PURPOSE: To investigate the anterior segment morphology in cataracts with retinitis pigmentosa (RP). SETTING: The Jikei University Hospital. DESIGN: Retrospective matched case-control study. METHODS: The analysis included 28 eyes of 28 patients with cataracts and RP and 28 eyes of 28 patients with cataracts but without RP, matched for age and sex. Lens thickness, anterior lens curvature (Front R), posterior lens curvature, anterior chamber depth (ACD), anterior chamber width, central corneal thickness (CCT), white-to-white (WTW) distance, corneal curvature, and axial length (AL) were compared between the groups. Data were obtained from preoperative evaluations conducted before cataract surgery. The same set of comparisons was also conducted for 18 eyes of 18 patients with cataracts and RP and 18 eyes of 18 patients with cataracts but without RP, matched for age, sex, and AL. Cases with missing data, categorized as Emery-Little classification grade 4 or above, or those with a history of acute angle closure were excluded. RESULTS: In the age and sex-matched analysis, cataracts with RP showed a significantly thicker lens, steeper Front R, shallower ACD, thinner CCT, and shorter AL. In the analysis matched by age, sex, and AL, cataracts with RP had a thicker lens, steeper Front R, and larger WTW distance. CONCLUSIONS: Cataracts with RP demonstrated centripetal swelling of the lens, centrifugal corneal thinning, and AL shortening. A decrease in tension between the lens and eyeball wall because of zonular weakness in the RP may lead to swelling of the lens and horizontal flattening of the eyeball.