Monocular Depth Estimation (Literature Review)

Background. The physiological basis of spatial perception is traditionally attributed to the binocular system, which integrates the signals coming to the brain from each eye into a single image of the three-dimensional outside world. The perception of three-dimensionality, however, is also possible due to the evolutionarily older monocular system of spatial perception. Normally, the binocular mechanism plays the leading role in depth perception, and its violations lead to a shift towards the monocular. In this regard, one of the relevant areas of ophthalmology and neurophysiology is the study of the features of monocular depth estimation in normal conditions and cases of ophthalmic pathology.Purpose: to study the literature data on the monocular depth estimation mechanism, methods of its assessment, as well as the peculiarities of its manifestations in normal conditions and cases of ophthalmic pathology.Materials and methods. The literature analysis of publications on PubMed, eLibrary, Cyberleninka and crossref metadata search was carried out.Results. The review considers modern ideas regarding monocular depth cues that can ensure the effective operation of the monocular mechanism of spatial vision. The stereokinetic effect (SE) is considered in detail. The possibilities of using SE assessment methods to evaluate the state of spatial vision mechanisms in cases of ophthalmic and neurological pathology have been studied.Conclusion. There are a number of monocular depth cues that can ensure the effective operation of the monocular mechanism of spatial vision, such as: perspective, light and color effects, accommodation and knowledge of the true sizes of the objects acquired with experience. Stereokinetic effect caused by the successive displacement of projections of circular eccentric images on the retina, which allows to evaluate relationship of monocular and binocular mechanisms of spatial perception, has a particular importance for ophthalmology practice. In patients with binocular vision disorders (amblyopia and strabismus), a decrease in monocular and an increase in binocular SE indicators were observed, whereas only a decrease in monocular indicators is more typical for organic ocular fundus pathology. At the same time, changes in SE indicators can serve as additional criteria for evaluating the efficacy of functional treatment of binocular disorders.