4.lens and cataract

LENS AND CATARACT

ABIYE MULUGETA, MDAddis Ababa UniversityDepartment of Ophthalmology April, 2011

Objective- Know the normal anatomy and function of the lens.- Know the risk factors for the development of

cataract.- Know the sign and symptom of cataract.- Identify patients with cataract and be able to refer

patients to a centre where they can undergo definitive treatment i.e. surgery.

- Know the complications of untreated cataract.

Normal crystalline lens is transparent, biconvex structure.

It is derived from the surface ectoderm.It is composed of –capsule lens epithelium cortex and nucleusIt has no blood supply or nerve supply after fetal

development.

• Lies posterior to iris and anterior to vitreous.• Suspended in position by the zonular fiber.• It depends on aqueous humor to meet its

metabolic requirement and carry off its wastes.• It grows continuously throughout life.• Measures at birth adulthood• Equatorially 6.4mm 9mm.• Ap 3.5mm 5mm.• Weighs 90mg 255mg

• Functions -to maintain its own clarity. -provides accommodation. -to refract light, the lens contributes

about 15-20 diopters of the refractive power of the eye.

CATARACT• Any congenital or acquired opacity in the lens

or lens capsule is called as cataract

Epidemiology

1. Cataracts remain the leading cause of blindness.

2. Age-related cataract is responsible for 48% of world blindness, which represents about 18 million people

3. Cataracts are also an important cause of low vision in both developed and developing countries.

Cataracts

• Cataract surgery is the most frequently

performed surgical procedure • 50% of those over 65 develop vision impairing

cataracts.

CataractCauses

• Age• Congenital (genetic, metabolic)• Trauma• Uveitis• Metabolic• Surgery• Drugs (eg steroids)

SENILE CATARACT

CATARACT IN DOWN'S SYNDROME

Bilateral cataracts in an infant due to Congenital rubella syndrome

SENILE CATARACT

• Also called as age related cataract• Usually above the age of 50 yrs • Usually bilateral, but almost always one eye is affected earlier

than the other

CLASSIFICATION

Classified according to:Morphological Classification

• Nuclear• Cortical• Subcapsular

Maturity classification

• Immature Cataract • Mature Cataract • Hypermature Cataract

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Nuclear cataract• Most common type• Age-related• Occur in the center of the lens

NUCLEAR SENILE CATARACT

Congenital nuclear cataract

Cortical cataract • Occur on the outer edge of the lens (cortex).

• Begins as whitish, wedge-shaped opacities or streaks.

• It’s slowly progresses, the streaks extend to the center and interfere with light passing through the center of the lens.

• Problems with glare are common with this type of cataract.

CORTICAL SENILE CATARACT

Mature Cataract

• Lens is completely opaque.

• Vision reduced to just perception of light

Right eye mature cataract, with obvious white opacity at the centre of pupil

Hypermature Cataract

• This may take any of two forms:

1.Liquefactive/Morgagnian Type

2.Sclerotic Cataract

Liquefactive/Morgagnian Type

• Cortex undergoes auto-lytic liquefaction and turns uniformly milky white.

• The nucleus loses support and settles to the bottom.

Sclerotic Cataract

• The fluid from the cortex gets absorbed and the lens becomes shrunken.

• There may be deposition of calcific material on the lens capsule.

• The zonules become weak, increasing the risk of subluxation / dislocation of lens.

Symptoms

• A cataract usually develops slowly, so:

–Causes no pain.–Cloudiness may affect only a

small part of the lens–People may be unaware of any

vision loss.• Over time, however, as the

cataract grows larger, it:–Clouds more the lens–Distorts the light passing

through the lens.– Impairs vision

• Reduced visual acuity (near and distant object)

• Glare in sunshine or with street/car lights.

• Distortion of lines.

• Monocular diplopia.

• Altered colours ( white objects appear yellowish)

• Not associated with pain, discharge or redness of the eye

Symptoms of Cataracts

• Bright Colors Become Dull

• Halos Around Lights

Signs• Reduced vision, minimum LP• Only severe dense cataracts causing severely impaired vision

cause a white pupil.• Good pupillary reaction• Normal IOP

LENS AND CATARACT

ABIYE MULUGETA, MDAddis Ababa UniversityDepartment of Ophthalmology

April, 2011

Treatment

• Surgical removal.

• Surgical techniques

– Phacoemulsification method.

– Extracapsular method.

– Intracapsular method

• Surgical management Indications:- 1. visual improvement

2.Medical indications 3. Cosmetic indications

Before IOL implantation was developed

• Aphakic spectacles• Contact lenses

Pseudophakic eye

Phacoemulsification in cataract surgery involves insertion of a tiny, hollowed tip that uses high frequency (ultrasonic) vibrations to "break up" the eye's cloudy lens (cataract). The same tip is used to suction out the lens

.

Postoperative care after cataract surgery

• Steroid drops (inflammation)• Antibiotic drops (infection)• Avoid

• Very strenuous exertion (rise the pressure in the eyeball)• Ocular trauma.

Complications of cataract surgery• Infective endophthalmitis( infection)• Bleeding or haemorrhage• Uveatis( Inflammation)• Glaucoma• Vitreous loss• Cystoid macula• Retinal detachment . . .

Congenital Cataract• Occur in about 3:10000 live birth.• 2/3 of case are bilateral • It can cause ambylopia in infants.

Management in congenital cataract

• Bilateral congenital cataract require urgent surgery (lensectomy and vitrectomy) and the fitting of the contact lens to correct the aphakia

• Uniocular congenital cataract treatment remains controversial.

• Follow-up for children with congenital cataract should continue because of the risk for developing– Glaucoma– Amblyopia– Strabismus

Complications of untreated cataract- Blindness - Glaucoma- Uveitis- Subluxation and dislocation.

References

• Duanes clinical ophthalmology• BSCS• Albert and Jakcbeic• E-medicine

THANK YOU