Vertebrate Visual Optics --Ontogeny Phylogeny and Function of the Lens

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The vertebrate eye consists of two refractive components, the crystalline lens and the cornea.The lens is a cellular structure that continues to develop through life. Lens optical (focussing) function is governed by its shape and its refractive index distribution. It is also affected by whether accommodation (the ability to adjust the focussing power) is brought about by changes in lens (and sometimes corneal) shape or through lens movement. The cornea is essentially not refractive when the eye is in water. In addition, the optical development of the eye can be altered experimentally by depriving the eye of clear vision, especially during eye growth.******Projects will explore: 1)Pre-teleost vs. teleost lensoptical function While the typical (teleost) fish lens has received some experimental attention, that of species representing earlier evolutionary development have not. A laser scanning apparatus developed by the applicant will be used to study lens optical function in a variety of modern and representative primitive fish. 2) Optical Development of the Snake Eye The spectacle is a transparent scale that covers the front of the eye and is found in all snakes. When the skin is shed, the spectacle becomes cloudy. Thus, the snake eye is periodically (1 to 4 times per year) subject to blurred vision. The effect of this natural deprivation of clear vision on ocular refractive development will be investigated to see if refractive development is periodically shiifted in the myopic direction. 3)Chromatic Aberration of the Lens In Vitro While the longitudinal chromatic aberration (effect of wavelength on focal length) of the eye and lens is substantial, the influence of age is not clear. A new scanning laser system, using both a short wavelength diode laser (420nm) as well as a red (630nm) laser, has been developed and will be used to examine this issue using animal lenses. 4)In Vitro lens Development. Lentoids are transparent three-dimensional multicellular structures that form from primary lens epithelial cell cultures. The roles of various growth factors in inducing lentoid formation will be explored using a variety of lens cell cultures. The goal of this research is to enhance lens epithelial cell differentiation in order to produce lentoids with lens-like optical properties approaching that of the natural lens.  5) Use of cultured eyetissue as in vitro ocular toxicology assays. A variety of lens and corneal cell cultures will be used to develop a battery of assays that can be used in eye toxicology in order to minimize the use of live animals in testing to evaluate the risk of using new eye-related products.*****