Ophthalmology for NEET-PG
Glaucoma for NEET-PG
Glaucoma is a group of optic neuropathies characterised by progressive retinal ganglion cell loss and visual field defects, usually associated with raised intraocular pressure. For NEET-PG, the key distinctions are open-angle versus angle-closure glaucoma, the features of an acute attack, the fundus and field findings, and the pharmacology of treatment. Primary open-angle glaucoma is the most common form, is painless and insidious, and produces gradual peripheral field loss with a raised cup-to-disc ratio, so it is often detected late. Primary angle-closure glaucoma is an emergency in which the drainage angle is suddenly blocked, causing severe eye pain, a red eye, a mid-dilated fixed pupil, corneal oedema with haloes around lights, and a hard eyeball, often precipitated by darkness or mydriatics in a hypermetropic eye with a shallow anterior chamber. Diagnosis uses tonometry to measure intraocular pressure, gonioscopy to assess the angle, fundoscopy for disc cupping, and perimetry for field defects, with an arcuate scotoma being characteristic. Medical treatment lowers intraocular pressure using prostaglandin analogues, beta blockers, alpha agonists, and carbonic anhydrase inhibitors, while acute angle closure needs urgent pressure reduction followed by laser peripheral iridotomy. Knowing the acute attack triad, the fixed mid-dilated pupil, disc cupping, and first-line prostaglandin therapy are recurrent exam anchors.
MedNext Academy | 3 min read
Glaucoma for NEET-PG
Glaucoma is a group of optic neuropathies characterised by progressive retinal ganglion cell loss and visual field defects, usually associated with raised intraocular pressure. For NEET-PG, the key distinctions are open-angle versus angle-closure glaucoma, the features of an acute attack, the fundus and field findings, and the pharmacology of treatment. Primary open-angle glaucoma is the most common form, is painless and insidious, and produces gradual peripheral field loss with a raised cup-to-disc ratio, so it is often detected late. Primary angle-closure glaucoma is an emergency in which the drainage angle is suddenly blocked, causing severe eye pain, a red eye, a mid-dilated fixed pupil, corneal oedema with haloes around lights, and a hard eyeball, often precipitated by darkness or mydriatics in a hypermetropic eye with a shallow anterior chamber. Diagnosis uses tonometry to measure intraocular pressure, gonioscopy to assess the angle, fundoscopy for disc cupping, and perimetry for field defects, with an arcuate scotoma being characteristic. Medical treatment lowers intraocular pressure using prostaglandin analogues, beta blockers, alpha agonists, and carbonic anhydrase inhibitors, while acute angle closure needs urgent pressure reduction followed by laser peripheral iridotomy. Knowing the acute attack triad, the fixed mid-dilated pupil, disc cupping, and first-line prostaglandin therapy are recurrent exam anchors.
Glaucoma is a group of optic neuropathies characterised by progressive retinal ganglion cell loss and visual field defects, usually associated with raised intraocular pressure. For NEET-PG, the key distinctions are open-angle versus angle-closure glaucoma, the features of an acute attack, the fundus and field findings, and the pharmacology of treatment. Primary open-angle glaucoma is the most common form, is painless and insidious, and produces gradual peripheral field loss with a raised cup-to-disc ratio, so it is often detected late. Primary angle-closure glaucoma is an emergency in which the drainage angle is suddenly blocked, causing severe eye pain, a red eye, a mid-dilated fixed pupil, corneal oedema with haloes around lights, and a hard eyeball, often precipitated by darkness or mydriatics in a hypermetropic eye with a shallow anterior chamber. Diagnosis uses tonometry to measure intraocular pressure, gonioscopy to assess the angle, fundoscopy for disc cupping, and perimetry for field defects, with an arcuate scotoma being characteristic. Medical treatment lowers intraocular pressure using prostaglandin analogues, beta blockers, alpha agonists, and carbonic anhydrase inhibitors, while acute angle closure needs urgent pressure reduction followed by laser peripheral iridotomy. Knowing the acute attack triad, the fixed mid-dilated pupil, disc cupping, and first-line prostaglandin therapy are recurrent exam anchors.
Key points
- **Definition:** Progressive optic neuropathy with retinal ganglion cell loss and characteristic visual field defects, usually linked to raised intraocular pressure.
- **Open-angle features:** Most common form, painless and insidious, with gradual peripheral field loss and increased cup-to-disc ratio, often detected late.
- **Angle-closure emergency:** Sudden severe eye pain, red eye, corneal oedema, haloes around lights, a hard eyeball, and vomiting mark an acute attack.
- **Fixed mid-dilated pupil:** A mid-dilated, fixed, non-reactive pupil is the classic sign of acute angle-closure glaucoma.
- **Predisposing anatomy:** Hypermetropic eyes with shallow anterior chambers and narrow angles are prone to angle closure, precipitated by dim light or mydriatics.
- **Disc cupping:** Fundoscopy shows increased cup-to-disc ratio, notching of the neuroretinal rim, and bayoneting of vessels in advanced disease.
- **Field defects:** Perimetry shows arcuate scotomas, nasal step, and eventually tunnel vision, with central vision preserved until late.
- **Diagnostic tools:** Tonometry measures pressure, gonioscopy assesses the drainage angle, and perimetry maps the field defects.
- **First-line drug:** Prostaglandin analogues such as latanoprost are first-line for open-angle glaucoma and increase uveoscleral outflow.
- **Acute treatment:** Acute angle closure needs urgent pressure lowering with intravenous acetazolamide and topical agents, then laser peripheral iridotomy.
- **Drug cautions:** Topical beta blockers can worsen asthma and heart block. Pilocarpine causes miosis and helps break an acute attack.
Frequently Asked Questions
How do open-angle and angle-closure glaucoma differ?
Open-angle glaucoma is painless and insidious with gradual field loss, while angle-closure is an acute emergency with severe pain, a red eye, and a fixed mid-dilated pupil.
What is the classic sign of acute angle-closure glaucoma?
A mid-dilated, fixed, non-reactive pupil, along with a hard painful red eye and haloes around lights, is the classic presentation.
Which drug is first-line for open-angle glaucoma?
Prostaglandin analogues such as latanoprost are first-line because they lower intraocular pressure by increasing uveoscleral outflow.
What field defect is characteristic of glaucoma?
An arcuate scotoma and nasal step are characteristic early defects, progressing to tunnel vision with preserved central vision until late.
How is acute angle-closure glaucoma treated?
It needs urgent intraocular pressure reduction with intravenous acetazolamide and topical agents, followed by definitive laser peripheral iridotomy.
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