Abstract
Purpose: :
To evaluate hyaluronidase in modulating the lens regenerative process following endocapsular lens extraction in New Zealand white rabbits when hyaluronic acid is used as an internal scaffold to control lens epithelial cell proliferation and differentiation.
Methods: :
Endocapsular lens extraction by phacoemulsification and irrigation/aspiration of the lens through a 2–3 mm capsulorrhexis was performed in 6 eyes of 3 New Zealand (NZ) white rabbits, age 5 months, wt 3.0 kg. Following removal of the lens, a high–viscosity hyaluronic acid, which is known to promote wound healing, was injected into the capsule bag and a collagen patch was placed inside the capsulorrhexis and brought up against the capsulotomy with an air bubble in the bag. At one week and one month postoperatively, hyaluronidase was injected intralenticularly into the hyaluronic acid scaffold. The animals were followed postoperatively by slit lamp biomicroscopy and photography.
Results: :
Following the hyaluronidase injection at day 6, the capsule bag was noted to be flat in 2 of the 3 eyes receiving the intralenticular injection and as lens regrowth progressed the capsule bag had a normal spherical shape except in one eye with an adhesion at the capsulotomy site. In the one–month group, the regenerated lens remained spherical through day 91. New lens regrowth filling 5 to 20% of the capsule bag or retained cortical material was first noted at day 6 in the one–week group and at day 27 in the one–month group. Lens regrowth gradually progressed in both groups. Full lens regrowth was first noted at day 35 in 1 of the one–week eyes and at day 41 in all eyes. Initially, lens regrowth progressed from the periphery toward the center fairly uniformly around the Restylane center. Following intralenticular hyaluronidase injection, the regenerating lens collapsed centrally with irregular alignment of lens fibers giving the nucleus a faint star shape. Lens nuclear clarity was slightly better in the one–week group compared to the one–month group. The lens cortex had fairly good clarity and structure with occasional vacuoles and/or retained Restylane in both groups
Conclusions: :
Hyaluronidase was effective in dissolving retained Restylane following endocapsular lens extraction in 5–month–old NZ white rabbits. The regenerating lens tended to collapse centrally following the intralenticular hyaluronidase injection. As lens regeneration progressed, the irregular alignment of central fibers resulted in a spherical regenerated lens with a nuclear star shape opacity of poor clarity and a fairly normal cortex with good structure and clarity.
Keywords: regeneration • crystalline lens • wound healing