Офтальмохирургия (Jan 2016)
Biomechanical properties of the sclera in patients with different types of refraction
Abstract
Purpose. To determine biomechanical age-specific features of the scleral tissue and the axial length of the eye.Material and methods. The study investigated 144 isolate d fragments of the sclera of 38 cadaver human eyes at the age from 40 to 75 years. [The average value of the axial length of eyes: 23.56±3.06mm (20.05-26.62).] Samples of sclera with a standard 5mm width were cut out with microsurgical blade from the anterior, equatorial and posterior areas of the eye. Biomechanical test of scleral samples was carried out using the universal testing Instron-3322 machine.Results. The highest indices of scleral strength and Jung’s Modulus (JM) were obtained at the age of over 60 years. A strength increase of the sclera was noted in all segments of the eyeball, amounting to 15.6±0.4MPa in the anterior segment in case of hyperopia; 12.3±0.5MPa in myopia; in norm: 15.2±0.8MPa; in the posterior pole of the eye these indices also increased and were 13.1±0.5MPa in hyperopia, 10.2±0.7MPa for myopia, in norm: 12.8±0.7МPа. The JM has significantly (p <0.05) the highest value in the anterior segment 49.21±4.1МPа in hyperopia, 37.05±5.5МPа for myopia, in norm: 48.29±5.3МPа; the lowest values were determined in the posterior pole of the eye amounting 37.25±2.2МPа in hyperopia, 24.07±7.1МPа for myopia, in norm: 36.78±1.5МPа.Conclusions. Biomechanical characteristics of scleral tissue fragments show that the strength and resilience of the scleral tissue increases with age, however, the heterogeneity of these indices remains by segments, that leads to a variability in its biomechanical status.
