We read with interest the article on Terrien marginal degeneration by Chan and associates. The authors mentioned that 7 out of 25 patients (28%) had unilateral disease. However, they did not comment anything about the tomographic features of the contralateral, presumably healthy, eyes. Fernandes reported 2 cases of young patients initially considered to have unilateral Terrien marginal degeneration, with normal slit-lamp examination in the apparently free-of-disease eyes, which showed significant tomographic changes in the Orbscan IIz examination.

Chan and associates indicated that 10 eyes underwent surgical procedures. According to data in the published Table, 50% of those eyes lost lines of best spectacle-corrected visual acuity (BSCVA) following the surgery. Two out of the 3 eyes that gained lines of BSCVA underwent, simultaneously with the lamellar procedure, a phacoemulsification because of cataract. As the authors explained, this might have been a confounding factor in evaluating this improvement. In addition, considering the 2 eyes that underwent isolated lamellar keratoplasty without presenting perforation, only 1 had improved vision, while the other case lost 2 lines of BSCVA. We wonder whether, after looking at the surgical results, the recommendation made by the authors that for advanced cases with prominent thinning performing earlier surgery is really supported by the evidence. We have been observing for several years a couple of patients with advanced Terrien marginal degeneration: one middle-aged woman with a very thin area (about 150 μm) and a young adult male patient with an intracorneal cyst with an anterior wall around 100 μm thick. Both have been very stable according to slit-lamp and anterior segment optical coherence tomography.

In addition, in 2006 Srinivasan and associates showed a case of spontaneous perforation managed with a contact lens. The result of this conservative approach was good. At last follow-up (2 months after the perforation), no recurrence of the perforation had occurred, and visual acuity was maintained at 6/4. It seems possible to attempt this nonsurgical option before performing those more complex and risky surgical alternatives of corneal grafting.