Objective criteria of the axial and refractive components in the modified classification for distinguishing among axial, refractive, mixed and combinatory myopias proposed based on the analysis of morphometric parameters of myopic and emmetropic eyes
O.V. Maliieva, N.M. Bushuieva
SI "The Filatov Institute of Eye Diseases and Tissue Therapy of the NAMS of Ukraine; Odesa (Ukraine)
TO CITE THIS ARTICLE: Maliieva OV, Bushuieva NM. Objective criteria of the axial and refractive components in the modified classification for distinguishing among axial, refractive, mixed and combinatory myopias proposed based on the analysis of morphometric parameters of myopic and emmetropic eyes. J.ophthalmol.(Ukraine).2020;6:10-6. http://doi.org/10.31288/oftalmolzh202111016
Background: Myopia is heterogeneous with regard to its origin and varies in its course and prognosis of sequelae. The lack of criteria does not allow in practice to distinguish among different types of the disease.
Purpose: First, to study morphometric parameters characterizing the axial and refractive components (the axial length (AL) and corneal refractive power (CRP)) in myopes and emmetropes, and; second, to develop the criteria for selecting the ranges for axial, refractive, mixed and combinatory myopias based on the statistical analysis of AL and CRP.
Material and Methods: Two hundred and sixty four patients (502 eyes) with various severities of myopia (mean myopic refractive error, –2.74 ± 2.41 D) and 78 emmetropes (145 eyes) were included in the study. Patients underwent visual acuity assessment for distance; autokeratorefractometry; measurement of horizontal pupil diameter and horizontal corneal diameter; ultrasonography of the posterior and anterior segments of the eye for AL, anterior chamber depth, and lens thickness measurements and pachymetry; and uncorrected intraocular pressure (IOP) and IOP corrected for pachymetry measurements.
Results: The objective limits for different types of myopia were calculated based on the axial component (AL, 24.3 mm) and refractive component (CRP, 43.86 D). The newly developed objective criteria allow for establishing the type of myopia corresponding to axial and refractive components on the basis of corneal refractive power and axial length of the eye. The proposed modified classification of the types of myopia takes in account the axial and refractive components and allows for distinguishing practically among refractive myopia (AL ≤ 24.3 mm and CRP > 43.86 D), axial myopia (AL > 24.3 mm and CRP ≤ 43.86 D), mixed myopia (AL > 24.3 mm and CRP > 43.86 D), and combinatory myopia (AL ≤ 24.3 mm and CRP ≤ 43.86 D, similar to emmetropes).
Keywords: myopia, classification, emmetropia, axial length of the eye, corneal refractive power, corneal radius
1.Lin LLK, Shih YF, Tsai CB, et al. Epidemiological study of ocular refractions among school–children (aged 6 through 18) in Taiwan. ARVO Abstract. Invest Ophthalmol Vis Sci. 1996;37:S1002.
2.Parssinen O. The increased prevalence of myopia in Finland. Acta Ophthalmol. 2012; 90: 497-502.
3.Parssinen O, Lyyra AL. Myopia and myopic progression among schoolchildren: a three–year follow–up study. Invest Ophthalmol Vis Sci. 1993 Aug;34(9):2794-802.
4.Vitale S, Sperduto RD, Ferris FL 3rd. Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004. Arch Ophthalmol. 2009 Dec;127(12):1632-9.
5.Khoo CY, NG RFS. Methodologies for Interventional Myopia Studies. Ann Acad Med Singap. 2006 Apr;35(4):282-6.
6.Sperduto RD, Seigel D, Roberts J, Rowland M. Prevalence of myopia in the United States. Arch Ophthalmol. 1983 Mar;101(3):405-7.
7.Dobrovolskiĭ VN. [On the question of the causes of myopia]. Iezhenedelnaia klinicheskaia gazeta. 1885;1:13–6. Russian.
8.Strang NC, Winn B, Gilmartin B. Repeatability of post–task regression of accommodation in emmetropia and late–onset myopia. Ophthal Physiol Opt. 1994 Jan;14(1):88-91.
9.Tarutta EP. [Capabilities for preventing progressive and complicated myopia in view of the current knowledge about its pathogenesis]. Proceedings of the 8th Congress of Russian ophthalmologists. Moscow; 2005. p. 712–3. Russian.
10.Zadnik K, Mutti DO, Fusaro RE, Adams AJ. Longitudinal evidence of crystalline lens thinning in children. Invest Ophthalmol Vis Sci. 1995 Jul;36(8):1581-7.
11.Avetisov ES. [Myopia as a manifestation of the body's adaptive response]. In: Proceedings of the 2nd Russian Congress of Ophthalmologists. Moscow; 1968. p.363–73. Russian.
12.Dashevskiĭ AI. [Myopia]. Leningrad: Medgiz; 1962. Russian.
13.Fledelius HC, Goldschmidt E. Oculometry findings in high myopia at adult age: considerations based on oculometric follow-up data over 28 years in a cohort-based Danish high-myopia series. Acta Ophthalmol. 2010 Jun;88(4):472-8.
14.Martin R, Ortiz S, Rio–Cristobal A. White–to–white corneal diameter differences in moderately and highly myopic eyes: partial coherence interferometry versus scanning–slit topography. J Cataract Refract Surg. 2013 Apr;39(4):585–9.
15.Grosvenor T, Goss DA. Role of the cornea in emmetropia and myopia. Optom Vis Sci. Optom Vis Sci. 1998 Feb;75(2):132–45.
16.Schmid K. Myopia Manual. An impartial documentation of all the reasons, therapies and recommendations. Available at: http://www.myopia-manual.de/private/manual-2021-jan.pdf.
17.Ludwig CA, Shields RA, Chen TA, et al. A novel classification of high myopia into anterior and posterior pathologic subtypes. Graefes Arch Clin Exp Ophthalmol. 2018 Oct;256(10):1847-56.
18.Avetisov ES. [Myopia]. Moscow: Meditsina; 1986. Russian.
19.Bushuieva NN. [Modern aspects of etiology, pathogenesis and surgical treatment of progressive myopia]. Oftalmol Zh. 2006;3(1):65–70. Russian.
20.Bystritskiĭ VI. [On the treatment of accommodation spasms and some issues of the pathogenesis of axial progressive myopia]. Ofalmol Zh. 1991;1:28–31. Russian.
21.Thron EZh. [Variability of the components of the optical system of the eye and its clinical importance]. Leningrad: Voienno-meditsinskaia akademiia;1947. Russian.
22.Maliieva OV. [The morphometric indicators of optical environments in patients with myopia, taking into account age and degree of myopia]. Tavricheskii mediko- biologicheskii vestnik. 2012;3(15):85-90.
23.Rykov SA. [The eye as a system. Structure. Function. Relationship]. Kyiv: Medekol;2000. Russian.
24.Zhou XD, Wang FR, Zhou SZ, Shi JS. A computed tomographic study of the relation between ocular axial biometry and refraction. In: Myopia Updates: Proceedings of the 6th international conference on myopia. Editor, Tokoro T. New York, 1998. p.112–5.
25.Park SH, Park KH, Kim JM, Choi CY. Relation between Axial Length and Ocular Parameters. Ophthalmologica. 2010;224(3):188-93.
26.Maliieva OV, Bushuieva NM. Pat. of Ukraine №9,137,183,299. IPC (2014.01): A61F 9/00. [A method for diagnosing myopia progression]. No. u 2014 04603; 06/25/2014. Bul No 12. Ukrainian.
27.Maliieva OV, Bushuyeva NM. Pat. of Ukraine № 83,299 Ukraine. IPC (2013.01): A61F 9/00. [Methods for identifying patients with signs of axial, refractive, mixed or combinatory myopia]. No. u 2013 0837 08/27/2013. Bul No 16. Ukrainian.
28.Fledelius H.C. Is myopia getting more frequent? Across–sectional study of 1416 Danes aged 16 years +. Acta Ophthalmol (Copenh). 1983;61:545–9.
The authors declare no conflict of interest which could influence their opinions on the subject or the materials presented in the manuscript.