Effect of residual astigmatism and defocus in eyes with trifocal intraocular lenses

To assess the effect on visual function of different residual astigmatic situations combined with 0.50 diopters (D) negative defocus at different distances in patients with trifocal intraocular lenses (IOLs).

Clínica Rementería, Madrid, Spain.

Prospective case series.

The study included patients implanted with AcrySof IQ PanOptix IOL. Visual acuity (VA) was measured at far distance (0.00 D of vergence) and at -1.5 D, -2.5 D, and -3.0 D of vergence. Residual astigmatism was induced by adding 0.50 D and 1.00 D cylindrical lenses placed at 90 degrees (against the rule [ATR]), 45 degrees (oblique), and 180 degrees (with the rule). All measurements were made with distance correction (emmetropia as the reference situation) and with a simulated residual myopia of 0.50 D.

The study included 61 eyes of 61 patients. Residual astigmatism of 0.50 D and 1.0 D was induced in 28 and 33 eyes, respectively. For both groups, distance and intermediate VAs were better for the reference situation (P < .001 for all cases). With 1.0 D of cylinder (without and with induced defocus), the proportion of patients who lost ≥2 lines was higher for the ATR astigmatism. For near vision, differences were smaller for all simulated situations.

Residual astigmatism of up to 0.50 D, regardless of its orientation, seems to be tolerated at all distances. For astigmatisms of 1.0 D, distance and intermediate VAs decreased significantly, and ATR orientations showed worse results in a higher proportion of patients. The combination of astigmatism with residual myopia significantly decreased distance VA, whereas this negative shift affected near VA less.