The Lens and Vitreous
The lens develops rapidly in the early stages of embryogenesis, during which time it is nourished by the hyaloid vessel. The fully developed lens is avascular; by the second week of life, no remnants of the hyaloid system should remain. The normal lens often exhibits minor imperfections that can be easily detected with magnification in dogs and cats younger than 1 year. These include prominent anterior and posterior Y sutures and minute granules in its nucleus and cortex. A mosaic of brown pigment spots is occasionally seen on the anterior lens capsule near the center of the pupil, representing remnants of embryonic mesoderm. Disease of the vitreous would be expected to influence the lens or retina because of its attachments at the posterior lens surface and the optic disc. Congenital Abnormalities Congenital lens abnormalities include alterations in size or shape. Congenital absence of the lens (aphakia) is uncommon. In microphakia, the margin of the abnormally small lens along with elongated ciliary processes may be observed after pupillary dilation. Microphakia occurs along with other ocular defects in the Saint Bernard and beagle and in cats. Luxation of the microphakic lens may cause glaucoma. Lenticonus is a Read more […]