Yao X, Xu J
Department of Ophthalmology, Medical College of Jinan University, Guangzhou.
Zhonghua Yan Ke Za Zhi. 1996 Mar;32(2):147-9.
To assess the effect of epikeratophakia (EKP) on corneal nerve regeneration and the recovery of corneal sensitivity.
36 adult rabbits underwent epikeratophakia with either 0.2 mm or 0.3-0.35 mm circular trephination. A histochemical technique (acetylcholine esterase staining) was used to investigate the process of corneal nerve regeneration, and the recovery of corneal sensitivity was determined in 36 rabbits at various intervals after EKP.
The corneal sensory nerves began to regenerate just peripheral to the host-donor interface 3 weeks following EKP, the nerve fibers traveled toward the stroma of the lenticules at 2 months, and formed a sparse subepithelial plexus at 8 months after surgery. A relative hyposthesia was found in the central zone of the lenticule when compared with its peripheral zone 4 months postoperatively. The sensitivity of the central zone remained lower at 5-8 months after EKP though it had remarkably increased. The density of re-innervated fibers was higher in the shallow incision than that in deeper one.
It is suggested that the factors affecting the corneal innervation and the recovery of corneal sensitivity following EKP include; (1) the scar formation as a barrier; (2) the adaptation to the micro-environment around the lenticule; and (3) the depth of trephine cut. Therefore, a 0.2-0.25 mm depth of trephine incision is advantageous to the lamellar dissection, graft suturation and corneal nerve regeneration.
