diseases of lens yuan he. cataract dislocation of lens classification
TRANSCRIPT
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