Pregabalin Failed to Prevent Dry Eye Symptoms after Laser-Assisted in Situ Keratomileusis (LASIK) in a Randomized Pilot Study

Evaluating the efficacy and safety of therapeutic interventions for corneal neuropathy: A systematic review

Corneal neuropathy involves corneal nerve damage that disrupts ocular surface integrity, negatively impacting quality-of-life from pain and impaired vision. Any ocular or systemic condition that damages the trigeminal nerve can lead to corneal neuropathy. However, the condition currently does not have standardized diagnostic criteria or treatment protocols. The primary aim of this systematic review was to evaluate the efficacy and safety of interventions for treating corneal neuropathy. Randomized controlled trials (RCTs) that investigated corneal neuropathy treatments were eligible if the intervention(s) was compared to a placebo or active comparator. Comprehensive searches were conducted in Ovid MEDLINE, Ovid Embase and clinical trial registries from inception to July 2022. The Cochrane Risk-of-Bias 2 tool was used to assess study methodological quality. Certainty of the body of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Overall, 20 RCTs were included. Evaluated interventions comprised regenerative therapies (n=6 studies), dietary supplements (n=4), anti-glycemic agents (n=3), combination therapy (n=3), supportive therapies (n=2) and systemic pain pharmacotherapies (n=2). Nine RCTs were judged at high risk of bias for most outcomes. Definitions for corneal neuropathy in the populations varied substantially across studies, consistent with lack of consensus on diagnostic criteria. A diverse range of outcomes were quantified, likely reflecting absence of an agreed core outcome. There was insufficient evidence to draw definitive conclusions on the efficacy or safety of any intervention. There was low or very low certainty evidence for several neuroregenerative agents and dietary supplements for improving corneal nerve fiber length in corneal neuropathy due to dry eye disease and diabetes. Low or very low certainty evidence was found for neuroregenerative therapies and dietary supplements not altering corneal immune cell density. This review identifies a need to standardize the clinical definition of corneal neuropathy and define a minimum set of core outcome measures. Together, this will provide a foundation for improved phenotyping of clinical populations in studies, and improve capacity to synthesize data to inform evidence-based based care. Protocol registration: PROSPERO ID: CRD42022348475.

Association between systemic medication use and severity of dry eye signs and symptoms in the DRy eye assessment and management (DREAM) study

PURPOSE

Some systemic medications are reported to be associated with dry eye disease (DED), yet their associations with the severity of DED signs and symptoms are not well studied. To evaluate these associations, we performed a secondary analysis of data from the DRy Eye Assessment and Management (DREAM) Study.

METHODS

Participants (N = 535) were assessed for DED signs using tear break-up time (TBUT), Schirmer testing, corneal fluorescein staining, conjunctival lissamine green staining, meibomian gland dysfunction (MGD), and tear osmolarity and DED symptoms using the Ocular Surface Disease Index (OSDI). We derived a composite signs severity score from the 6 DED signs and categorized participant-reported systemic medications into antidepressants, antihistamines, aspirin, corticosteroids, diuretics, nonsteroidal anti-inflammatory drugs, proton pump inhibitors, statins, vitamin D3, and medications for diabetes mellitus, hypertension, hypothyroidism, migraine, and seizure. Generalized linear models were used to compare DED symptom and sign scores between medication users and non-users, with adjustment for factors associated with DED severity.

RESULTS

Compared to non-users, antihistamine users had lower TBUT (p = 0.01) and higher OSDI score (p = 0.02); aspirin users had lower TBUT (p = 0.02); corticosteroid users had lower TBUT (p = 0.02), lower Schirmer test scores (p = 0.03), higher cornea fluorescein staining (p = 0.01), higher composite severity score (p = 0.01), and higher OSDI score (p = 0.03); seizure medication users had higher composite severity score (p = 0.02); vitamin D3 users had lower TBUT (p = 0.001) and greater MGD (p = 0.03); and diuretic users had less MGD (p = 0.03).

CONCLUSIONS

Certain systemic medications may be associated with more severe DED. This may guide prescription practices in patients with DED.

Ocular pain after refractive surgery: interim analysis of frequency and risk factors

PURPOSE

To examine the frequency and risk factors for ocular pain after laser assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

METHODS

Prospective study of individuals undergoing refractive surgery at two different centers. Participants rated their ocular pain on a 0 - 10 Numerical Rating Scale (NRS) pre-surgery and 1 day, 3 months, and 6 months post-surgery. A clinical examination focused on ocular surface health was performed 3- and 6-months post-surgery. Persistent ocular pain was defined as an NRS score ≥ 3 at both 3- and 6-months post-surgery (cases) and this group was compared to individuals with NRS scores <3 at both time points (controls).

RESULTS

109 individuals underwent refractive surgery (87% LASIK; 13% PRK) and were followed for 6 months after surgery. Mean age was 34±8 years (range 23 to 57); 62% self-identified as female, 81% as White, 33% as Hispanic. Eight (7%) individuals reported ocular pain (NRS ≥ 3) prior to surgery, with the frequency of ocular pain increasing after surgery to 23% (n=25) at 3 months and 24% (n=26) at 6 months. Twelve individuals (11%) reported an NRS ≥ 3 at both time points and comprised the persistent pain group. Factors that predicted persistent pain after surgery in a multivariable analysis were: (a) ocular pain pre-surgery (b) symptom report of depression prior to surgery (Patient Health Questionnaire-9: PHQ9: odds ratio (OR) 1.3, 95% confidence interval (CI) 1.1-1.6, p=0.01); (c) use of an oral anti-allergy medication pre-surgery (OR 13.6, 95% CI 2.1-89.3, p=0.007). (d) pain intensity day 1 after surgery (OR: 1.6, 95% CI 1.2-2.2, p=0.005); Ocular surface signs of tear dysfunction were not related to pain complaints. Most individuals (>90%) were completely or somewhat satisfied with their vision at 3 and 6 months.

CONCLUSIONS

Eleven percent of individuals reported persistent ocular pain after refractive surgery, with several pre- and peri-operative factors predicting pain after surgery.

Efficacy and safety of pregabalin in eye pain: A systematic review

BACKGROUND

The pregabalin is approved for the management of persistent pain. The aim of this study is to assess the advantages and disadvantages of the use of pregabalin in eye pain management.

METHODS

The PubMed, Cochrane Library, Embase, and Web of Science databases were searched until January 2022 for randomized controlled trials. Randomized, double-blinded trials comparing pregabalin with placebo in eye pain management were included. The primary outcome was visual analog scale or numerical rating scale at acute (24 hours) and chronic (≥7 days after surgery) timepoints. The secondary outcomes were analgesic medication requirements and pregabalin-related complications (nausea, vomiting, dizziness, and headache). We also compared the effect of pregabalin on dry-eye syndrome.

MAIN RESULTS

Six relevant articles were identified that studied the use of pregabalin as pain relief for photorefractive keratectomy (n = 2), laser epithelial keratomileusis (n = 1), laser-assisted in situ keratomileusis (n = 1), eyelid surgery (n = 1), and dacryocystorhinostomy (n = 1). Pregabalin was associated with a significant reduction in pain scores (95% confidence interval = -0.41 [-0.76--0.06]) 24 hours after surgical procedures. The data were insufficient to draw conclusions regarding dry eye symptoms. Because of the high heterogeneity of outcomes regarding adverse effects, there is no conclusion regarding the safety of pregabalin in eye pain.

CONCLUSIONS

Pregabalin reduced acute eye pain but had no significant effect on long-term analgesia after ophthalmological surgery in adults. It had no effect on dry-eye symptoms after ocular surgery. Further studies on the safety of pregabalin in eye pain management are required to draw solid conclusions.

Post-LASIK dry eye disease: A comprehensive review of management and current treatment options

Laser-assisted in situ keratomileusis (LASIK) is a unique corneal stromal laser ablation method that uses an excimer laser to reach beneath corneal dome-shaped tissues. In contrast, surface ablation methods, such as photorefractive keratectomy, include removing epithelium and cutting off the Bowman's layer and the stromal tissue of the anterior corneal surface. Dry eye disease (DED) is the most common complication after LASIK. DED is a typical multi-factor disorder of the tear function and ocular surface that occurs when the eyes fail to produce efficient or adequate volumes of tears to moisturize the eyes. DED influences quality of life and visual perception, as symptoms often interfere with daily activities such as reading, writing, or using video display monitors. Generally, DED brings about discomfort, symptoms of visual disturbance, focal or global tear film instability with possible harm to the ocular surface, the increased osmolarity of the tear film, and subacute inflammation of the ocular surface. Almost all patients develop a degree of dryness in the postoperative period. Detection of preoperative DED and committed examination and treatment in the preoperative period, and continuing treatments postoperatively lead to rapid healing, fewer complications, and improved visual outcomes. To improve patient comfort and surgical outcomes, early treatment is required. Therefore, in this study, we aim to comprehensively review studies on the management and current treatment options for post-LASIK DED.

Opioids and Ocular Surface Pathology; A Literature Review of New Treatments Horizons

This review discusses the role of opioids in the corneal surface and the different pathways and therapeutic methods of management. A literature review was performed using PubMed database. For the database search, the main searching words “opioid” and “topical opioid treatment” were used with the descriptors “cornea”, “ocular surface”, “neuropathic corneal pain”, “corneal sensitivity” and “naltrexone”; original scientific articles and reviews were included to achieve the purpose of the review. The endogenous opioid system has relevant functions in the organism, and in daily use, opioids are used as painkillers. However, these drugs may be employed for other indications as opioid pathways have a wide spectrum. The corneal surface for topical treatment is easily accessible, hence sparing the side effects of systemic opioids. Instillation of opioid antagonist substances, such as naltrexone, increases corneal healing rates and stimulates the division of corneal epithelium cells without deleterious effects. The natural modulation of endogenous opioids controls different forms of pain, including inflammatory and neuropathic pain, both in the ocular surface and in the central nervous system. There are diverse methods in controlling pain using opioids, especially in refractory forms. This review attempts to collect the literature about corneal surface and opioid pathways to provide an overview image and a possible direction of the news treatments.

Effects of Lipiflow Treatment Prior to Cataract Surgery: A Prospective, Randomized, Controlled Study

To investigate the effects of preoperative Lipiflow (Johnson & Johnson, Jacksonville, FL, USA) treatment before cataract surgery on meibomian gland dysfunction (MGD) and dry eye induced by surgery.

DESIGN

Prospective, randomized controlled study.

METHODS

This study comprised 124 eyes of 124 patients with planned surgery for senile cataract. Participants were randomly allocated into control and Lipiflow groups based on administration of Lipiflow treatment 3 weeks before cataract surgery. For meibomian gland (MG) evaluation, MG atrophy, degree of gland expressibility, and quality of gland secretions were examined at the baseline visit and 1 and 3 months postoperatively. Ocular surface parameters of tear film break-up time, Oxford corneal staining score, and tear film lipid layer thickness were measured at each visit. Ocular Surface Disease Index and Dry Eye Questionnaire were also assessed.

RESULTS

The control group exhibited a significant decrease in MG expressibility, worsened meibum quality, decreased lipid layer thickness, and worsened corneal staining after cataract surgery. Also, dry eye symptom showed significant worsening. Conversely, the Lipiflow group showed significantly improved MG patency and meibum quality, increased tear film break-up time, and reduced corneal staining, and presented improved subjective outcomes reported on both Ocular Surface Disease Index and Dry Eye Questionnaire. The improvement of each parameter in the Lipiflow group showed a linear correlation with baseline MGD grade. In addition, patients without baseline MGD showed less worsening or improvement of MGD and dry eye induced by surgery, with preoperative Lipiflow treatment.

CONCLUSIONS

Preoperative Lipiflow treatment conducted before cataract surgery may be a safe and effective intervention for relieving MGD and dry eye induced by surgery. It might be recommended not only for the patients with preoperative MGD but also for those without baseline MGD, to prevent the development of MGD and dry eye induced by ocular surgeries.

Topical TRPM8 Agonist for Relieving Neuropathic Ocular Pain in Patients with Dry Eye: A Pilot Study

Background: Activation of TRPM8, a cold-sensing receptor located on the cornea and eyelid, has the potential to relieve the neuropathic ocular pain (NOP) in dry eye (DE) by inhibiting other aberrant nociceptive inputs. We aimed to investigate the effect of a topical TRPM8 agonist, cryosim-3 (C3), on relieving DE-associated NOP. Methods: We conducted a prospective pilot study of 15 patients with DE-associated NOP. These patients applied topical C3 to their eyelid, 4 times/day for 1 month. The patients underwent clinical examinations. They also completed the Ocular Pain Assessment Survey (OPAS), which is a validated questionnaire for NOP, at baseline, 1 week, and 1 month after treatment. Result: At 1 week, the OPAS scores of eye pain intensity, quality of life (driving/watching TV, general activity, sleep, and enjoying life/relations with other people), and associated factors (burning sensation, light sensitivity, and tearing) improved. The total OPAS scores of eye pain intensity, quality of life, and associated factors remained improved at 1 month. The Schirmer test scores also improved at 1 month. Conclusion: TRPM8 agonist (C3) could be a novel agent for treating patients with DE-associated NOP who are unresponsive to conventional treatments.

Pain sensitivity and autonomic nervous system parameters as predictors of dry eye symptoms after LASIK

PURPOSE

Differences in pain processing and autonomic function among patients have been implicated in the development of chronic pain after surgery. This study was designed to evaluate whether pain and autonomic metrics predict severity of chronic dry eye (DE) symptoms after LASIK, as there is increasing evidence that DE symptoms may be manifestations of persistent post-operative ocular pain.

METHODS

Secondary analysis of prospective randomized clinical trial. Patients were treated with either pregabalin or placebo. As no significant differences in DE symptoms were detected by treatment allocation at six months, all participants were grouped together for the present analyses. Subjects were evaluated pre-LASIK with regard to evoked pain sensitivity (utilizing quantitative sensory testing), autonomic metrics and DE and ocular pain symptoms (via validated questionnaires). Measures of DE and ocular pain were assessed post-LASIK, and the Dry Eye Questionnaire 5 (DEQ5) score 6-months after surgery was the primary outcome of interest.

RESULTS

43 individuals were randomized to pregabalin (n = 21) or placebo (n = 22). 42 completed the 6-month visit. Several baseline autonomic metrics correlated with 6-month post-operative DEQ5 scores, including lower systolic (r -0.37, p = 0.02) and diastolic blood pressure (r -0.32, p = 0.04). Ocular pain at 6 months was also negatively correlated with blood pressure (r -0.31, p = 0.047). The presence of painful aftersensations was a significant predictor of chronic DE symptoms at 6 months (mean DEQ5 scores: 8.0 ± 1.9 versus 5.0 ± 5.0, p = 0.009).

CONCLUSIONS

Heightened parasympathetic tone and prolonged pain sensitivity measured prior to surgery predicted greater DE symptom severity 6 months after LASIK.

TRIAL REGISTRATION

NCT02701764.

Effects of taking pregabalin (Lyrica) on the severity of dry eye, corneal sensitivity and pain after laser epithelial keratomileusis surgery

BACKGROUND

Corneal nerve damage after laser epithelial keratomileusis (LASEK) is thought to be the cause of dry eye and pain. Therefore, we investigated whether taking pregabalin (Lyrica), which reduces peripheral neuropathic pain, alleviates corneal nerve sensitivity after surgery and reduces dry eye and pain.

METHODS

Patients were treated with pregabalin (150 mg two times a day for 15 days) from the day before surgery onward and compared with those who did not receive the medications. Before surgery, the severity of dry eye was assessed. Then, corneal sensitivity was assessed by esthesiometry and pain was assessed according to the Visual Analogue Scale. Images of the sub-basal nerve plexus were analysed using confocal microscopy to evaluate nerve regeneration at 6 months.

RESULTS

Forty eyes in the pregabalin group and 40 eyes in the control group were included in this study. No significant differences regarding the severity of dry eye, corneal sensitivity test results and nerve fibre density existed between the two groups until 6 months. The pregabalin group showed significantly reduced pain at 1 week.

CONCLUSIONS

Taking pregabalin during LASEK surgery may affect corneal nerve sensitivity and reduce pain. However, for up to 6 months thereafter, corneal sensitivity and nerve fibre density are not significantly different from findings in the control group, so pregabalin does not seem to affect nerve regeneration or structural changes.

Treatment Response to Gabapentin in Neuropathic Ocular Pain Associated with Dry Eye

PURPOSE

To investigate the response to gabapentin treatment in patients with dry eye (DE) accompanied by features of neuropathic ocular pain (NOP), and to analyze the differences between clinical manifestations of the groups according to treatment response.

METHODS

We retrospectively reviewed the records of 35 patients with DE accompanied by NOP features and obtained information on their medical history and previous ocular history. The patients underwent clinical examinations of the tear film, ocular surface, and meibomian gland and completed the Ocular Pain Assessment Survey (OPAS). One month after treatment with topical eye drops, add-on of gabapentin treatment was determined according to the Wong-Baker FACES Pain Rating Scale (WBFPS). A reduction of 2 points or more on the WBFPS was considered a positive treatment response. Enrolled patients were divided into three groups according to the treatment response: topical treatment response group (group 1, n = 11); gabapentin response group (group 2, n = 13); and gabapentin non-response group (group 3, n = 11). The medical history, clinical parameters, and OPAS scores were compared between groups.

RESULTS

The incidence of systemic comorbidities was higher in group 2 than in other groups. The corneal staining scores were lower in groups 2 and 3 than in group 1. Among the treatment response groups, group 2 showed improvements in OPAS scores of ocular pain severity, pain other than eyes, and quality of life, while group 1 showed improved OPAS scores of ocular pain severity and ocular associated factors. Group 2 exhibited lower scores of pains aggravated by mechanical and chemical stimuli than group 3.

CONCLUSIONS

Gabapentin could be effective in patients who have systemic comorbidity and less pain evoked by mechanical and chemical stimuli for the treatment of DE patients with NOP, which is refractory to topical treatment.

Eye pain in the white and quiet eye

PURPOSE OF REVIEW

Eye pain is one of the most common presenting symptoms in ophthalmology. It can range from bothersome to debilitating for patients, and it can be vexing for clinicians, especially in the white and quiet eye. The purpose of this review is to provide updates of recent literature regarding eye pain and to communicate our current understanding regarding the evaluation and management of conditions that cause eye pain with a relatively normal examination.

RECENT FINDINGS

This review concerns recent literature regarding eye pain in the white and quiet eye. It is arranged by cause of pain and discusses dry eye syndrome, recurrent corneal erosion, postrefractive surgical pain, eye strain, intermittent angle closure, benign essential blepharospasm, trochleodynia, trochleitis and trochlear headache, and posterior scleritis.

SUMMARY

Eye pain in the white and quiet eye remains a difficult-to-navigate topic for practitioners. However, a careful history and focused physical examination can elucidate the diagnosis in many cases. Recent updates to the literature have advanced our knowledge of how to identify and treat the underlying causes of eye pain.

Autoimmune Dry Eye without Significant Ocular Surface Co-Morbidities and Mental Health

Dry eye symptoms can negatively affect the psychological, physical, and social functioning, which can potentially impair the health-related quality of life. This review evaluated the association between autoimmune related dry eye in the absence of significant ocular surface co-morbidities and mental health. This review found a significantly higher prevalence of mental health disorders (such as depression and anxiety) in systemic lupus erythematous, rheumatoid arthritis, systemic sclerosis, Behcet’s disease, and primary Sjogren’s syndrome patients when compared to the general population. Moreover, patients with depression and anxiety interpret ocular sensations differently than healthy controls and the perception of dry eye symptoms can be influenced by their mood. Somatization is common in depression, and this could influence the perception of ocular discomfort. Anti-depressants and anxiolytics with their potential side effects on the tear film status may also contribute or aggravate the dry eye symptoms in these patients. Although ophthalmologists manage the dry eye disease, as per standardized algorithms, they should be mindful of different ocular sensation interpretation and coexistent mental health issues in a large number of this patient group and initiate a multidisciplinary management plan in certain cases. While rheumatologists look after their autoimmune condition, it may be worth liaising with GP and/or psychiatrist colleagues in order to address their neuropathic type pain and mental health co-morbidities.

Comparison of clinical characteristics of post-refractive surgery-related and post-herpetic neuropathic corneal pain

Purpose:

To compare the clinical characteristics and in vivo confocal microscopy (IVCM) findings of patients with neuropathic corneal pain (NCP) due to refractive surgery (RS-NCP) and herpetic eye disease (H-NCP) to controls.

Methods:

Sixteen patients with RS-NCP and 7 patients with H-NCP, and 37 healthy reference age- and sex-matched healthy controls were included to the study. The medical records were reviewed for demographic features, detailed disease history, ocular surface disease index (OSDI), ocular pain assessment survey (OPAS) scores. IVCM images of patients were analyzed and compared to reference controls by two masked observers.

Results:

The mean pain intensity score for the last 24 h (5.1 ± 2.4 vs. 3.9 ± 1.2; p = 0.27), last 2 weeks (6.1 ± 2.5 vs. 4.8 ± 2.3; p = 0.13) for RS-NCP vs. H-NCP respectively, and quality of life scores (p = 0.23) were similar in both groups. Quality of life, especially mood (p = 0.06) and enjoying life/relations to others (p = 0.10) were affected in both groups, but were not statistically significant between groups. The mean total nerve density was lower in RS-NCP (5,702.4 ± 4,599.0 μm/mm²) compared to their respective controls (26,422.8 ± 4,491.0; p < 0.001) and in the H-NCP group (2,149.5 ± 2,985.9) compared to their respective controls (22,948.8 ± 3,169.0; p < 0.001). Alterations in DC density were similar between all groups (38.3 ± 48.0 cells/mm² in RS-NCP, 61.0 ± 76.9 in H-NCP, p = 0.95).

Conclusion:

Neuropathic corneal pain patients due to refractive surgery show similar clinical characteristics, pain levels, quality of life impact, and IVCM findings as patients with NCP due to herpetic eye disease.