Effect of Intrastromal Air or Hydro–Injection on Apoptosis of Keratocytes

Abstract

Purpose: : Deep lamellar keratoplasty (DLKP) needs air–guided or hydro–guided deep stromal detachment. The air or hydration can propagate the periphery of the remaining cornea with possible effect on peripheral wound heal. Therefore we are investigating the effect of intrastromal air– or hydro–injection on apoptosis of corneal keratocytes.

Methods: : Twelve right eyes of New Zealand White rabbits were divided into Air–injected (n=6) and Hydro–injected group (n=6). Fellow eyes were served as a control. Air or balanced salt solution (BSS) was injected into deep corneal stroma at paracentral area to propagate in nearly entire cornea. To reduce the intraocular pressure, anterior chamber paracentesis was performed. They were sacrificed 4 hours (n=6) and 24 hours (n=6) after surgery. Central cornea buttons were retrieved to stain with H&E and TUNEL (Apoptag^®, Chemicon). The mean number of apoptotic keratocytes was counted in 5 consecutive high power field (HPF).

Results: : The mean number of TUNEL–positive cells at 4hours was 12.85 ± 7.25/HPF and 0.25 ± 0.44/HPF in air–injected and hydro–injected eyes, respectively, and then reduced to 6.25 ± 4.02/HPF and 0.15 ± 0.37/HPF in each air–injected and hydro–injected eyes after 24 hours. The Air–injected group showed significantly more TUNEL–positive cells compared with the hydro–injected or control group till 24 hours (p=0.001, p=0.001, Mann–Whitney U test).

Conclusions: : Intrastromal air injection induces significant apoptosis of keratocytes suggesting some damages in peripheral cornea when used in DLKP.

Keywords: cornea: stroma and keratocytes • apoptosis/cell death