Exam 1- Gas Permeable Complications

Question 1

What are the 3 fitting goals of GPs?

Answer 1

Apical clearance, landing at 3 and 9 o’clock, unrestricted vertical movement

Question 2

Mechanical symptoms

Answer 2

Related to the lens design or fabrication

Question 3

Physiologic symptoms

Answer 3

Peripheral drying secondary to an unstable tear film

Question 4

T or F: 3 and 9 staining always disappears spontaneously and increases in severity

Answer 4

False, 3 and 9 staining RARELY disappears spontaneously more often increases in severity

Question 5

What are 4 ways of treating mechanical 3 and 9 staining?

Answer 5

Artificial tears, decrease overall diameter, blend peripheral edge lift, flatten peripheral edge lift

Question 6

What are some symptoms of vascularized limbal keratitis?

Answer 6

Moderate discomfort with some photophobia and lacrimation, lens awareness with decreased wearing time, visualization of defect by the patient

Question 7

What are some objective findings of vascularized limbal keratitis?

Answer 7

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

Question 8

How do you treat the early stages of vascularized limbal keratitis?

Answer 8

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

Question 9

What are signs of late stage VLK?

Answer 9

Significant patient symptoms of pain, increased conj injection, erosion of the elevated epithelial mass

Question 10

How do you treat the late stage VLK?

Answer 10

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

Question 11

Compare VLK and phylectenular keratoconjunctivitis.

Answer 11

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

Question 12

What is a dellen?

Answer 12

A local saucer-like depression in the peripheral cornea

Question 13

What is a dellen caused by?

Answer 13

Localized dryness, resulting in stromal dehydration, occasionally occurs in conjunction with 3 and 9 staining, may scar and become vascularized

Question 14

Are patients symptomatic with conjunctival xerosis or Bitot spot?

Answer 14

No, patients are asymptomatic with some minimal conjunctival injection towards the end of the day

Question 15

What is conjunctival xerosis or a Bitot spot?

Answer 15

Slightly elevated conj lesion, located intra-palpebral, keratinization of the conj epithelium

Question 16

Are patients symptomatic with GP lens adhesion?

Answer 16

No, patients are generally asymptomatic. Patients may notice lens adherence in the morning

Question 17

What are objective findings of GP lens adhesion?

Answer 17

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

Question 18

How often does GP lens adhesion occur?

Answer 18

25-80% of GP lens wearers in extended wear

Question 19

How does GP lens adhesion occur?

Answer 19

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

Question 20

What type of lenses cause lens adherence most often?

Answer 20

Large, flat and loose

Question 21

What is the cascade that leads to GP induced GPC?

Answer 21

Antigen on CL -> Immune response -> vascular changes -> basophils and mast cells accumulate -> release of ECF-A -> attracts eosinophils -> histamine release -> causes itch, erythema, edema

Question 22

What is a type of lipid specific GP Cleaner?

Answer 22

Optimum

Question 23

What is atomic force microscopy?

Answer 23

Assesses surface roughness at a nanoscoptic level

Question 24

What is a dimple veil?

Answer 24

Small circular indentations in the epithelium, correlates with the area of bubbles trapped beneath the lens, asymptomatic unless dense and over visual axis

Question 25

Myogenic ptosis

Answer 25

Dysgenesis of abnormal function of the levator muscle

Question 26

Aponeurogenic ptosis

Answer 26

Rupture of the tendon of the levator muscle/ disinsertion or thinning of the levator muscle aponeurosis

Question 27

What causes neurogenic ptosis?

Answer 27

Congenital Horner’s

Question 28

What causes myogenic ptosis?

Answer 28

Congenital, Myasthenia Gravis

Question 29

What causes aponeurogenic ptosis?

Answer 29

Surgery, GP wear, forced lid squeezing, rigid lens displacement of the tarsus, blind-induced lens rubbing, excessive force used in soft lens handling

Question 30

What are causes of non-aponeurogenic contact lens induced ptosis?

Answer 30

Edema, blepharospasm, papillary conjunctivitis

Question 31

What are 3 risk factors of contact lens induced ptosis?

Answer 31

High myopia, patient age, long term GP use