Cataract associated with ocular diseases:
Complicated Cataract : is due to disturbance of the nutrition of lens due to inflammatory or degenerative disease of anterior and /or posterior segment of the eye like iridocyclitis, cilitis, pars planitis, choroiditis, myopic degeneration, retinitis pigmentosa, retinal detachment, other retinal pigmentory dystrophies etc.
► A non-descript opacity develops in cortex which usually progresses and mature.
► In inflammatory or degenerative condition of posterior segment, opacification usually starts in the posterior part of the cortex in the axial region (posterior cortical cataract or posterior subcapsular cataract)
► Cataract has characteristic breadcrumb appearance and rainbow display of colours (polychromatic lustre). Cataract may remain stationary in posterior cortex or progress to involve the whole posterior cortex and entire lens. Cataract is usually soft and uniform in appearance.
► Vision is usually affected even in early stages as opacity is near the nodal point of the eye.
Prognosis depends on the causative condition.► All cases of cataract without obvious cause should be carefully looked for keratic precipitates or evidences of pars planitis.
Cataract associated with systemic disease
► Diabetic Cataract:Early onset of senile cataract and cataract develops rapidly.
True diabetic cataract is rare condition, occurring typically in young people with acute diabetes (with gross imbalance of water balance of the body). Fluid droplets (vacuoles) appear under the anterior and posterior subcapsular cortex, manifesting as myopia, producing diffuse opacity. These changes are reversible.
► The lens rapidly becomes cataractous with dense, white anterior and posterior subcapsular cortical cataract resembling snowstorm “snowflake Cataract”.
► If diabetes is controlled appropriately, the rapid progression to mature cataract may be arrested.
► Parathyroid Tetany
► Myotonic Dystrophy
► Down Syndrome
► Atopic Cataract
Objective Examination► The state of the nucleus (grading of nuclear sclerosis)
► The state of the cortex
► The presence or absence of signs of inflammation
► Pupillary glow by transillumination
► B- Scan ultrasonography
Functional Tests► Pupillary reaction
► Projection of light
► Macular function test – two pinholes test and Maddox rod test
► Entoptic view of the retina : Auto-ophthalmoscopy
► Electro-retinographic record, particularly of macula.
Pre-operative evaluation► Thorough ocular examination to exclude any ocular disease like abnormalities of lids, lacrimal sac, conjunctiva (including conjunctival infections), cornea, uveal inflammation, glaucoma, posterior segment inflammatory/ degenerative condition etc.
Systemic examination to exclude hypertension, cardiovascular disorder, cerebro-vascular disease, chronic obstructive air way disorder etc. If any disorder is present, it should be adequately controlled before surgery
► ENT and Dental checkup to exclude septic focus
Treatment of cataract► Medical treatment: No medical treatment is effective once the lens opacity has developed.
► Surgical Treatment:
Indication for surgery:
1. Cataract – when routine work becomes difficult due to reduced vision (attributable to cataract)
2. Subluxated or dislocated lens
3. Lens induced complications like phacolytic uveitis / glaucoma, phacoanaphylactic endophthalmitis, phacomorphic glaucoma.
► Surgical Treatment:Options
I. Intracapsular lens extraction (ICCE): Method of intracapsular cataract extraction (ICCE), now becoming obsolete, by which the entire lens including the capsule is removed by rupturing zonular ligaments.
II. Extracapsular Cataract Extraction (ECCE):
1. Conventional ECCE
2. ECCE by small incision cataract surgery (SICS)
Steps of ECCE• Anaesthesia
a. General Anaesthesia : In children, psychiatric patients, senile dementia
b. Local anaesthesia: Retrobulbar block, peribulbar block, along with or without facial block , topical anaesthesia
2. Cleaning of lids with 5% betadine solution and instillation of betadine solution in conjunctival sac
4. Superior Rectus suture in case of conventional ECCE and SICS
5. Conjunctival flap in case of SICS
6. Scleral tunnel incision or Corneo-scleral section or corneal or corneal tunnel incision
7. Anterior chamber entry
8. Injection of ocular viscosurgical device (OVD) in anterior chamber (HPMC or Sodium Hyaluronate)
9. Capsulotomy ( can opener or continuous curvilinear capsulorrhexis, CCC)
10. Hydrodissection and Hydrodelineation
11. Nucleus delivery (in conventional ECCE and SICS) / Phacoemulsification of nucleus (in phacoemulsification, machine , through titanium needle provides energy for emulsification of nucleus, needle vibrates at an speed of 20,000 Hz and pulverizes the nucleus)
12. Cortical clean up by aspiration and irrigation (BSS or Ringer lactate is used as irrigating fluid)
13. Filling of lens capsule (capsular bag) with OVD
14. Insertion of posterior chamber IOL (in the bag, in case of complications in the ciliary sulcus)
15. Removal of OVD from anterior chamber
16. Closure of wound of entry (corneoscleral wound requires sutures 10-0 silk or nylon), phaco and SICS incisions are self sealing.
Complications of Cataract Surgery• Due to local anesthesia: Retrobulbar haemorrhage, globe perforataion, oculocardiac reflex etc.
• Intra-operative complications : detachment of descemet’s membrane, damage to corneal endothelium, zonular dialysis, posterior capsular rupture
III. Early post-operative complications: wound leak and complications related to it (iris prolapse, flat anterior chamber), secondary glaucoma, postoperative infection, lens matter induced uveitis etc.
IV. Late post-operative complications: cystoid macular edema, posterior capsular opacification, corneal endothelial decompensation causing corneal edema, retinal detachment, displacement of IOL etc.