Opacity of lens leading to visual impairment is called Cataract.

Visual Impairment depends on….

1. Density of opacity

     2. Location of the opacity

Blindness due to cataract always reversible
Blindness due to optic nerve is irreversible

Causes Of Cataract

1. Congenital (Cataract at child birth)
a. Rubella
      b. Syphilis
    c. Some infective disease
2. Developmental cataract (After birth but before senile age)
3. Age related cataract (Senile cataract)
            In BD                      : At 50 years
            In western countries : After 60 years   
4. Traumatic cataract
5. Complicated cataract
      It is secondary to interocular disease.
           a. Uveitis (Inflammation of uveal tract)
            b. Scleritis
            c. Pathological myopia
            d. Long standing retinal attachment 
6. Cataract due to systemic diseases
    a. DM
      b. Scleroderma
      c. Atopic dermatitis 
7. Drugs – Corticosteroids

Morphological Types / Causes Of Age Related Cataract

1. Nuclear cataract 
2. Cortical cataract
a. Anterior cortical cataract
b. Posterior cortical cataract
c. Equatorial cortical cataract
3. Capsular cataract
  a. Anterior capsular cataract
b. Posterior subcapsular cataract

Grading Of Nuclear Cataract

On the basis of colour changes of nucleus
1. Grade I : Grayish white 
2. Grade II : Yellowish white  
3. Grade III : Yellow 
4. Grade IV : Yellowish brown  
5. Grade V : Brown colour (Brunescent cataract)

Stages Of Age Related Cataract

On the basis of visual impairment & lens colour
Stage I   : Immature
Visual acquity is reduced to counting fingers 
Lens colour : Greyish white

Stage II  : Mature
Visual acquity is reduced to hand movement
Lens colour : Dense white

Stage III : Intumescent cataract
Swelling of the lends due to hydration of lens fibres
This increases the anterioposterior diameter of the lens
It can occur in mature / immature stage
Lens colour : Greyish white
Complications : Secondary closed angle glucoma (as it blocks the pupil)
Stage IV : Hypermature 
Visual acquity is reduced to perception of light
Lens colour :  Milky white
Degeneration of lens capsule

Leakage of lens fibres

Shrinkage of lens capsule due to reduced volume of lens 

Stage V  : Morgagnian
Visual acquity is reduced to perception of light
Lens colour :  Milky white
Total liquifaction of the lens cortex
Nucleus will be deplaced downwards 

Management Of Age Related Cataract

A. Medical 
There is no proven medical treatment for cataract
In the initial stage, vision may be improved with spectacle correction 
B. Surgical 
It is the only method to improve the vision

Indications Of Surgery In Cataract

1. If the patient is handicap to his/her profession
2. Medical indications
a. Lens induced glucoma
I.  Phacolytic glucoma        
  II. Phacomorphic glucoma 
  b. Phacoantigenic uveitis
3. To diagnose & treat diabetic retinopathy
When there is cataract, it is difficult to evaluate the status of the retina
4. In case of monopolar cataract to improve binocular vision / visual acquity
5. Cosmetic purpose
Cataract with optic nerve damage / retinal damage 
Vision will not be improved with the removal of cataract
There is only cosmetic advantage 

Surgical Techniques

1. Couching
2. ICCE : Intracapsular cataract extraction
3. ECCE : Extracapsular cataract extraction
4. SICS : Small incision cataract surgery 
5. Phacoemulsification
6. Laser cataract surgery

Complications Of Cataract Surgery

A. Anaesthetic complications 
1. Optic nerve damage
2. Brain stem anaesthesia
3. Globe perforation 
4. Retrobulbar haemorrhage
5. Subconjuctival haemorrhaeg
6. Chemosis
B. Perioperative complications
1. Posterior capsular rent
2. Vitreous loss
3. Damage to corneal endothelium
4. Detachment of basement membrane 
C. Posterior complications 
a. Immediate
1. Corneal oedema
2. Striae 
3. Iris prolapse
4. Shallow anterior chamber
5. Acute postoperative endophalmitis  
b. Late 
1. Cystoid macular oedema (CMO)
2. Posterior capsule opacification
3. Retinal detachment
4. IOL decentration

Types Of Intraocular Lens

A. According to the position
1. Anterior chamber IOL
It is situated infront of the iris
2. Posterior chamber IOL
It is situated behind of the iris
B. According to the material 
1. Rigid IOL
a. Polymethyl-methacrylate (PMMA) IOLs
2. Foldable IOL
a. Silicon IOLs
b. Hydrophilic acrylic IOLs
c. Hydrophobic acrylic IOLs
C. According to the function
Types of foldable IOL
1. Aspheric foldable IOL : Enhance contrast sensitivity
2. Tonic IOL : Correction of both pre-existing astigmatism & surgically   induced astigmatism
3. Presbyopia correcting IOL : Correct both distant & near vision
    (Multifocal IOL)

All IOL except mutifocal IOLs need near corrections for near vision, because….
As IOL has no accommodation power
As IOL is not elastic

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