Limbal relaxing incisions with cataract surgery

Modified femtosecond laser-assisted arcuate keratotomy for managing low corneal astigmatism using trifocal intraocular lens implantation in Chinese cataract patients

To evaluate the visual outcome and astigmatic correction following trifocal intraocular lens (IOL) implantation using the modified femtosecond laser-assisted arcuate keratotomy (FSAK) in Chinese cataract patients with low astigmatism. This retrospective study included consecutive cataract patients with regular corneal astigmatism ranging from 0.75 to 1.5 D who underwent FSAK combined with the trifocal IOL implantation between November 2020 and September 2022. Monocular uncorrected distance visual acuity, uncorrected intermediate visual acuity, uncorrected near visual acuity, and refractive data were collected at the 3-month follow-up. The pre- and post-operative high-order aberrations (HOAs) were recorded. The variation in astigmatism was analyzed using Alpins vector analysis. A total of 27 eyes from 23 patients were analyzed. The monocular uncorrected distance visual acuity (UDVA) (5 m) at the 3-month follow-up was 0.04 ± 0.09 logarithm of the minimum angle of resolution (logMAR), which was significantly improved compared with the preoperative value of 0.95 ± 0.51 logMAR (P <.001). The corneal astigmatism was significantly reduced from 1.24 ± 0.42 D to 0.49 ± 0.34 D (P <.001). The target-induced astigmatism (TIA) was 1.25 ± 0.43 D, the surgically induced astigmatism (SIA) was 1.16 ± 0.52 D, and the difference vector (DV) was 0.5 ± 0.34 D. The magnitude of error (ME) (difference between SIA and TIA) was -0.1 ± 0.41 D, and the correction index (CI) (ratio of SIA to TIA) was 0.93 ± 0.36. The angle of error was 3.92° ± 16.90°. Total HOA was reduced from 0.89 ± 1.11 to 0.41 ± 0.55 (P = 0.184), and the corneal HOA was lowered from 0.17 ± 0.18 to 0.10 ± 0.10 (P = 0.129). Implantation of trifocal IOL following the modified FSAK in Chinese cataract patients exhibited excellent visual efficacy and effectively reduced corneal astigmatism.

Refractive outcomes following bilateral implantation of a diffractive toric intraocular lens in a multisurgeon hospital setting

OBJECTIVE

To assess residual postoperative refractive astigmatism following bilateral implantation of a trifocal toric intraocular lens (IOL) in a real-world multisurgeon setting.

DESIGN

Prospective multisurgeon study (6 surgeons at 2 sites).

METHODS

Bilateral implantation of a trifocal toric IOL (AcrySof PanOptix IOL; Alcon Vision LLC, Fort Worth, TX, USA) was performed in 140 eyes of 70 patients. Patients were assessed on day 1 and 3 months postoperatively. The primary outcome measure was residual astigmatism. Secondary endpoints included absolute prediction error, IOL rotation, binocular uncorrected and distance-corrected visual acuities at near (40 cm), intermediate (60 cm), and distance (6 m) and spectacle independence evaluated with the validated Intraocular Lens Satisfaction questionnaire.

RESULTS

Mean preoperative cylinder was 1.25 ± 0.72 D and was 0.39 ± 0.28 D at 3 months postoperatively. At 3 months postoperatively, mean residual astigmatism was 0.39 ± 0.28 D (range, 0-1.25 D), and 118 eyes (84.3%) had postoperative astigmatism of 0.5 D or less. Mean absolute prediction error was 0.25 ± 0.21 D (range, 0-1.13 D), and 124 eyes (88.6%) had absolute prediction error of 0.5 D or less. At 3 months postoperatively, mean absolute rotation was 2.0 ± 2.7 degrees compared with baseline (range, 0-15 degrees), and 133 IOLs (95.0%) were within 5 degrees of the implanted axis. Additionally, 55 patients (79%) reported never or rarely using spectacles at near, 66 (94%) at intermediate, and 67 (96%) at distance.

CONCLUSIONS

The results of this study demonstrate that implantation with the PanOptix toric IOL can provide excellent refractive and visual outcomes with minimal residual astigmatism.

Outcomes of peripheral corneal relaxing incisions for residual astigmatism in patients after cataract surgery

PURPOSE

To evaluate the outcomes of peripheral corneal relaxing incisions (PCRIs) for correcting residual astigmatism in eyes after cataract surgery.

SETTING

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

DESIGN

Retrospective case series.

METHODS

Retrospectively, we reviewed all consecutive cases that had previous cataract surgery and subsequent PCRIs by 1 surgeon. The PCRI length was determined according to a nomogram based on age and manifest refractive astigmatism. Visual acuity and manifest refractive astigmatism before and after the PCRIs were compared. Vector analysis was performed, and net refractive changes along the incision meridian were calculated.

RESULTS

Criteria were met by 111 eyes. After the PCRIs, mean uncorrected visual acuity was significantly improved, and the percentage of eyes with uncorrected distance visual acuity of ≥20/20 increased significantly by 36%; the mean refractive astigmatism magnitude decreased significantly, and the percentages of eyes with refractive cylinder of ≤0.25 diopters (D) and ≤0.50 D increased significantly by 63% and 75%, respectively (all P < .05). The vector magnitude difference between pre- and post-operative refractive astigmatism was 0.88 ± 0.38 D. The postoperative refractive astigmatism had significantly smaller centroid and variance values than the preoperative refractive astigmatism ( P < .05).

CONCLUSIONS

PCRIs are an effective approach for correcting low amounts of residual astigmatism in patients after cataract surgery.

Managing low corneal astigmatism in patients with presbyopia correcting intraocular lenses: a narrative review

Cataract surgery has become a refractive procedure in which emmetropia is the goal, with the implantation of extended depth-of-focus or multifocal intraocular lenses (IOLs) being the commonly selected option to restore vision beyond the far distance. The selection criteria for implanting these lenses can differ from those for monofocal IOLs and even between technologies, as eye characteristics can affect postoperative visual performance. Corneal astigmatism is an eye characteristic that can affect visual performance differently, depending on the implanted IOL. The magnitude of corneal astigmatism, the tolerance of the IOL to this astigmatism, economic aspects, comorbidities, and the efficacy of astigmatism treatment are factors that can make surgeons' doubt as to what astigmatism treatment should be applied to each patient. This review aims to summarize the current evidence related to low astigmatism tolerance in presbyopia-correcting lenses, the efficacy achieved through corneal incisions, and their comparison with the implantation of toric IOLs.

Comparison of long-term astigmatic changes following cataract surgery among types of corneal astigmatism

AIMS

To examine whether long-term corneal astigmatic changes after stabilisation of surgically induced astigmatism (SIA) following cataract surgery differ among eyes having against-the-rule (ATR), with-the-rule (WTR), and oblique astigmatism.

METHODS

Anterior corneal astigmatism of 390 eyes in 390 patients (130 eyes each having ATR, WTR and oblique astigmatism) who underwent phacoemulsification with a horizontal clear corneal or scleral incision and 390 eyes in 390 control patients without surgery were examined using an auto-keratometer on the day that SIA stabilised (baseline) and at ≥8 years post baseline. Changes in corneal astigmatism during the ≥8 years post baseline were decomposed to vertical/horizontal (Rx) and oblique astigmatism components (Ry), and compared among baseline types of astigmatism and between eyes with and without surgery.

RESULTS

The mean corneal astigmatic changes (Rx and Ry) showed an ATR shift of 0.2-0.3 D during the ≥8 years post baseline, which did not differ significantly among the ATR, WTR and oblique astigmatism groups in eyes with and without surgery. In the ATR, WTR and oblique groups, the mean Rx and Ry did not differ significantly between eyes with and without surgery. Double angle plots revealed an equivalent degree of ATR change in the ATR, WTR and oblique groups between eyes with and without surgery.

CONCLUSION

Long-term corneal astigmatic changes towards ATR astigmatism occurred to a similar extent in eyes having ATR, WTR, oblique astigmatism and were comparable between eyes with and without surgery, suggesting that astigmatism type need not be considered when planning astigmatism correction.

Outcome of astigmatism correction using femtosecond laser combined with cataract surgery: penetrating vs intrastromal incisions

PURPOSE

To compare the effectiveness of penetrating vs intrastromal femtosecond laser corneal relaxing incisions (CRI) in reducing corneal astigmatism during cataract surgery.

SETTINGS

Baylor College of Medicine and Mercy Clinic Eye Specialists.

DESIGN

Prospective randomized study.

METHODS

Subjects were randomly assigned to undergo paired penetrating (8-mm optical zone (OZ) at one center and 9-mm OZ at the other) or intrastromal CRIs (8-mm OZ at both centers). The lengths of the CRIs were based on published nomograms but modified to take into account posterior corneal astigmatism. Vector analysis was performed, and net corneal changes along the CRI meridian were calculated. Multiple regression analysis was performed to assess factors contributing to net corneal changes.

RESULTS

Preoperatively, 9-18% of eyes had corneal astigmatism of ≤ 0.5 D, and 76-93% of eyes had postoperative refractive astigmatism of ≤ 0.5 D (P<0.05). Both penetrating and intrastromal CRIs produced significant mean net corneal changes along the CRI meridian (-0.49 D to -1.21 D), and 71% - 84% of eyes had postoperative astigmatism vector prediction errors of ≤0.50 D. The 8-mm penetrating CRIs induced greater net corneal changes but more eyes with overcorrection than did the intrastromal and 9-mm penetrating CRIs (all P<0.05). Greater net corneal changes occurred with longer CRI length, higher preoperative corneal astigmatism magnitude, and preoperative against-the-rule corneal astigmatism. Nomograms based on anterior and total corneal astigmatism are proposed.

CONCLUSIONS

Both penetrating and intrastromal CRIs were effective in reducing corneal astigmatism during cataract surgery.

Toric intraocular lenses: Expanding indications and preoperative and surgical considerations to improve outcomes

Since the introduction of the first toric intraocular lens (IOLs) in the early 1990s, these lenses have become the preferred choice for surgeons across the globe to correct corneal astigmatism during cataract surgery. These lenses allow patients to enjoy distortion-free distance vision with excellent outcomes. They also have their own set of challenges. Inappropriate keratometry measurement, underestimating the posterior corneal astigmatism, intraoperative IOL misalignment, postoperative rotation of these lenses, and IOL decentration after YAG-laser capsulotomy may result in residual cylindrical errors and poor uncorrected visual acuity resulting in patient dissatisfaction. This review provides a broad overview of a few important considerations, which include appropriate patient selection, precise biometry, understanding the design and science behind these lenses, knowledge of intraoperative surgical technique with emphasis on how to achieve proper alignment manually and with image-recognition devices, and successful management of postoperative complications.

Astigmatic Results of a Diffractive Trifocal Toric IOL Following Intraoperative Aberrometry Guidance

Purpose

To determine if intraoperative aberrometry (IA) improves astigmatic outcomes for trifocal toric IOL (TTI) cases.

Patients and Methods

This was a retrospective study examining 137 eyes that underwent cataract extraction and TTI implantation using femtosecond laser, digital registration, and IA. Final cylinder power and axis of placement were determined by IA. Monocular uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), and refractive data were collected at 3 months. Postoperative residual astigmatism (PRA) determined by manifest refraction was compared to back-calculated residual astigmatism (BRA) using the cylinder power calculated preoperatively.

Results

Postoperatively, 97.8% of eyes had IA PRA ≤ 0.50D and 80.3% had BRA ≤ 0.50 D, a difference of 17.5%. Mean PRA for IA was 0.07 D ± 0.19 (range 0.00–1.00 D) compared to BRA 0.31 D ± 0.33 (range 0.00–1.34 D) (P < 0.001). Cylinder power was changed in 50.4% of cases based upon IA. Postoperative mean UDVA (LogMAR) was 0.04 ± 0.09 (range −0.12–0.30 logMAR), and 65% of eyes were ≤ 0.0, 85% ≤ 0.1, and 99% ≤ 0.18.

Conclusion

The proportion of eyes with PRA ≤ 0.50 D and mean PRA was significantly lower using IA versus the preoperative planned cylinder power.

Refractive and Visual Outcomes After Implantation of a Secondary Toric Sulcus Intraocular Lenses

Purpose

To evaluate the rotational stability, visual acuity and refractive error after sulcus implantation of a secondary toric IOL.

Setting

One clinical practice in Haugesund, Norway.

Design

Non-interventional single-arm diagnostic study.

Methods

Eligible subjects who had previous successful primary cataract or refractive lens exchange surgery in one or both eyes and the AddOn^® secondary toric IOL implanted in the sulcus were evaluated at a single postoperative diagnostic visit to measure visual outcomes. Subjects with surgical complications (either primary or secondary) or pathology that would affect best-corrected visual acuity (eg, amblyopia) were excluded. Clinical evaluations at the diagnostic visit included measurement of visual acuity, manifest refraction and IOL orientation.

Results

Eighteen eyes were evaluated. After secondary IOL implantation, mean residual refractive astigmatism was significantly reduced (1.66 ± 0.92 to 0.32 ± 0.25 D). There was no appreciable change in the spherical equivalent refraction. Sixteen of 18 eyes (89%) had residual refractive astigmatism ≤0.50D, and no eye had more than 0.75D after secondary IOL implantation. Mean UCVA was 0.00 ± 0.03 logMAR, with no eyes worse than 0.10. Mean BCVA was −0.05 ± 0.03 logMAR (20/20+2), with all eyes having BCVA of 0.00 logMAR. The mean change in orientation was near zero, with a mean absolute change of 4.9 ± 3.7 degrees. Sixteen of 18 eyes (89%) had a lens orientation ≤10 degrees from intended, with no eye oriented more than 13 degrees from intended.

Conclusion

The AddOn^® toric sulcus IOL significantly reduced postoperative refractive astigmatism in patients with high astigmatism after their primary cataract or RLE surgery, providing very good uncorrected distance vision.

Comparative effects of various types of toric intraocular lenses on astigmatism correction

BACKGROUND

Currently, various types of toric intraocular lenses (IOL) have been manufactured and can be divided into three types according to the location of correction component; front-toric IOL (correction on anterior IOL surface), back-toric IOL (correction on posterior IOL surface), and bi-toric IOL (correction on both anterior and posterior IOL surfaces). In this study, we aimed to investigate the effectiveness of reducing corneal astigmatism of either normal or post-penetrating keratoplasty (PKP) corneas according to the type of implanted toric IOLs.

METHODS

Medical records were retrospectively reviewed in 370 patients who had undergone phacoemulsification with posterior chamber toric IOL insertion (front-toric IOL, back-toric IOL or bi-toric IOL). Subjects were divided into 2 groups; subjects who had no history of corneal disease with corneal astigmatism more than 1.00 diopters (D) (G1) and subjects who received previous PKP with all corneal sutures removed and had corneal astigmatism more than 1.25 D (G2). Preoperatively intended target from SRK/T was evaluated. Refractive astigmatism and its vector analysis (J0, J45), mean numerical error (MNE) and mean absolute error (MAE) were assessed at least a month after cataract surgery.

RESULTS

Mean preoperative corneal astigmatisms were 2.2 D and 4.0 D in G1 and G2, respectively. There was significant reduction of mean postoperative refractive astigmatism to 0.89 D in G1 and to 2.33 D in G2. In G1, bi-toric IOL showed significantly more improved refractive astigmatism than back-toric IOL. In G2, no difference in refractive astigmatism according to toric IOL type was observed. While G2 showed no difference in MNE among toric IOLs, in G1, bi-toric IOL showed significant hyperopic shift compared to back-toric IOL. In both groups, there was no significant difference in MAE according to type of IOL. No postoperative complications were observed.

CONCLUSION

Our study suggests that all types of toric IOL are beneficial in correcting astigmatism of normal and post-PKP corneas. Noticeably, bi-toric IOL showed significantly better results in refractive astigmatism than back-toric IOL in normal cornea. However, bi-toric IOL showed a more hyperopic shift compared to back-toric IOL. Among post-PKP corneas, all types of toric IOL showed similar results.

Comparing Visual Acuity, Low Contrast Acuity and Contrast Sensitivity After Trifocal Toric and Extended Depth of Focus Toric Intraocular Lens Implantation

Purpose

The aim of this study was to compare visual acuity at various distances (far, intermediate and near), low contrast acuity and contrast sensitivity after trifocal toric and extended depth of focus (EDOF) toric intraocular lens (IOL) implantation.

Patients and Methods

This was a non-interventional two-arm comparative study of visual outcomes after uncomplicated bilateral cataract or refractive lens exchange surgery with IOL implantation between 6 months and 5 years before a single diagnostic examination visit. There was no masking and no control group. Subjects had to have uncorrected distance visual acuity (UDVA) of 20/40 (0.3 logMAR) or better measured at the time of their study visit. Clinical evaluations included the manifest refraction, visual acuity (VA) at distance, intermediate (60 cm) and near (40 cm), low contrast (10%) VA and contrast sensitivity.

Results

A total of 50 bilaterally implanted patients (25 trifocal, 25 EDOF) were examined; the two groups had similar characteristics, including corneal astigmatism. Postoperative refractive outcomes were also similar. There were no statistically significant differences in distance or intermediate VA between groups, but the trifocal group had significantly better near VA both uncorrected (p = 0.009) and distance-corrected (p = 0.014). There were no statistically significant differences in the low contrast acuity measures between IOLs at either distance or 40 cm, with or without glare. Contrast sensitivity in mesopic and photopic conditions was similar.

Conclusion

The trifocal and EDOF toric IOLs performed similarly for all measures except near VA, where the trifocal toric provided significantly better acuity. For subjects interested in reducing spectacle independence at near, this may be an important consideration.

Correcting Corneal Astigmatism with Corneal Arcuate Incisions during Femtosecond Laser Assisted Cataract Surgery

BACKGROUND:

Astigmatic management is an important step to achieve the best visual quality after refractive cataract surgery. Nowadays, along with progress in cataract surgery, the femtosecond laser can produce the arcuate incisions high precisely that help the astigmatic correction. In Vietnam, it has not yet any study about this issue, so we perform this study.

AIM:

To assess the efficacy and safety of arcuate corneal incisions in treatment corneal astigmatism during femtosecond laser-assisted cataract surgery.

METHODS:

In this clinical interventional study, forty-five cases with cataract and corneal astigmatism (> 0.50D) were treated with corneal arcuate incisions and femtosecond-laser assisted cataract surgery in Vietnam National Institute of Ophthalmology, from January 2017 to May 2018. The uncorrected and corrected distance visual acuity, refraction spherical equivalent, corneal astigmatism were measured (using an OPD-Scan III topographer) before, 1 week and 3 months after surgery. Some features of arcuate corneal incisions (quantity, depth, length and morphology), spectacle independence at a distance and complications were recorded.

RESULTS:

The rate of postoperative spherical refraction equivalent was within ± 0.50D and ± 1.0D at 3 months (in 95.6% and 100% of the eyes respectively). Mean length of arcuate corneal incisions was 53.78o ± 17.683o (range: 20o to 85o). The average of preoperative corneal astigmatism was 1.65 ± 0.83D, decreased to 0.59 ± 0.549D in the third month after surgery. Surgical induced astigmatism was 1.05 ± 0.449D and lower than preoperative corneal astigmatism (1.65 ± 0.83D), thereby this indicated undercorrection. However, the rate of spectacle independence was 82.3%, and no complications were recorded.

CONCLUSION:

Correcting of corneal astigmatism in femtosecond laser-assisted cataract surgery combined with the formation of the arcuate incisions is a new and modern method for high safety and efficacy.

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.

Femtosecond laser-assisted capsulotomy with capsular marks for toric IOL alignment: Comparison of tensile strength with standard femtosecond laser capsulotomy

PURPOSE

To compare the capsulotomy rim strength with capsular marks (CMs) to the rim strength without CMs in porcine eyes, and to demonstrate the practicality of CMs for intraoperative toric intraocular lens (IOL) alignment.

SETTING

LENSAR facility, Orlando, Florida, USA.

DESIGN

Laboratory study.

METHODS

The biomechanical strength of the capsulotomy with CMs was tested under two different load orientations (orthogonal to or in-line with CMs). Thirty-six porcine eyes were randomly assigned to three treatment cohorts: (1) standard capsulotomy with no CMs, (2) capsulotomy with CMs for in-line tensile testing and (3) capsulotomy with CMs for orthogonal tensile testing. Study parameters were capsulotomy break force and maximum extensibility. The ease of using CMs for toric IOL alignment was also evaluated.

RESULTS

There was no significant difference between the mean break force for standard capsulotomy (180.57 mN ± 22 [SD]), capsulotomy with CMs with orthogonal load (178.04 ± 20 mN, P = 1.000), and with in-line load (181.05 ± 15 mN, P = 1.000). Likewise, the mean extensibility at the break point for standard capsulotomy (6.47 ± 0.33 mm) was equivalent to the mean extensibility with CMs with orthogonal load (6.49 ± 0.45 mm, P = 1.000) and with in-line load (6.3 ± 0.47 mm, P = .960). In the implanted eyes, toric IOLs were found to be easily aligned with the CMs.

CONCLUSION

The femtosecond laser capsulotomies with CMs were equivalent in tensile strength and extensibility to standard femtosecond laser capsulotomies and showed high potential for effective alignment of toric IOLs.

Influence of corneal diameter on surgically induced astigmatism in small-incision cataract surgery

OBJECTIVE

Clear corneal incisions (CCI) in cataract surgery create a variable amount of surgically induced astigmatism (SIA). As refractive outcomes become increasingly important, it is necessary to understand factors that impact SIA and refractive surprises. In this study, we evaluate the effect of horizontal corneal diameter (white-to-white, WTW) on SIA in 2.2 mm small-incision cataract surgery.

DESIGN

Prospective study at an academic-university-based outpatient clinic (Duke Eye Center).

PARTICIPANTS

We enrolled adults ≥18 years of age without prior corneal surgery or corneal pathology undergoing cataract surgery with a single surgeon (R.R.V.).

METHODS

All surgeries were uncomplicated and performed through a manually constructed, limbal, temporal, or superotemporal 2.2 mm CCI. Enrolled participants received standard-of-care evaluations and postoperative management. SIA was calculated at the first postoperative month using the Jaffe and Clayman vector analysis equation.

RESULTS

We enrolled 43 subjects (55 eyes) with a mean age of 71 years with WTW corneal diameter values ranging from 11.34 to 12.99 mm obtained from Lenstar^® (Haag-Streit Group, Koeniz, Switzerland). Postoperative SIA ranged from 0.072 to 1.6 D (mean 0.47 D, standard deviation 0.33 D). SIA was plotted against WTW and best fit to a linear regression model with a slope of -0.056 and an R² value of 0.006.

CONCLUSIONS

In this prospective study, WTW diameter had minimal effects on the SIA in uncomplicated small-incisional cataract surgery through a 2.2 mm temporal or superotemporal CCI with a single surgeon. Our findings suggest that corneal diameter does not play a clinically significant role in this population undergoing small-incisional cataract surgery.

Real-world refractive outcomes of toric intraocular lens implantation in a United Kingdom National Health Service setting

BACKGROUND

With increasing availability of toric intraocular lenses (IOL) for cataract surgery, real-world refractive outcome data is needed to aid the counselling of patients regarding lens choice. We aim to assess the outcomes of toric intraocular lens use in the non-specialist environment of a typical United Kingdom NHS cataract service.

METHODS

A retrospective cohort study conducted at the Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, UK. All patients who received a toric IOL implant over a 10 months period. Patients underwent pre-operative corneal marking, phacoemulsification and toric IOL implantation. Biometry was obtained using a Zeiss IOLMaster 500 and the toric IOLs were selected using the manufacturers' online calculators. Post-operative refractions were obtained from optometrist's manifest refraction or by autorefraction. The outcome measures were post-operative unaided visual acuity (UVA), spherical equivalent refraction, cylindrical correction and all complications.

RESULTS

Thirty-two eyes of 24 patients aged 21-86 years (mean 66.4, SD 14.5) were included. UVA was superior to pre-operative best-corrected visual acuity (BCVA) in 81% of eyes, same in 16% and inferior in 3%, resulting in a median improvement of 0.20 LogMAR (IQR 0.10 to 0.30). 56%, 81%, 94% and 100% of eyes were within ±0.5, ±1.0, ±1.5 and ±2.0 D of predicted spherical equivalent, respectively. Three (9%) eyes required further surgery to rectify significant IOL rotation.

CONCLUSIONS

Reduced cylindrical correction and improved UVA could be expected in the majority of patients undergoing toric IOL implantation. Patients should be counselled about the risk of lens rotation.

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

Purpose

The purpose of this study was to determine an arcuate incision (AI) nomogram to treat astigmatism during femtosecond laser-assisted cataract surgery.

Methods

This is a retrospective, cohort study. Femtosecond laser (FSL)-assisted transepithelial AIs were created at a 9.0 mm optical zone, 80% depth, centered on the limbus. We modified the manual Donnenfeld limbal relaxing incision nomogram to 70% for with-the-rule (WTR), 80% for oblique (OBL), and 100% for against-the-rule (ATR) astigmatism. The correction index (CI) equaled AI-induced astigmatism/target-induced astigmatism. Measures included preoperative keratometric corneal cylinder (Pre Kcyl), postoperative Kcyl (Post Kcyl), and postoperative residual refractive astigmatism (Post RRA).

Results

Mean Pre Kcyl and 1–2 months Post RRA in 161 eyes of 116 patients were 0.626±0.417 diopters (D) (range 0.5–2 D), and 0.495±0.400 D (range 0–1.5 D), respectively. Mean absolute astigmatic changes (Pre Kcyl–Post Kcyl) without accounting for axis change in the WTR, ATR, and OBL groups were 0.165±0.383 D (P<0.001), 0.374±0.536 D (P<0.001), and 0.253±0.416 D (P=0.02), respectively. Mean absolute astigmatic changes using RRA as the postoperative measurement (Pre Kcyl–Post RRA) without accounting for axis change were 0.440±0.461 D (P<0.001), 0.238±0.571 D (P<0.05), 0.154±0.450 (P=0.111) in WTR, ATR, and OBL groups, respectively. CIs for WTR, ATR, and OBL were 0.53, 1.01, and 0.95, respectively. There were no intraoperative or postoperative complications related to the AIs.

Conclusion

Transepithelial FSL-AIs using the modified Donnenfeld nomogram show potential for management of mild to moderate corneal astigmatism. An increase in the magnitude or reduction of the optical zone size for the treatment of WTR and ATR astigmatism for this nomogram may further improve refractive accuracy.

Tomographic Analysis of Anterior and Posterior and Total Corneal Refractive Power Changes After Femtosecond Laser-Assisted Keratotomy

PURPOSE

To analyze the effect of penetrating femtosecond laser-assisted keratotomy (pFLAK) during laser lens surgery on anterior and posterior corneal astigmatism and total corneal refractive power (TCRP) astigmatism (CA_ant, CA_post, CA_TCRP) measured with Scheimpflug tomography.

DESIGN

Prospective, interventional case series.

METHODS

This institutional study included 27 eyes of 23 patients (aged 65 ± 8 years) with low-to-moderate CA_TCRP determined with Scheimpflug tomography (Pentacam HR; Oculus, Wetzlar, Germany) after penetrating femtosecond laser-assisted keratotomy (pFLAK) and laser lens surgery. The CA_ant, CA_post, and CA_TCRP were determined before and 1 and 3 months after surgery. Vector analysis according to the Alpins method was used to calculate surgically induced astigmatism (SIA).

RESULTS

The mean preoperative CA_ant (0.97 ± 0.30 diopter [D]) was significantly reduced to 0.63 ± 0.34 D (P < .001). SIA_ant was 0.71 ± 0.37 D. The CA_post showed no significant change, from preoperative 0.26 ± 0.12 D to 0.26 ± 0.10 D postoperatively (P = .625). In line with this finding, SIA_post was low (0.12 ± 0.07 D). The CA_TCRP showed similar results as CA_ant.

CONCLUSION

pFLAKs planned according to Scheimpflug-based CA_TCRP result in a significant reduction of the CA_ant and CA_TCRP, but do not affect the posterior corneal curvature significantly, as measured by Scheimpflug tomography. Further research is required to develop a new valid nomogram for laser-assisted lens surgery.

Effect of Limbal Relaxing Incisions on Corneal Aberrations

PURPOSE

To study the effect of limbal relaxing incisions on corneal aberrations after phacoemulsification with aspheric intraocular lens (IOL) implantation.

METHODS

Forty-five eyes underwent microincision cataract surgery with on-axis phacoemulsification incision. These eyes were divided into two groups: limbal relaxing incision group (23 eyes) and control group (22 eyes). In the limbal relaxing incision group, a single limbal relaxing incision was performed on the steepest meridian of corneal topography and the degrees of arc were determined using the DONO-Donnenfeld nomogram. The eyes in the control group were operated on by microincision cataract surgery without limbal relaxing incision. Corneal topography and wavefront analysis over 6-mm pupil size were performed preoperatively and 1 month postoperatively in both groups. Target induced astigmatism vector, surgically induced astigmatism vector, difference vector, magnitude of error, flattening effect, and torque were analyzed using the Alpins vectorial method.

RESULTS

The limbal relaxing incision group showed significant reduction in topographic astigmatism by 51.87% of preoperative topographical astigmatism (P < .0001). The mean surgically induced astigmatism of limbal relaxing incision was 1.29 ± 0.71 diopters (D), which was close to the mean target induced astigmatism (1.33 ± 0.20 D), whereas the control group did not show a significant change in topographic astigmatism (0.17 ± 0.11 D; P = .73). Higher order aberrations of the cornea did not show significant change in either group except quatrefoil aberration, which significantly increased in the limbal relaxing incision group but not in the control group, with no significant difference between the two groups regarding corneal aberrations.

CONCLUSIONS

Limbal relaxing incision is an effective method in reducing corneal astigmatism with neutral effect on corneal aberrations.

Three Methods for Correction of Astigmatism during Phacoemulsification

PURPOSE

To compare the safety and efficacy of three methods for correcting pre-existing astigmatism during phacoemulsification.

METHODS

This prospective, comparative, non-randomized study was conducted from March 2010 to January 2011, and included patients with keratometric astigmatism ≥1.25 D undergoing cataract surgery. Astigmatism was corrected using the following approaches: limbal relaxing incisions (LRI) on the steep meridian, extension and suturing of the phaco incision created at the steep meridian (extended-on-axis incision, EOAI), and toric intraocular lens (tIOL) implantation. Keratometric and refractive astigmatism were evaluated 1, 8, and 24 weeks postoperatively.

RESULTS

Eighty-three eyes of 72 patients (35 male and 37 female) with mean age of 62.4 ± 14.3 (range, 41-86) years were enrolled. The astigmatism was corrected by using the LRI, EOAI and tIOL implantation methods in 17, 33 and 33 eyes, respectively. Postoperative uncorrected distance visual acuity (UDVA) was significantly improved in all three groups. The difference in postoperative UDVA was not statistically significant among the study groups throughout follow-up except at week 24, when UCVA was significantly better in the tIOL group as compared to the EOAI group (P = 0.024). There is no statistically significant difference of correction index and index of success between three groups at week 24 (P = 0.085 and P = 0.085 respectively).

CONCLUSION

There was no significant difference in astigmatism reduction among the three methods of astigmatism correction during phacoemulsification. Each of these methods can be used at the discretion of the surgeon.

Relationship between age, corneal astigmatism, and ocular dimensions with reference to astigmatism in eyes undergoing routine cataract surgery

PURPOSE

To assess the relationship between age, corneal astigmatism, and ocular dimensions with reference to astigmatism correction during cataract surgery.

METHODS

In this cross-sectional study of right eyes of 2247 consecutive patients attending cataract surgery preassessment, data on patient demographics, axial length (AL), anterior chamber depth (ACD), and keratometric astigmatism were collected. Astigmatism was further analyzed as against-the-rule (ATR: steepest meridian 180±30°), with-the-rule (WTR: 90±30°), and oblique (OB: 30-60°or 120-150°).

RESULTS

Mean age, AL, and ACD were 72.28±13.84 years, 23.99±1.85 mm and 3.08 ±0.52 mm, respectively. In all, 20.4% eyes had ≤0.50 diopters (D), 55.2% had 0.51-1.50 D, 7.9% had 2.01-3.00 D, and 3.7% eyes had >3.00 D of astigmatism. Overall, 44.2% of eyes had corneal astigmatism >1.00 D. Average astigmatism in age ranges 40-49, 50-59, 60-69, 70-79, 80-89, and 90+ years were 0.82, 1.04, 1.04, 1.02, 1.15 and 2.01 D, respectively. The magnitude of preoperative astigmatism positively correlated with age (P<0.0001), with increasing and decreasing prevalence of ATR and WTR astigmatism, respectively, with advancing age. The magnitude of ATR astigmatism inversely correlates to AL (P<0.0001). ATR astigmatism is more prevalent with increasing magnitude of astigmatism (P<0.0001).

CONCLUSIONS

A majority of patients for cataract surgery have astigmatism between 0.51 and 1.5 D. ATR astigmatism increases, whereas WTR decreases with age. ATR astigmatism inversely correlates to AL. With increasing age, the magnitude of astigmatism increases and ATR astigmatism becomes increasingly prevalent. The likelihood of a patient requiring astigmatic correction increases with age.

Comparison of astigmatism correction using either peripheral corneal relaxing incisions or toric intraocular lenses

PURPOSE

To compare the efficacy and short-term stability of toric intraocular lenses (tIOL) and peripheral cornea relaxing incisions (PCRI) during phacoemulsification.

METHODS

Patients with preexisting corneal astigmatism had cataract surgery either with tIOL (AcrySof Toric) (39 eyes of 35 patients) or standard intraocular lens (AcrySof) + PCRIs (38 eyes of 33 patients). Patients were retrospectively evaluated for manifest refraction, corneal topography, and uncorrected and corrected visual acuities preoperatively and at postoperative 1 and 6 months. The Alpins vectorial method was used to analyze the target induced astigmatism (TIA) and surgically induced astigmatism (SIA), magnitude of error (the difference between the magnitude of SIA and TIA) (ME), and correction index.

RESULTS

Mean preoperative corneal astigmatism was 2.21 ± 1.32 D in the tIOL group and 2.24 ± 0.96 D in the PCRI group; the difference was not significant. The decrease in astigmatism was significant in both groups at last follow-up (64% tIOL group, 32% PCRI group, p&lt;0.01, Wilcoxon signed rank test). The mean remaining refractive astigmatism was significantly higher in the PCRI group than in the tIOL group at 1-month (1.42 ± 1.22, 0.89 ± 0.68, respectively) and 6-month follow-ups (1.75 ± 1.37 D, 0.92 ± 0.72, respectively) (p&lt;0.01). The mean ME was significantly lower (-0.35 versus -0.88) with a higher correction index (0.96 versus 0.56) in the tIOL group at 6 months postoperatively.

CONCLUSIONS

Both tIOL implantation and using PCRI were effective methods to reduce preoperative astigmatism at the time of the cataract surgery. However, tIOLs provided better remaining astigmatism with a more stable refraction than PCRI.

Long-term outcomes of limbal relaxing incisions during cataract surgery: aberrometric analysis

PURPOSE

To compare the final changes in corneal wavefront aberration by limbal relaxing incisions (LRIs) after cataract surgery.

METHODS

This prospective cumulative interventional nonrandomized case study included cataract and astigmatic patients undergoing LRIs and phaco with intraocular lens implantation. LRIs were planned using Donnenfeld nomogram. The root mean square of corneal wave aberration for total Z(n,i)(1≤n≤8), astigmatism Z(2,±1), coma Z(3-5-7,±1), trefoil Z(3-5-7,±2), spherical Z(4-6-8,0), and higher-order aberration (HOA) Z(3≤n≤8) was examined before and 3 years after surgery (optical path difference-Scan II [OPD-Scan II)]. Uncorrected distance visual acuity and best-corrected distance visual acuity (CDVA) for distance, keratometric cylinder, and variations in average corneal power were also analyzed.

RESULTS

Sixty-four eyes of 48 patients were included in the study. Age ranged from 42 to 92 years (70.6±8.4 years). After LRIs, uncorrected distance visual acuity and best-corrected distance visual acuity improved statistically (P<0.01). The keratometric cylinder value decreased by 40.1%, but analysis of KP90 and KP135 polar values did not show any decrease that could be statistically confirmed (P=0.22 and P=0.24). No significant changes were detected in root mean square of total (P=0.61) and HOAs (P=0.13) aberrations. LRIs did not induce alteration in central corneal power confirming a 1:1 coupling ratio.

CONCLUSION

LRIs determined a nonsignificant alteration of corneal HOA. Therefore, LRIs can be still considered a qualitatively viable mean in those cases where toric intraocular lenses are contraindicated or not available. Yet, the authors raise the question of nonpersonalized nomograms, as in the present study, LRIs did not reach the preset target cylinder.

The evolution of corneal and refractive surgery with the femtosecond laser

The use of femtosecond lasers has created an evolution in modern corneal and refractive surgery. With accuracy, safety, and repeatability, eye surgeons can utilize the femtosecond laser in almost all anterior refractive procedures; laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), penetrating keratoplasty (PKP), insertion of intracorneal ring segments, anterior and posterior lamellar keratoplasty (Deep anterior lamellar keratoplasty (DALK) and Descemet's stripping endothelial keratoplasty (DSEK)), insertion of corneal inlays and cataract surgery. As the technology matures, it will push surgical limits and open new avenues for ophthalmic intervention in areas not yet explored. As we witness the transition from femto-LASIK to femto-cataract surgery it becomes obvious that this innovation is here to stay. This article presents some of the most relevant advances of femtosecond lasers to modern corneal and refractive surgery.

Influence of Patient Age at Surgery on Long-Term Corneal Astigmatic Change Subsequent to Cataract Surgery

PURPOSE

To examine whether long-term corneal astigmatic change with age after cataract surgery depends on patient age at the time of surgery, and to evaluate whether this change is different from that in eyes that did not undergo surgery.

DESIGN

Retrospective cohort study.

METHODS

A total of 437 eyes that underwent phacoemulsification with a 4.1-mm horizontal corneoscleral incision more than 11 years ago and 600 control eyes without surgery were divided into 4 age groups: (1) 60 years or younger, (2) 61-65 years, (3) 66-70 years, and (4) 71 years or older. The corneal astigmatic change between baseline and 5 years after baseline, between 5 and 10 years, and between baseline and 10 years, as calculated using the polar (x-y) coordinate analysis, were compared among the age groups and between eyes with and without surgery.

RESULTS

Corneal astigmatic change, expressed as x- and y-coordinates, showed an against-the-rule change of 0.2-0.4 diopter during the 10 years in all age groups of the surgery and nonsurgery groups. Using multivariate analysis of variance, the mean x- and y-coordinates did not differ significantly among the age groups in either the surgery or nonsurgery groups (P ≥ .4112). Furthermore, the mean x- and y-coordinates did not differ significantly between the surgery and nonsurgery groups in any age group (P ≥ .1359).

CONCLUSION

Long-term corneal astigmatic change with age after cataract surgery does not differ significantly depending on patient age at the time of surgery, and is comparable to that of eyes without surgery.

Factors Influencing Efficacy of Peripheral Corneal Relaxing Incisions during Cataract Surgery

Purpose. To evaluate influencing factors on the residual astigmatism after performing peripheral corneal relaxing incisions (PCRIs) during cataract surgery. Methods. This prospective study included patients who were scheduled for cataract surgery with PCRIs. Optical biometry (IOLMaster 500, Carl Zeiss Meditec AG, Germany) was taken preoperatively, 1 week, 4 months, and 1 year postoperatively. Additionally, corneal topography (Atlas model 9000, Carl Zeiss Meditec AG, Germany), ORA (Ocular Response Analyzer, Reichert Ophthalmic Instruments, USA), and autorefraction (Autorefractometer RM 8800 Topcon) were performed postoperatively. Results. Mean age of the study population (n = 74) was 73.5 years (±9.3; range: 53 to 90) and mean corneal astigmatism preoperatively was -1.82 D (±0.59; 1.00 to 4.50). Mean corneal astigmatism was reduced to 1.14 D (±0.67; 0.11 to 3.89) 4 months postoperatively. A partial least squares regression showed that a high eccentricity of the cornea, a large deviation between keratometry and topography, and a high preoperative astigmatism resulted in a larger postoperative error concerning astigmatism. Conclusions. PCRI causes a reduction of preoperative astigmatism, though the prediction is difficult but several factors were found to be a relevant source of error.

Comparison of visual and refractive outcomes after bilateral implantation of toric intraocular lenses with or without a multifocal component

PURPOSE

To compare visual outcomes between patients with a multifocal toric intraocular lens (IOL) and those with a monofocal toric IOL.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

DESIGN

Prospective case-control series.

METHODS

Eyes with preoperative corneal astigmatism between 0.75 diopter (D) and 2.82 D scheduled for implantation of a diffractive multifocal toric IOL (Restor SND1T) or monofocal toric IOL (Acrysof SN6AT) were recruited. Three months postoperatively, visual acuity at various distances, contrast visual acuity, and refractive outcomes were examined.

RESULTS

Each group comprised 66 eyes (33 patients). Postoperatively, the mean refractive astigmatism decreased to 0.71 D in the multifocal group and 0.74 D in the monofocal group. The mean monocular and binocular uncorrected and corrected near visual acuity at 0.3 m and intermediate visual acuity at 0.5 m were significantly better in the multifocal group than in the monofocal group (P≤.0011). The uncorrected and corrected visual acuities at other distances were similar between groups except at 1.0 m. Binocular photopic and mesopic contrast visual acuities at high to moderate contrasts did not differ significantly between groups; however, acuities at low contrasts were worse in the multifocal group (P≤.0429).

CONCLUSION

Diffractive multifocal toric IOL implantation decreased refractive astigmatism to an acceptable range in eyes with moderate corneal astigmatism and provided useful visual acuity (≥20/40) at any distance and significantly better near and intermediate visual acuity than a monofocal toric IOL.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Long-term clinical outcomes of toric intraocular lens implantation in cataract cases with preexisting astigmatism

PURPOSE

To evaluate the long-term clinical outcomes and rotational stability of toric intraocular lenses (IOLs) to correct preexisting astigmatism in cataract patients.

SETTING

Kitasato University Hospital, Kanagawa, Japan.

DESIGN

Prospective observational study.

METHODS

Phacoemulsification with implantation of a toric IOL (Acrysof IQ toric SN6AT) was performed in cataract patients with corneal astigmatism. The postoperative follow-up was up to 2 years.

RESULTS

This study enrolled 378 eyes of 302 patients with a mean age of 63.4 years ± 16.9 (SD). The corrected distance visual acuity 3 months postoperatively was 20/25 or better in 94.7% of eyes. The mean refractive cylinder was -1.92 ± 1.45 diopters (D) preoperatively, -0.59 ± 0.62 D 3 months postoperatively (322 eyes), and -0.67 ± 0.90 D at 2 years (73 eyes). There were statistically significant differences between the preoperative and 3-month postoperative measurements (P<.001, Wilcoxon signed-rank test). The mean IOL misalignment was 4.1 ± 3.0 degrees 2 years postoperatively. The mean IOL rotation was 4.5 ± 4.9 degrees within 1 day postoperatively. The rotation was more than 20 degrees in 6 eyes, all of which had an axial length (AL) of more than 25.0 mm. All rotations occurred within 10 days postoperatively.

CONCLUSIONS

Toric IOLs were effective in reducing preexisting corneal astigmatism and had overall good rotational stability. A large degree of IOL rotation might occur in eyes with a relatively long AL, especially during the early postoperative period. The 6 rotated IOLs were implanted to correct with-the-rule astigmatism.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Effect of preoperative corneal astigmatism orientation on results with a toric intraocular lens

PURPOSE

To compare the Acrysof IQ toric intraocular lens (IOL) and the Acrysof IQ aspheric nontoric IOL and evaluate the effect of preoperative corneal astigmatism orientation on results.

SETTING

Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.

DESIGN

Comparative case series.

METHODS

This retrospective chart review comprised patients with cataract and preoperative corneal astigmatism between 1.0 diopter (D) and 2.5 D having toric IOL (toric group) or aspheric nontoric IOL (nontoric group) implantation. Eyes were grouped depending on the preoperative axis of corneal astigmatism; that is, with the rule (WTR), against the rule (ATR), and oblique. Preoperative and postoperative analyses included uncorrected (UDVA) and corrected (CDVA) distance visual acuities and cylindrical power preoperatively and 3 months postoperatively.

RESULTS

The postoperative CDVA was not significantly different between the 2 IOLs; however, the postoperative UDVA was significantly better in the toric group than in the nontoric group (P<.0001). The postoperative residual cylindrical power was significantly smaller in the toric group (P<.0001). In eyes with ATR and oblique astigmatism, the mean postoperative UDVA was significantly better in the toric group, whereas there were no differences between the 2 groups in patients with WTR astigmatism.

CONCLUSIONS

There was significant improvement in postoperative cylinder and UDVA with toric IOLs compared with nontoric IOLs. With a superior corneal incision, the benefits of astigmatism correction with the toric IOL were more significant in patients with ATR and oblique astigmatism than in those with WTR astigmatism.

A case of endophthalmitis associated with limbal relaxing incision

Limbal relaxing incisions (LRIs) are considered a relatively safe procedure with rapid stabilization and absence of infectious complications. Do we need to readdress this last impression? We report a case of nocardia endophthalmitis associated with an exudate at the site of an LRI in a patient who underwent routine cataract surgery. This case, to the best of our knowledge, is the first report of its kind, stressing the need for a cautious approach to the adoption of this method of astigmatic correction.

Can opposite clear corneal incisions have a role with post-laser in situ keratomileusis astigmatism?

PURPOSE

To evaluate the astigmatic correcting effect of paired opposite clear corneal incisions (OCCIs) on the steep axis in patients with residual astigmatism after laser in situ keratomileusis (LASIK) MATERIALS AND METHODS: Thirty-one eyes of 24 patients with a mean age of 28.4 years ±2.46 (range, 19-36 years) were recruited for the study. Inclusion criteria included residual astigmatism of ≥1.5 diopter (D) after LASIK with inadequate residual stromal bed thickness that precluded ablation. The cohort was divided into two groups; group I (with astigmatism ranging from -1.5 D to -2.5 D) and group II (with astigmatism > -2.5 D). The steep axis was marked prior to surgery. Paired three-step self-sealing opposite clear corneal incisions were performed 1-mm anterior to the limbus on the steep axis with 3.2-mm keratome for group I and 4.1 mm for group II. Patients were examined 1 day, 1 week, 1 month, 3 months and 6 months, postoperatively. Visual acuity, refraction, keratometry, and corneal topography were evaluated preoperatively and postoperatively. Analysis of the difference between groups was performed with the Student t-test. P<0.05 was considered statistically significant.

RESULTS

The mean uncorrected visual acuity (UCVA) improved from 0.35±0.13 (range, 0.1-0.6) to 0.78±0.19 (range, 0.5-1) in group I and from 0.26±0.19 (range, 0.1-0.5) to 0.7±0.18 (range, 0.4-1) in group II. The increase in UCVA was statistically significant in both groups (P=0.001, both cases). The mean preoperative and postoperative keratometric astigmatism in group I was 2.0±0.48 D (range, 1.5-2.5 D) and 0.8±0.37 D (range, 0.1-1.4 D), respectively. The decrease in keratometric astigmatism was highly statistically significant in group II (P=0.001.). Mean surgically induced astigmatic reduction by vector analysis was 1.47±0.85 D and 2.21±0.97 D in groups I and II respectively. There were no incision-related complications.

CONCLUSIONS

Paired OCCIs were predictable and effective in correcting post-LASIK astigmatism and required no extra surgical skill or expensive instruments. OCCIs are especially useful in eyes with insufficient corneal thickness for LASIK retreatment.