Evaluation of Intraocular Pressure in Eyes After Femtolasik Surgery

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João Leite Bruno Ribeiro Ana Carolina Abreu Sílvia Monteiro Ana Figueiredo Rita Reis Isabel Sampaio Maria Céu Pinto Maria João Menéres


Introduction: Femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) surgery is a surgical procedure performed in the treatment of refractive errors. Given the changes in central corneal thickness, intraocular pressure may be lower and underestimated, which may lead to a late diagnosis of ocular hypertension/glaucoma.

Aims: The aim of this study was to evaluate and compare intraocular pressure, by different methods, before and after FS-LASIK, for correction of myopia or myopic astigmatism.

Methods: Retrospective and observational study, which included eyes undergoing FS-LASIK surgery (November 2020 to November 2022). The intraocular pressure values were measured (preoperatively, on the 1st, 3rd and 6th postoperative month) using contact tonometry (Goldmann applanation tonometry) and non-contact tonometry (by Corvis®ST according to the formulas: pachymetry – Ehlers, Shah, Dresden, Spoerl – and biomechanics – corrected and uncorrected). The intraocular pressure values obtained at 6 months with the different methods were compared with the Goldmann applanation tonometry intraocular pressure values obtained at baseline.

Results: Ninety patients (of a total of 174 eyes) underwent FS-LASIK, with a preoperative spherical equivalent of -3.7±1.7. Preoperatively (mean ± standard deviation) Goldmann applanation tonometry was 15.0±1.9 mmHg; the intraocular pressure values obtained through the Corvis® ST (in mmHg) according pachymetry: Ehlers (13.5±2.6), Shah (14.3±2.3), Dresden (14.5±2.2) and Spoerl (14.5±2.1); and biomechanics: corrected (14.4±1.9) and not corrected (15.3±2.1), respectively. At 6 months postoperatively, all showed statistically significant differences, with the exception of Shah's formula (p=0.074); comparing the preoperative Goldmann applanation tonometry with each of the formulas at the end of the follow-up, the Ehlers formula did not present statistically significant differences (p=0.434), the Shah formula a value of p=0.047 and the others a value of p<0.001.

Conclusion: Femtosecond laser-assisted laser in situ keratomileusis surgery underestimates intraocular pressure measurement by contact tonometry. In non-contact tonometry, at 6-month follow-up, the Shah formula appears to be less influenced by this bias. More studies are needed to evaluate the best method to assess I intraocular pressure measurement after FS-LASIK surgery.

Keywords: Intraocular pressure, Goldmann applanation tonometry, CORVIS, FemtoLASIK

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How to Cite
LEITE, João et al. Evaluation of Intraocular Pressure in Eyes After Femtolasik Surgery. Medical Research Archives, [S.l.], v. 12, n. 4, apr. 2024. ISSN 2375-1924. Available at: <https://esmed.org/MRA/mra/article/view/5346>. Date accessed: 27 may 2024. doi: https://doi.org/10.18103/mra.v12i4.5346.
Research Articles


1. Chow SC, Yeung BYM. A review on different tonometers for intraocular pressure measurement after photorefractive keratectomy or small incision lenticule extraction. Clin Ophthalmol. 2020;14:3305-3323. doi:10.2147/OPTH.S278167
2. Morgan IG, Ohno-Matsui K, Saw S-M. Myopia. Lancet. 2012;379(9827):1739-1748. doi:10.1016/S0140-6736(12)60272-4
3. Holden BA, Fricke TR, Wilson DA, et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology. 2016;123(5):1036-1042. doi:10.1016/j.ophtha.2016.01.006
4. Iglesias M, Kudsieh B, Laiseca A, et al. Intraocular pressure after myopic laser refractive surgery measured with a new Goldmann convex prism: correlations with GAT and ORA. BMC Ophthalmol. 2022;22(1):1-9. doi:10.1186/s12886-022-02309-x
5. Shousha SMA, Steit MAHA, Hosny MHM, Ewais WA, Shalaby AMM. Comparison of different intraocular pressure measurement techniques in normal eyes, post surface and post lamellar refractive surgery. Clin Ophthalmol. 2013;7(1):71-79. doi:10.2147/OPTH.S37978
6. Hemida AY, Said OM, Abdel-Meguid AAE, Iqbal M, Badawi AE. Changes in corneal biomechanics and intraocular pressure following Femto-LASIK using Goldman applanation tonometry and ocular response analyzer. Int J Ophthalmol. 2020;13(5):782-787. doi:10.18240/ijo.2020.05.13
7. Ang RET, Bargas NVR, Martinez GHA, Sosuan GMN, Nabor-Umali MI. Comparison of Three Tonometers in Measuring Intraocular Pressure in Eyes That Underwent Myopic Laser in situ Keratomileusis and Photorefractive Keratectomy. Clin Ophthalmol. 2022;16(May):1623-1637. doi:10.2147/OPTH.S362344
8. Yilmaz I, Altan C, Aygit ED, et al. Comparison of three methods of tonometry in normal subjects: Goldmann applanation tonometer, non-contact airpuff tonometer, and Tono-Pen XL. Clin Ophthalmol. 2014;8:1069-1074. doi:10.2147/OPTH.S63915
9. Montés-Micó R, Neil Charman W. Intraocular pressure after excimer laser myopic refractive surgery. Ophthalmic Physiol Opt. 2001;21(3):228-235. doi:https://doi.org/10.1046/j.1475-1313.2001.00581.x
10. Lei L, Cheng L, Xinyu L, Jieyu D. Measurement of intraocular pressure after LASIK by dynamic contour tonometry. J Huazhong Univ Sci Technol [Medical Sci. 2006;26(3):372-373. doi:10.1007/BF02829580
11. Yang Z, Miao N, Wang L, Ma K. Comparison of different correction formulas and measurement methods for the accurate determination of intraocular pressure after SMILE and FS-LASIK surgery. BMC Ophthalmol. 2022;22(1):1-8. doi:10.1186/s12886-022-02620-7
12. Cacho I, Sanchez-Naves J, Batres L, Pintor J, Carracedo G. Comparison of intraocular pressure before and after laser in situ keratomileusis refractive surgery measured with perkins tonometry, noncontact tonometry, and transpalpebral tonometry. J Ophthalmol. 2015;2015. doi:10.1155/2015/683895
13. Mardelli PG, Piebenga LW, Whitacre MM, Siegmund KD. The effect of excimer laser photorefractive keratectomy on intraocular pressure measurements using the Goldmann applanation tonometer. Ophthalmology. 1997;104(6):945-948; discussion 949. doi:10.1016/s0161-6420(97)30202-4
14. Patel S, Aslanides IM. Main causes of reduced intraocular pressure after excimer laser photorefractive keratectomy. J Refract Surg. 1996;12(6):673-674. doi:10.3928/1081-597x-19960901-04
15. Siganos DS, Papastergiou GI, Moedas C. Assessment of the Pascal dynamic contour tonometer in monitoring intraocular pressure in unoperated eyes and eyes after LASIK. J Cataract Refract Surg. 2004;30(4):746-751. doi:10.1016/j.jcrs.2003.12.033
16. Ajazaj V, Kaçaniku G, Asani M, Shabani A, Dida E. Intraocular Pressure After Corneal Refractive Surgery. Med Arch (Sarajevo, Bosnia Herzegovina). 2018;72(5):341-343. doi:10.5455/medarh.2018.72.341-343
17. Lee H, Roberts CJ, Kim T-I, Ambrósio RJ, Elsheikh A, Yong Kang DS. Changes in biomechanically corrected intraocular pressure and dynamic corneal response parameters before and after transepithelial photorefractive keratectomy and femtosecond laser-assisted laser in situ keratomileusis. J Cataract Refract Surg. 2017;43(12):1495-1503. doi:10.1016/j.jcrs.2017.08.019
18. Chen S, Lopes BT, Huang W, et al. Effectiveness of 4 tonometers in measuring IOP after femtosecond laser-assisted LASIK, SMILE, and transepithelial photorefractive keratectomy. J Cataract Refract Surg. 2020;46(7):967-974. doi:10.1097/j.jcrs.0000000000000204
19. Cai X, Qin Y, Liu S, et al. Noncontact Intraocular Pressure Measurement over Bandage Contact Lens and the Effect of Pentacam and Corvis ST’s IOP Correction System. J Ophthalmol. 2022;2022:6-11. doi:10.1155/2022/4933555
20. Joda AA, Shervin MMS, Kook D, Elsheikh A. Development and validation of a correction equation for Corvis tonometry. Comput Methods Biomech Biomed Engin. 2016;19(9):943-953. doi:10.1080/10255842.2015.1077515
21. Yanling H, Li Y, Xiaoxin L, Yiwen H. The correction of Goldmann applanation tonometer with pentacam system in measurement of IOP before and after LASIK. Chinese Ophthalmic Res. 2009;27:67-70.
22. Li H, Wang Y, Dou R, et al. [Analysis of intraocular pressure measurement and the influencing factors after small incision lenticule extraction]. Zhonghua Yan Ke Za Zhi. 2016;52(1):22-29. doi:10.3760/cma.j.issn.0412-4081.2016.01.008
23. Article O, Shafiq I. Influence of Central Corneal Thickness (CCT) on Intraocular Pressure (IOP) Measured with Goldmann Applanation Tonometer (GAT) in Normal Individuals. Published online 2008:196-200.