image-guided system was an accurate and fast procedure resulting in precise toric IOL alignment, and the system simplified the positioning of toric IOLs. There was a slight rotation of IOLs shortly after surgery (within the first hour).

Performance of the Barrett Toric Calculator with and without measurements of posterior corneal curvature

BACKGROUND

Toric intraocular lens power calculators, e.g., the Barrett Toric Calculator, based on predicted, rather than on measured posterior corneal curvature have yielded the best results so far. However, recent update of the Barrett Toric Calculator aims to fine tune its refractive predictions with the input of measured posterior corneal curvature. Here, we wanted to compare refractive predictions of the Barrett Toric Calculator, based on IOL Master 700 biometry, with and without measurements of posterior corneal curvature.

METHODS

In total 30 eyes were included in the study. One-month postoperative manifest refraction and predicted residual refractive error of both formulas were utilized to calculate mean absolute error and centroid error in predicted residual astigmatism. The Pentacam was used to measure posterior corneal curvature.

RESULTS

We did not find any statistically significant difference in mean absolute error and centroid error in predicted residual astigmatism between the Barrett Toric Calculator with and without measurement of posterior corneal curvature. Post-hoc analysis of with-the-rule and against-the-rule astigmatic eyes did not reveal any significant differences as well.

CONCLUSIONS

Astigmatism prediction errors, based on IOL Master 700 biometry, with and without measured posterior corneal curvature, were similar. To the best of our knowledge, the updated Barrett Toric Calculator is the first formula to provide non-inferior and reliable predictions based on measurement of posterior corneal curvature.

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.

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.

Phacoemulsification With 3.0 and 2.0 mm Opposite Clear Corneal Incisions for Correction of Corneal Astigmatism

PURPOSE

To compare the effect of 3.0 and 2.0 mm opposite clear corneal incisions (OCCIs) in phacoemulsification on reduction of preexisting corneal astigmatism, and their impact on corneal aberrations.

METHODS

This study is a prospective randomized controlled study that included 140 patients with age-related cataract and regular corneal astigmatism ≥0.75 diopter (D). Phacoemulsification was performed using on-meridian 3.0 or 2.0 mm corneal incision with or without an OCCI. Cases were divided into 4 groups: 3.0 mm OCCIs, 3.0 mm single clear corneal incision (3.0 mm SCCI), 2.0 mm OCCIs, and 2.0 mm SCCI. Keratometry and topography were performed at 3 months postoperatively. The variations in corneal astigmatism and aberrations were recorded. Surgically induced astigmatism was calculated using vector analysis.

RESULTS

The corneal astigmatism reduction was 0.61 ± 0.38 D in the 3.0 mm OCCIs group, significantly higher than the other groups (P ≤ 0.004); and 0.29 ± 0.29 D in the 2.0 mm OCCIs group. The mean surgically induced astigmatism was 1.07 ± 0.51 D in the 3.0 mm OCCIs group, higher than 0.61 ± 0.35 D in the 2.0 mm OCCIs group (P = 0.001). The root mean square values of corneal trefoil, spherical aberration, and total higher order aberrations increased at 3 months postoperatively, but there were no significant differences between OCCI and SCCI groups.

CONCLUSIONS

On-meridian 3.0 mm OCCIs are effective for correcting mild-to-moderate corneal astigmatism during cataract surgery, exerting no additional impact on corneal aberration compared with SCCI.

Comparison of incidence of repositioning surgery to correct misalignment with three toric intraocular lenses

PURPOSE

To compare the incidence of re-orientating surgery to improve misalignment of three models of acrylic toric intraocular lenses: AcrySof toric intraocular lens (Alcon Laboratories, Inc.), TECNIS toric intraocular lens (Johnson & Johnson Vision, Inc.) and HOYA 355 toric intraocular lens (HOYA).

METHODS

In this retrospective, multicenter case series, medical charts were reviewed for collecting data on realignment surgery of toric intraocular lenses at 10 ophthalmic surgical sites in Japan.

RESULTS

Over all, intraocular lens repositioning surgery was conducted in 89 of 9430 eyes (0.944%) at an average of 10.5 ± 9.7 days after the initial cataract surgery. The incidence was 0.213% (11/5155), 1.797% (62/3451) and 1.942% (16/824) with AcrySof, TECNIS and HOYA toric intraocular lenses, respectively. The incidence was significantly lower with AcrySof than with other two brands of toric intraocular lenses (p < 0.0001). In those eyes which underwent reorientation surgery, the amount of misalignment was 26.4 ± 21.9°, 29.7 ± 15.4° and 28.1 ± 20.7° with AcrySof, TECNIS and HOYA toric intraocular lenses, respectively; there was no significant difference among groups (p = 0.821). The repositioning surgery significantly reduced misalignment in all three groups.

CONCLUSION

The rotational stability was considerably different among toric intraocular lenses of different manufacturers. The incidence of repositioning surgery was significantly lower with AcrySof than with TECNIS and HOYA toric intraocular lenses.

Improving toric intraocular lens calculations using total surgically induced astigmatism for a 2.5 mm temporal incision

PURPOSE

To determine in cataract surgery the total surgically induced astigmatism (SIA) that accounts for all factors that contribute to the difference between preoperative keratometric and postoperative refractive astigmatism other than any toricity of an intraocular lens (IOL).

SETTING

Twenty surgical sites in the United States.

DESIGN

Retrospective case series.

METHODS

An analysis was performed of 4 clinical trials involving toric IOLs and nontoric IOLs in standard cataract surgery. Data included preoperative keratometry and manifest refraction measurements at multiple postoperative visits. For each eye with a nontoric IOL, the total SIA vector was calculated as the vector difference between postoperative refractive and preoperative keratometric astigmatism. The relationship between the total SIA vector and meridian of preoperative keratometric astigmatism was determined and used to develop a new calculation algorithm for toric IOL implantation. The algorithm was tested retrospectively to identify optimum candidate eyes for various cylinder power toric IOLs as well as to compare results with the Barrett toric calculator.

RESULTS

The total SIA vector was a significant contributor to surgically associated astigmatic changes in eyes receiving nontoric IOLs. The total SIA vector was dependent on the preoperative steep meridian in a consistent fashion, allowing development of a new calculation algorithm for toric IOL correction. Retrospectively applying this algorithm to toric IOL cases led to significantly improved differences between toric and nontoric control populations.

CONCLUSIONS

Total SIA analysis is a new approach for toric IOL surgery. Because it considers all factors that may influence outcomes, the total SIA is a useful inclusion in toric IOL surgical planning.

Comparison of clinical outcomes of toric intraocular lens, Precizon vs Tecnis: a single center randomized controlled trial

Background

To compare the clinical outcome of Precizon toric intraocular lens (IOL) (Ophtec Inc.) to that of Tecnis toric IOL (Abbott Medical Optics Inc.).

Methods

This randomized comparative study included 40 eyes (Precizon, 20 eyes; Tecnis, 20 eyes) of 40 patients with visually significant cataract and corneal astigmatism who underwent cataract surgery. Changes in uncorrected distant visual acuity (UCDVA), best corrected distant visual acuity (BCDVA), uncorrected intermediate visual acuity (UCIVA), refraction, residual astigmatism, rotation of the IOL axis, and higher order aberrations at 3 months postoperatively were evaluated. Vector analysis was performed using the Alpins method.

Results

Both groups showed significant reduction in refractive astigmatism after the surgery (Precizon: − 1.06 ± 0.94 Diopter (D) to − 0.31 ± 0.29 D, p = 0.042; Tecnis: − 1.83 ± 1.29 D to − 0.41 ± 0.33 D, p = 0.015). There was no significant (p > 0.05) difference in postoperative UCDVA, BCDVA, or residual astigmatism between the two groups, although a tendency of better UCIVA was observed in the Precizon group. Vector analysis parameters showed no statistically significant difference beween groups(P > 0.05). Significant difference in rotation of toric IOL axis was found between the two groups (Precizon: 1.50° ± 0.84, Tecnis: 2.56° ± 0.68, p = 0.010). Spherical aberration in the Precizon group was significantly (p = 0.005) lower than that in the Tecnis group.

Conclusions

The Precizon toric IOL group had better rotational stability at 3-month postoperatively. Both Precizon toric IOL and Tecnis toric IOL could be effectively used by cataract surgeons to correct preexisting corneal astigmatism through cataract surgery.

Trial registration

http://clinicaltrials.gov, NCT03085901, retrospectively registered on 21 March 2017.

Electronic supplementary material

The online version of this article (10.1186/s12886-018-0955-3) contains supplementary material, which is available to authorized users.

Comparison of visual performance of toric vs non-toric intraocular lenses with same material

Aim

We compared the visual performance of toric intraocular lenses (IOLs) and non-toric IOLs made of the same material.

Patients and materials:

The subjects included patients implanted with either Acrysof IQ^® toric IOLs (SN6AT3-9) or Acrysof IQ^® IOLs (SN60WF) bilaterally. The toric group included 103 patients who were implanted with Acrysof IQ toric IOLs bilaterally. The non-toric group was a corneal astigmatism-matched control group and included 103 patients who were implanted with Acrysof IQ IOLs bilaterally.

Results

The uncorrected distance visual acuity was significantly better in the toric group, whereas the uncorrected 50 cm visual acuity was better in the non-toric group. There was no significant difference in contrast sensitivity (with and without glare) between both the groups. The rate of spectacle dependency for distance vision was significantly lower in the toric group. There were no significant differences between the two groups in all items of the postoperative quality-of-vision questionnaire (25-item Visual Function Questionnaire).

Conclusion

The toric IOLs used in this study reduced spectacle dependency more than the non-toric IOLs and did not compromise the subjective visual function, but the uncorrected 50 cm vision was worse in toric IOL implanted eyes.

Residual astigmatism after toric intraocular lens implantation: Analysis of data from an online toric intraocular lens back-calculator

PURPOSE

To evaluate some possible causes for residual astigmatism after toric intraocular lens (IOL) implantation based on an analysis of data from an online toric IOL back-calculator.

DESIGN

Retrospective data review.

METHODS

An online toric back-calculator was designed to allow users to input preoperative toric planning information along with postoperative IOL orientation and refractive results. These were then used to determine the optimum orientation of the IOL to reduce refractive astigmatism. The collected aggregate data were extracted from this calculator to investigate the associated reasons for residual astigmatic refractive error with toric IOLs.

RESULTS

The study analyzed 12 812 records with a mean postoperative refractive astigmatism of 1.89 diopters (D). Refractive astigmatism was significantly higher with higher IOL cylinder power (P < .01) but was not different by IOL manufacturer. Ninety percent of IOLs were not at the ideal orientation, despite 30% being at the preoperative calculated orientation. Misalignment showed a directional bias for some IOLs but not for others. The mean calculated percentage reduction in residual cylinder after reorientation was 50% ± 31% (SD), with the magnitude of residual astigmatism after IOL reorientation expected to be 0.50 D or less in 37% of eyes (4835/12 812). Expected outcomes were significantly different by IOL type.

CONCLUSIONS

Analysis of data from the online toric back-calculator provided insights into the nature of residual astigmatism after toric IOL implantation. The reasons for residual astigmatism in this data set varied by IOL type.

FINANCIAL DISCLOSURE

Proprietary or commercial disclosures are listed after the references.

Toric intraocular lenses in eyes with with-the-rule, against-the-rule, and oblique astigmatism: One-year results

PURPOSE

To assess 1-year clinical results of toric intraocular lenses (IOLs) in eyes having with-the-rule (WTR), against-the-rule (ATR), or oblique corneal astigmatism.

SETTING

Four ophthalmic surgical sites, Japan.

DESIGN

Prospective case series.

METHODS

One of 3 toric IOLs or 1 nontoric IOL was implanted in eyes having phacoemulsification and IOL implantation.

RESULTS

The study comprised 218 eyes (155 patients). Based on the suggestion of an online toric calculator with anterior corneal curvature data, 63 eyes received the SN6AT3 IOL with a cylinder power of 1.50 diopters [D] at IOL plane (1.50 D cylinder IOL) 55 eyes the SN6AT4 IOL with a cylinder power of 2.25 D at IOL plane (2.25 D cylinder IOL), and 58 eyes the SN6AT5 IOL with a cylinder power of 3.00 D at IOL plane (3.00 D cylinder IOL) (all Acrysof IQ toric), and 42 eyes received the SN60WF IOL (nontoric IOL). One hundred ninety-four eyes (89.0%) completed 1-year of follow-up. The centroid error in predicted residual astigmatism calculated using vector analysis was close to the origin in eyes with WTR astigmatism (0.17 diopter [D] @ 174.9 ± 0.54 D), while those with ATR and oblique astigmatism were significantly shifted toward the ATR direction (P < .001). The distance from the origin was significantly smaller in the WTR group than in ATR and oblique groups (P < .05). The centroid errors were shifted toward ATR in all toric IOL groups (P < .001); however, the distance from the origin was not different between groups (P = .52). Postoperatively, the mean absolute misalignment of the IOLs was 5.92 degrees ± 5.59 (SD) at 1 day and 6.24 ± 5.87 degrees at 1 year. The results of other clinical parameters were excellent, with no significant differences between astigmatism categories or IOL models.

CONCLUSION

Based on anterior corneal curvature alone, toric IOLs undercorrected ATR and oblique astigmatism; however, 1-year clinical results of toric IOLs were highly stable and satisfactory.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

Corneal astigmatism in cataract surgery patients from Bosnia and Herzegovina

PURPOSE

To determine corneal astigmatism prevalence, its correlations with age and symmetry pattern in fellow eyes of patients undergoing cataract surgery.

METHODS

This is a clinical-based retrospective cross-sectional study. Keratometry measurements of patients undergoing cataract surgery assigned to University Clinical Center Tuzla, Bosnia and Herzegovina, between January 2011 and June 2012 were recorded and analyzed retrospectively.

RESULTS

The study consisted of 4080 eyes of 2205 consecutive cataract surgery patients with a mean age of 68.24 years ± 9.25 (SD) (range 32-84 years), and 54.0% of the patients were women. Mean corneal astigmatism was 0.72 ± 0.61 D (range 0-6.5 D). The prevalence of corneal astigmatism 1.0 D or more was in 1291 eyes (31.64%), 1.5 D or more in 736 eyes (18.03%), 2.0 D or more in 396 eyes (9.71%) and 3.0 D or more in 108 eyes (2.65%). There was no significant difference in the magnitude of astigmatism between age groups (p = 0.10), male and female (p = 0.29) or right and left (p = 0.75) eyes. The prevalence and amount of astigmatism increased with age (p < 0.05). Gradual shift from with-the-rule astigmatism toward against-the-rule astigmatism was observed (p = 0.03). Patients with higher amount of astigmatism in one eye are more likely to have significant astigmatism in fellow eye (p < 0.01). Symmetry in pairs of eyes is present in eyes with astigmatism greater than 2.5 D (p < 0.01).

CONCLUSION

This study provides useful reference data for cataract surgeons and patients from Bosnia and Herzegovina.

Rotational Stability of Monofocal and Trifocal Intraocular Toric Lenses With Identical Design and Material but Different Surface Treatment

PURPOSE

To compare the rotational stability, total misalignment, and visual and refractive outcomes achieved with a trifocal toric versus a monofocal toric intraocular lens (IOL).

METHODS

In this prospective, interventional case series, eyes of patients consecutively scheduled for cataract surgery who had clinically relevant astigmatism were implanted with a FineVision Pod FT trifocal toric IOL or an Ankoris monofocal toric IOL (both PhysIOL SA, Liège, Belgium). Certain comorbidities, such as pseudoexfoliation syndrome, were allowed. IOL rotation and total misalignment were analyzed 15 minutes, 1 day, 1 week, 6 weeks, 6 months, and 1 year postoperatively.

RESULTS

Seventy-one eyes of 53 patients were assessed: 37 eyes were implanted with the trifocal IOL and 34 eyes with the monofocal IOL. More IOL rotation occurred in the monofocal group compared to the trifocal group (mean 4.23° ± 4.64° vs 2.55° ± 2.62°; P = .043, 12 months). Mean total misalignment was higher in the monofocal group (6.67° ± 6.59° at 12 months vs 3.79° ± 3.59° in the trifocal group) (P = .017). Postoperatively, more eyes achieved a refractive cylinder of 0.50 diopters or below in the trifocal group (65% at 12 months) than in the monofocal group, even in the monofocal subgroup analysis that excluded keratoconic eyes (42% at 12 months; P = .009).

CONCLUSIONS

The monofocal and trifocal toric IOLs both appear to effectively reduce refractive astigmatism and provide good visual acuity in astigmatic patients having cataract surgery. The trifocal toric IOL offers better rotational stability than the monofocal IOL, probably due to the higher frictional coefficient of its surface. [J Refract Surg. 2018;34(2):84-91.].

Comparing the Zeiss Callisto Eye and the Alcon Verion Image Guided System Toric Lens Alignment Technologies

PURPOSE

To compare the alignment meridian generated by the Zeiss Callisto Eye (Carl Zeiss AG, Dublin, CA) and the Alcon Verion Image Guided System (Alcon Laboratories, Inc., Fort Worth, TX).

METHODS

In this retrospective comparative evaluation of technology, intraoperative images were captured at different steps in the same surgery, allowing the comparison of the guidance lines generated by the Verion system to the parallel guidance lines generated by the Callisto Eye system. Measurements of each hemi-meridian were quantified using Adobe Photoshop 2015 CC software (Adobe Systems, San Jose, CA). The numbers of degrees separating these alignment meridians were calculated, entered into a database, and analyzed.

RESULTS

The authors found that of 98 captured images of 16 eyes, the two technologies were identical in 0 eyes (θ₁ = θ₂ = 0), similar by 3° in 52 (53%) captured images (θ₁ ≠ θ₂ ≠ 0), and different by at least 3° in 46 (47%) captured images (θ₁ ≠ θ₂ ≠ 0). The target meridians were superimposed, the target lines were minimally separated, and the target lines were dissimilar. It was noted that some intraoperative variation occurred from measurement to measurement. Within the small group of 16 cases of routine toric lens implantation in this study, the absolute average number of degrees of misalignment between the Verion and Callisto Eye systems was 3.355 for θ₁ and 3.838 for θ₂. On average, the intraoperative variation termed "drift" was noted to be 3.963° for θ₁, and 4.557° for θ₂.

CONCLUSIONS

The authors found that small deviations were frequent when comparing two sophisticated technologies. Although deviations greater than 3° occurred in less than 47% of captured images from 16 eyes, smaller but significant variations of less than 3° occurred in 53% of captured images from 16 eyes. It was rare to identify a large deviation. However, the authors identified "drift" in the same eye when measurements were taken at different times. The results indicate that the two systems are not currently interchangeable. Superiority of one system over the other was not determined. [J Refract Surg. 2017;33(7):482-487.].

Transitional conic toric intraocular lens for the management of corneal astigmatism in cataract surgery

Synopsis

Transitional toric intraocular lens (IOL) was developed to improve refractive outcomes in cataract surgery. We report refractive, vectorial outcomes, and stability of spherical equivalent over 12 months after implantation of this IOL.

Purpose

To evaluate visual and refractive outcomes of a transitional conic toric intraocular lens (IOL) (Precizon^®) for the correction of corneal astigmatism in patients undergoing cataract surgery.

Setting

The Ocular Microsurgery Institute (IMO), a private practice in Barcelona, Spain.

Design

This is a retrospective, non-randomized study.

Methods

Retrospective chart review of 156 patients with preoperative regular corneal astigmatism >0.75 diopters (D) who underwent consecutive phacoemulsification and Precizon toric IOL implantation between January 2014 and December 2015 was performed. Two groups were divided according to attempted residual refraction: group 1 with emmetropia and group 2 with mild myopia for monovision. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refraction were analyzed preoperatively and 3, 6, and 12 months postoperatively.

Results

Precizon toric IOL was implanted in 97 eyes of 61 patients. Six months postoperatively, none of the eyes lost any line of CDVA. In all, 98% of the eyes were within ±1.00 D of attempted spherical correction. The mean preoperative keratometric cylinder was 1.92 ± 1.04 D (range 0.75–6.78), and the mean postoperative refractive cylinder was 0.77 ± 0.50 D (range 0–2.25), with 81% of the eyes with ≤1.00 D of residual cylinder. Two IOLs required realignment due to intra-operative positioning error. Eleven eyes required enhancement with corneal refractive surgery.

Conclusion

Preexisting regular corneal astigmatism was effectively and safely corrected by the implantation of the transitional conic toric IOL in patients undergoing cataract surgery.