CATARACT

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CATARACT
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OBJECTIVES

1. ANATOMY
2. DEFINITION AND EPIDIMIOLOGY
3. CAUSES
4. SYMPTOMS AND SIGNS
5. DDx OF GRADUAL LOSS OF VISION
6. TREATMENT
7. PRE-OPERATIVE ASSESMENTS
8. COMPLICATIONS
9. POST-OP care
10. CONGENITAL CATARACT

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The lens

• Its crystalline.
• Histology
• Capsule
• Subcapsular epithelium (simple cuboidal).
• Synthesize protein for lens fiber
• Transport AA
• Maintains a cation pump to keep the lens clear
• Lens fibers
• Cross section
• Capsule
• Cortex
• nucleus

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• Functions of lens
• Refraction
• Accounts for 35 of total refractive
  power of eye (15D out of total of 58D)
• Light transmission

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• Maintenance of transparency
• Avascular
• Regular arrangement of lens fibers
• Semipermeable character of lens capsule
• Pump mechanism of lens fibre membranes that
  regulate the electrolyte and water balance in the
  lens, maintaining relative dehydration and
• Auto-oxidation and high concentration of reduced
  glutathione in the lens maintains the lens
  proteins in a reduced state and ensures the
  integrity of the cell membrane pump.

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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.

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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.

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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
• Marfans syndro
• High myopia

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Cataract

• Divided to
• Acquired cataract
• Age - related cataract
• Traumatic cataract
• Metabolic - DM
• Drug induced cataract- Steroid
• Secondary cataract- Uveitis, ACG
• Congenital Cataract
• Systemic association
• Non-systemic association

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Age -related cataract

• It is the Most commonly occurred.
• 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
• 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.
• As the cataract progresses, the lens may even
  turn brown.

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Cortical cataract

• Occur on the outer edge of the lens (cortex).
• Begins as whitish, wedge-shaped opacities or
  streaks.
• Its 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.

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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.
• Its interferes with reading vision
• Reduces vision in bright light
• Causes glare or halos around lights at night.

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Posterior Subcapsular Cataracts

• Begins at the back of the lens (posterior pole)
  spreads to the periphery or edges of the lens.
• 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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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
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Hypermature Cataract

• Shrunken and wrinkled anterior capsule due to
  leakage of water out of the lens.
• This may take any of two forms
• Liquefactive/Morgagnian Type
• Sclerotic Cataract

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Liquefactive/Morgagnian Type

• Cortex undergoes auto-lytic liquefaction and
  turns uniformly milky white.
• The nucleus loses support and settles to the
  bottom.

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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.

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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

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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.

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Gradual loss of vision

• DDX
• Cataract
• Glaucoma
• Diabetic retinopathy
• Hypertensive retinopathy
• Age related macular degeneration
• Retinitis pigmentosa
• Trachoma
• Onchocerciasis (river blindness)
• Vitamin A deficiency

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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

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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.

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Postoperative care after cataract surgery

• Steroid drops (inflammation)
• Antibiotic drops (infection)
• Avoid
• Very strenuous exertion (rise the pressure in the
  eyeball)
• Ocular trauma.

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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.

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• Uveitis
• Ocular perforation.
• Postoperative refractive error
• Posterior capsular rupture and vitreous loss

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• 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.

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Congenital Cataract

• Occur in about 310000 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
• Systemic association
• Non-systemic association

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Systemic association

• Metabolic
• Galactosaemia, galactokinase deficiency, Lowe
  syndrome, others (hypoparathyroidism,
  pseudohypoparathyroidism, mannosidosis)
• Prenatal infection
• Congenital rubella (15 of cases), other
  intrauterine infection (toxoplasmosis,
  cytoegalovirus, herpes simplex varicella)
• Chromosomal Abnormalities
• Down syndrome5
• Patau (trisomy 13)
• Edward (trisomy 18 ) syndrome.

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• Bilateral cataracts in an infant due to
  Congenital rubella syndrome

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Non-systemic association

• 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

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Zonular cataract
The lens opacities (riders) are located in only
one layer of lens fibers, often only in the
equatorial region as shown here.
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Congenital anterior polar cataract and persistent
pupillary membrane
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1. Coronary (supranuclear) cataract round opacities
   in deep cortex surrounding nucleus like crown.
2. Blue dot cataract (cataracta punctata caerula)
   common and innocuous, may coexist with other type
   of lens opacities
3. Total (mature) cataract frequently bilateral and
   often begin as lamellar or nuclear
4. Membranous cataract (rare)

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Nuclear cataract
This variant of the lamellar cataract affects
only the outer layer of the embryonic nucleus,
seen here as a sutural cataract.
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Congenital nuclear cataract
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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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What is the pathophysiology of diabetic cataracts?

• 1. Osmotic effect
• Glucose sorbitol via aldose reductase (rapid)
  fructose via polyol dehydrogenase (slow)
• Sorbitol cannot diffuse out of intracellular
  compartment accumulates in lens creates an
  osmotic gradient with movement of water into
  cells swelling and rupture of cells
  opacification and cataract formation

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• 2. Direct damage
• Glucose may directly interact with lens proteins
  by glycosylation, leading to protein aggregation
  and cataract formation

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Management of diabetic cataract

• Management is the same as senile cataract

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