Morphometric Characteristics of Axial Length of Eye in Population of the Southern Urals (according to “Ural Very Old Study” and “Ural Eye and Medical Study” Research)

INTRODUCTION: Currently, ametropias are the most important medical and social problem, which occupies one of the leading places in modern ophthalmology. Determination of the length of the anteroposterior eyeball axis (APEA) in myopia ― a type of ametropia directly associated with increase in the axial length of the eyeball ― is an objective method of its diagnosis and identification of progression. Due to the fact that myopia is a multifactorial disease, the study of correlation relationships of the length of the eyeball seems to be extremely relevant.

AIM: To give a statistical assessment of the peculiarities of the axial length of the eyeball in the population of the Southern Urals, depending on age, gender and the respondents' settlement sites, and to determine the correlation relationships of this parameter.

MATERIALS AND METHODS: The analysis was conducted on the base of Ufa Research Institute of Ophthalmology within large clinical and population studies “Ural Eye and Medical Study” (UEMS) and “Ural Very Old Study” (UVOS). Inclusion criteria: signing of voluntary consent to participation in the project, permanent residence in the territory of study; for inclusion in UEMS ― age from 40 to 85 years, in UVOS ― age above 85. UEMS study involved 5899 respondents, UVOS ― 1526. The study protocol suggested evaluation of 683 criteria, 293 of which were answers of respondents to questions of the questionnaire and the results of the general somatic examination, 355 criteria concerned the results of the ophthalmologic examination, 35 ― of laboratory tests. Axial length of the eyeball was measured by the method of ultrasound echo-biometry (A-scanning) (Ultra-compact A/B/P ultrasound system, Quantel Medical, France).

RESULTS: The mean length of the APEA in the UEMS population was 23.31 ± 1.08 mm, in the UVOS population ― 23.11 ± 1.08 mm (p < 0.001). The length of the eyeball axis was 23.31 ± 1.08 mm in the age group 40-84 years and 23.11 ± 1.08 mm in patients in the age category 85 years and older. The multivariate linear regression analysis in UEMS study showed the highest statistically significant association of APEA length with such factors as age (p < 0.001), height (p < 0.001), presence of arterial hypertension (p = 0.02), education level (p < 0.001 ), intraocular pressure (IOP) (p < 0.001), spherical refractive error (p<0.001), depth of anterior chamber (p < 0.001) and angle of anterior chamber (p < 0.001), mosaicism of the eye fundus in the macular region (p < 0.001), presence of myopic maculopathy (p < 0.001), refractive power of the cornea (p < 0.001), corneal volume (p < 0.001), macular pigment density (p < 0.001), thickness of peripapillary layer of nerve fibers (p < 0.001), presence of the epiretinal membrane (p = 0.01). The multivariate linear regression analysis in UVOS study showed statistically significant association of the APEA length with such factors as height (p < 0.001), education level (p = 0.002), corneal refractive power (p < 0.001), spherical refraction error (p < 0.001).

CONCLUSION: In the population of the Southern Urals, statistically significant association of the length of the eyeball axis with such factors as height, education level, refractive power of the cornea and spherical refractive error, was demonstrated. Besides, in the population of UEMC study, there was also noted association with age, the presence of arterial hypertension, intraocular pressure, the depth of the anterior chamber and the angle of the anterior chamber, mosaicism of the eye fundus in the macular region, the presence of myopic maculopathy, corneal volume, density of macular pigment, thickness of the peripapillary layer of nerve fibers, presence of the epiretinal membrane.