Ophthalmology
Iris, Uveitis and Glaucoma
Iris and anterior chamber for MBBS and NEET-PG: anterior uveitis, HLA-B27, hyphaema and hypopyon, open-angle versus acute angle-closure glaucoma, mapped to NMC codes OP6.
MedNext Academy | 3 min read
Iris, Uveitis and Glaucoma
Iris and anterior chamber for MBBS and NEET-PG: anterior uveitis, HLA-B27, hyphaema and hypopyon, open-angle versus acute angle-closure glaucoma, mapped to NMC codes OP6.
This chapter covers the iris and anterior chamber, uniting the inflammatory diseases of the anterior uvea with the glaucomas that arise from problems of aqueous drainage. It teaches the recognition of anterior uveitis and its systemic associations, the distinction between the chronic open-angle and the emergency angle-closure glaucoma, and the role of gonioscopy and tonometry.
High-yield: Iris, Uveitis and Glaucoma
- Anterior uveitis (iridocyclitis) presents with a painful red eye, photophobia, blurred vision and a small, irregular pupil, with cells and flare in the anterior chamber.
- Keratic precipitates are inflammatory cells on the corneal endothelium; large greasy mutton-fat precipitates suggest granulomatous uveitis such as tuberculosis or sarcoidosis.
- Posterior synechiae are adhesions between the iris and lens that make the pupil irregular and can block aqueous flow.
- Cycloplegics such as atropine are given in anterior uveitis to relieve ciliary spasm and to prevent or break posterior synechiae.
- Uveitis with a positive HLA-B27 is linked to ankylosing spondylitis, reactive arthritis and inflammatory bowel disease.
- A hypopyon is a sterile or infective layer of white cells in the anterior chamber, while a hyphaema is blood in the anterior chamber, usually after blunt trauma.
- Primary open-angle glaucoma is a chronic, painless, bilateral optic neuropathy with a raised intraocular pressure, an open drainage angle and gradual peripheral field loss.
- Acute angle-closure glaucoma is a painful red eye with a hazy cornea, a fixed mid-dilated pupil, haloes around lights and nausea, and it is an emergency.
- The optic disc in glaucoma shows an increased cup-to-disc ratio, notching of the neuroretinal rim and, in advanced disease, bayonetting of vessels.
- Gonioscopy visualises the anterior chamber angle and is essential to classify glaucoma as open-angle or closed-angle.
- First-line medical treatment of open-angle glaucoma is usually a topical prostaglandin analogue, which increases uveoscleral outflow.
- Acute angle-closure is broken with intravenous acetazolamide, topical pilocarpine and hyperosmotic agents, followed by a peripheral laser iridotomy to prevent recurrence.
- Rubeosis iridis, new vessels on the iris, follows retinal ischaemia and can cause a difficult neovascular glaucoma.
- Tonometry measures intraocular pressure, with a normal range of about 10 to 21 mmHg, though normal-tension glaucoma occurs within this range.
Open-angle versus acute angle-closure glaucoma
- **Onset and pain:** Open-angle is chronic and painless; angle-closure is acute with severe pain, nausea and haloes.
- **Cornea and pupil:** Clear in open-angle; hazy cornea with a fixed mid-dilated pupil in angle-closure.
- **Field loss:** Gradual peripheral (arcuate) loss in open-angle; rapid visual loss in angle-closure.
- **Treatment:** Prostaglandin analogue first-line for open-angle; emergency pressure-lowering then laser iridotomy for angle-closure.
NMC competencies in this chapter
- **OP6.1:** Intraocular inflammation
- **OP6.2:** Acute and chronic iridocyclitis
- **OP6.3:** Systemic conditions presenting as iridocyclitis
- **OP6.4:** Hyphaema and hypopyon
- **OP6.5:** The anterior chamber angle
- **OP6.6:** Common anterior chamber conditions
- **OP6.7:** Glaucomas with shallow and deep anterior chambers
- **OP6.9:** Therapy for anterior chamber conditions
Frequently Asked Questions
What are the signs of anterior uveitis?
A painful red eye with photophobia, blurred vision and a small irregular pupil, with cells and flare in the anterior chamber, keratic precipitates on the cornea and sometimes posterior synechiae.
How does acute angle-closure glaucoma present?
As a sudden painful red eye with a hazy cornea, a fixed mid-dilated pupil, haloes around lights, markedly raised pressure and often nausea and vomiting. It is a sight-threatening emergency.
Why are cycloplegics used in uveitis?
They relax the ciliary muscle to relieve painful spasm and dilate the pupil to prevent or break posterior synechiae between the iris and lens.
What is the role of gonioscopy?
Gonioscopy lets the examiner view the anterior chamber angle to classify glaucoma as open-angle or closed-angle, which is essential because the two are managed differently.
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