In Reply We thank Allingham and Shields for their kind interest in our article on the optic disc appearance associated with bihemispheric retinal nerve fiber layer (RNFL) defects in patients with early glaucoma.1 Concerns have been raised regarding how the disc dimensions were determined in this study. Optic disc tilt is thought to result from posterior scleral expansion, especially in myopic eyes.2 It might reflect the overall changes in the posterior peripapillary sclera beyond the lamina cribrosa, which is associated with the pathogenesis of glaucoma.3 In this study, the amount of optic disc tilt was measured using the ovality index, and the horizontal tilt angle was measured using optical coherence tomography. Compared with the single-hemispheric RNFL defect group, the optic disc ovality was 0.09 greater (95% CI, −0.14 to −0.03; P = .001) and the optical coherence tomography–measured horizontal tilt angle was 1.76° larger (95% CI, −3.47 to −0.03; P = .045) in the bihemispheric RNFL defect group.
Choi JA, Park CK. Potential Effect of the Presence of Gray Crescent on Analysis of Optic Disc and Retinal Nerve Fiber Layer Defects—Reply. JAMA Ophthalmol. 2015;133(5):618. doi:10.1001/jamaophthalmol.2014.5331