Induced deformations, similar to the posterior pole deformations due to advanced myopia, were studied in a series of 30 rabbits. The induced deformations were produced by means of a specially designed cup. An analysis of the applicability of the shell theory is made, and it is concluded that the thin shell theory is applicable to the mechanical study of the eyes. The basic experiment consisted of introducing a controlled deformation at different pressure levels; a wide range of types of increments and times of substained deformations were studied. It is concluded that the scleral tissue is an elastic material and has a fairly high ‘Creep’ rate. The material properties indicate that the eye can reaccommodate induced pressure, and thus glaucoma and myopia could be present without external indications of ‘high pressure’ in the eye.
As part of a bio-engineering approach to study myopia, a structural model of the eye is proposed. The model is based on structural laws as employed by civil engineers, and on mechanical properties of the sclera and vitreous previously analyzed by the authors. The described structural behavior relates many loose clinical observations and indicates that progressive myopia should be considered a mechanical problem due to an abnormal vitreous pressure rather than an optics problem. From this bio-engineering approach, vitrectomy is suggested as the appropriate solution.
As part of the search for a bioengineering model of the eye, the interaction between instantaneous changes of pressure in the anterior and vitreous chambers are studied. A description of the experiments as well as data evaluation is given. The results indicate a linear relationship between the chambers and a diaphragm effect of the system lens-iris-zonula-ciliar body.
The mechanical behavior of the iris-lens-zonule-ciliary body (ILZC) system under intraocular pressure variations, measured with Scan A, is studied on a series of 20 rabbit eyes. The experiments indicate that the ILZC system behaves like a partition between the anterior and vitreous chambers and not like a supporting structural member. The observed behavior is related to previous clinical observations and to the biostructural model of the eye described in a previous paper by the authors.
As part of the bio-engineering approach to study myopia and also as a complement to the bio-structural model of the eye presented by the authors, an analog for the study of internal forces is analyzed. The behavior of the model indicates not only that the forces involved in the development of progressive myopia, but those of pre- and post-trabecular glaucomas could be studied and related with such an analog model, supporting the author’s feelings that many medical problems could be successfully explained by engineering methods and techniques.
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