Diseases of Lens Yuan He

Cataract Dislocation of lens Classification

Lens thickness→cataractDislocation of lens

Normal lens Structure: oval 、 clear 、 no blood vessels Position: The lens connected with the ciliary body by the suspensory ligament that fixes it behind the iris, in front of the vitreous.

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.

– 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.)

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.

The disorder of the lens commonly if loss of its transparency (cataract ) and abnormality of its position; both can induce severe visual disturbance.

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. Cataracts

Cataracts are a clouding of the lens of the eye. The lens of the eye is a clear oval structure with three layers. The lens works like a camera lens. It focuses light onto the retina in the back of the eye where the image is recorded. The retina is the light sensitive tissue that takes these images and sends signals to the brain. The lens also adjusts the eyes focus, so we can see things clearly both up close and far away.

Pathogeny Age Conformation of the thickness Position of the thickness Cataract Classification

Age-related cataract Congenital cataract Traumatic cataract Diabetic cataract Complicated cataract Drugs and toxicosis cataract Radiative cataract After cataract Pathogeny Cataract Classification (Pathogeny )

According to the age of occurring: – Congenital cataract – Infantile cataract – Juvenile cataract – Adult cataract – Age-related cataract (senile)

Pathologic mechanism It still is not certain what causes these changes in the eye. Research suggests that aging, lifelong exposure to ultraviolet light (usually sunlight), smoking, heredity, eye injuries, high cholesterol and triglycerides, taking cortisone medications for a long time, and diabetes are factors that may increase the risk.

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.

classification According to the site where cataract begins to form: cortical Anterior capsule Posterior capsule subcapsular Age-related cataract nuclear

cortical Posterior subcapsule

Clinical findings: – Bilateral disease – Fixed black spot before the eyes – Visual decrease without pain – Refractive change

cloudy, foggy, or filmy vision not corrected with eyeglasses or contact lenses glare from lamps, sunlight, or snow blurred or double vision decreased night vision light sensitivity dulling of colors frequent eyeglass prescription changes and stronger glasses failing to improve sight

Cortical Cataract 1. 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

2. 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

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)

3. 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.

4. 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

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.

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.

Nuclear cataract It generally begins at the age of 40 It slowly progress Opacity starts at the embryonic or adult nucleus The density of the lens nucleus has been increased, the refractive index obviously strengthens, so myopia often appears.

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.

Subcapsular cataract According to the site where cataract begins to form – Posterior capsular cataract:common – Anterior capsular cataract:rare

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.

Posterior subcapsular cataract

Treatment There isn’t any effective drug to the senile cataract. It is major to operation.

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

Congenital 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.

Pathogeny Heredity ： 1/3 Pregnancy ： Virus infection Medicines, radiation Metabolized diseases

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

1. Anterior polar cataract in the middle of anterior capsular double eyes static not affect the vision too much

2.posterior polar cataract in the middle of posterior capsular double eyes static affect the vision

3.Coronal cataract heredity Double eyes static not affect the vision too much

4.Spots cataract Double eyes static not affect the vision too much

5.Lamellar cataract Usually in children Euchromosome heredity Lamellar opacity around the nuclear “ride” thickness Double eyes and static Affect vision seriously

6.Nuclear cataract Usual Euchromosome heredity Double eyes and static Small pupil: Affect vision seriously big pupil (mydriasis) ： vision increase

7.Total cataract Heredity Euchromosome heredity At birth become total opacity before 1 year of age double eyes Affect vision seriously

8.Film cataract Degeneration of the lens fibres The touch of anterior and posterior capsule, then to be thick and sclerous One or double eyes Affect vision seriously

9.Others Coral cataractSlot cataract

Treatment Whether or not affect with the vision not Observed affect Surgery in time

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.

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

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.

Traumatic Cataract Definition: traumatic cataract is a result of contusion, penetrating, radiation, electric damage to the lens.

Symptoms 1.Contusive cataract “Vossius” ring in the front of the anterior capsule Part or total opacity Capsular membrane break up complications ： dislocation of the lens hemorrhage in the anterior chamber following glaucoma

2.Penetrating cataract Capsular membrane break up Small and light crevasse ： cause part opacity Large and serious crevasse ： cause total opacity lens fibres come out following glaucoma and uveitis

3.Electric cataract The opacity of the anterior capsule and subcapsule Could become total cataract

Treatment Following up ： small and part opacity ， do not affect vision Surgery ： cataract extraction and IOL implantation Treat the complications

Drug-induced and toxic cataracts Definition: Drug-induced and toxic cataract is a result of lens opacity from drugs and toxic materials Glucocorticosteroid cataract chlorpromazine cataract miotic cataract trinitrotoluence （ TNT) cataract

1. Glucocorticosteroid cataract Related with dose and time of the application of drugs Opacity of the posterior capsule→most of the lens fibres Reverse after stopping drugs application in minor population

2. chlorpromazine cataract Dot opacity in the front of the lens Leaves or flower- shape opacity in the middle of the lens

History of drugs and toxic materials application Location and shape of the lens Diagnosis History of drugs and toxic materials application Location and shape of the lens Treatment Drugs application-not abuse Following up Stopping the drugs Surgery

Complicated Cataract Definition: Complicated cataract is a result of lens opacity from uveitis and eye degeneration cause to the metabolization dysfunction of the lens

Clinical finding Primary disease findings ： uveitis, hypermyopia, retinal detachment, glaucoma, tumor, lower IOP, retinitis pigmentosa Usually one eye

Uveitis Glaucoma

Treatment Treat the primary diseases Cataract surgery

Metabolized cataracts Dysfunction of metabolization 1.Diabetic cataract 2.Galactose cataract 3.Tetany cataract

After-cataract Opacity of the posterior capsule after cataract sugeries after the traumatic cataract YAG laser or surgery

Cataract surgeries ICCE (intracapsular cataract extraction ) ECCE (extracapsular cataract extraction ) Phaco (phacoemulsification)

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

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

– 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

IOL implantation

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.

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

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

Ectopia lentis lens’ positional abnormality has two causes: – Rupture of suspensory ligament induced by injury – Congenital aplasia or weakness and laxation of the ligament Subluxation of the lens is often occurs in Marfan’s syndrome patient

Dislocation of lens Ectopia ： at born Dislocation ： after born-----congenital reasons 、 trauma 、 inflammation Total dislocation ： 1. anterior chamber→high IOP 2. vitreous body→uveitis or glaucoma Half dislocation ： part of lens in the pupil area different depth of the anterior chamber iris shaking (iridodonesis) double sight

Marfan’s syndrome

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

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.

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.

Table:criterion of classification of low vision and blindness(WHO,1973)

several major ophthalmopathies causing blindness Cataract: the first cause Keratopathy Glaucoma Trachoma Eye injury and occupation ophthalmopathy Genetic ophthalmopathy Diabetic retinopathy

Conclusion Pathogeny, classification and treatment of the lens diseases Classification, diagnosis and treatment of age related cataract Definition and diagnosis of other kinds of cataracts