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Eye Anatomy

nuova anatomia

The following theory, supported by the scientific evidences quoted below, represents an hypothesis able to revalue Dr. Bates’ position who, at the beginning of past century, did not have at disposal the technological means today used in these studies. Please find below a summary of Dr. M. Cigada’s speach during 20th International Congress on Holistic Vision held in Genoa in October 2005.

“We often think that anatomy is an “exhausted” science that, after the pioneers' period of the XV and XVI centuries and the glorious years of the ‘700 and ‘800, nowadays has nothing new to teach us. On the contrary this story tells us there is always something new to learn. In 1995 I.O.V.S. (Investigative Ophthalmology and Visual Science) published a very interesting work by Demer and colleagues on the anatomy of the orbit (1) . Subsequently two new publications (2,3) gave more details on this important part of the visual system. The undersigned has no merit in this discovery and has never taken part to this Group of research. However the organization team of this 20th International Conference has considered such information interesting for the vision educators and asked me to prepare a report of such theory. The most important discovery of such research concerns the form of Tenon’s Capsule, the thin membrane enveloping the eyeball and maintaining it suspended in the middle of the orbital cavity. Based on various histological, anatomic and neuroradiological  observations, Demer and colleagues show that the four Rectus muscles cross Tenon’s capsule in correspondence of the four thickening of such structure; these thickening are inserted directly in the orbital wall and work as pulleys, same as the superior oblique muscle. Obviously this implies important consequences on the biomechanics of eyes movements and consequently on surgery of squint. However the most important point for the consequences that could imply in the visual re-education is that such pulleys are interconnected by a myofascial structure, that is to say by strings of tissue composed by connective, elastin and muscular smooth fibre. In other words, approx in correspondence of the equator line there are some anatomic structures with contractile properties surrounding the eye-ball like a ring; these structures show an abundant autonomic innervation (2) and  consequently we can suppose that, when contracted simultaneously, they are able to deform the eye ball making it longer, thus making it myopic.  At present stage of knowledge there is no certainty that this becomes true in reality, but it any case the interesting discovery is that of an anatomic structure that might cause a functional myopia, likewise affirmed by Bates. Bates did not know these details about the anatomy of Tenon’s capsule and had consequently made the hypothesis that an excessive contraction of extra-ocular muscles (rectus and obliquus) could deform the bulb making it myopic. It is known that this theory has been heavily criticized by the official ophthalmology also because in this process striated voluntary muscles would be involved.  On the contrary the structures illustrated by Demer is composed by smooth muscular fibres, involuntary and under the control of the autonomous nervous system, thus of the emotions.

Fig. 1 shows the anatomy of muscles and peribulbar fascia according to this new theory. In the subsequent years other details have come out, as shown in fig. 2. Each rectus muscle could actually be formed by two strata: an orbital one, closer to the orbit wall, and one more inside the bulb. While the bulbar stratum crosses Tenon’s capsule in order to connect itself to the eye ball, the orbital stratum of each rectus muscle would insert itself on the edge of the “pulley” modifying its position during eye movements. Even though this last observation does not seem directly involved in the activity of the vision educators, it’s interesting to notice how in all these years strabismus surgery could be carried out even though it was based on wrong theoretic principles”.

1] J.L.Demer, J.M.Miller, V.Poukens, H.V.Vinters, B.J.Glasgow
Evidence for fibromuscular pulleys of the recti extraocular muscels
Invest. Ophthalmol. Vis. Sci. 1995 ;36: 1125-1136 Bibliography

2] J.L.Demer, V.Poukens, J.M.Miller, P.Micevych
Innervation of extraocular pulley smooth muscle in monkeys and humans
Invest. Ophthalmol. Vis. Sci. 1997; 38: 1774- 1785

[3] R.A.Clark, J.M.Miller, J.L.Demer
Three-dimensional location of human rectus pulleys by path inflections in secondary gaze position
Invest. Ophthalmol. Vis. Sci. 2000; 41: 3787- 3797

(*) Dr. Mario Cigada (Italy) – Degree in Ophthalmology in 1987, Degree in Psychotherapeutics in 1992. Since 1992 teacher at the Scuola Europea di Psicoterapia Ipnotica of AMISI. He conducted seminars in “Orthoptists  - Assistant in Ophthalmology” at the University of Milan and he is teacher  at the Specialization School in clinical Neuro-psychology of the Faculty of Psychology in Turin. Presently he is Professor in the Degree course  of “Orthoptics - Assistant in Ophthalmology” for the academic years and for the course of Visual handicap re-education. He is teacher at the School for Vision educators of AIEV.