Corneal epithelial healing after photorefractive keratectomy: Analytical study

Purpose: To characterize the velocity of epithelial migration after photorefractive keratectomy (PRK) with 3 different corneal ablation patterns. Setting: Department of Ophthalmology, Catholic University of Rome, Rome, Italy. Methods: Fifteen patients (30 eyes) with mild to moderate myopia and with simple to compound myopic astigmatism were enrolled for this study. The surgical procedure consisted of standardized PRK with final smoothing performed using the Technolas Keracor 217C excimer laser. The reepithelialization process was evaluated at 0 hours, 20 hours, 40 hours, and 60 hours after surgery using a digital photo camera and custom software for measurement. Digital analysis of the images was performed. Corneal topographies were taken at 1 month, 3 months, 6 months, and 12 months after PRK. Results: The mean speed of radial migration in the 10 eyes (33%) in the low spherical ablation group was 0.087 mm/h ± 0.008 (SD). This was significantly higher than that found in the 10 eyes (33%) in the high spherical ablation group (mean speed 0.078 ± 0.007 mm/h; P<.001) and in the 10 eyes (33%) in the cross‐cylinder ablation group (mean speed 0.055 ± 0.014 mm/h; P<.001). Conclusion: Analysis of the data shows that epithelial migration along the photoablated corneal surface depends on the ablation pattern. The epithelial sliding is highly influenced by local variations in the curvature of the stromal surface. The data demonstrate that faster epithelial wound healing after PRK is predictive of optimal visual performance.

[1]  P. Khaw,et al.  Corneal stem cells in review , 2001, Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society.

[2]  M. Lombardo,et al.  One-year results of photorefractive keratectomy with and without surface smoothing using the technolas 217C laser. , 2004, Journal of refractive surgery.

[3]  M. Doğru,et al.  Refractive changes after excimer laser phototherapeutic keratectomy , 2001, Journal of cataract and refractive surgery.

[4]  T. Møller-Pedersen,et al.  The cellular basis of corneal transparency: evidence for 'corneal crystallins'. , 1999, Journal of cell science.

[5]  M. Lombardo,et al.  Smoothing of the ablated porcine anterior corneal surface using the Technolas Keracor 217C and Nidek EC-5000 excimer lasers. , 2004, Journal of refractive surgery.

[6]  M. Lombardo,et al.  Photorefractive keratectomy with and without smoothing: a bilateral study. , 2003, Journal of refractive surgery.

[7]  R. Maloney,et al.  Determination of corneal image-forming properties from corneal topography. , 1993, American journal of ophthalmology.

[8]  S. Wilson,et al.  Molecular cell biology for the refractive corneal surgeon: programmed cell death and wound healing. , 1997, Journal of refractive surgery.

[9]  J. Marshall,et al.  Growth factors in corneal wound healing following refractive surgery: A review. , 2002, Acta ophthalmologica Scandinavica.

[10]  G. Waring,et al.  Regional variation in corneal topography and wound healing following photorefractive keratectomy. , 1995, Journal of refractive surgery.

[11]  M. Berns,et al.  Scanning electron microscopy comparison of corneal epithelial removal techniques before photorefractive keratectomy. , 1999, Journal of cataract and refractive surgery.

[12]  I. Zagon,et al.  Reepithelialization of the human cornea is regulated by endogenous opioids. , 2000, Investigative ophthalmology & visual science.

[13]  David Huang,et al.  Spot size and quality of scanning laser correction of higher‐order wavefront aberrations , 2002, Journal of cataract and refractive surgery.

[14]  T. Nishida,et al.  Ocular surface changes after excimer laser phototherapeutic keratectomy. , 2000, Ophthalmology.

[15]  T. Møller-Pedersen,et al.  Confocal microscopic characterization of wound repair after photorefractive keratectomy. , 1998, Investigative ophthalmology & visual science.

[16]  J. Israelachvili,et al.  Thin film rheology and lubricity of hyaluronic acid solutions at a normal physiological concentration. , 2002, Journal of biomedical materials research.

[17]  G. Wilson,et al.  The cell shedding rate of the corneal epithelium--a comparison of collection methods. , 1996, Current eye research.

[18]  I. Pallikaris,et al.  Corneal epithelial wound healing after excimer laser photorefractive and photoastigmatic keratectomy (PRK and PARK). , 1999, Cornea.

[19]  M. Azzolini,et al.  Effect of decreasing surface and interface irregularities after photorefractive keratectomy and laser in situ keratomileusis on optical and functional outcomes. , 1998, Journal of refractive surgery.

[20]  G O Waring,et al.  Effect of excimer laser radiant exposure on uniformity of ablated corneal surface , 1989, Lasers in surgery and medicine.

[21]  S. Klyce,et al.  Epithelial wound closure in the rabbit cornea. A biphasic process. , 1986, Investigative ophthalmology & visual science.

[22]  M. Azzolini,et al.  Photorefractive keratectomy to correct myopic or hyperopic astigmatism with a cross-cylinder ablation. , 1999, Journal of refractive surgery.

[23]  C. Puliafito,et al.  A comparative study of masking fluids for excimer laser phototherapeutic keratectomy. , 1991, Archives of ophthalmology.

[24]  P. McDonnell,et al.  Excimer laser smoothing of a reproducible model of anterior corneal surface irregularity. , 1991, Ophthalmology.

[25]  S. Klyce,et al.  Gender- and Age-related Differences in Corneal Topography , 2001, Cornea.

[26]  D. O'leary,et al.  Size and Number of Epithelial Cells Washed from the Cornea after Contact Lens Wear , 1998, Optometry and vision science : official publication of the American Academy of Optometry.

[27]  A Singh,et al.  Corneal epithelial wound healing. , 1994, The British journal of ophthalmology.

[28]  T Kohnen,et al.  Format for reporting refractive surgical data , 1998, Journal of cataract and refractive surgery.

[29]  T. Møller-Pedersen,et al.  Quantification of stromal thinning, epithelial thickness, and corneal haze after photorefractive keratectomy using in vivo confocal microscopy. , 1997, Ophthalmology.

[30]  H. Hamberg‐Nyström,et al.  Cellular proliferation and leukocyte infiltration in the rabbit cornea after photorefractive keratectomy. , 2001, Acta ophthalmologica Scandinavica.

[31]  R. Mohan,et al.  The wound healing response after laser in situ keratomileusis and photorefractive keratectomy: elusive control of biological variability and effect on custom laser vision correction. , 2001, Archives of ophthalmology.

[32]  H. Kresse,et al.  Electron microscopic and immunohistochemical examination of scarred human cornea re-treated by excimer laser , 2002, Graefe's Archive for Clinical and Experimental Ophthalmology.

[33]  G O Waring,et al.  Wound healing after excimer laser keratomileusis (photorefractive keratectomy) in monkeys. , 1990, Archives of ophthalmology.

[34]  T. Møller-Pedersen,et al.  Stromal wound healing explains refractive instability and haze development after photorefractive keratectomy: a 1-year confocal microscopic study. , 2000, Ophthalmology.

[35]  E. Haaskjold,et al.  Pilot study on the time course of apoptosis in the regenerating corneal epithelium. , 2002, Acta ophthalmologica Scandinavica.

[36]  F Carones,et al.  Broad beam vs. flying spot excimer laser: refractive and videokeratographic outcomes of two different ablation profiles after photorefractive keratectomy. , 2001, Journal of refractive surgery.

[37]  Q. Ren,et al.  Absorption of 308-nm excimer laser radiation by balanced salt solution, sodium hyaluronate, and human cadaver eyes. , 1990, Archives of ophthalmology.

[38]  I. Gipson,et al.  Reassembly of the anchoring structures of the corneal epithelium during wound repair in the rabbit. , 1989, Investigative ophthalmology & visual science.

[39]  E. Gaffney,et al.  The mathematical modelling of cell kinetics in corneal epithelial wound healing. , 1999, Journal of theoretical biology.

[40]  H. J. Griesser,et al.  Effect of porosity and surface hydrophilicity on migration of epithelial tissue over synthetic polymer. , 2000, Journal of biomedical materials research.