LASIK Surgery Can Alter Corneal Epithelial Dendritic Cells 12 Months Postoperative

Corneal epithelial dendritic cell (CEDC) density and morphology may be altered after LASIK surgery, even 12 months later, according to a study published in Acta Ophthalmologica.

Researchers reviewed 20 patients who underwent LASIK at the University of New South Wales in Australia 12 to 16 months previously as well as 20 patients who served as a healthy control group. Clinicians imaged the right eye of each participant using a laser scanning in vivo confocal microscopy. The researchers used a study-specific subjective standardized clinical grading system based on cell size and density, and dendrite features, to demonstrate evidence of LASIK-associated CEDC changes. The researchers also evaluated patients for tear neuropeptide make up.

Based on 80 images, intra- and inter-observer CEDC morphology grading system outcomes were high (k range, 0.82-0.97).

A total of 11 LASIK and 19 control participants had observable CEDC in their images. Compared with controls, the LASIK recipients had decreased CEDC densities (median, 5 vs 21 cells/mm²; P =.01), more CEDCs had dendrites (82% vs 32%; P =.02), and more had thick dendrites (73% vs 21%; P =.01), respectively. No group differences were observed for CEDC body size (P =.36) or the presence of CEDCs with long dendrites (P =.42).

Stratified by the presence of nerves, both CEDCs with and without nerves had more dendrites (both P ≤.04) and had more thick dendrites (both P ≤.03) in the post-LASIK group compared with controls.

The densities of CEDCs (r, 0.40; P =.01) and CEDCs without nerves (r, 0.49; P =.01) were significantly correlated with tear substance P. 

Stratified by the presence of CEDCs with and without long dendrites, participants without long dendrites on CEDCs (P =.04) and CEDCs with nerves (P =.004) had significantly higher tear substance P than those with long dendrites.

The CEDCs with nerves and a long dendrite phenotype had increased corneal nerve interconnections than cells without a long dendrite phenotype (P =.03).

The major limitation of this study was that the CEDCs were graded from 2-dimensional images, which did not reflect the three-dimensional corneal epithelium structure.

“This study established a novel comprehensive morphological grading system for CEDC that showed excellent reliability. Although density of CEDC was lower in the post-LASIK participants, a higher proportion

of CEDC with dendrites, and thick dendrites, was found, consistent with these cells being more migratory post-LASIK,” the researchers explain. “In addition, this study found substance P and reinnervation associated with CEDC density and morphology for the first time. Since substance P showed to be associated with greater symptoms and corneal reinnervation, it provides useful insights into the possible roles of CEDC in corneal reinnervation and neurogenic inflammation post-LASIK.”