Complications 1+2 Flashcards
Name 5 effects of CL wear on the anterior seg (7 possible):
- hypoxia
- desiccation
- debris entrapment
- microbial attachment
- mechanical effects
- surface deposits
- solution sensitivities
major effect of hypoxia on the cornea:
-other significant effects?
hypoxia causes corneal EDEMA
-others: increased BACTERIAL ADHERENCE, debris accumulation (microcysts), increased acidity (lactate accumulation), decreased healing and corneal sensitivity
What molecule is needed by the cornea to PREVENT swelling?
-how much does it swell overnight w/ nml lid closure?
oxygen
2-4% (not enough to cause clouding/epi swelling)
13% O2 to maintain nml mitosis
8% to prevent decreased corneal sensitivity
Use of WHICH lens type (broad category) with WHICH solution does NOT result in increased bacterial binding over 1 year?
SiHy lenses with UNpreserved solution; OR CLEARCARE soln
-use of any other lens type w/ PRESERVED soln resulted in increased bacterial binding
Define: COR (Critical Oxygen Requirement)
minimum Dk/t level required to prevent measurable corneal changes - different for DW and EW
i.e., for NO additional corneal swelling; DW = 23, overnight = 87
Mertz study also says a minimum 10% oxygen is needed to prevent swelling
Most common reason why pts drop out of CL wear?
dry eye/desiccation
Which bacteria are most common in normal cases of microbial keratitis? How about in CL-induced MK?
nml - staphlococcus
CL-induced - pseudomonas
What does an infiltrate with feathery borders and satellite lesions most likely indicate regarding its origin?
Most COMMON type of this organism?
it’s probably FUNGAL - ABx won’t work.
Fusarium. Also, could be candida, aspergillus, cephalosporin
Which type of microbe will cause pain out of proportion to the corneal findings, pseudodendrites, and a late ring infiltrate (and may originate from a water source)?
Acanthamoeba
What type of reaction do solutions yield in solution sensitivity CL reactions?
Type 4 hypersensitivity - to thimerosal, polyquad, etc. Certain combos of Sihy lens and soln may result in this more frequently
CC: vision is blurry/cloudy AFTER LENS REMOVAL. Doctor finds temporary shift toward MINUS power - what condition is this?
- also: distorted Ks, poor acuity endpt
- Tx?
epithelial edema
Tx: D/C lens wear, switch to higher Dk
CC: “mild haze/haloes” - but none rly.
Sx: DESCEMET’S STRIAE, FOLDS, CENTRAL HAZE (>18%)
stromal edema
Difference between microcysts and vacuoles?
- what do they indicate?
- note: both start @ basal cells initially
Microcysts: contain CELLULAR DEBRIS. Viewable with REVERSED illum.
Vacuoles: FLUID-FILLED. Viewable with UNREVERSED illum.
-both will cause SPK once they reach the surface
-both are 2’ CHRONIC HYPOXIA
Tx: D/C lenses if >50 present, will go away w/i several weeks
What percent oxygen is required to:
- prevent changes in epithelial mitosis and lactate accumulation?
- prevent decreased corneal sensitivity?
13% (lactate)
8% (sensitivity)
Non-compliance rate vs manufacturer recommendations? Vs doctor recommendations?
manufacturer - 67%
doctor - 60%
2-week replacement: 82!!!
1-month: 53%
Most common grading of NEOVASCULARIZATION? What are the other gradings?
Tx?
Grade 1: 2.5 (or any ONE w/i 3mm of corneal apex)
If grade 4: refit to Sihy…WATCH ALL STAGES for GHOST vessels
Polymegethism: change in ___
Pleomorphism: change in ___
-both are caused by what?
-Tx?
mega: size
morph: shape
HYPOXIA to ENDOthelial cells
Tx: change to Sihy or GP
CC: severe spectacle blur and PAIN x2-3 hrs after lens removal, lens intolerance, central SPK/clouding
- what condition is this? Hint: it’s secondary to increased PLIABILITY (2’ to increased edema)
- Tx?
SLACH - SL-Associated Chronic Hypoxia
-aka OVERWEAR SYNDROME
-Tx: D/C lens wear, Rx ATs, prophylactic ABx if necessary, or bandage CL (low water)
name the changes to each layer of the tear film w/ SCL and GP lenses
-lipid, aqueous, mucoid
lipid: thin or NONE
aqueous: present on SCL, dries quickly on GP
mucoid: loose attachment over SCL, NONE on GP
Pt presents w/ nonspecific complaints of CL dryness. Doctor notes a HIGH water content lens being used, and INFERIOR CENTRAL ARCUATE** staining
-what’s the diagnosis?
soft lens dessication
What’s the condition similar in appearance/complaint to soft lens desiccation, in GP LENSES?
-Tx?
Peripheral 3+9 staining (peripheral corneal desiccation)
Tx: refit the GP lens
CC: dry, gritty, decreased WT, REDNESS. Signs: (+)INFILTRATE w/ epi defect and accommpanying neo, (+)bulbar injection, (+)3+9 staining -what's the diagnosis? -cause? -Tx?
VLK - vascularized limbal keratitis
- cause: CHRONIC hypoxia (eventual epi/stromal hypertrophy allowing effects)
- Tx: D/C lens, TOPICAL ABx, STEROID to prevent scarring (infiltrate)
CC: dry, gritty, decreased WT, REDNESS.
Signs: **peripheral corneal desiccation w/ adjacent conj elevation. Also, excavation @ 3+9 and poor lens mvmt.
-Tx?
Dellen
Tx: D/C and focus on hydration therapy (ATs), Rx ABx if necessary
Pt presents for CL eval. Notes reuse of lenses, poor care lately, mild/moderate irritation, redness, tearing (OR NONE).
Signs: small, single or multiple NON-STAINING infiltrates seen in anterior stroma w/ (+) conj injection.
-what’s the diagnosis?
-Tx?
Infiltrative Keratitis
- cause: INFLAMMATORY; something on corneal surface (endotoxin, preservative).
- Tx: modify lens habits
