SCLERA

sclera is the white fibrous outer protective coat of the eye

continuous with the cornea anteriorly and the dura of the optic nerve posteriorly

made of avascular collagen, biochemically similar to joint cartilage, thus rheumatoid conditions may affect sclera and episclera

episclera is a thin layer of vascularized tissue covering the sclera anteriorly

EPISCLERITIS

usually unilateral; simple or nodular

non-specific immune response to irritants

Etiology

mostly idiopathic

associated with rheumatoid arthritis (RA), gout, Sjögren's syndrome, SLE, herpes zoster, tuberculosis, syphilis or coccidioidomycosis in one third of cases

more frequent in women than men (3:1)

Symptoms and Signs (see Colour Atlas OP16)

localized, elevated, segmental hyperemia, pink/purple-coloured globe

pain, swelling, tenderness, photophobia, lacrimation

topical vasoconstrictor reduces redness

lasts for weeks, typically recurs

Management

generally self limited

chilled artificial tears

topical corticosteroids for 3-5 days if painful (prescribed and monitored by ophthalmologist)

SCLERITIS

unior bilateral; sectoral, diffuse, nodular or necrotizing

anterior scleritis: engorgement of vessels deep to conjunctiva

may cause scleral melt, corneal ulceration, secondary glaucoma

posterior scleritis: may cause exudative retinal detachment

usually with episcleral involvement

Etiology

over half are a manifestation of systemic disease

•autoimmune e.g. SLE, RA

•granulomatous e.g. TB, sarcoidosis, syphilis

•metabolic e.g. gout, thyrotoxicosis

•infectious e.g. S. aureus, S. pneumoniae, P. aeurginosa, HSV, herpes zoster

chemical or physical agents e.g. thermal, alkali or acid burns

idiopathic

Symptoms and Signs (see Colour Atlas OP17)

severe pain and tenderness, more severe than in episcleritis

pain is best indicator of disease progression

conjunctival injection/scleral engorgement

bluish-red hue (in contrast to brighter red of episcleritis)

•topical vasoconstrictors will decrease redness of episcleritis, facilitating examination of scleritis

+/– decrease in visual acuity

Management

topical steroids, not used in primary care (may thin sclera)

systemic NSAIDs or steroids

SCLEROMALACIA PERFORANS

associated with severe rheumatoid arthritis (rare)

thinning of the sclera may lead to uveal dehiscence and globe rupture with minor trauma

prognosis poor, avoid steroids

very gentle examination of eye (Schiotz tonometry contraindicated)

BLUE SCLERAE

rare, uveal pigment seen through thin sclera

associated with: collagen vascular diseases (CVD) (e.g. osteogenesis imperfecta, Ehlers-Danlos syndrome, Marfan's syndrome), prolonged use of corticosteroids

may occur in normal newborns

STAPHYLOMA

localized ballooning of thinned sclera – anteriorly, equatorially or posteriorly

seen in rheumatoid arthritis, high myopia, glaucoma, trauma