# Cataract > Cataract for FMGE Ophthalmology: senile cortical, nuclear and posterior subcapsular types, phacoemulsification, IOL biometry, PCO and complications. - Canonical URL: https://prepelephant.com/topics/fmge/ophthalmology/cataract-fmge - Exam / course: FMGE · Subject: Ophthalmology - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Cataract", PrepElephant, https://prepelephant.com/topics/fmge/ophthalmology/cataract-fmge ## Direct answer Any opacity of the lens is a cataract, and painless, progressive blurring over months in an eye that is otherwise normal is its signature. Age-related cataract comes in three morphologies — cortical spoke opacities, nuclear sclerosis that browns the lens, and posterior subcapsular plaque that dazzles in bright light and blurs near work — and it remains the leading cause of blindness in India, responsible for roughly two-thirds of blindness in national surveys. Surgery is the only cure: phacoemulsification with foldable intraocular lens implantation through a 2 to 3 mm incision in urban practice, and manual small-incision extracapsular extraction at high-volume camps. Surgery is timed by the patient's visual needs, not by the cataract's ripeness. ## What you must remember - Posterior subcapsular cataract appears earliest and disables most, with glare in sunlight and poor near vision; causes include ageing, diabetes, steroid therapy and uveitis. - Nuclear sclerosis shifts refraction myotically — the "second sight" of reading again without glasses before vision finally fails. - Cortical cataracts cause monocular diplopia and spoke-like peripheral opacities seen against a red reflex. - Congenital cataract associates with rubella (with salt-and-pepper retinopathy, deafness and cardiac disease), metabolic disease and familial forms; unilateral cases are operated by about six weeks of age, bilateral by eight to ten weeks, to forestall deprivation amblyopia. - Optical biometry with keratometry and A-scan axial length feeds the SRK formula for intraocular lens power calculation — the Indian exam's favourite calculation method, with its A-constant. - Acute postoperative endophthalmitis presents on days two to five with pain, hypopyon and vitritis; late posterior capsule opacification, the commonest long-term complication, is opened with Nd:YAG laser capsulotomy. - Cystoid macular oedema (Irvine-Gass syndrome) explains unexplained vision loss weeks after uneventful surgery. - Sight-threatening suprachoroidal haemorrhage is the feared intraoperative catastrophe; spectacle correction remains the rule because a monofocal IOL has no accommodation. ## A routine case, worked end to end A 68-year-old farmer can no longer read bus numbers; the right eye records 6/36, the left 6/18, both improving to only 6/24 with pinhole. Slit-lamp examination shows brunescent nuclear sclerosis with cortical spokes; the fundus, once dilated, is healthy. Proceed stepwise as the system does. Document that glare and visual handicap justify surgery on the worse eye, and clear general fitness for a largely topical-anaesthesia day procedure. Biometry measures keratometry and axial length, and the SRK formula returns an IOL power around 22 dioptres for a posterior chamber lens. Phacoemulsification fragments the nucleus ultrasonically, cortical aspiration cleans the bag, and a foldable lens is injected into the capsular bag through the self-sealing incision. Review at one day, one week and six weeks: vision should reach 6/9 with a mild astigmatic correction. If instead this farmer returned on day four with severe pain and a hypopyon, the pathway changes to vitreous tap with intravitreal antibiotics or vitrectomy depending on vision. If he returned in a year complaining of gradual re-blurring with a hazy posterior capsule behind a well-centred IOL, a five-minute Nd:YAG capsulotomy restores the view. One operation, three possible timelines — that is how a cataract question is constructed. ## How the exam frames it The FMGE pattern splits into recognition, timing and complications. Recognition: match the morphology (cortical, nuclear, posterior subcapsular) to its symptom — glare, second sight or monocular diplopia. Timing: when to operate on congenital cataract, and why the answer is weeks, not years. Complications: rank posterior capsule opacification as the commonest late problem and endophthalmitis as the feared early one. Programme knowledge adds marks: cataract is the backbone of the National Programme for Control of Blindness and Visual Impairment, high-volume surgery camps and government-sponsored IOL implantation having driven India's falling blindness prevalence. ## Frequently asked questions ### Which cataract causes the earliest glare and near-vision difficulty? Posterior subcapsular cataract, because the opacity sits at the nodal point of the eye's optical axis and scatter is worst in bright light and miosis. ### How is intraocular lens power calculated before surgery? By keratometry for corneal power and A-scan or optical biometry for axial length, inserted into a formula such as SRK/SRK-T using the lens model's A-constant. ### What is the treatment of posterior capsule opacification? Nd:YAG laser posterior capsulotomy, a painless outpatient procedure that opens the opaque capsule behind the intraocular lens. ### When should unilateral congenital cataract be operated? Around six weeks of age, with bilateral cases by eight to ten weeks, followed by prompt aphakic correction and amblyopia therapy. ### Which organism and timing define acute post-cataract endophthalmitis? Typically coagulase-negative staphylococci or Staphylococcus aureus presenting two to five days after surgery with pain, hypopyon and vision loss. ### Why does a patient with nuclear cataract sometimes read without glasses again? Progressive nuclear sclerosis increases the lens's refractive power, producing a myopic shift called second sight — temporary, ending as the cataract matures.