Diseases of Lens

Yuan He

Cataract

Dislocation of lens

Classification

Lens thickness→cataract Dislocation of lens

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

PathogenyAgeConformation of the thicknessPosition of the thickness

Cataract Classification

Age-related cataract Congenital cataract Traumatic cataract Diabetic cataract Complicated cataract Drugs and toxicosis cataract Radiative cataract After cataract

Cataract Classification(PathogenyPathogeny)

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

Pathologic mechanismPathologic 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 CataractAge-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.

classificationclassificationAccording to the site where cataract According to the site where cataract

begins to form:begins to form:

cortical

Anterior capsule

Posterior capsule

subcapsular

Age-related cataract

nuclear

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 lensesglare from lamps, sunlight, or snowblurred or double visiondecreased night visionlight sensitivitydulling of colorsfrequent eyeglass prescription changes andstronger glasses failing to improve sight

Cortical CataractCortical 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 cataractNuclear 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 cataractSubcapsular cataractAccording 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 Posterior subcapsular cataractcataract

TreatmentTreatment

There isn’t any effective drug to the senile

cataract.

It is major to operation.

Operative timeOperative time

At the immature or mature stageThe vision is lower than 0.3 to influence

with patient’s work and life

Congenital CataractCongenital 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.

PathogenyPathogeny

Heredity： 1/3Pregnancy： Virus infection

Medicines, radiation

Metabolized diseases

Clinical findingsClinical 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

2.2.posterior polar posterior polar cataractcataract

• in the middle of posterior capsular

double eyes staticaffect the vision

3.3.Coronal cataractCoronal cataract

• heredity

• Double eyesstatic not affect the

vision too much

4.4.Spots cataractSpots cataract

• Double eyesstatic not affect the

vision too much

5.5.Lamellar cataractLamellar cataract

Usually in children Euchromosome

heredity Lamellar opacity

around the nuclear “ride” thickness

• Double eyes and static

Affect vision seriously

6.6.Nuclear cataractNuclear cataract

Usual Euchromosome

heredity

• Double eyes and static

Small pupil: Affect vision seriously

big pupil (mydriasis) ：vision increase

7.7.Total cataractTotal cataract

Heredity

Euchromosome heredity At birth

become total opacity before 1 year of age

double eyes Affect vision seriously

8.8.Film cataractFilm 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

9.9.OthersOthers

Coral cataract Slot cataract

Treatment 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 CataractTraumatic Cataract

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

SymptomsSymptoms

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

2.2.Penetrating Penetrating cataractcataract

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

3.3.Electric cataractElectric cataract

The opacity of the anterior capsule and subcapsule

Could become total cataract

Treatment Treatment

Following up ： small and part opacity ， do not affect vision

Surgery ： cataract extraction and IOL implantation

Treat the complications

Drug-induced and toxic cataractsDrug-induced and toxic cataracts

Definition: Drug-induced and toxic cataract is a result of lens opacity from drugs and toxic materials

Glucocorticosteroid cataractchlorpromazine cataractmiotic cataracttrinitrotoluence （ TNT) cataract

1. 1. Glucocorticosteroid Glucocorticosteroid cataractcataract

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. 2. chlorpromazine chlorpromazine cataractcataract

Dot opacity in the front of the lens

Leaves or flower-shape opacity in the middle of the lens

Diagnosis

History of drugs and toxic materials applicationHistory of drugs and toxic materials application Location and shape of the lensLocation and shape of the lens

Treatment Drugs application-not abuse

Following upStopping the drugs

Surgery

Complicated CataractComplicated Cataract

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

Clinical findingClinical finding

Primary disease findings ： uveitis, hypermyopia, retinal detachment, glaucoma, tumor, lower IOP, retinitis pigmentosa

Usually one eye

Uveitis Uveitis Glaucoma

Treatment Treatment

Treat the primary diseasesCataract surgery

Metabolized cataractsMetabolized cataracts

Dysfunction of metabolization

1.1.Diabetic cataractDiabetic cataract2.2.Galactose cataractGalactose cataract3.3.Tetany cataractTetany cataract

After-cataractAfter-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 examinationPreoperative examinationSystemicOcular part:

– Exam visual acuity– Slit-lamp microscope– Corneal curvature – A/B ultrasonic exam

Operating methodOperating 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 implantationIOL 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 Visual correction fater cataract operationoperation

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 lentisEctopia lentislens’ positional abnormality has two

causes:– Rupture of suspensory ligament

induced by injury – Congenital aplasia or weakness and

laxation of the ligamentSubluxation of the lens is often occurs in

Marfan’s syndrome patient

Dislocation of lensDislocation of lensEctopia ： at bornDislocation ： after born-----congenital

reasons 、 trauma 、 inflammationTotal 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 syndromeMarfan’s syndrome

Marfan’s syndromeMarfan’s syndrome

TreatmentTreatment

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

Prevention and treatment of Prevention and treatment of blindnessblindness

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 0.05.

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 Table:criterion of classification of low vision and low vision and

blindness(WHO,1973)blindness(WHO,1973)Best corrected vision

Best vision lower than

Lowest vision equal to or lower

1 0.3 0.1 Low vision 2 0.1 0.05(FC/3m)

3 0.05 0.02(FC/1m) 4 0.02 Light perception

Blindness

5 No light perception

several major ophthalmopathies several major ophthalmopathies causing blindnesscausing blindness

Cataract: the first cause Keratopathy Glaucoma Trachoma Eye injury and occupation ophthalmopathy Genetic ophthalmopathy Diabetic retinopathy

ConclusionConclusion

Pathogeny, classification and treatment of the lens diseases

Classification, diagnosis and treatment of age related cataract

Definition and diagnosis of other kinds of cataracts