The Effects of Epithelium-off Corneal Collagen Cross-linking on Peripheral Corneal Keratometry, Pachymetry as well as Scheimpflug Imaging Calculated Corneal Indices in Keratoconus
Adam Muzychuk, Victor Penner, Guillermo Rocha, Ahmed Al-Ghoul
Citation Information :
Muzychuk A, Penner V, Rocha G, Al-Ghoul A. The Effects of Epithelium-off Corneal Collagen Cross-linking on Peripheral Corneal Keratometry, Pachymetry as well as Scheimpflug Imaging Calculated Corneal Indices in Keratoconus. Int J Kerat Ect Cor Dis 2014; 3 (3):113-117.
To utilize Scheimpflug imaging to describe corneal changes in keratoconic patients undergoing collagen cross- linking.
Study type
Case series.
Study design
Retrospective chart review at two sites: Calgary, Alberta and Brandon, Manitoba, Canada. All patients were diagnosed with keratoconus and had undergone corneal collagen crosslinking. All patients had pre- and post-procedure imaging done with Oculus Pentacam.
Results
Sixty-one eyes of 48 patients with 6 months follow- up and 36 eyes of 27 patients with one year follow-up were included. Average age was 27 ± 12 years (15-48 years). Fifty- one males and 10 females were studied. At 1 year follow-up, all Pentacam indices were found to improve: ISV −4.44 ± 18.6 (p = 0.16), IVA −0.07 ± 0.27 (p = 0.12), KI −0.009 ± 0.082 (p = 0.49), CKI −0.012 ± 0.027 (p = 0.01), IHA −3.87 ± 23.3 (p = 0.33) and IDH −0.062 ± 0.308 (p = 0.24). Keratometry measurements were flatter at the pupil centre by 0.87 ± 2.53 D (p = 0.05). Kmax and Kmin were flatter by 0.58 ± 1.37 D (p = 0.02) and 0.33 ± 1.70 D (p = 0.25) respectively. Pupil center pachymetry was thinner by 12.9 ± 21.1 µm (p = 0.0006) at 6 months, as were the corneal apex and thinnest local by 12.9 ± 22.3 µm (p = 0.001) and 21.8 ± 54.6 µm (p = 0.05) respectively. However, all central pachymetry readings were not statistically different from baseline at the one year measurements. Peripheral corneal measurements at 6 mm diameter were no different from baseline at 6 months, however, were significantly thicker at the 1 year follow-up.
Conclusion
The data, in this study, points to a more uniform cornea post corneal collagen crosslinking. The inferior cornea becomes flatter and superior cornea steeper with less variation when comparing the corneal curvatures. The peripheral cornea becomes thicker at 1 year post-procedure. Collagen cross- linking stabilizes the cornea.
How to cite this article
Penner V, Muzychuk A, Al-Ghoul A, Rocha G. The Effects of Epithelium-off Corneal Collagen Crosslinking on Peripheral Corneal Keratometry, Pachymetry as well as Scheimpflug Imaging Calculated Corneal Indices in Keratoconus. Int J Kerat Ect Cor Dis 2014;3(3):113-117.
Transepithelial Riboflavin/Ultraviolet A Corneal Crosslinking in Keratoconus: Morphologic Studies on Human Corneas. Am J Ophthalmol 2013 Nov;156(5):874-884.
Stress-strain measurements of human and porcine corneas after riboflavin-ultraviolet- A-induced crosslinking. J Cataract Refract Surg 2003;29(9): 1780-1785.
Crosslinking treatment of progressive keratoconus: new hope. Current Opinion in Ophthalmology 2006;17(4):356-360.
, Balasubramanian D. A study of the photodynamic efficiencies of some eye lens constituents. Photochemistry and Photobiology 1991;54(1): 51-58.
Comparison of central corneal thickness measurements by rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit corneal topography. Ophthalmology 2006;113(6):937-941.
Central corneal thickness measurement with the Pentacam Scheimpflug system, optical low-coherence reflectometry pachymeter, and ultrasound pachymetry. J Cataract Refract Surg 2005;31(9):1729-1735.
Central corneal thickness measurements in unoperated eyes and eyes after PRK for myopia using Pentacam, Orbscan II, and ultrasonic pachymetry. J Refract Surg 2007;23(9):888-894.
Corneal thickness measurements in normal and keratoconic eyes: Pentacam comprehensive eye scanner versus noncontact specular microscopy and ultrasound pachymetry. J Cataract Refract Surg 2006;32(6):970-977.
Reproducibility and repeatability of central corneal thickness measurement in keratoconus using the rotating Scheimpflug camera and ultrasound pachymetry. Am J Ophthalmol 2007;144(5):712-718.
Riboflavin/ultraviolet-a- induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol 2003;135(5):620-627.
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(4):585-593.
Parasurgical therapy for keratoconus by riboflavin-ultraviolet type A rays induced crosslinking of corneal collagen: preliminary refractive results in an Italian study. J Cataract Refract Surg 2006;32(5):837-845.
Collagen crosslinking with riboflavin and ultraviolet—A light in keratoconus: long-term results. J Cataract Refract Surg 2008; 34(5):796-801.
Refractive, topographic, tomographic, and aberrometric analysis of keratoconic eyes undergoing corneal crosslinking. Ophthalmology 2009; 116(3):369-378.
Corneal collagen cross-linking for keratoconus and corneal ectasia: One-year results. J Cataract Refract Surg 2011;37(1):149-160.
Prospective longitudinal study of corneal collagen crosslinking in progressive keratoconus. Clini Experimental Ophthalmol 2013;41(6):531-536.
Scheimpflug imaging of corneas after collagen crosslinking. Cornea 2009;28(5):510-515.
Corneal topography indices after corneal collagen crosslinking for keratoconus and corneal ectasia: one-year results. J Cataract Refract Surg 2011;37(7):1282-1290.
Pentacam Indices— A Sensitive Tool to Study the Effect of Corneal Collage Crosslinking on Keratoconus. All Indian Ophthalmological Society Meeting. Kolkata, India 2010.
Corneal collagen crosslinking using riboflavin and ultraviolet—a light for keratoconus: one-year analysis using Scheimpflug imaging. J Cataract Refract Surg 2009;35(3):425-432.
Contralateral eye study of corneal collagen crosslinking with riboflavin and UVA irradiation in patients with keratoconus. J Refract Surg 2009;25(4):371-376.
Corneal collagen crosslinking with riboflavin and ultraviolet—a light for keratoconus: results in Indian eyes. Ind J Ophthalmol 2009;57(2):111-114.
Intra- operative and postoperative effects of corneal collagen crosslinking on progressive keratoconus. Archives of Ophthalmology 2009;127(10):1258-1265.
Riboflavin/Ultraviolet a corneal collagen crosslinking for the treatment of keratoconus: visual out-comes and Scheimpflug analysis. Cornea 2011;30(3):281-286.
Corneal collagen cross-linking in progressive keratoconus: multicenter results from the French National Reference Center for Keratoconus. J Cataract Refract Surg 2011;37(12):2137-2143.
Corneal collagen crosslinking: ectasia and beyond. Current Opinion in Ophthalmology 2012;23(4):280-287.
Corneal thickness changes after corneal collagen crosslinking for keratoconus and corneal ectasia: one-year results. J Cataract Refract Surg 2011;37(4):691-700.
Immunofluorescence confocal microscopy of porcine corneas following collagen crosslinking treatment with riboflavin and ultraviolet A. J Refract Surg 2008;24(7):S715-719.
Hydration behavior of porcine cornea crosslinked with riboflavin and ultraviolet A. J Cataract Refract Surg 2007;33(3):516-521.
The swelling pressure of the corneal stroma. Investigative Ophthalmol 1962;1: 158-162.
Wound healing in the rabbit cornea after corneal collagen crosslinking with riboflavin and UVA. Cornea 2007;26(5):600-605.
Corneal healing after riboflavin ultraviolet-A collagen crosslinking determined by confocal laser scanning microscopy in vivo: early and late modifications. Am J Ophthalmol 2008;146(4):527-533.
Keratocyte apoptosis after corneal collagen crosslinking using riboflavin/ UVA treatment. Cornea 2004;23(1):43-49.
Confocal microscopy identification of keratoconus associated with posterior polymorphous corneal dystrophy. J Cataract Refract Surg 2008;34(2):318-321.
Collagens and proteoglycans of the corneal extracellular matrix. Braz J Medi Biol Res 2003;36(8): 1037-1046.