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Home / Ophthalmic Pathology / Sclera

Normal Sclera:

Mamalis Sclera 01      Mamalis Sclera 01 labeled

Transition from corneal limbus to sclera

Mamalis Sclera 02     Mamalis Sclera 02 labeled

  • White tissue that is continuous with the corneal limbus anteriorly and the optic nerve sheath dura posteriorly
  • The inner 1/3 of the posterior sclera continues as the lamina cribrosa through which axonal fibers pass into the optic nerve
  • Scleral tissue is derived from neural crest
  • Composed of episclera, stroma, and lamina fuscia
  • Thinnest justposterior to muscle insertions
  • Episclera is the thin fibrovascularcovering of the sclera
  • Composed of loosely arranged collagen fibers and a vascular plexus
  • Thinnest at limbus
Scleral Stroma
  • Composed of dense type I collagen
  • In general, collagen fibers run parallel to globe, but fibers have a random arrangement (this is why the sclera is opaque and the cornea is clear
  • Fibers are thicker and more variable in size and orientation than in the cornea
  • Transmural emissarial channels pass nerves and blood vessels through the globe wall
    • Posterior-transmit posterior ciliary arteries and nerves
    • Equatorial-transmits vertex veins
    • Anterior-for anteriorciliary arteries /veins/nerves
Lamina Fuscia
  • Bridging collagen fibers that bind uvea to sclera
  • Strongest attachments at emissary channels and ciliary body

Disorders of the Sclera:

Episcleral Osseous Choristoma:
  • Rarest ocular choristoma (choristoma = mature tissue elements in abnormal location)
  • Most commonly superotemporal single, stationary, hard, white plaque or nodule1Generally sporadic (not inherited)
  • Round, up to 1 cm
  • Contains mature lamellar bone
  • Isolated finding -Zeroother abnormalitiespresent
  • Nanophthalmos is when the eye is uniformlydecreasedsize of eye with normal lens
  • Differentiated from most forms of microphthalmoswhich represent eyes that have structural abnormalities such as persistent fetal vasculature, coloboma, etc.
  • Severe hyperopia–Axial length < 21 mm, White-to-White < 11 mm
  • Thickened choroid and sclera
  • Usually bilateral
  • Predisposed for
    • Uveal effusion
    • Angle closure glaucoma
    • Glaucoma due to elevated episcleral venous pressure
    • Perioperative complications with ocular surgery
    • May be sporadic or inherited (autosomal dominant or autosomal recessive)
Nick’s Tips: look for a small, hyperopic eye with otherwise normal structure and function.
Simple Episcleritis:
  • Slightly tender, red sector, movable
  • Blanches with phenylephrine (scleritis does not)
  • May possibly be associated with systemic illness, but frequently is not.3,4Consider systemic tests if recurrent or atypical.
  • May be associated with other ocular conditions in 50% of cases4
  • Lymphocytic perivascular infiltrate
  • Zero granulomatous inflammation
Nodular episcleritis:
  • Most often affects women with rheumatoid arthritis
  • Nodules are necrotic granulomatous inflammation
  • Palisading epithelioid histiocytes around core of necrotic collagen
  • Spontaneous resolution common-may use NSAID, predisolone
Nick’s Tips: Episcleritis is relatively common, usually benign, and frequently self-limited.
Mamalis Sclera 03     Mamalis Sclera 03 labeled
Low magnification view of scleritis
Mamalis Sclera 04     Mamalis Sclera 04 labeled
Higher magnification view of scleritis
  • Painful, often progressive
  • May have serious sequelae including loss of vision, loss of the eye, and death
  • Associated with autoimmune vasculitis diseases.3
    • Rheumatoid arthritis–most common (10 -33%) –usually anterior, diffuse scleritis. The presence of scleritis is rheumatoid arthritis is associated with more aggressive disease and greater mortality.
    • Wegener’s granulomatosis–2ndmost commonassociation with scleritis.3Granulomatous inflammation of the upper and lower respiratory tracts and small vessel vasculitis. Associated with cANCA. May have posterior or anterior scleritis.
    • Systemic lupus erythematosus –when associated withSLE, it indicates active diseaseoPolyarteritis Nodosa–vasculitis of medium-sized muscular arteries. 20% have eye findings including anterior and posterior scleritis, uveitis, keratitis, and optic neuritis.
    • Relapsing Polychondritis–small vessel vasculitis that most frequently affects cartilaginous structures (ear, nose, larynx, trachea)
    • Cogan Syndrome –inflammatory disease of the eye and audiovestibular system. May also be associated with interstitial keratitis, anterior or posterior scleritis.
    • Takayasu disease –chronic giant-cell vasculitis of large and medium sized arteries. Has a predilection for the aortic arch. Scleritis has been reported in several cases.3
    • Sarcoidosis
    • Porphyria
    • Infectious Causes
      • Syphilis
      • Tuberculosis
      • Lyme disease
      • Brucellosis
      • Herpes Zoster
  • May be anterior or posterior, or extend to other structures
  • Mimicked by
    • Primary ocular/CNS lymphoma
    • MALT lymphoma
Types of Scleritis:
1)  Anterior Scleritis: severe pain and photophobia, 50% bilateral, sectoral inflammation
2)  Posterior Scleritis: unilateral proptosis, retro bulbar pain, visual field loss pain with EOM. May cause optic neuritis.
3)  Necrotizing (nodular of diffuse) -palisading histiocytes around necrotic core. Lymphocytes peripheral to histiocytes. As it resolves, necrotic stroma resorbed leaving thinned scleral remnant. Severe ectasia predisposes to herniation of uveal “scleromalacia perforans” tissue.
4)  Non-necrotizing inflammation-zero granuloma, usually heals without thinning of sclera vasculitis may be present.

Degenerations of the sclera:

Scleral staphyloma:

Mamalis Sclera 05     Mamalis Sclera 05 labeled

Gross photograph of scleral staphyloma

Mamalis Sclera 06     Mamalis Sclera 06 labeled

Gross photograph of scleral staphyloma

Mamalis Sclera 07     Mamalis Sclera 07 labeled

CT of posterior scleral staphyloma

Mamalis Sclera 08     Mamalis Sclera 08 labeled

Low magnification view of scleral staphyloma, showing thinning of sclera



  • Ectasias of the sclera lined by uveal tissue
  • May occur at weak points in the sclera in children
  • May occur in congenital glaucomadue to long standing raising IOP
  • Variable patches of blue-grey pigment from uveal tissue showing through
  • May be associated with scleromalacia and scleritis

Neoplasms of Sclera:

  • Very rare
  • Usually originate from episclera or Tenon’s capsule
  • Fibrous histiocytoma: benign proliferation of spindle cells in mat-like (storiform) pattern5
Nodular Fasciitis:
  • Reactive process-firm, grey nodule at limbus or muscle insertion
  • Likely occurs in response to trauma6
  • Benign, and self-limited, but usually excise
  • Very rare
  • Spindle cells in whorl-like fashion with mitotic figures6
  • Notripolar (atypical) mitoticfigures
  • Looks similar to sarcoma


1. Bicer T, Soylemez H. Epibulbar osseous choristoma. Case Rep Ophthalmol Med 2014;2014.
2. Carricondo PC, Andrade T, Prasov L, Ayres BM, Moroi SE. Nanophthalmos: A review of the clinical spectrum and genetics. J Ophthalmol. 2018.
3. CE, Meier FM. Systemic disorders associated with episcleritis and scleritis. Current Opinion in Ophthalmol. 2001;12(6):471-478.
4. Akpek EK, Uy H, Christen W. Severity of episcleritis and systemic disease association. Ophthalmology 1999;106(4):729-731.
5. Su GW, Perez N, Simons K. Solitary fibrous tumor of the sclera. Arch Ophthalmol. 2007;125(11):1572-1574.
6. Massop DJ, Frederick PA, Li HJ, Lin A. Epibulbar Nodular Fasciitis. Case Rep Ophthalmol. 2016;7(1):262-267.