Low corneal astigmatism: refractive outcomes after cataract surgery
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First Author: D.Maleita PORTUGAL
Co Author(s): D. Maleita P. Gil D. Hipólito-Fernandes V. Maduro N. Alves J. Feijão
To report the astigmatic refractive outcomes of low corneal astigmatism (0.75-1.50 diopters, D) patients after cataract surgery.
Refractive Surgery Unit, Ophthalmology Department, Centro Hospitalar Universitário de Lisboa Central, Lisbon, Portugal
Retrospective case-series. The records of consecutive patients submitted to age-related cataract surgery with the same monofocal spherical intraocular lens (IOL) between 1st January and 30th April 2019 were reviewed. All patients with corneal astigmatism between 0.75-1.50D measured with the Lenstar 900 were included. All procedures were performed with a 2.75mm clear corneal incision by a large number of surgeons in a university-hospital setting. No restriction was applied based on the surgeon preference of axis of corneal incision. Astigmatism was classified as with the rule (WTR), against the rule (ATR) and oblique, according to the orientation of the steep meridian.
A total of 312 eyes from 312 patients were included. Mean preoperative corneal astigmatism was 1.07±0.22D, distributed across: ATR (n=175, 56.09%); WTR (n=85, 27.24%) and oblique (n=52, 16.66%). Postoperative refractive astigmatism was ≤0.50D in 19% and ≤0.75D in 36% of cases. Overall mean difference between the magnitude of refractive and corneal astigmatism was -0.05±0.51D; while WTR patients showed a reduction, astigmatism actually increased in ATR patients (-0.34±0.43 vs. 0.11±0.48; p<0.001). The best multivariate model showed that, adjusting for the magnitude of corneal astigmatism (β=-0.16; p=0.004), the presence of ATR astigmatism (β=0.43; p<0.001) significantly influenced the decrease in refractive astigmatism.
A retrospective benchmarking analysis revealed that, when pooling data from a large multi-surgeon university hospital, refractive outcomes after cataract surgery in patients with low corneal astigmatism vary widely. Particularly in cases with preoperative ATR astigmatism, careful planning is mandatory for optimal results, which might include adjustments in incision location, limbal relaxing incisions or toric IOLs, strategies that might not be adequate in a teaching environment.