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Definition :
Cataract is simply defined as opacity developed in the lens or its capsule.
Transparency of the lens is maintained by the regular arrangement of lens fibers.
Hence, it occurs either through the formation of opaque lens fibers or any degenerative process that leads to opacification of normal transparent lens fibers
Classification :
ETIOLOGICAL
Firstly, Congenital
Secondly, Acquired
Senile
Traumatic
Complicated
Metabolic
Electric
Radiational
Toxic cataract, e.g.
i. Corticosteroid-induced,
ii. Miotics-induced,
ii. Copper and iron induced
Associated with skin diseases
Associated with osseous diseases
Associated with miscellaneous syndromes, e.g.
i. Dystrophica myotonica
ii. Down’s syndrome
iii. Lowe’s syndrome
iv. Teacher-Collin’s syndrome.
MORPHOLOGICAL
Capsular cataract
i. Anterior capsular
ii. Posterior capsular
Subcapsular cataract
i. Anterior subcapsular
ii. Posterior subcapsular
Cortical cataract
Supra nuclear cataract
Nuclear cataract
Polar cataract
i. Anterior polar
ii. Posterior polar
CONGENITAL:
Present at time of birth or may develop later.
Congenital- present at time of birth; embryonic or fetal nucleus affected.
Developmental– develops between infancy and also adolescence; infantile or adult nucleus affected.
Etiology :
Idiopathic
Hereditary
Without systemic disorders (AD inheritance)
With systemic disorders-Downs syndrome
Maternal factors
Malnutrition during pregnancy
Infections
Drug intake- thalidomide, steroids
And also radiation exposure
Fetal factors
Anoxia
Birth trauma
Metabolic disorder
Cataracts associated with other congenital anomalies
Ocular diseases associated with developmental type
And also Malnutrition
CONGENITAL CAPSULAR CATARACT :
Anterior Capsular cataract
Delayed formation of anterior chamber.
Underlying cortex may become opaque
Posterior Capsular cataract
Persistence of posterior part of vascular sheath- hyaloid artery
POLAR CATARACT
Anterior polar cataract
Involves central part of anterior capsule; due to delayed development or corneal perforation
Posterior polar cataract
Small circular opacity involving the posterior pole
CONGENITAL NUCLEAR CATARACT- ZONULAR CATARACT
MCC of congenital type presenting with vision defect
Etiology-
hereditary-AD type
Vit D deficiency or hypocalcemia
Characteristics:
Fetal nucleus affected
Usually bilateral and causes vision defect
Wheel-spoke opacity seen
Two such rings of opacity seen
GENERALIZED CATARACT :
Coronary cataract
Common during puberty- adolescent nucleus involved
Opacities- regular radial distribution
Large punctate opacities may marginally reduce vision
60% by the age of 60 years, 70% by the age of 70 years, 80% by the age of 80 years, and 90% by the age of 90 years develop senile type.
2. Secondly, Sex. Greater in females than males at all ages.
3. Thirdly, Heredity
4. Ultraviolet irradiations
5. Dietary deficiency
6. Dehydrational crisis in childhood
7. And also Smoking
MECHANISM
Cortical senile cataract :
decreased levels of lens protein, amino acids and potassium + increased concentration of sodium + hydration of the lens followed by coagulation
Soft lens formed
Nuclear senile cataract :
Increase in water soluble protein+dehydration and also compactation of lens
Finally, Hard lens formed
A. Maturation of the cortical type of senile cataract
1. Stage of lamellar separation
Formation of vacuoles and also water clefts leads to demarcation of cortex.
Moreover it is a Reversible process.
2. Stage of incipient cataract
Two distinct types of senile cortical cataracts can be recognized at this stage:
a. Cuneiform senile cortical cataract
Wedge-shaped opacities. Seen first in the lower nasal quadrant. Starts at periphery and extends centrally, therefore vision affected late
b. Cupuliform senile cortical cataract.
Saucer-shaped opacity gradually extends outwards. Lies right in the pathway of the rays and thus causes early vision loss
3.Immature senile cataract-
opacification progresses further. Lens appears greyish white Iris shadow is visible. lens may become swollen due to continued hydration. This condition is called ‘intumescent cataract’.
4.Mature senile cataract (MSC)
Opacification complete. Lens becomes pearly white. Also called as ‘ripe cataract’
B. Maturation of nuclear senile cataract
Progressive nuclear sclerotic process- decreases ability to accommodate and also obstructs the light rays.
Finally these changes begin centrally and then spread peripherally when it becomes mature
Clinical features :
SYMPTOMS
Firstly, Glare
Secondly, Uniocular diplopia
Thirdly, Colored halos
Floaters
Blurry and also slow detoriation of vision
SIGNS
Complications :
Phacoanaphylactic uveitis
And also Lens-induced glaucoma
Diabetic cataract :
l. Senile type in diabetics- appears at an early age and also progresses rapidly.
2.True diabetic /snowflake/snowstorm cataract occurs in young adults due to osmotic overhydration of the lens-sorbitol accumulates.
Fluid vacuoles appear underneath the anterior and posterior capsules which leads to bilateral snowflake-like white opacities in the cortex.
May resolve spontaneously or mature within a few days.
Complicated cataract :
Secondary to a disease
1. Inflammatory conditions
uveal inflammations- iridocyclitis, pars planitis, choroiditis MCC-anterior uveitis
Hypopyon corneal ulcer
Endophthalmitis
2. Degenerative conditions-
Retinitis pigmentosa and other pigmentary retinal dystrophies and also myopic chorioretinal degeneration.
3. Retinal detachment
4. Glaucoma
5. Moreover lntraocular tumours like retinoblastoma or melanoma also leads to complicated type.
Management of Cataract :
A. NON-SURGICAL MEASURES :
1. Treatment of cause:
Firstly, Control of DM
Removal of cararactogenic drugs- corticosteroids, phenothiazines and strong miotics
And also Removal of radiation
2.Delay progression:
Topical preparations containing iodide salts of calcium and also potassium
Vitamin E and also aspirin delay cataractogenesis
3.Measures to improve vision
Prescription of glasses for refractive status
Arrangement of illumination
Use of dark goggles
And also Mydriatics
B. SURGICAL MANAGIEMENT:
I Preoperative evaluation
Ocular examination
slit-lamp biomicroscopy
fundoscopy
Visual acuity should be noted- Perception of light (PL) and also Projection of light rays (PR) must be noted.
2. Pupils:
• Light reactions and RAPD, and also
• Ability of the pupils to dilate adequately before surgery.
3 . Anterior segment evaluation by slit-lamp
Cornea
KP
Cataractous lens
Other signs to be particularly looked for include posterior synechiae, pseudoexfoliation, iridodonesis, pigments over the anterior lens capsule, and also anterior chamber depth.
4 . Intraocular pressure (IOP) should be measured
5. Examination of lids, conjunctiva and lacrimal apparatus.
6. Fundus examination
7. Retinal/ Macular function tests
• Two-light discrimination test
• Maddox rod test
• Colour perception
• Entoptic visualization
8. Objective test for evaluating retina -ultrasonic geographic (USG), ERG (electroretinogram), EOG (electrooculogram) and VER (visually evoked response)
9. Keratometry, corneal topography and also biometry to calculate power of intraocular lens (IOL)
II. General medical examination of the patient
Check for systemic diseases
1.Firstly, Consent to be obtained
2.Scrub bath.And also the eye to be operated should be marked.
3.Preoperative antibiotics and also disinfectants are required to prevent postoperative endophthalmitis:
• Topical antibiotics-fluoroquinolone
• Povidone-Iodine (10%) topical solution
• Povidone-Iodine (5%) solution instilled as eye drops
4. IOP lowering- mechanical pressure and / or by IOP lowering drugs-mannirol or acetazolamide
5. Mydriasis sustained by:
• Topical tropicamide + Phenylephrine 2.5% every 4-6 minutes
• Topical cyclooxygenase inhibitor (NSAID) td before the surgery
Eg. Ketorolac
Types of surgical procedures :
I. lntracapsular cataract extraction (ICCE)
The cataractous lens with the intact capsule is removed
Indication– markedly subluxated and dislocated lens.
II. Extracapsular cataract extraction (ECCE)
Major portion of anterior capsule with epithelium, nucleus and also cortex are removed; leaving behind the intact posterior capsule.
Contraindication– markedly subluxated or dislocated lens.
Advantages of ECCE techniques
1. ECCE can be performed at all ages, ICCE cannot be performed below 40 years of age.
2. Posterior chamber IOL can be implanted after ECCE, while it cannot be implanted after ICCE.
3. Postoperative vitreous related problems associated with ICCE are not seen after ECCE.
4. Incidence of postoperative complications are much less after ECCE
5. Postoperative astigmatism is less with ECCE as the incision is smaller.
6. Moreover, Incidence of secondary rubeosis in diabetics is reduced after ECCE.
Different techniques ofECCE :
Firstly, Conventional ECCE,
Secondly, Manual small incision cataract surgery (SICS),
Thirdly, Phacoemulsification,
And also Femtosecond laser assisted cataract surgery (FLACS).
Postoperative management :
l. Firstly, Patient is asked to lie quietly for about 2- 3 hours
2.Secondly, Diclofenac sodium may be given orally for mild to moderate postoperative pain.
3.Thirdly, Bandage/ eye patch is removed next morning and eye is inspected for any postoperative complication.
4.Antibiotic eye drops 4x for 10-14 days.
5.Topical steroids (Prednisolone) eye drops 3x for 6-8 weeks.
6.Topical ketorolac or any other NSAID eye drops 2x for 4 weeks.
7.Topical cycloplegic-mydriatic, e.g. homatropine eye drops OD for 10- 14 days.
8.Moreover Spectacles are prescribed after about 6-8 weeks of SICS operation and 3-4 weeks of phacoemulsification.
9.Finally, Topical timolol (0.5%) eye drops 2x for 5-7 days.
