NBEO Contact Lenses & Fitting 2 — Questions and Answers
Question 1: Giant papillary conjunctivitis (GPC) is defined by papillae on the upper tarsal conjunctiva that are larger than:
- 0.1 mm
- 0.3 mm
- 0.5 mm
- 1.0 mm (Correct answer)
Correct answer: 1.0 mm
GPC is characterized by papillae larger than 1.0 mm on the upper tarsal conjunctiva, differentiating it from normal papillary response.
Question 2: Contact lens-induced acute red eye (CLARE) is most commonly associated with colonization by which category of organism?
- Gram-positive cocci
- Gram-negative bacteria (Correct answer)
- Fungi
- Acanthamoeba species
Correct answer: Gram-negative bacteria
CLARE is most commonly associated with Gram-negative bacterial colonization of extended wear contact lenses, with endotoxins triggering the inflammatory response.
Question 3: Which contact lens-related complication presents with deep stromal infiltrates, significant anterior chamber reaction, mucopurulent discharge, and severe pain, representing the most vision-threatening condition?
- Contact lens peripheral ulcer (CLPU)
- Microbial keratitis (Correct answer)
- Superior epithelial arcuate lesion (SEAL)
- Infiltrative keratitis
Correct answer: Microbial keratitis
Microbial keratitis presents with deep stromal infiltrates, severe pain, and discharge, and represents the most serious and vision-threatening contact lens-related complication.
Question 4: Superior epithelial arcuate lesions (SEAL) are primarily caused by which mechanism?
- Chronic hypoxia from low Dk/t materials
- Mechanical trauma from the edge of a soft contact lens (Correct answer)
- Toxic reaction to preservatives in multipurpose solutions
- Microbial colonization beneath the superior lens edge
Correct answer: Mechanical trauma from the edge of a soft contact lens
SEALs result from mechanical trauma where the upper eyelid forces the peripheral edge of a soft lens against the superior corneal epithelium, creating an arcuate split.
Question 5: Which exposure is considered the primary risk factor for Acanthamoeba keratitis in contact lens wearers?
- Use of multipurpose solutions without rubbing
- Exposure to tap water or swimming while wearing lenses (Correct answer)
- Hydrogen peroxide system non-compliance
- Sleeping in daily wear silicone hydrogel lenses
Correct answer: Exposure to tap water or swimming while wearing lenses
Water exposure (tap water, swimming, showering with lenses) introduces Acanthamoeba to the lens environment and is the primary modifiable risk factor for Acanthamoeba keratitis.
Question 6: Corneal neovascularization in contact lens wearers is primarily driven by which pathophysiologic mechanism?
- Mechanical irritation stimulating limbal cell proliferation
- Chronic hypoxia inducing VEGF release from the corneal epithelium (Correct answer)
- Toxic preservative accumulation causing limbal inflammation
- Allergic response to lens deposits activating mast cells
Correct answer: Chronic hypoxia inducing VEGF release from the corneal epithelium
Chronic corneal hypoxia triggers vascular endothelial growth factor (VEGF) release, stimulating new vessel ingrowth from the limbal vascular plexus into the avascular cornea.
Question 7: A contact lens patient presents with a small (<1 mm), round, white peripheral stromal infiltrate with overlying epithelial staining, minimal pain, and no anterior chamber reaction. The most likely diagnosis is:
- Microbial keratitis
- Acanthamoeba keratitis
- Contact lens peripheral ulcer (CLPU) (Correct answer)
- Thygeson superficial punctate keratopathy
Correct answer: Contact lens peripheral ulcer (CLPU)
CLPU presents as a small, round, peripheral stromal infiltrate with overlying epithelial staining in extended wear users, and is distinguished from microbial keratitis by its peripheral location, small size, and minimal pain.
NBEO Contact Lenses & Fitting 2
Giant papillary conjunctivitis (GPC) is defined by papillae on the upper tarsal conjunctiva that are larger than: