Ocular changes associated with topiramate. 
To determine the changes in refractive error, and the cornea, anterior chamber, and retina induced by topiramate.  The study included 76 eyes of 38 patients that began to use topiramate due to migraine.  Following ophthalmological examination, all of the patients underwent central corneal thickness (CCT), anterior chamber volume (ACV), anterior chamber depth (ACD), and anterior chamber angle (ACA) measurement using a Scheimpflug camera, as well as macular thickness, retinal and retinal nerve fiber layer thickness (RNFLT) measurements using optical coherence tomography (OCT).  These procedures were repeated 15, 30, and 90 days after the initiation of topiramate therapy.  The median refractive error value showed a statistically significant increase from -0.25 diopters (D) to -0.62 D at the 90th day follow-up (P < 0.001).  Mean CCT was 570.56 µm before treatment and increased to 573.69 µm at the 15th day follow-up, 575.31 µm at the 30th day follow-up, and 574.56 µm at the 90th day follow-up; however, these changes were not statistically significant.  Mean ACV, ACD, and ACA did not exhibit statistically significant changes.  Mean retinal thickness (RT) increased during the treatment from 263.46 µm to 271.60 µm, which was not statistically significant.  The initial mean RNFLT was 100.56 ± 15.36 µm and significantly increased to 110.2 ± 8.41 µm and 111.03 ± 14.59 µm at the 30th and 90th day follow-ups, respectively (P = 0.01 and P = 0.004, respectively).  During the 3-month follow-up of patients using topiramate 50 mg d(-1) significant myopic shift and an increase in RNFLT were observed.  Further studies are warranted in order to assess the effects of topiramate when used long term and at higher doses.