Corneal haze and visual outcome after collagen crosslinking for keratoconus: A comparison between total epithelium off and partial epithelial removal methods

Razmjoo, Hasan; Rahimi, Behrooz; Kharraji, Mona; Koosha, Nima; Peyman, Alireza

Corneal haze and visual outcome after collagen crosslinking for keratoconus: A comparison between total epithelium off and partial epithelial removal methods

Authors

¹ Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran

² Medical Student Research Committee, Isfahan University of Medical Sciences, Isfahan, Iran

Abstract

Background: Keratoconus is an asymmetric, bilateral, progressive noninflammatory ectasia of the cornea that affects approximately 1 in 2000 of the general population. This may cause a significant negative impact on quality of life. Corneal collagen crosslinking (CXL) is one of the recently introduced methods that have been used to decrease the progression of keratoconus, in particular, as well as other corneal-thinning processes.
Materials and Methods: A total of 44 keratoconic eyes of 22 patients were enrolled in this randomized prospective study, after obtaining informed consent. In the first group, the corneal epithelium were totally removed and in the second group, the central 3 mm of epithelium was kept intact and partial removal was performed. After collagen crosslinking in both groups, comprehensive ophthalmologic examination was performed on all patients before and 6 months after the surgery. This article is registered at www.clinicaltrial.gov with registration number NCT01809977.
Results: The difference between the two groups was not statistically significant regarding postoperative corneal haziness, refraction, and visual acuity (P > 0.05). However, comparison of pre- and postoperative parameters within each group revealed that total removal of the cornea has resulted in significant improvement of K-max (P value: 0.01) and Q-value (P value: 0.009); while eyes in partial removal group had better improvement of corrected vision (P value: 0.006). Both methods had significant and similar increase in optical corneal density (P < 0.0001).
Conclusion: In our study, keeping the central corneal epithelium intact was not beneficial for decreasing corneal haziness, however, this method caused better improvement in corrected vision. Total epithelium off technique resulted in better improvement of K-max and Q-value.

Keywords

References

1.	Coskunseven E, Jankov MR 2 ^nd , Hafezi F, Atun S, Arslan E, Kymionis GD. Effect of treatment sequence in combined intrastromal corneal rings and corneal collagen crosslinking for keratoconus. J Cataract Refract Surg 2009;35:2084-91.
2.	Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol 2003;135:620-7.
3.	Renesto Ada C, Melo LA Jr., Sartori Mde F, Campos M. Sequential topical riboflavin with or without ultraviolet a radiation with delayed intracorneal ring segment insertion for keratoconus. Am J Ophthalmol 2012;153:982-93.e3.
4.	Raiskup-Wolf F, Hoyer A, Spoerl E, Pillunat LE. Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: Long-term results. J Cataract Refract Surg 2008;34:796-801.
5.	Radner W, Zehetmayer M, Skorpik C, Mallinger R. Altered organization of collagen in the apex of keratoconus corneas. Ophthalmic Res 1998;30:327-32.
6.	Smolek MK, Beekhuis WH. Collagen fibril orientation in the human corneal stroma and its implications in keratoconus. Invest Ophthalmol Vis Sci 1997;38:1289-90.
7.	Olivares Jiménez JL, Guerrero Jurado JC, Bermudez Rodriguez FJ, Serrano Laborda D. Keratoconus: Age of onset and natural history. Optom Vis Sci 1997;74:147-51.
8.	Kymes SM, Walline JJ, Zadnik K, Gordon MO; Collaborative Longitudinal Evaluation of Keratoconus study group. Quality of life in keratoconus. Am J Ophthalmol 2004;138:527-35.
9.	Hafezi F, Kanellopoulos J, Wiltfang R, Seiler T. Corneal collagen crosslinking with riboflavin and ultraviolet A to treat induced keratectasia after laser in situ keratomileusis. J Cataract Refract Surg 2007;33:2035-40.
10.	Wollensak G, Iomdina E, Dittert DD, Herbst H. Wound healing in the rabbit cornea after corneal collagen cross-linking with riboflavin and UVA. Cornea 2007;26:600-5.
11.	Caporossi A, Baiocchi S, Mazzotta C, Traversi C, Caporossi T. Parasurgical therapy for keratoconus by riboflavin-ultraviolet type A rays induced cross-linking of corneal collagen: Preliminary refractive results in an Italian study. J Cataract Refract Surg 2006;32:837-45.
12.	Caporossi A, Mazzotta C, Baiocchi S, Caporossi T. Long-term results of riboflavin ultraviolet a corneal collagen cross-linking for keratoconus in Italy: The Siena eye cross study. Am J Ophthalmol 2010;149:585-93.
13.	Grewal DS, Brar GS, Jain R, Sood V, Singla M, Grewal SP. Corneal collagen crosslinking using riboflavin and ultraviolet-A light for keratoconus: One-year analysis using Scheimpflug imaging. J Cataract Refract Surg 2009;35:425-32.
14.	Vinciguerra P, Albè E, Trazza S, Rosetta P, Vinciguerra R, Seiler T, et al. Refractive, topographic, tomographic, and aberrometric analysis of keratoconic eyes undergoing corneal cross-linking. Ophthalmology 2009;116:369-78.
15.	Brooks NO, Greenstein S, Fry K, Hersh PS. Patient subjective visual function after corneal collagen crosslinking for keratoconus and corneal ectasia. J Cataract Refract Surg 2012;38:615-9.
16.	Shikha D, Kavita R, Sundaram N. Complications of corneal collagen cross-linking. J Ophthalmol 2011;2011:869015.
17.	Greenstein SA, Fry KL, Bhatt J, Hersh PS. Natural history of corneal haze after collagen crosslinking for keratoconus and corneal ectasia: Scheimpflug and biomicroscopic analysis. J Cataract Refract Surg 2010;36:2105-14.
18.	Jankov Li MR, Jovanovic V, Nikolic L, Lake JC, Kymionis G, Coskunseven E. Corneal collagencross-linking. Middle East Afr J Ophthalmol 2010;17:21-7.
19.	Hashemi HT, Taheri MR, Fotouhi A, Kheiltash A. Evaluation of the prophylactic use of mitomycin-C to inhibit haze formation after photorefractive keratectomy in high myopia: a prospective clinical study. BMC Ophthalmol 2004; 4: 12.
20.	Greenstein SA, Fry KL, Hersh PS. Corneal topography indices after corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results. J Cataract Refract Surg 2011;37:1282-90.
21.	Pouliquen Y. Doyne lecture keratoconus. Eye (Lond) 1987;1:1-14.
22.	Raiskup-Wolf F, Hoyer A, Spoerl E, Pillunat LE. Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: Long-term results. J Cataract Refract Surg 2008;34:796-801.
23.	Greenstein SA, Fry KL, Hersh MJ, Hersh PS. Higher-order aberrations after corneal collagen crosslinking for keratoconus and corneal ectasia. J Cataract Refract Surg 2012;38:292-302.
24.	Greenstein SA, Fry KL, Hersh PS. Effect of topographic cone location on outcomes of corneal collagen cross-linking for keratoconus and corneal ectasia. J Refract Surg 2012;28:397-405.
25.	Vinciguerra P, Camesasca FI, Albè E, Trazza S. Corneal collagen cross-linking for ectasia after excimer laser refractive surgery: 1-year results. J Refract Surg 2010;26:486-97.
26.	Ahearne M, Yang Y, Then KY, Liu KK. Non-destructive mechanical characterisation of UVA/riboflavin crosslinked collagen hydrogels. Br J Ophthalmol 2008;92:268-71.
27.	Wollensak G, Spoerl E, Wilsch M, Seiler T. Endothelial cell damage after riboflavin-ultraviolet-A treatment in the rabbit. J Cataract Refract Surg 2003;29:1786-90.
28.	Mazzotta C, Balestrazzi A, Baiocchi S, Traversi C, Caporossi A. Stromal haze after combined riboflavin-UVA corneal collagen cross-linking in keratoconus: In vivo confocal microscopic evaluation. Clin Experiment Ophthalmol 2007;35:580-2.
29.	Koller T, Mrochen M, Seiler T. Complication and failure rates after corneal crosslinking. J Cataract Refract Surg 2009;35:1358-62.
30.	Hanna KD, Pouliquen YM, Waring GO 3 ^rd , Savoldelli M, Fantes F, Thompson KP. Corneal wound healing in monkeys after repeated excimer laser photorefractive keratectomy. Arch Ophthalmol 1992;110:1286-91.
31.	Carr JD, Patel R, Hersh PS. Management of late corneal haze following photorefractive keratectomy. J Refract Surg 1995;11:S309-13.
32.	Nakamura K, Kurosaka D, Bissen-Miyajima H, Tsubota K. Intact corneal epithelium is essential for the prevention of stromal haze after laser assisted in situ keratomileusis. Br J Ophthalmol 2001; 85:209-13.
33.	Hersh PS, Greenstein SA, Fry KL. Corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results. J Cataract Refract Surg 2011;37:149-60.
34.	Fan ZJ, Xu SJ, Jia ZH, Liu BC. Clinical significance of corneal Q value in myopia patients. Int J Ophthalmol 2006;6:642-3.
35.	Koller T, Iseli HP, Hafezi F, Vinciguerra P, Seiler T. Scheimpflug imaging of corneas after collagen cross-linking. Cornea 2009;28:510-5.
36.	Lim LS, Beuerman R, Lim L, Tan DT. Late-onset deep stromal scarring after riboflavin-UV-A corneal collagen cross-linking for mild keratoconus. Arch Ophthalmol 2011;129:360-2.
37.	Greenstein SA, Shah VP, Fry KL, Hersh PS. Corneal thickness changes after corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results. J Cataract Refract Surg 2011;37:691-700.
38.	Shaw AJ, Collins MJ, Davis BA, Carney LG. Corneal refractive changes due to short-term eyelid pressure in downward gaze. J Cataract Refract Surg 2008;34:1546-53.
39.	Swartz T, Marten L, Wang M. Measuring the cornea: The latest developments in corneal topography. Curr Opin Ophthalmol 2007;18:325-33.
40.	Raiskup F, Hoyer A, Spoerl E. Permanent corneal haze after riboflavin-UVA-induced cross-linking in keratoconus. J Refract Surg 2009;25:S824-8.

Advanced Biomedical Research