Intraindividual comparative study of corneal and ocular wavefront aberrations after biaxial microincision versus coaxial small-incision cataract surgery

Effect of cataract incision type on corneal spherical aberration

Corneal spherical aberration (CSA) plays an important role in the ocular refractive system. However, ophthalmologists have not considered the effect of difference cataract incisions on it. The purpose of this study is to investigate the effect of transparent corneal incision (TCI) and scleral tunnel incision (STI) on CSA after the cataract phacoemulsification with foldable IOLs. One hundred ninety-three eyes (61 males and 79 females) for 1-month observation and 114 eyes (29 males and 51 females) for 3-month observation with age-related cataracts (ARC) were included in this study. CSA was measured with dilated pupil by Pentacam Scheimpflug system at 1 day preoperative and 1, 3-month postoperative. Preoperative CSA >1.00 μm was excluded. Both TCI and STI are 3 mm incisions with Infiniti system and Ozil handpiece. No significant difference of age or gender was found between TCI and STI groups in 1 or 3-month observation. In 1-month observation, preoperative CSA for TCI and STI are 0.31 ± 0.29 and 0.41 ± 0.19 μm, which of postoperative are 0.42 ± 0.17 and 0.44 ± 0.35 μm, respectively. The change of CSA is 0.11 ± 0.32 and 0.04 ± 0.33 μm (P = .233). For 3-month observation, preoperative CSA for TCI and STI are 0.32 ± 0.28 and 0.36 ± 0.23 μm, which of postoperative are 0.43 ± 0.16 and 0.39 ± 0.26 μm, respectively. The change of CSA is 0.10 ± 0.34 and 0.03 ± 0.21 μm (P = .312). For the phacoemulsification combined with foldable IOL implantation, STI has minimal effect on CSA, but TCI might increase postoperative CSA.

The impact of limbus detection, arcus lipoides and limbal vessels on the primary patency of clear cornea incisions in femtosecond laser-assisted cataract surgery

PURPOSE

To analyse the factors influencing the primary patency of clear corneal incisions in femtosecond laser-assisted cataract surgery (FLACS).

METHODS

In this prospective single-centre study, the graphical user interfaces of 159 patients undergoing femtosecond laser-assisted cataract surgery were documented by video. Subsequently, the quality of limbus detection along with the incidence of vessels and an arcus lipoides were assessed by a grading system and analysed in relation to the primary patency of the incisions. In particular, the differences between a superior and a temporal main incision were analysed.

RESULTS

The designed grading system could be applied in all cases without any problems. Limbus detection was highly inhomogeneous but had no influence on the patency of the incisions (46.3% poor, 18.4% moderate, 35.1% good). The characteristics of the arcus lipoides had little influence on the patency of the main incisions. Pronounced vascular ingrowth caused more tissue bridges but did not reduce the patency of the incisions. Temporal access was generally easier to open than a superior one (97.1% versus 88.9%).

CONCLUSION

We showed a patency rate of superior FLACS incisions of over 97% with the Femto LDV Z8 in our study. Temporal main incision is preferable to superior main incision in more difficult situations. The new grading system is suitable for further studies to provide information on the quality of the incision.

Corneal higher-order aberrations after cataract surgery: Manual phacoemulsification versus femtosecond-laser assisted technique

Purpose:

To compare and evaluate corneal higher-order aberrations (c-HOA) between conventional manual phacoemulsification (Phaco), femtosecond laser-assisted cataract surgery (FLACS), and femtosecond laser-assisted cataract surgery with astigmatic keratotomy (FSAK).

Methods:

In this retrospective single center study, 53 healthy individuals with cataract (73 eyes) underwent phacoemulsification with implantation of an intraocular lens. Three groups were formed: group A, Phaco (n = 27 eyes of 21 patients); group B, FLACS (n = 25 eyes of 15 patients); group C, FSAK (n = 21 eyes of 17 patients). An iTrace aberrometer (Tracey Technologies, Houston, TX, USA) was used to perform aberrometry with a pupil scan size of 5.0 mm. We used ANOVA analysis and the paired sample t-test for statistical analysis.

Results:

There was no difference in total c-HOA between the groups prior to surgery (F(2,66) = 2.2, p = 0.128), but some evidence for a difference between the groups after surgery (F(2,65) = 3.87, p = 0.025). After surgery, total c-HOA increased in all groups, but the greatest increase occurred FSAK.

Conclusion:

Manual phacoemulsification and femtosecond laser-assisted cataract surgery seem to have less impact on corneal higher-order aberrations than the combination of femtosecond laser-assisted cataract surgery with astigmatic keratotomy.

Evaluation of clinical outcomes following implantation of a sub-2-mm hydrophilic acrylic MICS intraocular lens

PURPOSE

To evaluate clinical outcomes following sub-2-mm microincision cataract surgery (MICS) and intraocular lens (IOL) implantation.

SETTING

Five EU clinical sites.

DESIGN

Prospective, multicenter, open-label, single-arm, non-randomized.

METHODS

Preoperative assessment involved visual acuity (VA), intraocular pressure and biometry measurements. 1.4-mm wound-assisted or 1.8-mm MICS was performed. Follow-up visits were made 1 day, 1-2 weeks, 1-2 and 4-6 months after surgery. The incision size, corrected distance VA (CDVA), uncorrected distance VA, manifest refraction spherical equivalent (MRSE), refraction predictability/stability and IOL decentration were assessed. At 12-, 18-, and 24-month, long-term centration, posterior capsular opacification (PCO) and Nd:YAG capsulotomy rates were investigated.

RESULTS

A total of 103 eyes were implanted with the study IOL (INCISE, Bausch & Lomb), 96 of which were included in visual outcome analysis. A mean 6-month CDVA of - 0.02 logMAR (20/20 + 1) was observed and 75 eyes (79.8%) and 93 eyes (98.3%) achieved a visual acuity of at least 20/20 or 20/40. Mean MRSE was - 0.20 ± 0.60 D. Mean absolute predictive error was 0.44 ± 0.36 D, with 90.4% within 1.00 D of target. Mean total decentration was 0.35 ± 0.36 mm at 6 months and 0.32 ± 0.14 mm at 24 months (p > 0.05). 24-month evaluation of posterior capsular opacification score was 0.03 for the central area. A Nd:YAG rate of 3.4% was observed at 24 months.

CONCLUSIONS

The new MICS IOL provided excellent visual outcomes and was safe and effective for the sub-2-mm procedure. The MICS IOL demonstrated long-term centration, stability and a low rate of PCO development.

Different-sized incisions for phacoemulsification in age-related cataract

BACKGROUND

Age-related cataract is the principal cause of blindness and visual impairment in the world. Phacoemulsification is the main surgical procedure used to treat cataract. The comparative effectiveness and safety of different-sized incisions for phacoemulsification has not been determined.

OBJECTIVES

The aim of this systematic review was to assess the effectiveness and safety of smaller versus larger incisions for phacoemulsification in age-related cataract. The primary outcome of this review was surgically induced astigmatism at three months after surgery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 10), MEDLINE Ovid (1946 to 28 October 2016), Embase Ovid (1947 to 28 October 2016), PubMed (1948 to 28 October 2016), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 28 October 2016), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com; last searched 13 May 2013), ClinicalTrials.gov (www.clinicaltrials.gov; searched 28 October 2016), and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp; searched 28 October 2016). We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing different-sized incisions in people with age-related cataract undergoing phacoemulsification.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 26 RCTs with a total of 2737 participants (3120 eyes). These trials were conducted in Bosnia and Herzegovina, China, France, India, Italy, Korea, Spain, Switzerland, and Turkey. Half of the 26 trials were conducted in China. We judged all trials as mostly at unclear to low risk of bias. The included RCTs compared four different-sized incisions:<= 1.5 mm, 1.8 mm, 2.2 mm, and approximately 3.0 mm. These incisions were performed using three different techniques: coaxial and biaxial microincision phacoemulsification (C-MICS and B-MICS) and standard phacoemulsification. Not all studies provided data in a form that could be included in this review. Five studies had three arms.Fifteen trials compared C-MICS (2.2 mm) with standard phacoemulsification (about 3.0 mm). Very low-certainty evidence suggested less surgically induced astigmatism in the C-MICS group at three months compared with standard phacoemulsification (mean difference (MD) -0.19 diopters (D), 95% confidence interval (CI) -0.30 to -0.09; 996 eyes; 8 RCTs). There was low-certainty evidence that both groups achieved similar best-corrected visual acuity (MD 0.00 logMAR, 95% CI -0.02 to 0.02; 242 eyes; 3 RCTs). There was low-certainty evidence of little or no difference in endothelial cell loss and central corneal thickness comparing C-MICS with standard phacoemulsification (MD -7.23 cells/mm², 95% CI -78.66 to 64.20; 596 eyes; 4 RCTs) and (MD -0.68 μm, 95% CI -3.26 to 1.90; 487 eyes; 5 RCTs).Nine trials compared C-MICS (1.8 mm) with standard phacoemulsification (about 3.0 mm). Very low-certainty evidence suggested less astigmatism at three months in the C-MICS group compared with standard phacoemulsification group (MD -0.23 D, 95% CI -0.34 to -0.13; 561 eyes; 5 RCTs). Low-certainty evidence suggested little or no difference in best-corrected visual acuity, endothelial cell loss, and central corneal thickness in the two groups at three months (MD -0.02 logMAR, 95% CI -0.03 to -0.00; 192 eyes; 3 RCTs), (MD 7.56 cells/mm², 95% CI -67.65 to 82.77; 380 eyes; 5 RCTs), and (MD -1.52 μm, 95% CI -6.29 to 3.25; 245 eyes; 3 RCTs).Six studies compared C-MICS (1.8 mm) with C-MICS (2.2 mm). There was low-certainty evidence that astigmatism, visual acuity, and central corneal thickness were similar in the two groups at three months (MD 0.04 D, 95% CI -0.09 to 0.16; 259 eyes; 3 RCTs), (MD 0.01 logMAR, 95% CI -0.01 to 0.04; 200 eyes; 3 RCTs), and (MD 0.45 μm, 95% CI -2.70 to 3.60; 100 eyes; 1 RCT). Very low-certainty evidence suggested higher endothelial cell loss in the 1.8 mm group (MD 213.00 cells/mm², 95% CI 11.15 to 414.85; 70 eyes; 1 RCT).Four studies compared B-MICS (<= 1.5 mm) with standard phacoemulsification (about 3.0 mm). Astigmatism was similar in the two groups at three months (MD -0.01 D, 95% CI -0.03 to 0.01; 368 eyes; 2 RCTs; moderate-certainty evidence). There was low-certainty evidence on visual acuity, suggesting little or no difference between the two groups (MD -0.02 logMAR, 95% CI -0.04 to -0.00; 464 eyes; 3 RCTs). Low-certainty evidence on endothelial cell loss and central corneal thickness also suggested little or no difference between the two groups (MD 55.83 cells/mm², 95% CI -34.93 to 146.59; 280 eyes; 1 RCT) and (MD 0.10 μm, 95% CI -14.04 to 14.24; 90 eyes; 1 RCT).None of the trials reported on quality of life. One trial reported that no participants experienced endophthalmitis or posterior capsule rupture; they also reported little or no difference between incision groups regarding corneal edema (risk ratio 1.02, 95% CI 0.40 to 2.63; 362 eyes).

AUTHORS' CONCLUSIONS

Phacoemulsification with smaller incisions was not consistently associated with less surgically induced astigmatism compared with phacoemulsification with larger incisions. Coaxial microincision phacoemulsification may be associated with less astigmatism than standard phacoemulsification, but the difference was small, in the order of 0.2 D, and the evidence was uncertain. Safety outcomes and quality of life were not adequately reported; these should be addressed in future studies.

Corneal Higher-Order Aberrations after Phacoemulsification: A Comparison of 3 Different Incision Sizes

Purpose

To analyze the impact of different incision sizes for phacoemulsification on corneal higher-order aberrations (HOA).

Methods

Patients seeking cataract surgery were randomly assigned to one of the following groups: 1.4 mm with biaxial microincision phacoemulsification (25 eyes), 1.8 mm with coaxial phacoemulsification (27 eyes), and 2.2 mm with coaxial phacoemulsification (62 eyes). Inclusion criteria were a minimum age of 18 years and uncomplicated cataract. Exclusion criteria were history of ocular trauma or intraocular surgery, any sign of inflammation or infection, pseudoexfoliation syndrome, glaucoma, optic atrophy, diabetic retinopathy, lens dislocation, cataracta intumescens, cataracta matura, and corneal diseases. Patients underwent phacoemulsification with implantation of an intraocular lens. Aberrometry was performed using an iTrace aberrometer with a pupil scan size of 5.0 mm preoperatively and at postoperative follow-up visits after 1 month. The paired sample t test and analysis of covariance were used for statistical analysis.

Results

Ninety patients (114 eyes) were enrolled (mean age 73.7 ± 8.9 years). In all groups, an increase of total HOAs could be measured. The strongest increase was seen in the 2.2 mm group (mean difference 0.031 [95% confidence interval (CI) 0.006-0.056], p = 0.014) and in the 1.4 mm group (mean difference 0.035 [95% CI -0.007 to 0078], p = 0.097). No important difference was found in the 1.8 mm group.

Conclusions

The 2.2 mm and the 1.4 mm incisions seem to have a higher impact on corneal HOAs in comparison to the 1.8 mm incision.

Surgical and Functional Results of Hybrid 25-27-Gauge Vitrectomy Combined with Coaxial 2.2 mm Small Incision Cataract Surgery

Purpose. To investigate outcomes after coaxial 2.2 mm small incision cataract surgery combined with hybrid 25-27-gauge vitrectomy in eyes with vitreoretinal disease and age-related cataract. Methods. A single-center, retrospective case series study of 55 subjects (55 eyes) with a mean age of 70 years who underwent combined small incision phacoemulsification, intraocular lens (IOL) implantation, and hybrid 25-27-gauge vitrectomy during the 12-month period to December 2014. Intraoperative and postoperative complications and visual results were the main outcome measures. Results. The mean follow-up period was 6 months (range: 2–18 months). Intraoperative findings were 3 retinal breaks (5.5%). No cases required corneal or scleral suture or conversion to larger-gauge vitrectomy. Postoperative complications consisted of posterior capsule opacification (12.7%), elevated intraocular pressure >30 mmHg (1.8%), and fibrin reaction (5.5%). There were no cases of hypotony (<7 mmHg), IOL decentration, or postoperative endophthalmitis. Visual acuity (mean ± SD) improved from 0.52 ± 0.6 logMAR preoperatively to 0.22 ± 0.46 logMAR at final postoperative visit (P < 0.0001). Conclusion. Surgical and visual outcomes suggest hybrid 25-27-gauge vitrectomy combined with small incision phacoemulsification and IOL implantation is feasible, safe, and effective as a one-step surgical procedure for the management of vitreoretinal pathologies and concurrent cataract.

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.

Bimanual microincision versus standard coaxial small-incision cataract surgery: meta-analysis of randomized controlled trials

PURPOSE

This meta-analysis aimed to evaluate the outcomes of bimanual microincision cataract surgery (B-MICS) through a 1.2- to 1.5-mm incision versus standard coaxial small-incision cataract surgery (C-SICS) through a 2.8- to 3.2-mm incision.

METHODS

A comprehensive literature search was performed according to the Cochrane Collaboration methodology to identify randomized controlled clinical trials comparing B-MICS with standard C-SICS. Main outcome measures were mean surgical time, mean phacoemulsification power, effective phacoemulsification time, best-corrected visual acuity, surgically induced astigmatism (SIA), mean laser flare photometry values, mean endothelial cell loss, mean increased central corneal thickness, and intraoperative and postoperative complications.

RESULTS

We identified 14 randomized controlled clinical trials that included 1235 eyes diagnosed with cataracts. No statistically significant differences were detected between the 2 surgical procedures in terms of best-corrected visual acuity (p&gt;0.05), SIA at postoperative 1 month (p = 0.09), laser flare photometry values (p = 0.38), mean endothelial cell loss (p = 0.53), increased central corneal thickness at postoperative 1 month (p = 0.64) or 3 months (p = 0.88), intraoperative complications (p = 0.68), and postoperative complications (p = 0.30); however, statistically significant differences were apparent for mean surgical time (p&lt;0.00001), mean phacoemulsification power (p = 0.008), effective phacoemulsification time (p = 0.0009), SIA at postoperative 3 months (p = 0.02), and increased central corneal thickness at postoperative 1 day (p = 0.04).

CONCLUSIONS

The meta-analysis shows that the 2 techniques have similar outcomes in terms of final visual acuity and complications. Bimanual MICS has the advantage of less SIA and phaco time whereas C-SICS has the advantage of quicker surgery and less likelihood of early-onset corneal edema.

Comparative outcomes of bimanual MICS and 2.2-mm coaxial phacoemulsification assisted by femtosecond technology

PURPOSE

To compare the efficacy and safety outcomes of bimanual microincision cataract surgery (MICS) versus 2.2-mm coaxial phacoemulsification assisted by Femtosecond LenSx (Alcon-LenSx Inc., Aliso Viejo, CA).

METHODS

This prospective, randomized, observational, comparative case series comprised 50 cataractous eyes of 50 patients receiving femtosecond laser refractive lens surgery followed by a bimanual MICS technique with two 1-mm incisions (25 patients) (FemtoMICS group) and a coaxial phacoemulsification technique with a 1-mm paracentesis and a 2.2-mm principal incision (25 patients) (FemtoCoaxial group). The main outcomes measures were: ultrasound power, effective phacoemulsification time, postoperative spherical equivalent, higher-order aberrations (corneal and internal), corneal thickness, endothelial cell count, macular thickness, and complications during and after surgery. Both groups were absolutely comparable for all variables preoperatively.

RESULTS

Mean ultrasound power was 1.8% ± 0.9% for MICS and 14.7% ± 4.9% for 2.2-mm incisions (P < .001). Effective phacoemulsification time values for MICS and 2.2-mm incisions were 1.5 ± 0.9 and 4.5 ± 2.9 sec, respectively (P = .002). Mean postoperative spherical equivalent was −0.26 for FemtoMICS and −0.33 for FemtoCoaxial (P > .05). The efficacy index at 1 month postoperatively was 160.2% for FemtoMICS and 149% for FemtoCoaxial. No significant differences were found in corneal thickness, endothelial cell count, and macular thickness. Complications included posterior capsule rupture (4%) and anterior capsule rupture with no posterior capsule tear (4%) for FemtoMICS and bridges due to incomplete capsulorhexis (4%) for FemtoCoaxial.

CONCLUSIONS

MICS and coaxial phacoemulsification techniques assisted by the Femtosecond LenSx achieved excellent safety and efficient outcomes. The FemtoMICS technique was surgically and statistically more efficient than the FemtoCoaxial technique.

Preliminary Investigation of Corneal Wavefront Aberration following Femtosecond Laser Clear Corneal Incision for Cataract Surgery

Purpose

To investigate the early changes of the anterior corneal wavefront aberration (WA) following femtosecond laser clear corneal incision (FS-CCI) for cataract surgery.

Methods

Twenty consecutive patients (20 eyes) with cataract underwent phacoemulsification and were divided into 2 groups: the study group received a 2.75-mm FS-CCI using an iFS Intralase; the control group received a 2.75-mm manual CCI using disposable knives. High-order corneal WA was analyzed over 3.5- and 6.0-mm pupils and corneal astigmatism was evaluated using vector analysis pre-operatively, 1 week postoperatively, and 1 month postoperatively.

Results

At 1 month postoperatively, the mean surgically induced astigmatism (D) of the anterior cornea was 1.22 ± 0.60 at 144° and 1.04 D ± 0.64 at 90° in the study and control groups (p<0.05), respectively. Over 3.5-mm pupil, there were no changes of corneal high-order aberrations (p>0.05) following FS-CCI. Trefoil increased significantly (p<0.01) following manual CCI at 1 week postoperatively. Over 6.0-mm pupil, FS-CCI did not induce any statistically significant change in corneal WA during follow-up. One week after manual CCI, total root mean square–high order aberrations (p<0.01), spherical aberration (p<0.05), and trefoil (p<0.001) were statistically significantly higher than pre-operatively.

Conclusions

The CCI method was shown to influence changes in corneal WA during the first month postoperatively. The different changes of corneal high-order WA between the study and control groups may depend on the different CCI geometry. These preliminary data are valuable to improve understanding of FS-CCI design.

Microincision cataract surgery combined with vitrectomy: a case series

AIM

The objective of this study was to present the results of combined phacovitrectomy using 1.8 mm microincision cataract surgery (MICS) with special emphasis on the anterior segment complications in this group.

METHODS

Retrospective, single-centre case series involving consecutive patients undergoing phacovitrectomy in a single centre in the United Kingdom during a 6-month period.

RESULTS

A total of 52 eyes underwent combined MICS and pars plana vitrectomy. Intraoperative complications included posterior capsule rupture (n=2), minor iris trauma during phacoemulsification (n=1), iatrogenic retinal tears (n=2), and entry site break (n=1). Postoperatively two cases had significant inflammation, one of which resulted in 360° posterior synaechiea, iris bombe, and raised intraocular pressure. Other complications included mild posterior synaechiae (n=2), posterior capsular opacification (n=3), cystoid macular oedema (n=1), and hyphaema (n=1), which spontaneously resolved. There were no cases of intraocular lens decentration. Two patients who underwent surgery for retinal detachment repair subsequently redetached. Among those having surgery for macular hole, non-closure was seen in one patient and one patient developed a retinal detachment.

CONCLUSION

In conclusion, sub-2 mm MICS is a safe and effective technique in dealing with vitreoretinal disorders necessitating cataract surgery at the same time.

[Optical quality after 2.2mm microincisional cataract surgery with bimanual I/A in 154 eyes]

PURPOSE

A prospective study to analyze the effects of 2.2mm microincisional coaxial phacoemulsification with bimanual irrigation/aspiration on the optical quality of the cornea and whole eye.

METHODS

We compare two groups. Group A: 102 consecutive eyes undergoing this three-incision procedure and implanted with an Alcon® SN60WF IQ aspheric intraocular lens. Astigmatism, corneal and total asphericity, as well as H/B ratio were measured by OPD scann II, Nidek®, Japan, preoperatively (Day 0), 15 days postoperatively (Day 15) and 1 month postoperatively (M1). Group B: 52 eyes with corneal astigmatism greater than 1.25D, undergoing the same procedure but implanted with a Toric IOL (Alcon® Toric IQ SN6AT), followed in the same manner but with additional follow-up at 1 year.

RESULTS

Corneal surgically induced astigmatism (SIA) was essentially neutral: 0.065D ± 0.86 at Day 30 in group A, and 0.06D ± 0.34 at 1 month and -0.008D ± 0.4 at 12 months in group B. Corneal topographic astigmatism underwent a mean axis shift of 29.95° ± 27.6 in group A compared to 5.3° ± 3.7 in Group B, and remained stable at 1 year. Corneal asphericity did not change significantly between Day 0 and 30 in either group. H/B ratio increased significantly in both groups, with a gain of 22 % to 24 % after surgery.

CONCLUSIONS

This three-incision procedure does not degrade the optical quality of the cornea. Postoperative shift in the axis of astigmatism is only an issue in cases of low or asymmetric astigmatism and must be kept in mind for low-power toric IOL implantation.

A ray tracing approach to calculate toric intraocular lenses

PURPOSE

To quantify the precision of astigmatic correction in routine cataract surgery with toric intraocular lenses (IOLs) and to evaluate the predictability of keratometric and anterior/posterior topographic measurement for the improvement of the overall accuracy.

METHODS

Seventy-eight eyes of 56 patients were implanted with toric IOLs. Data acquired by the Lenstar optical biometer (Haag-Streit, Bern, Switzerland) and TMS5 topography (Tomey, Nagoya, Japan) were processed with the ray tracing software Okulix (Tedics, Dortmund, Germany) to predict the residual refraction. Four different inputs were examined: keratometry only, anterior topography, anterior and posterior topography/ tomography, and combination of keratometry only and anterior and posterior topography/tomography. Four weeks postoperatively, the spherical prediction error and the cylindrical prediction error (difference vector between predicted and achieved cylindrical refraction) were determined.

RESULTS

Mean absolute error of spherical prediction error was 0.27 diopter (D). Cylindrical prediction errors were 0.57 D (keratometry only), 0.56 D (anterior topography), 0.56 D (anterior and posterior topography/ tomography), and 0.50 D (combination of keratometry only and anterior and posterior topography/tomography). Differences between intraocular lens groups were statistically significant (Friedman test, P < .05).

CONCLUSION

The combination of keratometry and anterior and posterior topography/tomography of anterior and posterior surface yielded the best results for toric IOL power calculations.

Influence of corneal biomechanical properties on surgically induced astigmatism in cataract surgery

PURPOSE

To perform an overall follow-up of the morphologic, optical, and biomechanical properties of the cornea to determine new parameters influencing the refractive outcomes of cataract surgery.

DESIGN

Clinical study.

METHODS

Patients scheduled for cataract surgery were assessed for surgically induced corneal astigmatism (SIA) and higher-order aberrations, (HOAs) using a Scheimpflug rotating camera (Pentacam) together with corneal imaging by optical coherence tomography (Spectralis) and biomechanical analysis by the Ocular Response Analyzer preoperatively and 1, 7, and 30 days postoperatively. The central and peripheral corneal thicknesses; incision width, length, and architecture; corneal hysteresis (CH); and corneal resistance factor (CRF) were computed to identify new parameters influencing corneal optical changes that determine the final refractive result.

RESULTS

The study enrolled 40 patients (40 eyes). The SIA and HOAs were significantly lower after microincision surgery (≤ 2.2 mm) than after small-incision surgery (2.75 mm) (both P<.01). The CRF was significantly reduced with a direct corneal incision compared with a constructed incision (P<.01). Multivariate analysis showed that SIA was correlated not only with incision width (P<.05) but also with preoperative CH (P<.01). Corneal 3rd-order trefoil depended on incision width (P<.01).

CONCLUSIONS

In addition to the well-known influence of incision size on SIA, CH also modulates optical changes. The biomechanical features of the cornea should be taken into account preoperatively to better predict the refractive outcomes of cataract surgery.

[Refractive precision and objective quality of vision after toric lens implantation in cataract surgery]

PURPOSE

To study efficacy and predictability of toric IOL implantation for correction of preoperative corneal astigmatism by analysing spherocylindrical refractive precision and objective quality of vision.

PATIENTS AND METHODS

Prospective study of 13 eyes undergoing micro-incisional cataract surgery through a 1.8mm corneal incision with toric IOL implantation (Lentis L313T(®), Oculentis) to treat over one D of preoperative corneal astigmatism. Preoperative evaluation included keratometry, subjective refraction, and total and corneal aberrometry (KR-1(®), Topcon). Six months postoperatively, measurements included slit lamp photography, documenting IOL rotation, tilt or decentration, uncorrected visual acuity, best-corrected visual acuity and objective quality of vision measurement (OQAS(®) Visiometrics, Spain).

RESULTS

Postoperatively, mean uncorrected distance visual acuity was 8.33/10 ± 1.91 (0.09 ± 0.11 LogMar). Mean postoperative refractive sphere was 0.13 ± 0.73 diopters. Mean refractive astigmatism was -0.66 ± 0.56 diopters with corneal astigmatism of 2.17 ± 0.68 diopters. Mean IOL rotation was 4.4° ± 3.6° (range 0° to 10°).

DISCUSSION

Mean rotation of this IOL at 6 months was less than 5°, demonstrating stability of the optic within the capsular bag. Objective quality of vision measurements were consistent with subjective uncorrected visual acuity.

CONCLUSION

Implantation of the L313T(®) IOL is safe and effective for correction of corneal astigmatism in 1.8mm micro-incisional cataract surgery.

[Post-operative residual astigmatism after cataract surgery: Current surgical methods of treatment]

Residual astigmatism after cataract surgery can be corrected by three different techniques: classic limbal relaxing incisions, easy to perform but with limited precision; laser refractive surgery (PRK or Lasik), additionally allowing for correction of spherical equivalent; and more recently the use of a piggyback toric intraocular lens in the ciliary sulcus.

Wavefront analysis and Zernike polynomial decomposition for evaluation of corneal optical quality

Wavefront-guided excimer laser refractive surgery and new customized intraocular lens and contact lens designs are major clinical applications of corneal wavefront analysis. Other therapeutic applications include corneal disorders, conventional excimer laser refractive surgery, incisional techniques and cataract surgery, corneal transplantation, intrastromal corneal ring segment implantation, and crosslinking therapy. Basic data regarding corneal wavefront aberrations, such as distribution in the population and changes with aging, are essential for understanding the nature of each aberration and correcting it. Corneal aberrometry also improved our comprehension of the optical effects of the aforementioned topics while helping us assess the success of the procedures. Zernike polynomials are representations of the higher- and lower-order aberrations of the cornea, allowing a mathematical approach to their determination. Polynomials are used to model individual components of the wavefront in familiar terms. This article reviews the current knowledge of the wavefront aberrations of the human cornea and analyzes studies in the fields of anterior segment surgery and/or therapy, diseases, and optical quality in the context of this knowledge.

Comparison of corneal aberrations after biaxial microincision and microcoaxial cataract surgeries: a prospective study

PURPOSE

To compare the effects of biaxial microincision cataract surgery (B-MICS) and microcoaxial cataract surgery (C-MICS) techniques on corneal optical quality.

MATERIALS AND METHODS

In this prospective study, 40 eyes underwent B-MICS and 40 eyes C-MICS. Corneal aberrations were derived from conversion of the corneal elevation profile into corneal wavefront data with 6.0  mm aperture diameter using Zernike polynomials by corneal topography preoperatively and 1 month postoperatively. Both magnitude and axes of surgically induced corneal aberrations were calculated.

RESULTS

Mean final incision widths were 1.80 ± 0.09  mm and 1.89 ± 0.11  mm (p = 0.062) in B-MICS and C-MICS groups, respectively. There were no significant changes in total and higher order root mean square in both groups postoperatively. In B-MICS group, all aberration terms were similar, before and after surgery. However, vertical coma (p = 0.002), vertical trefoil (p < 0.001) and primary trefoil (p = 0.042) significantly increased postoperatively in the C-MICS group. Except surgically induced trefoil (p = 0.047), there was no significant difference in all surgically induced corneal aberrations between groups. The axes of the induced trefoil were found to be mostly related and close to the incision site in both groups which was more prominent in the C-MICS group.

CONCLUSIONS

Microincision cataract surgery techniques performed through sub-1.9  mm clear corneal incisions do not generally degrade optical quality of the cornea while only small amount of higher order aberrations seem to be induced with C-MICS technique.

Corneal Optical Quality Following Sub 1.8 mm Micro-Incision Cataract Surgery vs. 2.2 mm Mini-Incision Coaxial Phacoemulsification

Purpose:

To study and compare the effects of the micro-incision cataract surgery (MICS-sub 1.8 mm) and miniincision coaxial phacoemulsification (2.2 mm) on the optical quality of the cornea characterized in terms of corneal aberrations.

Materials and Methods:

Fifty eyes underwent MICS and 50 mini-incision phacoemulsification, by the same surgeon. Both types of cataract surgery were performed using low ultrasound power and through a clear corneal incision, placed on the steepest corneal meridian ranging from 1.6 to 1.8 in MICS (Group I) and from 2.12 to 2.3 mm in mini-incision coaxial phacoemulsification (Group II). Seidel and Zernike aberration coefficients and RMS values were obtained for a 6-mm pupil preoperatively and one month after surgery.

Results:

The corneal astigmatism did not show statistically significant changes in either of the two groups: (MICS: –0.73 ± 0.63, –0.65 ± 0.53 D, P = 0.25), (mini-incision phacoemulsification; –1.21 ± 1.52, –1.00 ± 1.19 D, P = 0.12). The total RMS remained unchanged after MICS (1.77 ± 1.7, 1.65 ± 1.3 μm, P = 0.18) and mini-incision phacoemulsification (2.00 ± 1.87, 2.09 ± 1.8 μm, P = 0.41). Statistically significant changes were found for coma (P = 0.004) and higher-order aberrations (P < 0.001), showing MICS significantly less changes in cornea.

Conclusions:

Both MICS and mini-incision phacoemulsification do not degrade the optical quality of the cornea. Both surgeries do not induce a modification of the corneal astigmatism, even in the axis. It seems that 2 mm is the limit around which no optical changes are induced by cataract surgery in the human cornea.

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.

Microcoaxial torsional cataract surgery 1.8 mm versus 2.2 mm: functional and morphological assessment

BACKGROUND AND OBJECTIVE

To compare functional and morphological outcomes of 1.8-mm versus 2.2-mm microincision coaxial cataract surgery (MCCS).

PATIENTS AND METHODS

Thirty eyes of 30 patients that underwent MCCS were randomized to two groups: 1.8-mm MCCS (group 1: 15 eyes) and 2.2-mm MCCS (group 2: 15 eyes).

RESULTS

There were no significant between-group differences in uncorrected visual acuity, best-corrected visual acuity, keratometric astigmatism, and endothelial cell count. One day postoperatively, a greater increase of corneal thickness at the incision site was observed in group 1 compared to group 2 using anterior segment optical coherence tomography with no significant differences in tunnel morphometric features and confocal microscopy showed more tunnel edema in group 1 versus group 2 that resolved in both groups.

CONCLUSION

Both 1.8- and 2.2-mm torsional MCCS were safe and efficient with easy surgical maneuvers and excellent functional and morphological results; 1.8-mm MCCS induced slightly greater tunnel edema shortly after surgery that resolved in the medium term.

Aspheric microincision intraocular lens implantation with biaxial microincision cataract surgery: efficacy and reliability

PURPOSE

To evaluate the efficacy and reliability of a microincision intraocular lens (IOL) and its use in biaxial microincision cataract surgery (MICS).

SETTING

Atatürk Training and Research Hospital, Ankara, Turkey.

DESIGN

Prospective clinical study.

METHODS

A microincision IOL (Akreos MI60) was implanted after cataract extraction by the biaxial MICS technique. Over a postoperative follow-up of 12 months or more, visual acuity, contrast sensitivity, surgically induced astigmatism (SIA), corneal and ocular aberrations, and early and late complications were recorded.

RESULTS

The IOLs were implanted in the capsular bag in all 100 eyes. The mean final incision size was 1.82 mm ± 0.09 (SD). Postoperatively, the mean corrected distance visual acuity was 0.06 ± 0.10 logMAR; the mean spherical equivalent, -0.48 ± 0.91 diopter (D); and the mean calculated SIA, 0.20 ± 0.22 D. Contrast sensitivity with and without glare was within normal limits. There was no statistically significant difference in the root mean square of total corneal aberrations between preoperatively and postoperatively. Ocular wavefront analysis 3 months postoperatively showed mean values of 0.15 ± 0.2 μm for spherical aberration, 0.38 ± 0.16 μm for higher-order aberrations, 0.18 ± 0.14 μm for coma, and 0.14 ± 0.08 μm for trefoil. The 4 cases (4.0%) of membranous anterior chamber reaction resolved with treatment. None of the 20 eyes (20.0%) with posterior capsule opacification required neodymium:YAG capsulotomy. All IOLs remained well centered.

CONCLUSION

The aspheric microincision IOL was safely implanted through a 1.8 mm or smaller incision during biaxial MICS and gave good postoperative outcomes.

Wavefront analysis, contrast sensitivity, and depth of focus after cataract surgery with aspherical intraocular lens implantation

PURPOSE

To determine whether implantation of an aspherical intraocular lens (IOL) results in reduced ocular aberrations and improved contrast sensitivity after cataract surgery without critical reduction of depth of focus.

DESIGN

Double-blinded, randomized, prospective study.

METHODS

In an intraindividual study of 25 patients with bilateral cataract, an aspherical IOL (Akreos Advanced Optic [AO]; Bausch & Lomb, Inc., Rochester, New York, USA) was implanted in one eye and a spherical IOL (Akreos Fit; Bausch & Lomb, Inc) in the fellow eye. Higher-order aberrations with a 5- and 6-mm pupil were measured with a dynamic retinoscopy aberrometer at 1 and 3 months after surgery. Uncorrected and best-corrected visual acuity and contrast sensitivity under mesopic and photopic conditions also were measured. Distance-corrected near and intermediate visual acuity were studied as a measurement of depth of focus.

RESULTS

There was no statistically significant difference between eyes in uncorrected and best-corrected visual acuity at 1 and 3 months after surgery. There was a statistically significant between-group difference in contrast sensitivity under photopic conditions at 12 cycles per degree and under mesopic conditions at all spatial frequencies. The Akreos AO group obtained statistically significant lower values of higher-order aberrations and spherical aberration with 5- and 6-mm pupils compared with the Akreos Fit group (P < .05). There was no significant difference in distance-corrected near and intermediate visual acuity between both groups.

CONCLUSIONS

Aspherical aberration-free Akreos AO IOL induced significantly less higher-order aberrations and spherical aberration than the Akreos Fit. Contrast sensitivity was better under mesopic conditions with the Akreos AO with similar results of depth of focus.

Bimanual microincisional cataract surgery technique and clinical outcome

Bimanual microincisional cataract surgery has been introduced recently as a technique for cataract surgery and it is gaining interest of many cataract surgeons in the world. Over the last few years many changes were made in the phacoemulsification machines and the intraocular lenses design which allowed bimanual microincisional cataract surgery to be safer and more efficient. The purpose of this review is to introduce the technique of bimanual microincisional cataract surgery and to review all the prospective randomized studies comparing bimanual microincisional cataract surgery and standard phacoemulsification in term of safety and efficacy parameters.