Abstract
Background
The purpose of this study was to compare corneal subbasal nerve morphology, corneal sensation, and tear film parameters after femtosecond lenticule extraction (FLEX) and small-incision lenticule extraction (SMILE).
Methods
A prospective, randomized, single-masked, paired-eye design clinical trial of 35 patients treated for moderate to high myopia with FLEX in one eye and SMILE in the other. In both techniques, an intrastromal lenticule was cut by a femtosecond laser and manually extracted. In FLEX, a LASIK-like flap allowed removal of the lenticule, whereas in SMILE, it was removed through a small incision. In-vivo confocal microscopy was used to acquire images of the central corneal subbasal nerve plexus, from which nerve density, total nerve number, and nerve tortuosity were analyzed. Corneal sensation was measured using Cochet–Bonnet esthesiometry. A visual analog scale, tear osmolarity, non-invasive tear film break-up time (keratograph) tear meniscus height (anterior segment OCT), Schirmer's test, and fluorescein tear film break-up time were used to evaluate tear film and ocular surface symptoms. Patients were examined before and 6 months after surgery.
Results
There were no statistically significant differences in baseline parameters between FLEX and SMILE (p > 0.050). With regard to changes from before to 6 months after surgery, mean reduction in subbasal nerve density was 14.22 ± 6.24 mm/mm2 in FLEX eyes, and 9.21 ± 7.80 mm/mm2 in SMILE eyes (p < 0.05). The total number of nerves decreased more in FLEX eyes than in SMILE eyes (p < 0.05). No change was found when comparing tortuosity (p > 0.05). Corneal sensation was reduced with 0.38 ± 0.49 cm in FLEX eyes, and 0.10 ± 0.34 cm in SMILE eyes (p < 0.01). No differences were found between FLEX and SMILE in tear film evaluation tests (p > 0.05). Significantly more patients felt postoperative foreign body sensation in the FLEX eye within the first days after surgery, as compared to the SMILE eye.
Conclusions
Six months after surgery, the less invasive SMILE technique seemed better at sparing the central corneal nerves as compared to FLEX. Corneal sensation was only significantly reduced in FLEX eyes. There were no differences between FLEX and SMILE when comparing tear film evaluation tests 6 months after surgery.
Similar content being viewed by others
References
Ratkay-Traub I, Juhasz T, Horvath C, Suarez C, Kiss K, Ferincz I, Kurtz R (2001) Ultra-short pulse (femtosecond) laser surgery: initial use in LASIK flap creation. Ophthalmol Clin N Am 14:347–355, viii–ix
Sekundo W, Kunert K, Russmann C, Gille A, Bissmann W, Stobrawa G, Sticker M, Bischoff M, Blum M (2008) First efficacy and safety study of femtosecond lenticule extraction for the correction of myopia: six-month results. J Cataract Refract Surg 34:1513–1520
Blum M, Kunert K, Schroder M, Sekundo W (2010) Femtosecond lenticule extraction for the correction of myopia: preliminary 6-month results. Graefes Arch Clin Exp Ophthalmol 248:1019–1027
Blum M, Sekundo W (2010) Femtosecond lenticule extraction (FLEx). Ophthalmologe 107:967–970
Vestergaard A, Ivarsen A, Asp S, Hjortdal JO (2012) Femtosecond (FS) laser vision correction procedure for moderate to high myopia: a prospective study of ReLEx(®) flex and comparison with a retrospective study of FS-laser in situ keratomileusis. Acta Ophthalmol 91(4):355–362. doi:10.1111/j.1755-3768.2012.02406.x
Sekundo W, Kunert KS, Blum M (2011) Small incision corneal refractive surgery using the small incision lenticule extraction (SMILE) procedure for the correction of myopia and myopic astigmatism: results of a 6 month prospective study. Br J Ophthalmol 95:335–339
Shah R, Shah S, Sengupta S (2011) Results of small incision lenticule extraction: all-in-one femtosecond laser refractive surgery. J Cataract Refract Surg 37:127–137
Vestergaard A, Ivarsen AR, Asp S, Hjortdal JO (2012) Small-incision lenticule extraction for moderate to high myopia: predictability, safety, and patient satisfaction. J Cataract Refract Surg 38:2003–2010
Hjortdal JO, Vestergaard AH, Ivarsen A, Ragunathan S, Asp S (2012) Predictors for the outcome of small-incision lenticule extraction for myopia. J Refract Surg 28:865–871
Wei S, Wang Y (2013) Comparison of corneal sensitivity between FS-LASIK and femtosecond lenticule extraction (ReLEx flex) or small-incision lenticule extraction (ReLEx smile) for myopic eyes. Graefes Arch Clin Exp Ophthalmol 251(6):1645–1654. doi:10.1007/s00417-013-2272-0
Tavakoli M, Kallinikos P, Iqbal A, Herbert A, Fadavi H, Efron N, Boulton AJ, Malik RA (2011) Corneal confocal microscopy detects improvement in corneal nerve morphology with an improvement in risk factors for diabetic neuropathy. Diabet Med 28:1261–1267
Pritchard N, Edwards K, Vagenas D, Russell AW, Malik RA, Efron N (2012) Corneal sensitivity is related to established measures of diabetic peripheral neuropathy. Clin Exp Optom 95:355–361
Labbe A, Alalwani H, Van Went C, Brasnu E, Georgescu D, Baudouin C (2012) The relationship between subbasal nerve morphology and corneal sensation in ocular surface disease. Invest Ophthalmol Vis Sci 53:4926–4931
Oliveira-Soto L, Efron N (2001) Morphology of corneal nerves using confocal microscopy. Cornea 20:374–384
Cruzat A, Pavan-Langston D, Hamrah P (2010) In vivo confocal microscopy of corneal nerves: analysis and clinical correlation. Semin Ophthalmol 25:171–177
Meijering E (2010) Neuron tracing in perspective. Cytometry Part A 77:693–704
Lee SJ, Kim JK, Seo KY, Kim EK, Lee HK (2006) Comparison of corneal nerve regeneration and sensitivity between LASIK and laser epithelial keratomileusis (LASEK). Am J Ophthalmol 141:1009–1015
Erie JC, McLaren JW, Hodge DO, Bourne WM (2005) Recovery of corneal subbasal nerve density after PRK and LASIK. Am J Ophthalmol 140:1059–1064
Niederer RL, Perumal D, Sherwin T, McGhee CN (2007) Corneal innervation and cellular changes after corneal transplantation: an in vivo confocal microscopy study. Invest Ophthalmol Vis Sci 48:621–626
Feng YF, Yu JG, Wang DD, Li JH, Huang JH, Shi JL, Ye T, Wang QM, Zhao YE (2013) The effect of hinge location on corneal sensation and dry eye after LASIK: a systematic review and meta-analysis. Graefes Arch Clin Exp Ophthalmol 251:357–366
Kumano Y, Matsui H, Zushi I, Mawatari A, Matsui T, Nishida T, Miyazaki M (2003) Recovery of corneal sensation after myopic correction by laser in situ keratomileusis with a nasal or superior hinge. J Cataract Refract Surg 29:757–761
Perez-Gomez I, Efron N (2003) Change to corneal morphology after refractive surgery (myopic laser in situ keratomileusis) as viewed with a confocal microscope. Optom Vis Sci 80:690–697
Hosal BM, Ornek N, Zilelioglu G, Elhan AH (2005) Morphology of corneal nerves and corneal sensation in dry eye: a preliminary study. Eye (Lond) 19:1276–1279
Benitez-Del-Castillo JM, Acosta MC, Wassfi MA, Diaz-Valle D, Gegundez JA, Fernandez C, Garcia-Sanchez J (2007) Relation between corneal innervation with confocal microscopy and corneal sensitivity with noncontact esthesiometry in patients with dry eye. Invest Ophthalmol Vis Sci 48:173–181
Levinson BA, Rapuano CJ, Cohen EJ, Hammersmith KM, Ayres BD, Laibson PR (2008) Referrals to the Wills Eye Institute Cornea Service after laser in situ keratomileusis: reasons for patient dissatisfaction. J Cataract Refract Surg 34:32–39
Golas L, Manche EE (2011) Dry eye after laser in situ keratomileusis with femtosecond laser and mechanical keratome. J Cataract Refract Surg 37:1476–1480
Murakami Y, Manche EE (2012) Prospective, randomized comparison of self-reported postoperative dry eye and visual fluctuation in LASIK and photorefractive keratectomy. Ophthalmology 119:2220–2224
Pflugfelder SC, Solomon A, Stern ME (2000) The diagnosis and management of dry eye: a twenty-five-year review. Cornea 19:644–649
Mian SI, Li AY, Dutta S, Musch DC, Shtein RM (2009) Dry eyes and corneal sensation after laser in situ keratomileusis with femtosecond laser flap creation. Effect of hinge position, hinge angle, and flap thickness. J Cataract Refract Surg 35:2092–2098
Hong J, Sun X, Wei A, Cui X, Li Y, Qian T, Wang W, Xu J (2013) Assessment of tear film stability in dry eye with a newly developed keratograph. Cornea 32(5):716–721. doi:10.1097/ICO.0b013e3182714425
Nichols KK, Nichols JJ, Mitchell GL (2004) The lack of association between signs and symptoms in patients with dry eye disease. Cornea 23:762–770
Johnson ME (2009) The association between symptoms of discomfort and signs in dry eye. Ocular Surf 7:199–211
Sullivan BD, Crews LA, Messmer EM, Foulks GN, Nichols KK, Baenninger P, Geerling G, Figueiredo F, Lemp MA (2012) Correlations between commonly used objective signs and symptoms for the diagnosis of dry eye disease: clinical implications. Acta Ophthalmol Dec 28 [Epub ahead of print]. doi:10.1111/aos.12012
Sullivan BD, Crews LA, Sonmez B, de la Paz MF, Comert E, Charoenrook V, de Araujo AL, Pepose JS, Berg MS, Kosheleff VP, Lemp MA (2012) Clinical utility of objective tests for dry eye disease: variability over time and implications for clinical trials and disease management. Cornea 31:1000–1008
Best N, Drury L, Wolffsohn JS (2012) Clinical evaluation of the Oculus Keratograph. Contact Lens Anterior Eye : J Br Contact Lens Assoc 35:171–174
Wang HF, Fukuda M, Shimomura Y (2005) Diagnosis of dry eye. Semin Ophthalmol 20:53–62
Wang J, Palakuru JR, Aquavella JV (2008) Correlations among upper and lower tear menisci, noninvasive tear break-up time, and the Schirmer test. Am J Ophthalmol 145:795–800
Ibrahim OM, Dogru M, Takano Y, Satake Y, Wakamatsu TH, Fukagawa K, Tsubota K, Fujishima H (2010) Application of visante optical coherence tomography tear meniscus height measurement in the diagnosis of dry eye disease. Ophthalmology 117:1923–1929
Fukuda R, Usui T, Miyai T, Yamagami S, Amano S (2013) Tear meniscus evaluation by anterior segment swept-source optical coherence tomography. Am J Ophthalmol 155(4):620–624, 624.e1-e2. doi:10.1016/j.ajo.2012.11.009
Vagenas D, Pritchard N, Edwards K, Shahidi AM, Sampson GP, Russell AW, Malik RA, Efron N (2012) Optimal image sample size for corneal nerve morphometry. Optom Vis Sci 89:812–817
Acknowledgements
This study was only made possible due to financial support provided by: Odense University Hospitals PhD Research Grant, Danish Eye Health Society, (Fight for Sight, Denmark) Bagenkop Nielsens Myopia-Foundation, The Synoptik Foundation, The A. P. Møller Foundation for the Advancement of Medical Science, The Danish Society of Ophthalmology, Institute of Clinical Research at the University of Southern Denmark, The A. J. Andersen and Wife Foundation, The Hans and Nora Buchard Foundation, The Henry and Astrid Møller Foundation, University of Southern Denmark.
Pentacam HR and Heidelberg Spectralis OCT with anterior segment module was donated by Bagenkop Nielsens Myopia-Foundation.
Financial support
Hjortdal J.: Travel reimbursement. Other authors: None.
Author information
Authors and Affiliations
Corresponding author
Additional information
Clinical Trials registration reference number: NCT01673503, at www.clinicaltrials.gov
The authors have full control of all primary data, and agree to allow Graefe's Archive for Clinical and Experimental Ophthalmology to review their data upon request.
Rights and permissions
About this article
Cite this article
Vestergaard, A.H., Grønbech, K.T., Grauslund, J. et al. Subbasal nerve morphology, corneal sensation, and tear film evaluation after refractive femtosecond laser lenticule extraction. Graefes Arch Clin Exp Ophthalmol 251, 2591–2600 (2013). https://doi.org/10.1007/s00417-013-2400-x
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00417-013-2400-x