Patterns of Eye Structural and Functional Changes in Presbyopia

Aim. To identify patterns of structural and functional interrelationship in the eye in presbyopia formation. Methods. 60 patients with emmetropia without eye diseases in two age groups: from 18 to 30 years old and from 45 to 60 years old were examined. In addition to the standard ophthalmic examinations the following methods were used: assessment the pupil size in different lighting conditions, examination of the anterior and middle segment of the eye by means of ultrasound biomicroscopy and using a rotating Scheimpflug camera («Pentacam»). Results. Patients with presbyopia showed lens enlargement with simultaneous shortening of anterior portion of Zinn ligament, reduction of anterior chamber depth and volume, decrease of an adjunction angle between the iris and the cornea, ciliary body thickness reduction, and the increased distance between trabeculae and the crown of the ciliary body. The most pronounced decrease of the thickness of the ciliary body, length of the Zinn ligament and the increase of distance between trabeculae and ciliary processes were noted in the horizontal plane with a maximum change in the internal segment. The spatial deformation of the posterior chamber and changes of the anterior chamber angle were more pronounced in the lower and outer quadrants. Pearson’s correlation analysis revealed the vanishing of a significant number of correlations, characteristic for the physiologically properly formed eye with a proportionate refraction and the appearance of new relationships, directed to preserve the normal physiology of intraocular fluid, and stability of visual image receiving. Conclusion. Presbyopia development is characterized by a set of structural and functional changes, the spatial transformation of the eyeball that must be considered when performing surgical interventions in patients with presbyopia.