Sclera/Episclera

Question 1

Describe the sclera?

Answer 1

• Outer tough shell of eye
• Protects delicate structures inside
• Anteriorly it becomes cornea (limbus)
• Posteriorly it forms optic nerve dural sheath
• It serves as a conduit for BVs & nerves
• It provides attachment points for EOMs
• Weakly attached to underlying Choroid
• Outermost layer is called Episclera
• Heals poorly due to poor blood supply
• “The white of the eye”

Question 2

What are the usual sclera measurements?

Answer 2

• Thickness ranges from 0.3mm to 1.0mm
• Thickest at optic nerve & thinnest behind insertion of muscles
  o Important as when eyeball perforates (bursts open) it usually does at thinnest part
• Sclera is white but can look blue in children because it is transparent
• Can also look yellow in jaundiced px

Question 3

Describe scleritis vs episcleritis?

Answer 3

• Scleritis is rare (0.08%), Episcleritis is not rare
• Anterior scleritis vs posterior scleritis
• Scleritis is inflammation of sclera – local isolated event or manifestation of systemic disease
• Systemic diseases such as Rheumatoid arthritis or Systemic Lupus Erythematosus
• 57% of px w/ scleritis have a disease association
• More common in women
• More prevalent in 4th-6th decade of life
• Trauma

Question 4

Describe scleritis?

Answer 4

• Pain, tearing or photophobia, ocular tenderness, & ↓VA
  o Pain is most common symptoms for which pxs seek medical assistance, & is best indicator of active inflammation
   Pain results from both direct stimulation & stretching of nerve endings by inflammation
• Severe, penetrating pain that radiates to forehead, brow, jaw or sinuses
• Awakens px during night
• Exacerbated by touch; extremely tender
• Only temporarily relieved by analgesics
• Often misdiagnosed w/ conjunctivitis – if px in severe pain then it is not conjunctivitis
• Redness DOES NOT blanch after topical applications of routine sympathomimetic dilating agents (Phenylephrine 10% eye drops) – if redness goes away after 10-15mins after 1 drop then it is NOT scleritis
• Need to perform full eye examination & refer for systemic work up
• Scleritis can cause severe keratitis, glaucoma, uveitis & formation of cataract
• Ultrasound or CT useful in posterior scleritis

Question 5

Describe anterior scleritis?

Answer 5

• Diffuse, nodular, necrotising (either w/ perforation or non-perforating)
• Red & painful eyes & vision can also be affected

Question 6

Describe posterior scleritis?

Answer 6

• Sclera becomes thickened – detected on ultrasound scan of globe
• Thickening of sclera causes choroidal folds
• Optic nerve can become swollen – vision would be significantly reduced

Question 7

What is the prognosis & treatment scleritis?

Answer 7

• Prognosis depends on underlying disease
• Chronic vs episodic
• Tx usually requires oral immunosuppression combined w/ aggressive topical steroids
• Oral non-steroidal anti-inflammatory drugs (NSAIDs) can also be useful (Ibuprofen)
• Surgery for perforation (v rare)
• Requires URGENT referral
• Usually needs review by Rheumatologists as well

Question 8

Describe episcleritis?

Answer 8

• Usually a mild, self-limiting, recurrent disease
• Most cases are idiopathic (unknown cause), although up to 1/3 have an underlying systemic condition (Rheumatoid arthritis & connective tissue disorders)
  o FBs can also cause episcleritis
• Diffuse vs nodular
• Nodular more prolonged & painful than diffuse
• Diffuse episcleritis (84% of cases) is more common than nodular scleritis (16% of cases)
• Mean age of all pxs w/ episcleritis is 47.4 years

Question 9

What is the episcleritis prognosis?

Answer 9

• Prognosis is good
• Self-limiting disease
• Injection in episcleritis blanches w/ installation of 10% phenylephrine ophthalmic drops but not in scleritis
• Episcleritis can cause uveitis & raised IOP - rare
• Diagnosis is clinical
• Good history taking is essential
• Full eye examination required
• Sometime requires blood tests if systemic association is suspected

Question 10

What is the treatment for episcleritis?

Answer 10

• Nothing
• Lubrication
• Topical steroid – in few cases
• Topical NSAID (e.g. acular)
• Systemic Steroid for more severe cases (rarely)
• Managed in community but can be referred if diagnosis is in doubt or if px is not responding to tx

Question 11

What are the important investigations for scleritis & episcleritis?

Answer 11

• Need to be able to tell difference between scleritis and episcleritis
• Scleritis:
  o Severe condition w/ significant co morbidity, reduction of vision
• Episcleritis:
  o Self-limiting disease, maybe w/ discomfort but usually successfully treated
• Keratitis, conjunctivitis, episcleritis, scleritis
• Blur vision? Pain (main symptom in scleritis)? Watery eye? Sticky? Exudation?
• SL features
• Fundoscopy
• History
• Systemic inquiry
• Scleritis is v bad – requires URGENT referral
• Episcleritis is okay – managed in community but can be referred if diagnosis is in doubt or if px is not responding to tx