Evaluation of Astigmatic Correction Using Vector Analysis after Combined Femtosecond Laser-Assisted Phacoemulsification and Intrastromal Arcuate Keratotomy

Symmetrical femtosecond laser arc incision in correcting corneal astigmatism in cataract patients

AIM

To evaluate the effect of symmetrical arc incision correcting corneal astigmatism in femtosecond laser-assisted phacoemulsification (FLACS).

METHODS

This study enrolled patients with cataract combined with regular corneal astigmatism of >0.75 D, who underwent FLACS. Symmetrical arc incision was set at 8 mm diameter and 85% depth. The follow-up time was 3-24mo (4.92±3.49mo). Pentacam recorded the corneal astigmatism and higher-order aberration at pre-operation and post-operation. The changes in corneal astigmatism were analyzed by Alpins method. The correlation of astigmatism type, age, corneal horizontal diameter, corneal thickness, arc incision length, and correction index (CI) was analyzed, and the residual corneal astigmatism was compared with the residual whole eye astigmatism.

RESULTS

Totally 79 patients (102 eyes) were enrolled, 10 patients had corneal epithelial injury, 1 patient occurred corneal epithelial hyperplasia. The corneal astigmatism was 1.23±0.38 D pre-operation, and decreased to 0.76±0.39 D post-operation (t=10.146, P=0.000). Corneal high-order aberration was 0.17±0.08 µm pre-operation and 0.24±0.11 µm post-operation (t=-5.186, P=0.000). The residual corneal astigmatism and residual whole eye astigmatism were no significant difference (t=-0.347, P=0.729). Using Alpin's method, the following were determined: target-induced astigmatism (TIA) =1.23±0.38 D, surgery-induced astigmatism (SIA) =0.77±0.45 D, difference vector (DV)=0.77±0.39 D, and CI=0.54±0.28. Age, astigmatism size, corneal horizontal diameter, corneal thickness, and arc incision length were not correlated with CI. The CI for against the rule astigmatism (ATR) was better than that for with the rule astigmatism (WTR; P=0.001).

CONCLUSION

Femtosecond laser-assisted astigmatic keratotomy has better CI of ATR, but increase higher-order corneal aberration. CI is not ideal, it's not a perfect choice if we pursue ideal correction effect.

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

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

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.