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 layer 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 only 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 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 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 –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 is 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 According 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 lens is almost clear, the pupillary area isn’t 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 swollen –Iris projection: the characteristic of this stage –Vision has obviously decreased –The fundus can’t 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 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 can’t be looked in –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 anterior 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-anaphylactic 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 The 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 can’t be seen. The nuclear changes often continue unchanged for a long period(20~30 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 isn’t any effective drug to the senile cataract. It is major to operation.

26 Operative time At the immature or mature stage The vision is lower than 0.3 to influence with patient’s work and life

27 Preoperative examination Systemic Ocular part: –Exam visual acuity –Slit-lamp microscope –Corneal curvature –A/B ultrasonic exam

28 Operating method Phacoemulsification extraction of cataract –Characteristic: transparent corneal incision(3.2mm) To crush the hard lens nucleus to be chyloid with ultraemulsifier and extracted To implant the foldable intraocular lens in the lens capsular bag

29 –strongpoint: Self-healing wound The corneal astigmatism after operation is fine Visual restoration is soon –Shortcoming: The apparatus is expensive Some descendible disease can’t choice this method Too hard lens nucleus may not adopt this method

30 Extracapsular cataract extraction and posterior chamber intraocular lens implantation –The corneoscleral tunnel incision(6mm) –dispense with suture –The lens is hard(unfoldable) –The patient can get good vision soon after operation –The corneal astigmatism after operation is less.

31 Intracapsular cataract extraction –The incision is bigger than ECCE, so the corneal astigmatism is high. –The complications are more than that of ECCE

32 Visual correction fater cataract operation After cataract surgery, the aphakia is in a state of high hyperopia (+10~ +12 diopters) –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

33 congnital cataract Definition: congenital cataract is a result of lens growing and developing disturbance in the process of fetal development. Causes: –Endogenous:chromosome with heredity. –Exogenous:by mother’s or fetal systemic disorder. EYE No.26

34 Clinical findings It commonly is bilateral, static. A few develop continuously after birth. It may be classified according to the site and the shape of lens opacity. –Anterior polar cataract –Posterior cataract –Perinuclear cataract –Nuclear cataract –Total cataract, and so on

35 treatment Whether or not affect with the vision not Observed affect Surgery in time EYE No.31

36 Opportunity of operation: the earlier the operation is done, the greater the chance to get good vision becomes. –The surgery may be done some weeks after birth. –It should be done generally in baby with age of 3~6 months. –But the IOL implantation must do after 3 years old. EYE No.32

37 Treatment purpose: –Reserve vision –Prevent amblyopia –Promote development of fusion function Surgery method –Extracapsular cataract extraction –Cataract suction –IOL implantation after the suction’s patient is 3 years old

38 The correction: –By glasses:suitable to binocular aphakia with elder age. It is simple and convenient, easy to adjust and replace. –By contact lens ： suitable monocular aphakia in children. But it is troublesome to take off, and so on. –By IOL:After 3 years,the patient can do the implantation to obtain better vision. –Amblyopia should be treated actively and timely.

39 Traumatic cataract EYE No.33 Drug-induced cataract Toxic cataract

40 Ectopia lentis lens’ positional abnormality has two causes: –Rupture of suspensory ligament induced by injury –Congenital aplasia or weakness and laxation of the ligament

41 Subluxation of the lens is often occurs in Marfan’s syndrome patient

42 Treatment The lens is extracted when the vision is affected or the complications occurred.

43 Prevention and treatment of blindness Blindness also indicates that both eyes lose the ability to distinguish surroundings,the patient isn’t able to be competent at some occupations, even to take care of himself. EYE No.43

44 Blindness: the best corrected visual acuity of better eye is lower than 0.05,or the visual field is less than 10 degrees while the best corrected vision of better eye is more than The low vision:the best corrected vision of better eye is more than 0.05, but lower than 0.3.

45 Table:criterion of classification of low vision and blindness(WHO,1973) EYE No.44

46 several major ophthalmopathies causing blindness Cataract: the first cause Keratopathy Glaucoma Trachoma Eye injury and occupation ophthalmopathy Genetic ophthalmopathy Diabetic retinopathy EYE No.45