Sclera and Episclera Flashcards
sclera is ____% of the outer fibrous layer fo the globe
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- sclera surrounds the globe
- extends from the ____ anteriorly to the ____ posteriorly
- merges with the _____
limbus;
optic nerve;
dural sheath of the optic nerve
3 layers of the sclera (outer to inner)
- episclera
- sclera
- lamina fusca
episclera:
- thin, outermost region of the sclera
- inner to ____
- merges with ____ and ____ 3 mm from the limbus
- composed of ____
- highly _____
Tenon’s capsule;
Tenon’s capsule; conjunctiva;
loose connective tissue (fibroblasts, collagenous fibers, ground substance);
vascularized (vessels are visible through the transparent conjunctiva
sclera:
- inner to ____
- composed of _____
- collagen type ____ is predominant
- arrangement of collagen contributes to strength and rigidity and white, opaque color
- elastin is abundant deeper in the sclera, especially near the rectus muscle insertions and more posteriorly
episclera;
thick, dense connective tissue (fibroblasts, collagenous fibers, elastic fibers, ground substance);
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lamina fusca:
- innermost aspect of the sclera
- adjacent to the ____
- modified ____
- contains large number of _____ that migrate from the choroid, giving it a _____
choroid;
scleral stroma;
melanocytes;
brown color
diameter of sclera for an emmetropic human adult eye:
- ____ horizontal
- ____ vertical
- ____ anteroposterior
~24.2 mm;
~23.7 mm;
~22.0-24.8 mm
sclera is thickest _____, decreases in thickness as it approaches _____, thinnest _____, increases in thickness _____, continues to increase in thickness toward the ____
posteriorly near the optic nerve; the equator of the globe; under the rectus muscles just before their insertion; at the muscle insertion site; limbus
blood supply of sclera:
- supplied by the ____
- vessels supplying the recuts muscles continue anteriorly as the _____
- form the _____ just anteriorly to the rectus muscle insertions
- capillaries are in the ____
- ____ is considered avascular (no capillaries)
- form a superficial and deep ____
- ____ is mobile
- ____ is non-mobile
- both are visible through the transparent conj
episcleral arterial circle; anterior ciliary arteries; episcleral arterial circle; episclera; sclera; episcleral plexus; superficial episcleral plexus; deep episcleral plexus
- sclera provides a strong, tough external framework to ____
- it maintains ____ by offering resistance to ____
- insertion site for ____
protect the delicate intraocular structures;
the shape of the globe;
internal and external forces;
EOMs
____ in the sclera allow nerves and blood vessels to enter and exit the globe
apertures and foramen
simple episcleritis
inflammation of the episclera involving the superficial episcleral plexus
nodular episcleritis
inflammation of the episclera involving the superficial episcleral plexus with an associated nodule
episcleritis etiology/associations
- idiopathic in 60% of cases
- collagen vascular disease and vasculitis; most common diseases include RA, SLE, GPA, PAN, Behcet’s
- systemic infection; most common infections include herpes simplex, herpes zoster, lyme, syphilis, TB
- others (topiramte, rosacea, atopy, gout, sarcoid, IBD, reactive arthritis, ankylosing spondylitis, psoriatic arthritis)
episcleritis demographics
- typically occurs between the ages of 20-40 years
- women > men
episcleritis laterality
unilateral or bilateral
episcleritis symptoms
- red eye(s)
- mild eye pain
episcleritis signs
- sectoral episcleral injection; can be diffuse (less common); episcleral vessels are large, course in radial direction, can be moved with a cotton swab and blanch with phenyl
- some secondary involvement of overlying conj vessels
- chemosis (edema) in the area of injection
- mobile nodule in nodular episcleritis
- rarely, AC rxn (cells/flare) may be present
episcleritis management
- self-limiting within days to weeks; cold compresses and topical lubricants for palliative therapy; mild topical steroid; oral NSAIDs as an alternative to topical steroids (some prefer)- ibuprofen or naproxen
- if infectious etiology, treat with appropriate anti-infective
- if bilateral, recurrent, or nodular and etiology is unknown, order lab work based on the most likely etiologies; initial episodes of unilateral simple episcleritis without systemic symptoms do not require lab testing
- if systemic etiology, refer out for systemic treatment
episcleritis pearls
- simple episcleritis ____% of cases vs nodular ____%
- simple episcleritis typically lasts ____ while nodular episcleritis can last ____
- nodular episcleritis is more likely associated with ____
- ____ can aid in differentiating between episcleritis and scleritis; instill and reexamine after 10-15 mins; vessels blanch in ____ but not in ____
80; 20 a few days; for weeks; systemic disease; phenylephrine; episcleritis; scleritis
diffuse anterior scleritis
inflammation of the anterior sclera involving the deep episcleral plexus
nodular anterior scleritis
inflammation of the anterior sclera involving the deep episcleral plexus with an associated nodule
anterior scleritis etiology/associatons
- idiopathic in 40% of cases
- collagen vascular disease and vasculitis (50% of cases); most common diseases include RA, SLE, GPA, PAN
- systemic infection; most common infections include herpes simplex, herpes zoster, lyme, syphilis, TB
- others (e.g., gout, sarcoid, IBD, reactive arthritis, ankylosing spondylitis, psoriatic arthritis)
anterior scleritis demographics
- typically occurs between the ages of 40-60 years
- women > men
anterior scleritis laterality
unilateral or bilateral
anterior scleritis symptoms
- red eye(s)
- severe, deep, boring eye pain; awakens at night; may radiate to adjacent facial regions (forehead, brow, jaw, or sinuses); worsens during eye movement; may have tearing
