The results of excimer laser PRK are promising as more than 80% of eyes with up to −6.0 diopters of attempted correction have refractive results within 1.0 diopter of emmetropia. However, throughout the dioptric range some unexpected results have been observed with individual patients showing an aggressive wound healing response with excessive myopic regression and severe corneal haze. Unfortunately, only limited data are available about the cellular and extracellular responses in human corneas after PRK and this information is important to establish adequate postoperative pharmaceutical treatment.
Methods.
We made a histopathological and immunohistochemical study on 20 human corneal samples from patients with severe corneal haze and myopic regression. The indirect immunofluorescence method was used for demonstration of collagen types I, III, IV laminin, chondroitin sulphate, dermatan sulphate, and keratin.
Results.
All corneal specimens showed a hyperplastic epithelium. Histologically, most samples (16/20) showed mainly a loose lamination of extracellular material which could be identified as collagen type IV. The remaining four samples had newly synthesised collagen type III.
Conclusions
Our histopathological results indicate that corneal wound healing after excimer laser PRK varies among individuals. In some people epithelial basement proteins, such as collagen type IV, are the main wound healing products, whereas in others mainly collagen type III is found postoperatively, which does not effect the synthesis of collagen type IV. This suggests the need for individually-tailored postoperative pharmaceutical treatment regimens.
GartryD.S., Kerr MuirM., MarshallJ.Photorefractive keratectomy with an argon fluoride excimer laser: a clinical study.J Refract Corneal Surg1991; 7: 420–35.
2.
SeilerT., WollensakJ.Myopic photorefractive keratectomy with the excimer laser. One year follow-up.Ophthalmology1991; 98: 1156–63.
3.
McDonaldM.B., LiuJ.C., ByrdT.J.. Central photorefractive keratectomy for myopia: partially sighted and normal sighted eyes.Ophthalmology1991; 98: 1327–37.
4.
SherN.A., ChenV., BowersR.A.. The use of the 193 nm excimer laser for myopic photorefractive keratectomy in sighted eyes: a multicenter study.Arch Ophthalmol1991; 109: 1525–30.
5.
SalzJ.J., MaguenE., NesburnA.B.. A two-year experience with the excimer laser photorefractive keratectomy for myopia.Ophthalmology1993; 100: 873–82.
6.
TengrothB., EpsteinD., FagerholmP., Hamberg-NystromH., FitzsimmonsT.D.Excimer laser photorefractive keratectomy for myopia. Clinical results in sighted eyes.Ophthalmology1993; 100: 739–45.
HeitzmannJ., BinderP.S., KassarB.S., NordanL.T.The correction of high myopia using the excimer laser.Arch Ophthalmol1993; 111: 1627–34.
9.
DitzenK., AnschützT., SchröderE.Photorefractive keratectomy to treat low, medium and high myopia: a multicenter study.J Cataract Refract Surg1994; 20: 234–8.
10.
RogersC.M., LawlessM.A., CohenP.R.Photorefractive keratectomy for myopia more than −10 diopters.J Refract Corneal Surg1994; 10: S171–3.
11.
CarsonC.A., TaylorH.R.Excimer laser treatment of high and extreme myopia.Arch Ophthalmol1995; 113: 431–6.
12.
KruegerR.R., TalamoJ.H., McDonaldM.B., VarnellR.J., WagonerM.D., McDonnellP.J.Clinical analysis of excimer laser photorefractive keratectomy using a multiple zone technique for severe myopia.Am J Ophthalmol1995; 119: 263–74.
13.
TaylorH.R., McCartyC.A., AldredG.F.Predictability of excimer laser treatment of myopia.Arch Ophthalmol1996; 114: 248–51.
14.
McCartyC.A., AldredG.F., TaylorH.R.Comparison of results of excimer laser correction of all degrees of myopia at 12 months postoperatively.Am J Ophthalmol1996; 121: 372–83.
15.
LohmannC., GartryD., Kerr MuirM., TimberlakeG., FitzkeF., MarshallJ.“Haze” in photorefractive keratectomy: its origins and consequences.Lasers & Light Ophthalmol1991; 4: 15–34.
16.
MunnerlynC.R., KoonsS.J., MarshallJ.Photorefractive keratectomy: a technique for laser refractive surgery.J Cataract Refract Surg1988; 14: 46–52.
17.
GasterR.N., BinderP., Goalwell. Corneal surface ablation by 193 nm excimer laser and wound healing in rabbits.Invest Ophthalmol Vis Sci1989; 30: 90–7.
18.
MarshallJ., TrokelS., RotheryS., KruegerR.R.Long-term healing of the central cornea after photorefractive keratectomy using an excimer laser.Ophthlmology1988; 95: 1411–21.
19.
HannaK.D., PouliquenY.M., SalvodelliM.. Corneal wound healing in monkeys 18 months after excimer laser photorefractive keratectomy.Refract Corneal Surg1990; 6: 340–5.
20.
TuftS., ZabelR.W., MarshallJ., Corneal repair following keratectomy: a comparison between conventional surgery and laser photoablation.Invest Ophthalmol Vis Sci1989; 30: 1767–77.
21.
TuftS., MarshallJ., RotheryS.Stromal remodelling following photorefractive keratectomy.Lasers Ophthalmol1987; 1: 177–85.
22.
MarshallJ., TrokelS., RotheryS., KruegerR.R.Photoablative reprofiling of the cornea using an excimer laser: photorefractive keratectomy.Lasers Ophthalmol1986; 1: 21–48.
23.
Sundar RajN., GeissM.J., FantesF.. Healing of excimer laser ablated monkey corneas: an immunohistochemical evaluation.Arch Ophthalmol1990; 108: 1604–10.
GipsonI.K., Spurr-MichaudS.J., TsidaleA.S.Anchoring fibrils from a complex network in human and rabbit cornea.Invest Ophthalmol Vis Sci1987; 28: 212–20.
26.
OhjiM., Sundar RajN., HassellJ.R.. Basement membrane synthesis by human corneal epithelial cells in vitro.Invest Ophthalmol Vis Sci1994; 35: 479–85.
NewsomeD.A., RoidartJ.M., HassellJ.R.. Detection of specific collagen types in normal and keratoconus corneas.Invest Ophthalmol Vis Sci1981; 22: 720–38.
29.
MarshallG.E., KontasA.G., LeeW.R.Immunogold fine structural localisation of extracellular matrix components in aged human corneas. I. types l-IV collagen and laminin.Graefes Arch Clin Exp Ophthalmol1991; 229: 157–64.
30.
MarshallG.E., KontasA.G., LeeW.R.Immunogold fine structural localisation of extracellular matrix components in aged human corneas. II. types V-VI collagen.Graefes Arch Clin Exp Ophthalmol1991; 229: 164–71.
31.
MarshallG.E., KontasA.G.P., LeeW.R.Collagens in ocular tissues.Br J Ophthalmol1993; 77: 515–24.
32.
HassellJ.R., SchrecengostP.K., RadaJ.A.. Biosynthesis of stromal matrix proteoglycans and basement membrane components by human corneal fibroblasts.Invest Ophthalmol Vis Sci1992; 33: 547–57.
33.
FunderburghJ.L., ChandlerJ.W.Proteoglycans of rabbit corneas with non-perforating wounds.Invest Ophthalmol Vis Sci1989; 30: 435–42.
34.
CintronC., CovingtonH.I., KublinC.L.Morphologic analysis of proteoglycans in rabbit corneal scars.Invest Ophthalmol Vis Sci1990; 31: 1789–98.
35.
MarshallJ., TrokelS., RotheryS., SchubertH.An ultrastructural study of corneal incisions induced by an excimer laser at 193 nm.Ophthalmology1985; 92: 749–58.
36.
Del PeroR.A., GigstadJ.E., RobertsA.D.. A refractive and histopathological study of excimer laser keratectomy in primates.Arch Ophthalmol1990; 109: 419–29.
37.
FantesE.F., HannaK.D., WaringG.O.. Wound healing after excimer laser keratomileusis (photorefractive keratectomy) in monkeys.Arch Ophthalmol1990; 108: 665–75.
38.
MalleyD.S., SteinertR.F., PuliafitoC.A., DobiE.T.Immunofluorescence study of corneal wound healing after excimer laser anterior keratectomy in the monkey eye.Arch Ophthalmol1990; 108: 1316–22.
39.
RaweI.M., ZabelR.W., TuftS.J., ChenV., MeekK.M.A morphological study of rabbit corneal wound healing after laser keratectomy.Eye1992; 6: 637–42.
40.
HannaK.D., PouliquenY., WaringG.O.. Corneal stromal wound healing in rabbits after 193 nm excimer laser surface ablation.Arch Ophthalmol1989; 107: 895–901.
41.
HassellJ.R., CintronC., Kublin. Proteoglycan changes during restoration of transparency in corneal scars.Arch Biochem Biophys1983; 222: 262–8.
42.
FitzsimmonsT.D., FagerholmP., HärfstrandA., SchenholmM.Hyaluronic acid in the rabbit cornea after excimer laser superficial keratectomy.Invest Ophthalmol Vis Sci1992; 33: 3011–6.
43.
FagerholmP., Hamberg-NyströmH., TengrothB.Wound healing and myopic regression following photorefractive keratectomy.Acta Ophthalmologica1994; 72: 229–34.
44.
BinderP.S., WicckhamM.G., SavalaE.Y.. Corneal anatomy and wound healing. In: Symposium on medical and surgical diseases of the cornea. Transactions of the New Orleans Academy of Ophthalmology.St Louis: CV Mosby Co1980; 1–35.
45.
MauriceD.M.The cornea and sclera. In: DavsonH., ed. The eye, 3rd edition.London: Academic Press, 1984.
46.
BenedekG.B.Theory of transparency of the eye.Appl Opt1971; 10: 459–73.
47.
TengrothB., FagerholmP., SoderbergP., Hamberg-NyströmH., EpsteinD.Effect of corticosteroids in postoperative care following photorefractive keratectomies.Refract Corneal Surg1993; 9(suppl): S61–4.
48.
CaronesF., BrancatoR., VenturiE., ScialdoneA., BertuzziA., TavolaA.Efficacy of corticosteroids in reversing regression after myopic photorefractive keratectomy.Refract Corneal Surg1993; 9(suppl): S52–4.
49.
GartryD.S., Kerr MuirM., LohmannC., MarshallJ.The effect of topical corticosteroids on refractive outcome and corneal haze after photorefractive keratectomy.Arch Ophthalmol1992; 110: 944–52.
50.
O'BrartD.P.S., LohmannC., KlonosG., CorbettM., Kerr MuirM., MarshallJ.The effects of topical corticosteroids and plasmin inhibitors on refractive outcome, haze, and visual performance after photorefractive keratectomy.A prospective, randomized, observer-masked study’ Ophthalmology1994; 101: 1565–74.
51.
PrinceJ.H.The rabbit eye related to that of man. In: The rabbit in eye research.Springfield: Charles C Thomas, 1964; 9–14.
52.
BaileyA.J.Collagen and elastin fibres.J Clin Pathol1978; 12(suppl): S49–58.
