Trifocal IOLs have become popular among cataract surgeons due to their satisfactory clinical outcomes and the high rates of spectacle independence they offer. Still, small refractive errors, which have been traditionally regarded as successful refractive outcomes, might have a significant impact on visual function and, therefore, on patient satisfaction.

To evaluate the visual performance of patients who received a trifocal IOL and have small refractive errors, researchers in Spain induced either myopia or hyperopia over an ideal emmetropic situation with a positive and negative defocus of 0.50D. While most patients implanted with trifocal IOLs can tolerate low residual refractive errors, a significant number may experience decreased visual quality, increased photic phenomena or both.

The study included 60 eyes of 60 patients—one half had the AcrySof IQ PanOptix IOL (Alcon) and the other had the PanOptix Toric IOL (Alcon). The researchers assessed VA at high (100%), medium (50%) and low (10%) contrast, contrast sensitivity function (CSF) and halo perception three months after cataract surgery. They also tested these results under CDVA and with a positive and negative defocus of 0.50D.

Both IOL groups experienced better VA with each contrast setting when taking CDVA into account. For low spatial frequencies, there was no difference in CSF among the three different refractive approaches in either group. As the frequencies increased and the resolution of fine details became more demanding, the results showed more variability. For higher frequencies, there was an overall trend for better CSF when no residual refractive error was induced. The halo effect was less prevalent in the case of CDVA compared with the positive and negative defocus assessments.

“For gross visual details, some degree of residual refractive error seems to be negligible; whereas, fine detail resolution could be affected even with low residual refractive errors, whether they are positive or negative,” the researchers wrote in their paper.

They concluded that residual refractive errors within ±0.50D should not always be considered a refractive success after IOL implantation.

Rementería-Capel LA, Contreras I, García-Perez JL, et al. Tolerance to residual refractive errors after trifocal and trifocal toric intraocular lens implantation. Eye Cont Lens. December 11, 2020. [Epub ahead of print].