2. LENS
Is a transparent structure immediately behind the iris, held in position by the
suspensory ligament ( zonule ), The zonule attaches the equator of the lens to
the ciliary body.
It is the second major refractive element of the eye, the cornea being the
first .
It Focuses light on the retina
Derived from ectoderm
It is avascular
It is highly elastic; but it hardens with age
Disease may affect structure, shape and position of the lens
3.
4.
5.
6. Cataract
Cataract is the name given to any light - scattering opacity within the lens
wherever it is located
It is the opacification of the lens of the eye
7. Classification
Classification of cataract according to the site:
1. Cortical(does not degrade vision very much)
2. Nuclear(Distance vision typically is affected much more than near vision)
3. Subcapsular (cause disabling glare in bright sunlight and from headlights)
4. Mix( the most common)
8.
9. Causes
Age related cataract
Childhood cataract
Traumatic cataract
Cataract secondary to intraocular disease
Cataract associated with systemic disease
Drug induced cataract
10. Age related cataract
Age - related cataract is commonly nuclear, cortical or subcapsular in
location
Age-related cataract is usually slowly progressive over years, and death may
occur before surgery becomes necessary. If surgery is indicated, lens
extraction improves visual acuity in over 90% of cases.
11.
12. Childhood cataract
Childhood cataracts are divided into two groups:
congenital (infantile) cataracts, which are present at
birth or appear shortly thereafter, and acquired
cataracts, which occur later and are usually related to a
specific cause
13. A. Congenital Cataract
Congenital lens opacities are common and often visually insignificant
requires no treatment other than observation for progression
Large, dense white cataracts may present as leukocoria (white pupil),
noticeable by the parents, but many dense cataracts cannot be seen by the
parents
Unilateral infantile cataracts that are dense, central, and larger than 2 mm in
diameter will cause permanent deprivation amblyopia if not treated within
the first 2 months of life
Bilateral cataracts may require less-urgent management, although bilateral
deprivation amblyopia can result from unwarranted delay
14. B. Acquired Cataract
Acquired cataracts often do not require the same urgent care(aimed at
preventing amblyopia) as infantile cataracts because the children are usually
older and the visual system more mature.
Because unilateral cataract in children will not produce any symptoms or
signs parents would routinely notice, screening programs are important for
case finding.
15. TRAUMATIC CATARACT
Traumatic cataract is most commonly due to a foreign body injury to the lens
or blunt trauma to the eyeball
The lens becomes white soon after the entry of a foreign body, since
interruption of the lens capsule allows aqueous and sometimes vitreous to
penetrate into the lens structure.
16.
17. CATARACT SECONDARY TO INTRAOCULAR
DISEASE (“COMPLICATED CATARACT”)
The cataract usually begins in the posterior subcapsular area and eventually
involves the entire lens structure. Intraocular diseases commonly associated
with the development of cataracts are chronic or recurrent uveitis, glaucoma,
retinitis pigmentosa, and retinal detachment. These cataracts are usually
unilateral. The visual prognosis is not as good as in ordinary age-related
cataract.
18. CATARACT ASSOCIATED WITH
SYSTEMIC DISEASE
Bilateral cataracts occur in many systemic disorders including diabetes
mellitus, hypocalcemia, myotonic dystrophy, atopic dermatitis, galactosemia,
and Down, Lowe (oculo-cerebro-renal), and Werner syndromes
19. DRUG-INDUCED CATARACT
Corticosteroids administered over a long period of time, either systemically or
in drop form, can cause lens opacities.
Other drugs associated with cataract include phenothiazines, amiodarone,
and strong miotic drops such as phospholine iodide.
Statin use, although data conflict about this association )due to up to date)
20. Secondary glaucoma
A small fraction of mature and hypermature cataracts can give rise to secondary
glaucoma
Phacolytic glaucoma, in which lysed lens proteins cause a pressure rise
Phacoanaphylactic glaucoma, in which the autoimmune reaction to these
proteins causes a pressure rise
Phacomorphic glaucoma, in which the swollen lens causes a form of angle
closure glaucoma
Morgagnian lens, a hypermature lens in which the lens nucleus has
fallen inferiorly
22. TREATMENT
The only treatment for cataract is to surgically remove and replace the opacified
lens from the eye to restore transparency of the visual axis.
Indications for surgery: Surgery is indicated if symptoms from the cataract
interfere with the patient's ability to meet his or her needs of daily living; there
are no criteria based upon the level of visual acuity.
23. Complications of Adult Cataract Surgery
The rarest, but also most serious complications include intraocular infection
(endophthalmitis, 0.1%) and intraocular hemorrhage (less than 0.5%), either
of which can result in severe visual loss
Other complications include retinal detachment, cystoid macular edema,
glaucoma, corneal edema, and ptosis.
The most common complication is posterior capsule opacification
