what is cataract and how it occurs.

Cataract

 It is the opacity of the lens of the eye causing partial or total visual loss

 The lens is made mostly of water and protein

    - The protein is arranged to let light pass through and focus on the retina

    - When the proteins clump together, they cloud small areas of the lens, blocking some light from reaching the retina and interfere with vision 

Causes of Cataract

1.Age related (Senile)

2.Ocular Conditions

•     Trauma   
•     Uveitis
•     High myopia
•     Topical medication (Steroid).
•     Intraocular Tumor

3.Systemic Causes

• Diabetes
• Metabolic disorders ( Galactosaemia, Hypocalcemia, Wilson’s ).
• Systemic Drug (Steroid, Chlorpromazine, Gold)
• Infection (TORCH)
• Myotonic dystrophy
• Atopic dermatitits
• Congenital (inherited) cataract.
• X-radiation

Cataract - Symptoms

•  Painless blurring or dimming of vision
•  Glare and Sensitivity to light[esp. in bright sunlight or while driving at night]
•  diplopia
•  Changes in refractive error - requiring frequent changes in your eyeglass prescription

Signs of Cataract

•  Reduced visual acuity.
•  Black shadow against the red reflex when the eye is examined with direct ophthalmoscope.
•  Leukocoria (white pupillary reflex)

Examination of cataract

• Vision (BCVA)
• Lid and adnexal examination (infection, deformity)
• Pupil light reflex (RAPD)
• Distance direct ophthalmoscopy (examination of red reflex).
• Tonometry (IOP)
• Dilated Fundoscopy (Cause of dec. vision)
• Biometry (IOL Calculation)

Types of Cataract (Morphological)

• Nuclear sclerosis.
• Anterior Sub capsular cataract.
• Posterior Sub capsular cataract.
• Cortical cataract

Types of Cataract (Clinical)

 Immature cataract
    - A cataract that still allows view of the posterior pole and transmits a red reflex
 Mature cataract
    - once the red reflex is loss, it becomes mature
Hypermature Morgagnian cataract
       -Subluxated cataractus lens 

cataract surgery

Indications for Cataract Surgery

Reduced visual acuity sufficient to interfere with a patient’s desired activities

Cataract sufficiently dense to obscure fundus diagnosis and management (e.g. in diabetic retinopathy)

Complications of cataract (e.g. lens induced glaucoma)

Types of Cataract Surgery

1. Intracapsular Cataract Extraction (ICCE)

Removal of whole lens thru. Large limbal incision , including the capsule

Obsolete nowadays

2. Extracapsular Cataract Extraction (ECCE)

            - Removal of lens nucleus and cortex through an opening in the anterior capsule, leaving the posterior capsule in place for IOL implantation. 2 types:

   a. Conventional ECCE – Large limbal incision

   b.      Phaco-emulsification

            - the lens nucleus is emulsified using ultrasound thru. a small limbal incision

Visual Rehabilitation after Cataract Extraction

• Intraocular lens (IOL)
• Spectacles
• Contact lenses

Complications of Cataract Surgery

Operative Complications:

• Rupture of posterior capsule
• Dropped nucleus
• Supra choroidal hemorrhage

Early Post operative complications:

• Keratitis
• Wound leakage
• Iris prolapse
• Secondary glaucoma
• Hyphema
• Decentered IOL
• Cystoid macular edema
• Endophthalmitis

Late Post operative complications:

• Posterior Capsular Opacification
• Retinal Detachment
• Refractive Error

Congenital Cataract

Causes:

• Genetic (Autosomal dominant)
• Birth trauma
• Maternal infection    (TORCH)
• Metabolic disorders (Galactosemia, hypocalcemia, hypoglycemia)
• Chromosoal disorders (Lowe syndrome,Down’s)

                                                                       

Investigations

• Serological test for TORCH
• Urinalysis for reducing substance
• Urine for chromatography of amino acid for lowes syndrome
• Fasting blood sugar
• Serum Calcium
• Chromosomal analysis