In vitro study of air bubble dynamics following pneumodissection of donor corneas and relationship of air bubble pattern with a peripheral paracentesis incision.

Abstract

To study various types of morphological patterns of the air bubble and their relation to a peripheral paracentesis after air injection in corneal stroma in vitro experiment. Air was injected into the donor corneas from the endothelial side and pattern was noted. Four different scenarios were created, namely (a) air injection into the deep stroma (n=11), (b) air injection into the superficial stroma (n=3), (c) air injection into the deep stroma after making a peripheral incision internal to the trabecular meshwork region that simulated an anteriorly placed paracentesis incision, with the site of air injection within a clock hour of the peripheral incision (n=7) and (d) air injection into the deep stroma after making a peripheral incision, the site of air injection being 180° away from the peripheral incision site (n=3). Air injection at deep posterior stroma resulted in the formation of type-1 and type-2 bubbles, type 2 began from the periphery and followed the type-1 bubble pattern in majority of the donor corneas. The type-1 pattern was noted as a bubble in the central part of the donor disc that did not reach the peripheral extent of the cornea. The type-2 pattern was a bubble that started at the peripheral cornea and expanded but was limited by the limbus circumferentially. With a full-thickness peripheral incision and air injection in the same clock hour of the incision, only a type-1 bubble pattern was noted with air leakage from the site of the incision. The results of the study corroborate with the clinical observations made during deep lamellar keratoplasty (DLK). The placement of the paracentesis has a bearing on the pattern of the air bubble and can be used to an advantage during DLK surgery.