Preoperative Astigmatism Planning: High-Tech Isn’t Necessarily Better

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A study evaluating outcomes after astigmatism correction found that an image-guided system and in­traoperative aberrometer, when used together, yielded outcomes that were not significantly better than the surgeon’s standard of care.¹

The findings, however, are dependent on the sur­geon’s use of “modern and advanced formulas with accurate preoperative measurements and detailed attention to all aspects of the preoperative evaluation,” said Kerry D. Solomon, MD, a cataract specialist in Mount Pleasant, South Carolina.

Study design. This prospective case series involved patients who were having uncomplicated bilateral cataract extraction or refractive lens exchange with IOL implantation and astigmatism correction. Dr. Solomon performed all of the surgeries.

The patients served as their own controls, and their eyes were randomly assigned to two groups: 1) Group A eyes received Dr. Solomon’s standard of care. He used Lenstar LS 900 (Haag-Streit) keratotomy and calculator/nomogram to determine toric power and orientation of astigmatic incisions. 2) For eyes in Group B, Dr. Solomon used the Verion image-guided system (Alcon) to preoperatively determine the placement of the toric IOL or incision. He also used the Optiwave Refractive Analysis system with VerifEye+ (Alcon) for intraoperative aberrometry calculations.

Results. All told, 38 eyes received toric IOLs, and 40 eyes received manual limbal-relaxing incisions. No significant differences in outcomes between the two groups were noted. Other results were as follows:

• On average, toric IOLs resulted in approximately 0.25 D less cylinder than corneal astigmatic incisions. This was consistent with a large meta-analysis report­ing lower residual astigmatism with toric IOLs than with relaxing limbal incisions.²
• At three months, the IOL in four eyes (11%; two in each group) was more than 10 degrees of absolute orientation from the intended orientation. No eye with a toric IOL had a secondary surgical intervention to reorient the IOL.
• The reduction in residual astigmatism did not im­prove other clinical outcomes, such as uncorrected and corrected distance visual acuity. 

What if? Might the results differ in the hands of other surgeons? “We don’t know for sure if—or how—having a different or less experienced surgeon would have affected the results,” Dr. Solomon said. “But we believe that using older formulas and not following our standard procedures could affect the results.”

—Miriam Karmel

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1 Solomon KD et al. J Cataract Refract Surg. 2019;45(5):569-575.

2 Kessel L et al. Ophthalmology. 2016;123(2):275-286.

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Relevant financial disclosures—Dr. Solomon: Alcon: C,S.

For full disclosures and the disclosure key, see below.

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