![]() The two classification methods complement each other in dogs, it is possible to encounter any of the possible glaucoma combinations: primary open angle, primary narrow angle, primary closed angle, secondary open angle and secondary closed angle glaucoma. In some breeds, examination of the angle will help determine whether the eye is at risk for developing primary glaucoma. Moreover, in patients presenting with unilateral primary glaucoma, the contralateral eye is highly likely to develop the disease (on average within 8 months). On the other hand, dogs with primary glaucoma will require lifelong treatment. More important, if unilateral glaucoma is deemed secondary, it means the contralateral eye is not necessarily at risk. It is possible that secondary glaucoma may be cured if the primary ocular disease is treated successfully (e.g. These classifications are not mere semantics rather, they have significant clinical implications. The angle may be open (in which case the obstruction is further downstream), narrow or closed. Alternatively, glaucoma can be classified according to the state of the drainage angle.lens luxation, uveitis) decreases outflow. Based on the cause, it can be classified as primary, where outflow problems are linked to genetic abnormalities in the drainage pathway, or secondary, where another ocular disease (e.g.Glaucoma may be classified in one of two ways: The importance of this route varies among species, accounting for 15% of the total drainage in dogs and 33% in horses, but only 3% in humans. The drainage continues through the uveal and corneoscleral meshworks, eventually exiting the eye into the systemic venous circulation.Īqueous humor may also exit the eye through an unconventional path, in which it diffuses through the iris and ciliary body (or through the vitreous) into the suprachoroidal space from there, the fluid drains into the venous circulation. After circulating in the anterior chamber and supplying the metabolic requirements of the lens and cornea, this fluid exits the eye through the iridocorneal angle (between the cornea and iris), which is spanned by pectinate ligaments. Production and drainage of aqueous humorĪqueous humor is transparent fluid produced in the ciliary processes, from where it flows into the posterior chamber and through the pupil into the anterior chamber. In clinical practice, glaucoma is caused by drainage disturbances, while cases of increased production are not recognized. IOP is the result of a balance between production and drainage of aqueous humor. However, the disease can still be described generally as an elevation in intraocular pressure (IOP) that is incompatible with normal ocular function. The definition of glaucoma is changing rapidly as our understanding of the pathogenesis of damage to the retina and optic nerve improves.
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