Pharmacotherapy of 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.

Antifibrotic Effects of Caffeine, Curcumin and Pirfenidone in Primary Human Keratocytes

We evaluated the small molecules (AFM) caffeine, curcumin and pirfenidone to find non-toxic concentrations reducing the transformation of activated human corneal stromal keratocytes (aCSK) to scar-inducing myofibroblasts (MYO-SF). CSK were isolated from 16 human corneas unsuitable for transplantation and expanded for three passages in control medium (0.5% FBS). Then, aCSK were exposed to concentrations of caffeine of 0−500 μM, curcumin of 0−200 μM, pirfenidone of 0−2.2 nM and the profibrotic cytokine TGF-β1 (10 ng/mL) for 48 h. Alterations in viability and gene expression were evaluated by cell viability staining (FDA/PI), real-time polymerase chain reaction (RT-PCR) and immunocytochemistry. We found that all AFMs reduced cell counts at high concentrations. The highest concentrations with no toxic effect were 100 µM of caffeine, 20 µM of curcumin and 1.1 nM of pirfenidone. The addition of TGF-β1 to the control medium effectively transformed aCSK into myofibroblasts (MYO-SF), indicated by a 10-fold increase in α-smooth muscle actin (SMA) expression, a 39% decrease in lumican (LUM) expression and a 98% decrease in ALDH3A1 expression (p < 0.001). The concentrations of 100 µM of caffeine, 20/50 µM of curcumin and 1.1 nM of pirfenidone each significantly reduced SMA expression under TGF-β1 stimulation (p ≤ 0.024). LUM and ALDH3A1 expression remained low under TGF-β1 stimulation, independently of AFM supplementation. Immunocytochemistry showed that 100 µM of caffeine, 20 µM of curcumin and 1.1 nM of pirfenidone reduce the conversion rate of aCSK to SMA+ MYO-SF. In conclusion, in aCSK, 100 µM of caffeine, 20 µM of curcumin and 1.1 nM of pirfenidone significantly reduced SMA expression and MYO-SF conversion under TGF-β1 stimulation, with no influence on cell counts. However, the AFMs were unable to protect aCSK from characteristic marker loss.

The Effectiveness and Safety of Dextenza 0.4 mg for the Treatment of Postoperative Inflammation and Pain in Patients After Photorefractive Keratectomy: The RESTORE Trial

PURPOSE

To determine patient preference and treatment outcomes with an intracanalicular dexamethasone 0.4 mg insert compared to a standard steroid drop regimen in the contralateral eye following bilateral photorefractive keratectomy (PRK).

METHODS

In this randomized, prospective, self-controlled, open-label interventional study, one eye received the dexamethasone insert and the second eye received prednisolone acetate 1% taper following bilateral PRK surgery. Postoperative evaluations were performed on day 3, day 4, month 1, and month 3. Phone call surveys were performed on week 2. The Comparison of Ophthalmic Medications for Tolerability questionnaire was used to determine patient preference between postoperative regimens and postoperative pain. Corneal endpoints included time to epithelialization, presence of corneal haze, sodium fluorescein staining, and modified Standardized Patient Evaluation of Eye Dryness (SPEED) scores. Both corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA) were assessed.

RESULTS

Twenty patients participated in the study. At month 3, 70% of patients preferred the dexamethasone insert, 20% preferred prednisolone acetate, and 10% expressed no preference. Patient surveys did not show a difference in postoperative pain between the study group and control group. No statistical difference was shown in time to epithelialization, 90-day CDVA or UDVA, postoperative corneal haze, corneal staining, or modified SPEED scores.

CONCLUSIONS

In patients undergoing PRK, there was preference toward a dexamethasone insert in place of topical prednisolone acetate for the postoperative steroid treatment. There were no statistically or clinically significant differences between the two cohorts in regard to healing time or visual outcomes. [J Refract Surg. 2021;37(9):590-594.].

Dexamethasone-Eluting Contact Lens for the Prevention of Postphotorefractive Keratectomy Scar in a New Zealand White Rabbit Model

PURPOSE

To evaluate the safety and efficacy of an experimental dexamethasone-eluting contact lens (DCL) for the prevention of postphotorefractive keratectomy (PRK) corneal haze in a New Zealand White (NZW) rabbit model.

METHODS

Both eyes of 29 NZW rabbits underwent PRK. The rabbits were randomized to one of the 5 study arms for 4 weeks: tarsorrhaphy only, tarsorrhaphy and bandage contact lens (BCL) replaced weekly, tarsorrhaphy and BCL for 1 week plus topical 0.1% dexamethasone ophthalmic solution (drops) for 4 weeks, tarsorrhaphy and BCL replaced weekly plus topical dexamethasone for 4 weeks, and tarsorrhaphy and DCL changed weekly for 4 weeks. Each week for 4 consecutive weeks postoperatively, the tarsorrhaphies were opened, the eyes underwent evaluation and imaging, and the tarsorrhaphies were replaced. Contact lenses were cultured on removal. Central corneal haze was assessed weekly with corneal densitometry. After 4 weeks, the animals were killed, and the eyes were enucleated for histopathologic analysis.

RESULTS

The tarsorrhaphy only group displayed more haze with a greater change in optical densitometry from pre-op compared with the other treatment groups. There was no difference between the DCL group and the groups receiving a BCL and dexamethasone drops in densitometry or histopathology. No NZW rabbits developed clinical signs of infection, and cultures from DCLs and BCLs grew similar organisms.

CONCLUSIONS

In the post-PRK rabbit model, DCLs worn weekly for 4 weeks were safe and as effective at preventing corneal haze as 0.1% dexamethasone drops applied 4 times a day for 4 weeks.

Preferred practice patterns for photorefractive keratectomy surgery

Over the past two decades, excimer laser-based refractive surgery procedures have been successfully established for their safety and satisfactory visual outcomes. Surface ablation procedures or photorefractive keratectomy (PRK) are practised commonly for the correction of refractive errors including myopia, astigmatism and hyperopia. Satisfactory visual outcomes are achieved in majority of cases, although a very small percentage have issues related to corneal haze, regression, and its associated visual disturbances. To ensure optimal outcomes and to minimize complications, certain keys to success have been designed on the basis of the current review of literature on surface ablation procedures.

Duration of topical steroid application after photorefractive keratectomy with mitomycin C

Contradictory results of postoperative steroid application in photorefractive keratectomy (PRK) led to a meta-analysis of the existing data to achieve a definite conclusion on the optimum dosage and duration of corticosteroid therapy after PRK. The overall pooled unstandardized mean difference (PUMD) of the corneal haze score was -0.20 (95% CI, -0.29 to -0.12). In subgroup analysis, the PUMD of the corneal haze score was statistically significant in 2 subgroups, -0.57 (-0.85 to -0.30) for 3 to 6 months postoperatively and -0.13 (-0.23 to -0.04) for ≤ 3 months postoperatively. Analysis of the PUMD of postoperative spherical equivalent in participants with low to moderate myopia (≥-6.00 D) and high myopia (<-6.00 D) showed positive effects of steroids on prevention of myopia regression. In conclusion, long-term topical steroid application after PRK seems unnecessary in low and moderate myopia. New randomized clinical trials using current technologies are recommended for postoperative treatments.

Comparison of the effect of cycloplegic versus NSAID eye drops on pain after photorefractive keratectomy

PURPOSE

To compare the effect of Homatropine and Diclofenac eye drops for reducing pain after photorefractive keratectomy (PRK).

METHODS

This randomized, double-masked, interventional study included 32 patients (64 eyes) who underwent bilateral PRK. After operation, patients received Homatropine eye drops in one eye and Diclofenac eye drops in the fellow eye for 48 h. The level of pain was evaluated using visual analogue scale (VAS), verbal rating scale (VRS), and pain rating index (PRI) at 0.5, 24, and 48 h after operation.

RESULTS

The level of pain was statistically similar between the two eyes half an hour after operation; however, Diclofenac eyes had significantly less pain 24 h after operation (1.7 ± 1.4 vs 5.8 ± 2.1, P < 0.001 for VAS, 0.6 ± 0.6 vs 2.4 ± 1.1, P < 0.001 for VRS, and 3.4 ± 3.4 vs 12.0 ± 6.9, P < 0.001 for PRI, respectively). Also, 48 h after surgery, the pain scores were less in the Diclofenac eyes (1.6 ± 1.8 vs 3.4 ± 2.8, P < 0.001 for VAS, 0.6 ± 0.6 vs 1.2 ± 0.9, P < 0.001 for VRS, and 3.3 ± 3.7 vs 6.5 ± 6.2, P < 0.001 for PRI). No case with delayed epithelial healing in both groups was observed.

CONCLUSION

The effect of Homatropine seems to be lower compared to Diclofenac for reducing pain after photorefractive keratectomy.

Reversal of fibrosis by TGF-β3 in a 3D in vitro model

Corneal scarring following moderate to severe injury is inevitable. Despite significant advancements in the field, current treatments following these types of injuries are limited, and often, the visual recovery is poor. One of the problems and limitations is that corneal wound healing is a complex process, involving corneal cells, extracellular matrix components and growth factors. Therefore, further understanding is required, along with new treatments and techniques to reduce or prevent corneal scarring following injury. Two isoforms of transforming growth factor-beta (TGF-β), TGF-β1 and -β3 (T1 and T3, respectively), are associated with corneal wound healing. T1 has been shown to drive the corneal keratocytes to differentiate into myofibroblasts; whereas, T3 has been found to inhibit fibrotic markers. In the current study, we examined whether the fibrotic characteristics expressed by human corneal fibroblasts (HCF) in our 3-dimensional (3D) construct following T1 stimulation could be reversed by introducing T3 to the in vitro system. To do this, HCF were isolated and cultured in 10% serum, and when they reached confluence, the cells were stimulated with a stable Vitamin C (VitC) derivative for 4 weeks, which allowed them to secrete a self-assembled matrix. Three conditions were tested: (1) CONTROL: 10% serum (S) only, (2) T1: 10%S + T1, or (3) Rescue: 10%S + T1 for two weeks and then switched to 10%S + T3 for another two weeks. At the end of 4 weeks, the constructs were processed for analysis by indirect-immunofluorescence (IF) and transmission electron microscopy (TEM). Different collagens that are normally present in healthy corneas in vivo, such as Type I and V, as well as Type III, which is a fibrotic indicator, were examined. In addition, we examined smooth muscle actin (SMA), a marker of myofibroblasts, and thrombospondin-1 (TSP-1), a multifunctional matrix protein known to activate the latent complex of TGF-β and appear upon wounding in vivo. Our data showed high expression of collagens type I and V under all conditions throughout the 3D constructs; however, type III and SMA expression were higher in the constructs that were stimulated with T1 and reduced to almost nothing in the Rescue samples. A similar pattern was seen with TSP-1, where TSP-1 expression following "rescue" was decreased considerably. Overall, this data is in agreement with our previous observations that T3 has a significant non-fibrotic effect on HCFs, and presents a novel model for the "rescue" of both cellular and matrix fibrotic components with a single growth factor.

Topical rosiglitazone is an effective anti-scarring agent in the cornea

Corneal scarring remains a major cause of blindness world-wide, with limited treatment options, all of which have side-effects. Here, we tested the hypothesis that topical application of Rosiglitazone, a Thiazolidinedione and ligand of peroxisome proliferator activated receptor gamma (PPARγ), can effectively block scar formation in a cat model of corneal damage. Adult cats underwent bilateral epithelial debridement followed by excimer laser ablation of the central corneal stroma to a depth of ~160 µm as a means of experimentally inducing a reproducible wound. Eyes were then left untreated, or received 50 µl of either 10 µM Rosiglitazone in DMSO/Celluvisc, DMSO/Celluvisc vehicle or Celluvisc vehicle twice daily for 2 weeks. Cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and post-mortem immunohistochemistry for alpha smooth muscle actin (αSMA). Impacts of the wound and treatments on optical quality were assessed using wavefront sensing and optical coherence tomography at 2, 4, 8 and 12 weeks post-operatively. In parallel, cat corneal fibroblasts were cultured to assess the effects of Rosiglitazone on TGFβ-induced αSMA expression. Topical application of Rosiglitazone to cat eyes after injury decreased αSMA expression and haze, as well as the induction of lower-order and residual, higher-order wavefront aberrations compared to vehicle-treated eyes. Rosiglitazone also inhibited TGFβ-induced αSMA expression in cultured corneal fibroblasts. In conclusion, Rosiglitazone effectively controlled corneal fibrosis in vivo and in vitro, while restoring corneal thickness and optics. Its topical application may represent an effective, new avenue for the prevention of corneal scarring with distinct advantages for pathologically thin corneas.

Effect of Homatropine eye drops on pain after photorefractive keratectomy: A pilot study

PURPOSE

To assess the effect of homatropine eye drops on pain after photorefractive keratectomy (PRK).

METHODS

This randomized, double masked, interventional study included 15 patients (30 eyes) who underwent bilateral PRK. After operation, patients received homatropine eye drops, 4 times daily in only one eye (homatropine eye). The level of pain was evaluated using visual analogue scale (VAS), verbal rating scale (VRS) and pain rating index (PRI) at 0.5, 24 and 48 h after operation.

RESULTS

The level of pain was statistically similar between the two eyes half an hour after operation, however, homatropine eyes had significantly less pain 24 h after operation compared to fellow eyes (2.5 ± 1.9 vs 5.3 ± 2.5, P = 0.004 for VAS, 2.0 ± 1.2 vs 3.2 ± 0.9, P = 0.023 for VRS, and 9.4 ± 5.7 vs 16.0 ± 9.0, P = 0.031 for PRI). Also, 48 h after surgery, the pain scales were less in the homatropine eyes (2.3 ± 1.7 vs 4.0 ± 2.1, P = 0.014 for VAS, 1.6 ± 1.0 vs 2.5 ± 1.0, P = 0.038 for VRS, and 6.8 ± 5.7 vs 12.0 ± 8.9, P = 0.005 for PRI). No delayed epithelial healing was observed.

CONCLUSION

Homatropine eye drops may be useful for reducing pain after Photorefractive keratectomy.

Estudo clínico e histológico das pálpebras e conjuntiva hígidas submetidas ao tratamento tópico com soluções anestésicas em coelhos

Avaliaram-se as apresentações comerciais de colírios anestésicos aplicados em 63 coelhos da raça Nova Zelândia, distribuídos em três grupos (G1, G2 e G3) de 21 animais cada e que receberam instilação de uma gota em cada olho seis vezes ao dia. Os animais do G1 foram tratados com colírio de cloridrato de proparacaína a 0,5%; os do G2, com colírio de cloridrato de tetracaína a 1% associado à fenilefrina a 0,1%; e os do G3, com solução fisiológica. Cada grupo foi subdividido em três subgrupos com sete animais cada, os quais foram tratados por três, sete e 15 dias. No final de cada tratamento, dois animais de cada subgrupo foram sacrificados para exame histológico de fragmentos retirados da conjuntiva, da terceira pálpebra e das pálpebras. Observou-se, ao exame clínico, episclerite em graus diversos em 100% dos animais do G1, no terceiro, sétimo e 15º dia, e em apenas 17,8% nos do G2, nestes mesmos dias. Ao exame microscópico, observaram-se aumento do número de células califormes, proliferação de folículos linfoides, aumento do número de eosinófilos e aumento do espaço intersticial nas pálpebras dos animais do G1. Pôde-se concluir que o colírio de tetracaína a 1% associado à fenilefrina a 0,1% promoveu maior toxicidade à conjuntiva ocular e às pálpebras de coelhos quando comparado ao colírio de proparacaína a 0,5%.

Topical analgesics in the management of acute and chronic pain

Oral analgesics are commonly prescribed for the treatment of acute and chronic pain, but these agents often produce adverse systemic effects, which sometimes are severe. Topical analgesics offer the potential to provide the same analgesic relief provided by oral analgesics but with minimal adverse systemic effects. This article describes the results of a systematic review of the efficacy of topical analgesics in the management of acute and chronic pain conditions. A literature search of MEDLINE/PubMed was conducted using the keywords topical analgesic AND chronic pain OR acute pain OR neuropathic pain and focused only on individual clinical trials published in English-language journals. The search identified 92 articles, of which 65 were eligible for inclusion in the review. The most commonly studied topical analgesics were nonsteroidal anti-inflammatory drugs (n=27), followed by lidocaine (n=9), capsaicin (n=6), amitriptyline (n=5), glyceryl trinitrate (n=3), opioids (n=2), menthol (n=2), pimecrolimus (n=2), and phenytoin (n=2). The most common indications were acute soft tissue injuries (n=18), followed by neuropathic pain (n=17), experimental pain (n=6), osteoarthritis and other chronic joint-related conditions (n=5), skin or leg ulcers (n=5), and chronic knee pain (n=2). Strong evidence was identified for the use of topical diclofenac and topical ibuprofen in the treatment of acute soft tissue injuries or chronic joint-related conditions, such as osteoarthritis. Evidence also supports the use of topical lidocaine in the treatment of postherpetic neuralgia and diabetic neuropathy. Currently, limited evidence is available to support the use of other topical analgesics in acute and chronic pain.

The incidence of central serous chorioretinopathy after photorefractive keratectomy and laser in situ keratomileusis

Purpose. To assess the incidence of central serous chorioretinopathy (CSCR) following laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Methods. A chart review was performed to identify all patients with CSCR and a previous history of LASIK or PRK. Results. Over the 6-year study period, 1 of 4,876 eyes which had LASIK or PRK at the Moran Eye Center was diagnosed with CSCR. One other patient was referred from an outside center, developed CSCR symptoms one month after PRK. Both patients were managed conservatively with a final visual acuity of 20/20 or better. All other patients presented 4 or more years after refractive surgery. Conclusions. We report the first 2 CSCR cases developing within one month after PRK. The low incidence argues against a causal association. Topical corticosteroids or anxiety may elevate cortisol levels presenting therapeutic challenges for the management of CSCR after PRK or LASIK.

Infectious keratitis in 18,651 laser surface ablation procedures

PURPOSE

To evaluate the incidence, culture results, risk factors, treatment strategies, and visual outcomes of infectious keratitis after surface ablation.

SETTING

Multicenter study in Spain.

DESIGN

Case series.

METHODS

The medical records of patients who had surface ablation between January 2003 and December 2009 were reviewed to identify cases of infectious keratitis. The incidence, risk factors, clinical course, days to diagnosis, medical and surgical treatment, and visual outcome were recorded. Main outcome measures were incidence of infectious keratitis after surface ablation, culture results, response to treatment, and visual outcomes.

RESULTS

The study reviewed the records of 9794 patients (18,651 eyes). Infectious keratitis after surface ablation was diagnosed in 39 eyes of 38 patients. The onset of infection was early (within 7 days after surgery) in 28 cases (71.79%). Cultures were positive in 13 of 27 cases in which samples were taken. The most frequently isolated microorganism was Staphylococcus species (9 cases). The final corrected distance visual acuity (CDVA) was 20/20 or better in 23 cases (58.97%), 20/40 or better in 36 cases (92.30%), and worse than 20/40 in 3 cases (7.69%).

CONCLUSIONS

The incidence of infectious keratitis after surface ablation was 0.20%. Infectious keratitis is a potentially vision-threatening complication. Prompt and aggressive management with an intensive regimen of fortified antibiotic agents is strongly recommended. Proper management can preserve useful vision in most cases.

FINANCIAL DISCLOSURE

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

Reducing peak corneal haze after photorefractive keratectomy in rabbits: prednisolone acetate 1.00% versus cyclosporine A 0.05%

PURPOSE

To compare the effects of topical cyclosporine A 0.05% (Restasis) with those of prednisolone acetate 1.00% (Pred Forte) on corneal haze after photorefractive keratectomy (PRK).

SETTING

Gavin Herbert Eye Institute, University of California, Irvine-Orange, California, USA.

DESIGN

Experimental study.

METHODS

After -9.00 diopter PRK, 15 rabbits were divided into 3 groups and treated for 4 weeks with prednisolone acetate 1.00% or cyclosporine A 0.05% or neither (control). Corneal haze was measured by in vivo confocal microscopy preoperatively and 2, 4, 6, 8, and 12 weeks postoperatively. At 12 weeks, the corneas were evaluated for collagen organization by ex vivo 2-photon second-harmonic generation and stromal cell density.

RESULTS

Corneal haze was significantly less in the prednisolone acetate group than in the cyclosporine and control groups during the first 6 weeks postoperatively (P<.02). At 8 weeks, there was no significant difference between the 3 groups. There was no significant difference in haze between the cyclosporine and control groups at any time. The stroma was also significantly thinner in the prednisolone acetate group than in the other groups for the first 4 weeks postoperatively (P<.02). Second-harmonic generation scar thickness measurements at 12 weeks were not significantly different between the groups, although the prednisolone acetate group tended to have lower stromal cell density.

CONCLUSION

Cyclosporine A 0.05% had no effect on wound healing after PRK, while prednisolone acetate 1.00% significantly reduced peak corneal haze but had no effect on long-term corneal haze after discontinuation of the drug.

Optical effects of anti-TGFbeta treatment after photorefractive keratectomy in a cat model

PURPOSE

To assess the contribution of corneal myofibroblasts to optical changes induced by photorefractive keratectomy (PRK) in a cat model.

METHODS

The transforming growth factor (TGF)-beta-dependence of feline corneal keratocyte differentiation into alpha-smooth muscle actin (alphaSMA)-positive myofibroblasts was first tested in vitro. Twenty-nine eyes of 16 cats were then treated with -10 D PRK in vivo and divided into two postoperative treatment groups that received either 100 microg anti-TGFbeta antibody for 7 days, followed by 50 microg dexamethasone for another 7 days to inhibit myofibroblast differentiation, or vehicle solution for 14 days (control eyes). Corneal thickness and reflectivity were measured by optical coherence tomography. Wavefront sensing was performed in the awake-behaving state before surgery and 2, 4, 8, and 12 weeks after surgery. Wound healing was monitored using in vivo confocal imaging and postmortem alphaSMA immunohistochemistry.

RESULTS

In culture, TGFbeta caused cat corneal keratocytes to differentiate into alphaSMA-positive myofibroblasts, an effect that was blocked by coincubation with anti-TGFbeta antibody. In vivo, anti-TGFbeta treatment after PRK resulted in less alphaSMA immunoreactivity in the subablation stroma, lower corneal reflectivity, less stromal regrowth, and lower nonspherical higher order aberration induction than in control eyes. However, there were no intergroup differences in epithelial regeneration or lower order aberration changes.

CONCLUSIONS

Anti-TGFbeta treatment reduced feline corneal myofibroblast differentiation in vitro and after PRK. It also decreased corneal haze and fine-grained irregularities in ocular wavefront after PRK, suggesting that attenuation of the differentiation of keratocytes into myofibroblast can significantly enhance optical quality after refractive surface ablations.

Effects of acetylcysteine and dexamethasone on experimental corneal wounds in rabbits

Corneal wound healing often leads to the development of scar tissue with loss of transparency. Reconstitution of transparent corneal stroma depends on the regulation of the biosynthetic activities of post-lesional keratocytes as well as to a large extent on the limitation of matrix degradation. It has been shown that 3% concentration of N-acetylcysteine (NAC) improves the healing time of corneal wounds but some corneal haze remains. On the other hand, topical corticosteroids may retard the corneal wound healing but decrease the haze. Thus, the aim of the study was to evaluate whether adding dexamethasone to NAC could reduce the side effects of the two drugs. In this study, experimental corneal wounds were created surgically, up to the depth of one half of the stroma in the center of both eyes of all rabbits. The left eyes were treated topically with 0.9% NaCl as controls and the right eyes were treated with a combination of one drop of 3% NAC and one drop of 0.1% dexamethasone, 6 times per day. Corneal wounds were measured by fluorescein staining every day. The results indicated that the combination of acetylcysteine and dexamethasone significantly increased the mean healing time compared to the control group (p < 0.05). Clinical and histopathologic examinations revealed that the corneal haze in the treatment group was greater than in the control group. It is concluded that treatment of the eyes by a combination of 3% acetylcysteine and 0.1% dexamethasone (if used from the first day of ulceration) may retard the corneal wound healing in rabbits.

Effects of nonsteroidal ophthalmic drops on epithelial healing and pain in patients undergoing bilateral photorefractive keratectomy (PRK)

The present study, which was designed as a prospective, double-masked, randomized, controlled, single-site study, was conducted to compare the effects of 3 approved ophthalmic nonsteroidal anti-inflammatory drugs-nepafenac ophthalmic suspension 0.1% (Nevanac; Alcon Laboratories, Inc., Fort Worth, Tex), ketorolac tromethamine ophthalmic solution 0.4% (Acular LS; Allergan, Irvine, Calif), and bromfenac 0.09% (Xibromtrade mark; ISTA Pharmaceuticals, Irvine, Calif)-on corneal reepithelialization and postoperative pain control in patients undergoing photorefractive keratectomy. In addition to nonsteroidal anti-inflammatory drugs, each patient received an antibiotic-moxifloxacin hydrochloride ophthalmic solution 0.5% (nepafenac group) or gatifloxacin ophthalmic solution 0.3% (ketorolac and bromfenac groups). All treatments were administered 3 times daily beginning 1 d preoperatively and continuing for 1 wk postoperatively; prednisolone acetate 1.0% was administered concurrently 4 times daily. Bandage contact lenses were replaced at each postoperative visit for corneal staining and epithelial defect grading. Self-evaluation of pain relief was recorded on postoperative days 1 and 3 with the use of a visual analog scale. A total of 29 patients (58 eyes) were enrolled and underwent bilateral custom photorefractive keratectomy. Mean time to reepithelialization was 5.50+/-1.59 d for the nepafenac 0.1% group, 5.62+/-1.23 d for the ketorolac 0.4% group, and 7.25+/-2.53 d for the bromfenac 0.09% group. A significant difference was detected between nepafenac 0.1% and bromfenac 0.09% and between ketorolac 0.4% and bromfenac 0.09% (P<.05). Significant reductions in pain scores were observed with nepafenac 0.1% on day 1 (-1.13) and day 3 (-1.32), ketorolac 0.4% on day 3 (-0.88), and bromfenac 0.09% on day 3 (-0.83). No adverse events were reported. Eyes treated with nepafenac 0.1% or ketorolac 0.4% achieved complete reepithelialization significantly faster than those treated with bromfenac 0.09%. Daily contact lens removal and application of fluorescein may have delayed reepithelialization in the overall population; however, the effect would have been the same in all 3 groups. Pain relief with nepafenac 0.1% was achieved sooner than with ketorolac 0.4% or bromfenac 0.09%.

Double-masked study of the effects of nepafenac 0.1% and ketorolac 0.4% on corneal epithelial wound healing and pain after photorefractive keratectomy

Two NSAIDs--nepafenac 0.1% and ketorolac tromethamine 0.4%-were compared in terms of their effects on corneal reepithelialization and pain after photorefractive keratectomy (PRK) in a randomized, double-masked, contralateral eye, multicenter study. A total of 40 healthy adult patients who were undergoing sequential bilateral PRK received nepafenac 0.1% and ketorolac 0.4% in contralateral eyes, 1 drop 3 times daily for 3 d after bandage contact lens insertion. Patients were assessed on postoperative days 1, 3, 4, 5, and 7. At each visit, patients provided a general rating of pain. Each patient also assessed the sensation of each eyedrop following instillation (after-drop pain, irritation, burning/stinging, and overall comfort). Starting on day 3, epithelial defect size was assessed. Mean epithelial defect size was similar between treatments at each postoperative visit (P>.05). The average time-to-healing was 4.18 d for nepafenac 0.1% and 4.00 d for ketorolac 0.4% (P=.3134). No statistical difference was observed between nepafenac 0.1% and ketorolac 0.4% in mean postoperative pain scores (P>.05). On day 3, the nepafenac 0.1% group had significantly lower mean sensation scores than did the ketorolac 0.4% group for after-drop pain (P=.0090), irritation (P=.0007), and burning/ stinging (P=.0003). Mean overall comfort score was also significantly better for nepafenac 0.1% on day 3 (7.43 vs 6.41; P<.0001). Nepafenac 0.1% and ketorolac 0.4% provide postoperative pain relief after PRK surgery without associated adverse effects on corneal epithelial healing. Nepafenac 0.1% treatment may offer greater comfort upon instillation in patients who have undergone PRK.

Peripheral Keratitis Following Laser in situ Keratomileusis

PURPOSE

To report two different cases of sterile, peripheral keratitis following laser in situ keratomileusis (LASIK).

METHODS

A report of two cases (two eyes of two patients).

RESULTS

In two patients, peripheral infiltrates appeared 1 day after LASIK. One patient had a history of rheumatoid arthritis and both had peripheral corneal changes that may have represented prior inflammatory events. The presentations were quite different, with one occurring in association with an epithelial defect at the edge of the flap and the other occurring without an epithelial defect peripheral to the microkeratome cut. In the second case a similar infiltrate showed up in the unoperated fellow eye. Both patients were treated with aggressive antibiotic and corticosteroid therapy. Both patients recovered well with no loss of best spectacle-corrected visual acuity.

CONCLUSION

Peripheral keratitis can occur in patients following LASIK; preoperative evidence of previous inflammation may be a marker for patients at higher risk. Rheumatoid arthritis patients may be at increased risk for this complication. With careful and aggressive management excellent visual outcomes are still possible.

Frozen cultured sheets of epidermal keratinocytes in reepithelialization and repair of the cornea after photorefractive keratectomy

PURPOSE

To determine whether frozen cultured sheets of human allogeneic epidermal keratinocytes (CEAK) improved wound repair after experimental corneal ablation by photorefractive keratectomy (PRK).

SETTING

Hospital "Luis Sanchez Bulnes" de la Asociación para Evitar la Ceguera en Mexico, I.A.P, and Department of Cell Biology, CINVESTAV-IPN, Mexico City, Mexico.

METHODS

Transepithelial PRK was performed in the right eye of male albino rabbits to obtain a 112 microm deep and 6.0 mm diameter ablation zone. In 17 eyes, the ablations were covered with frozen CEAK; in 11 eyes, the ablations were covered with a disposable contact lens without the cultured sheets; and in the control group (13 eyes), the ablations were not covered. Subepithelial fibrosis and reepithelialization of the ablated zone were evaluated in serial paraffin-embedded tissue sections from all wounds.

RESULTS

Treatment with CEAK reduced fibroblast proliferation and the inflammatory response beneath the ablated zone and produced better organization of the newly formed epithelium by eliminating significant hyperplasia or discontinuities in the periodic acid Shiff-stained basement membrane. It also led to accelerated reepithelialization.

CONCLUSIONS

The use of frozen CEAK as a biologically active wound dressing improved tissue repair at 1 month in corneas ablated by transepithelial PRK in the male albino rabbit model. Treatment with CEAK could improve the outcome of PRK in humans.

Growth factors in corneal wound healing following refractive surgery: A review

The first part of this review article aims to provide important basic definitions of growth factor terminology, and to put forward a model for understanding the role of growth factors in a wound healing context. In the second part of the paper, we review the literature on growth factors in the cornea, including that on changes associated with wound healing following refractive surgery in the epithelial, stromal, and endothelial layers. The role of growth factors in stromal removal, corneal neovascularization, corneal innervation and wound healing is considered. The importance of the epithelial-stromal interaction is discussed, including the role of growth factors in keratocyte apoptosis. In the final section, we review the current literature on endogenous and exogenous modulation of growth factors in corneal wound healing. This includes important in vitro work but aims to emphasize clinically relevant results. Photorefractive keratectomy (PRK) may have short-term complications such as pain and haze, whereas laser in situ keratomilieusis (LASIK) may have longer-term adverse effects on corneal biomechanics. The emerging technique of laser epithelial keratomilieusis (LASEK) provides an interesting alternative wound which may be less susceptible to the inherent complications of PRK and LASIK. At present, the phenomenon of iatrogenic keratectasia following LASIK is not fully understood, but these features of wound healing following PRK may be amenable to growth factor modulation.

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.

The effect of early steroid treatment after PRK on clinical and refractive outcomes

PURPOSE

To evaluate the effects of steroid treatment administered in the first days after excimer laser keratectomy (PRK) on re-epithelialization time, postoperative pain, haze and refractive outcome.

METHODS

A randomised, double masked trial was carried out on two groups of patients (40 patients each), who underwent PRK. Group A (steroid group) received 0.1% fluorometholone acetate whereas group B (NSAID group) received 0.5% ketorolac tromethamine until re-epithelialization was completed. Subsequently, all 80 patients received the same steroid treatment: 0.1%, fluorometholone acetate for myopic corrections up to -5 D, or dexamethasone for myopic corrections exceeding -5 D. Both drugs were tapered off over approximately 3 months. Follow-up examinations were planned at 1, 3, 6, 12 months after surgery.

RESULTS

Re-epithelialization was completed after three days, without any significant difference between groups. A higher hyperopic shift was shown in the steroid group and a more severe regression was reported in the NSAID group (p<0.001). Haze was significantly reduced in the steroid group (p=0.005), especially for myopic corrections over -5 D (p=0.015). Pain was significantly reduced in the NSAID group (p=0.002).

CONCLUSION

Steroid eyedrops administered in the first days after PRK did not affect re-epithelialization time. Moreover, a modulation of the inflammatory response in this period appears to reduce haze and myopic regression in high myopic patients.

Perioperative Microbiologic Profile of the Conjunctiva in Photorefractive Keratectomy

PURPOSE

Therapeutic soft contact lenses are used commonly as an adjunctive treatment after photorefractive keratectomy (PRK) to decrease postoperative pain caused by the movement of lids over the corneal epithelial defect and to facilitate epithelial healing. We assessed the microbiological profile of the conjunctiva of patients undergoing PRK for myopia, before and after the concurrent use of a therapeutic soft contact lens, and compared the effect on ocular bacterial colonization of prophylactic administration of topical tobramycin 0.3% versus ofloxacin 0.3%.

METHODS

Forty-three consecutive eyes from 37 patients underwent PRK for myopia or myopic astigmatism. Eyes were assigned randomly to prophylactic antibacterial treatment with either topical ofloxacin 0.3% or tobramycin 0.3%, applied prior to surgery and three times daily after surgery until therapeutic soft contact lens removal. Material from the conjunctival sac was obtained for bacteriologic cultures prior to surgery. Clinical evaluation of all eyes was conducted prospectively. Three days after PRK, the therapeutic soft contact lenses were removed and cultured. Cultures from the conjunctival sac were then repeated.

RESULTS

No statistically significant differences were observed in culture positivity between the two groups of eyes, in spite of some positive preoperative and postoperative cultures. Only one out of 43 eyes (assigned to the ofloxacin group) developed a peripheral corneal infiltrate. The corneal infiltrate healed completely without sequelae using antibiotic and corticosteroid therapy.

CONCLUSIONS

The use of therapeutic soft contact lenses after PRK with either topical tobramycin 0.3% or ofloxacin 0.3% were well tolerated. However, perioperative positive conjunctival cultures were relatively frequent and prophylactic antibiotics should be used in the setting of an epithelial defect and therapeutic soft contact lens following PRK.

A randomized, comparative open-label study on the efficacy of latanoprost and timolol in steroid induced ocular hypertension after photorefractive keratectomy

PURPOSE

To evaluate the effect of 0.005% latanoprost and 0.50% timolol for the treatment of steroid-induced ocular hypertension (SIOH) after excimer laser photorefractive keratectomy (PRK).

METHODS

In this comparative, open-label study we enrolled 29 patients who received steroid therapy after PRK and developed intraocular pressure (IOP) elevation within 30 days of treatment. Fifteen were randomized to 0.005% latanoprost (group A) and 14 to 0.50% timolol (group B). IOP measurements were scheduled at 1, 3, 7, 15, 30, 60, 90 and 120 days of therapy. RESULTS; We did not find any real differences between latanoprost and timolol except at the 7-day and 15-day timepoints, when latanoprost reduced IOP significantly more than timolol (p=0.033, 0.035, respectively). After 7 days of therapy two of the 14 timolol-treated patients had high IOP (24 and 26 mmHg) but these promptly returned to normal when latanoprost was added. No significant differences were observed in the ocular side effects considered.

CONCLUSIONS

0.005% latanoprost is as safe and effective as 0.50% timolol in the treatment of SIOH after PRK. Both drugs provide a significant and stable IOP reduction in the majority of patients after short-term treatment. These findings are encouraging for the use of latanoprost in the management of SIOH after PRK, although further trials are necessary to consider it as a primary treatment.

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.

Bilateral corneal infiltrates after excimer laser photorefractive keratectomy

A 26-year-old man developed painless inferior subepithelial infiltrates away from the site of ablation in both eyes after excimer laser photorefractive keratectomy (PRK) for myopia. Clinical characteristics of the corneal infiltrates resembled staphylococcal-immune infiltrates. The condition responded to treatment with topical diluted steroids and antibiotics. There was no residual corneal scarring. The infiltrates did not affect the refractive outcome of the surgery. Recognition of this rare entity will help clinicians avoid aggressive investigative and treatment modalities that can affect the results of PRK.

A randomized, comparative study of fluorometholone 0.2% and fluorometholone 0.1% acetate after photorefractive keratectomy

PURPOSE

To compare the efficacy and tolerance of fluorometholone 0.1% acetate and fluorometholone 0.2% eyedrops in the postoperative management of photorefractive keratectomy (PRK).

METHODS

A randomised single-blind comparative study was performed on two groups of 30 patients who underwent myopic PRK. The first group was given fluorometholone 0.1% acetate and the second fluorometholone 0.2%. Uncorrected and best corrected visual acuity, haze, IOP and local tolerance were evaluated. Statistical analysis was done using parametric and non-parametric tests.

RESULTS

Visual acuity did not differ in the two groups; both were homogeneous as far as refractive error and haze were concerned. Three patients (10%) treated with fluorometholone 0.2% and two patients (6.6%) with fluorometholone 0.1% acetate developed ocular hypertension, but this was not statistically significant.

CONCLUSIONS

Fluorometholone 0.1% acetate was effective on inflammation after PRK, with the same efficacy as fluorometholone 0.2%.

Toxicity of topical anesthetic agents to human keratocytes in vivo

PURPOSE

To test the potential toxicity on human keratocytes of topical anesthetic agents used after photorefractive keratectomy (PRK) to reduce or eliminate pain.

SETTING

Department of Ophthalmology, Doheny Eye Institute, University of Southern California, Los Angeles, California, USA.

METHODS

Cultured human keratocytes were incubated with commercially available tetracaine and proparacaine at reduced concentrations of 0.001%, 0.01%, 0.1%, and 0.25%. Evaluations were performed by phase-contrast microscopy and tetrazolium salt colorimetric assay every 2 hours for 12 hours after adding 1 of the anesthetic agents to the media.

RESULTS

After time of incubation and concentration were adjusted, both drugs reduced overall cell viability; however, tetracaine produced a larger decrease in cell viability than proparacaine (P = .008). For both drugs, significant differences were found among concentrations for and across time (P < .001 and P = .004, respectively).

CONCLUSION

Both tetracaine and proparacaine had toxic effects on stromal keratocytes related not only to drug concentrations but also to time exposure. These findings underscore the widespread concern that anesthetic drugs may affect corneal stromal wound healing after PRK.

Permanent glaucomatous visual loss after photorefractive keratectomy

A 41-year-old man who had photorefractive keratectomy (PRK) for myopia developed corneal haze. After intensive treatment with topical corticosteroids, he developed elevated intraocular pressure and optic nerve damage. Because of an inadequate response to steroid discontinuation and medical treatment, the patient required a glaucoma filtering procedure. Corticosteroid-induced glaucoma is a possible complication of the treatment often associated with PRK. Careful patient screening and disclosure of this risk are imperative.