Abstract
Background The development of visual functions takes place in the first months of postnatal life and is completed around the one year of age. In this period, the maturation of the retina and the visual pathways occur, and binocular bonds are established at the level of the visual cortex. During this phase and then for a few years, a certain plasticity of the visual functions remains, which seem therefore susceptible to change both in a pejorative sense (by pathogens) and in an improving sense (for example, by therapeutic measures). This plasticity involves also the oculomotor system. Due to this plasticity, many researchers believe that there are some functional correlations between the visual and the stomatognathic apparatus. But the scientific evidence of this statement has not been clarified yet. Aim The purpose of this review is therefore to analyze the clinical data in this field and finally to establish their level of evidence. Studies have been collected from the main databases, based on keywords. Results The results showed a middle level of evidence since most of the data derive from case-control studies and cross-sectional studies. Conclusions The level of evidence allows establishing that there is a correlation between ocular disorders (myopia, hyperopia, astigmatism, exophoria, and an unphysiological gait due to ocular convergence defects) and dental occlusion, but it is not possible to establish the cause-effect relationship. Future studies should be aimed at establishing higher levels of evidence (prospective, controlled, and randomized studies).
Highlights
The level of quality is mainly affected by the lack, in literature, of an adequate number of prospective longitudinal reports that could really clarify the relationship between the visual system and the stomatognathic apparatus
A part of the studies pointed on the anatomical contiguity between the stomatognathic and visual apparatus, and other studies focus on neurological connections
A considerably higher prevalence of ocular convergence defects was assessed in adults affected by Temporomandibular disorders (TMD) presenting limited maximal opening, myofascial pain, and pain in the neck shoulder area, with respect to healthy individuals [9]
Summary
The visual apparatus consists of equal and symmetrical organs located, for the great part in the anterior region of the head, below the forehead, and at the sides of the nose root [1].Among these organs, the main one is the eye; the others, called accessory organs of the eye, can be grouped into the oculomotor system, and a protective structure.The oculomotor system allows moving the eye towards certain sectors of the environment; its particular organization and its connections with the brain make it suitable to transmit to the analytical neurological centres a complex of signals that faithfully repeat the images of the external world [1].The eyeball, together with the oculomotor system and the protective apparatus, is located in the orbital cavity that is a deep, bone cavity, formed by the convergence of the processes of the maxillary, the zygomatic, and the palatine bones, in the lower part; by the convergence of the frontal and the sphenoid bones superiorly; from the lacrimal ethmoid and, minimally, maxillary, and sphenoid bones, medially; and from the zygomatic and the sphenoid bones, laterally [1].The eyeball is contained in a connective structure calledTenon's capsule, which separates it from the orbital fat. The visual apparatus consists of equal and symmetrical organs located, for the great part in the anterior region of the head, below the forehead, and at the sides of the nose root [1] Among these organs, the main one is the eye; the others, called accessory organs of the eye, can be grouped into the oculomotor system, and a protective structure. The development of visual functions takes place in the first months of postnatal life and is completed around the one year of age In this period, the maturation of the retina and the visual pathways occur, and binocular bonds are established at the level of the visual cortex. Future studies should be aimed at establishing higher levels of evidence (prospective, controlled, and randomized studies)
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