Download 晶状体病

EYE No.1
Disease of the lens
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EYE No.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.
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• 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.
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– 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.)
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• 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.
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• The disorder of the lens
commonly if loss of its
transparency (cataract ) and
abnormality of its position; both
can induce severe visual
disturbance.
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EYE No.4
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.
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EYE No.5
Classification
• According to the age of occurring:
– Congenital cataract
– Infantile cataract
– Juvenile cataract
– Adult cataract
– Age-related cataract (senile)
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• According to etiology:
– Traumatic cataract : blunt or
penetrating injury
– Complicated cataract: uveitis
– Metabolic cataract: diabetes
– Drug-induced or toxic cataract
– Developing cataract
– After-cataract
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EYE No.6
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.
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Pathologic mechanism
• The disease is related with several
factor:
– Ultraviolet ray
– Genetic factor
– Systemic disease such as diabetes,
hypertension.
– Lens nourishment and metabolic
condition
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EYE No.7
• Clinical findings:
– Bilateral disease
– Fixed black spot before the eyes
– Visual decrease without pain
– Refractive change
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EYE No.8
classification
According to the site where cataract begins
to form:
Age-related cataract
cortical
nuclear
subcapsular
Anterior
capsule
Posterior
capsule
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EYE No.9
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 slitlamp examination.
– To develop slowly
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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
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• 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)
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• 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.
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• 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
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• Morgagnian cataract: the lens fibers are
decomposed and dissolved in creamwhite liquefaction, brown-yellow hard
nucleus sinks down, the anterior chamber
in upper part become deep.
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• 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.
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EYE No.13
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.
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• 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.
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Subcapsular cataract
• According to the site where
cataract begins to form
– Posterior capsular cataract:common
– Anterior capsular cataract:rare
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• 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.
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Treatment
• There isn’t any effective drug to
the senile cataract.
• It is major to operation.
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Operative time
• At the immature or mature stage
• The vision is lower than 0.3 to
influence with patient’s work and
life
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Preoperative examination
• Systemic
• Ocular part:
– Exam visual acuity
– Slit-lamp microscope
– Corneal curvature
– A/B ultrasonic exam
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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
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– 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
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• 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.
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• Intracapsular cataract extraction
– The incision is bigger than ECCE, so
the corneal astigmatism is high.
– The complications are more than that
of ECCE
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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
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EYE No.26
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.
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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
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EYE No.31
treatment
Whether or not affect with the vision
not
Observed
affect
Surgery in time
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EYE No.32
• 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.
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• 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
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• 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.
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EYE No.33
Traumatic cataract
Drug-induced cataract
Toxic cataract
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Ectopia lentis
• lens’ positional abnormality has two
causes:
– Rupture of suspensory ligament induced
by injury
– Congenital aplasia or weakness and
laxation of the ligament
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• Subluxation of the lens is often
occurs in Marfan’s syndrome
patient
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Treatment
• The lens is extracted when the
vision is affected or the
complications occurred.
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EYE No.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.
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• 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.
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EYE No.44
Table:criterion of classification of
low vision and blindness(WHO,1973)
Best corrected vision
Best vision
lower than
1
2
Blindn 3
ess
4
5
Low
vision
0.3
0.1
0.05
0.02
Lowest vision equal to
or lower
0.1
0.05(FC/3m)
0.02(FC/1m)
Light perception
No light perception
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EYE No.45
several major ophthalmopathies
causing blindness
•
•
•
•
•
•
•
Cataract: the first cause
Keratopathy
Glaucoma
Trachoma
Eye injury and occupation ophthalmopathy
Genetic ophthalmopathy
Diabetic retinopathy
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