STEPTRACKERSPECIAL SENSES | PATHOLOGY + PHYSIOLOGY + PHARMACOLOGY | HIGH-YIELD REVIEW

Uvea, Lens & Glaucoma

Inflammation of the uvea and its systemic links, why lenses cloud, and how aqueous outflow failure damages the optic nerve.

FOCUS ON
Anterior uveitis: painful red eye, photophobia, small pupil, cells in the anterior chamber — HLA-B27, sarcoid, JIA. Posterior uveitis: floaters, ↓ vision — toxoplasmosis, CMV. Open-angle glaucoma: silent, peripheral vision lost first, cupped disc. Closed-angle: sudden painful red eye, halos, fixed mid-dilated pupil, rock-hard eye — emergency; no atropine.
DISORDER
MECHANISM · CAUSE
FEATURES
CLUE · TREATMENT
Anterior uveitis (iritis)
Inflammation of iris/ciliary body: HLA-B27 diseases, sarcoidosis, JIA, Behçet, herpes
Pain, photophobia, ciliary flush, miosis, anterior chamber cells and flare, hypopyon
Topical steroids + cycloplegics
Posterior uveitis / chorioretinitis
Toxoplasma (most common infectious), CMV (AIDS, CD4 < 50), sarcoid, TB, syphilis
Painless floaters, ↓ vision; retinal lesions with vitreous haze
Toxo: "headlight in the fog" · CMV: "pizza pie" hemorrhagic retinitis
Uveitis in JIA
Oligoarticular, ANA ⁺ girls
Often painless and silent until vision lost
Routine slit-lamp screening
Cataract — age-related
most common cause of blindness worldwide
Lens protein oxidation and aggregation; UV, smoking
Painless gradual blur, glare from lights, faded colors; lost red reflex
Lens replacement surgery
Cataract — secondary
Sorbitol (diabetes), galactitol (galactosemia), glucocorticoids, radiation, trauma, Wilson (sunflower), myotonic dystrophy, hypocalcemia
Earlier onset; often posterior subcapsular (steroids, diabetes)
Infant cataract → galactosemia, congenital rubella
Ectopia lentis
Weak zonules
Marfan: lens up and out · homocystinuria: down and in
Fibrillin vs cystathionine synthase
Primary open-angle glaucoma
most common glaucoma
↓ outflow through trabecular meshwork → ↑ IOP (sometimes normal) → retinal ganglion cell loss
Painless; peripheral vision lost first; ↑ cup-to-disc ratio
Age, Black ancestry, family history, myopia, diabetes
Acute angle-closure glaucoma
Iris pushed forward (pupillary block) closes the angle; hyperopia, Asian ancestry; triggered by dilation (dark room, anticholinergics, sympathomimetics)
Sudden severe eye pain, headache, nausea, halos, ↓ vision; red eye, cloudy cornea, fixed mid-dilated pupil, hard globe
Emergency: IOP-lowering drops, acetazolamide, IV mannitol → laser iridotomy
Secondary glaucoma
Neovascular (diabetes, CRVO), steroid-induced, uveitis, pigment dispersion
Raised IOP from a known cause
Treat the cause
Congenital glaucoma
Abnormal angle development; Sturge-Weber, congenital rubella
Large cloudy cornea (buphthalmos), tearing, photophobia in an infant
Surgery

Mechanism — aqueous humor flow

Ciliary body epitheliumMakes aqueous (β, α₂, carbonic anhydrase)
→
Posterior chamber
→
Pupil
→
Anterior chamber
→
Trabecular meshwork → canal of Schlemm(+ uveoscleral outflow)

Open angle: meshwork resists outflow. Closed angle: iris physically blocks it — pupil dilation makes it worse, which is why mydriatics and atropine are dangerous.

Glaucoma drugs

DRUG
ACTION
SIDE EFFECT
Latanoprost (PGF₂α)
↑ uveoscleral outflow
Darker iris, longer lashes
Timolol (β-blocker)
↓ aqueous production
Bronchospasm, bradycardia
Brimonidine (α₂ agonist)
↓ production, ↑ outflow
Allergic conjunctivitis
Acetazolamide, dorzolamide
Carbonic anhydrase inhibition → ↓ production
Systemic: acidosis, paresthesias
Pilocarpine (muscarinic)
Miosis opens meshwork → ↑ outflow
Brow ache, dim vision
Mannitol
Osmotic dehydration of vitreous
Volume shifts

How it's tested

COMMON CONFUSIONAnterior uveitis makes the pupil small (iris spasm); acute angle closure makes it fixed and mid-dilated. Both cause a painful red eye.
THE TRAPA patient given an anticholinergic, or who sits in a dark cinema, then develops eye pain, halos and vomiting has angle closure — not migraine or gastroenteritis.
YOUR APPROACHPainful or painless → pupil (small, mid-dilated, normal) → IOP → systemic association (B27, sarcoid, diabetes, AIDS) → drug mechanism.

If you see… think…

Ankylosing spondylitis with painful red eye and small pupil → anterior uveitis
AIDS, CD4 30, floaters and hemorrhagic retinitis → CMV retinitis
Focal retinochoroiditis with dense vitritis → toxoplasmosis
Infant with cataracts, jaundice and E coli sepsis → galactosemia
Cataracts after years of inhaled/oral steroids → posterior subcapsular cataract
Lens dislocated upward and outward → Marfan syndrome
Painless gradual loss of peripheral vision, cupped discs → open-angle glaucoma
Sudden painful red eye, halos, vomiting, fixed mid-dilated pupil → acute angle-closure glaucoma
Glaucoma drop that darkens the iris → latanoprost
Drug to avoid in angle closure → atropine / any mydriatic