Karin Szerenyi

Clinical Follow-up of Phototherapeutic Keratectomy for Treatment of Corneal Opacities

We performed phototherapeutic keratectomy with a 193-nm excimer laser on 18 sighted patients (18 eyes) to treat corneal opacities. The corneal opacities were caused by corneal dystrophies in five patients; corneal scars secondary to corneal ulcers in six patients; corneal scar secondary to trauma in four patients; and band keratopathy, atopy, or corneal calcification in three patients. Mean follow-up was eight months (range, two to 18 months). Corneal clarity improved in 14 of the 18 eyes (77.7%). Four patients, three with band keratopathy or calcification and one with postinfectious corneal scar, did not improve. Uncorrected visual acuity improved in 11 patients, did not improve in five patients (including the four patients in whom treatment failed), and decreased in another two patients, apparently because of an increase in irregular astigmatism. A hyperopic shift was observed in ten patients. None of the successfully treated eyes developed surface problems or recurrence of the disease during the follow-up. Phototherapeutic keratectomy thus appears to be a safe and effective alternative to penetrating keratoplasty in some patients with selected anterior stromal opacities.

Decrease in normal human corneal sensitivity with topical diclofenac sodium.

We tested the effect of topical diclofenac sodium on corneal sensitivity in the human eye. Corneal sensitivity was measured in ten adult subjects with the Cochet-Bonnet esthesiometer before, and immediately after, applying one drop of diclofenac sodium 0.1% in one eye and one drop of diclofenac vehicle in the other eye. Application was repeated every five minutes for 20 minutes; then no more drops were applied, and corneal sensitivity was measured every 15 minutes until sensitivity measurements returned to baseline levels. Diclofenac sodium decreased corneal sensitivity significantly (P = .0001) in all ten subjects, compared with eyes treated with the vehicle. The effect of diclofenac sodium increased as additional drops were administered. After the drug instillation was stopped, corneal sensitivity returned to baseline measurements within less than an hour in all the subjects. Diclofenac sodium substantially lowers sensitivity in normal, unoperated-on human corneas; the vehicle has no measurable effect on sensitivity.

Effect of diclofenac on corneal haze after photorefractive keratectomy in rabbits

PURPOSE To evaluate the ability of topical diclofenac to decrease corneal opacity after excimer laser photorefractive keratectomy (PRK). METHODS Twenty New Zealand white rabbits underwent a unilateral 193-nm excimer laser myopic photorefractive keratectomy to correct 5 diopters. There were four groups of five rabbits each. The first group of rabbits received postoperative topical treatment with placebo (Voltaren Ophthalmic vehicle), the second group received topical 0.1% diclofenac, the third group received topical corticosteroid (0.1% fluorometholone), and the fourth group received diclofenac and fluorometholone. In the first month, the topical drugs were applied four times daily, and in the second month twice daily. Corneal haze was graded from 0 (totally clear) to 4 (completely opaque cornea). Slit-lamp pictures were obtained at weeks 2, 4, and 8, and keratometry readings was performed at weeks 4 and 8. At week 8, the rabbits were killed, and the eyes were submitted for histologic examination. RESULTS At week 8, there was less corneal haze in the diclofenac-treated animals and in the fluorometholone-treated animals than in the control group, but only in the diclofenac-treated group was the difference statistically significant. Combination treatment with diclofenac and fluorometholone did not result in a further decrease in haze. CONCLUSIONS These data suggest that diclofenac and fluorometholone may influence corneal wound healing in rabbits after excimer laser PRK and support a potential role for using topical nonsteroidal anti-inflammatory drugs in preventing the development of excessive corneal haze after excimer laser surgery.

Immunochemistry with 5-bromo-2-deoxyuridine for visualization of mitotic cells in the corneal epithelium

The purpose of this study was to determine whether the DNA of mitotic cells in the corneal and conjunctival epithelium can be labeled with 5-bromo-2-deoxyuridine (BrdU) immunostaining. Both corneas of four New Zealand white rabbits were deepithelialized in the center and the regenerated epithelium was evaluated for mitosis at 1, 3, 6, and 10 days. Unwounded corneas of three rabbits were labeled for baseline measurements. We administered the marker intravenously to all seven rabbits 15 h before scheduled killing. Immediately after killing, all of the globes were enucleated and histologic sections were prepared. In unwounded corneas, labeled cells were quantitated and the fraction of mitotic cells in the center of the cornea, in the periphery of the cornea, and in the conjunctiva were compared. In deepithelialized corneas, increase in mitosis in the central epithelium was quantitated. All of the unwounded eyes showed mitosis in the basal layer of both the corneal and conjunctival epithelium. In the center of the cornea 4.1 ± 2.9% of the epithelial cells were labeled, in the corneal periphery 4.3 ± 1.7% of the cells were labeled, and in the conjunctiva 4.1 ± 1.9% of the epithelial cells were labeled, with a p value ranging from 0.84 to 0.99. In wounded corneas, when compared with cell counts in unwounded eyes, 52.6% of the epithelial cells were in mitosis on day 3, 13.9% were in mitosis on day 6, and by day 10 baseline values of 4.2% were obtained. We conclude that BrdU immunostaining is a safe, efficient, and less costly alternative to autoradiography for visualization of dividing corneal and conjunctival epithelium.

Prostaglandin E2 production after lamellar keratectomy and photorefractive keratectomy

PURPOSE To compare the levels of prostaglandin E2 (PGE2) in corneal tissue after 193-nanometer excimer laser keratectomy and mechanical keratectomy with a microkeratome. METHODS Four rabbits underwent 193-nanometer excimer laser phototherapeutic keratectomy on one eye, and lamellar keratectomy with the microkeratome on the fellow eye. The corneas were harvested at 10 hours after the treatment and quantitated for PGE2 levels using an enzyme-linked immune assay. Control levels of PGE2 in untreated corneas were obtained from a previous study. RESULTS Unoperated control corneas had low levels of PGE2 (1.79 +/- 1.0 pg/mL). Both surgical techniques resulted in a significant (p < .01) increase in PGE2. Corneas ablated mechanically with the microkeratome had an average PGE2 level of 15.48 +/-5.36 pg/mL, which represented an 8.6-fold increase compared to control; there was an additional 330% mean increase in PGE2 concentration in the laser-ablated corneas (51.29 +/- 36.08 pg/mL) compared to the corneas treated with mechanical lamellar keratectomy (p = .014). CONCLUSIONS Mechanical and photochemical superficial keratectomies induce production of an inflammatory mediator, PGE2. The 193-nanometer excimer laser irradiation causes a greater increase of PGE2 production in the corneal tissue than does keratectomy with the microkeratome; this observation may support a role for cyclo-oxygenase inhibitors in postoperative therapy.

Keratitis as a complication of bilateral, simultaneous radial keratotomy.

During a one-month period, we examined four patients referred for evaluation of probable microbial keratitis after bilateral, simultaneous radial keratotomy. Each patient had midstromal infiltrates compatible with microbial keratitis that involved one or more of the radial incisions. In two patients the keratitis was bilateral. All patients had been treated empirically with antibiotic agents; superficial cultures with cotton-tipped applicators and corneal scraping by inserting a platinum spatula into the radial incisions were negative. Corneal biopsy of one patient disclosed gram-positive rods and culture of the biopsy specimen grew diphtheroids. The infiltrates gradually resolved over a period of several months with intensive antibiotic therapy. Sight-threatening infectious keratitis can occur after radial keratotomy, and we believe that simultaneous bilateral ocular surgery of any kind should be discouraged.

Topical diclofenac treatment prior to excimer laser photorefractive keratectomy in rabbits.

PURPOSE This study sought to determine whether pre- and posttreatment with topical diclofenac sodium 0.1% eye drops suppresses corneal inflammation after 193-nanometer excimer laser corneal ablation more effectively than does posttreatment alone. METHODS Eight rabbits were divided into four groups. Animals in group I were treated with topical diclofenac every half hour for 2 hours prior to photorefractive keratectomy; treatment was continued every hour for 3 hours after the ablation. Group II animals, used as controls, were treated with the diclofenac vehicle according to the same schedule. The third group (III) received diclofenac topically only after the excimer laser ablation. The fourth group (IV) consisted of normal corneas from these same animals. At 3 hours after ablation, prostaglandin E2 (PGE2) levels were measured in the corneas and leukocytes were quantified. RESULTS Treatment with topical diclofenac significantly reduced levels of PGE2 compared to treatment with the vehicle (p = .024). Presurgical treatment with topical diclofenac did not result in greater suppression of PGE2 than did posttreatment alone (5.72 +/- 0.91 pg/mL versus 5.79 +/- 1.29 pg/mL). Similarly, there was a significant inhibition of leukocyte invasion in the diclofenac treated corneas (I vs II: p = .019, III vs II: p = .024), but no statistically significant difference between pretreatment and posttreatment alone groups (I vs III: p = .72). CONCLUSIONS Topical administration of diclofenac reduces the release of PGE2 and the migration of polymorphonuclear leukocytes in the rabbit cornea 3 hours after 193-nanometer excimer laser ablation. However, pretreatment of the cornea, starting 2 hours prior to laser surgery, does not seem to offer advantages over postablation treatment in this animal model.