Q1 LONG ANSWER 10M ★ High-yield

Describe the anatomy of the uveal tract. Classify uveitis and describe anterior uveitis with its management.

Ophthalmology · 3rd Professional

The uvea (uveal tract) is the middle, vascular, pigmented coat of the eye, comprising the iris, the ciliary body and the choroid.
The name is from the Latin uva, a grape, which the dissected coat resembles.

Part	Structure and function
Iris	A diaphragm with a central pupil, dividing the anterior from the posterior chamber. The collarette marks the junction of the pupillary and ciliary zones and is the thickest part; the crypts of FUCHS are gaps in the anterior border layer. Contains the sphincter pupillae (circular, parasympathetic via the third nerve and the ciliary ganglion) and the dilator pupillae (radial, sympathetic)
Ciliary body	Triangular, extending from the scleral spur to the ora serrata. The pars plicata bears 70 to 80 ciliary processes which secrete the aqueous and give attachment to the zonules; the pars plana is the flat posterior part, and the safe surgical entry site. The ciliary muscle has longitudinal (BRUCKE) fibres inserting into the scleral spur and trabecular meshwork — which is how pilocarpine opens the meshwork — and circular (MULLER) fibres, whose contraction relaxes the zonules and produces accommodation
Choroid	The most vascular tissue in the body, with the highest blood flow per unit weight of any tissue. Layers from without inward: HALLER’S layer (large vessels), sattler’S layer (medium), the choriocapillaris, and BRUCH’S membrane. It nourishes the outer retina including the photoreceptors and the whole of the fovea, and dissipates heat

Blood supply — and the division explains the clinical pattern of disease: the anterior uvea (iris and ciliary body) is supplied by the major arterial circle OF the iris, formed by the two long posterior ciliary arteries and the seven anterior ciliary arteries; while the posterior uvea (choroid) is supplied by the short posterior ciliary arteries. The two territories are largely separate.

The sun (Standardization of Uveitis Nomenclature) classification is anatomical, based on the primary site of inflammation:
Anterior uveitis — the primary site is the anterior chamber: iritis, iridocyclitis and anterior cyclitis. The commonest form by far
Intermediate uveitis — the primary site is the vitreous: pars planitis, posterior cyclitis, hyalitis

Grade	Anterior chamber cells (in a 1 × 1 mm slit beam)
0	Fewer than 1
0.5+	1 to 5
1+	6 to 15
2+	16 to 25
3+	26 to 50
4+	More than 50
Flare grading	0 none; 1+ faint; 2+ moderate with iris details still clear; 3+ marked with the iris hazy; 4+ intense, with fibrin or plasmoid aqueous

Feature	Non-granulomatous	Granulomatous
Onset	Acute and sudden	Insidious
Pain, redness and photophobia	Marked	Mild or absent — a relatively quiet eye
Keratic precipitates	Fine, small and white	Mutton-fat — large, greasy and yellowish
Iris nodules	Absent	Present — Koeppe and busacca
Course	Acute and self-limiting; recurrent	Chronic and persistent
Posterior segment	Usually spared	Frequently involved — choroiditis, vitritis
Typical causes	HLA-B27 disease, trauma, idiopathic, Behcet	Tuberculosis, sarcoidosis, syphilis, VKH, sympathetic ophthalmitis, toxoplasmosis, leprosy
Need for investigation	Usually none at a first mild attack	Always investigate

Symptoms — pain, dull and aching, worse at night; photophobia, which is marked and is caused by spasm of the inflamed iris on constriction; lacrimation; redness; and blurred vision. Note what is absent: there is NO discharge and NO itching, which distinguishes it from conjunctivitis at once
Signs — ciliary (circumcorneal) congestion, a violaceous ring that does not blanch with phenylephrine; keratic precipitates on the endothelium; cells and flare in the anterior chamber; miosis and a sluggish pupil, from irritation of the sphincter; iris nodules; posterior synechiae; hypopyon in severe cases; and an intraocular pressure that may be low (from ciliary shutdown) or high (from trabeculitis or clogging)
Posterior synechiae are adhesions between the iris and the anterior lens capsule, and are the reason cycloplegia is urgent. If they become complete through 360 degrees the result is seclusio pupillae, which prevents aqueous passing from the posterior to the anterior chamber; pressure then builds behind the iris, bowing it forward as iris bombe, which closes the angle and causes secondary angle-closure glaucoma. If a fibrous membrane covers the pupil the result is occlusio pupillae

Topical steroid — prednisolone acetate 1%, given intensively at first (hourly, or even every 15 minutes for the first few hours in severe cases) and then tapered slowly over weeks. Abrupt withdrawal causes rebound, and inadequate initial treatment causes synechiae — so the rule is hit it hard and withdraw slowly
Cycloplegic and mydriatic — homatropine 2% or atropine 1%, for the reasons above. Where synechiae are already forming, a subconjunctival "mydricaine" injection of atropine, adrenaline and procaine may break them
Treat the cause — and above all, exclude and treat infection before immunosuppressing: tuberculosis, syphilis, herpes and toxoplasmosis

All questions in Diseases of the Uveal Tract