Investigation of Normal and Myopic Eyes by Computer Tomography
A topometric oculoorbital study on eight myopic (6.0, 7.5, 8.0, 10.0, 12.0, 20.0, 24.0, and 28.0 D) and five normal persons by X-ray computed tomography (CT) was undertaken. To 5-7 D at maximal convergence the optical nerve is easily located. The vitreous body has uniform radiographic density [ 10*#x2013;15 Hounsfield units (HU) ], but at 6–7 D in horizontal scans -2 to +23 HU density zones stretch from the nasofrontal to the temporoposterior part of the orbit. The zones’ density increases with the increase in myopia. At 10.0 D the gap between the eye and orbit is so narrow that at maximal convergence the optical nerve is squeezed between the eye and the orbital wall, and the exterior oculomotor muscle is pressed against the wall. At myopia of 20–28 D at maximal convergence, the eye globe is squeezed because the nasolanterior and temporoposterior parts of the eye are pressed by the orbit. The normal eye’s geometrical center at convergence does not change position, but with myopia the center is moving; with high myopia the eye and optical nerve are under the influence of dynamic loading. The formation of the various radiographic density zones in the vitreous are caused by the above-mentioned mechanical factors.