Visual outcomes of successful versus failed big-bubble deep anterior lamellar keratoplasty for keratoconus

Purpose: to compare the visual outcomes of deep anterior lamellar keratoplasty (dalk) for keratoconus with and without successful big-bubble formation. methods: in this retrospective comparative study,a total of 289 consecutive eyes from 257 patients underwent dalk using the big-bubble technique. in cases where the big bubble could not be accomplished,manual stromal dissection down to descemeton membrane (dm) was performed using a crescent knife. visual acuity and refractive outcomes were compared between the bare dm group (group 1) and manual dissection group (group 2). results: a bare dm was successfully achieved in 229 (79.2%) eyes and manual dissection was performed in 60 (20.8%) eyes. the study groups were comparable in terms of age (p = 0.79),preoperative best-spectacle corrected visual acuity (bscva) (p = 0.15),and follow-up duration (p = 0.73). postoperative bscva was significantly better in group 1 than in group 2 throughout follow-up (p < 0.05). in group 2,bscva was significantly lower in eyes with advanced keratoconus as compared to those with moderate keratoconus (p = 0.007). at final follow-up,bscva ≤ 0.30 logarithm of minimum angle of resolution (logmar) was achieved in 82.1% of eyes in group 1 versus 54.5% of eyes in group 2 (p < 0.001). groups 1 and 2 were comparable in terms of postoperative spherical equivalent refractive error (p = 0.61) and keratometric astigmatism (p = 0.39). conclusion: retention of the posterior corneal stroma which occurs with manual dissection during failed big bubble formation in dalk is associated with lower visual acuity as compared to achieving a bare dm. © 2016 journal of ophthalmic and vision research.