Reducing Corneal Cylinder Power After Micro-Incision Cataract Surgery Using Adapted Clear Corneal Incisions – A Retrospective Comparative Cohort Study.

After micro-incision cataract surgery (MICS) with implantation of an aspherical, monofocal intraocular lens (IOL), spectacle dependency for daily activities due to postoperative astigmatism may limit patient satisfaction. The purpose of this study was to evaluate to what extent corneal cylinder > 1 D can be reduced using a simple algorithm to adjust the MICS main incision placement, size, and use of an opposite clear corneal incision (OCCI) according to preoperative corneal keratometric data.

Linköping University Hospital, Department of Ophthalmology, Linköping, Sweden. Cataract surgery equipment compatible with MICS (incision size 2.0mm or less).

In a retrospective controlled cohort study we enrolled 80 eyes with corneal cylinder > 1.0 D, who underwent MICS with adapted clear corneal incisions according to a simple algorithm depending on corneal cylinder power and axis. As controls we included 80 eyes with corneal cylinder > 1.0 D undergoing MICS with a standardized 2.0mm main incision in clear cornea at axis 170°. Data on corneal keratometric cylinder power (KCP) before surgery, and on refractive cylinder power (RCP) before and after surgery was retrieved for all included eyes. KCP data after surgery was available for 57 eyes with adapted incisions and 49 controls. We compared the intra-individual differences in KCP and RCP before and after surgery.

On average, KCP decreased 0.69 D (max range -3 to +3 D) after adapted incisions. For control eyes, mean KCP decreased 0.04 D (max range -1.25 to +1.25 D).  With adapted incisions, KCP decreased in 38 eyes (66.7%), increased in 12 eyes (21%) and was unchanged in 7 eyes (12.3%). Corresponding figures in control eyes were 36.7%, 36.7%, and 26.6%, respectively (p = 0.013 Chi²).

Mean RCP decreased 0.23 D after adapted incisions (range -3.5 to + 2 D), and increased on average 0.17 D in the control group (range -3 to + 4 D). RCP increased for the control group in 49% of cases and improved or remained unchanged in 51%, while 25% had increased cylinder power and 75% improved or were unchanged among patients with adapted incisions (p < 0.001 Chi²).

Postoperative corneal as well as subjective refraction cylinder power can be significantly decreased with clear corneal incisions placed according to a simple algorithm based on preoperative cylinder power and axis at MICS with implantation of an aspherical, non-torical IOL. Future studies are mandated to follow up long-term outcomes in refraction and corneal structure, as well as to determine how this decrease in corneal and refraction cylinder power may decrease need for astigmatic correction after cataract surgery.