Exam 1- Gas Permeable Complications Flashcards
What are the 3 fitting goals of GPs?
Apical clearance, landing at 3 and 9 o’clock, unrestricted vertical movement
Mechanical symptoms
Related to the lens design or fabrication
Physiologic symptoms
Peripheral drying secondary to an unstable tear film
T or F: 3 and 9 staining always disappears spontaneously and increases in severity
False, 3 and 9 staining RARELY disappears spontaneously more often increases in severity
What are 4 ways of treating mechanical 3 and 9 staining?
Artificial tears, decrease overall diameter, blend peripheral edge lift, flatten peripheral edge lift
What are some symptoms of vascularized limbal keratitis?
Moderate discomfort with some photophobia and lacrimation, lens awareness with decreased wearing time, visualization of defect by the patient
What are some objective findings of vascularized limbal keratitis?
Elevated epithelial lesion bridging the limbus, histologically found to have stromal involvement, diffuse ill-defined border, semi-opaque, conjunctival injection, edema and staining, corneal vascularization
How do you treat the early stages of vascularized limbal keratitis?
Reduce wearing time or discontinue wear, begin lubricating drops, redesign the lens (reduce lens diameter, flatten base curve, flatten peripheral curves), follow closely for recurrence
What are signs of late stage VLK?
Significant patient symptoms of pain, increased conj injection, erosion of the elevated epithelial mass
How do you treat the late stage VLK?
Discontinue lens wear for 1-3 weeks, combination antibiotic/steriod (i.e. Tobradex), redesign lens, consider piggyback (scleral under GP) if unable to discontinue GP wear
Compare VLK and phylectenular keratoconjunctivitis.
PK similar in appearance to VLK, VLK is mechanical, VLK heals quickly in 3-5 days, phlyctenulosis has a staph hypersensitivity, phlyctenulosis heals in 10-14 days
What is a dellen?
A local saucer-like depression in the peripheral cornea
What is a dellen caused by?
Localized dryness, resulting in stromal dehydration, occasionally occurs in conjunction with 3 and 9 staining, may scar and become vascularized
Are patients symptomatic with conjunctival xerosis or Bitot spot?
No, patients are asymptomatic with some minimal conjunctival injection towards the end of the day
What is conjunctival xerosis or a Bitot spot?
Slightly elevated conj lesion, located intra-palpebral, keratinization of the conj epithelium
Are patients symptomatic with GP lens adhesion?
No, patients are generally asymptomatic. Patients may notice lens adherence in the morning
What are objective findings of GP lens adhesion?
Localized ring-like corneal distortion (rarely stains with fluorescein), adhesion usually located in the periphery with one edge crossing the limbus, retention of debris and mucus beneath the stationay lens, mild punctate staining, fern-like pattern upon manipulation
How often does GP lens adhesion occur?
25-80% of GP lens wearers in extended wear
How does GP lens adhesion occur?
Created by a thinning of the post-lens tear film during sleep which creates a thin highly viscous mucus-rich tear (glue) between the lens cornea. Upon eye opening the force of the eyelid may be insufficient to initiate lens movement, the lens remains bound until the mucus film is diluted and thickened by the aqueous tears
What type of lenses cause lens adherence most often?
Large, flat and loose
What is the cascade that leads to GP induced GPC?
Antigen on CL -> Immune response -> vascular changes -> basophils and mast cells accumulate -> release of ECF-A -> attracts eosinophils -> histamine release -> causes itch, erythema, edema
What is a type of lipid specific GP Cleaner?
Optimum
What is atomic force microscopy?
Assesses surface roughness at a nanoscoptic level
What is a dimple veil?
Small circular indentations in the epithelium, correlates with the area of bubbles trapped beneath the lens, asymptomatic unless dense and over visual axis
Myogenic ptosis
Dysgenesis of abnormal function of the levator muscle
Aponeurogenic ptosis
Rupture of the tendon of the levator muscle/ disinsertion or thinning of the levator muscle aponeurosis
What causes neurogenic ptosis?
Congenital Horner’s
What causes myogenic ptosis?
Congenital, Myasthenia Gravis
What causes aponeurogenic ptosis?
Surgery, GP wear, forced lid squeezing, rigid lens displacement of the tarsus, blind-induced lens rubbing, excessive force used in soft lens handling
What are causes of non-aponeurogenic contact lens induced ptosis?
Edema, blepharospasm, papillary conjunctivitis
What are 3 risk factors of contact lens induced ptosis?
High myopia, patient age, long term GP use
