Pseudophakic astigmatism reduction with femtosecond laser-assisted corneal arcuate incisions: a pilot study

Cataract surgery astigmatism incisional management. Manual relaxing incision versus femtosecond laser-assisted arcuate keratotomy. A systematic review

PURPOSE

This systematic review aims to compare corneal astigmatism correction in cataract surgery through corneal relaxing incision, manually and femtosecond laser assisted.

METHODS

The study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement recommendations. We used PubMed, Scopus, and Web of Science (WOS) as databases from January 2010 to March 30, 2021. Patients with keratoconus, corneal ectasia, and a previous history of eye surgery were excluded because our aim was to analyze only healthy eyes.

RESULTS

A total of 1025 eyes were evaluated from 946 patients (mean age was 68.90 ± 5.12) in manual incision group articles, while 1905 eyes of 1483 patients (mean age was 65.05 ± 4.57) were evaluated in femtosecond laser arcuate keratotomy (FLAK) articles. The mean uncorrected distance visual acuity (UDVA) was 0.19 ± 0.12 and 0.15 ± 0.05 logMAR for manual incision and FLAK articles, respectively (p = 0.39). The mean correction index (CI) was similar in both groups: 0.77 ± 0.18 in manual incision and 0.79 ± 0.17 in femtosecond laser assisted incision (p = 0.70). Refractive stability was found after 3 months and no serious complications were reported during the follow-up in any group.

CONCLUSION

Both techniques are safe and moderately effective in corneal astigmatism correction in cataract surgery. FLAK represents a more precise and predictable approach. However, since visual and refractive outcomes appear to be similar in both cases, the cost-benefit analysis is controversial.

Precision and refractive predictability of a new nomogram for femtosecond laser-assisted corneal arcuate incisions

PURPOSE

Validating a new nomogram for low to moderate astigmatism (0.75 D to 2.5 D) correction with epithelium- and Bowman-penetrating femtosecond laser-assisted arcuate incisions.

METHODOLOGY

Prospective, interventional case series at the Augen- und Laserklinik, Castrop-Rauxel, Germany. Cataract patients with low to moderate corneal astigmatism were treated with femtosecond laser-assisted arcuate incisions. Patients with previous refractive corneal treatment were excluded. Outcome assessment was based on manifest refraction, astigmatic vector analysis and visual acuity.

RESULTS

The study analysed 43 eyes of 33 patients after three months and 35 eyes of 27 patients after 12 months. After 12 months, 100% of all eyes treated had ≤1.0 D and 97% ≤0.5 D of subjective residual astigmatism. Mean residual astigmatism was 0.27 D. 90% of all eyes were within one line of difference between UDVA and CDVA. SEQ Mean Absolute Error was 0.26 D and SEQ. Mean error was -0.08 ± 0.32 D. CI was 0.98 ± 0.2 D, and Index of Success, 0.20 ± 0.18 D.

CONCLUSION

The Castrop nomogram showed results that are comparable to or better than results presented in the literature for existing nomograms. Our results for astigmatic reduction are comparable to published results for TIOL implantation. It seems to be a predictable and safe measure to reduce manifest astigmatism.

Refractive outcomes of femtosecond laser-assisted cataract surgery with arcuate keratotomy and standard phacoemulsification with toric intraocular lens implantation

PURPOSE

Femtosecond laser arcuate keratotomy (FS-AK) and toric intraocular lens (IOL) implantation are effective for the correction of eyes with corneal astigmatism. In this study, the postoperative refractive outcomes of patients receiving femtosecond laser-assisted cataract surgery (FLACS) with FS-AK and patients receiving standard phacoemulsification with toric IOL implantation were evaluated.

METHODS

This retrospective study reviewed the postoperative outcomes of patients undergoing FLACS with FS-AK (the FS-AK group) and patients undergoing standard phacoemulsification with toric IOL implantation (the toric IOL group). The main outcome measures were uncorrected and corrected visual acuities, keratometric and refractive astigmatism, and vector analysis.

RESULTS

The FS-AK group included 41 eyes with preoperative keratometric astigmatism of - 1.64 ± 0.42 diopters (D), and the toric IOL group included 53 eyes with preoperative keratometric astigmatism of - 2.29 ± 0.91 D (P < 0.001). Postoperative refractive astigmatism was comparable between the two groups. Compared with the FS-AK group, postoperative uncorrected visual acuity was significantly better (P = 0.005) and corrected visual acuity was marginally better in the toric IOL group (P = 0.051). The absolute angles of error were 9.95° ± 9.57° and 5.08° ± 4.94° (P = 0.02) in the FS-AK and the toric IOL groups, respectively.

CONCLUSION

Both FLACS with FS-AK and standard phacoemulsification with toric IOL implantation are safe and effective methods for astigmatism correction during cataract surgery. Standard phacoemulsification with toric IOL implantation achieves better visual acuity than FLACS with FS-AK at the 6-month follow-up.

Clinical Outcomes of Monofocal Toric IOLs Using Digital Tracking and Intraoperative Aberrometry

Purpose

To evaluate clinical outcomes of a toric IOL using digital tracking (DT) and intraoperative aberrometry (IA).

Methods

This was a retrospective, single surgeon study examining 151 eyes of 106 patients. Inclusion criteria were subjects who presented with visually significant cataracts (or as a candidate for clear lens extraction) and were implanted with a toric intraocular lens. Spherical equivalent prediction errors for IA and preoperative planning were calculated and compared. Preoperative and postoperative refractive data and monocular uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were also collected at 3 months postoperatively.

Results

Postoperative actual residual refractive astigmatism with IA was 0.50 D or less in 140 eyes (92.8%) and was 0.50 D or less in 88 eyes (58.3%) with back-calculations based on preoperative planning. The absolute spherical equivalent prediction error was 0.50 D or less in 135 eyes (89.4%) for IA compared to 123 eyes (85.4%) for preoperative planning. Postoperative monocular UDVA was 0.10 logMAR or better in 124 eyes (82.1%) and 0.00 logMAR or better in 90 eyes (59.6%). Postoperative CDVA was 0.10 logMAR or better in 147 eyes (97.4%) and 134 eyes (88.7%) were 0.00 logMAR or better.

Conclusion

The results demonstrate that toric implantation with DT and IA can provide excellent refractive and visual outcomes.

Clinical Outcomes After Femtosecond Laser-Assisted Arcuate Corneal Incisions versus Manual Incisions

Purpose

To compare the relative effectiveness of Verion-LenSx guided femtosecond arcuate incisions and manual incisions in reducing postoperative refractive astigmatism.

Patients and Methods

This was a contralateral eye, prospective study that included subjects with 0.50 D to 1.75 D of corneal astigmatism who wanted less refractive astigmatism post cataract surgery. The surgeon used anterior keratometry and the Woodcock astigmatism nomogram for preoperative planning, while the LenSx femtosecond laser with the Verion Image Guided System was used to create all laser arcuate incisions. Manual incisions were planned using the Donnenfeld nomogram and made with a fixed-depth diamond knife. The primary outcome measure was the residual refractive astigmatism at 3 months postoperative. Secondary outcome measures included the manifest refraction, uncorrected distance visual acuity and the change in corneal astigmatism from 1 to 3 months postoperative.

Results

Forty-one subjects were successfully enrolled in the study, with data from 38 subjects available at 3 months. There were no statistically significant differences in refractive astigmatism, corneal astigmatism, uncorrected distance visual acuity or manifest refraction between the Manual and Femto groups at either 1 month or 3 months. Significant changes in refractive and corneal astigmatism were noted between 1 months and 3 months. Ninety percent of eyes in both groups had ≤0.50 D of refractive astigmatism at 3 months. Two minor non-serious adverse events (full-thickness incisions of the cornea) occurred in two eyes of two different subjects in the Manual group; they were resolved without incident.

Conclusion

Laser arcuate incisions appear to be an effective means of reducing postoperative refractive astigmatism at the time of cataract surgery. No significant clinical differences were observed between incisions made manually and those made with an image-guided femto-second laser system. The lower number of minor adverse events experienced with the femtosecond laser system is an apparent advantage.

Stepwise candidate drug screening for myopia control by using zebrafish, mouse, and Golden Syrian Hamster myopia models

Background

We developed a preclinical protocol for the screening of candidate drugs able to control myopia and prevent its progression. The protocol uses zebrafish, C57BL/6 mice, and golden Syrian hamster models of myopia.

Methods

A morpholino (MO) targeting the zebrafish lumican gene (zlum) was injected into single-cell zebrafish embryos, causing excessive expansion of the sclera. A library of 640 compounds with 2 matrix metalloproteinase (MMP) inhibitors (marimastat and batimastat), which have the potential to modulate scleral remodelling, was screened to identify candidates for mitigating scleral diameter expansion in zlum-MO-injected embryos. The myopia-prevention ability of compounds discovered to have superior potency to inhibit scleral expansion was validated over 4 weeks in 4-week-old C57BL/6 mice and 3-week-old golden Syrian hamsters with form-deprivation myopia (FDM). Changes in the refractive error and axial length were investigated. Scleral thickness, morphology of collagen fibrils in the posterior sclera, messenger RNA (mRNA) expressions, and protein levels of transforming growth factor-β2 (TGF-β2), tissue inhibitor of metalloproteinase-2 (TIMP-2), MMP-2, MMP-7, MMP-9, and collagen, type I, alpha 1 (collagen Iα1) were investigated in C57BL/6 mice, and MMP-2, MMP-9, and MMP activity assays were conducted in these mice.

Findings

In the zebrafish experiment, atropine, marimastat, batimastat, doxycycline, and minocycline were the drugs that most effectively reduced expansion of scleral equatorial diameter. After 28-day treatment in diffuser-wearing mice and 21-day treatment in lid-sutured hamsters, myopic shift and axial elongation were significantly mitigated by eye drops containing 1% atropine, 50 µM marimastat, 5 µM batimastat, or 200 µM doxycycline. MMP-2 mRNA expression in mouse sclera was lower after treatment with atropine, marimastat, batimastat, or doxycycline. The protein levels and activity of MMP-2 and MMP-7 were significantly reduced after treatment with atropine, marimastat, batimastat, doxycycline, and minocycline. Furthermore, scleral thickness and collagen fibril diameter were not lower after treatment with atropine, marimastat, batimastat, or doxycycline than those of occluded eyes.

Interpretation

Stepwise drug screening in a range of models from zlum-MO-injected zebrafish to rodent FDM models identified effective compounds for preclinical myopia control or prevention. On the basis of the 640 compounds that were screened, MMP inhibitors may offer alternatives for clinical trials.

Funding

This research was supported by grants from Taiwan's Ministry of Science and Technology and Ministry of Health and Welfare.

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

PURPOSE

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

SETTING

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

DESIGN

Retrospective case series.

METHODS

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

RESULTS

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

CONCLUSION

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

How much astigmatism to treat in cataract surgery

PURPOSE OF REVIEW

Astigmatism correction in cataract surgery is a common surgical challenge. Although there are numerous approaches to its treatment during cataract surgery, there remains a lack of consensus on what level of postoperative astigmatism to target. We examine the literature to determine the effect of astigmatism on visual function and provide a recommendation on how much to treat in cataract surgery.

RECENT FINDINGS

Distance visual acuity decreases as myopic, hyperopic, or mixed astigmatism increases. Near visual acuity decreases with hyperopic astigmatism but improves with myopic astigmatism. The effect of astigmatism is generally independent of axis; however, against-the-rule (ATR) astigmatism with mild myopia may benefit reading. A progressive ATR shift occurs with age whether or not an individual undergoes cataract surgery. In the presence of higher order aberrations, correction of astigmatism below 0.5 D shows minimal practical benefit. Presbyopia-correcting intraocular lenses (IOLs) are sensitive to astigmatism but achieve distance visual acuities similar to monofocal IOLs and reach their full near and/or intermediate potential when residual astigmatism 0.5 D or less.

SUMMARY

In cataract surgery, we recommend correction to 0.5 D or less of postoperative residual astigmatism to achieve optimum visual function and patient satisfaction following cataract surgery.

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.

Human lens epithelial cell apoptosis and epithelial to mesenchymal transition in femtosecond laser-assisted cataract surgery

AIM

To evaluate human lens epithelium cell apoptosis and epithelial to mesenchymal transition (EMT) induced by femtosecond laser in femtosecond laser assisted cataract surgery (FLACS).

METHODS

Sixty cataract patients with N2 to N3 stage according to the LOCS III were enrolled in this study and divided into three groups randomly: FLACS1 group (cataract surgery by FLACS with LenSx), FLACS2 group (cataract surgery by FLACS with LensAR) and manual group (cataract surgery by phacoemulsification). Patients in two FLACS groups performed anterior capsulotomy by LenSx or LensAR laser system. Patients in the manual group were performed continuous curvilinear capsulorrhexis (CCC) manually. The anterior capsules were fixed right after moved out of eye. Hematoxylin-eosine staining, immunofluorescence staining and real-time PCR were performed in order to observe human lens epithelium cells changes after cataract surgery.

RESULTS

The capsule cutting edge was shown irregularity and roughness in two FLACS groups and smooth edge in manual capsulotomy by pathologic staining. Irregularities of the cell configuration with partly swollen and destroyed nuclei were observed in two FLACS groups. Femtosecond laser could induce a significantly higher cell apoptosis in human lens epithelium cell than manually performed CCC (P<0.05). Lens epithelium cells apoptosis were correlated with femtosecond laser duration according to Pearson correlation analysis. Decreased N-cadherin expression, alpha-SMA and FSP-1 level in two FLACS groups showed the inhibition of cell EMT.

CONCLUSION

Femtosecond laser may affect the apoptosis and EMT of lens epithelium cells which are under the peeled central lens capsule.

Reviewing the visual benefits of femtosecond laser-assisted cataract surgery: Can we improve our outcomes?

Femtosecond laser-assisted cataract surgery (FLACS) was introduced in 2009 and has increasingly been incorporated into surgical practice. The automation of three key aspects of cataract surgery was expected to deliver a significant improvement in both refractive and safety outcomes. The published literature has not yet shown consistent refractive improvement above conventional techniques. The purpose of this paper is to review current FLACS refractive outcomes and explore factors that may have contributed to the current findings and whether future improvements are possible.