PURPOSE. We evaluated retrospectively the morphologic choroidal and scleral characteristics in eyes with pathologic myopia using high-penetration optical coherence tomography (HP-OCT) or swept-source OCT (SS-OCT). METHODS. The subfoveal choroidal and scleral thicknesses were measured using the prototype HP-OCT with a 1060 nm light source. We also measured the scleral thickness 3 mm superior, inferior, nasal, and temporal to the fovea on the horizontal and vertical OCT sections. The axial length (AL) in all eyes was measured using optical biometry. RESULTS. We examined 58 eyes of 35 patients (7 men and 28 women, mean age 65.5 years) with an AL exceeding 26.5 mm. The mean AL was 29.0 +/- 1.4 mm. The full-thickness choroid and sclera were visualized in all eyes. The mean subfoveal choroidal and scleral thicknesses were 52 +/- 38 and 335 +/- 130 mu m, respectively. The mean scleral thicknesses 3 mm superior, inferior, nasal, and temporal to the fovea were 266 +/- 78 (n = 57), 259 +/- 72 (n = 56), 324 +/- 109 (n = 39), and 253 +/- 79 (n = 58) mu m, respectively. The subfoveal sclera was thicker than 3 mm outside the fovea (P < 0.05, for each comparison). CONCLUSIONS. The full-thickness choroid and sclera in all eyes with pathologic myopia were visualized using a prototype HP-OCT. The subfoveal sclera was thicker than 3 mm outside the fovea. HP-OCT is a useful tool for morphologic analyses of pathologic myopia. (Invest Ophthalmol Vis Sci. 2012;53:3834-3838) DOI:10.1167/iovs.12-9811