CATARACT

DONE BYJony Mallik

CATARACT SEMINAR OBJECTIVES

1. ANATOMY OF THE LENS2. DEFINITION AND EPIDIMIOLOGY3. CAUSES4. AGE RELATED CATARACT 5. SYMPTOMS AND SIGNS6. DDx OF GRADUAL LOSS OF VISION7. TREATMENT8. PRE-OPERATIVE ASSESMENTS9. COMPLICATIONS10. POST-OP care11. CONGENITAL CATARACT

The lensIt’s crystalline.Histology:1. Capsule2. Subcapsular epithelium (simple cuboidal).• Synthesize protein for lens fiber• Transport AA• Maintains a cation pump to keep the lens clear

3. Lens fibers

Cross section:1. Capsule2. Cortex3. nucleus

Ciliary muscle•Innervation: 3rd CN•Function:• Constricts ciliary body• Relaxes tension on lens• Lens become spherical,

which increase the refractive power

Ciliary process•Attaches to the lenses by suspensory ligament (zonular fibers)•Secrete the Aqueous humor into the post. chamber

Definition of cataract• Opacity of the lens, which occurs when fluid gathers between

the lens fibers.When eyes work properly:• Light passes through the cornea and the pupil to the lens.• The lens focuses light & producing clear, sharp images on the

retina.• As a cataract develops, the lens becomes clouded, which

scatters the light and prevents a sharply defined image from reaching retina. As a result, vision becomes blurred.

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.

Causes of cataract• Old age (commonest)• Ocular & systemic diseases

– DM– Uveitis– Previous ocular surgery

• Systemic medication– Steroids– Phenothiazines

• Trauma & intraocular foreign bodies

• Ionizing radiation– X-ray– UV

• Congenital– Dominant– Sporadic– Part of a syndrome– Abnormal galactose

metabolism– Hypoglycemia

• Inherited abnormality– Myotonic dystrophy– Marfan’s syndrom– Rubella– High myopia

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Cataract

Divided to :

• Acquired cataract

Age - related cataract

Presenile cataract

Traumatic cataract

Drug induced cataract

Secondary cataract

• Congenital Cataract

Systemic association

Non-systemic association

Age -related cataract It is the Most commonly occurred.

Classified according to:Morphological Classification

• Nuclear• Cortical• Subcapsular• Christmas tree – uncommon

Maturity classification

• Immature Cataract • Mature Cataract • Hypermature Cataract

Nuclear cataract• Most common type• Age-related• Occur in the center of the lens.• In its early stages, as the lens changes the way

it focuses light, patient may become more nearsighted or even experience a temporary improvement in reading vision. Some people actually stop needing their glasses.

• Unfortunately, this so-called 2nd sight disappears as the lens gradually turns more densely yellow & further clouds vision.

• As the cataract progresses, the lens may even turn brown. Advanced discoloration can lead to difficulty distinguishing between shades of blue & purple.

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.

Subcapsular cataract

• Occur just under the capsule of the lens.

• Starts as a small, opaque area

• It usually forms near the back of the lens, right in the path of light on its way to the retina.

• It’s interferes with reading vision

• Reduces vision in bright light

• Causes glare or halos around lights at night.

Posterior Subcapsular Cataracts• Begins at the back of the lens (posterior pole) & spreads to the

periphery or edges of the lens.

• It can be developed when:

– Part of the eye are chronically inflamed.

–Heavy use of some medications (steroids).

• Affects vision more than other types of cataracts because the light converges at the back of the lens.

• Anything constrict the pupils (bright light) makes it very difficult for people with this type of cataract to see.

• Dilating drops useful in this type by keeping the pupils large and thus allow more light into the eye.

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Immature Cataract Lens is partially opaqueTwo morphological forms are seen:1.Cuneiform Cataract:– Wedge shaped opacities in the peripheral cortex and

progress towards the nucleus.– Vision is worse in low ambient illumination when the pupil

is dilated.2.Cupuliform Cataract:– A disc or saucer shaped opacities beneath the posterior

capsule.– Vision is worse in bright ambient illumination when the

pupil is constricted. Lens appears grayish white in color.Iris shadow can be seen on the opacity with oblique illumination.

Mature Cataract

• Lens is completely opaque.

• Vision reduced to just perception of light

• Iris shadow is not seen

• Lens appears pearly white

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

Hypermature Cataract

• Shrunken and wrinkled anterior capsule due to leakage of water out of the lense.

• 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.

• Iridodonesis: Anterior chamber deepens and iris becomes tremulous.

• 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

Signs• Reduced acuity.• An abnormally dim red reflex is seen when the eye is viewed

with an ophthalmoscope.• Reduced contrast sensitivity can be measured by the

ophthalmologist.• Only sever dense cataracts causing severely impaired vision

cause a white pupil.• After pupils have been dilated, slit lamp examination shows

the type of cataract.

Gradual loss of visionDDX:1. Cataract2. Glaucoma3. Diabetic retinopathy4. Hypertensive retinopathy5. Age related macular degeneration6. Retinitis pigmentosa7. Trachoma8. Onchocerciasis (river blindness)9. Vitamin A deficiency

Treatment

• Glasses: Cataract alters the refractive power of the natural lens so glasses may allow good vision to be maintained.

• Surgical removal: when visual acuity can't be improved with glasses.

• Surgical techniques

– Phacoemulsification method.

– Extracapsular method.

– Intracapsular method

Pre-op assesments• General health evaluation including blood pressure check• Assessment of patients’ ability to co-operate with the

procedure and lie reasonably flat during surgery• Instruction on eye drop instillation• The eyes should have a normal pressure, or any pre-existing

glaucoma should be adequately controlled on medications.• An operating microscope is needed, in order to reach the lens,

a small corneal incision is made close to the limbus for the phaco-probe.

• It is important to appreciate anterior chamber depth and to keep all instruments away from the corneal endothelium in the plane of the iris.

Phacoemulsification:1. Corneal incision 2.75-3.2 mm2. Viscoelastic to anterior chamber.3. Capsulorhexis4. Hydrodissection.5. Phacoemulsification of the nucleus.6. Aspiration of the cortex.7. More viscoelastic.8. Folded intraocular lens (IOL) is inserted under a cushion of

viscoelastic fluid which protect the corneal endothelium, the lens unfold spontaneously within the capsular bag.

9. Vescicoelastic removed and replaced with balanced salt solution.

10. Self sealing wound.

11. Sub conjunctival injection of steroid and antibiotics

12. Eyepad and protection eye shield.

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

.

Extra-capsular Cataract Extraction (ECCE)

• The nucleus and the cortex is removed out of the capsule leaving behind:

• Intact posterior capsule

• Peripheral part of the anterior capsule

• Zonules.

• This method:

• Provides support of placement of IOL

• Prevents vitreous from bulging forwards

• Acts as a barrier between anterior and posterior segment.

• All this results in decreasing the incidence of complications.

Intra-capsular Cataract Extraction

• The lens is removed as one single piece i.e., the nucleus and the cortex are removed within the capsule of the lens after breaking the zonules.

• There is no support left for posterior chamber IOL, therefore, only anterior chamber IOL (ACL) can be implanted which has risk of adverse corneal complications.

• There is no barrier left between anterior and posterior segment, which increases the incidence of other complications.

• The only advantage is that after-cataract does not develop as the entire capsule is removed.

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

– Rare but can cause permanent severe reduction of vision.– Most cases within two weeks of surgery.– Typically patients present with a short history of a reduction in their

vision and a red painful eye.– This is an ophthalmic emergency.– Low grade infection with pathogen such as Propionibacterium species can

lead patients to present several weeks after initial surgery with a refractory uveitis

• Suprachoroidal haemorrhage.– Severe intraoperative bleeding can lead to serious and permanent

reduction in vision.

• Uveitis– Postoperative inflammation is more common in certain types of eyes for

example in patients with diabetes or previous ocular inflammatory disease.

• Ocular perforation.

• Postoperative refractive error– Most operations aim to leave the patient emmetropic or slightly myopic, but

in rare cases biometric errors can occur or an intraocular lens of incorrect power is used.

• Posterior capsular rupture and vitreous loss– If the very delicate capsular bag is damaged during surgery or the fine

ligaments (zonule) suspending the lens are weak (for example, in pseudoexfoliation syndrome), then the vitreous gel may prolapse into the anterior chamber. This complication may mean that an intraocular lens cannot be inserted at the time of surgery. Patients are also at increased risk of postoperative retinal detachment.

• Retinal detachment.– This serious postoperative complication is, fortunately rare, but is

more common in myopic patients after intraoperative complications.

• Cystoid macular oedema– Accumulation of fluid at the macula postoperatively can reduce the

vision in the first few weeks after successful cataract surgery. In most cases this resolves with treatment of the post-operative inflammation.

• Glaucoma– Persistently elevated intraocular pressure may need treatment

postoperatively.

• Posterior capsular opacification– Scarring of the posterior part of the capsular bag, behind the

intraocular lens, occurs in up to 20% of patients. Laser capsulotomy may be needed.

Congenital Cataract• Occur in about 3:10000 live birth.• 2/3 of case are bilateral (half of the cause can be identified)• The most common cause is genetic mutation usually AD• It can cause ambylopia in infants.• It is divided to:

1. Systemic association2. Non-systemic association

Systemic association

1. Metabolic:• Galactosaemia, galactokinase deficiency, Lowe

syndrome, others (hypoparathyroidism, pseudohypoparathyroidism, mannosidosis)

2. Prenatal infection:• Congenital rubella (~15% of cases), other

intrauterine infection (toxoplasmosis, cytoegalovirus, herpes simplex varicella)

3. Chromosomal Abnormalities:• Down syndrome~5%• Patau (trisomy 13)• Edward (trisomy 18 ) syndrome.

Bilateral cataracts in an infant due to Congenital rubella syndrome

Non-systemic association

1. Isolated hereditary cataract About 25% of cases. Most frequently AD, but maybe AR or X-linked Better visual prognosis than coexisting ocular and

systemic abnormalities Classified to:

Zonular cataract: opacity occupies a discrete zone in the lens

Polar cataract: opacities occupy subcapsular cortex at anterior or posterior pole of lens

Zonular cataract

The lens opacities (“riders”) are located in only one layer of lens fibers, often only in the equatorial region as shown here.

Congenital anterior polar cataract and persistent pupillary membrane

2. Coronary (supranuclear) cataract: round opacities in deep cortex surrounding nucleus like crown.

3. Blue dot cataract (cataracta punctata caerula): common and innocuous, may coexist with other type of lens opacities

4. Total (mature) cataract: frequently bilateral and often begin as lamellar or nuclear

5. Membranous cataract (rare)

Nuclear cataract

This variant of the lamellar cataract affects only the outer layer of the embryonic nucleus, seen here as a sutural cataract.

Congenital nuclear cataract

Management in congenital cataract

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

• After the age of 2 years there is a general agreement to use intraocular lenses (IOLs), but before is still controversial

• Uniocular congenital cataract treatment remains controversial.

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

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