Randomized controlled clinical trial to evaluate different intraocular lenses for the surgical compensation of low to moderate-to-high regular corneal astigmatism during cataract surgery

Rotational stability of toric intraocular lenses by lens model and haptic design: systematic review and single-arm meta-analysis

Rotational stability is key for optimizing postoperative visual outcomes because even a small degree of rotation of a toric intraocular lens (IOL) from its target axis can result in a significant reduction in astigmatic correction. This systematic review and meta-analysis evaluated the rotational stability of toric IOLs of different lens models and haptic designs. All published studies and clinical trials that investigate postoperative rotation of toric IOLs were searched and evaluated. Quality of studies was assessed using the Methodological Index for Nonrandomized Studies scale. A single-arm meta-analysis was performed in R4.3.1 software with subgroup analysis performed based on lens model and haptic design. 51 published studies of 4863 eyes were included in the meta-analysis. The pooled mean absolute rotation of all toric IOLs was 2.36 degrees (95% CI, 2.08-2.64). Postoperative rotation is dependent on many aspects of lens material and design. Modern commercially available toric IOLs exhibit exceptional rotational stability.

Toric Monofocal Intraocular Lenses for the Correction of Astigmatism during Cataract Surgery: A Report by the American Academy of Ophthalmology

PURPOSE

To review the published literature evaluating the visual and refractive outcomes and rotational stability of eyes implanted with toric monofocal intraocular lenses (IOLs) for the correction of keratometric astigmatism during cataract surgery and to compare those outcomes with outcomes of eyes implanted with nontoric monofocal IOLs and other astigmatism management methods performed during cataract surgery. This assessment was restricted to the toric IOLs available in the United States.

METHODS

A literature search of English-language publications in the PubMed database was last conducted in July 2022. The search identified 906 potentially relevant citations, and after review of the abstracts, 63 were selected for full-text review. Twenty-one studies ultimately were determined to be relevant to the assessment criteria and were selected for inclusion. The panel methodologist assigned each a level of evidence rating; 12 studies were rated level I and 9 studies were rated level II.

RESULTS

Eyes implanted with toric IOLs showed excellent postoperative uncorrected distance visual acuity (UCDVA), reduction of postoperative refractive astigmatism, and good rotational stability. Uncorrected distance visual acuity was better and postoperative cylinder was lower with toric IOLs, regardless of manufacturer, when compared with nontoric monofocal IOLs. Correcting pre-existing astigmatism with toric IOLs was more effective and predictable than using corneal relaxing incisions (CRIs), especially in the presence of higher magnitudes of astigmatism.

CONCLUSIONS

Toric monofocal IOLs are effective in neutralizing pre-existing corneal astigmatism at the time of cataract surgery and result in better UCDVA and significant reductions in postoperative refractive astigmatism compared with nontoric monofocal IOLs. Toric IOLs result in better astigmatic correction than CRIs, particularly at high magnitudes of astigmatism.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Repositioning Rates of Toric IOLs Implanted in Cataract Surgery Patients: A Retrospective Chart Review

Purpose

To determine the incidence of postoperative repositioning of toric intraocular lenses (IOLs) due to clinically significant rotation.

Patients and Methods

This study included consecutive cataract patients with pre-existing astigmatism who had undergone cataract surgery with toric IOL implantation by a single experienced surgeon. Case records of patients who were recommended to undergo toric IOL repositioning surgery due to clinically significant postoperative IOL rotation from the implanted axis were identified. The need for a secondary intervention to manage residual astigmatism was based upon postoperative residual astigmatic error ≥0.75 D, the patient's qualitative dissatisfaction with the level of postoperative distance vision, dilated post-op examination, and confirmation of the significant potential for astigmatism reduction.

Results

Case records of 993 eyes implanted with AcrySof toric (N = 362), Tecnis Toric I (N = 53), Tecnis Toric II (N = 308), or enVista Toric IOLs (N = 270) were included. Postoperative toric IOL repositioning was recommended in 16 eyes (1.6%). The repositioning rate was highest in the eyes implanted with Tecnis Toric I (5.7%), followed by AcrySof Toric (2.2%), enVista Toric IOLs (1.1%), and Tecnis Toric II (0.6%).

Conclusion

This real-world analysis of eyes implanted with toric IOLs revealed that the rate of surgical IOL repositioning due to clinically significant IOL rotation was lower than 2% for enVista and Tecnis Toric II IOLs. When needed and with appropriate planning, toric IOL repositioning can be very successful.

Comparison of Visual Outcomes Between Toric Intraocular Lenses and Clear Corneal Incisions to Correct Astigmatism in Image–Guided Cataract Surgery

Purpose

To compare the astigmatism correction effects of toric intraocular lenses (IOL) and clear corneal incisions during image-guided cataract surgery.

Methods

All patients with regular corneal astigmatism of 0.75–1.5 D underwent cataract surgery and astigmatism correction using the Callisto eye image-guided system. One group had implantation of an AcrySof toric IOL. Another group had implantation of aspheric IOL with 3.0 mm single clear corneal incision (SCCI) on the steep axis. Uncorrected and best-corrected spectacle visual acuity, refraction, and toric IOL axis were evaluated at 1, 4, and 12 weeks postoperatively.

Results

Sixty-eight eyes of 68 patients were included. The mean residual refractive cylinder was 0.34 ± 0.40 D in the toric group and 0.64 ± 0.57 D in the SCCI group. There were no significant differences in residual refractive cylinder, spherical equivalent, uncorrected distance visual acuity (UDVA), and best-corrected spectacle visual acuity (BCSVA) between groups. The percentage of the residual cylinder within ± 0.50 D was 75 and 56% for toric and SCCI cases, respectively (p > 0.1). The mean surgical induced astigmatism vector was 0.61 ± 0.29 D in the SCCI group and 1.04 ± 0.38 D in the toric group. The mean magnitude of error was negative (−0.54 ± 0.48 D) and the correction index was <1.0 (p < 0.05) in SCCI group. At 3 months, all toric IOL alignment errors were within 5 degrees from the intended axis.

Conclusions

Both toric IOL and SCCI can correct low and medium astigmatism effectively with the help of a precise image-guided system.

Comparing IOLM700 TK, Berdahl and Hardten astigmatism fix calculator and Barrett Rx formula in managing residual astigmatism due to toric intraocular lens misalignment

Purpose:

To compare the accuracy in astigmatism reduction by using IOLM 700 steep total keratometry (TK) axis, Berdahl and Hardten astigmatism fix, and Barrett Rx formula following misaligned toric intraocular lens (IOL).

Methods:

Ten patients with residual refractive astigmatism due to misalignment following toric IOL implantation were included in this retrospective study. They were analyzed at days 4, 7/8, and 10/11 following primary cataract surgery on the platform of Berdahl and Hardten astigmatism fix, Barrett Rx formula, and IOLM 700 to determine the optimum axis of repositioning, and underwent IOL realignment on the steep TK axis of IOLM 700 assisted by the Callisto eye. The final outcome parameters were subjective refraction and orientation of toric IOL assessed 22 ± 1 days following repositioning surgery. These parameters were fed in the Barrett Rx formula and its vector analysis graph was utilized to determine the predicted ideal axis with the least residual astigmatism and the estimated residual astigmatism if the toric IOL was realigned according to the axis suggested by Berdahl and Hardten astigmatism fix and Barrett Rx formula.

Results:

Realigning the toric IOL on IOLM 700 steep TK axis along with the Callisto eye reduces the residual refractive astigmatism significantly (P = 0.003) from 2.00 ± 0.78 D to 0.18 ± 0.12 D (90.5 ± 7.6%) in comparison to the estimated 0.57 ± 0.31 D (68.4 ± 21.9%) by Berdahl and Hardten astigmatism fix and 0.61 ± 0.33 D (66.4 ± 23.5%) by Barrett Rx formula.

Conclusion:

Realigning the misaligned toric IOL on the IOLM 700 steep TK axis gives a better reduction in the residual refractive astigmatism in comparison to Berdahl and Hardten astigmatism fix and Barrett Rx formula.

Time-efficiency assessment of guided toric IOL cataract surgery: a pilot study

PURPOSE

To compare the time spent on toric intraocular lens (IOL) implantation during cataract surgery using a manual-marking versus a digital image-guided system (the Verion) for toric IOL alignment.

SETTINGS

All procedures were performed at the Instituto Oftalmológico Quirónsalud ophthalmology clinic (A Coruña, Spain).

DESIGN

We designed an experimental and longitudinal (1-month follow-up) study.

METHODS

A total of 98 eyes of 65 participants (68.2 ± 12.2 years) were divided into two groups: 49 eyes operated with toric IOL alignment using a manual-marking technique (manual group) and another 49 eyes operated using image-guided marking (Verion group). The primary variable for comparison between both groups was cataract surgery time. Other outcomes such as toric IOL misalignment, spherical equivalent (SE), astigmatism, uncorrected distance visual acuity (UDVA), and corrected distance visual acuity (CDVA) were also measured.

RESULTS

The total cataract surgery time was 2:09 minutes shorter (p  < 0.001) with the Verion system (12:12 ± 2:20) compared to the surgical procedure performed using manual marking (15:27 ± 3:04). One month after surgery, there were no statistical differences in terms of toric IOL misalignment between the Verion (3.38° ± 2.95°) and the manual group (4.66° ± 3.95°). No statistical differences were observed between groups for refractive and visual outcomes either (p ≥ 0.05).

CONCLUSIONS

The cataract surgery time was reduced when the procedure was assisted using the Verion system to align the IOL compared to manual marking, maintaining the same efficacy in terms of toric IOL misalignment, residual refraction, and visual acuity.

Effect of defocus combined with rotation on the optical performance of trifocal toric IOLs

PURPOSE

To objectively analyze the optical quality of the FineVision Toric intraocular lens (IOL) with two cylinder powers when different combinations of rotations and residual refractive errors are induced.

METHODS

This study assessed the FineVision Toric IOL with two different cylinder powers: 1.5 and 3.0 diopters (D). Three different rotation positions were considered: centered, 5° and 10° rotated. An optical bench (PMTF) was used for optical analysis. The optical quality of the IOLs was calculated by the modulation transfer function (MTF) at five different focal points (0.0, 0.25, 0.50, 0.75, and 1.00 D).

RESULTS

The MTF averaged value of the reference situation was 38.58 and 37.74 for 1.5 and 3.0 D of cylinder, respectively. For the 1.5 D cylinder, the combination of 5° of rotation with a defocus of 0.25, 0.50, 0.75, and 1.0 D induced a decrease on the MTF of 12.39, 19.94, 23.43, 24.23 units, respectively. When induced rotation was 10°, the MTF decrease was 17.26, 23.40, 24.33, 24.48 units, respectively. For the 3.0 D cylinder, the combination of 5° with 0.25, 0.50, 0.75, and 1.0 D of defocus, induced a decrease on the MTF of 12.51, 18.97, 22.36, 22.48 units, respectively. When induced rotation was 10°, the MTF decrease was: 18.42, 21.57, 23.08, and 23.61 units, respectively.

CONCLUSION

For both FineVision Toric IOLs there is a certain optical tolerance to rotations up to 5° or residual refractive errors up to 0.25 D. Situations over these limits and their combination would affect the visual quality of patients implanted with these trifocal toric IOLs.

Femtosecond laser-assisted arcuate keratotomy at the time of cataract surgery for the management of preexisting astigmatism

PURPOSE

To evaluate the outcomes of femtosecond laser-assisted arcuate keratotomy combined with cataract surgery in eyes with low-to-moderate corneal astigmatism.

SETTING

Eyes of York Private Practice Ophthalmology Clinic, York, Pennsylvania, USA.

DESIGN

Retrospective case series.

METHODS

This retrospective analysis included case records of patients with preexisting corneal astigmatism ranging from 0.5 to 2.0 diopter (D). Study parameters included corneal astigmatism, refractive astigmatism, and uncorrected (UDVA) and corrected (CDVA) distance visual acuities. The results, which were analyzed at 3 months postoperatively, included frequency distribution histograms, vector analysis, and single-angle polar plots.

RESULTS

The study comprised case records of 189 eyes of 143 patients (56 men and 87 women). The postoperative refractive astigmatism was reduced significantly compared with preoperative corneal astigmatism to 0.14 D ± 0.23 (SD) from 0.92 ± 0.34 D (P < .001). One hundred eighty-one eyes (95.8%) demonstrated postoperative refractive astigmatism of 0.5 D or less. The mean surgically induced change along the preoperative steep axis was -0.59 ± 0.56 D, and the change along the orthogonal axis was 0.01 ± 0.35 D. Postoperatively, 171 eyes (90.5%) had astigmatism angle of error of 15 degrees or less. The postoperative mean UDVA and CDVA were 0.09 ± 0.16 logarithm of the minimum angle of resolution (logMAR) and 0.02 ± 0.05 logMAR, respectively. One hundred seventy eyes (90%) had a postoperative UDVA of 20/30 or better. The results demonstrated stability at 12 months postoperatively. No intraoperative or postoperative arcuate keratotomy-related events were observed.

CONCLUSION

The results suggest that femtosecond laser-assisted arcuate keratotomy represents a safe and effective method for astigmatism correction at the time of cataract surgery with demonstrated stability of correction for at least 1 year postoperatively.

[Correction of corneal astigmatism in femtosecond laser-assisted cataract extraction surgery]

PURPOSE

To perform a comparative analysis of clinical and functional results and efficiency of corneal astigmatism correction after femtosecond laser-assisted cataract surgery (FLACS) with implantation of toric intraocular lens (TIOL) and in combination with arcuate keratotomy (FL-AC).

MATERIAL AND METHODS

The examination included 60 patients (60 eyes). The first group consisted of 30 patients (30 eyes) who underwent FLACS with implantation of TIOL (Acrysof IQ Toric, Alcon, U.S.A.); the second group consisted of 30 patients (30 eyes) who underwent FLACS in combination with FL-AC. The examination was carried out before the operation, on the 3^rd day and 3 months after surgery. Corneal astigmatism correction efficiency was analyzed using the Alpins method and graphical vector analysis.

RESULTS

Uncorrected visual acuity (UCVA) indices increased to 0.70±0.24 and 0.66±0.31 in the FLACS with TIOL and FLACS with FL-AC groups, respectively, without statistically significant differences between the groups (p=0.03). The value of the residual cylinder was significantly lower in the FLACS with TIOL group (-0.77±0.58 and -0.80±0.39) compared with FLACS with FL-AC (-1.08±0.81 and -1.18±0.63) both on day 3 (p=0.02), and 3 months after surgery (p=0.02). In the FLACS with TIOL group, a higher correction index (0.99±0.18) and a smaller difference vector (0.77±0.64) were achieved compared to the FLACS with FL-AC group (0.78±0.35 and 1.05±0.76, respectively). Corneal higher-order aberrations (HOA) significantly differed on the 3^rd day after surgery in the 3.0 mm (p=0.04) and 5.0 mm (p=0.04) zones between the groups. Endothelial cells density was 2460.50±328.40 and 2526.125±196.74 cl/mm² after 3 months of observation in the FLACS with TIOL and FLACS with FL-AC groups, respectively (p=0.61).

CONCLUSION

Both methods had comparable visual acuity results (p=0.03). FLACS with TIOL provided more effective correction of the cylindrical component of refraction to 3.0 D.

Optical tolerance to rotation of trifocal toric intraocular lenses as a function of the cylinder power

BACKGROUND

The aim was to assess the impact of 5- and 10-degree rotations in the optical quality of a trifocal toric intraocular lens with different amounts of cylinder.

METHODS

Two Physiol Toric intraocular lenses with 1.5 and 3.0 D of cylinder were analysed in three different positions: centred, 5 and 10 degrees rotated. The optical quality of the intraocular lenses was evaluated with the PMTF optical bench through specific perpendicular targets. The analysis was performed by the through-focus modulation transfer function curves and the modulation transfer function corresponding to distance vision (0 D of vergence).

RESULTS

For a centred situation, the through-focus modulation transfer function curves of both intraocular lenses showed the classical three peaks corresponding to the powers of the two principal meridians of the intraocular lenses. When 5 and 10 degrees of rotation were induced, the three peaks were attenuated in both cases. The case with the intraocular lens with 3.0 D of cylinder and 10 degrees of rotation showed the worst optical quality and a significant loss of trifocality. The modulation transfer function values obtained for distance vision also showed the worst optical quality for the intraocular lens with 3.0 D of cylinder and 10 degrees of rotation.

CONCLUSION

Rotations over 5 degrees decreased the optical quality of trifocal toric intraocular lenses, being this reduction moderate from 5 to 10 degrees for low levels of cylinder (≤1.5 D). For mid-high levels of cylinder (≥3.0 D), rotations over 5 degrees cause a significant loss of optical quality at all object distances.

Efficacy of astigmatic correction after femtosecond laser-guided cataract surgery using intraoperative aberrometry in eyes with low-to-moderate levels of corneal astigmatism

PURPOSE

To evaluate the efficacy of astigmatic correction with two types of toric intraocular lenses (IOLs) after femtosecond laser-assisted cataract surgery (FLACS) in eyes with low-to-moderate corneal astigmatism using intraoperative aberrometry for optimizing the position of the toric IOL.

METHODS

Retrospective study includes a total of 99 eyes of 73 patients with anterior keratomeric astigmatism ≤ 3 D and undergoing FLACS (Catalys, Johnson & Johnson Vision) with implantation of a monofocal (Ankoris, PhysIOL) or a multifocal toric IOL with the same platform (Pod FT, PhysIOL). In all cases, intraoperative aberrometry was used (Optiwave refractive analysis, ORA, system, Alcon). Visual and refractive outcomes were evaluated preoperatively and at 4 months after surgery with vector analysis of astigmatic changes.

RESULTS

A total of 89.9%, 93.9% and 97.0% showed a postoperative sphere, cylinder and spherical equivalent within ± 0.50 D, respectively. Mean difference vector (DV) was 0.22 ± 0.27 D, mean magnitude of error (ME) was 0.13 ± 0.29 D, and mean angle of error (AE) was 1.52 ± 11.64°. Poor correlations of preoperative corneal astigmatism with DV (r = - 0.032, p = 0.833), ME (r = - 0.344, p = 0.001) and AE (r = - 0.094, p = 0.377) were found. Likewise, no statistically significant differences were found between monofocal and multifocal toric IOL subgroups in DV (p = 0.580), ME (p = 0.702) and AE (p = 0.499).

CONCLUSIONS

The combination of FLACS and intraoperative aberrometry to optimize the position of a toric IOL allows a very efficacious correction of preexisting low-to-moderate corneal astigmatism.

Changes in corneal astigmatism during 20 years after cataract surgery

PURPOSE

To examine how corneal astigmatism changes with age over 20 years after cataract surgery and to assess whether the changes differ from those in eyes that did not have surgery.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

DESIGN

Retrospective case study.

METHODS

Using an autokeratometer, corneal astigmatism was measured preoperatively, at baseline (the day the surgically induced astigmatism stabilized), and 10 years and 20 years after baseline. The change in corneal astigmatism between baseline and 10 years, 10 years and 20 years, and baseline and 20 years was determined using power vector analysis and compared between the time intervals and between groups.

RESULTS

The study assessed 74 eyes that had phacoemulsification with a horizontal scleral incision more than 21 years ago (surgery group) and 68 eyes that did not have surgery (no-surgery group). The mean vertical/horizontal change in corneal astigmatism (J0) between baseline and 20 years was -0.64 diopter (D) in the surgery group and -0.49 D in the no-surgery group. The oblique change (J45) was -0.03 D in the surgery group and 0.07 D in the no-surgery group. Using multivariate comparison, the mean J0 and J45 values were not significantly different between baseline and 10 years or between 10 years and 20 years in both groups (P ≥ .2350). The J0 and J45 values were not significantly different between the 2 groups at any time interval (P ≥ .1331).

CONCLUSIONS

Corneal astigmatism continues to change toward against-the-rule astigmatism over 20 years after cataract surgery. This change was similar in eyes that did not have surgery.

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

PURPOSE

To compare the outcomes of the combination of an image-guided system and intraoperative aberrometer with the surgeon's standard of care in correcting astigmatism using toric intraocular lenses (IOLs) or corneal incisions.

SETTING

Single site in United States.

DESIGN

Prospective case series.

METHODS

Contralateral eyes of patients having uncomplicated bilateral cataract surgery and astigmatism correction were randomly assigned to Group A or Group B. Group A received the surgeon's preferred standard of care. Group B had preoperative planning using an image-guidance system (VERION), intraoperative aberrometry (ORA System with VerifEye+), and femtosecond laser-assisted cataract surgery. The primary endpoint was the residual refractive astigmatism at 3 months.

RESULTS

Thirty-eight eyes were treated with toric IOLs and 40 eyes with corneal astigmatic incisions. On average, toric IOLs resulted in almost 0.25 diopter (D) less cylinder than corneal astigmatic incisions (P < .01), with no difference between groups (P = .41). There was no statistically significant difference in the mean spherical equivalent refraction by group (P = .51). At 3 months, the IOL in 4 eyes (11%) (2 in Group A and Group B each) was more than 10 degrees of absolute orientation from the intended orientation. The mean keratometry was 0.16 D higher with the image-guided system compared with optical biometry (Lenstar). The vector difference between the 2 measurements was 0.5 D or lower in all eyes.

CONCLUSIONS

The combined use of an image-guided system and intraoperative aberrometer did not significantly improve outcomes compared with the surgeon's standard of care. Based on keratometry, there was good agreement in corneal astigmatism measurements between the image-guided system and the optical biometer.

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.

Comparison of Two Toric IOL Calculation Methods

PURPOSE

To compare two calculators for toric intraocular lens (IOL) calculation and to evaluate the prediction of refractive outcome.

METHODS

Sixty-four eyes of forty-five patients underwent cataract surgery followed by implantation of a toric intraocular lens (Zeiss Torbi 709 M) calculated by a standard industry calculator using front keratometry values. Prediction error, median absolute error, and refractive astigmatism error were evaluated for the standard calculator. The predicted postoperative refraction and toric lens power values were evaluated and compared after postoperative recalculation using the Barrett calculator.

RESULTS

We observed a significant undercorrection in the spherical equivalent (0.19 D) by using a standard calculator (p ≤ 0.05). According to the Baylor nomogram and the refractive influence of posterior corneal astigmatism (PCA), undercorrection of the cylinder was lower for patients with WTR astigmatism, because of the tendency of overcorrection. An advantage of less residual postoperative SE, sphere, and cylinder for the Barrett calculator was observed when retrospectively comparing the calculated predicted postoperative refraction between calculators (p ≤ 0.01).

CONCLUSION

Consideration of only corneal front keratometric values for toric lens calculation may lead to postoperative undercorrection of astigmatism. The prediction of postoperative refractive outcome can be improved by using appropriate methods of adjustment in order to take PCA into account.

Toric intraocular lens orientation and residual refractive astigmatism: an analysis

Purpose

To analyze intraocular lens (IOL) orientation data from an online toric back-calculator (astigmatismfix.com) for determining if differences were apparent by lens type.

Methods

A retrospective review of astigmatismfix.com toric back-calculations that included IOL identification and intended orientation axis.

Results

Of 12,812 total validated calculation records, 8,229 included intended orientation and lens identification data. Of the latter, 5,674 calculations (69%) involved lenses oriented 5° or more from their intended position. Using estimated toric lens usage data, the percentage of lenses with orientation ≥5° from intended was 0.89% overall, but the percentage varied significantly between specific toric lens brands (P<0.05). The percentage of back-calculations related to lenses that were not oriented as intended was also statistically significantly different by lens brand (P<0.05). When IOLs were misoriented, they were significantly more likely to be misoriented in a counterclockwise direction (P<0.05). This was found to be due to a bias toward counterclockwise orientation observed with one specific brand, a bias that was not observed with the other three brands analyzed here.

Conclusion

The percentage of eyes with lens orientation ≥5° from intended in the Toric Results Analyzer data set was <1% of toric IOLs in general, with the relative percentage of Tecnis^® Toric IOLs significantly higher than AcrySof^® Toric IOLs. Both of these had higher rates than the Staar^® Toric and Trulign^® Toric lenses, with the availability of higher Tecnis and AcrySof cylinder powers a likely contributing factor. The AcrySof Toric IOL appears to be less likely than the Tecnis Toric IOL to cause residual astigmatism as a result of misorientation. The Tecnis Toric IOL appears more likely to be misoriented in a counterclockwise direction; no such bias was observed with the AcrySof Toric, the Trulign^® Toric, or the Staar Toric IOLs.

Visual Performance after Bilateral Implantation of a Four-Haptic Diffractive Toric Multifocal Intraocular Lens in High Myopes

Background. The vision with diffractive toric multifocal intraocular lenses after cataract surgery in long eyes has not been studied previously. Objectives. To report visual performance after bilateral implantation of a diffractive toric multifocal intraocular lens in high myopes. Methods. Prospective, observational case series to include patients with axial length of ≥26 mm and corneal astigmatism of >1 dioptre who underwent bilateral AT LISA 909M implantation. Postoperative examinations included photopic and mesopic distance, intermediate, and near visual acuity; photopic contrast sensitivity; visual symptoms (0–5); satisfaction (1–5); and spectacle independence rate. Results. Twenty-eight eyes (14 patients) were included. Postoperatively, mean photopic monocular uncorrected distance, intermediate, and near visual acuities (logMAR) were 0.12 ± 0.20 (standard deviation), 0.24 ± 0.16, and 0.29 ± 0.21, respectively. Corresponding binocular values were −0.01 ± 0.14, 0.13 ± 0.12, and 0.20 ± 0.19, respectively. One eye (4%) had one-line loss in vision. Under mesopic condition, intermediate vision and near vision decreased significantly (all P ≤ 0.001). Contrast sensitivity at all spatial frequencies did not improve significantly under binocular condition (all P > 0.05). Median scores for halos, night glare, starbursts, and satisfaction were 0.50, 0.00, 0.00, and 4.25, respectively. Ten patients (71%) reported complete spectacle independence. Conclusions. Bilateral implantation of the intraocular lens in high myopes appeared to be safe and achieved good visual performance and high satisfaction.