Qualitative holographic-interferometric analysis of T-incisions of different length in vitro-A preliminary report

Concepts including the length of T-incisions are mainly based on empirical evaluation of the surgeons. We report on a holographic interferometric study of the effects of straight T- incisions of 5 mm, 10 mm, and 15 mm length using double-exposure holographic interferometry. A new classification of the central holographic interferometric fringe pattern including cross-like, parallel and convex fringes allows an objective qualitative analysis of 48 holographic interferograms of the corneas of six bovine eyes. The intraocular pressure is 1340 Pa with 10 Pa and 20 Pa pressure increase. T-incisions of 5 mm length of incision (incision depth 95%) change the holographic interferometric fringe pattern completely. An increase to 10 mm length of incision results in a change of holographic fringe pattern in 50% of the cases. With 15 mm length of incision only two types of holographic interferometric fringe pattern of the cornea can be seen: parallel fringes and irregular fringes indicating an instability of the cornea. This might be a reason for paradox flattening of the cornea in the unincised meridian.