Importance Primary congenital glaucoma (PCG) surgery often leaves residual visual impairment in children. Evidence comparing rigid gas-permeable contact lenses (RGPCLs) vs spectacles for rehabilitation is needed. Objective To compare the use of RGPCLs vs continued spectacle wear for improving visual outcomes for children after PCG surgery. Design, Setting, and Participants This randomized clinical trial was conducted at Zhongshan Ophthalmic Center, a tertiary referral center in Guangzhou, China, from April 21, 2022, to August 21, 2023. Participants comprised 56 children (aged 4-15 years) with surgically managed PCG and poor spectacle response. Data were analyzed from October 11, 2023, to March 21, 2024. Interventions RGPCLs (n = 29) vs spectacles (n = 27) for 12 months, plus standardized amblyopia patching. Main Outcomes and Measures The primary outcome was change in worse-eye best-corrected visual acuity (BCVA) at 12 months measured by the Early Treatment Diabetic Retinopathy Study chart with tumbling-E optotypes with children wearing their current best refractive correction. Secondary outcomes included contrast sensitivity function and near stereoacuity. Results Among 56 (of a total of 83 screened participants) randomized participants, 48 (85.7%) completed at least 1 follow-up visit and were included in the primary analysis. Baseline demographic and ocular characteristics for the RGPCL group vs the spectacles group included a mean (SD) age of 7.7 (2.7) vs 7.2 (3.2) years, 13 (54.2%) vs 14 (58.3%) male, and 11 (45.8%) vs 10 (41.7%) female. At 12 months, 22 of 29 participants (76.0%) in the RGPCL group and 19 of 27 participants (70.4%) in the spectacles group completed the final visit. The mean (SD) baseline worse-eye spherical equivalent was −6.55 (6.43) vs −5.17 (5.27) diopters, the mean (SD) BCVA was 0.99 (0.71) vs 1.02 (0.74) logMAR (approximate Snellen equivalent 20/200), and the mean (SD) intraocular pressure was 14.98 (3.14) vs 13.36 (3.92) mm Hg in the RGPCL vs the spectacles group, respectively. At 1 year, the RGPCL group had greater BCVA improvement (mean [SD], 0.31 [0.28] vs 0.12 [0.33] logMAR; adjusted treatment difference, −0.19 logMAR; 95% CI, −0.36 to −0.02 logMAR [approximately 10 letters]; P = .03). Achievement of 2 or more lines of BCVA improvement occurred in 15 of 24 participants (62.5%) in the RGPCL group vs 9 of 24 participants (37.5%) in the spectacles group (odds ratio, 6.83; 95% CI, 1.81-25.73; P = .01). The RGPCL group had greater contrast sensitivity function improvement (0.40 [0.27] vs 0.13 [0.32]; adjusted treatment difference, 0.24 log units; 95% CI, −0.01 to 0.49; P = .04). Near stereoacuity of 60 arcseconds or less was achieved by 12 participants (50.0%) vs 6 of 24 participants (25.0%) (odds ratio, 6.96; 95% CI, 2.41-6.51; P = .001). No serious adverse events occurred. Conclusions and Relevance These findings suggest that RGPCLs provided superior visual acuity and contrast sensitivity improvement vs continued spectacle wear for children after PCG surgery. These findings support using RGPCLs for children undergoing PCG surgery, including those with worse baseline visual acuity or poor spectacle response. Trial Registration Chinese Clinical Trial Registry Identifier: ChiCTR2100043776