AAO - MOC - 2014

1. Filamentary keratopathy
I. Describe the approach to establishing the diagnosis
A. Describe the etiology of this disease
1. Filaments are composed of degenerated epithelial cells and mucus in
variable proportions
2. Seen in various corneal conditions which have in common an
abnormality of the ocular surface and altered tear composition
B. List the pertinent elements of the history
1. Common symptoms include: foreign body sensation, ocular pain (may
be severe), photophobia, blepharospasm, increased blink frequency,
and epiphora
2. Symptoms tend to be most prominent with blinking and alleviated when
the eyes are closed
C. Describe pertinent clinical features
1. Filaments stain with fluorescein and rose bengal dyes, facilitating
identification
2. Filaments range in length from 0.5 to several millimeters, and are
relatively strongly attached to the cornea
3. Often a small, gray, subepithelial opacity will be present beneath the
site of corneal attachment
4. Any underlying epithelial defect will stain with fluorescein prominently
5. The location of the filaments may provide a clue as to the cause
a. Superior cornea
i. Associated with superior limbic keratoconjunctivitis,
ptosis, or other causes of prolonged lid closure
b. Interpalpebral distribution
i. Associated with keratoconjunctivitis sicca, pharmacologic
dry eye, or exposure keratopathy
ii. After cataract extraction, filaments may be found
superiorly
c. Graft-host junction
i. Filaments after cornea transplantation typically reside on
the graft or at the graft-host interface or at the base of the
suture on donor side
6. Evidence of a predisposing condition
a. Ptosis
b. Lid lag
c. Incomplete lid closure
d. Punctate epithelial erosions associated with dry eye syndrome
e. Epithelial irregularity or epithelial defect
II. Define the risk factors
A. Any condition associated with irregularity (including desiccation) of the ocular
surface
1. Dry eye syndrome
Cornea/External Disease 50 © 2013, AAO

2. a. Keratoconjunctivitis sicca
b. Medication-induced
c. Posterior blepharitis (tear film instability)
2. Exposure keratopathy
a. Cranial Nerve (CN) VII palsy
b. Altered mental status with decreased blink rates
3. Ocular trauma (including surgery)
a. Epithelial abrasion/erosion
b. Contact lens overwear
c. Cataract extraction
d. Penetrating keratoplasty
e. Glaucoma filtering surgery
4. Prolonged occlusion
a. Ptosis
b. Prolonged patching
5. Ophthalmic disorders
a. Superior limbic keratoconjunctivitis
b. Epithelial keratitis (e.g., herpes simplex virus (HSV) keratitis)
and epithelial erosions (e.g., toxicity)
III. List the differential diagnosis
A. Dendritic lesions, such as HSV dendritic epithelial keratitis
B. Loosened sutures
C. Corneal abrasion
D. Non-adherent mucus or foam
IV. Describe patient management in terms of treatment and follow-up
A. Describe medical therapy options
1. Mechanical removal of filaments
2. Bandage contact lens (for relief of discomfort; may increase number of
filaments
3. Management of dry eye syndrome
a. Preservative free artificial tears
b. Punctal occlusion
c. Topical cyclosporine
d. Autologous serum drops
4. Mucolytics
a. N-Acetylcysteine
5. Topical sodium chloride (e.g. Muro 128 drops and ointment)
B. Describe surgical therapy options
1. Repair of contributory lid malposition
2. Tarsorrhaphy if secondary to severe dry eye syndrome
3. Superior conjunctival resection or cauterization if secondary to superior
limbic keratoconjunctivitis
V. List the complications of treatment, their prevention and management
Cornea/External Disease 51 © 2013, AAO

3. A. Mechanical removal of filaments – epithelial defect with secondary infection
1. Prescribe topical antibiotics after filament removal
B. Mucolytic treatment – toxic keratopathy
1. Discontinue use
VI. Describe disease-related complications
A. Major symptoms are ocular surface irritation and pain, and decreased vision
B. Filaments are an indicator of ocular surface disease
1. Complications are not typically secondary to the filaments, but the
underlying disease process
VII. Describe appropriate patient instructions
A. Once underlying process is effectively treated, filaments will resolve
B. Removal of filaments/use of mucolytics may be successfully employed when
filaments present, but are not definitive treatments, as filaments will recur
C. Continue with aggressive topical lubrication (if not possible to eliminate
underlying process)
Additional Resources
1. AAO, Basic and Clinical Science Course. Section 8: External Disease
and Cornea, 2013-2014.
Cornea/External Disease 52 © 2013, AAO