Efficacy and safety of topical diclofenac in reducing ocular pain after excimer photorefractive keratectomy

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.

Use of topical bromfenac for treating ocular pain and inflammation beyond cataract surgery: a review of published studies

Topical ophthalmic nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to treat postoperative inflammation and pain following cataract surgery and for treatment and prophylaxis of pseudophakic cystoid macular edema (CME). Bromfenac is a brominated NSAID with strong in vitro anti-inflammatory potency. Like other ophthalmic NSAIDs, bromfenac is often used outside of the cataract surgery setting. This paper provides an overview of bromfenac’s preclinical ocular pharmacology and pharmacokinetics, followed by a review of 23 published clinical studies in which various marketed bromfenac formulations were used for conditions other than cataract surgery or pseudophakic CME. These include: post-refractive eye surgery; macular edema associated with diabetes, uveitis, or retinal vein occlusion; inflammation associated with age-related macular degeneration; pain related to intravitreal injections; and other ocular anterior segment and surface disorders with an inflammatory component. The published evidence reviewed supports the safety and effectiveness of bromfenac in these additional ophthalmic indications. Bromfenac was well tolerated when given alone or in combination with intravitreal anti-vascular endothelial growth factor agents, topical corticosteroids, or topical mast-cell stabilizers. The most common adverse event reported was ocular irritation. No serious adverse events (ie, corneal epithelial disorders) were reported, although the majority of studies did not systematically evaluate potential side effects. Corneal complications, such as melts reported with diclofenac and ketorolac, were not observed with bromfenac in the studies. In summary, published study data support the clinical utility of bromfenac in various ocular disorders beyond post-cataract surgery. Additional studies are warranted to further define the potential role of bromfenac ophthalmic solution in clinical practice.

Comparison of analgesic effect of preoperative topical Diclofenac versus Ketorolac on postoperative pain after Corneal Collagen Cross Linkage

OBJECTIVE

To compare post-operative pain relieving effect of topical diclofenac 0.1% versus ketorolac 0.5% in Corneal Collagen Cross Linking (CXL) for patients diagnosed with keratoconus.

METHODS

This randomized controlled trial was carried out for six months from October 2016 to March 2017. We included young patients having keratoconus with k-readings greater than 47D and central corneal thickness more than 400 microns. All the patients received single dose one drop of topical diclofenac 0.1% to (Group-A) and ketorolac 0.5% to (Group-B) 30 minutes in advance of the corneal collagen cross linking (CXL) procedure. The CXL was performed with topical 0.1% riboflavin eye drops in 20% dextran as a photo sensitizer. After 36 hours of the CXL procedure, the postoperative intensity of pain was assessed verbally by patients with the help of visual analog scale (VAS) numbers from zero to five where 0 designated no pain & 5 symbolized worst pain.

RESULTS

The study comprised sixty eyes of forty one patients. Out of total 16 were male while 25 female patients. The mean age of the patients was 24.27 ± 2.93 years (range 20 to 29 years). In the conclusive analysis, diclofenac 0.1% was used on 30 patients in Group-A and ketorolac 0.5% on 30 subjects in Group-B. Pain relieving scores in Group-A (diclofenac 0.1%) was 2.57 ± 0.67 while in Group-B (ketorolac 0.4% treated arm) was 3.20 ± 0.61.

CONCLUSION

Topical diclofenac 0.1% is statistically comparable to topical ketorolac 0.5% in precluding severity of pain after corneal collagen cross linkage operation.

Efficacy and perioperative timing of bromfenac in the management of ocular discomfort after femtosecond laser-assisted laser in situ keratomileusis

PURPOSE

To evaluate the safety, efficacy, and appropriate perioperative timing of the use of topical bromfenac ophthalmic solution 0.07% after femtosecond laser-assisted laser in situ keratomileusis (LASIK).

SETTING

Keil LASIK Vision Center, Grand Rapids, Michigan, USA.

DESIGN

Prospective case series.

METHODS

Ocular discomfort was assessed 1, 2, and 5 hours postoperatively and the following morning using the Ocular Comfort Grading Assessment in patients treated with topical bromfenac 0.07% or artificial tears just before, just after, or before and after femtosecond laser-assisted LASIK. Visual outcomes and complications were noted up to 24 hours.

RESULTS

The study enrolled 64 patients (120 eyes). Patients who were treated with bromfenac 0.07% just before or before and after femtosecond laser-assisted LASIK showed the greatest statistically significant decrease in several discomfort scores within the first few hours in comparison with the control group. Two hours after surgery, the majority of patients who were treated before and after LASIK were sleeping comfortably. There were no significant differences in visual acuity; 1 day postoperatively, the uncorrected distance visual acuity was 20/20 in 106 eyes (89%) and 20/25 or better in 116 eyes (97%). At 3 months, all patients had binocular distance visual acuity of 20/20 or better and 86% of patients had 20/15 or better.

CONCLUSION

Ocular discomfort after femtosecond laser-assisted LASIK was reduced with a single dose of topical bromfenac 0.07% given immediately before surgery or given just before and after surgery and was typically minimal in all groups the morning after surgery.

Efficacy of systemic diclofenac sodium on intravitreal concentration

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs), as an alternative, are replacing corticosteroids in ocular inflammatory diseases. Diclofenac has been used mainly topically, and recent focus has been on intravitreal delivery. Both of these methods have been shown to have complications in long-term application.

PURPOSE

To assess the efficacy of slow release oral diclofenac sodium on intravitreal concentration in experimental model of chemically injured eyes.

METHODS

In an experimental double-masked clinical trial, right eyes of 24 albino rabbits were chemically injured by 1 N NaOH. One hour after chemical injury, 10 cc suspension gavage containing 100 mg slow release diclofenac sodium was administered in all cases. 2, 4, 6, 12, 24, 48 h after gavage, vitreous samples were obtained in all cases. Intravitreal concentration of diclofenac sodium was evaluated in all samples using high-performance liquid chromatography (HPLC) method.

RESULTS

Intravitreal diclofenac levels by oral intake were enhanced by the inflammation in all the measurements. In inflamed eyes, diclofenac concentration was ten times more than control eye (2.658 ± 0.344 vs. 0.242 ± 0.0279 and 1.617 ± 0.527 vs. 0.148 ± 0.095; in 2 and 4 h, respectively). After 6 h, diclofenac concentration was statistically different, although it reduced below 1 μg/ml.

CONCLUSION

Diclofenac is delivered to the inflamed eye more than healthy eye. It seems that by oral diclofenac consumption, it is possible to make a significant intravitreal concentration.

Efficacy and safety of pain relief medications after photorefractive keratectomy: review of prospective randomized trials

The objective of this review was to provide a comprehensive overview and comparison of results from all prospective randomized trials published to date of medications used to treat pain after photorefrative keratectomy (PRK). A PubMed database search revealed 23 prospective and randomized studies. They included the following classes of medications: nonsteroidal antiimflammatory drugs (NSAIDs), anesthetics, opiates, acetaminophen, gabapentin, and pregabalin. The studies found that although the efficacy of drugs tended to be similar, tetracaine 1% and nepafenac 0.1% tended to have the most analgesic effect. Delayed corneal reepithelialization was a common side effect of both topical anesthetics and topical NSAIDs. Tetracaine 1% resulted in the most significant delay in reepithelialization when tested against placebo control compared with other topical medications tested against placebo. Concomitant use of topical NSAIDs and topical anesthetics, especially tetracaine, may have to be avoided to minimize the risk for delayed corneal healing.

FINANCIAL DISCLOSURE

Neither author has a financial or proprietary interest in any material or method mentioned.

Comparing the Efficacy of Ophthalmic NSAIDs in Common Indications

Objective: To review the commercially available ophthalmic nonsteroidal anti-inflammatory drugs (NSAIDs), identify opportunities for therapeutic substitutions within and outside of their Food and Drug Administration (FDA)-approved indications, and identify clinically superior drugs within the class for specific indications. Data Source: A PubMed search (1992 through January 2014) was performed on the terms diclofenac, ketorolac, flurbiprofen, bromfenac, and nepafenac. Study Selection and Data Extraction: Clinical trials, meta-analyses, and review articles were evaluated if they were written in English and pertained to human subjects. Studies were excluded if they were in vitro studies, solely evaluated pharmacokinetic or pharmacodynamic properties, did not relate to the topical ophthalmic route, did not evaluate the FDA-approved indications of any available ophthalmic NSAID, or compared a reviewed drug with a nonreviewed drug (without placebo comparison). Data Synthesis: A total of 67 articles met the criteria for evaluation. Article quality, study design, and dosing of the medications were assessed to determine the clinical applicability of the results. The quality of the article was determined using the Oxford Centre for Evidence-based Medicine Levels of Evidence 1. Conclusions: Many formulations of the 5 reviewed NSAIDs have been studied across the 4 primary indications. These indications are (1) pain and inflammation associated with cataract surgery, (2) pain associated with corneal refractive surgery, (3) inhibition of intraoperative miosis, and (4) seasonal allergic conjunctivitis. Several studies have directly compared drugs within this class and have identified instances in which certain selections are therapeutically superior or equivalent to another. This information provides practitioners with guidance in selecting an optimal medication.

Systemic absorption and adverse ocular and systemic effects after topical ophthalmic administration of 0.1% diclofenac to healthy cats

OBJECTIVE

To quantify plasma concentrations and determine adverse ocular, renal, or hepatic effects associated with repeated topical ophthalmic application of 0.1% diclofenac to healthy cats.

ANIMALS

8 healthy sexually intact male cats.

PROCEDURES

A randomized, placebo-controlled crossover study was conducted. A topical formulation of 0.1% diclofenac was administered 4 times/d for 7 days to 4 cats, and artificial tear (control) solution was administered to the other 4 cats. After a 12-day washout period, cats received the other treatment. Ophthalmic examinations were performed daily. Plasma samples were obtained on days 1 and 7 for pharmacokinetic analysis. A CBC, serum biochemical analysis, urinalysis, determination of urine protein-to-creatinine ratio, and determination of glomerular filtration rate were performed before the start of the study and after each 7-day treatment period.

RESULTS

Mild conjunctival hyperemia was the only adverse ocular effect detected. Maximal drug concentration and area under the curve were significantly higher on day 7 than on day 1. Diclofenac-treated cats had a significantly lower glomerular filtration rate than did control-treated cats after the second but not after the first treatment period, presumably associated with iatrogenic hypovolemia.

CONCLUSIONS AND CLINICAL RELEVANCE

Topical ophthalmic administration of 0.1% diclofenac was well tolerated in healthy cats, with only mild signs of ocular irritation. Detectable systemic concentrations of diclofenac were achieved with accumulation over 7 days. Systemic absorption of diclofenac may be associated with reduced glomerular filtration rate, particularly in volume-contracted animals. Topical ophthalmic 0.1% diclofenac should be used with caution in volume-contracted or systemically ill cats.

Pain and Its Determinants in Photorefractive Keratectomy

PURPOSE

To assess the determinants of early postoperative pain in photorefractive keratectomy.

DESIGN

A prospective cross-sectional study.

METHODS

One hundred and four myopic-astigmatic patients undergoing bilateral standard photorefractive keratectomy were evaluated for early postoperative pain severity. On day 1 postoperatively, the level of pain experienced was reported by the patient on a visual analog scale of 0 to 10. At the preoperative interview, data were collected on clinical, demographic, and social characteristics to find potential pain determinants.

RESULTS

The median reported pain level was 3. About 20% of subjects reported a pain score of 6 or higher, and 2.9% (6 eyes of 4 patients) reported the highest pain score. The presence of external eye inflammatory signs was associated with higher levels of pain (P < 0.001). Patients with a higher body mass index reported more severe pain (P = 0.006). An inverse association was found between pain and harmful lifestyle choices (P = 0.008). Demographic characteristics, history of contact lens wear, history of major operation, past experience of severe pain, knowledge about the operation's adverse effects, preoperative insomnia, preoperative anxiety, operative factors, and refractive indices were not related to the severity of pain experienced (all P > 0.05).

CONCLUSIONS

The association of pain with ocular surface inflammation suggests that inflammatory processes have a role in early postoperative pain, supporting the use of anti-inflammatory agents for pain management. Prescription of weight-adjusted dosages of analgesics is recommended on the basis of the association between severity of postoperative pain and body mass index.

Shortening ocular pain duration following intravitreal injections

PURPOSE

To determine ocular pain duration after routine in-office intravitreal injection and to determine whether topical eyedrops are beneficial in increasing patient comfort.

METHODS

Forty injection-naïve patients receiving routine intravitreal injections of bevacizumab for age-related macular degeneration were randomized into 3 groups: group 1 (control, no drops), group 2 (generic artificial tears), and group 3 (ketorolac tromethamine 0.4% eyedrops). Those who received topical medications were given a Visual Analog Pain score survey and asked to record their pain on a scale from 0 (no distress) to 10 (unbearable distress) daily until a score of 0 was achieved, at which point they were instructed to discontinue use of their given drops. Self-reported pain scores were assessed.

RESULTS

Pain after routine intravitreal injection lasts on average between 3 and 7 days. Patients receiving topical ketorolac eyedrops reported the fewest average number of pain days (2.25±1.22) vs patients receiving artificial tears (3.54±1.13) or those who received no postprocedure eyedrops (5.13±1.25); p&lt;0.05. At most, patients receiving ketorolac eyedrops reported 3 days of recordable pain. Those who received artificial tears reported at most 5 days of recordable pain, and patients who did not receive any postprocedure eyedrops reported at most 7 days of recordable pain.

CONCLUSIONS

Pain after intravitreal injection is generally mild, may be reduced by postinjection topical ketorolac eyedrops, and lasts less than 1 week.

Effect of preemptive topical diclofenac on postoperative pain relief after photorefractive keratectomy

PURPOSE

To assess the prophylactic effect of preoperative application of topical diclofenac on postoperative pain control in patients having photorefractive keratectomy (PRK).

SETTING

Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.

DESIGN

Randomized masked clinical trial.

METHODS

In this paired-eye study, patients having bilateral PRK received 1 drop of diclofenac 0.1% in 1 eye and 1 drop of placebo in the fellow eye 2 hours before PRK. Postoperatively, both arms of the trial (both eyes of each patient) received topical diclofenac every 6 hours for 2 days. One day and 2 days postoperatively, patients were asked to rate the perceived pain in each eye using an 11-point verbal numerical rating scale. A trained examiner noted the eye-specific responses.

RESULTS

All 70 patients (140 eyes) completed the study and were included in the statistical analysis. Twenty-four hours after PRK, patients reported pain scores that were clinically and statistically significantly lower in the eyes pretreated with diclofenac than in the fellow eyes (0.97 versus 2.09) (P=.018). Pain scores at 2 days did not differ significantly (P=.877).

CONCLUSION

Administration of a single drop of topical diclofenac 0.1% 2 hours before PRK seemed to increase the efficacy of postoperative pain management in a clinically and statistically significant manner.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Comparison of the analgesic efficacy and safety of nepafenac ophthalmic suspension compared with diclofenac ophthalmic solution for ocular pain and photophobia after excimer laser surgery: a phase II, randomized, double-masked trial

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of nepafenac ophthalmic suspension 0.03% and 0.1% for the treatment of postoperative pain and photophobia in patients undergoing excimer photoreactive keratectomy (PRK).

METHODS

In this 7-day, randomized, double-masked, parallel-group trial at 2 sites, patients undergoing PRK surgery were randomly assigned to receive nepafenac ophthalmic suspension 0.03% or 0.1%, or diclofenac sodium ophthalmic solution 0.1%. Patients were treated on day 0 (surgery) and day 1 (the day after surgery). The dose regimen for all 3 treatments was the same. On day 0, patients received 2 drops in the operative eye -1 hour before surgery; 2 drops within 1 hour after surgery; 1 drop -4 hours after the first postoperative dose; and 1 drop -8 hours after the first postoperative dose. On day 1, patients instilled 1 drop of study drug QID. Thereafter, the study medication was discontinued. In the perioperative period, study personnel instilled the drops. The patients instilled the drops when they went home. Patients recorded pain and photophobia from day 0 through day 2, rating pain from 0 to 9 on a visual analog scale (0=none, 9=extreme) and photophobia from 0 to 3 on an ordinal, categoric scale (0=none, 3=severe). Patients were permitted to take acetaminophen 500 mg as needed for pain. They returned for postoperative follow-up visits on days 1, 3, and 7. Adverse events were documented when reported by the patients themselves, and when study personnel asked about specific events.

RESULTS

Sixty patients (20 per group) were enrolled. On the day of surgery, there were no significant differences between groups, except at 3 hours after surgery, when the nepafenac 0.03% group had a significantly higher mean pain score than the nepafenac 0.1% group (4.0 vs 3.0; P<0.038). On day 2, the nepafenac 0.1% group had less pain at bedtime than the diclofenac group (mean score, 1.9 vs 3.1; P<0.024) and less photophobia in the morning (mean score, 1.2 vs 1.8; P<0.023). For the nepafenac 0.03% group, the mean pain and mean photophobia scores were 2.5 and 1.6, respectively. There were no significant differences between the 3 treatment groups in the proportion of patients who took acetaminophen for pain at any time point (P=NS). There was no statistically significant difference in corneal re-epithelialization rates among the 3 groups. Adverse events were infrequent, and no serious adverse events occurred. Two ocular adverse events related to therapy occurred: a corneal infiltrate in 1 patient in the nepafenac 0.03% group; and ocular discomfort in 1 patient in the nepafenac 0.1% group. Both patients continued the study.

CONCLUSIONS

Both nepafenac 0.03% and 0.1% were effective for treatment of pain and photophobia in these patients undergoing PRK surgery. There was no difference in the proportion of patients who took rescue acetaminophen for pain. All treatments were well tolerated in these patients.

A comparative study of post-operative pain in laser epithelial keratomileusis versus photorefractive keratectomy

BACKGROUND

To compare the level of post-operative pain associated with two methods of excimer laser corneal refractive surgery: PRK (photorefractive keratectomy) versus LASEK (laser epithelial keratomileusis).

METHODS

14 patients undergoing simultaneous bilateral myopic PRK were included in the study. The first eye of each patient was randomly allocated for treatment by either LASEK or PRK with alcohol-assisted epithelial debridement and second eyes were treated with the other technique. Laser corneal ablation was performed with Nidek EC-5000 excimer laser by one surgeon (MAA) using the same algorithm. Post-operatively, all patients had declofenac sodium 0.1% eye drops four times a day, lorazepam 2mg at night and two solpadol (paracetamol 500mg and codeine phosphate 30mg) tablets every six hours orally for two days. Chloramphenicol 0.5% drops four times a day were also administered for seven days. The level of pain in each eye was assessed 2, 12, 24 and 48 hours following laser surgery using a descriptive pain score from 0 to 10. Statistical analysis was performed using paired t test.

RESULTS

The mean pain score at two hours post-operatively was 3.5 +/- 2.24(SD) in the LASEK group and 5.7 +/- 2.02(SD) in the PRK group. This difference is statistically significant. At 12 hours it was 4.33 +/- 2.53 (SD) and 4.75 +/- 2.30 (SD), at 24 hours it was 3.71 +/-2.84 (SD) and 4.00 +/- 2.48 (SD), and at 48 hours it was 2.86 +/- 3.43 (SD) and 2.21 +/- 2.55 (SD). There was no statistically significant difference in the pain score at these intervals.

CONCLUSIONS

Post-operative pain was less in eyes treated with LASEK than eyes treated with PRK 2 hours following laser surgery. This was statisticaly significant and there was no statistically significant difference at 12, 24 and 48 hours.

Histopathology of corneal melting associated with diclofenac use after refractive surgery

PURPOSE

To describe the histopathology of the cornea in 3 cases of corneal melting associated with diclofenac therapy after refractive surgery procedures.

SETTING

Clinic and pathology laboratory.

METHODS

Three cases of corneal melting associated with diclofenac therapy (2 after laser in situ keratomileusis [LASIK] and 1 after mini-radial keratectomy enhancement of a LASIK undercorrection) were studied using patient and referring physician interviews, chart reviews, and histopathologic examination of the corneal tissue.

RESULTS

In all 3 cases, the flaps were dislocated and the stromal corneal bed was exposed. Diclofenac, generic or brand name, was used in all cases; in 1 case, both generic and brand name were used. Dosing and duration varied, but in all 3 cases diclofenac was used at least 4 times a day for at least 3 days after LASIK. Topical steroids were also prescribed, but 1 patient did not use them. Preoperative medical conditions were present in 2 cases. Histologic analysis showed evidence of an inflammatory response in advanced cases and keratolysis and lack of inflammatory cells in the flaps that were amputated early.

CONCLUSIONS

The use of generic or brand-name diclofenac with or without adjunctive topical steroids after LASIK can be associated with corneal melting when the LASIK flap is dislodged and the corneal stromal bed exposed. Caution is recommended with diclofenac use after LASIK in such cases.

Role of the bandage soft contact lens in the postoperative laser in situ keratomileusis patient

PURPOSE

To determine whether a bandage soft contact lens (BSCL) is routinely needed in the postoperative laser in situ keratomileusis (LASIK) patient and whether topical tetracaine 0.5% or diclofenac sodium 0.1% (Voltaren) is more effective in relieving patient discomfort than a BSCL.

SETTING

LCA-Vision Center, Toronto, Ontario, Canada.

METHODS

In this prospective randomized comparative study, all patients had bilateral simultaneous LASIK procedures. Post-LASIK patient comfort was evaluated through 3 arms of the study: BSCL versus no BSCL, 40 consecutive patients with 1 eye randomized to receive a BSCL and no BSCL in the fellow eye; BSCL versus tetracaine 0.5%, 26 consecutive patients with 1 eye randomized to receive a BSCL and tetracaine 0.5% in the fellow eye; tetracaine 0.5% versus Voltaren, 54 consecutive patients with 1 eye randomized to receive tetracaine 0.5% and Voltaren in the fellow eye.

RESULTS

The patient preferences after LASIK were as follows: BSCL versus no BSCL-12 (30%) versus 23 (58%) (P =.062); BSCL versus tetracaine 0.5%-4 (15%) versus 22 (85%) (P <.001). On average, the eyes with no BSCL had a 2-line improvement in uncorrected visual acuity over the BSCL eyes. Tetracaine 0.5% versus Voltaren-13 (24%) versus 21 (39%) (P =.170).

CONCLUSIONS

The routine use of a BSCL in the postoperative LASIK patient is not necessary. Voltaren and tetracaine 0.5% were safe and more effective in relieving postoperative patient discomfort and resulted in improved visual acuity immediately postoperatively.

LASIK complications: etiology, management, and prevention

Laser in situ keratomileusis (LASIK) is a rapidly evolving ophthalmic surgical procedure. Several anatomic and refractive complications have been identified. Anatomic complications include corneal flap abnormalities, epithelial ingrowth, and corneal ectasia. Refractive complications include unexpected refractive outcomes, irregular astigmatism, decentration, visual aberrations, and loss of vision. Infectious keratitis, dry eyes, and diffuse lamellar keratitis may also occur following LASIK. By examining the etiology, management, and prevention of these complications, the refractive surgeon may be able to improve visual outcomes and prevent vision-threatening problems. Reporting outcomes and mishaps of LASIK surgery will help refine our approach to the management of emerging complications.

Saxitoxin: an anesthetic of the deepithelialized rabbit cornea

PURPOSE

The aim of the current study was to define the efficacy of saxitoxin as a corneal anesthetic in rabbits after mechanical corneal abrasion and photorefractive keratectomy (PRK).

METHODS

Twelve Dutch belted rabbits were given a single 1.2-microg dose of saxitoxin or vehicle after mechanical abrasion of the cornea. Corneal sensation was evaluated hourly for 6 hours. A second group of 12 Dutch belted rabbits was given a 1.2-microg dose of saxitoxin or vehicle every 5 hours for 30 hours after PRK. Corneal sensation was evaluated after 5, 10, 15, 20, 25, and 30 hours. Pachometry was performed before PRK and again after the epithelial defects had healed. The rate of epithelial defect closure was assessed by measuring the epithelial defect size 25, 42, 65, 88, and 113 hours after PRK.

RESULTS

A dose of 1.2 microg of saxitoxin given every 5 hours produced continuous corneal anesthesia after PRK. There was no difference in the rate of wound healing between eyes treated with saxitoxin and vehicle. There was no difference in the degree of wound healing, as measured by pachometry, between eyes treated with saxitoxin and vehicle. There were no apparent ocular or systemic toxic effects from saxitoxin administration.

CONCLUSION

At a dose of 1.2 microg, saxitoxin is a safe, effective, long-acting corneal anesthetic in rabbits after PRK.

Comparison of laser epithelial keratomileusis and photorefractive keratectomy for low to moderate myopia

PURPOSE

To compare the effectiveness, safety, and stability of laser epithelial keratomileusis (LASEK), a modified photorefractive keratectomy (PRK) technique, with those of conventional PRK for low to moderate myopia.

SETTING

Department of Ophthalmology, Yonsei University School of Medicine, Seoul, Korea.

METHODS

In this prospective study, 27 patients with a manifest refraction of -3.00 to -6.50 diopters were treated and followed for 3 months. In each case, PRK was performed in 1 eye and LASEK in the other eye. The first eye treated and the surgical method used in the first eye were randomized. Postoperative pain, epithelial healing time, uncorrected visual acuity (UCVA), manifest refraction, corneal haze, and surgical preference were examined in PRK- and LASEK-treated eyes.

RESULTS

During the 3 month follow-up, there were no significant between-eye differences in epithelial healing time, UCVA, or refractive error. However, LASEK-treated eyes had lower postoperative pain scores (P =.047) and corneal haze scores (1 month; P =.02) than PRK-treated eyes. Seventeen patients (63%) preferred the LASEK procedure.

CONCLUSIONS

Laser epithelial keratomileusis safely and effectively treated eyes with low to moderate myopia. It reduced the incidence of significant postoperative pain and corneal haze and may prevent the flap- and interface-related problems of laser in situ keratomileusis.

Photorefractive keratectomy

In this chapter, we have reviewed important aspects of PRK. A thorough understanding of the preoperative assessments, techniques, and postoperative management is essential to achieve satisfactory visual outcomes. Laser safety checks are mandatory. A well-functioning excimer laser with good optics is required. The surgeon must avoid any decentration or global tilt. All aspects of the technique must be performed with attention to detail. The postoperative management requires frequent follow-up visits and psychological reinforcement of a healing process that is not instantaneous. PRK is a procedure in evolution. Although the results today are impressive, the complications in the future will continue to decrease with changes in lasers, techniques, and pharmacological management.

A randomized, double-masked, clinical study of the efficacy of four nonsteroidal anti-inflammatory drugs in pain control after excimer laser photorefractive keratectomy

OBJECTIVE

This study assessed the efficacy of 4 nonsteroidal anti-inflammatory drugs (NSAIDs) after excimer laser photorefractive keratectomy (PRK).

BACKGROUND

Inadequate control of pain after PRK surgery can be a severe source of distress to patients and can interfere with their willingness to undergo a second PRK procedure.

METHODS

This randomized, double-masked, placebo-controlled clinical study was conducted in 125 patients. Four NSAIDs (diclofenac, flurbiprofen, ketorolac, and indomethacin) were tested against a placebo group (artificial tears). Pain levels after PRK were quantified using Present Pain Intensity (PPI) and Pain Rating Indices based on rank values (PRI[R]) scores, both of which were calculated using patient responses to a modified McGill Pain Questionnaire. The PRI(R) consisted of 4 subscales-sensory (S), affective (A), evaluative (E), and miscellaneous (M)-as well as a total score (T).

RESULTS

Three hours after PRK, no differences in PPI scores were found between the ketorolac, diclofenac, and indomethacin groups, whereas placebo was significantly less effective than the NSAIDs. Patients who received flurbiprofen reported PPI scores that were significantly lower (P < 0.001) than those of patients who received diclofenac and indomethacin, but PPI scores in the flurbiprofen and the ketorolac groups did not differ significantly. Twenty-four hours after surgery, patients treated with flurbiprofen, ketorolac, and diclofenac reported the lowest PPI scores compared with those treated with indomethacin and placebo (P < 0.001). Moreover, flurbiprofen-treated patients also had the lowest PRI(R)T scores (P < 0.001). When the pain rating index was examined by subclass, a significantly lower PRI(R)S score was detected in the flurbiprofen group at 24 hours (P < 0.001). The PRI(R)A score was significantly higher in the placebo and indomethacin groups compared with the other groups (P < 0.001). At the 48- and 72-hour time points, flurbiprofen-treated patients again reported significantly lower PPI and PRI(R)T scores (P < 0.001 for both) in pair-wise comparisons with the other treatment groups. The number of patients who self-administered additional oral analgesics did not differ significantly between the groups. However, the mean number of analgesic tablets used was significantly higher in the placebo group than in any NSAID group (P < 0.001). The ketorolac group had the largest number of patients complaining of itching (P < 0.043). No other subjective symptoms were significantly different across groups. Finally, all NSAIDs, except flurbiprofen, prolonged the mean reepithelialization period slightly (P < 0.001).

CONCLUSIONS

Flurbiprofen appeared to be the most effective NSAID for the treatment of pain, even at 24 hours after surgery when pain was at a maximum.

Cooling effect on excimer laser photorefractive keratectomy

PURPOSE

To evaluate the effect of cooling on pain, corneal haze, and refractive outcome after excimer laser photorefractive keratectomy (PRK).

SETTING

Tokyo Medical and Dental University Hospital, Tokyo, Japan.

METHODS

The corneal surface was cooled before, during, and after laser ablation using a method called cooling PRK. Thirty-eighty highly myopic eyes of 38 patients whose spherical errors ranged from -8.00 to -18.75 diopters (D) were randomized into 2 groups: 16 eyes with conventional PRK and 22 eyes with cooling PRK. Postoperative pain was measured using the Visual Analogue Scale (VAS). Refraction, visual acuity, and complications were followed for up to 2 years. All data were analyzed and compared between groups to evaluate the cooling effect on PRK.

RESULTS

One day postoperatively, patients in the cooling PRK group had significantly less pain (P < .01). At 3 months, the haze score in the cooling PRK group was significantly less than in the conventional PRK group (P < .01). The residual refractive error was not significantly different between the 2 groups until 2 years, when it was greater in the conventional PRK (mean -5.09 D +/- 2.11 [SD]) than the cooling PRK group (-4.64 +/- 2.27 D). Ten eyes (62.5%) in the conventional PRK group and 15 eyes (68.2%) in the cooling PRK group were within +/- 1.00 D of the intended refraction. There were no serious complications in the cooling PRK group. Two eyes in the conventional PRK group had severe corneal haze and lost 2 Snellen lines of best corrected visual acuity.

CONCLUSION

Corneal cooling on PRK effectively reduced postoperative pain, corneal haze, and myopic regression.

The placebo effect

Placebos have been traditionally regarded as deceptive therapies and have not been understood in the broader context of social symbols and of interpersonal factors that surround the healing process itself. Although the power of inert substances to heal is well recognized, the placebo effect also influences the outcome of conventional therapies. The role of the placebo in modern medicine is poorly defined because of a lack of a common understanding of what the placebo effect is and because of the negative connotions associated with its use. The response rate to placebo varies by illness. The natural course of disease and patient or physician bias can be misinterpreted as a placebo response. In research, the placebo effect is therapeutic noise to be removed by placebo-controlled trials. Few studies are designed to measure the placebo response rate directly. Placebos are a reminder of how little is known about mind-body interaction. The placebo effect may be one of the most versatile and underused therapeutic tools at the disposal of physicians.

Comparison of the effectiveness of 4 anti-inflammatory drops in relieving photophobia after pupil dilation

PURPOSE

To compare the relative effectiveness of diclofenac, flurbiprofen, ketorolac, and prednisolone acetate in relieving photophobia after pupil dilation for fundus examination.

SETTING

Eye, Ear, Nose, and Throat Hospital, New Orleans, Louisiana, USA.

METHODS

This prospective, blind, placebo-controlled study comprised 105 patients randomly assigned to 1 of 10 treatment groups. Five minutes after instillation of dilating drops, each patient received drops of different test medications in the right and left eyes. Light sensitivity and pupil measurement tests were performed over 2 hours after the pharmacological mydriasis. After photostimulation, patients were asked to rate their photosensitivity on numerical and analog scales and to indicate a filter value required to alleviate right-induced discomfort. Test results were analyzed to detect differences among the pain levels associated with each treatment.

RESULTS

There were no significant differences between the placebo and any active treatment drug at any time during the study.

CONCLUSION

These findings suggest that mediators other than prostaglandins may have a role in photosensitivity or that increased postmydriatic photosensitivity is a result of higher light levels entering the eye through the dilated pupil.

Corneal penetration of diclofenac from a fixed combination of diclofenac-gentamicin eyedrops

PURPOSE

To establish the corneal penetration of diclofenac in the presence of gentamicin in patients having cataract surgery.

SETTING

Kantonsspital Augenklinik, Aarau, and Hôpital Jules Gonin, Lausanne, Switzerland.

METHODS

Eligible patients having cataract surgery (39 women, 30 men) were treated with 4 drops of diclofenac 0.1%-gentamicin 0.3% (Voltamicin) instilled at 20 minute intervals. Paracentesis was performed 15, 30, or 60 minutes after the last instillation, and a sample of aqueous humor was collected for analysis of diclofenac by high-performance liquid chromatography. Blood samples of some patients were obtained before surgery for analysis.

RESULTS

Mean diclofenac levels (+/- SD) in the aqueous humor 15, 30, and 60 minutes after the last instillation were 72 +/- 84, 108 +/- 87, and 201 +/- 116 ng/mL (= 682 nMol/L), respectively. Diclofenac remained below the limit of detection (5 ng/mL) in all samples of blood serum. In general, local tolerance was good; no side effects were reported. Comparison of the data with published results of topically instilled diclofenac 0.1% suggests that the concentration of diclofenac in the aqueous humor achieved with 4 instillations of the combination product is similar to that achieved with 8 instillations of diclofenac 0.1% (Voltaren Ophtha) alone.

CONCLUSIONS

Drug levels of diclofenac in the aqueous humor well above IC-50 for cyclo-oxygenase were achieved with the regimen applied. No inhibitory effect by the gentamicin or vehicle was observed. Comparison of these data with published results of Voltaren Ophtha implies a 2-fold better penetration of diclofenac with the diclofenac-gentamicin combination.

Comparative study of the analgesic efficacy of flurbiprofen and diclofenac in patients following excimer laser photorefractive keratectomy

This randomized, patient-masked, crossover trial compared the analgesic efficacy of flurbiprofen and diclofenac in 16 patients following excimer laser photorefractive keratectomy. Patients were randomly assigned to receive one study medication after surgery on the first eye and the other medication after surgery on the second eye (approximately 30 days later). After both surgeries, patients instilled one drop of the assigned medication six times daily for the first 3 days postsurgery and one drop four times daily on postsurgery days 4 through 7. Patients assessed the intensity of postsurgical pain beginning at postsurgery hour 5 and pain relief beginning at postsurgery hour 8 and continued to do so daily thereafter. On the last day (day 7), patients rated the global efficacy of the analgesic treatment. All assessments were performed by patients using descriptor and visual ordinal scales and were recorded in diaries. Patients were queried as to the presence, severity, and duration of any adverse events. Flurbiprofen produced significantly greater reductions in pain intensity than did diclofenac at all evaluations through day 4 and significantly greater relief of pain than did diclofenac at all evaluations through day 3. Significantly more patients treated with flurbiprofen reported being pain free on days 3 and 4 (11 [69%] and 16 [100%], respectively) compared with those treated with diclofenac (3 [19%] and 9 [56%], respectively). Based on patient ratings, flurbiprofen had significantly better global analgesic activity than diclofenac. Both treatments were well tolerated. Mild and transient ocular burning after instillation was the only reported adverse event; it was reported by all patients in both study groups at approximately 50% of study visits.

Experimental study of tetrodotoxin, a long-acting topical anesthetic

PURPOSE

To determine the effectiveness and toxicity of tetrodotoxin for use as a long-acting topical anesthetic.

METHODS

Four groups of six rabbits each received a 40-microl aliquot of either tetrodotoxin in one of three concentrations (10 mM, 1 mM, or 0.1 mM) or proparacaine 0.5% into the inferior conjunctival cul-de-sac of one eye, with the fellow eye of each rabbit receiving 40 microl of a 60-mM, pH 4.3 sodium citrate vehicle as a control. Corneal sensation was tested for up to 8 hours after administration of drugs, and response was noted by no blink, partial blink without full eyelid closure, and full blink. Slit-lamp examination at 12 and 24 hours after administration and pachymetry before and 24 hours after administration were performed to detect corneal toxicity.

RESULTS

Rabbits receiving all three concentrations of tetrodotoxin did not demonstrate any ocular irritation, corneal thickening, or signs of systemic toxicity. At a dose of 10 mM, tetrodotoxin produced an anesthetic effect lasting up to 8 hours. At 1 mM, tetrodotoxin was an effective but shorter-acting anesthetic. At 0.1 mM, tetrodotoxin had no significant anesthetic effect. Proparacaine-treated rabbits initially were anesthetic, but this effect was largely gone by 1 hour and completely gone by 3 hours.

CONCLUSIONS

Tetrodotoxin is a long-acting topical anesthetic in the rabbit cornea. Although additional toxicity studies are required, tetrodotoxin may provide an effective, long-lasting topical anesthetic for use in pain control after corneal procedures such as photorefractive keratectomy.

Laser in situ Keratomileusis for Myopia of -1 to -3.50 Diopters

BACKGROUND

Laser in situ keratomileusis (LASIK) is the procedure of choice for high myopia. We present a study of 85 eyes undergoing LASIK for myopia between -1.00 and -3.50 diopters (D) and assess the safety and efficacy of the procedure for treatment of low myopia.

METHODS

Eighty-five eyes of 47 patients with a mean age of 29 years, (range, 18 to 56 yrs) underwent LASIK using the Chiron microkeratome and the Nidek EC-5000 excimer laser. Mean preoperative myopia was -2.09 D and mean astigmatism was 0.86 D. All other ocular pathology was ruled out before surgery. Mean follow-up was 48 days (range, 1 day to 13 mo).

RESULTS

Uncorrected visual acuity of 6/9 or better at 1 week was achieved in 44 eyes (52%); at 1 month in 68 eyes (80%); and at 6 months in 70 eyes (93%). Pain score was minimal with the majority of patients having no postoperative pain. One eye suffered a serious postoperative complication of corneal abscess which resolved with treatment, but left a corneal scar and visual acuity of 6/60.

CONCLUSION

LASIK is a safe and effective procedure for low amounts of myopia; it also provides early visual rehabilitation and markedly reduced pain and discomfort to patients undergoing refractive surgery.

Dilute topical proparacaine for pain relief after photorefractive keratectomy

PURPOSE

The purpose of the study is to determine whether there is a nonanesthetic and nontoxic concentration of topical proparacaine that can be applied repeatedly to the cornea to reduce pain after photorefractive keratectomy (PRK).

METHODS

Part I: To determine a nonanesthetic concentration, the corneal sensitivity of 50 healthy volunteers was assessed using aesthesiometry before and after a drop of either 0.01%, 0.025%, 0.05%, 0.1%, or 0.2% topical proparacaine. Ten volunteers similarly were tested with multiple doses of 0.05% proparacaine. To evaluate toxicity, ten healthy volunteers self-administered 0.05% proparacaine to one eye and placebo to the other eye every 15 minutes for 12 hours on day 1 and every hour for 12 hours on days 2 through 7. Subjects were assessed throughout the week using visual acuity, slitlamp examination, aesthesiometry, and ultrasonic pachometry. Part II: In a prospective, double-masked study, 34 patients who underwent PRK (48 eyes) self-administered either topical 0.05% proparacaine or placebo for 1 week after PRK as needed to reduce pain. Patients recorded their pain score before and after drop use and answered a pain-relief questionnaire.

RESULTS

Part I: Proparacaine concentrations greater than or equal to 0.1% eliminated sensation from some corneas; concentrations of less than or equal to 0.05% were never fully anesthetic. No corneal toxicity was observed except for some minimal punctate staining in both treatment and placebo eyes. Part II: Patients in the treatment group had significantly more pain relief (P < 0.001) for a longer period (P < 0.001) than did patients in the control group. Average change in pain score was significantly greater in the treatment group (P < 0.002). No significant difference in the number of days needed to reach complete epithelial healing was found between the two groups (P < 0.18).

CONCLUSIONS

Dilute (0.05%) topical proparacaine is nonanesthetic and nontoxic, and can be used safely for at least 1 week to reduce pain after PRK.

Topical Diclofenac Sodium after Excimer Laser Phototherapeutic Keratectomy

BACKGROUND

Both the potential analgesic effects and side-effects of topical diclofenac sodium 0.1% are points of interest after excimer laser phototherapeutic keratectomy.

METHODS

Excimer laser phototherapeutic keratectomy was performed in 134 eyes of 134 patients. In 65 eyes (65 patients), the effects of topical diclofenac given three times a day for 3 to 4 days were compared to a control group of 69 eyes (69 patients). All patients received paracetamol for systemic analgesia and were patched after surgery until reepithelialization.

RESULTS

Twenty-eight patients (43%) of the diclofenac group needed additional systemic analgesics compared to 67 patients (95%) in the control group. Seventy-two hours after surgery we found no significant differences in corneal epithelial wound healing and no severe complications.

CONCLUSION

Topical diclofenac sodium reduces postoperative pain in patients after phototherapeutic keratectomy.