Purpose: To compare post-operative pain perception using bandage contact lens (BCL) stored at 2-8 degrees C (Cold BCL, CL-BCL) or room temperature (23 - 25 degrees C, RT-BCL) after photorefractive keratectomy (PRK) or corneal collagen-crosslinking (CXL) and determine status of nociception associated factors.Methods: In this prospective interventional study, 56 patients undergoing PRK for refractive correction and 100 keratoconus (KC) undergoing CXL were recruited following approval from the institutional ethics committee with informed consent. Patients undergoing bilateral PRK received RT-BCL on one eye and CL-BCL on the other. Pain was graded by Wong-Baker scoring on the first post-operative day (PoD1). Expression of transient receptor potential channels (TRPV1, TRPA1, TRPM8), calcitonin gene-related peptide (CGRP) and IL-6 was measured in cellular content from used BCLs collected on PoD1. Equal number of KC patients received RT-BCL or CL-BCL post-CXL. Pain was graded by Wong-Baker scoring on PoD1.Results: Pain scores on PoD1 were significantly (P < 0.0001) reduced in subjects receiving CL-BCL (Mean +/- SD: 2.6 +/- 2.1) compared to RT-BCL (6.0 +/- 2.4) post-PRK. 80.4% of subjects reported reduced pain scores with CL-BCL. 19.6% reported no change or increased pain scores with CL-BCL. TRPM8 expression was significantly (P < 0.05) increased in BCL of subjects reporting reduced pain with CL-BCL compared to those who did not. Pain scores on PoD1 were significantly (P < 0.0001) reduced in subjects receiving CL-BCL (3.2 +/- 2.1) compared to RT-BCL (7.2 +/- 1.8) post-CXL.Conclusion: The simple approach of using a cold BCL post-operatively substantially reduced pain perception and could overcome post-operative pain-related limited acceptance of PRK/CXL.
