Factors that influence the surgical effects of astigmatic keratotomy after cataract surgery

Outcomes of preloaded toric intraocular lens implantation in eyes undergoing phacoemulsification

Purpose

To evaluate the clinical outcomes of preloaded toric intraocular lens (IOLs) implantation in eyes undergoing phacoemulsification.

Methods

This prospective study included 51 eyes of 51 patients with visually significant cataracts and corneal astigmatism ranging between 0.75 and 5.50 D. All patients underwent phacoemulsification with SupraPhob toric intraocular lens implantation under topical anesthesia. The main outcome measures were uncorrected distance visual acuity (UDVA), residual refractive cylinder, spherical equivalent, and IOL stability at 3 months follow-up.

Results

At 3 months, 49% (25/51) of patients had UDVA equal to or better than 20/25 with 100% of eyes achieving better than 20/40. Mean logMAR UDVA improved from 1.02 ± 0.39, preoperatively to 0.11 ± 0.10 at 3 months follow-up (P < 0.001, Wilcoxon signed-rank test). The mean refractive cylinder improved from - 1.56 ± 1.25 D preoperatively to - 0.12 ± 0.31 D at 3 months follow-up (P < 0.001) while the mean spherical equivalent value changed from - 1.93 ± 3.71D preoperatively to - 0.16 ± 0.27D (P = 0.0013). The mean root mean square value for higher order aberrations was 0.30 ± 0.18 μm while the average contrast sensitivity value (Pelli-Robson chart) was 1.56 ± 0.10 log unit, at the final follow-up. The mean IOL rotation at 3 weeks was 1.7 ± 1.61 degrees, which did not change significantly at 3 months (P = 0.988) follow-up. There were no intraoperative or postoperative complications.

Conclusion

SupraPhob toric IOL implantation is an effective method for addressing preexisting corneal astigmatism in eyes undergoing phacoemulsification with good rotational stability.

Ocular Cyclorotation and Corneal Axial Misalignment in Femtosecond Laser-Assisted Cataract Surgery

Purpose: To explore ocular cyclorotation and the source of corneal axial misalignment during femtosecond laser-assisted cataract surgery (FLACS).Methods: Forty-five sequential patients (50 eyes) who had undergone FLACS (LenSx Laser System, Alcon Inc) were recruited. We took screenshots from videos of FLACS to analyze ocular cyclorotation and the real angle between primary incision and secondary incision (RAPS). In addition, crystalline lens tilt and theoretic angle between the primary and secondary incisions (TAPS) was also calculated.Results: The mean absolute value of ocular cyclorotation was 8.03 ± 4.48 degrees (0-19.1 degrees). The crystalline lens tilt was 3.30 ± 1.44 degrees (0.93-6.44 degrees). And the mean preoperative uncorrected visual acuity was 0.89 ± 0.50 LogMAR units. Pearson bivariate correlation analysis showed significant positive correlation between ocular cyclorotation with crystalline lens tilt (r = 0.37, p = .008), and ocular cyclorotation negatively correlated with axial length (r = -0.29, p = .038). In addition, the TAPS was 89.78 ± 1.45 degrees, and the RAPS was 85.68 ± 2.04 degrees. The angle error was 4.11 ± 1.28 degrees (p<0.001).Conclusions: Ocular cyclorotation commonly occurred during FLACS. In addition, increased axial length was associated with less ocular cyclorotation and increased crystalline lens tilt was related to more ocular cyclorotation. Importantly, machinery systemic errors during corneal astigmatism correction by arcuate incision in FLACS should be taken into consideration.

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

PURPOSE

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

SETTING

Twenty surgical sites in the United States.

DESIGN

Retrospective case series.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Evaluation of the effectiveness of combined femtosecond laser-assisted cataract surgery and femtosecond laser astigmatic keratotomy in improving post-operative visual outcomes

Background

To determine postoperative refractive and visual outcomes and astigmatic changes after femtosecond laser astigmatic keratotomy in femtosecond laser-assisted cataract surgery (FLACS).

Methods

This was a prospective interventional case series. Patients with age-related cataract and corneal astigmatism (1.0–3.0D) were treated with FLACS and femtosecond laser astigmatic keratotomy (FSAK). All patients underwent examinations before and 3 months after surgery; visual acuity, subjective and objective refraction, and corneal astigmatism were evaluated and recorded for all patients by using an OPD-Scan III topographer. Vector analysis of astigmatic changes was performed by using the Alpins vector method.

Results

Twenty-five patients were included in the study. Postoperatively, refractive and corneal astigmatism were both reduced significantly (P < 0.05), concurrent with improved uncorrected distance visual acuity and corrected distance visual acuity. The rate of spectacle use was significantly reduced at 3 months postoperatively (P = 0.001). The mean magnitude of the target-induced astigmatism vector (1.40 ± 0.37D) was slightly higher than the mean magnitude of the surgically induced astigmatism vector (1.22 ± 0.46D). The magnitude of error (− 0.18 ± 0.36D), as well as the correction index (0.88 ± 0.29), demonstrated slight undercorrection. The angle of error was 0.85 ± 13.69°, which was close to zero.

Conclusions

Combined femtosecond laser-assisted cataract surgery and astigmatic keratotomy may be an effective approach to manage preoperative astigmatism in cataract surgery, although slight undercorrection may exist during short-term follow-up.

Trial registration

ChiCTR-TRC-14004977

Microincision versus Standard Corneal Incision Phacoemulsification: Visual Outcome

PURPOSE

To compare the visual outcome of microincision (2.2 mm) with standard (2.75 mm) corneal incision phacoemulsification.

METHODS

In this prospective, randomized comparative study, patients with senile cataract and less than 1 diopter (D) of astigmatism were divided into two groups. Group 1 included patients undergoing phacoemulsification with 2.2 mm clear corneal incision and group 2 included those undergoing phacoemulsification with 2.75 mm incision. The steep axis measured on keratometry was marked preoperatively. Phacoemulsification was performed through clear corneal incision on this steep axis. Assessment of visual acuity (distance and near), keratometry, keratometric cylinder, contrast sensitivity by Functional Acuity Contrast Test, and surgically induced astigmatism (SIA) was performed at 1 day, 1 week, and 1, 3, and 6 months.

RESULTS

Fifty eyes of 50 patients were included in the study (29 were male). There were 25 patients in each group. The mean (±SD) SIA calculated by vector analysis method (Holladay-Cravy-Koch) using keratometry value, at the end of 6 months, was 0.54 (±0.18) D and 0.58 (±0.14) D in groups 1 and 2, respectively (p = 0.27). No significant differences were found in the distance and near uncorrected visual acuity, mean keratometry, keratometric cylinder, contrast sensitivity, and SIA at any follow-up visit between two groups.

CONCLUSIONS

In patients with less than 1 D astigmatism undergoing phacoemulsification, both 2.2-mm and 2.75-mm clear corneal incisions result in similar postoperative visual outcome in terms of SIA, keratometry, and contrast sensitivity.

Toric intraocular lens versus monofocal intraocular lens implantation and photorefractive keratectomy: a randomized controlled trial

PURPOSE

To compare the outcomes of phacoemulsification with toric intraocular lens implantation vs phacoemulsification with monofocal intraocular lens implantation followed by photorefractive keratectomy (PRK) for correction of pre-existing astigmatism.

DESIGN

Randomized controlled trial, 6-month study.

METHODS

setting: Institutional.

STUDY POPULATION

Sixty eyes of 52 patients with age-related senile cataract and regular corneal astigmatism ranging from 1.50 to 3.00 diopters, enrolled and randomly allocated in 2 groups based on computer-generated random number table.

INTERVENTION

Group 1 patients underwent phacoemulsification with toric intraocular lens (IOL) implantation and Group 2 patients underwent phacoemulsification with monofocal IOL implantation followed by PRK 3 months later.

MAIN OUTCOME MEASURES

The main outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), residual cylinder, contrast sensitivity, glare acuity, pain score, and higher-order aberrations.

RESULTS

At 6 months 53.3% of eyes in the toric IOL and 60% eyes in the monofocal IOL with PRK group attained UDVA of 20/20. Median residual refractive cylinder value was higher in the toric IOL group (toric IOL = -0.5, monofocal IOL with PRK = 0; P = .02). Mean root mean square value of total aberrations (5 mm pupil) was higher in monofocal IOL with PRK eyes (toric IOL= 1.02 ± 0.44, monofocal IOL with PRK = 1.28 ± 0.5; P = .04). Mean contrast sensitivity values were comparable. Mean toric IOL rotation was 1.3 ± 2.1 degrees. Mean glare acuity was better in toric IOL eyes (toric IOL = 0.46 ± 0.16, monofocal IOL with PRK = 0.73 ± 0.12; P < .001). Median postoperative pain scores were higher in monofocal IOL with PRK eyes.

CONCLUSION

PRK yields lesser residual cylinder compared to toric IOL. However, it causes greater postoperative pain and corneal aberrations, and poor glare acuity.

Vector Analysis of Corneal Astigmatism After Combined Femtosecond-Assisted Phacoemulsification and Arcuate Keratotomy

PURPOSE

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

DESIGN

Retrospective, interventional case series.

METHODS

This study included patients who underwent combined femtosecond-assisted phacoemulsification and arcuate keratotomy between March 2013 and August 2013. Keratometric astigmatism was evaluated before and 2 months after the surgery. Vector analysis of the astigmatic changes was performed using the Alpins method.

RESULTS

Overall, 54 eyes of 54 patients (18 male and 36 female; mean age, 68.8 ± 11.4 years) were included. The mean preoperative (target-induced astigmatism) and postoperative astigmatism was 1.33 ± 0.57 diopters (D) and 0.87 ± 0.56 D, respectively (P < .001). The magnitude of error (difference between surgically induced and target-induced astigmatism) (-0.13 ± 0.68 D), as well as the correction index (ratio of surgically induced and target-induced astigmatism) (0.86 ± 0.52), demonstrated slight undercorrection. The angle of error was very close to 0, indicating no significant systematic error of misaligned treatment. However, the absolute angle of error showed a less favorable range (17.5 ± 19.2 degrees), suggesting variable factors such as healing or alignment at an individual level. There were no intraoperative or postoperative complications.

CONCLUSIONS

Combined phacoemulsification with arcuate keratotomy using femtosecond laser appears to be a relatively easy and safe means for management of low to moderate corneal astigmatism in cataract surgery candidates. Misalignment at an individual level can reduce its effectiveness. This issue remains to be elucidated in future studies.

Comparative evaluation of aspheric toric intraocular lens implantation and limbal relaxing incisions in eyes with cataracts and ≤3 dioptres of astigmatism

PURPOSE

To compare the visual outcomes of aspheric toric intraocular lens (IOL) implantation and limbal relaxing incisions (LRI) for management of coexisting age-related cataracts and astigmatism.

METHODS

In this prospective study, sixty eyes of 60 patients with visually significant cataract and coexisting corneal astigmatism ≤3 dioptres (D) were randomised to undergo phacoemulsification with either aspheric toric IOL or aspheric monofocal IOL with LRI. The main outcome measures were postoperative 3-month uncorrected visual acuity (UCVA), contrast sensitivity, rotational stability of the toric IOL and spectacle independence.

RESULTS

The postoperative UCVA, contrast sensitivity and refractive astigmatism were significantly better than the baseline measurements for both groups (p≤0.001). There was no significant difference detected for these parameters between LRI and toric IOL groups postoperatively (p≥0.119). At both postoperative month 1 and 3, the percentages of eyes in need of spectacles were lower in toric group than LRI group (p≤0.030). IOL misalignment was noted in three eyes in the toric IOL group (mean misalignment 7.67±4.04°). On vector analysis, magnitude of error (ME) was negative in the LRI group indicating undercorrection, whereas the ME was close to zero for toric group.

CONCLUSIONS

Both toric IOL implantation and LRI were effective in correcting corneal astigmatism ≤3 D during phacoemulsification, while LRI tended to undercorrect astigmatism.

Clinical utility of femtosecond laser-assisted astigmatic keratotomy after cataract surgery

PURPOSE

To examine the clinical utility of femtosecond laser-assisted astigmatic keratotomy (FSL-AK) for eyes after cataract surgery.

METHODS

Eight eyes of 6 patients with an intraocular lens and corneal astigmatism of 2.0 diopters (D) or more underwent FSL-AK. The mean preoperative manifest cylindrical refraction was 2.88 ± 0.64 D and the mean corneal astigmatism was 2.84 ± 0.83 D. Paired symmetrical arcuate incisions were created with the same settings, except for the incision depth. Uncorrected distance visual acuity (UDVA), manifest cylindrical power, and surgically induced astigmatism (SIA) were measured at 1 day, 1 week, and 1 month postoperatively. Fourier analysis of corneal topography and incision depths measured with anterior-segment optical coherence tomography were evaluated 1 month postoperatively.

RESULTS

In all eyes, the UDVA improved at 1 week and 1 month postoperatively, and the manifest cylinder also decreased postoperatively, while the SIA showed overcorrections in 6 eyes. Fourier analysis showed decreases in spherical and regular astigmatic components and increases in higher-order irregularity. The mean incision depth was measured as 60 µm deeper than the intended depth.

CONCLUSION

The FSL-AK effectively reduced corneal astigmatism and improved the UDVA, although it was demonstrated that the deeper incisions led to overcorrection.

Corneal astigmatism change and wavefront aberration evaluation after cataract surgery: "Single" versus "paired opposite" clear corneal incisions

Background:

Correcting the pre-existing astigmatism is an optimal goal in cataract surgery. The aim of this study is to compare the astigmatic correcting effect of a single regular 3.2 mm clear corneal incision (CCI) with paired opposite CCI in cataract patients and effect of these incisions on optical aberrations using the wavefront quantitative analysis.

Materials and Methods:

This was a randomized controlled trial study undertaken in an ophthalmology referral center on 50 patients planned for cataract surgery who were randomized to either single 3.2 mm CCI or paired opposite CCI group. Post-operative evaluation was performed at 12 weeks and included refraction, keratometery, corneal topography and wavefront analysis. Corneal astigmatism and post-operative values were compared in two groups.

Results:

The mean pre-operative corneal astigmatism was 2.58 ± 1.03 D in the single incision group and 2.70 ± 0.94 D in the paired opposite incisions group. After 12 weeks of surgery, the corneal astigmatism was reached to 2.15 ± 0.82 D in single incision group and 1.63 ± 1.21 in the paired opposite incisions group. There was a statistically significant difference in two arms of treatment regarding to surgically induced astigmatism after 3 months. The mean post-operative total and higher order aberrations and values were not significantly different in two groups.

Conclusion:

The results of our study showed that paired opposite incisions is an effective procedure for reducing pre-existing corneal astigmatism in cataract surgery. Paired incisions did not show any beneficial effect regarding wavefront aberrations compared with conventional single incision method.

Visual outcome and rotational stability of open loop toric intraocular lens implantation in Indian eyes

PURPOSE

To assess the visual outcome and rotational stability of single-piece open loop toric Intra Ocular Lens (IOL) in a clinical setting.

MATERIALS AND METHODS

In a prospective study, 122 eyes of 77 patients were followed up for a period of 12 months after cataract surgery with toric open loop IOL implantation. The pre-operative markings for the position of incision and IOL placement were done under slit lamp by anterior stromal puncture. The visual acuity, refraction, and IOL position were assessed at day 1, 1 week, 1 month, 3 months, 6 months, and 12 months after surgery.

RESULTS

The mean age of the cohort was 56 yrs (S.D. 13.88; range 16 to 87 years). The mean pre-operative cylinder of corneal astigmatism was 1.37 D. (SD 0.79, range 1.0 to 5.87 D). Mean post-operative refractive cylinder was 0.36 D (SD 0.57, range 0 to 1.50 D) at 12 months. Ninety-seven percent of the eyes were within 1 D of residual astigmatism. Ninety-four percent of patients had uncorrected visual acuity of 20/30 or better. Four eyes required IOL repositioning due to rotation. At 12 months, 96.7% of the IOLs were within 10 degrees of the target axis. There was no rotation seen after 6 months.

CONCLUSION

Toric IOLs are very effective and consistent in correcting astigmatism during the cataract surgery. IOL rotation happens mostly within a month of surgery, and if significant, requires early repositioning.

Toric intraocular lens implantation versus astigmatic keratotomy to correct astigmatism during phacoemulsification

PURPOSE

To compare toric intraocular lens (IOL) implantation and astigmatic keratotomy (AK) in correction of astigmatism during phacoemulsification.

SETTING

Tertiary care hospital.

DESIGN

Prospective randomized trial.

METHODS

Consecutive patients with visually significant cataract and moderate astigmatism (1.25 to 3.00 diopters [D]) were randomized into 2 groups. Temporal clear corneal 2.75 mm phacoemulsification with toric IOL implantation was performed in the toric IOL group and with 30-degree coupled AK at the 7.0 mm optic zone in the keratotomy group. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, keratometry, topography, central corneal thickness, and endothelial cell density were evaluated preoperatively and 1 day, 1 week, and 1 and 3 months postoperatively.

RESULTS

The study enrolled 34 eyes (34 patients), 17 in each group. There was no difference in UDVA or CDVA between the 2 groups at any follow-up visit. The mean preoperative and postoperative refractive cylinder was 2.00 D ± 0.49 (SD) and 0.33 ± 0.17 D, respectively, in the toric IOL group and 1.95 ± 0.47 D and 0.57 ± 0.41 D, respectively, in the keratotomy group (P=.10). The mean residual astigmatism at 3 months was 0.44 ± 1.89 @ 160 in the toric IOL group and 0.77 ± 1.92 @ 174 in the keratotomy group (P=.61). All eyes in the toric IOL group and 14 eyes (84%) in the keratotomy group achieved a residual refractive cylinder of 1.00 D or less (P=.17).

CONCLUSION

Toric IOL implantation was comparable to AK in eyes with moderate astigmatism having phacoemulsification.

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

PURPOSE

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

DESIGN

A retrospective comparison study.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Corneal astigmatism correction with scleral flaps in trans-scleral suture-fixed posterior chamber lens implantation: a preliminary clinical observation

AIM

To study the impact of scleral flap position, under which the posterior chamber intraocular lenses (PC-IOL) were sulcus-fixed by trans-scleral suture, on cornea astigmatism.

METHODS

Twenty-six aphakic or cataract eyes were comprised in this prospective noncomparative case series study. Eleven eyes had traumatic cataract removed without sufficient capsular support, 3 had blunt trauma with subluxated traumatic cataract, 8 had undergone vitreoretinal surgery and 4 had congenital cataract removed. The average age was 54 years (range 21-74 years), with 17 men and 7 women. The foldable PC-IOL was fixed in sulcus by trans-scleral suture. The incision for IOL implantation was made 1mm posterior to limbus along the steepest meridian of cornea, while scleral flaps to bury the knots of trans-scleral suture were made along the flattest meridian. All the surgeries were performed by a single doctor (Ma L), and the follow up was at least 13 months (range 13-28 months). The preoperative, 3 months and 1 year postoperative corneal curvature along the steepest and flattest cornea meridian and overall cornea astigmatism were compared.

RESULTS

The curvature along the steepest meridian changed from 44.25±2.22D preoperatively to 44.08±2.16D at 3 months postoperatively, and 43.65±5.23D at 1 year postoperatively (P>0.05); the curvature along the flattest meridian changed from 41.24±2.21D preoperatively to 43.15±3.94D at 3 months postoperatively, and 42.85±5.17D at 1 year postoperatively (P<0.05); and the surgery induced astigmatism (SIA) on cornea was calculated by vector analysis, which was 2.42±2.13D at 3 months postoperatively, and 2.18±3.42D at 1 year postoperatively, the difference was statistically significant (P<0.05).

CONCLUSION

The scleral flap made along the flattest meridian, under which the posterior chamber intraocular lenses (PCIOL) were sulcus-fixed by trans-scleral suture, can steepen the cornea in varying degrees, thus reducing preexisting corneal astigmatism.

The effect of corneal anterior surface eccentricity on astigmatism after cataract surgery

BACKGROUND AND OBJECTIVE

To evaluate the effect of cornea eccentricity on induced astigmatism after cataract surgery.

PATIENTS AND METHODS

The study included 125 eyes of 87 patients. Preoperative corneal astigmatism, pachymetry, and eccentricity were measured. During cataract surgery, the location of the main incision (2.8-mm clear corneal) was selected to be either superior, superior-nasal, superior-temporal, nasal, or temporal to decrease the preexisting corneal astigmatism. Aspheric intraocular lenses were implanted. Keratometry and manifest refraction were recorded 6 months after surgery. Astigmatism was calculated using vector subtraction software.

RESULTS

Three parameters significantly affected postoperative astigmatism: preoperative amount of corneal astigmatism, eccentricity of anterior cornea, and location of the main incision. The mean surgically induced astigmatism (SIA) was calculated to be: superior = 0.82 diopters (D), superior-nasal = 0.50 D, superior-temporal = 0.63 D, temporal = 0.45 D, and nasal = 0.55 D. Superior incision induced the greatest SIA and temporal incision induced the smallest SIA. The eccentricity of anterior cornea showed significantly positive correlation with the amount of SIA (P < .001). The preoperative corneal cylinder power showed significantly positive correlation with the amount of SIA (P < .001).

CONCLUSION

Postoperative astigmatism was affected by various factors in cataract surgery. The greatest postoperative astigmatism is expected in corneas with high anterior eccentricity, high preoperative corneal astigmatism, and superior location of the main incision.

Acrylic toric intraocular lens implantation: a single center experience concerning clinical outcomes and postoperative rotation

Purpose:

To present clinical results of toric intraocular lens (IOL) implantation for preexisting astigmatism correction and determine the time of any postoperative rotation.

Patients and methods:

Twenty-nine eyes of 19 patients underwent uncomplicated phacoemulsification and were implanted with an Acrysof ^© toric IOL. Uncorrected visual acuity, residual astigmatism, and postoperative rotation of the IOL were estimated one and six months after the operation.

Results:

Uncorrected visual acuity was ≥0.5 in 26 of 29 eyes (89.7%) and ≥0.8 in 19 of 29 patients (65.5%). The mean toric IOL axis rotation was 2.2 ± 1.5° (range 0.6–7.8°) one month postoperation and 2.7 ± 1.5° (range 0.9–8.4°) six months postoperation.

Conclusion:

Implantation of one-piece hydrophobic acrylic toric IOLs appears to have acceptable stability, which encourages visual outcome and emerges as an attractive alternative for correction of refractive astigmatism.

Corneal astigmatism correction with opposite clear corneal incisions or single clear corneal incision: Comparative analysis

PURPOSE

To compare the astigmatic correcting effect of paired opposite clear corneal incisions (OCCIs) on the steep axis with that of single clear corneal incisions (CCIs) in cataract patients having phacoemulsification.

SETTING

Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India.

METHODS

This randomized prospective clinical study comprised 40 eyes of 40 patients with topographic astigmatism of more than 1.50 diopters (D). Paired 3.2 mm OCCIs were made in the steep axis in Group 1 and single CCIs in Group 2. Preoperative evaluation included uncorrected visual acuity, refraction, applanation tonometry, dilated fundoscopy, biomicroscopic examination, keratometry, and topography. The steep axis was marked before sub-Tenon's anesthesia was given and routine phacoemulsification was performed through a 3.2 mm CCI on the steep axis. An additional opposite 3-step self-sealing CCI was made in Group 1. Patients were examined 1, 4, and 12 weeks postoperatively. Visual acuity, refraction, keratometry, and topography were evaluated.

RESULTS

The mean preoperative and postoperative topographic corneal astigmatism was 2.51 D +/- 0.92 (SD) and 0.91 +/- 0.54 D, respectively, in Group 1 and 2.16 +/- 0.80 D and 1.57 +/- 0.70 D, respectively, in Group 2. Mean astigmatic correction was 1.66 +/- 0.5 D and 0.85 +/- 0.75 D in Group 1 and Group 2, respectively. Mean surgically induced astigmatism, measured by a vector-corrected method, was 1.66 +/- 0.50 D and 0.85 +/- 0.75 D in Group 1 and Group 2, respectively (P = .00). The coupling ratio was -0.96 in Group 1 and -0.87 in Group 2. The spherical equivalent was +0.23 +/- 0.41 D in Group 1 and +0.11 +/- 0.17 D in Group 2 at 12 weeks. Uncorrected visual acuity was better in Group 1 than in Group 2 (P = .032). There was no difference in best corrected visual acuity between the groups. There were no incision-related complications.

CONCLUSION

Paired OCCIs were predictable and effective in providing an enhanced effect for correcting preexisting corneal astigmatism in cataract surgery.

Evaluation of a toric intraocular lens with a Z-haptic

PURPOSE

To evaluate the efficacy and rotational stability of the MicroSil 6116TU foldable 3-piece silicone toric intraocular lens (IOL) (HumanOptics).

SETTING

Department of Ophthalmology, Hillingdon Hospital, Uxbridge, Middlesex, United Kingdom.

METHODS

This prospective observational study included 21 eyes of 14 consecutive patients with more than 1.50 diopters (D) of preexisting corneal astigmatism having cataract surgery. Phacoemulsification was performed, and a MicroSil 6116TU toric IOL was inserted through a 3.4 mm temporal corneal incision. LogMAR uncorrected visual acuity (UCVA), best corrected visual acuity, refraction, keratometry, and cylinder axis of the toric IOL were measured.

RESULTS

The mean preoperative refractive and keratometric astigmatism was 3.52 D +/- 1.11 (SD) and 3.08 +/- 0.76 D, respectively. Six months postoperatively, the logMAR UCVA in eyes without ocular comorbidity (n = 14) was 0.20 +/- 0.15 (Snellen 20/32). Seventy-nine percent (11 eyes) had a visual acuity of 0.24 (Snellen 20/35) or better. The mean refractive astigmatism at 6 months was 1.23 +/- 0.90 D. Vector analysis using the Holladay-Cravy-Koch method showed a mean reduction in refractive astigmatism of 2.16 +/- 2.33 D. The mean difference between intended and achieved cylinder axis at 6 months was 5.2 degrees (range 0 to 15 degrees). No IOL rotated more than 5 degrees during the follow-up period.

CONCLUSIONS

The MicroSil 6116TU toric IOL reduced visually significant keratometric astigmatism and increased spectacle independence. The IOL was stable in the capsular bag, showing no significant rotation up to 6 months postoperatively.

Paired opposite clear corneal incisions to correct preexisting astigmatism in cataract patients

PURPOSE

To evaluate the astigmatic correcting effect of paired opposite clear corneal incisions on steep axis in cataract patients.

SETTING

Sligo General Hospital, Sligo, Ireland.

METHODS

Fifteen eyes of 14 cataract patients with a mean age of 78.4 years +/- 6.38 (SD) (range 69 to 90 years) were recruited for the study. Inclusion criterion was topographic astigmatism of more than 2 diopters (D) in the cataractous eye. Preoperative refraction, autokeratometry, and topography were performed. The steep axis was marked before sub-Tenon's anesthesia was given. Paired 3-step self-sealing opposite clear corneal incisions were made 1 mm anterior to limbus on the steep axis with a 3.2 mm keratome. One incision was used for standard phacoemulsification, and the other was left unused for astigmatic correction. All the patients had day-case surgery. The first follow-up was at 1 month. Postoperative topography, keratometry, and refraction were performed on all patients.

RESULTS

Mean preoperative and postoperative topographic corneal astigmatism were 3.26 +/- 1.03 D (range 2.30 to 5.80 D) and 2.02 +/- 1.04 D (range 0.20 to 4.00 D), respectively. Mean astigmatic correction was 1.23 +/- 0.49 D (range 0.30 to 2.20 D). Mean surgically induced astigmatism by vector analysis was 2.10 +/- 0.79 D (range 0.80 to 3.36 D). There were no incision-related complications.

CONCLUSION

Paired opposite clear corneal incisions on the steep axis is a useful way to correct astigmatism in cataract patients, requiring no extra skill or instrumentation.

Linear–long incisions with a small optical zone for the correction of astigmatism in older patients

PURPOSE

To evaluate the efficacy of astigmatic keratotomy (AK) by paired linear (transverse)-long incisions within a small optical zone in older patients with 3.00 diopters (D) or more of astigmatism who are intolerant of contact lenses, spectacles, or both.

DESIGN

Prospective, noncomparative case series.

PARTICIPANTS

Twenty-one eyes (20 patients; age range, 58-87 years) treated at clinics of the Taipei Veterans General Hospital were included in this study.

METHODS

Paired linear incisions (90 degrees in length) with a central optical zone (OZ) of 4.5 mm were made to correct high astigmatism in older patients. The incisions were 80% of the corneal thickness and parallel to the axis of the steepest cylinder.

MAIN OUTCOME MEASURES

Refraction, keratometry, corneal topography, and visual acuity with and without correction were measured as the outcome indicators.

RESULTS

The mean course of the stabilization of corneal curvature was 1.8 months. Significant improvement from a preoperative corneal astigmatism of 4.52+/-1.39 D to a postoperative value of 1.82+/-0.88 D (P<0.0001) was shown. Marked axis deviations of more than 30 degrees were observed in 5 cases and corneal perforation was observed in 1 case. When the corneal curvature stabilized, uncorrected visual acuity was improved by 2 lines or more in 15 eyes (71.4%). Spherical equivalents and best-corrected visual acuity did not change significantly. Postoperative glare was absent in all patients.

CONCLUSIONS

We conclude that AK by linear-long incisions extending from a small OZ is effective and safe for correcting astigmatism.

Treating astigmatism at the time of cataract surgery

An increasingly important goal of modern cataract and implant surgery is to obtain the most desirable refractive outcome for our patients, and in so doing, decrease their dependence upon spectacle correction. Refined spherical outcomes are now achieved by directing close attention to biometry technique, through the use of third generation intraocular lens (IOL) power formulae, and refinements in technology such as partial coherence interferometry. Similarly, improvements in astigmatic outcomes are now possible by focusing upon and obtaining more accurate preoperative cylinder measurements, careful surgical planning particularly in regard to incision(s) design, use of toric IOLs, and employing advanced postoperative enhancement techniques. Because of these refinements in technique and technology, the field of cataract and implant surgery has emerged as a true and recognized form of refractive surgery.

Incisional refractive surgery

The use of incisional refractive surgery has become limited due to the widespread use of the excimer laser to correct myopia, hyperopia and astigmatism. Laser in situ keratomileusis and photorefractive keratectomy have proven to be much more accurate and predictable in correcting refractive error. This has made some forms of incisional refractive surgery practically obsolete. Radial keratotomy should not be considered a primary refractive procedure in the modern world, as RK has become "RKhaic". There are still indications for incisional refractive surgery in cataract and post-surgical patients for the treatment of astigmatism. However, with the advent of the toric intraocular lens and the use of LASIK in such aforementioned patients, these indications for incisional surgery will likely become more limited. In this review, we go over the past history of incisional refractive surgery and also report the current uses and advancements of this technique in today's practice environment.