Morphometric Analysis of Corneal Nerves Condition after Laser Keratorefractive Surgery

Purpose: to conduct a morphometric assessment of the corneal nerves state after laser keratorefractive surgery using laser confocal microscopy and the software Liner 1.2S. Patients and methods. 40 eyes of 20 patients received LASIK to correct a mean refractive error of –4.5 ± 1.9 diopters (range, –2.25 to –8.25 diopters). The stroma was ablated with a Teneo Technolas 317P excimer laser. Corneas were examined by laser corneal confocal microscopy (HRT III with Rostock Cornea Module) before and in 1, 3, and 6 months after LASIK. Images were analyzed with software that automatically computes coefficients of anisotropy and orientation symmetry of corneal nerves. Result. At 1 and 3 months after surgery, the center corneal nerves were completely absent. At 1, 3 and 6 months after surgery, the paracentral corneal nerves were detected and the coefficient of anisotropy were statistically significantly reduced compared with the preoperative rates. At 6 months after surgery, both central and peripheral corneal nerves were detected and the coefficient of anisotropy were statistically significantly reduced compared with the preoperative rates. Conclusion. As a result of the study, the central corneal nerves were first detected at 6 months after surgery, whereas the paracentral cornea nerves were detected already after 1 month. At 6 months after surgery, the coefficient of anisotropy in the central of cornea statistically significant decreased compared to the preoperative rates. At all stages of the study after surgery, the anisotropy coefficient in the cornea paracentral statistically significant decreased compared with preoperative.

1. Lee B.H., McLaren J.W., Erie J.C. Reinnervation in the cornea after LASIK. Invest Ophthalmol Vis Sci. 2002;43:3660–3664.

2. Calvillo M.P., McLaren J.W., Hodge D.O., Bourne W.M. Corneal reinnervation after LASIK: prospective 3-year longitudinal study. Invest Ophthalmol Vis Sci. 2004;45:3991–3996.

3. Erie J.С. Corneal wound healing after photorefractive keratectomy: a 3-year confocal microscopy study. Trans Am OphthalmolSoc. 2003;101:293–333.

4. Erie J.С., McLaren J.W., Hodge D.O., Bourne W.M. Recovery of corneal subbasal nerve density after PRK and LASIK. Am J Ophthalmol. 2005;140(6):1059–1064. DOI: 10.1016/j.ajo.2005.07.027

5. Darwish T., Brahma A., O’Donnell C., Efron N. Subbasal nerve fiber regeneration after LASIK and LASEK assessed by noncontact esthesiometry and in vivo confocal microscopy: prospective study. J Cataract Refract Surg. 2007;33(9):1515–1521. DOI: 10.1016/j.jcrs.2007.05.023

6. Lee S.J., Kim J.K., Seo K.Y. Comparison of corneal nerve regeneration and sensitivity between LASIK and laser epithelial keratomileusis (LASEK) Am J Ophthalmol. 2006;141:1009–1015. DOI: 10.1016/j.ajo.2006.01.048

7. Patel S.V., McLaren J.W., Kittleson B.S., Bourne W.M. Subbasal nerve density and corneal sensitivity after LASIK: femtosecond laser vs mechanical microkeratome. Arch Ophthalmol. 2010;128(11):1413–1419. DOI: 10.1001/archophthalmol.2010.253

8. Tkachenko N.V. Astakhov S.Yu. Confocal microscopy diagnostic abilities in investigation of superficial eyeball structures. Ophthalmology journal = Oftal’mologicheskie vedomosti. 2009;2 (1):82–89 (In Russ.)

9. Surnina Z.V. Opportunities for confocal and laser biomicroscopy of corneal nerves in diabetic polyneuropathy. Annals of Ophthalmology = Vestnik oftal’mologii 2015;131(1):104–108 (In Russ.) DOI: 10.17116/oftalma20151311104-108

10. Hu L., Xie W., Liu J., Zhou Y., Zhou Q., Yu Y., Chen J., Lu F. Tear menisci and corneal subbasal nerve density in patients after laser in situ keratomileusis. Eye Contact Lens. 2015;41(1):51–57. DOI: 10.1097/ICL.0000000000000062

11. Kowtharapu B.S., Winter K., Marfurt C., Allgeier S., Köhler B., Hovakimyan M., Stahnke T., Wree A., Stachs O., Guthoff R.F. Comparative quantitative assessment of the human corneal sub-basal nerve plexus by in vivo confocal microscopy and histological staining. Eye (Lond). 2017;31(3):481–490. DOI: 10.1038/eye.2016.220

12. Avetisov S.E, Novikov I.A, Makhotin S.S, Surnina Z.V. New approach to corneal nerve fibers morphometry in diabetes mellitus on the basis of confocal biomicroscopy. Annals of Ophthalmology = Vestnik oftal’mologii. 2015;131(4):5–14 (In Russ.) DOI: 10.17116/oftalma201513145-14

13. Kauffmann T., Bodanowitz S., Hesse L., Kroll P. Corneal reinnervation after photorefractive keratectomy and laser in situ keratomileusis: an in vivo study with a confocal videomicroscope. Ger J Ophthalmol. 1996;5(6):508–512.

14. Linna T.U., Vesaluoma M.H., Perez-Santonja J.J., et al. Effect of myopic LASIK on corneal sensitivity and morphology of subbasal nerves. Invest Ophthalmol Vis Sci 2000;41(2):393–397.

15. Hu L., Xie W., Liu J., Zhou Y., Zhou Q., Yu Y., Chen J., Lu F. Tear menisci and corneal subbasal nerve density in patients after laser in situ keratomileusis. Eye Contact Lens 2015;41(1):51–57. DOI: 10.1097/ICL.0000000000000062

16. Deng S., Mengmeng Wang, Fengju Zhang, Xuguang Sun, Wenbo Hou, Ning Guo Corneal subbasal nerve fiber regeneration in myopic patients after laser in situ keratomileusis. Neural Regen Res. 2012;7(20): 1556–1562. DOI: 10.3969/j.issn.1673-5374.2012.20.005