Czech and Slovak Ophthalmology 399 10.31348/2025/40 Original article Metric Causes of Refractive Errors of the Eye Veselý Petr https://orcid.org/0000-0002-2195-6349 Beneš Pavel https://orcid.org/0000-0002-9430-0383 Sokolová Šidlová Jana https://orcid.org/0000-0002-3841-6541 Záděrová Petra https://orcid.org/0000-0002-3076-615X Došková Hana https://orcid.org/0000-0002-1792-9284 17 9 2025 2 4

Aims: To confirm current knowledge about the causes of refractive errors in adults. To evaluate the influence of systemic, i.e., primary curvature and, on the other hand, axial causes of refractive errors of the eye, in comparison with the Gullstrand model of the eye expressed by axial length and corneal curvature ratio. Material and Methods: The basic sample included 60 eyes of 30 subjects with an average age of 22.3 ±1.1 years. There were 3 men and 27 women in the group. They were young, generally healthy individuals, without serious eye pathologies. The basic sample was divided into research (n = 36) and control group (n = 24). We measured the axial length of the eye using the IOL MASTER 500 optical biometer (Carl Zeiss Meditec, Jena, Germany). We measured the topographic and keratometric values ​​of the cornea using the Pentacam HR device (Oculus GmbH, Wetzlar, Germany). We obtained the objective refraction values ​​by measuring them on a standard instrument automatic refractometer TRK-1P (Topcon Corp., Tokyo, Japan). We determined the axial length of the eye (AXD), the average value of keratometry (KRT) and the spherical equivalent of the refractive error (SE) as significant variables. The evaluation of variables was carried out by comparison with the Gullstrand model of the eye. Results: We calculated the ratios of the median axial length of the eye and the median keratometry in the research group with myopia (AXD/KRTM = 3.18 with IQR 0.1) and the control group (AXD/KRTK = 2.93 with IQR 0.1). The difference between the two groups was statistically significant (p < 0.001). The percentage expression of axial and curvature causes of ametropia was 72/28% in the myopic group and 83/17% in the control group. Conclusion: Our study confirmed that the AXD/KRT parameter is a significant indicator of the cause of the refractive state of the eye, with the important influence of axial length on this parameter.

 optical biometer Pentacam refractometry keratometry axial length References Naidoo KS, Leasher J, Bourne RR, et al. Global vision impairment and blindness due to uncorrected refractive error, 1990–2010. Optom Vis Sci. 2016;93(3):227-234. Harb EN, Wildsoet CF. Origins of Refractive Errors: Environmental and Genetic Factors. Annu Rev Vis Sci. 2019 Sep 15;5:47-72. Mutti DO, Mitchell GL, Jones LA, et al. Axial growth and changes in lenticular and corneal power during emmetropization in infants. Invest Ophthalmol Vis Sci. 2005;46(9):3074-3080. Kiorpes L,Wallman J. Does experimentally-induced amblyopia cause hyperopia in monkeys? Vis Res. 1995;35(9):1289-1297. Rabin J, Van Sluyters RC, Malach R. Emmetropization: a vision-dependent phenomenon. Invest Ophthalmol Vis Sci. 1981;20(4):561-564. Hashemi H, Fotouhi A, Yekta A, et al. Global and regional estimates of prevalence of refractive errors: systematic review and meta-analysis. J Curr Ophthalmol. 2018;30(1):3-22. Guggenheim JA, Zhou X, Evans DM, et al. Coordinated Genetic Scaling of the Human Eye: Shared Determination of Axial Eye Length and Corneal Curvature. Invest. Ophthalmol. Vis. Sci. 2013;54(3):1715-1721. Mei-Ju Ch, Yin-Tzu L, Chia-Chen T, al. Relationship between central corneal thickness, refractive error, corneal curvature, anterior chamber depth and axial length. Journal of the Chinese Medical Association, 2009;72(3):133-137. Vojniković B, Tamajo E. Gullstrand’s Optical Schematic System of the Eye–Modified by Vojniković & Tamajo. Collegium antropologicum, 2013;37(1): 41-45. Foo VH, Verkicharla PK, Ikram MK, et al. Axial Length/Corneal Radius of Curvature Ratio and Myopia in 3-Year-Old Children. Transl Vis Sci Technol. 2016 Feb 9;5(1):5. Demir P, Baskaran K, Theagarayan B, et al. Refractive error, axial length, environmental and hereditary factors associated with myopia in Swedish children. Clin Exp Optometry, 2021;104(5):595-601. Mutti DO, Hayes JR, Mitchell GL, et al. CLEERE Study Group. Refractive error, axial length, and relative peripheral refractive error before and after the onset of myopia. Invest Ophthalmol Vis Sci. 2007 Jun;48(6):2510-9. Dong L, Zhou WD, Hu YB, et al. Prevalence of Myopia and Axial Length Distribution in China: The Wuhu Children and Adolescents Eye Study. Invest Ophthalmol Vis Sci. 2025 Jun 2;66(6):33. Stone RA, Flitcroft DI. Ocular shape and myopia. Ann Acad Med Singap. 2004 Jan;33(1):7-15. Dogan M, Elgin U, Sen E. et al. Comparison of anterior segment parameters and axial lengths of myopic, emmetropic, and hyperopic children. Int Ophthalmol. 2019;39:335-340. Krupa P, Aldo M, Arthur H, et al. Total ocular, anterior corneal and lenticular higher order aberrations in hyperopic, myopic and emmetropic eyes, Vis Res. 2012;52(1):31-37. Zhou F, Chen N, Qian H, Gong D, Li K. A study on the variability and correlation of ocular biological measurement parameters in adult myopic patients. Front Med (Lausanne). 2025;7(11):152-163. Hashemi H, Khabazkhoob M, Miraftab M, et al. Axial length to corneal radius of curvature ratio and refractive errors. J Ophthal Vis Res. 2013 Jul;8(3):220-226. Jiang XM, Lu YY, Han X, Tan Q, Wu JS. Proportion and characteristic of emmetropia in schoolchildren aged 6-11y: the Shenzhen elementary school eye study. Int J Ophthalmol. 2020 Dec 18;13(12):1983-1989. Klein AP, Suktitipat B, Duggal P, et al. Heritability Analysis of Spherical Equivalent, Axial Length, Corneal Curvature, and Anterior Chamber Depth in the Beaver Dam Eye Study. Arch Ophthalmol. 2009;127(5):649-655. Lee SD. Comparison of the Sphere, Cylinder, Spherical Equivalent and Cylindrical Axis Between the Left and Right Eyes, IJITEE, 2019;8(8S2): 758-760.