Evaluation of early postoperative ocular pain after photorefractive keratectomy and corneal crosslinking

Preservative-Free Topical Anesthetic Unit-Dose Eye Drops for the Management of Postoperative Pain Following Photorefractive Keratectomy

INTRODUCTION

Ocular pain is a common complication following photorefractive keratectomy (PRK). The level of patient satisfaction with current pain control strategies is not high. This study aims to assess the efficacy and safety of a novel regimen of preservative-free oxybuprocaine hydrochloride 0.4% unit-dose eye drops for post-PRK pain control.

METHODS

In a contralateral eye study, 144 eyes of 72 patients who underwent bilateral transepithelial PRK (TransPRK) were stratified into experimental and control groups. The experimental group received preservative-free oxybuprocaine hydrochloride 0.4% unit-dose eye drops five times daily postoperatively until complete epithelial healing, while the control group received sodium hyaluronate 0.2% instead. The main outcome measures were pain scores assessed by the verbal rating scale and visual analogue scale (VRS, VAS), the corneal epithelial defect (CED) area, epithelial healing duration evaluated by slit-lamp biomicroscopy and anterior segment optical coherence tomography (AS-OCT), and endothelial cell density (ECD) measured before and 1 month after surgery.

RESULTS

Pain scores assessed by VRS and VAS were significantly lower in the experimental group 8 h after surgery, and 1, 2, and 3 days postoperatively (P < 0.001). The mean CED area showed no significant differences between the two groups at different follow-ups (P value > 0.05). The corneal epithelial healing had a mean duration of 3.32 ± 0.47 days in both studied groups and was parallel in both eyes of each patient. In each group, 49 eyes (68%) and 72 eyes (100%) had a fully epithelialized surface on the third and fourth postoperative days, respectively. No significant changes were observed in the mean ECD 1 month following surgery in both groups (P value > 0.05).

CONCLUSION

Preservative-free oxybuprocaine hydrochloride 0.4% unit-dose eye drops are effective and safe in controlling early postoperative pain following TransPRK. The availability of the single-dose unit preparation can overcome the problem of topical anesthetic abuse.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05733741.

Topical analgesics for acute corneal pain: current options and emerging therapeutics

Acute corneal pain is a common complaint that causes significant distress to patients and continues to challenge therapeutic avenues for pain management. Current topical treatment options have marked limitations in terms of both efficacy and safety, thus often prompting the adjunctive use of systemic analgesics, including opioids. In general, there have not been extensive advancements in pharmacologic options for the management of corneal pain over the past several decades. Despite this, multiple promising therapeutic avenues exist which hold the potential to transform the ocular pain landscape, including druggable targets within the endocannabinoid system. This review will summarize the current evidence base for topical nonsteroidal anti-inflammatory drugs, anticholinergic agents, and anesthetics before focusing on several potential avenues in the setting of acute corneal pain management, including autologous tear serum, topical opioids and endocannabinoid system modulators.

Intracanalicular dexamethasone insert for post-corneal crosslinking inflammation and pain: the LINK study

PURPOSE

To compare the efficacy of an intracanalicular dexamethasone insert with tapered topical steroid over 28 days after corneal cross-linking (CXL).

SETTING

Single private practice, outpatient setting.

DESIGN

Prospective observational randomized study.

METHODS

This prospective randomized study investigated the efficacy of a dexamethasone intracanalicular insert on post-CXL pain and inflammation in progressive keratoconus patients. 20 patients (40 eyes) were enrolled; half were randomized to the dexamethasone intracanalicular insert group; half were prescribed a 28-day topical tapering steroid regimen. All patients were evaluated for pain scores, rate of re-epithelialization, ease of the post-CXL regimen, and need for rescue pain medication after standard bilateral epithelium-off CXL on postoperative day (POD) 1, POD3, and POD4 to 7, as well as postoperative week (POW) 1, POW2, POW3, and POW4.

RESULTS

20 patients (40 eyes) underwent standard-of-care epithelium-off bilateral CXL for progressive keratoconus. 10 patients were randomized to receive prednisolone eyedrops on a tapering schedule after CXL; 10 patients received dexamethasone intracanalicular inserts at the time of CXL. Regardless of the postoperative steroid regimen, there was no significant difference in the rate of re-epithelialization or use of rescue pain medication between groups. There was a nominal, however, statistical difference in pain scores between groups, favoring prednisolone eyedrops. Both groups stated no difficulty in following postoperative regimens. There were no adverse events noted in relation to treatment or the CXL procedure.

CONCLUSIONS

Using a dexamethasone insert to alleviate pain and inflammation can be considered as a safe and efficacious part of a post-CXL regimen.

Topical Ocular TRPV1 Antagonist SAF312 (Libvatrep) for Postoperative Pain After Photorefractive Keratectomy

Purpose

Evaluation of safety and efficacy of topical ocular SAF312 (Libvatrep) in post-photorefractive keratectomy (PRK) pain.

Methods

In this placebo (vehicle)-controlled, participant- and investigator-masked study, 40 participants were randomized (1:1) to two treatment sequences in a bilateral PRK crossover design (SAF312 2.5% followed by vehicle [or vice versa], one eye drop, four times daily for 72 hours after PRK). Primary endpoints were visual analog scale (VAS) pain scores at 6 hours after first drop of study drug and average VAS scores over 0 to 12 hours postoperatively. Secondary endpoints included postoperative oral rescue medication (ORM) use and adverse events (AEs).

Results

All 40 participants completed the study. Both primary endpoints were met; mean difference in VAS pain scores between SAF312- and vehicle-treated eyes was -11.13 (P = 0.005, -25%) at 6 hours postoperatively and -8.56 (P = 0.017, -22%) over 0 to 12 hours. Mean VAS pain scores with SAF312 were consistently lower than with vehicle from 1 hour postoperatively up to 30 hours (P ≤ 0.10 observed in 8/11 time points). Less ORM was taken with SAF312 up to 0 to 72 hours postoperatively, with a trend of fewer participants taking ORM at 0 to 24 hours postoperatively with SAF312 versus vehicle. No serious AEs were reported. All ocular AEs were mild and transient, and none were drug related. SAF312-treated eyes showed no delay in wound healing and had a lower grade 4 conjunctival hyperemia 24 hours postoperatively versus vehicle-treated eyes.

Conclusions

SAF312 was well tolerated and effective in reducing ocular pain post-PRK.

Translational Relevance

Topical SAF312 presents a new therapeutic option for patients undergoing PRK.

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.

Pain mechanisms and management in corneal cross-linking: a review

Though corneal collagen cross-linking (CXL) is an increasingly available and effective treatment for keratoconus, few reports have considered its impact on pain-related physiology in depth. This comprehensive narrative review summarises mechanisms underlying pain in CXL and clinical care possibilities, with the goal of future improvement in management of CXL-related pain. Postoperative pain associated with CXL is largely due to primary afferent nerve injury and, to a smaller extent, inflammation. Chronification of pain after CXL has not been reported, even as long-term nerve damage without regeneration following standard CXL treatment is frequently observed. The lack of pain chronification may be due to the minimally invasive nature of the procedure, with its rapidly recovering superficial corneal wound, and to the positive anti-inflammatory changes of the tear film that have been described after CXL. Different CXL approaches have been developed, with the transepithelial epithelial-on technique (epi-on) associated with less postsurgical pain than the gold standard, epithelial-off technique (epi-off). After the first few days, however, the difference in pain scores and need for analgesics between epi-on and epi-off disappear. Patients experience relatively high-intensity pain the first few days post-CXL, and many strategies for acute pain control following CXL have been studied. Currently, no method of pain management is considered superior or universally accepted. Acute pain following CXL is a recognised and clinically significant side effect, but few CXL studies have systematically investigated postoperative pain and its management. This review aims to improve patient pain outcomes following this increasingly common procedure.

Epithelial Flap Corneal Cross-linking

PURPOSE

To compare standard epithelium-off corneal cross-linking (standard Epi-Off CXL) to corneal cross-linking with an epithelial flap (Epi-Flap CXL).

METHODS

Patients who had undergone sequential bilateral CXL for progressive keratoconus were included in this comparative interventional case series. One eye was treated with the Epi-Off CXL technique and the fellow eye with the Epi-Flap CXL technique. Postoperative pain was measured using the Verbal Rating Scale and corneal densitometry using a Scheimpflug camera. Sex, age, corrected distance visual acuity, keratometry, and corneal thickness were also recorded.

RESULTS

Twenty-four eyes of 12 patients with keratoconus with a mean age of 27.15 ± 5.15 years were included. The Verbal Rating Scale scores were significantly lower in patients who had Epi-Flap CXL on the first (1.00 [interquartile range (IQR): 0.00 to 1.00] vs 3.00 [IQR: 3.00 to 3.75], P = .01) and third (0.00 [IQR: 0.00 to 1.00] vs 1.00 [IQR: 0.00 to 1.00], P = .01) postoperative day compared to the Epi-Off CXL group. No pain was observed in both groups after the third day. After 12 months, the Epi-Flap CXL group showed significantly less anterior corneal haze (measured as corneal densitometry) compared to the patients treated with Epi-Off CXL (P = .01). Both groups demonstrated stability of keratometry and corneal thickness at 12 months after CXL (P < .01).

CONCLUSIONS

Epi-Flap CXL is associated with less postoperative pain and anterior stromal haze in patients undergoing CXL for progressive keratoconus with no loss of efficacy. [J Refract Surg. 2021;37(11):741-745.].

Intraoperative Pain Sensation During Cataract Surgery: Why Does Timing Matter?

Purpose: To investigate whether timing influences pain perception during cataract surgery and to investigate the possible mechanisms.Methods: Patients scheduled for cataract surgery both in the morning and afternoon were consecutively enrolled. Questionnaires to evaluate anxiety, including the Simplified State-Trait Anxiety Inventory, Amsterdam Preoperative Anxiety and Information Scale, and a visual analogue scale (VAS) for anxiety, were completed preoperatively, whereas a VAS for pain and the Wong-Baker FACES® Pain Rating Scale questionnaire were completed after surgery. Preoperative blood pressure and heart rate were recorded. Blood samples were acquired before surgery, and plasma cortisol, adrenocorticotropic hormone, adrenalin, and noradrenalin were tested.Results: Fifty-five patients underwent uneverntful cataract surgery (28 in the morning and 27 in the afternoon) were included in the final analysis. Greater intraoperative pain perception during cataract surgery was reported in the afternoon than in the morning. Overall anxiety levels were significantly higher in the afternoon. Plasma adrenalin levels were significantly higher in the afternoon. Cortisol levels were higher in the afternoon. Preoperative anxiety levels were closely related to intraoperative pain perception. Both adrenalin and cortisol correlated positively with preoperative anxiety, but only adrenalin correlated significantly with the pain scores.Conclusions: Patients undergoing cataract surgery in the afternoon showed more preoperative anxiety, which may have increased their relevant stress hormones. Both the patient's emotional state and hormone levels may together aggravate his/her perceived pain in the afternoon. Monitoring preoperative anxiety levels, blood pressure, and heart rate should help to identify patients at higher risk of perceived intraoperative pain.Clinical trial registration:Trial registration number: NCT02182921Registration site: clinicaltrials.gov.