[Skip to Content]
[Skip to Content Landing]
August 1994

Quantitative Histological Studies of Primate Corneas After Excimer Laser Photorefractive Keratectomy

Author Affiliations

From the LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans. Dr Munnerlyn and Mr Clapham are employed by and have proprietary and financial interests in VISX Inc. At the time this study was done, Drs McDonald and Kaufman were consultants to VISX Inc. Dr Shofner currently has a financial interest in VISX Inc.

Arch Ophthalmol. 1994;112(8):1103-1110. doi:10.1001/archopht.1994.01090200109031

Objective:  To evaluate histological changes in the primate cornea after excimer laser photorefractive keratectomy (PRK) and to correlate them with clinical observations.

Methods:  Sixteen African green monkey (Cercopithecus aethiops sabaeus) corneas were examined by light and transmission electron microscopy 6 weeks to 18 months after 1.5- or 3-diopter PRK.

Results:  All specimens had a smooth stromal surface surrounded by a smooth, centrally tapered Bowman's layer. Epithelial thickness appeared to peak 12 months after PRK. The trend was for the epithelium to be thickest in the central-treated area; this phenomenon was more obvious in the 3-diopter—treated corneas. The numbers of activated keratocytes beneath the treated zone peaked at 4 months and decreased thereafter, while the numbers in the untreated areas decreased in the first 2 months after surgery, increased by 4 months, and did not change thereafter. Regenerated basal lamina averaged 86% intact over ablated areas; thickness was normal and no duplications were seen. Overall, the density of hemidesmosomes was significantly less in ablated areas compared with unablated areas.

Conclusions:  These findings support the relationship between clinical observations of corneal haze after PRK, reestablishment of the epithelial cell layer, and the potential for stromal remodeling by active fibroblastic keratocytes beneath the ablation zone. Overall, quantification of several morphological parameters indicated that the values for the treated zone tended, with time, to approach those of the untreated cornea after PRK.

Marshall J, Trokel S, Rothery S, Schubert H.  An ultrastructural study of corneal incisions induced by an excimer laser at 193 nm . Ophthalmology . 1985;92:749-758.Article
Bende T, Seiler T, Wollensak J.  Side effects in excimer corneal surgery: corneal thermal gradients . Graefes Arch Clin Exp Ophthalmol . 1988;226:277-280.Article
Goodman GL, Trokel SL, Stark WJ, Munnerlyn CR, Green WR.  Corneal healing following laser refractive keratectomy . Arch Ophthalmol . 1989;107:1799-1803.Article
Marshall J, Trokel S, Rothery S, Krueger RR.  Photoablative reprofiling of the cornea using an excimer laser: photorefractive keratectomy . Lasers Ophthalmol . 1986;1:21-48.
McDonald MB, Liu JC, Byrd TJ, et al.  Central photorefractive keratectomy for myopia: partially sighted and normally sighted eyes . Ophthalmology . 1991;98:1327-1337.Article
Seiler T, Wollensak J.  Myopic photorefractive keratectomy with the excimer laser . Ophthalmology . 1991;98:1156-1163.Article
Sher NA, Chen V, Bowers RA, et al.  The use of the 193-nm excimer laser for myopic photorefractive keratectomy in sighted eyes: a multicenter trial . Arch Ophthalmol . 1991;109:1525-1530.Article
Sher NA, Barak M, Daya S, et al.  Excimer laser photorefractive keratectomy in high myopia: a multicenter study . Arch Ophthalmol . 1992;110:935-943.Article
Stark WJ, Chamon W, Kamp MT, Enger CL, Rencs EV, Gottsh JD.  Clinical follow-up of 193-nm ArF excimer laser photokeratectomy . Ophthalmology . 1992;99:805-812.Article
Gartry DS, Muir MGK, Marshall J.  Excimer laser photorefractive keratectomy: 18-month follow-up . Ophthalmology . 1992;99:1209-1219.Article
Salz JJ, Maguen E, Nesburn AB, et al.  A two-year experience with excimer laser photorefractive keratectomy for myopia . Ophthalmology . 1993;100:873-882.Article
Eiferman RA, Forgey DR, Cook YD.  Excimer laser ablation of infectious crystalline keratopathy . Arch Ophthalmol . 1992;110:18.Article
McDonnell PJ, Moreira H, Clapham TN, D'Arcy J, Munnerlyn CR.  Photorefractive keratectomy for astigmatism: initial clinical results . Arch Ophthalmol . 1991;109:1370-1373.Article
McDonnell PJ, Seiler T.  Phototherapeutic keratectomy with excimer laser for Reis-Bückler's corneal dystrophy . Refract Corneal Surg . 1992;8:306-310.
Talamo JH, Steinert RF, Puliafito CA.  Clinical strategies for excimer laser therapeutic keratectomy . Refract Corneal Surg . 1992;8:319-324.
Frangie JP, Park SB, Kim H, Aquavella JV.  Excimer laser keratectomy after radial keratotomy . Am J Ophthalmol . 1193;115:634-639.
Gipson IK.  Corneal epithelial and stromal reactions to excimer laser photorefractive keratectomy, I: concerns regarding the response of the corneal epithelium to excimer laser ablation . Arch Ophthalmol . 1990;108:1539-1540.Article
Cintron C.  Corneal epithelial and stromal reactions to excimer laser photorefractive keratectomy, II: unpredictable corneal cicatrization . Arch Ophthalmol . 1990;108:1540-1541.Article
Wu WCS, Stark WJ, Green WR.  Corneal wound healing after 193-nm excimer laser keratectomy . Arch Ophthalmol . 1991;109:1426-1432.Article
Lohmann C, Gartry D, Muir MK, Timberlake G, Fitzke F, Marshall J.  'Haze' in photorefractive keratectomy: its origins and consequences . Laser Light Ophthalmol . 1991;4:15-34.
Hanna KD, Pouliquen YM. Waring GO III, Savoldelli M, Fantes F, Thompson KP.  Corneal wound healing in monkeys after repeated excimer laser photorefractive keratectomy . Arch Ophthalmol . 1992;110:1286-1291.Article
Gartry DS, Muir MGK, Lohmann CP, Marshall J.  The effect of topical corticosteroids on refractive outcome and corneal haze after photorefractive keratectomy: a prospective, randomized, double-blind trial . Arch Ophthalmol . 1992;110:944-952.Article
Carones F, Brancato R, Venturi E, Scialdone A, Bertuzzi A, Tavola A.  Efficacy of corticosteroids in reversing regression after myopic photorefractive keratectomy . Refract Corneal Surg . 1993;9( (suppl) ):S52-S56.
Tengroth B, Fagerholm P, Söderberg H, Hamberg-Nyström H, Epstein D.  Effect of corticosteroids in postoperative care following photorefractive keratectomies . Refract Corneal Surg . 1993;9( (suppl) ):S61-S64.
Wilson SE.  Excimer laser (193 nm) myopic keratomileusis in sighted and blind human eyes . Refract Corneal Surg . 1990;6:383-385.
Caubert E.  Cause of subepithelial corneal haze over 18 months after photorefractive keratectomy for myopia . Refract Corneal Surg . 1993;9( (suppl) ):S65-S70.
Campos M, Wang XW, Hertzog L, et al.  Ablation rates and surface ultrastructure of 193-nm excimer laser keratectomies . Invest Ophthalmol Vis Sci . 1993;34:2493-2500.
Hanna KD, Pouliquen YM, Savoldelli M, et al.  Corneal wound healing in monkeys 18 months after excimer laser photorefractive keratectomy . Refract Corneal Surg . 1990;6:340-345.
Alleman N, Chamon W, Silverman RH, et al.  High-frequency ultrasound quantitative analyses of corneal scarring following excimer laser keratectomy . Arch Ophthalmol . 1993;111:968-973.Article
Marshall J, Trokel SL, Rothery S, Krueger RR.  Long-term healing of the central cornea after photorefractive keratectomy using an excimer laser . Ophthalmology . 1988;95:1411-1421.Article
Taylor DM, L'Esperance FA Jr, Del Pero RA, et al.  Human excimer laser lamellar keratectomy . Ophthalmology . 1989;96:654-664.Article
Del Pero RA, Gigstad JE, Roberts AD, et al.  A refractive and histopathologic study of excimer laser keratectomy in primates . Am J Ophthalmol 1990;109:419-429.
Fantes FE, Hanna KD, Waring GO III, Pouliquen Y, Thompson KP, Savoldelli M.  Wound healing after excimer laser keratomileusis (photorefractive keratectomy) in monkeys . Arch Ophthalmol . 1990;108:665-675.Article
Malley DS, Steinert RF, Puliafito CA, Dobi ET.  Immunofluorescence study of corneal wound healing after excimer laser anterior keratectomy in the monkey eye . Arch Ophthalmol . 1990;108:1316-1322.Article
SundarRaj N, Geiss MJ III, Fantes F, et al.  Healing of excimer laser ablated monkey corneas . Arch Ophthalmol . 1990;108:1604-1610.Article
Kahle G, Städter H, Seiler T, Wollensak J.  Gas chromatographic and mass spectroscopic analysis of excimer and erbium:yttrium aluminum garnet laser-ablated human cornea . Invest Ophthalmol Vis Sci . 1992;33:2180-2184.
Vansette GB, Koch JW, Tervo K, et al.  Expression of tenascin and fibronectin in the rabbit cornea after excimer laser surgery . Graefes Arch Clin Exp Ophthalmol . 1992;230:178-183.Article
McDonald MB, Frantz JM, Klyce SD, et al.  One-year refractive results of central photorefractive keratectomy for myopia in the nonhuman primate cornea . Arch Ophthalmol . 1990;108:40-47.Article