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Biometry prediction errors, corneal astigmatism may prevent emmetropia after cataract surgery
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Pre-existing corneal astigmatism and biometry prediction errors may lead to failed emmetropization after cataract surgery, according to a study.
“This should spur further fine-tuning of IOL calculation formulas, especially for astigmatic eyes and ametropic eyes. Furthermore, cataract surgeons today must consider ways of dealing with pre-existing corneal astigmatism when aiming for emmetropia,” the study authors said.
The prospective cohort study analyzed 17,056 cataract surgery procedures for postoperative refraction and 7,448 procedures for corneal astigmatism.
The planned target spherical equivalent was recorded preoperatively for the eye undergoing cataract surgery. Corrected distance visual acuity and refraction, including refractive astigmatism, were measured 1 to 2 months postoperatively in both eyes.
Emmetropia was characterized as spherical equivalent from –0.50 to +0.50 D and astigmatism of less than 1 D.
Emmetropia, which was targeted in 78.1% of eyes, was achieved in 52.7% of eyes; 43% of eyes had less than 1 D of astigmatism.
Pre-existing corneal astigmatism and biometry prediction errors were the two largest factors that precluded emmetropia, the study authors said. The mean absolute biometry prediction error was 0.402 ± 0.388 D. The biometry prediction was less accurate in eyes with higher preoperative corneal astigmatism (P < .001).
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