Disease of te lens分析课件.pptVIP

Disease of the lens Anatomy and Physiology of the lens Position: The lens connected with the ciliary body by the suspensory ligament that fixes it behind the iris, in front of the vitreous body. Anatomy : The lens capsule is a layer of elastic homogeneous membrane. The lens fibers are the extension and elongation forwards and backwards of the epithelial cells at the equator. It is about 9mm in diameter and 4-5mm in the thickness. But we only use 2.5-4mm in the center (because the iris keeps out the rest lens and only can views the center portion through the pupil.) The lens is kind of transparent and non-blood vascular tissue. It is an important part of refractive media of the globe. The lens’ nourishment are offered by aqueous humor. what is a cataract? The disorder of the lens commonly if loss of its transparency can induce severe visual disturbance. (cataract ) . Cataract is the first cause of blindness in China and other many developing country. There are one million of cataract sufferer who are in need of operation to restore their visions. Classification Congenital cataract Age-related cataract Traumatic cataract : blunt or penetrating injury Complicated cataract: uveitis Metabolic cataract : diabetes Drug-induced or toxic cataract Developing cataract After-cataract Symptoms Blurring or dimness of vision colors appear faded Sensitivity to light and glare Double or multiple vision Change in refraction Treatment There isnt any effective drug to the cataract. Surgery is the only way to remove the cataract. Operating method Intracapsular cataract extraction (ICCE) Extracapsular cataract extraction (ECCE) Phacoemulsification Visual correction afater cataract operation By intraocular lens: it is the most effective method for correction of aphakia By contact lens: the method is less used because of more complications and using process more trouble By glasses: binocular aphakia patient Intraocular Lens An IOL is a tiny,transparent,co