CONCLUSIONS Specular microscopic parameters were found to be decreased in patients with primary congenital glaucoma (PCG). Patients with PCG and Haab striae had lower endothelial cell density (ECD) and central corneal thickness (CCT) than those without Haab striae did. The type of surgery (viscogoniotomy, viscotrabeculotomy, or combined viscotrabeculotomy and trabeculectomy) did not affect specular microscopic parameters. OBJECTIVE The purpose of this study was to compare specular microscopic parameters such as corneal ECD, coefficient of variation (CV), hexagonal cell percentage (HEX), and CCT between patients with PCG and healthy controls; to determine the predictive ability of Haab striae for endothelial cell changes PCG by comparing patients with and without Haab striae; and to investigate if the type of surgery used to treat glaucoma (viscogoniotomy, viscotrabeculotomy, or combined viscotrabeculotomy and trabeculectomy) affects specular microscopic parameters. METHODS A cross-sectional specular microscopic analysis of patients with PCG and healthy controls was performed. One hundred eyes of 62 patients with PCG with and without Haab striae and 101 eyes of 101 healthy controls were enrolled in this study. Specular microscopic parameters, including ECD, HEX, CV, and CCT, of all subjects were evaluated. RESULTS Patients with PCG showed significantly lower ECD and CCT than healthy controls did. Those with Haab striae had lower ECD and CCT but no differences in age, HEX, and CV compared with those without Haab striae. ECD, CV, HEX, or CCT did not significantly differ among patients treated with the 3 different types of surgery. CONCLUSIONS Prolonged exposure to elevated intraocular pressure during prenatal and/or early postnatal life results in structural changes in immature infant corneas. Specular microscopic parameters differed significantly between healthy controls and patients with PCG. The type of surgery had no effect on these parameters. Among patients with PCG, those with Haab striae had isolated corneal endothelial cell loss without morphologic changes within the endothelium.