Accuracy of Toric Intraocular Lens Calculators with Predicted and Measured Posterior Corneal Astigmatism Across Different Types of Astigmatism

INTRODUCTION

This study is a retrospective case series to compare the accuracy of the Barrett toric calculator using predicted posterior corneal astigmatism (PCA) and PCA measurements using swept-source optical coherence tomography (SS-OCT) and a Scheimpflug camera. This evaluation was conducted across different types of anterior and posterior astigmatism.

METHODS

A total of 146 eyes from 146 patients implanted with toric intraocular lenses were included. Mean absolute prediction error, standard deviation of prediction error, and the percentage of eyes with prediction errors within ±0.50 diopters (D) were calculated using vector analysis. Biometric measurements were conducted using the IOLMaster 700 and Pentacam HR. A subgroup analysis was conducted based on the orientation of both anterior and posterior corneal astigmatism.

RESULTS

The Barrett toric calculator with predicted PCA yielded the best results, with 78.1% having a prediction error ≤ 0.50 D, which was a significantly higher percentage than the Barrett formula with the two versions of measured PCA (P < 0.05). In the subgroup with a horizontally steep meridian PCA using the IOLMaster 700, the Barrett formula with predicted PCA yielded the best results, with 78.3% of cases having a prediction error of less than 0.5 D. This percentage was significantly higher than the other two measured PCA subgroups (P < 0.05).

CONCLUSION

The Barrett toric formula with predicted PCA demonstrated a statistically significantly higher proportion of cases with a prediction error ≤ 0.5 D compared to the two measured PCA formulas (from the IOLMaster 700 or Pentacam). This trend persisted even when the posterior corneal astigmatism was horizontally steep.

Non-diffractive, toric, extended depth-of-focus intraocular lenses in eyes with low corneal astigmatism

BACKGROUND

To assess clinical outcomes after implanting toric, extended-depth-of-focus intraocular lenses (IOLs) to correct low corneal astigmatism in eyes with cataracts.

METHODS

47 eyes were implanted with the AcrySof IQ Vivity Toric DFT215 IOL. Main outcome measures were refractive error, monocular uncorrected and corrected distance (UDVA/CDVA), uncorrected and distance-corrected intermediate (UIVA/DCIVA), and uncorrected near and distance-corrected near (UNVA/DCNVA) visual acuities, monocular defocus curve, rotational stability, and IOLSAT and QUVID questionnaires. Patients were assessed at 3 months postsurgery.

RESULTS

All eyes had a postoperative spherical equivalent (SE) within ± 0.50 D and 97.87% (n = 46) had a refractive cylinder ≤ 0.50 D. The mean SE and refractive cylinder were - 0.10 ± 0.17 D and - 0.16 ± 0.24 D, respectively. The CDVA was ≥ 20/25 and ≥ 20/32 in 95.74% (n = 45) and 97.87% (n = 46) of eyes, respectively. The DCIVA was ≥ 20/32 in 85.11% (n = 40) of eyes and the DCNVA was ≥ 20/40 in 74.47% (n = 35). The mean values of CDVA, DCIVA, and DCNVA were - 0.02 ± 0.08, 0.14 ± 0.09, and 0.23 ± 0.12 logMAR, respectively. The defocus curve revealed good visual acuity at far and intermediate distances with a depth-of-focus of about 1.75 D. IOL rotation was 0.74 ± 1.13 degrees and all eyes had a rotation of less than 5 degrees. Patients reported either good or very good postoperative vision without eyeglasses under bright-light-conditions at distance (87.80%, 36/41) and intermediate distance (92.68%, 38/41). Between about 63.83%-72.34% (30-34) of patients reported no starburst, halos, or glare, or if experienced, were not bothersome.

CONCLUSIONS

The Vivity toric IOL implanted in eyes with low-astigmatism provides accurate refractive outcomes, good visual acuity at different distances and excellent rotational stability. Trial Registration The study was registered with the German Clinical Trials Register (DRKS00030579).

Rotational stability and clinical outcomes after implantation of a new monofocal toric intraocular lens with double C-loop design

PURPOSE

To investigate rotational stability and visual outcomes of patients unilaterally or bilaterally implanted with a new monofocal toric intraocular lens (IOL).

SETTING

Ophthalmology service, clinique Beausoleil, avenue de Lodève, Montpellier.

DESIGN

Single-center retrospective study.

METHODS

This study included patients who underwent routine cataract surgery with the PODEYE toric (BVI/PhysIOL SA, Liège, Belgium) IOL using the ZEISS CALLISTO eye®. Biometry and keratometry data, refractive outcomes, rotational stability, and astigmatism correction were recorded. IOL rotation was evaluated using an image analysis technique. Postoperative assessments were performed at 1 week, 1 month, and 4 to 6 months after surgery.

RESULTS

Clinical outcomes of 102 patients (136 eyes) were analyzed. Patients had a mean age of 74 years. Of the included eyes, 25% had an axial length greater than 24.5mm. Median postoperative IOL rotation from baseline (surgery) was 2̊. With the exception of one outlier (15̊ rotation), IOL rotation was ≤ 6̊ (1 month) and ≤ 10̊ (4-6 months) in 100% of the eyes. No surgical IOL re-positioning was required. Median postoperative corrected distance visual acuity was -0.08 logMAR, and median postoperative subjective cylinder was between 0.25 and 0.50 D.

CONCLUSION

The PODEYE toric IOL showed high rotational stability, allowing for correction of corneal astigmatism during cataract surgery.

Clinical Outcomes of Toric Intraocular Lenses in Patients with Fuchs Endothelial Corneal Dystrophy

INTRODUCTION

Implantation of toric intraocular lenses (IOLs) in patients with Fuchs endothelial corneal dystrophy (FECD) is still considered relatively contraindicated, without sufficient clinical evidence. Therefore, this study was designed to evaluate the results of toric IOL implantation in patients with FECD.

METHODS

A retrospective case-control study of 28 eyes of FECD patients and 84 eyes of healthy control patients who received toric IOLs during routine cataract surgery was performed. The outcome measures were uncorrected and corrected distance visual acuity, spherical equivalent, and refractive residual astigmatism.

RESULTS

The mean postoperative uncorrected and corrected distance visual acuity in the FECD eyes compared to the control eyes were 0.15 ± 0.14 vs. 0.13 ± 0.17, respectively (P = 0.32), and 0.05 ± 0.08 vs. 0.06 ± 0.10, respectively (P = 0.95). The spherical equivalent in the FECD eyes compared to the control eyes was - 0.29 ± 0.43 vs. - 0.21 ± 0.50, respectively (P = 0.19). The preoperative corneal centroid astigmatism in the FECD eyes compared to the control eyes was 0.85 D@93° ± 2.42° vs. 0.23 D@68° ± 2.50°, respectively (P = 0.43), and the mean preoperative corneal astigmatism magnitude was 2.26 ± 1.1 D vs. 2.28 ± 1.03 D, respectively (P = 0.82). A trend toward higher postoperative refractive centroid astigmatism was found in the FECD eyes compared with the control eyes: 0.24 D@28° ± 0.57° vs. 0.03 D@127° ± 0.53°, respectively (P = 0.09). However, the mean refractive astigmatism magnitude was similar in FECD eyes and the healthy control eyes: 0.52 ± 0.31 D vs. 0.42 ± 0.31 D, respectively (P = 0.44) (D diopters).

CONCLUSION

The postoperative refractive astigmatism (both centroid astigmatism and mean magnitude astigmatism) was no higher than 0.52 D in both groups. Therefore, FECD patients without corneal edema can be considered for toric IOLs.

Transitional conic toric intraocular lens evaluation after femtosecond laser-assisted cataract surgery using intraoperative aberrometry

PURPOSE

To assess refractive and visual outcomes following phacoemulsification with femtosecond laser-assisted cataract surgery (FLACS) using intraoperative aberrometry and implantation of a toric intraocular lens (IOL) in eyes with different degrees of astigmatism.

METHODS

One hundred two eyes of 70 patients who underwent implantation of the transitional toric 565 Precizon IOL (Ophtec BV) were enrolled. FLACS, capsular tension ring insertion, and intraoperative aberrometry were performed. Main outcome measures were refractive error, uncorrected- and corrected distance snellen decimal visual acuity values (UDVA and CDVA, respectively), and IOL rotation. Specifically, a vector analysis was carried out with J0 and J45 evaluation. Eyes were evaluated 1-year after surgery.

RESULTS

Overall, 94.12% (96 eyes) and 100% (102 eyes) of the eyes showed a spherical equivalent (SE) within ± 0.50D and ± 1.00D, respectively. The mean SE and refractive cylinder were - 0.06 ± 0.29D and - 0.23 ± 0.37D, respectively. Vector analysis revealed that 100% of the eyes were within ± 0.50D for the J0 and J45 cylindrical components. The mean toric axis rotation was 1.10 ± 1.71° (from 0° to 5°), 77% (79 eyes), and 100% (102 eyes) of the eyes showed UDVA and CDVA of 20/25, respectively. The postoperative mean values of monocular UDVA and CDVA were 0.88 ± 0.17 and 0.96 ± 0.07 (about 20/20), respectively. No patient required IOL realignment during the postoperative follow-up.

CONCLUSIONS

The present study suggests that the use of the Precizon IOL after FLACS, using intraoperative aberrometry in patients with different amounts of astigmatism, provides good visual acuity, accurate refractive outcomes, and excellent rotational stability.

The association of comfort and vision in soft toric contact lens wear

PURPOSE

This work set out to investigate if there was an association between subjective comfort and both subjective and measured vision during the use of contemporary daily disposable soft toric contact lenses.

METHODS

Thirty-eight habitual soft contact lens wearers wore each of three daily disposable toric lenses for one week in a prospective, crossover, randomised, single-masked study. The following clinical measures were recorded at dispensing and follow-up visits: biomicroscopy scores, lens fitting (including rotation and rotational stability), high and low contrast visual acuity, subjective vision quality and subjective ocular surface comfort. Subjective scores were collected using 0-10 numerical grading scales. Comfort scores were analysed using a linear regression model with age, sex, visit, phase of crossover ('phase'), lens type, lens rotation, lens rotational stability, visual acuity, cylinder power and subjective vision quality as factors of interest and then refined using backward stepwise regression.

RESULTS

Thirty six participants (31.1 ± 13.5 years) completed the study. Comfort scores were found to be associated with subjective vision quality (F = 127.0 ; p < 0.0001), phase (F = 7.2; p = 0.001) and lens type (F = 4.9; p = 0.009). Greater comfort scores were observed with greater subjective vision quality scores. Visual acuity was not statistically significant in the model.

CONCLUSION

This work suggests that symptoms of ocular discomfort may be more intense if there is also perceived visual compromise in daily disposable soft toric lenses. There was a stronger positive correlation between comfort and subjective vision quality compared with comfort and measured visual acuity.

Toric and mulitifocal lens utilization independent of patient cost and physician remuneration at a single institution

Purpose

To determine if the rates of toric and multifocal intraocular lenses (IOLs) are affected by patient cost or physician reimbursement.

Methods

At Naval Medical Center San Diego (NMCSD) there is no increased patient cost or physician reimbursement for toric or multifocal IOLs. The medical records of all patients who underwent cataract surgery with IOL implantation at NMCSD between 2013 and September 2016 were reviewed. The type of IOL implanted was identified. The rates of toric and multifocal IOL usage were compared to the rates reported in the 2016 American Society of Cataract and Refractive Surgery (ASCRS) Clinical Survey.

Results

The inclusion criterion was met for 2585 cataract surgeries. The percentage of toric IOLs at NMCSD in 2016 was 10%. If the patients that received 3 piece or anterior chamber IOLs were excluded, the percentage of single piece IOLs that were toric was 12%. The percentage of multifocal IOLs at NMCSD ranged from 0.8% in 2013 to 0.3% in 2016. The rates of toric and multifocal IOLs reported in the ASCRS clinical survey were 10% and 9%, respectively.

Conclusions and Importance

The rate of toric IOLs usage was not significantly affected by patient cost or physician reimbursement. The rate of multifocal IOLs usage was significantly lower at NMCSD.

Residual Refractive Astigmatism following Toric Intraocular Lens Implantation without Consideration of Posterior Corneal Astigmatism during Cataract Surgery with Low Anterior Keratometric Astigmatism upto 2.5 Dioptres

Purpose: To determine the refractive astigmatism following toric intraocular lens (tIOL) implantation without consideration of posterior keratometric astigmatism with a conventional tIOL calculator for eyes with low keratometric astigmatism (0.75D to 2.5D) and to theoretically compare the outcomes with predicted refractive astigmatism using a calculator with Barrett's formula.Methods: 34 eyes (34 patients) were assessed with Scheimpflug imaging and underwent tIOL implantation employing conventional tIOL calculator. Eyes were grouped on preoperative keratometric astigmatism as against-the-rule (ATR), with-the-rule (WTR), and oblique (OB). The refractive astigmatism was assessed at 1, 3, 6 and 12 months postoperatively and was classified as ATR, WTR, and OB. Theoretical refractive astigmatism calculations were performed for the same eyes using Barrett's formula.Results: Preoperatively keratometric astigamtism was ATR, WTR, and OB in 32%, 53% and 15% of eyes. At 12 months, in ATR, WTR and OB groups, 45.5%, 16.7% and 60% had ATR refractive astigmatism; 16.7%, 0%, and 20% had WTR refractive astigmatism; 55.6%, 54.5% and 20% were emmetropic (no sphere and cylinder) respectively. There was a significant difference between the theoretical predicted postoperative refractive astigmatism using conventional tIOL calculator and Barrett's formula (P < .05). Postoperative refractive astigmatism was not significantly different from the theoretical predicted refractive astigmatism with Barrett's formula but it was significantly higher than that with a conventional tIOL calculator.Conclusions: At 12 months, with a conventional tIOL calculator, postoperative emmetropia is achieved in half, two third and one-fifth of eyes with preoperatively ATR, WTR, and OB keratometric astigamtism respectively. Around 1/4^th WTR keratometric astigamtism eyes preoperatively were overcorrected to ATR refractive astigmatism whereas ½ATR remained undercorrected at 12 months Outcomes achieved were dissimilar to predicted outcomes with a conventional tIOL calculator but similar to those with Barrett's formula.

Reversal of Toric Intraocular Lens-corrected Corneal Astigmatism after Kahook Dual Blade Goniotomy

A 79-year-old man underwent phacoemulsification (phaco) with TORIC intraocular lens (IOL) insertion combined with Kahook dual blade (KDB) goniotomy of the right eye several months after a stand-alone phaco in the fellow eye. He had significant against-the-rule astigmatism in both eyes (2.41D @ 10° right, 2.40D @ 160° left) preoperatively. Postoperatively, nearly all corneal astigmatism disappeared in the right eye (0.60D @ 37°), while it remained the same in the left eye (2.00D @ 167°). Ophthalmologists should be aware that KDB may have an unreported effect of altering corneal astigmatism, which should be considered when inserting TORIC IOL.

HOW TO CITE THIS ARTICLE

Hirabayashi MT, McDaniel LM, et al. Reversal of Toric Intraocular Lens-corrected Corneal Astigmatism after Kahook Dual Blade Goniotomy. J Curr Glaucoma Pract 2019;13(1):42-44.

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.

Outcomes of toric supplementary intraocular lenses for residual astigmatic refractive error in pseudophakic eyes

PURPOSE

To evaluate rotational stability and visual and refractive outcomes of supplementary toric IOLs (Sulcoflex Toric 653T, Rayner Intraocular Lenses Ltd) for residual astigmatic refractive error in pseudophakic eyes.

METHODS

A retrospective interventional case series was conducted in a single surgeon practice. Charts of patients who had Sulcoflex Toric supplementary IOLs inserted between June 2009 and September 2015 were reviewed. Outcomes were compared between eyes with and without prior corneal transplant. Patients with at least 3-months follow-up were included.

RESULTS

In 51 eyes, mean UDVA improved from 20/86 to 20/43 (p = 0.002), though UDVA was better in eyes without corneal grafts (20/31) than eyes with (20/62). The proportion of eyes achieving 20/20 UDVA was 43%, 61% and 17% overall, in eyes with prior graft and in eyes with no prior graft, respectively. Sixty-four percentage achieved a spherical equivalent of within 0.5D of target (84% no graft, 34% prior graft). Fifty-three percentage of eyes achieved a cylinder of within 0.5D of target (no graft: 73%, prior graft: 0%). Mean lens rotation was 8.23° on day 1, and mean maximal rotation during follow-up was 17.63°. Sixty-two percentage of IOLs required repositioning. Of those that required repositioning, this was conducted a mean of 2.3 times. The mean final IOL rotation (following repositioning if required) was 6.17°.

CONCLUSION

Sulcoflex Toric supplementary IOLs result in good visual and refractive outcomes in eyes with no prior corneal graft. However, outcomes are sub-optimal in eyes with prior corneal transplantation, and the majority of lenses require repositioning.

Improving the Toric Intraocular Lens Calculation by Considering Posterior Corneal Astigmatism and Surgically-induced Corneal Astigmatism

PURPOSE

To investigate the effect of surgically induced corneal astigmatism (SICA) and total corneal astigmatism (TCA) estimation on the anterior corneal astigmatism (ACA)-based toric intraocular lens (IOL) calculation.

METHODS

Data from preoperative and postoperative corneal astigmatism, postoperative visual acuities, and refractive outcomes were collected. The incision was superior in with the rule anterior corneal astigmatism (WTRA) eyes and temporal in against the rule anterior corneal astigmatism eyes. The following five methods of calculating the toric IOL were compared: (1) ACA only and estimated SICA; (2) ACA with a fixed posterior corneal astigmatism (PCA) and estimated SICA; (3) ACA with a fixed PCA value and actual SICA; (4) and (5) TCA derived from the regression equations of ACA and actual SICA. The residual astigmatism was simulated. The Alpins method was used to analyze the astigmatism.

RESULTS

Sixty eyes from 46 patients were enrolled. Thirty eyes had WTRA and the other thirty had against the rule anterior corneal astigmatism. The vector and arithmetic means of the difference vector decreased when the information regarding the actual SICA and PCA was added to the calculation (from 0.59 diopters [D] @ 87.5° to 0.15 D @ 48.5°, and from 0.95 ± 0.53 to 0.71 ± 0.63 D, respectively; p < 0.001). The mean difference vector across the whole sample was lowest using model 5. The correction index was significantly closest to 1.0 in the WTRA group.

CONCLUSIONS

Researchers may improve the accuracy of post-implantation predictions by calculating toric IOL using exact SICA and TCA, with consideration of the PCA derived from the regression equation of ACA.

Combination of Toric and multifocal intraocular lens implantation in bilateral cataract patients with unilateral astigmatism

AIM

To assess the binocular visual function in bilateral cataract patients with unilateral astigmatism after combined implantations of Toric with multifocal intraocular lens (IOL), and to compare with that of Toric and monofocal IOL implantation.

METHODS

All the 30 patients with unilateral astigmatism suffered bilateral cataract were randomly divided into two groups: Toric plus multifocal IOL group and Toric plus monofocal IOL group. Uncorrected and corrected visual acuity at distance (5.0 m), intermediate distance (0.6 m), and near (0.33 m), contrast sensitivity, and stereopsis were assessed 6mo after surgery. Patients were also surveyed for visual disturbances and spectacle dependence.

RESULTS

Binocular uncorrected visual acuity (LogMAR) of Toric/multifocal IOL eyes at distance, intermediate, near were 0.05±0.05, 0.24±0.10, and 0.14±0.06 respectively. The values of Toric plus monofocal IOL eyes were 0.06±0.07, 0.26±0.08, and 0.37±0.10 respectively. These values did not indicate significant differences between two groups with exception of near visual acuity. In the photopic condition (with or without glare), the contrast sensitivity of multifocal IOL eyes was significant lower than the monofocal IOL eyes in 18 cpd. In the mesopic condition, the contrast sensitivity of multifocal group was significant lower than monofocal group in 12 cpd, and in mesopic glare condition, this significant difference was found both in 6 cpd and 12 cpd. The stereopsis of Toric/multifocal IOL eyes decreased slightly (100±80 seconds of arc, t=2.222, P=0.136). Mean near vision for patient satisfaction was statistically significantly higher in Toric/multifocal IOL group patients versus than that in Toric/monofocal IOL group (80% vs 25.5%, P=0.000). Visual disturbance was not noticed in either group.

CONCLUSION

Although the combination of Toric and multifocal IOL implantation results in compromising stereoacuity, it can still provide patients with high levels of spectacle freedom and good overall binocular visual acuity.

Demonstrating correction of low levels of astigmatism with realistic scenes

PURPOSE AND METHOD

Modern standard visual acuity tests are primarily designed as diagnostic tools for use during subjective refraction and normally bear little relation to real-world situations. We have developed a methodology to create realistic rendered scenes that demonstrate potential vision improvement in a relevant and engaging way. Low-cylindrical refractive error can be made more noticeable by optimizing the contrast and spatial frequencies, and by testing four different visual perception skills: motion tracking, pattern recognition, visual clutter differentiation and contrast sensitivity. Using a 1.00DC lens during iteration, we created a range of still and video scenes before optimizing to a selection 3-D rendered street scenes. These were assessed on everyday relevance, emotional and visual engagement and sensitivity to refractive correction for low-cylinder astigmats (0.75-1.00DC, n=74) wearing best spherical equivalent correction and then with astigmatism corrected.

RESULTS AND CONCLUSIONS

The most promising visual elements involved or combined optimized textures, distracting patterns behind text, faces at a distance, and oblique text. 91.9% of subjects (95% CI: 83.2, 97.0) reported an overall visual improvement when viewing the images with astigmatic correction, and 96% found the images helpful to determine which type of contact lens to use. Our method, which combines visual science with design thinking, takes a new approach to creating vision tests. The resultant test scenes can be used to improve patient interaction and help low cylinder astigmats see relevant, every-day benefits in correcting low levels (0.75 & 1.00DC) of astigmatism.

Evaluating the effect of splitting cylindrical power on improving patient tolerance to toric lens misalignment

PURPOSE

Evaluating the impact of splitting toric power on patient tolerance to misorientation such as with intraocular lens rotation.

SETTING

University vision clinic.

METHODS

Healthy, non astigmats had +1.50D astigmatism induced with spectacle lenses at 90°, 135°, 180° and +3.00D at 90°. Two correcting cylindrical lenses of the opposite sign and half the power each were subsequently added to the trial frame misaligned by 0°, 5° or 10° in a random order and misorientated from the initial axis in a clockwise direction by up to 15° in 5° steps. A second group of adapted astigmats with between 1.00 and 3.00DC had their astigmatism corrected with two toric spectacle lenses of half the power separated by 0°, 5° or 10° and misorientated from the initial axis in both directions by up to 15° in 5° steps. Distance, high contrast visual acuity was measured using a computerised test chart at each lens misalignment and misorientation.

RESULTS

Misorientation of the split toric lenses caused a statistically significant drop in visual acuity (F=70.341; p<0.001). Comparatively better acuities were observed around 180°, as anticipated (F=3.775; p=0.035). Misaligning the split toric power produced no benefit in visual acuity retention with axis misorientation when subjects had astigmatism induced with a low (F=2.190, p=0.129) or high cylinder (F=0.491, p=0.617) or in the adapted astigmats (F=0.120, p=0.887).

CONCLUSION

Misalignment of toric lens power split across the front and back lens surfaces had no beneficial effect on distance visual acuity, but also no negative effect.

Outcomes and possible risk factors associated with axis alignment and rotational stability after implantation of the Toric implantable collamer lens for high myopic astigmatism

AIM

To assess the visual outcomes and possible risk factors associated with axis alignment and rotational stability after implantation of Toric implantable collamer lens (TICL) for the correction of high myopic astigmatism.

METHODS

In this prospective, nonrandomized clinical study, 54 consecutive eyes of 29 patients with high myopic astigmatism received TICL implantation. To evaluate postoperative axis deviation from the intended axis, a digital anterior segment photograph was taken. The ultrasound biomicroscopy(UBM) was used to observe footplate-position.

RESULTS

After mean follow-up of 8.6 months, mean manifest refractive cylinder (MRC) decreased 79.3% from (-1.88±1.49)D preoperatively to (0.39±0.61)D postoperatively. MRC within 1.00 D occurred in 68.5% (37/54) of eyes, whereas 48.1% (26/54) had MRC within 0.50 D. Mean manifest refraction spherical equivalent (MRSE) changed from (-12.08±4.22)D preoperatively to (-0.41±0.61)D postoperatively. Uncorrected binocular vision of 20/20 or better occurred in 72.2% (39/54) of patients compared with binocular best-corrected visual acuity (BCVA) of 20/20 or better in 44.4% (24/54) preoperatively. The mean difference between intended and achieved TICL axes was (6.96±8.37)°. Footplates of TICLs were in the ciliary sulcus in 22 eyes (46.3%), below the ciliary sulcus in 32 eyes (53.7%). The angle of TICL rotation had significant correlation with the footplates-position (t=2.127; P=0.045) and the postoperative TICL vaulting (r=-0.516; P=0.000).

CONCLUSION

The results of our study further support the safety, efficacy and predictability of TICL for the correct high myopic astigmatism. The footplate-position of TICL and vault value should be taken into consideration as two possible risks factors for TICL rotation.