Complications of Mersilene sutures in penetrating keratoplasty.

BACKGROUND: After penetrating keratoplasty, many corneal surgeons adjust sutures to reduce astigmatism and then leave the sutures in place indefinitely. Nylon sutures can hydrolyze and break years after surgery. In a series of human penetrating keratoplasties, we studied the use of polyester (Mersilene) sutures that do not hydrolyze. METHODS: We performed two prospective studies of polyester (Mersilene) sutures in human penetrating keratoplasty done by one surgeon. Study I was a randomized comparison of combined running and interrupted Mersilene and nylon sutures in 45 consecutive eyes. Study II was a case series of single running Mersilene suture with postoperative adjustment of suture tension to manage astigmatism in 23 consecutive eyes. We evaluated the performance of the suture and the control of astigmatism. RESULTS: The interrupted running suture study demonstrated that interrupted Mersilene sutures were 5.5 times more likely to have handling-related complications than nylon interrupted sutures (p = .01); in addition, they were three times as likely to have tissue-related complications as nylon (p = .16). The running suture study demonstrated an unacceptable complication rate of 69% when Mersilene was used as a single adjustable running suture. At 6 months postoperatively, the median refractive astigmatism for the adjustable cases was 3.37 diopters (mean, 4.03 +/- 2.37 D). Eyes with significant suture-related complications were 2.85 times more likely to have greater than 4.00 D of refractive astigmatism than were eyes without suture-related complications. CONCLUSIONS: Mersilene is an undesirable suture for use in penetrating keratoplasty.

Inadequacy of a polyester (Mersilene) suture for the reduction of astigmatism after penetrating keratoplasty.

Through two prospective studies, we evaluated the use of polyester (Mersilene) sutures in penetrating keratoplasty. Study 1 was a randomized comparison of combined running and interrupted Mersilene and nylon sutures (n = 45). Study 2 was a case series of single running Mersilene with postoperative adjustment of suture tension to manage astigmatism (n = 23). Study 1 demonstrated that Mersilene interrupted sutures were 5.5 times more likely to have handling-related complications compared to nylon (P = 0.01); in addition, they were 3 times as likely to have tissue-related complications as nylon interrupted sutures (P = 0.16). Study 2 demonstrated a complication rate of 69% when Mersilene was used as a single adjustable running suture. At 6 months postoperatively, the median refractive astigmatism for the adjustable cases was 3.37 D (mean, 4.03 +/- 2.37 D). Eyes in Study 2 with significant suture-related complications were 2.85 times more likely to have greater than 4 D of refractive astigmatism than were eyes without suture-related complications. We concluded that Mersilene is an undesirable suture for use in penetrating keratoplasty.

The contribution of cell-to-cell fusion to the ordered structure of the crystalline lens.

In this report we demonstrate that the extensive intercellular network of communication within crystalline lenses (lens fiber cell gap junctions and cell-to-cell fusion between fiber cells) plays a key role in lens development and growth. We describe how the irregular shaped fusion zones can contain "positional information" to spur "intercalary growth" in the lens to bring about the highly ordered arrangement of fiber cells into radial cell columns and intricate suture patterns necessary to insure lens transparency.

Comparison of the effects of argon fluoride (ArF) and krypton fluoride (KrF) excimer lasers on ocular structures.

We evaluated the effects of argon fluoride (ArF) and krypton fluoride (KrF) excimer lasers on ocular structures. We produced corneal incisions, optical iridotomy, capsulotomy, and retinotomy with these lasers. Incisions produced with ArF showed sharply defined borders with minimal coagulative effects to the adjacent structures. Cuts created with KrF showed coagulative necrosis of the wound edges ranging from two to five um in width. From our study it appears that ArF has photoablative action and KrF has a predominantly photoablative action with minimal photocoagulative effect on the tissue.

Sutures of the crystalline lens: a review.

The sutures of the crystalline lens have previously been studied by light microscopy (LM). While the gross suture patterns (umbilical, line, y-shaped and star) of lenses are readily visualized by LM, fiber cell shape, curvature, length and the morphology of fiber cell ends cannot be adequately resolved by this technique. We have used scanning electron microscopy (SEM) to examine the sutures of crystalline lenses. SEM has revealed that in lenses with line, y-shaped or umbilical sutures, the anterior and posterior ends of fiber cells curve away in opposite directions from the polar axis of the lens before interlocking at suture branches. The degree of curvature decreases as a function of the number of suture branches. This relationship was not resolved by LM. SEM has revealed that the relationship of fiber cell taper to suture type was underestimated by previous LM studies. The reduction in fiber cell width from the equator to the sutures is 3:1 and 2:1 respectively, in lenses with line and y-shaped sutures. Furthermore, in lenses with star sutures, fiber cells are flared (1:1.7) rather than tapered, a fact not reported by previous LM studies. SEM also revealed that the offsetting of anterior and posterior suture branches does not result in equal fiber cell length in any growth ring as reported by LM studies. Rather, fiber cell length in any one growth ring varies as a sine wave function according to fiber cell location at the equator. Furthermore, the range of fiber cell length decreases as a function of the number of suture branches. Finally, SEM has revealed that the distal ends of fiber cells are expanded in both width and thickness prior to interlocking at suture branches and that these ends overlap rather than simply abut end-to-end to form a three dimensional suture plane extending down from the lens surfaces to the primary fiber cell mass.