Relative strength of scleral corneal and clear corneal incisions constructed in cadaver eyes

Abstract

Square scleral corneal, square clear corneal, and rectangular clear corneal incisions were constructed in six cadaver eyes that had no previous intraocular surgery. The 3.2 mm or smaller wounds had sutureless closures. To determine their relative abilities to resist leakage and iris prolapse, eyes were tested at external pressures of up to 525 pounds per square inch (psi) at one of two intraocular pressure (IOP) ranges: 10 to 15 mm Hg or 20 to 25 mm Hg. The square scleral corneal (3.2 mm x 3.2 mm) and square clear corneal wounds (3.2 mm x 3.2 mm, 2.0 mm x 2.0 mm, 1.0 mm x 1.0 mm) withstood external pressure without effect at both IOP ranges, up to the maximum 525 psi. This level of external pressure was far greater than pressures withstood by rectangular clear corneal wounds, especially the wound usually constructed in clinical practice (3.2 mm x 2.0 mm), which leaked and demonstrated iris prolapse at 13 psi at the lower IOP. The square clear corneal wounds that were stable at 525 psi, however, are either clinically impractical (visual axis encroachment from 3.2 mm x 3.2 mm wound) or not technologically feasible until the size of phacoemulsification tips and intraocular lenses can be further reduced. Thus, of the procedures for small incision cataract surgery presently in use, the square scleral corneal incision with 1.5 mm internal corneal lip appears to offer greater stability and safety than the conventional rectangular clear corneal incision (3.2 mm x 2.0 mm).

Clear corneal incision leakage after phacoemulsification––detection using povidone iodine 5%

“…A square wound affords greater stability than a rectangular wound [9]. In this study, a square side-port corneal incision was noted to rarely leak, even without hydration.…”

Comparison of stromal hydration techniques for clear corneal cataract incisions: Conventional hydration versus anterior stromal pocket hydration

“…[5][6][7][8][9][10][11][12][13][14] Many consider stromal hydration to be an important adjunct that may be used to improve wound integrity in the early postoperative period, with both in vitro and in vivo studies suggesting a possible benefit. 5,6,9,10,12,13 Wong A developed a novel modification of the CCI that provides an enhanced effect of stromal hydration and wound sealing. To our knowledge, this study is the first prospective trial comparing anterior stromal pocket hydration and conventional hydration and shows a significant advantage for this modified technique in preventing wound leak caused by direct pressure to the area of the incision, particularly the posterior lip of the CCI.…”

In vivo architectural analysis of 3.2 mm clear corneal incisions for phacoemulsification using optical coherence tomography

“…[31][32][33][34] However, Kohnen and Kaspar 31 also showed minimum enlargement (2.8%) when an SA60 IOL was implanted with a Monarch II/cartridge C, as done in our study. Ernest et al 35,36 and Mackool and Russell 37 found incision size has a direct impact on the strength and stability of CCIs and, thus, on the risk for endophthalmitis. [35][36][37] All our incisions were located superiorly.…”