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1、1,Disease of the lens,EYE No.1,2,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.,EYE No.2,3,Anatomy: The lens is composed of lens capsule and lens fiber. The lens capsule is a la
2、yer of elastic homogeneous membrane. The lens fibers are the extension and elongation forwards and backwards of the epithelial cells at the equator.,4,It is approximately 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 o
3、nly can views the center portion through the pupil.),5,Physiology of the lens The lens is s kind of transparent and non-blood vessel tissue. It is an important part of refractive media of the globe. The lens nourishment are offered by aqueous humor.,6,The disorder of the lens commonly if loss of its
4、 transparency (cataract ) and abnormality of its position; both can induce severe visual disturbance.,7,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.,EYE
5、No.4,8,Classification,According to the age of occurring: Congenital cataract Infantile cataract Juvenile cataract Adult cataract Age-related cataract (senile),EYE No.5,9,According to etiology: Traumatic cataract : blunt or penetrating injury Complicated cataract: uveitis Metabolic cataract: diabetes
6、 Drug-induced or toxic cataract Developing cataract After-cataract,10,age-related cataract,It is the most common cataract, often seen in the olds with age more than 50 years old. The incidence of the disease is 100% when the patient exceed 80 years old.,EYE No.6,11,Pathologic mechanism,The disease i
7、s related with several factor: Ultraviolet ray Genetic factor Systemic disease such as diabetes, hypertension. Lens nourishment and metabolic condition,12,Clinical findings: Bilateral disease Fixed black spot before the eyes Visual decrease without pain Refractive change,EYE No.7,13,classification A
8、ccording to the site where cataract begins to form:,cortical,Anterior capsule,Posterior capsule,subcapsular,Age-related cataract,EYE No.8,nuclear,14,cortical cataract It is divided into 4 stages:,Incipient stage: To begin opacity appears at the periphery of anterior and posterior cortex The center l
9、ens is almost clear, the pupillary area isnt affected, commonly without influencing vision. To be diagnose after mydriasis under slit-lamp examination. To develop slowly,EYE No.9,15,EYE No.10,Immature stage(intumescent stage) The opacity gradually becomes obvious The cortex absorbs water to become s
10、wollen Iris projection: the characteristic of this stage Vision has obviously decreased The fundus cant be observed in Some patient may induce acute attack of glaucoma due to shallow anterior chamber,16,Iris projection: To examine with oblique illumination, the iris shadow on projected side falls on
11、 opaque cortex in deep layer, a crescent projection appears at the pupil of the side.( because there is transparent cortex between iris pupillary margin and lens cortex),17,Mature stage The lens has become opaque at all in cream white color The iris projection disappeared The fundus cant be looked i
12、n Vision decreases to light perception or hand movement But the light seeking and color sensation are in normal.,18,Hypermature stage When the mature stage continues for over long time,the water in the lens has been lost continuously, the volume of the lens diminishes, the capsule shrinks,the anteri
13、or chamber deepens with iridodonesis. Vision may increase suddenly,19,Morgagnian cataract: the lens fibers are decomposed and dissolved in cream-white liquefaction, brown-yellow hard nucleus sinks down, the anterior chamber in upper part become deep.,20,When the lens capsule ruptured Phaco-anaphylac
14、tic uveitis Phacolytic glaucoma:the lens cortex blocked the anterior chamber angle, or the lens nucleus dislocates into the anterior chamber or into vitreous body.,21,nuclear cataract,It generally begins at the age of 40 It slowly progress Opacity starts at the embryonic or adult nucleus,EYE No.13,T
15、he density of the lens nucleus has been increased, the refractive index obviously strengthens, so myopia often appears.,22,Nuclear opacity is grayish-yellow at first, then gradually becomes thick in yellowish-gray brown or brownish-black. In that time, the fundus cant be seen. The nuclear changes of
16、ten continue unchanged for a long period(2030 years), uneasy to be matured.,23,Subcapsular cataract,According to the site where cataract begins to form Posterior capsular cataract:common Anterior capsular cataract:rare,24,The opacity often occur to the posterior capsular center, so vision decreases in early stage. The cataract may develop to become cortical opaque then total cataract.,25,Treatment,There isnt any effective drug to the senile cataract. It is major to operation.,
