JAN 07, 2013
This laboratory study investigated the pressure required to rupture the posterior lamella during big-bubble deep anterior lamellar keratoplasty (DALK).
The investigators performed the procedure on donor corneoscleral discs mounted on an artificial anterior chamber. Once the anterior lamella was removed, the chamber was connected to a mercury manometer. The pressure inside the chamber was increased until rupture occurred or the manometer reached its measurement limit.
The deep lamella ruptured at 252 mmHg in one cornea, at 270 mm Hg in another, and had not ruptured at 300 mmHg (the upper limit of the manometer) in the remaining 18 donor corneas. The ruptures occurred across the center of the posterior lamella in the samples that did rupture.
They conclude that the posterior lamella of big-bubble DALK probably confers significant structural integrity on the globe. The authors also say it is possible that a small amount of stroma remaining after big-bubble DALK could account for the rupture pressures seen in the study and be beneficial in DALK.
They note a limitation of the study is that it was performed on donor corneoscleral discs rather than whole eyes, which may have altered the rupture pressure.