Refractive Change Induced by 2.8-mm Corneal Incision

The investigators\' purpose is to study the induced refractive change caused by different 2.8-mm corneal incision locations in phacoemulsification, because the investigators hypothesize that the effect may be different for nasal, temporal, and superior location, although they are considered astigmatism neutral. Patients will be randomized to nasal or temporal incision, or assigned to superior incision, depending on preexisting astigmatism. Visual acuity, refraction, keratometry, Pentacam analysis, intraocular pressure, biomicroscopy, and funduscopy, will be carried out before and after phacoemulsification. Outcome measures will be induced corneal refractive change (Fourier power vector analysis), ISV change, and visual acuity, at 6 months.