Pachymetry-guided intrastromal air injection ("Pachy-Bubble") for deep anterior lamellar keratoplasty: Results of the first 110 cases

Purpose: To report intraoperative and 1-year postoperative results of the pachy-bubble technique for deep anterior lamellar keratoplasty (DALK). Methods: This prospective interventional case series included 110 eyes of 107 patients with anterior corneal pathology who underwent DALK, including 78 with keratoconus. Outcome measures included the rate of bubble formation, rate of completing DALK, bubble types, complications, and visual and keratometric parameters. Results: Intrastromal air injection was attempted in 109 eyes, and the air bubble was achieved in 93 eyes (85.3%). Intrastromal 2% methylcellulose injection was attempted in 9 eyes, after unsuccessful air bubble formation, and the viscobubble was achieved in 7 eyes (77.8%). Manual layer-by-layer dissection was performed in 8 eyes. Bubble formation was reached in 100 eyes (90.9%). Overall, 105 eyes (95.5%) achieved DALK. Air bubble occurred as type 1 (white margin) in 96.6% of the cases and as type 2 (clear margin) in 3.4%. There was a statistically significant improvement in all visual and keratometric parameters analyzed. Macroperforations converted to penetrating keratoplasty occurred in 5 eyes (4.5%) and microperforations in 12 (10.9%). There were significantly higher rates of perforation when a bubble was not achieved (P 0.018) and when it was achieved as type 2 (P 0.033). Interface haze occurred in 5 eyes (4.5%) and stromal rejection in 11 (10.0%). A short learning curve was observed for air bubble formation. Conclusions: Bubble formation, especially type 1, is the key to decrease the risk of perforation in DALK. The pachy-bubble was safe, effective, and reproducible in promoting DALK with air bubble and viscobubble formation with a short learning curve.