Purpose: To investigate morphologic features along posterior staphyloma edges in eyes with pathologic myopia using ultra-widefield optical coherence tomography imaging. Methods: Highly myopic patients (refractive error, <-8 diopters or axial length >= 26.5 mm) were consecutively examined by prototype ultra-widefield optical coherence tomography with a scan width of 23 mm and depth of 5 mm. Staphyloma edges were assessed for scleral, choroidal, and retinal status, as well as measurements of angle size. Findings were correlated with pigmentary changes observed on Optos fundus photography, and multivariate logistic regression analyses were performed. Results: In 164 eyes diagnosed with posterior staphyloma by ultra-widefield optical coherence tomography, choroidal thinning and scleral protrusion were hallmark features of staphyloma edges, observed simultaneously in more than 95% of staphylomatous eyes. Outer neural retinal thinning was observed in 80 eyes (48.8%), whereas 15 eyes (9.1%) showed retinal pigment epithelium damage. The mean angle at the staphyloma edge was 23 degrees +/- 12.4 degrees (range 8 degrees to 77 degrees). Larger angles were significant predictors of retinal thinning (adjusted odds ratio: 1.17, confidence interval: 1.09-1.25), and the staphyloma was detected by Optos pseudocolor fundus photography (adjusted odds ratio: 1.08, confidence interval: 1.02-1.15). Conclusion: These morphologic findings may provide a basis for exploring the natural evolution of posterior staphyloma as part of the development of pathologic myopia.