Cataract is a condition in which the lens of eye becomes cloudy. It is commonly seen in the old age.
If lens is cloudy, blurred image is seen. The patient experiences cloudy, double vision, sensitivity to light and difficulty seeing at night.
Epidemiology :-
- The WHO survey has shown that there is a backlog of over 22 million blind eyes (i.e. 12 million blind people ) in India. 80% of these are blind due to this disease.
- However, annual incidence of cataract blindness is about 3.8 million
- In adults, approximately 50% of visual impairment is over the age of 40.
Etiology :-
- Exact etiology is not known.
- Maternal malnutrition
- Maternal infection
- Heredity
- Foetal or infantile factors i.e. deficient oxygenation (anoxia), birth trauma.
Pathophysiology :-
• Proteins and fibers in the lens begin to breakdown, causing vision to become hazy or cloudy.
• Some inherited genetic disorders that cause other health problems can increase the risk of cataract.
Clinical features :-
- Blurred vision, diminished vision
- Seeing “haloes” around lights
- Fading or yellowing of colours
- Double vision in a single eye
- Increasing difficulty with vision at night
- White reflex in pupillary area (Leucocoria)
Classification :-
A. Etiological Classification-
- Congenital (developmental) cataract
- Acquired cataract
- Senile
- Traumatic
- Complicated
- Metabolic
- Electric
- Radiational
- Toxic
- Dermatogenic
B. Morphological classification-
- Capsular cataract –
- Anterior
- Posterior
- Subcapsular cataract
- Cortical
- Supranuclear
- Nuclear
- Polar
Types :-
- Nuclear cataract (Hard)
- Cortical cataract (Soft)
- Subcapsular cataract
- Anterior
- Posterior
Classification based on Degree of Maturity :-
- Mature – Lens completely opaque
- Immature – Lens partially opaque
- Hypermature – Liquefied cortical matter morgagnian cataract
Stages of Cortical Cataract :-
- Stage of lamellar separation=
- There is demarcation of cortical fibres owing to their separation by fluid which can be demonstrated on slit lamp examination. These changes are reversible .
- Stage of incipient cataract=
- Wedge shaped spokes of opacity with clear areas in between.
- Immature senile cataract=
- “Intumescent cataract” Progressive hydration causes swelling and opacification of lens. Lens appear greyish white but clear cortex is still present so iris shadow is visible.
- Mature senile cataract=
- Opacification becomes complete and lens become pearly white in colour.
- Hypermature senile cataract=
- When mature cataract is left untreated.
Signs and Symptoms :-
SIGNS:
- Visual acuity is reduced.
- Slit lamp examination allows the cataract to be examined in detail and site of opacity can be identified.
- Cataract appears black against the red reflex when the eye is examined with Direct Ophthalmoscope.
- Pigment deposition on lens suggesting previous inflammation.
SYMPTOMS:
- Painless loss of vison
- Glare – Intolerance to bright light
- Distortion of image
- Amblyopia (A failure of normal vision development)
- Monocular diplopia
- Coloured haloes
Diagnosis :-
- Oblique illumination examination.
- Visual acuity testing
- Distant direct ophthalmoscopic examination.
- Slit lamp examination.
Differential diagnosis :-
- Retinoblastoma
- Retinopathy of prematurity
- Persistant hyperplastic primary vitreous
- Glaucoma
- Refractive errors
Complications :-
- Endophthalmitis – Red eye, reduced visual acuity
- Iris prolapse
- Vitreous loss
- High intra-ocular pressure
- Retinal detachment
- Lens dislocation
Treatment :-
- Surgical procedures –
- Intracapsular lens extraction (ICCE)
- Extracapsular lens extraction (ECCE)
- ICCE – It involves extraction of the entire lens, including the posterior capsule.
- ECCE – It involves the removal of lens nucleus through an opening in the anterior capsule, with retention of integrity of posterior capsule.
Management :-
- Manual small incision cataract surgery (MSICS):- Basic principle is construction of a small, self-sealing sclero-corneal tunnel for delivery of the cataractous lens.
- Micro incision cataract surgery (MICS):-
- Approach to surgery through incision less than 1.8mm with the purpose of reducing surgical invasiveness.
- Phacoemulsification:-
- It is a modern surgery in which the eye’s internal lens is emulsified (broken) with an ultrasonic hand piece and aspirated from the eye.
- Aspirated fluids are replaced with irrigation of balanced salt solution to maintain the anterior chamber.
- Topical antibiotics:-
- Tobramycin and Gentamicin – 3 days before surgery (QID)
- Drugs for /to lower IOP
- Acetazolamide 500 mg stat 2hrs before surgery. Glycerol 60ml mixed with water 1hr before surgery.
- Drugs to sustain dilated pupil:- Antiprostaglandin eye drops.