- Email: [email protected]
Phototherapeutic keratectomy in children: 5-year results
Phototherapeutic keratectomy in children: 5-year results Rudolf Autrata, MD, PhD, Jaroslav Rehurek, MD, PhD, Kristina Vodicˇkova´, MD Purpose: To evaluate the efficacy and safety of phototherapeutic keratectomy (PTK) for the treatment of superficial corneal opacities, surface irregularities, epithelial instability, and reepithelialization failure in pediatric patients and study the visual and refractive changes after combined PTK and photorefractive keratectomy (PRK). Setting: Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic. Methods: This retrospective clinical study comprised children who had PTK or PTK combined witih PRK from September 1996 to January 2000. The goals of treatment were to improve visual acuity and reduce or eliminate subjective ocular discomfort (eg, pain, lacrimation, and photophobia). A Nidek EC-5000 excimer laser was used in PTK mode with a 3.0 to 6.0 mm optical zone and a 4.0 to 7.5 mm transition zone. Results: Forty-one pediatric patients (41 eyes) were included. Twenty-three eyes had PTK only, and 18 eyes had PTK combined with PRK to reduce preoperative myopia (11 eyes) or hyperopia (7 eyes). The mean patient age was 11.4 years (range 8 to 18 years) and the mean follow-up, 4.8 years (range 3 to 6 years). The best spectacle-corrected visual acuity (BSCVA) improved in all patients, and episodes of ocular pain or discomfort, lacrimation, and photophobia diminished. The mean preoperative BSCVA of 6/38 (range 6/10 to 1/60) improved to 6/12 (range 6/6 to 6/38) at the last postoperative examination. Eight eyes gained 5 or more Snellen lines of BSCVA; 11 gained 4 lines, 9 gained 3 lines, 7 gained 2 lines, 5 gained 1 line, and 1 eye was unchanged. No eye lost a line of BSCVA. The mean preoperative spherical equivalent (SE) decreased from ⫺5.32 to ⫺1.16 diopters (D) in the 11 myopic eyes and from ⫹4.72 to ⫹1.51 D in the 7 hyperopic eyes within 3 years of the combined procedure. Conclusions: Phototerapeutic keratectomy is an effective and safe procedure for the treatment of various surface corneal disorders in children. It can improve best corrected visual acuity and eliminate ocular pain and irritation. Preoperative myopia and hyperopia were effectively reduced by a combination of PTK and PRK. J Cataract Refract Surg 2004; 30:1909–1916 2004 ASCRS and ESCRS
T
he use of excimer lasers in ophthalmic surgery was first described by Trokel and coauthors in 1983.1 Serdarevic and coauthors2 proposed the first therapeutic use of the excimer laser to treat experimental Candida infectious keratitis in 1985. The first phototherapeutic
Accepted for publication January 20, 2004. Reprint requests to Rudolf Autrata, MD, PhD, Department of Ophthalmology, Masaryk University Hospital, Cernopolni 9, Brno 61300, Czech Republic. E-mail: [email protected]. 2004 ASCRS and ESCRS Published by Elsevier Inc.
keratectomy (PTK) procedure in a sighted eye was performed by Gartry and coauthors3 in 1988. Experimental and clinical research on the successful removal of superficial corneal opacities with the attainment of smooth regular corneal surfaces and visual acuity improvement has prompted extensive use of PTK with excimer lasers.1–9 The current clinical practice of excimer laser PTK has expanded to treat a range of corneal disorders. Generally, excimer laser PTK is used to remove superficial corneal stromal opacities (eg, postinfectious traumatic 0886-3350/04/$–see front matter doi:10.1016/j.jcrs.2004.02.047
PHOTOTHERAPEUTIC KERATECTOMY IN CHILDREN
scarring and anterior stromal dystrophies), treat or smooth irregular surface disorders, treat epithelial instability and reepithelialization failure (eg, in recurrent corneal erosion syndrome and vernal keratoconjunctivitis), and reduce iatrogenically produced refractive errors including induced irregular astigmatism after cataract surgery, penetrating keratoplasty (PKP), and other procedures. The diagnostic indication for PTK can fall into several categories; eg, rough band keratopathy, which may present with visual symptoms and ocular pain. In patients with good visual potential, particular care must be taken to avoid excessive refractive changes and irregular astigmatism. Clinical studies of the use of PTK in pediatric patients are limited to a few reports of a few sample cases. In this study, we examined the clinical features and visual and refractive changes in children with superficial corneal opacities after PTK performed with the Nidek EC-5000 excimer laser system. We evaluated the efficacy and safety of PTK for the treatment of superficial corneal opacities, surface irregularities, and epithelial instability. To our knowledge, this is the first study of PTK in a relatively large group of children with a long-term follow-up.
Patients and Methods The retrospective study comprised consecutive pediatric patients who had excimer laser PTK at Masaryk University Hospital Eye Clinic from September 1996 to January 2000. Indications for PTK included recurrent corneal epithelial erosions, superficial scars or a persistent epithelial defect after keratitis, lagophthalmos, dry spots and mucous plaques in vernal keratoconjunctivitis, band keratopathy, anterior corneal dystrophies, corneal scars secondary to postinfectious keratitis, and previous trauma. The main treatment goals were to improve visual acuity and reduce or eliminate subjective ocular discomfort; ie, pain, lacrimation, and photophobia. All parents were given a detailed explanation of the procedure and the risks/benefits of the laser treatment. They signed a consent form detailing their understanding of PTK or PTK combined with photorefractive keratectomy (PRK) for their child. The research was approved by the Masaryk University Children Hospital‘s institutional review board/ ethics committee. Approval of the ethics committee for PTK in children was obtained before the surgical procedures. All patients had routine ophthalmic examinations that included uncorrected visual acuity and best spectacle-corrected visual acuity (BSCVA), manifest and cycloplegic 1910
(cyclopentolate) refractions (Nidek ARK800), biomicroscopy, videokeratoscopy (C-scan, Technomed), pachymetry (Nidek UP1000), tonometry (Goldmann tonometry and Tono-Pen威 [Medtronic Solan]), Schirmer test, and fundoscopy by indirect binocular ophthalmoscopy. After treatment, the patients were examined daily for the first postoperative week; at 1, 3, 6, 9, and 12 months; and then after 6 months. All examinations and laser procedures were performed by the same ophthalmologist (R.A.). The PTK procedure was performed under topical anesthesia with oxybuprocaine hydrochloride 0.5%; no general pharmacologic pretreatment was administered. The Nidek EC-5000 excimer laser was calibrated before each treatment by ablating a poly(methyl methacrylate) card to ⫺3.0 diopters (D). The treatment zone was 6.0 to 7.5 mm, and the transition zone of 1.0 mm was set beyond the ablation zone in all procedures. The ablation depth was 18 to 120 m, and the pulse frequency was 30 Hz. Hydroxypropyl methylcellulose 1% solution was used as the masking agent as needed during the procedure to achieve a smoother ablation. In 2 eyes with smooth band keratopathy, the epithelium was used as a smoothing template for the transepithelial laser ablation. However, in 3 cases of rough band keratopathy, large calcified plaques were removed using mechanical debridement before laser ablation. In the combined procedure, PRK was performed immediately after PTK. The amount of PRK was generally set at the pretreatment refraction. The maximum spherical diopters of hyperopic laser correction was based on preoperative measurements, but only 30% to 50% of diopters of preoperative myopia was set because post-PTK treatment hyperopic shift usually occurs and correlates with stromal ablation depth. The decision to reduce the myopic correction in combined cases by 30% to 50% was based on our experience with 128 PTK procedures in adult patients. In these patients, at 3 years, the mean final hyperopic shift was ⫹1.73 D ⫾ 1.46 (SD) for the 6.5 mm optical zone and the mean central ablation depth was 61.34 ⫾ 23.51 m. Subsequently, every 10 m of PTK ablation depth caused a mean 0.282 D hyperopic shift. This calculation was used for setting parameters in the combined pediatric cases. An additional consideration was the refraction in the second eye of each patient because our goal was postoperative myopic isometropia. In myopic PRK, the largest optical zone of 6.5 mm (transition zone 7.5 mm) was used and in hyperopic PRK, the 5.5 mm optical zone (transition zone 9.0 mm). The cornea was cooled before and after ablation with 10oC sterile balanced salt solution (BSS威). At the end of the procedure, a drop of tobramycin (Tobrex威) and a drop of diclofenac (Naclof威) were administered and a therapeutic contact lens (Acuvue威, base curve 9.1 mm, Vistakon) was applied to the eye. The therapeutic contact lens remained in situ for 3 to 4 days postoperatively. The patients were seen daily in our department as hospital inpatients until the epithelial defect healed. Tobrex was instilled 5 times daily for the first postop-
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erative week, and fluorometholone 0.1% (Flucon威) ophthalmic drops were administered 5 times daily for 1 month and then tapered over 6 months. The Student t test, Mann-Whitney test (analysis of nonparametric values), and Fisher exact test (analysis of categorized data) were used for statistical analysis. Ninety-five percent confidence interval limits were calculated for differences in mean results. Continuous variables were described with mean, standard deviation, and minimum and maxium values. A P value of less than 0.05 was considered statistically significant. Statistical analysis was performed with the cooperation of the Institute of Medical Statistics at Masararyk University, Brno.
Results Forty-one consecutive pediatric patients (41 eyes) were included. Twenty-three eyes had PTK only; 18 eyes were treated with combined PTK and PRK to reduce preoperative myopia (11 eyes) or hyperopia (7 eyes). The mean age of the patients was 11.4 ⫾ 4.65 years (range 8 to 18 years). The mean follow-up was 4.8 ⫾ 1.9 years (range 3 to 6 years). Clinical Features Superficial corneal opacities were successfully removed from the ablation zone and the corneal visual
axis in all patients. Nine eyes with recurrent corneal erosion syndrome preoperatively had no recurrences during follow-up. Ocular pain or discomfort, lacrimation, and photophobia that patients reported preoperatively were not reported after PTK. Complete and uneventful corneal reepithelialization occurred in all eyes within 5 days of the procedures. The mean reepithelialization time in the PTK-only group and the group with combined PTK and myopic PRK (6.5 mm ablation zone, 7.5 mm transition zone) was 2.5 ⫾ 0.7 days; in the group with combined PTK and hyperopic PRK (9.0 mm ablation zone), it was 3.85 ⫾ 1.25 days. The difference was statistically significant (P⬍.05). Visual Outcome The mean BSCVA in all eyes was 0.21 ⫾ 0.23 (range 0.63 to 0.016) preoperatively and 0.57 ⫾ 0.34 (range 1.0 to 0.1) at the last examination. The difference was statistically significant (P ⫽ .0246). Visual acuity before and after PTK (or PTK combined with PRK) in each diagnostic group of corneal disorders is shown in Table 1. The gain in Snellen lines of BSCVA at the last examination is shown in Figure 1. Twenty-eight eyes
Table 1. The BSCVA preoperatively and at the last examination (3 to 6 months) after PTK or PTK combined with PRK. Number of Eyes (%)
Mean Preop BSCVA (Range)
Mean Postop BSCVA (Range)
Recurrent corneal erosion syndrome
9 (22.0)
6/24 (6/12 to 6/38)
6/10 (6/6 to 6/15)
Persistent epithelial defect
7 (17.0)
6/38 (6/15 to 3/60)
6/15 (6/7.5 to 6/30)
Dry spot or mucous plaque (atopic or vernal keratoconjunctivities)
5 (12.2)
6/20 (6/12 to 4/60)
6/10 (6/5 to 6/20)
Band keratopathy
5 (12.2)
6/60 (6/38 to 1/60)
6/15 (6/10 to 6/48)
Cogan’s
1 (2.4)
6/30
6/10
Messmann’s
1 (2.4)
6/24
6/6
Reis-Ruckler’s
5 (12.2)
6/60 6/30 to 3/60
6/12 6/10 to 6/20
Posttraumatic superficial corneal scar
2 (4.8)
6/38 and 6/60
6/12 and 6/15
Postherpetic entral superficial scar
4 (9.6)
6/60 (6/38 to 3/60)
6/15 (6/12 to 6/24)
Recurrent posttraumatic pseudopterygium
2 (4.8)
6/12 and 6/10
6/7.5 and 6/10
41 (100)
6/30 (6/10 to 1/60)
6/10 (6/5 to 6/48)
Diagnosis
Corneal dystrophy
Total BSCVA ⫽ best spectacle-corrected visual acuity
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Figure 1. (Autrata) Change in BSCVA at the last examination (3
Figure 2. (Autrata) Hyperopic shift post PTK shown over time.
to 6 years after PTK or combined PTK and PRK) expressed as a gain of Snellen lines (n ⫽ 41).
Induced hyperopia peaked in the first 2 months, decreased over time, and stabilized at 12 months (n ⫽ 23).
(68.3%) gained 3 or more lines, 7 eyes (17.0%) gained 2 lines, and 5 eyes (12.2%) gained 1 line. No eye lost a line of BSCVA.
In the 11 myopic eyes, the mean spherical equivalent (SE) refraction was ⫺5.32 ⫾ 2.21 D (range ⫺2.50 to ⫺7.75 D) preoperatively and ⫺1.16 ⫾ 1.54 D (range ⫹1.25 to ⫺3.75 D) 2 years after combined PTK and myopic PRK (Figure 3). In the 7 hyperopic eyes, the mean SE refraction was ⫹4.72 ⫾ 2.58 D (range ⫹2.25 to ⫹6.50 D) preoperatively and ⫹1.52 ⫾ 1.77 D (range ⫹0.75 to ⫹3.75 D) 2 years after combined PTK and hyperopic PRK (Figure 4). The postoperative reduction in the mean SE refraction in the myopic and hyperopic eyes (n ⫽ 18) was statistically significant (P⬍.05).
Refractive Changes In the 23 PTK-only eyes, the mean hyperopic shift was 2.14 ⫾ 1.17 D (range ⫹0.25 to ⫹3.50 D) at 2 years and 2.23 ⫾ 1.29 D (range ⫹0.50 to ⫹3.75 D) at 1 year. The difference was not statistically significant. The induced hyperopia peaked at the first month (mean 3.76 ⫾ 1.84 D) and tended to decrease after that, with stabilization at 12 months (Figure 2). At 3 years, the mean refractive change was ⫹2.09 ⫾ 1.21 D and the mean central ablation depth was 52.41 ⫾ 31.56 m. An ablation depth of 10 m resulted in 0.39 D of the mean hyperopic shift at the final examination. The mean central keratometry was 42.15 ⫾ 1.47 D before PTK, 38.96 ⫾ 1.75 D at 6 months (P⬍.05), and 39.41 ⫾ 1.67 D at 12 months. The difference between 6 and 12 months was not statistically significant.
Complications No visually disabling complications related to PTK and PRK were observed. Nine eyes (21.9%) developed grade I or II subepithelial haze at 1 to 3 months. The haze disappeared gradually within 12 to 18 months and did not affect the BSCVA. No eye developed adverse reactions to topical steroids (eg, an intraocular pressure increase).
Figure 3. (Autrata) Change in the mean SE refraction 2 years after
Figure 4. (Autrata) Change in the mean SE refraction 2 years after
PTK combined with myopic PRK (n ⫽ 11).
PTK combined with hyperopic PRK (n ⫽ 7).
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There were no postoperative complications such as infection, epithelial healing problems, corneal melt, or recurrences after PTK for corneal erosion syndrome. The PTK was well tolerated by all children, who reported mild pain or discomfort at days 1 to 3.
Discussion Phototherapeutic keratectomy has been performed and evaluated for at least 10 years in adult patients and has proved successful. The encouraging anatomic and visual results in studies of PTK for superficial corneal opacities and irregularities in the adult population have led to widespread approval of the procedure among ophthalmologists and patients.10–14 The 193 nm excimer laser has been used to treat recurrent corneal erosion syndrome and anterior stromal and superficial scarring from postinfectious and posttraumatic causes, including inactive herpes simplex virus keratitis, anterior corneal dystrophies, and band keratopathy.8,13,15–17 Most clinical studies report the results of PTK in adult patients. We evaluated the clinical features and visual and refractive changes in children with superficial corneal disorders after PTK or PTK combined with PRK performed with the Nidek EC-5000 excimer laser and followed for more than 2 years. Many authors report induced refractive changes, mainly a hyperopic shift, as a complication of treatment.3,18–21 With Bowman’s layer ablated, the hyperopic shift increases with the depth of treatment. In our study, we found a mean hyperopic shift of ⫹2.14 D 2 years after PTK (without additional PRK) in 23 pediatric eyes with various superficial corneal disorders. In all patients, we used a 5.0 to 6.5 mm ablation zone with a 7.5 mm transition zone, an ablation depth of 18 to 120 m, and a masking agent. Dogru and coauthors22 conclude that a shallow ablation depth (less than 100 m), the presence of a transition zone setting, and the use of a masking substance significantly reduce the hyperopic shift. The use of fluid-shielding agents is not routine in every PTK procedure, eg, in the treatment of recurrent epithelial erosions, and masking the surface of Bowman’s layer is rarely required. Although the ablation depth depends on individual corneal pathology, we believed an ablation depth of less than 100 m was sufficient to successfully treat all corneal opacities and surface corneal disorders in our series. A correlation
between ablation depth, ablation zone diameter, transition zone, and hyperopic shift has been detected.23 Hyperopic shift can be minimized by adding hyperopic treatment to the plano treatment. However, shifts in refraction after PTK are unpredictable in degree and direction, possibly because of underlying pathology. In our study, with a follow-up of 3 to 6 years after PTK and combined PTK and PRK, the mean SE refraction was stabilized at 12 months. Recurrent erosions represent an early indication for PTK treatment. No studies of PTK for recurrent erosions in pediatric cases have been published. In cases of recurrent corneal erosion syndrome, PTK has been reserved for patients in whom conventional medical treatments, including topical lubricants and hyperosmotic solutions, mechanical debridement, and soft contact lenses, have failed. A large, single, central ablation zone (5.0 to 6.5 mm) is recommended for paracentral or axial epithelial abnormalities to avoid possible irregular astigmatism. Most patients are symptom free within the first few days of treatment and have no recurrences.14,17,24 In our pediatric group of 9 eyes with recurrent erosions, no eye had a recurrence during follow-up. The mechanism by which excimer laser ablation prevents recurrent corneal erosion may lie in the strong bonds formed between the epithelial basement membrane and Bowman’s layer or the stromal bed postoperatively. The presence of persistent corneal haze after PTK for recurrent erosions is rare due to the shallow ablation depth. Most investigators4,14,16,25 report no adverse effects on visual acuity after PTK for recurrent epithelial erosions in adult patients. This was the same in our pediatric patients. In band keratopathy, there is extracellular deposition of granular material in the epithelial basement membrane, Bowman’s layer, and anterior stroma. The material usually consists of calcium phosphate and carbonate salts. Single axial ablation zones restricted to the anterior 100 m of the stroma result in visual acuity improvement with a reduction in complications including irregular astigmatism and hyperopic shift.13,19 No studies of PTK for band keratopathy in children have been published. In our group of children, 5 eyes had band keratopathy; their mean BSCVA improved from 6/60 (range 6/38 to 1/60) preoperatively to 6/15 (range 6/9 to 6/48) 3 to 6 years after PTK. The corneal clarity in all eyes remained improved, with no recurrence of
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Figure 5. (Autrata) The cornea of a 12-year-old boy with Reis-
Figure 6. (Autrata) The cornea in Figure 5, 3 years after PTK
Buckler’s dystrophy and painful recurrent corneal erosion syndrome. The BSCVA was 6/60 with an SE refraction of ⫹6.25 D.
(50 m ablation depth) combined with hyperopic PRK of ⫹6.50 D. The BSCVA was 6/12 with an SE refraction of ⫹2.75 D. There were no postoperative recurrences of epithelial erosions.
band keratopathy in the treated zone. Phototherapeutic keratectomy appears to be a successful treatment option for smooth band keratopathy to relieve the associated pain and improve corneal clarity and therefore visual acuity in potentially sighted eyes. The combined treatment using manual scraping, ethylenediaminetetraacetic acid, and excimer laser ablation is better suited to cases with coarse irregular changes with flakes of calcification. The objectives of excimer PTK for the treatment of corneal dystrophies overlap those for other corneal pathologies: Painful recurrent corneal erosions may be prominent in Cogan’s and Reis-Buckler’s dystrophies, whereas reduced vision secondary to the subepithelial opacities of Reis-Buckler’s dystrophy and loss of anterior stromal clarity in granular and lattice dystrophies provide optical indications for treatment. Fagerholm et al.18 report 27 patients with corneal dystrophy. Twentyone (77.8%) achieved a long-term therapeutic goal of improved visual acuity. Tuunanen and Tervo26 report improved BSCVA in 4 of 5 cases of corneal dystrophy. Ablation of the epithelium overlying irregular anterior stromal opacities in certain cases of corneal dystrophy may be beneficial.20,27 In our pediatric group of 7 eyes with corneal dystrophy, the BSCVA improved in all cases (Table 1). Two eyes with Reis-Buckler’s dystrophy received combined PTK and hyperopic PRK. In the first eye, the preoperative SE refraction of ⫹6.25 D improved and stabilized at ⫹2.75 D and the BSCVA of 6/60 improved to 6/12 at 36 months (Figures 5 and 6). In the second eye, the preoperative refraction (SE)
of ⫹4.25 D decreased to ⫹1.50 D and the BSCVA of 6/60 improved to 6/9. In conditions in which the corneal opacities are anteriorly placed, PTK appears to be a promising alternative to lamellar keratoplasty or PKP. Phototherapeutic keratectomy has been used to treat anterior stromal corneal scars secondary to various etiologies including postinfectious keratitis and after trauma. Masking agents are used during the procedure, and slitlamp biomicroscopy is performed frequently to gauge treatment progress. Phototherapeutic keratectomy has also been effective in the treatment of postherpes simplex corneal scarring. Fagerholm et al.18 report 15 such patients, including 2 children treated under general anesthesia, with a mean follow-up of 15.7 months. Eighty percent of the eyes achieved 3 or more Snellen lines of improved visual acuity. Campos et al.20 used prophylactic systemic acyclovir in a patient with a postherpetic scar and lattice dystrophy. No recurrence of herpetic keratitis occurred during the 15-month follow-up. Talamo and coauthors28 pretreated a patient with trifluorothymidine daily for several days before PTK for a herpes simplex scar that had shown no clinical signs of active keratitis for more than 1 year. In our study, PTK was performed for a postherpetic central scar in 4 eyes. The children were treated with oral acyclovir for 2 days before PTK and for 10 days after the procedure. All 4 eyes gained 3 or more Snellen lines of BSCVA, and no reactivation of the keratitis was recorded during more than 3 years of follow-up.
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Two of the eyes had combined PTK and PRK with successful visual and refractive outcomes. Relatively small numbers of posttraumatic scars treated by PTK have been reported.4,18,20,26 In our series, 2 children with a central posttraumatic scar gained more than 3 Snellen lines of visual acuity; the improvement remained throughout the follow-up. In some circumstances, combined PTK and PRK is appropriate. The PTK and PRK may be indicated for an associated corneal opacity or persistent epithelial defects with preoperative myopia, hyperopia, and astigmatism. Combined PTK and PRK has been performed for recurrent dystrophies after PKP21,29 and to treat irregular astigmatism. Gibralter and Trokel30 describe a method of incorporating combined PTK and PRK. Lawless and coauthors31 report 14 eyes that required a dual PTK and PRK treatment for manifest scarring and regression unresponsive to topical corticosteroids after an initial myopic PRK. A 5.0 mm transepithelial PTK ablation zone was used, and then PRK was performed. During a follow-up of 1 to 9 months, no scarring redeveloped and no significant refractive regression occurred. The eyes appeared to stabilize more rapidly than after the primary PRK. These promising results suggest a future role for PTK combined with PRK in the management of challenging problems of surface or anterior stromal corneal pathology and a refractive error and iatrogenically induced refractive astigmatism. In PRK, no generalized surgical plan can be used to treat various corneal disorders that have yielded or may yield to the precision of excimer laser PTK. Thus, it remains the responsibility of the ophthalmic surgeon to carefully choose and counsel patients suitable for PTK treatment and to tailor the subsequent PTK strategy on an individual basis. Based on our study results, PTK seems to be an effective and safe procedure in children to treat various surface corneal disorders. Phototherapeutic keratectomy can improve the best corrected visual acuity and eliminate ocular pain and irritation as symptoms of these ocular surface pathologies. In our study, combined PTK and PRK procedures resulted in effective reduction of the preoperative refractive errors.
References 1. Trokel SL, Srinivasan R, Braren B. Excimer laser surgery of the cornea. Am J Ophthalmol 1983; 96:710–715
2. Serdarevic O, Darrell RW, Krueger RR, Trokel SL. Excimer laser therapy for experimental Candida keratitis. Am J Ophthalmol 1985; 99:534–538 3. Gartry D, Kerr Muir M, Marshall J. Excimer laser treatment of corneal surface pathology: a laboratory and clinical study. Br J Ophthalmol 1991; 75:258–269 4. Fo¨rster W, Grewe S, Atzler U, et al. Phototherapeutic keratectomy in corneal diseases. Refract Corneal Surg 1993; 9(suppl):S85–S90 ¨ rndahl M, Fagerholm P, Fitzsimmons T, Tengroth B. 5. O Treatment of corneal dystrophies with excimer laser. Acta Ophthalmol 1994; 72:235–240 6. Kozobolis VP, Siganos DS, Meladakis GS, Pallikaris IG. Excimer laser phototherapeutic keratectomy for corneal opacities and recurrent erosion. J Refract Surg 1996; 12: S288–S290 7. Hahn TW, Sah WJ, Kim JH. Phototherapeutic keratectomy in nine eyes with superficial corneal diseases. Refract Corneal Surg 1993; 9(suppl):S115–S118 8. Nassaralla BA, Garbus J, McDonnell PJ. Phototherapeutic keratectomy for granular and lattice corneal dystrophies at 1.5 to 4 years. J Refract Surg 1996; 12:795–800 9. Thompson V, Durrie DS, Cavanaugh TB. Philosophy and technique for excimer laser phototherapeutic keratectomy. Refract Corneal Surg 1993; 9(suppl):S81–S85 10. Lohmann CP, Sachs H, Marshall J, Gabel V-P. Excimer laser phototherapeutic keratectomy for recurrent erosions: a clinical study. Ophthalmic Surg Lasers 1996; 27: 768–771 11. Thompson VM. Excimer laser phototherapeutic keratectomy: clinical and surgical aspects. Ophthalmic Surg Lasers 1995; 26:461–472 12. Hersh PS, Burnstein Y, Carr J, et al. Excimer laser phototherapeutic keratectomy; surgical strategies and clinical outcomes. Ophthalmology 1996; 103:1210–1222 13. O‘Brart DPS, Gartry DS, Lohmann CP, et al. Treatment of band keratopathy by excimer laser phototherapeutic keratectomy: surgical techniques and long term follow up. Br J Ophthalmol 1993; 77:702–708 14. O‘Brart DPS, Kerr Muir MG, Marshall J. Phototherapeutic keratectomy for recurrent corneal erosions. Eye 1994; 8:378–383 15. Wu WCS, Stark WJ, Green WR. Corneal wound healing after 193-nm excimer laser keratectomy. Arch Ophthalmol 1991; 109:1426–1432 16. John ME, Van der Karr MA, Noblitt RL, Boleyn KL. Excimer laser phototherapeutic keratectomy for treatment of recurrent corneal erosion. J Cataract Refract Surg 1994; 20:179–181 17. Morad Y, Haviv D, Zadok D, et al. Excimer laser phototherapeutic keratectomy for recurrent corneal erosion. J Cataract Refract Surg 1998; 24:451–455 ¨ rndahl M, et al. Pho18. Fagerholm P, Fitzsimmons TD, O totherapeutic keratectomy: long-term results in 166 eyes. Refract Corneal Surg 1993; 9(suppl):S76–S81
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19. Claoue´ C, Stevens J, Steele A. Band keratopathy and excimer laser phototherapeutic keratectomy. Eur J Implant Refract Surg 1995; 7:260–265 20. Campos M, Nielsen S, Szerenyi K, et al. Clinical followup of phototherapeutic keratectomy for treatment of corneal opacities. Am J Ophthalmol 1993; 115:433–440 21. Hersh PS, Spinak A, Garrana R, Mayers M. Phototherapeutic keratectomy: strategies and results in 12 eyes. Refract Corneal Surg 1993; 9(suppl):S90–S95 22. Dogru M, Katakami C, Yamanaka A. Refractive changes after excimer laser phototherapeutic keratectomy. J Cataract Refract Surg 2001; 27:686–692 23. Helena MC, Talamo JH. PTK complications. In: Azar DT, Steinert RF, Stark WJ, eds, Excimer Laser Phototherapeutic Keratectomy. Baltimore, MD, Williams & Wilkins, 1997; 143–153 24. Dausch D, Landesz M, Klein R, Schro¨der E. Phototherapeutic keratectomy in recurrent corneal epithelial erosion. Refract Corneal Surg 1993; 9:419–424 25. Algawi K, Goggin M, O’Keefe M. 193 nm excimer laser phototherapeutic keratectomy for recurrent corneal erosions. Eur J Implant Refract Surg 1995; 7:11–13 26. Tuunanen TH, Tervo TM. Excimer laser phototherapeutic keratectomy for corneal diseases: a follow-up study. CLAO J 1995; 21:67–72
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27. McDonnell PJ, Seiler T. Phototherapeutic keratectomy with excimer laser for Reis-Bu¨ckler’s corneal dystrophy. Refract Corneal Surg 1992; 8:306–310 28. Talamo JH, Steinert RF, Puliafito CA. Clinical strategies for excimer laser therapeutic keratectomy. Refract Corneal Surg 1992; 8:319–324 29. John ME, Martines E, Cvintal T, et al. Phototherapeutic keratectomy following penetrating keratoplasty. J Refract Corneal Surg 1994; 10:S206–S210 30. Gibralter R, Trokel SL. Correction of irregular astigmatism with the excimer laser. Ophthalmology 1994; 101: 1310–1314 31. Lawless MA, Cohen PR, Rogers CM. Retreatment of undercorrected photorefractive keratectomy for myopia. J Refract Corneal Surg 1994; 10:S174–S177 From the Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic. Presented in part at the XXth Congress of the European Society of Cataract & Refractive Surgeons, Nice, France, September 2002. Supported by University Hospital Brno, Brno, Czech Republic. None of the authors has a financial or proprietary interest in any material or method mentioned.
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T
he use of excimer lasers in ophthalmic surgery was first described by Trokel and coauthors in 1983.1 Serdarevic and coauthors2 proposed the first therapeutic use of the excimer laser to treat experimental Candida infectious keratitis in 1985. The first phototherapeutic
Accepted for publication January 20, 2004. Reprint requests to Rudolf Autrata, MD, PhD, Department of Ophthalmology, Masaryk University Hospital, Cernopolni 9, Brno 61300, Czech Republic. E-mail: [email protected]. 2004 ASCRS and ESCRS Published by Elsevier Inc.
keratectomy (PTK) procedure in a sighted eye was performed by Gartry and coauthors3 in 1988. Experimental and clinical research on the successful removal of superficial corneal opacities with the attainment of smooth regular corneal surfaces and visual acuity improvement has prompted extensive use of PTK with excimer lasers.1–9 The current clinical practice of excimer laser PTK has expanded to treat a range of corneal disorders. Generally, excimer laser PTK is used to remove superficial corneal stromal opacities (eg, postinfectious traumatic 0886-3350/04/$–see front matter doi:10.1016/j.jcrs.2004.02.047
PHOTOTHERAPEUTIC KERATECTOMY IN CHILDREN
scarring and anterior stromal dystrophies), treat or smooth irregular surface disorders, treat epithelial instability and reepithelialization failure (eg, in recurrent corneal erosion syndrome and vernal keratoconjunctivitis), and reduce iatrogenically produced refractive errors including induced irregular astigmatism after cataract surgery, penetrating keratoplasty (PKP), and other procedures. The diagnostic indication for PTK can fall into several categories; eg, rough band keratopathy, which may present with visual symptoms and ocular pain. In patients with good visual potential, particular care must be taken to avoid excessive refractive changes and irregular astigmatism. Clinical studies of the use of PTK in pediatric patients are limited to a few reports of a few sample cases. In this study, we examined the clinical features and visual and refractive changes in children with superficial corneal opacities after PTK performed with the Nidek EC-5000 excimer laser system. We evaluated the efficacy and safety of PTK for the treatment of superficial corneal opacities, surface irregularities, and epithelial instability. To our knowledge, this is the first study of PTK in a relatively large group of children with a long-term follow-up.
Patients and Methods The retrospective study comprised consecutive pediatric patients who had excimer laser PTK at Masaryk University Hospital Eye Clinic from September 1996 to January 2000. Indications for PTK included recurrent corneal epithelial erosions, superficial scars or a persistent epithelial defect after keratitis, lagophthalmos, dry spots and mucous plaques in vernal keratoconjunctivitis, band keratopathy, anterior corneal dystrophies, corneal scars secondary to postinfectious keratitis, and previous trauma. The main treatment goals were to improve visual acuity and reduce or eliminate subjective ocular discomfort; ie, pain, lacrimation, and photophobia. All parents were given a detailed explanation of the procedure and the risks/benefits of the laser treatment. They signed a consent form detailing their understanding of PTK or PTK combined with photorefractive keratectomy (PRK) for their child. The research was approved by the Masaryk University Children Hospital‘s institutional review board/ ethics committee. Approval of the ethics committee for PTK in children was obtained before the surgical procedures. All patients had routine ophthalmic examinations that included uncorrected visual acuity and best spectacle-corrected visual acuity (BSCVA), manifest and cycloplegic 1910
(cyclopentolate) refractions (Nidek ARK800), biomicroscopy, videokeratoscopy (C-scan, Technomed), pachymetry (Nidek UP1000), tonometry (Goldmann tonometry and Tono-Pen威 [Medtronic Solan]), Schirmer test, and fundoscopy by indirect binocular ophthalmoscopy. After treatment, the patients were examined daily for the first postoperative week; at 1, 3, 6, 9, and 12 months; and then after 6 months. All examinations and laser procedures were performed by the same ophthalmologist (R.A.). The PTK procedure was performed under topical anesthesia with oxybuprocaine hydrochloride 0.5%; no general pharmacologic pretreatment was administered. The Nidek EC-5000 excimer laser was calibrated before each treatment by ablating a poly(methyl methacrylate) card to ⫺3.0 diopters (D). The treatment zone was 6.0 to 7.5 mm, and the transition zone of 1.0 mm was set beyond the ablation zone in all procedures. The ablation depth was 18 to 120 m, and the pulse frequency was 30 Hz. Hydroxypropyl methylcellulose 1% solution was used as the masking agent as needed during the procedure to achieve a smoother ablation. In 2 eyes with smooth band keratopathy, the epithelium was used as a smoothing template for the transepithelial laser ablation. However, in 3 cases of rough band keratopathy, large calcified plaques were removed using mechanical debridement before laser ablation. In the combined procedure, PRK was performed immediately after PTK. The amount of PRK was generally set at the pretreatment refraction. The maximum spherical diopters of hyperopic laser correction was based on preoperative measurements, but only 30% to 50% of diopters of preoperative myopia was set because post-PTK treatment hyperopic shift usually occurs and correlates with stromal ablation depth. The decision to reduce the myopic correction in combined cases by 30% to 50% was based on our experience with 128 PTK procedures in adult patients. In these patients, at 3 years, the mean final hyperopic shift was ⫹1.73 D ⫾ 1.46 (SD) for the 6.5 mm optical zone and the mean central ablation depth was 61.34 ⫾ 23.51 m. Subsequently, every 10 m of PTK ablation depth caused a mean 0.282 D hyperopic shift. This calculation was used for setting parameters in the combined pediatric cases. An additional consideration was the refraction in the second eye of each patient because our goal was postoperative myopic isometropia. In myopic PRK, the largest optical zone of 6.5 mm (transition zone 7.5 mm) was used and in hyperopic PRK, the 5.5 mm optical zone (transition zone 9.0 mm). The cornea was cooled before and after ablation with 10oC sterile balanced salt solution (BSS威). At the end of the procedure, a drop of tobramycin (Tobrex威) and a drop of diclofenac (Naclof威) were administered and a therapeutic contact lens (Acuvue威, base curve 9.1 mm, Vistakon) was applied to the eye. The therapeutic contact lens remained in situ for 3 to 4 days postoperatively. The patients were seen daily in our department as hospital inpatients until the epithelial defect healed. Tobrex was instilled 5 times daily for the first postop-
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erative week, and fluorometholone 0.1% (Flucon威) ophthalmic drops were administered 5 times daily for 1 month and then tapered over 6 months. The Student t test, Mann-Whitney test (analysis of nonparametric values), and Fisher exact test (analysis of categorized data) were used for statistical analysis. Ninety-five percent confidence interval limits were calculated for differences in mean results. Continuous variables were described with mean, standard deviation, and minimum and maxium values. A P value of less than 0.05 was considered statistically significant. Statistical analysis was performed with the cooperation of the Institute of Medical Statistics at Masararyk University, Brno.
Results Forty-one consecutive pediatric patients (41 eyes) were included. Twenty-three eyes had PTK only; 18 eyes were treated with combined PTK and PRK to reduce preoperative myopia (11 eyes) or hyperopia (7 eyes). The mean age of the patients was 11.4 ⫾ 4.65 years (range 8 to 18 years). The mean follow-up was 4.8 ⫾ 1.9 years (range 3 to 6 years). Clinical Features Superficial corneal opacities were successfully removed from the ablation zone and the corneal visual
axis in all patients. Nine eyes with recurrent corneal erosion syndrome preoperatively had no recurrences during follow-up. Ocular pain or discomfort, lacrimation, and photophobia that patients reported preoperatively were not reported after PTK. Complete and uneventful corneal reepithelialization occurred in all eyes within 5 days of the procedures. The mean reepithelialization time in the PTK-only group and the group with combined PTK and myopic PRK (6.5 mm ablation zone, 7.5 mm transition zone) was 2.5 ⫾ 0.7 days; in the group with combined PTK and hyperopic PRK (9.0 mm ablation zone), it was 3.85 ⫾ 1.25 days. The difference was statistically significant (P⬍.05). Visual Outcome The mean BSCVA in all eyes was 0.21 ⫾ 0.23 (range 0.63 to 0.016) preoperatively and 0.57 ⫾ 0.34 (range 1.0 to 0.1) at the last examination. The difference was statistically significant (P ⫽ .0246). Visual acuity before and after PTK (or PTK combined with PRK) in each diagnostic group of corneal disorders is shown in Table 1. The gain in Snellen lines of BSCVA at the last examination is shown in Figure 1. Twenty-eight eyes
Table 1. The BSCVA preoperatively and at the last examination (3 to 6 months) after PTK or PTK combined with PRK. Number of Eyes (%)
Mean Preop BSCVA (Range)
Mean Postop BSCVA (Range)
Recurrent corneal erosion syndrome
9 (22.0)
6/24 (6/12 to 6/38)
6/10 (6/6 to 6/15)
Persistent epithelial defect
7 (17.0)
6/38 (6/15 to 3/60)
6/15 (6/7.5 to 6/30)
Dry spot or mucous plaque (atopic or vernal keratoconjunctivities)
5 (12.2)
6/20 (6/12 to 4/60)
6/10 (6/5 to 6/20)
Band keratopathy
5 (12.2)
6/60 (6/38 to 1/60)
6/15 (6/10 to 6/48)
Cogan’s
1 (2.4)
6/30
6/10
Messmann’s
1 (2.4)
6/24
6/6
Reis-Ruckler’s
5 (12.2)
6/60 6/30 to 3/60
6/12 6/10 to 6/20
Posttraumatic superficial corneal scar
2 (4.8)
6/38 and 6/60
6/12 and 6/15
Postherpetic entral superficial scar
4 (9.6)
6/60 (6/38 to 3/60)
6/15 (6/12 to 6/24)
Recurrent posttraumatic pseudopterygium
2 (4.8)
6/12 and 6/10
6/7.5 and 6/10
41 (100)
6/30 (6/10 to 1/60)
6/10 (6/5 to 6/48)
Diagnosis
Corneal dystrophy
Total BSCVA ⫽ best spectacle-corrected visual acuity
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Figure 1. (Autrata) Change in BSCVA at the last examination (3
Figure 2. (Autrata) Hyperopic shift post PTK shown over time.
to 6 years after PTK or combined PTK and PRK) expressed as a gain of Snellen lines (n ⫽ 41).
Induced hyperopia peaked in the first 2 months, decreased over time, and stabilized at 12 months (n ⫽ 23).
(68.3%) gained 3 or more lines, 7 eyes (17.0%) gained 2 lines, and 5 eyes (12.2%) gained 1 line. No eye lost a line of BSCVA.
In the 11 myopic eyes, the mean spherical equivalent (SE) refraction was ⫺5.32 ⫾ 2.21 D (range ⫺2.50 to ⫺7.75 D) preoperatively and ⫺1.16 ⫾ 1.54 D (range ⫹1.25 to ⫺3.75 D) 2 years after combined PTK and myopic PRK (Figure 3). In the 7 hyperopic eyes, the mean SE refraction was ⫹4.72 ⫾ 2.58 D (range ⫹2.25 to ⫹6.50 D) preoperatively and ⫹1.52 ⫾ 1.77 D (range ⫹0.75 to ⫹3.75 D) 2 years after combined PTK and hyperopic PRK (Figure 4). The postoperative reduction in the mean SE refraction in the myopic and hyperopic eyes (n ⫽ 18) was statistically significant (P⬍.05).
Refractive Changes In the 23 PTK-only eyes, the mean hyperopic shift was 2.14 ⫾ 1.17 D (range ⫹0.25 to ⫹3.50 D) at 2 years and 2.23 ⫾ 1.29 D (range ⫹0.50 to ⫹3.75 D) at 1 year. The difference was not statistically significant. The induced hyperopia peaked at the first month (mean 3.76 ⫾ 1.84 D) and tended to decrease after that, with stabilization at 12 months (Figure 2). At 3 years, the mean refractive change was ⫹2.09 ⫾ 1.21 D and the mean central ablation depth was 52.41 ⫾ 31.56 m. An ablation depth of 10 m resulted in 0.39 D of the mean hyperopic shift at the final examination. The mean central keratometry was 42.15 ⫾ 1.47 D before PTK, 38.96 ⫾ 1.75 D at 6 months (P⬍.05), and 39.41 ⫾ 1.67 D at 12 months. The difference between 6 and 12 months was not statistically significant.
Complications No visually disabling complications related to PTK and PRK were observed. Nine eyes (21.9%) developed grade I or II subepithelial haze at 1 to 3 months. The haze disappeared gradually within 12 to 18 months and did not affect the BSCVA. No eye developed adverse reactions to topical steroids (eg, an intraocular pressure increase).
Figure 3. (Autrata) Change in the mean SE refraction 2 years after
Figure 4. (Autrata) Change in the mean SE refraction 2 years after
PTK combined with myopic PRK (n ⫽ 11).
PTK combined with hyperopic PRK (n ⫽ 7).
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There were no postoperative complications such as infection, epithelial healing problems, corneal melt, or recurrences after PTK for corneal erosion syndrome. The PTK was well tolerated by all children, who reported mild pain or discomfort at days 1 to 3.
Discussion Phototherapeutic keratectomy has been performed and evaluated for at least 10 years in adult patients and has proved successful. The encouraging anatomic and visual results in studies of PTK for superficial corneal opacities and irregularities in the adult population have led to widespread approval of the procedure among ophthalmologists and patients.10–14 The 193 nm excimer laser has been used to treat recurrent corneal erosion syndrome and anterior stromal and superficial scarring from postinfectious and posttraumatic causes, including inactive herpes simplex virus keratitis, anterior corneal dystrophies, and band keratopathy.8,13,15–17 Most clinical studies report the results of PTK in adult patients. We evaluated the clinical features and visual and refractive changes in children with superficial corneal disorders after PTK or PTK combined with PRK performed with the Nidek EC-5000 excimer laser and followed for more than 2 years. Many authors report induced refractive changes, mainly a hyperopic shift, as a complication of treatment.3,18–21 With Bowman’s layer ablated, the hyperopic shift increases with the depth of treatment. In our study, we found a mean hyperopic shift of ⫹2.14 D 2 years after PTK (without additional PRK) in 23 pediatric eyes with various superficial corneal disorders. In all patients, we used a 5.0 to 6.5 mm ablation zone with a 7.5 mm transition zone, an ablation depth of 18 to 120 m, and a masking agent. Dogru and coauthors22 conclude that a shallow ablation depth (less than 100 m), the presence of a transition zone setting, and the use of a masking substance significantly reduce the hyperopic shift. The use of fluid-shielding agents is not routine in every PTK procedure, eg, in the treatment of recurrent epithelial erosions, and masking the surface of Bowman’s layer is rarely required. Although the ablation depth depends on individual corneal pathology, we believed an ablation depth of less than 100 m was sufficient to successfully treat all corneal opacities and surface corneal disorders in our series. A correlation
between ablation depth, ablation zone diameter, transition zone, and hyperopic shift has been detected.23 Hyperopic shift can be minimized by adding hyperopic treatment to the plano treatment. However, shifts in refraction after PTK are unpredictable in degree and direction, possibly because of underlying pathology. In our study, with a follow-up of 3 to 6 years after PTK and combined PTK and PRK, the mean SE refraction was stabilized at 12 months. Recurrent erosions represent an early indication for PTK treatment. No studies of PTK for recurrent erosions in pediatric cases have been published. In cases of recurrent corneal erosion syndrome, PTK has been reserved for patients in whom conventional medical treatments, including topical lubricants and hyperosmotic solutions, mechanical debridement, and soft contact lenses, have failed. A large, single, central ablation zone (5.0 to 6.5 mm) is recommended for paracentral or axial epithelial abnormalities to avoid possible irregular astigmatism. Most patients are symptom free within the first few days of treatment and have no recurrences.14,17,24 In our pediatric group of 9 eyes with recurrent erosions, no eye had a recurrence during follow-up. The mechanism by which excimer laser ablation prevents recurrent corneal erosion may lie in the strong bonds formed between the epithelial basement membrane and Bowman’s layer or the stromal bed postoperatively. The presence of persistent corneal haze after PTK for recurrent erosions is rare due to the shallow ablation depth. Most investigators4,14,16,25 report no adverse effects on visual acuity after PTK for recurrent epithelial erosions in adult patients. This was the same in our pediatric patients. In band keratopathy, there is extracellular deposition of granular material in the epithelial basement membrane, Bowman’s layer, and anterior stroma. The material usually consists of calcium phosphate and carbonate salts. Single axial ablation zones restricted to the anterior 100 m of the stroma result in visual acuity improvement with a reduction in complications including irregular astigmatism and hyperopic shift.13,19 No studies of PTK for band keratopathy in children have been published. In our group of children, 5 eyes had band keratopathy; their mean BSCVA improved from 6/60 (range 6/38 to 1/60) preoperatively to 6/15 (range 6/9 to 6/48) 3 to 6 years after PTK. The corneal clarity in all eyes remained improved, with no recurrence of
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Figure 5. (Autrata) The cornea of a 12-year-old boy with Reis-
Figure 6. (Autrata) The cornea in Figure 5, 3 years after PTK
Buckler’s dystrophy and painful recurrent corneal erosion syndrome. The BSCVA was 6/60 with an SE refraction of ⫹6.25 D.
(50 m ablation depth) combined with hyperopic PRK of ⫹6.50 D. The BSCVA was 6/12 with an SE refraction of ⫹2.75 D. There were no postoperative recurrences of epithelial erosions.
band keratopathy in the treated zone. Phototherapeutic keratectomy appears to be a successful treatment option for smooth band keratopathy to relieve the associated pain and improve corneal clarity and therefore visual acuity in potentially sighted eyes. The combined treatment using manual scraping, ethylenediaminetetraacetic acid, and excimer laser ablation is better suited to cases with coarse irregular changes with flakes of calcification. The objectives of excimer PTK for the treatment of corneal dystrophies overlap those for other corneal pathologies: Painful recurrent corneal erosions may be prominent in Cogan’s and Reis-Buckler’s dystrophies, whereas reduced vision secondary to the subepithelial opacities of Reis-Buckler’s dystrophy and loss of anterior stromal clarity in granular and lattice dystrophies provide optical indications for treatment. Fagerholm et al.18 report 27 patients with corneal dystrophy. Twentyone (77.8%) achieved a long-term therapeutic goal of improved visual acuity. Tuunanen and Tervo26 report improved BSCVA in 4 of 5 cases of corneal dystrophy. Ablation of the epithelium overlying irregular anterior stromal opacities in certain cases of corneal dystrophy may be beneficial.20,27 In our pediatric group of 7 eyes with corneal dystrophy, the BSCVA improved in all cases (Table 1). Two eyes with Reis-Buckler’s dystrophy received combined PTK and hyperopic PRK. In the first eye, the preoperative SE refraction of ⫹6.25 D improved and stabilized at ⫹2.75 D and the BSCVA of 6/60 improved to 6/12 at 36 months (Figures 5 and 6). In the second eye, the preoperative refraction (SE)
of ⫹4.25 D decreased to ⫹1.50 D and the BSCVA of 6/60 improved to 6/9. In conditions in which the corneal opacities are anteriorly placed, PTK appears to be a promising alternative to lamellar keratoplasty or PKP. Phototherapeutic keratectomy has been used to treat anterior stromal corneal scars secondary to various etiologies including postinfectious keratitis and after trauma. Masking agents are used during the procedure, and slitlamp biomicroscopy is performed frequently to gauge treatment progress. Phototherapeutic keratectomy has also been effective in the treatment of postherpes simplex corneal scarring. Fagerholm et al.18 report 15 such patients, including 2 children treated under general anesthesia, with a mean follow-up of 15.7 months. Eighty percent of the eyes achieved 3 or more Snellen lines of improved visual acuity. Campos et al.20 used prophylactic systemic acyclovir in a patient with a postherpetic scar and lattice dystrophy. No recurrence of herpetic keratitis occurred during the 15-month follow-up. Talamo and coauthors28 pretreated a patient with trifluorothymidine daily for several days before PTK for a herpes simplex scar that had shown no clinical signs of active keratitis for more than 1 year. In our study, PTK was performed for a postherpetic central scar in 4 eyes. The children were treated with oral acyclovir for 2 days before PTK and for 10 days after the procedure. All 4 eyes gained 3 or more Snellen lines of BSCVA, and no reactivation of the keratitis was recorded during more than 3 years of follow-up.
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Two of the eyes had combined PTK and PRK with successful visual and refractive outcomes. Relatively small numbers of posttraumatic scars treated by PTK have been reported.4,18,20,26 In our series, 2 children with a central posttraumatic scar gained more than 3 Snellen lines of visual acuity; the improvement remained throughout the follow-up. In some circumstances, combined PTK and PRK is appropriate. The PTK and PRK may be indicated for an associated corneal opacity or persistent epithelial defects with preoperative myopia, hyperopia, and astigmatism. Combined PTK and PRK has been performed for recurrent dystrophies after PKP21,29 and to treat irregular astigmatism. Gibralter and Trokel30 describe a method of incorporating combined PTK and PRK. Lawless and coauthors31 report 14 eyes that required a dual PTK and PRK treatment for manifest scarring and regression unresponsive to topical corticosteroids after an initial myopic PRK. A 5.0 mm transepithelial PTK ablation zone was used, and then PRK was performed. During a follow-up of 1 to 9 months, no scarring redeveloped and no significant refractive regression occurred. The eyes appeared to stabilize more rapidly than after the primary PRK. These promising results suggest a future role for PTK combined with PRK in the management of challenging problems of surface or anterior stromal corneal pathology and a refractive error and iatrogenically induced refractive astigmatism. In PRK, no generalized surgical plan can be used to treat various corneal disorders that have yielded or may yield to the precision of excimer laser PTK. Thus, it remains the responsibility of the ophthalmic surgeon to carefully choose and counsel patients suitable for PTK treatment and to tailor the subsequent PTK strategy on an individual basis. Based on our study results, PTK seems to be an effective and safe procedure in children to treat various surface corneal disorders. Phototherapeutic keratectomy can improve the best corrected visual acuity and eliminate ocular pain and irritation as symptoms of these ocular surface pathologies. In our study, combined PTK and PRK procedures resulted in effective reduction of the preoperative refractive errors.
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2. Serdarevic O, Darrell RW, Krueger RR, Trokel SL. Excimer laser therapy for experimental Candida keratitis. Am J Ophthalmol 1985; 99:534–538 3. Gartry D, Kerr Muir M, Marshall J. Excimer laser treatment of corneal surface pathology: a laboratory and clinical study. Br J Ophthalmol 1991; 75:258–269 4. Fo¨rster W, Grewe S, Atzler U, et al. Phototherapeutic keratectomy in corneal diseases. Refract Corneal Surg 1993; 9(suppl):S85–S90 ¨ rndahl M, Fagerholm P, Fitzsimmons T, Tengroth B. 5. O Treatment of corneal dystrophies with excimer laser. Acta Ophthalmol 1994; 72:235–240 6. Kozobolis VP, Siganos DS, Meladakis GS, Pallikaris IG. Excimer laser phototherapeutic keratectomy for corneal opacities and recurrent erosion. J Refract Surg 1996; 12: S288–S290 7. Hahn TW, Sah WJ, Kim JH. Phototherapeutic keratectomy in nine eyes with superficial corneal diseases. Refract Corneal Surg 1993; 9(suppl):S115–S118 8. Nassaralla BA, Garbus J, McDonnell PJ. Phototherapeutic keratectomy for granular and lattice corneal dystrophies at 1.5 to 4 years. J Refract Surg 1996; 12:795–800 9. Thompson V, Durrie DS, Cavanaugh TB. Philosophy and technique for excimer laser phototherapeutic keratectomy. Refract Corneal Surg 1993; 9(suppl):S81–S85 10. Lohmann CP, Sachs H, Marshall J, Gabel V-P. Excimer laser phototherapeutic keratectomy for recurrent erosions: a clinical study. Ophthalmic Surg Lasers 1996; 27: 768–771 11. Thompson VM. Excimer laser phototherapeutic keratectomy: clinical and surgical aspects. Ophthalmic Surg Lasers 1995; 26:461–472 12. Hersh PS, Burnstein Y, Carr J, et al. Excimer laser phototherapeutic keratectomy; surgical strategies and clinical outcomes. Ophthalmology 1996; 103:1210–1222 13. O‘Brart DPS, Gartry DS, Lohmann CP, et al. Treatment of band keratopathy by excimer laser phototherapeutic keratectomy: surgical techniques and long term follow up. Br J Ophthalmol 1993; 77:702–708 14. O‘Brart DPS, Kerr Muir MG, Marshall J. Phototherapeutic keratectomy for recurrent corneal erosions. Eye 1994; 8:378–383 15. Wu WCS, Stark WJ, Green WR. Corneal wound healing after 193-nm excimer laser keratectomy. Arch Ophthalmol 1991; 109:1426–1432 16. John ME, Van der Karr MA, Noblitt RL, Boleyn KL. Excimer laser phototherapeutic keratectomy for treatment of recurrent corneal erosion. J Cataract Refract Surg 1994; 20:179–181 17. Morad Y, Haviv D, Zadok D, et al. Excimer laser phototherapeutic keratectomy for recurrent corneal erosion. J Cataract Refract Surg 1998; 24:451–455 ¨ rndahl M, et al. Pho18. Fagerholm P, Fitzsimmons TD, O totherapeutic keratectomy: long-term results in 166 eyes. Refract Corneal Surg 1993; 9(suppl):S76–S81
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19. Claoue´ C, Stevens J, Steele A. Band keratopathy and excimer laser phototherapeutic keratectomy. Eur J Implant Refract Surg 1995; 7:260–265 20. Campos M, Nielsen S, Szerenyi K, et al. Clinical followup of phototherapeutic keratectomy for treatment of corneal opacities. Am J Ophthalmol 1993; 115:433–440 21. Hersh PS, Spinak A, Garrana R, Mayers M. Phototherapeutic keratectomy: strategies and results in 12 eyes. Refract Corneal Surg 1993; 9(suppl):S90–S95 22. Dogru M, Katakami C, Yamanaka A. Refractive changes after excimer laser phototherapeutic keratectomy. J Cataract Refract Surg 2001; 27:686–692 23. Helena MC, Talamo JH. PTK complications. In: Azar DT, Steinert RF, Stark WJ, eds, Excimer Laser Phototherapeutic Keratectomy. Baltimore, MD, Williams & Wilkins, 1997; 143–153 24. Dausch D, Landesz M, Klein R, Schro¨der E. Phototherapeutic keratectomy in recurrent corneal epithelial erosion. Refract Corneal Surg 1993; 9:419–424 25. Algawi K, Goggin M, O’Keefe M. 193 nm excimer laser phototherapeutic keratectomy for recurrent corneal erosions. Eur J Implant Refract Surg 1995; 7:11–13 26. Tuunanen TH, Tervo TM. Excimer laser phototherapeutic keratectomy for corneal diseases: a follow-up study. CLAO J 1995; 21:67–72
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27. McDonnell PJ, Seiler T. Phototherapeutic keratectomy with excimer laser for Reis-Bu¨ckler’s corneal dystrophy. Refract Corneal Surg 1992; 8:306–310 28. Talamo JH, Steinert RF, Puliafito CA. Clinical strategies for excimer laser therapeutic keratectomy. Refract Corneal Surg 1992; 8:319–324 29. John ME, Martines E, Cvintal T, et al. Phototherapeutic keratectomy following penetrating keratoplasty. J Refract Corneal Surg 1994; 10:S206–S210 30. Gibralter R, Trokel SL. Correction of irregular astigmatism with the excimer laser. Ophthalmology 1994; 101: 1310–1314 31. Lawless MA, Cohen PR, Rogers CM. Retreatment of undercorrected photorefractive keratectomy for myopia. J Refract Corneal Surg 1994; 10:S174–S177 From the Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic. Presented in part at the XXth Congress of the European Society of Cataract & Refractive Surgeons, Nice, France, September 2002. Supported by University Hospital Brno, Brno, Czech Republic. None of the authors has a financial or proprietary interest in any material or method mentioned.
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