Corneal optical quality following sub 1.8 mm micro-incision cataract surgery vs. 2.2 mm mini-incision coaxial phacoemulsification

Purpose: To study and compare the effects of the micro-incision cataract surgery (MICS-sub 1.8 mm) and mini-incision coaxial phacoemulsification (2.2 mm) on the optical quality of the cornea characterized in terms of corneal aberrations. Materials and Methods: Fifty eyes underwent MICS and 50 mini-incision phacoemulsification, by the same surgeon. Both types of cataract surgery were performed using low ultrasound power and through a clear corneal incision, placed on the steepest corneal meridian ranging from 1.6 to 1.8 in MICS (Group I) and from 2.12 to 2.3 mm in mini-incision coaxial phacoemulsification (Group II). Seidel and Zernike aberration coefficients and RMS values were obtained for a 6-mm pupil preoperatively and one month after surgery. Results: The corneal astigmatism did not show statistically significant changes in either of the two groups: (MICS: -0.73 ± 0.63, -0.65 ± 0.53 D, P = 0.25), (mini-incision phacoemulsification; -1.21 ± 1.52, -1.00 ± 1.19 D, P = 0.12). The total RMS remained unchanged after MICS (1.77 ± 1.7, 1.65 ± 1.3 μm, P = 0.18) and mini-incision phacoemulsification (2.00 ± 1.87, 2.09 ± 1.8 μm, P = 0.41). Statistically significant changes were found for coma (P = 0.004) and higher-order aberrations (P < 0.001), showing MICS significantly less changes in cornea. Conclusions: Both MICS and mini-incision phacoemulsification do not degrade the optical quality of the cornea. Both surgeries do not induce a modification of the corneal astigmatism, even in the axis. It seems that 2 mm is the limit around which no optical changes are induced by cataract surgery in the human cornea.