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Intraoperative Review of Different Bubble Types Formed During Pneumodissection (Big-Bubble) Deep Anterior Lamellar Keratoplasty

Purpose: To evaluate the preoperative factors and intraoperative complications of the 2 bubble types formed during big-bubble deep anterior lamellar keratoplasty (DALK). Methods: This is a retrospective review of medical records of a series of patients who underwent DALK using the big-bubble technique from September 2009 to March 2014. Results: A total of 134 eyes were included in this study—89 eyes with advanced keratoconus, 35 eyes with post-microbial keratitis corneal scars, 8 eyes with stromal dystrophies, and 2 eyes with post–laser in situ keratomileusis ectasia. A type 1 bubble (white margin) was achieved in 56 eyes (41.8%), whereas a type 2 bubble (clear margin) was formed in 14 eyes (10.4%) and a mixed bubble was formed in 2 eyes (1.5%). Big-bubble formation failed in 62 (46.3%). All eyes with the type 1 bubble were completed as DALK; microperforation occurred in 4 eyes. Twelve of 14 eyes with the type 2 bubble were converted to penetrating keratoplasty because of large perforations. Conclusions: The type 2 bubble is more likely to form in elderly patients and those with deep corneal scars and thin corneas. Because of the high rate of conversion to penetrating keratoplasty, better surgical strategies may be needed to manage type 2 bubbles.