Validation of Clinical Protocol of Astigmatism Induction in Pseudophakic Patients

Validate a novel approach for assessing residual astigmatism's impact on visual acuity in pseudophakic patients using defocus curves and spherical equivalent compensation.

Thirteen patients over 40 with cataracts and normal ophthalmological examinations were enrolled in a prospective, non-randomized cohort study. The defocus curve method was employed, wherein visual acuity was measured with spherical lenses ranging from -2.50 to +2.50 diopters in 0.5 diopter increments based on subjective refraction. Cylindrical lenses (+1, +2, and +3 diopters) were introduced at each spherical diopter's 90° and 180° axes. Curves' results were compared at each defocus point to assess the impact of astigmatism. The Kruskal-Wallis test was used to determine if astigmatism significantly affected visual acuity post-phacoemulsification surgery with intraocular lens implantation.

Significant p-values were observed only for defocus curve points of -0.5, 0, +0.5, and +1, indicating rejection of the hypothesis of no difference between the 90° and 180° groups at these points. Although statistical significance was not achieved, the against-the-rule (ATR) group was inclined toward improved near and intermediate visual acuity. In contrast, the with-the-rule (WTR) group tended to enhance distance visual acuity and myopic tolerance.

This novel methodology is both reproducible and valuable. It offers potential insight into residual astigmatism tolerance in pseudophakic patients. Its application may aid in surgical planning and intraocular lens decision-making.