Pain and Its Determinants in Photorefractive Keratectomy

Cold bandage contact lens use reduces post-photorefractive keratectomy or corneal collagen-crosslinking pain perception in patients

Purpose

To compare post-operative pain perception using bandage contact lens (BCL) stored at 2-8°C (Cold BCL, CL-BCL) or room temperature (23 - 25°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.

Preoperative Predictors for Acute Pain After Photorefractive Keratectomy

PURPOSE

The aim of this study was to identify preoperative predictors for the occurrence of early severe postoperative pain in patients undergoing photorefractive keratectomy (PRK). The implementation of preoperative screening methods may facilitate more specific or aggressive pain therapies specifically targeted to individuals at a high risk of experiencing severe postoperative pain.

METHODS

This was exploratory research that included patients who underwent PRK. Before PRK, patients were administered a sociodemographic questionnaire, the Pain Catastrophizing Scale, and the State-Trait Anxiety Inventory and underwent corneal sensitivity and conditioned pain modulation (CPM) tests. Post-PRK pain was assessed using a pain intensity visual analog scale (VAS), and the short-form McGill Pain Questionnaire (SF-MPQ) was completed 21 days before PRK and 1, 24, 48, and 72 hours after PRK. Spearman correlations were calculated for pain scores and preoperative predictors.

RESULTS

This research included 34 eyes of 34 patients. Preoperative corneal sensitivity was positively correlated with post-PRK pain scores as assessed by VAS and SF-MPQ (rho = 0.39 and rho = 0.41, respectively, P < 0.05). No correlations were found between Pain Catastrophizing Scale, State-Trait Anxiety Inventory, and CPM scores and post-PRK pain scores (P > 0.05).

CONCLUSIONS

Abnormal presurgical corneal sensitivity was a protective marker for severe pain after PRK, while scores as assessed by VAS and SF-MPQ and CPM were not related to postoperative pain.

Update on Pain Management After Advanced Surface Ablation

PURPOSE

To provide an update for postoperative pain control strategies to help ophthalmic surgeons establish a more effective management plan for patients who underwent advanced surface ablation surgeries.

METHODS

Google Scholar, Scopus, ScienceDirect, and PubMed were the main resources used to search the medical literature.

RESULTS

The postoperative cornea's healing process is accompanied by intense pain as the chief complaint in the first days after the operation. Several strategies were developed to relieve postoperative pain after surface ablation procedures. These strategies included different preoperative, intraoperative, and postoperative methods. Considering the preoperative demographic and emotional factors, underlying dry eye, alternative epithelial removal techniques, bandage contact lenses, and topical or oral therapeutic agents are some examples of postoperative pain treatments after surface ablation procedures.

CONCLUSIONS

The current review revealed that despite the development of numerous protocols to relieve postoperative pain following surface ablations, the best approach could be a combination of different strategies. In practice, no validated and standardized strategy is available for total elimination of postoperative pain following advanced surface ablation surgeries. [J Refract Surg. 2021;37(11):782-790.].

Ascorbic acid versus placebo in postoperative lid edema postphotorefractive keratectomy: A double-masked, randomized, prospective study

INTRODUCTION

Photorefractive keratectomy (PRK) is a proper type of refractive surgery used to remodel corneal stroma to compensate refractive errors. Corneal haze was reported as one of the side effects in several studies. This study was conducted for investigation of the effect of preventive effect of Vitamin C on eyelid edema, corneal haze, corneal epithelial healing, mitigation of pain, and epiphora.

MATERIALS AND METHODS

This study has been performed as a double-blind clinical trial on 51 patients who underwent PRK surgery. The patients were randomly divided into two groups as follows: case group who received oral ascorbic acid 250 mg once daily for 7 days and control group that took placebo 3 days before and 4 days after the surgical operation. The patients underwent a surgical operation on day 0. Then, the following factors were evaluated as the main outcome: postoperative lid edema, pain, corneal haze, and corneal reepithelialization.

RESULTS

The mean age of the patients was 28.52 ± 8.05 years. There was no statistically significant difference in the primary outcome of the subjective pain scores along with corneal haze and corneal reepithelialization between the treatment and placebo groups at any point during the postoperative period; however, there was a statistically significant difference and trend for lower lid edema in the ascorbic acids group on postoperative day 1 (P < 0.05).

CONCLUSION

This study demonstrates that ascorbic acid may provide an alternative or add-on option for lid edema relief after PRK.