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50 Cards in this Set
- Front
- Back
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Often combined with EDTA to enhance effectiveness, toxic with hydrogel lens, quaternary ammonium compound |
Benzalkonium Chloride (BAK) |
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Which preservative is BACTERICIDAL? |
Chlorhexidine |
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Which preservative is infective against yeast, fungi, and serratia? Has limited binding with GPs - not used with GPs, (used mostly for hydrogel lens) |
Chlorhexidine |
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Which preservative is mercury derivative, slow acting, with hypersensitivity to hydrogels? (good for GP's) |
Thimerosal |
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Which is NOT a true preservative? - used in combo to enhance bacterial action again pseudomonas |
EthylenediamineTetraacetate(EDTA) |
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Originally a solvent for CL materials, low molecular weight, bipolar, and water soluble with good antimicrobial activity --> bacteriostatic |
Benzyl Alchol |
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Low sensitivity with hydrogel lens, great antimicrobial activity especially with Serratia, possible toxic reaction in rigid lens solution |
Polyaminopropyl Biguanide (PAPB) |
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What are the two wetting agents? |
Polyvinil alcohol and methycellulose |
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Water soluble, relatively non-viscous, nontoxic to ocular surface, good spreading and wettability on the eye and lens surface *commonly used for soft CL solutions* |
Polyvinil alcohol |
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May retard regeneration of corneal epithelium - successful in more viscous GP's solution |
Methycellulose |
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Nonabrasive surfactants are mostly contained in __ cleaners, remove mucoproteins, lipids, debris, and ___ ___ is important for their effectiveness |
GP, digital pressure |
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Abrasive surfactants are ___ effective and mostly effective against mucoproteinaceous deposits |
more |
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What are 3 problems with abrasive surfactants? |
- Lens scratch - Induce minus lens power - Reduce CT |
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How can abrasive surfactant problems be eliminated? |
Using small-particle abrasive cleaner |
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What type of lens can be used if corneal astigmatism is >2.00D? |
- Back surface toric GP - Bi-toric GP - Aspheric GP |
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Back surface toric GP is used when the ____ is > than ____ astigmatism. What is the problem with back surface? |
Corneal>Refractive - Induced cylinder |
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Aspheric GP is mostly used for ___, however this causes ____ decentration |
ATR, lateral |
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Front surface toric GP lens are used when the ____ is > than ____ astigmatism. |
Refractive>Corneal - residual astigmatism
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Front surface toric GP tend to rotate between 5-15 degrees nasally OD and nasally OS because the inferior eyelid moves __ when you blink (not up and down) |
in |
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What are 4 histological changes seen with keratoconus? |
- Thinning of corneal stroma - Stretching of DM (Vogt's Striae) - Breaks in Bowman's zone - Iron deposit in corneal epithelium (Fleischer Ring) |
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- Monocular diplopia or “ghost” images - Patient may own several pairs of glasses - Frequent changes in Rx - Asthenopic complaints: photophobia, halos - Gradual decrease in VA - Often first clinical sign - “Scissors-like”motion in retinoscopy |
Early symptoms and clinical signs of keratoconus |
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Causedby long term CL wear with Hx. of hypoxia or mechanical effects (PMMA) - Reversible if CL’s are discontinued - No slit lamp sign of keratoconus - Keratoconus like scissors motion |
Corneal Warpage Syndrome |
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What results in flatten of superior cornea and steepening of inferior cornea? |
High riding RGP lens |
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Nipple cone is _-_mm, ___ in shape, and located infero-____ |
3-4mm, round, nasal |
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Oval cone is _-_mm, ___ in shape, and located infero-____ and infero-___ |
5-6, oval, nasal-temporal |
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Globus cone is >__mm and located infero-____ |
>6mm, temporal |
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- Can be corrected with spectacle - Sight increase in refractive astigmatism - Mild scissors reflex in ret - Slight or no keratometric mire distortion - Difficult to diagnose |
Stage 1 keratoconous |
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- Corneal distortion and irregular astigmatism - Increase in myopia and refractive astigmatism - VA 20/25-20/30+ spectacles will likely work - Simulated K’s ~48-50 (1-4D of keratometric steepning) |
Stage 2 Keratoconous |
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- Stimulated K's 50-55 - Decrease best corrected VA with spectacle - Difficult to get accurate “K” readings - Increase irregular astigmatism - SLE: Vogt’s striae, Fleischer's ring, corneal thinning |
Stage 3 |
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–Corneal steepening > 55D –Apical corneal scarring –Munson’ssign |
Stage 4 |
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When do you send a patient for a corneal transplant? |
When you have a corneal scar where VA can be improved with a RGP |
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Modified Bifocal Approach - Adding ___ power to the distance power of the non-dominant eye --> improve near acuity - Adding ___ power to the distance power of the dominant eye --> improve near acuity |
plus, minus |
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Enhanced Bifocal Approach - Fitting the dominant eye with a ___ lens and the non-dominant eye with ___ --> Will improve distance acuity - Fitting the non-dominant eye with a ___ lens for near, ___ the distance power of the bifocal on the dominant eye --> Will improve near acuity |
- single vision, bifocal
- single vision, decreasing |
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- Have distance Rx <+1.00and >0.75 astigmatism - Shows satisfaction with monovision, single vision contact lenses with reading glasses - Exhibits amblyopia or monocularity |
NOT good candidate for Proclear/Frequency 55/ Biofinity |
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What are 4 causes of Flexure? |
- Steep fit - Reduced CT - Large OZD - High flexibility (high Dk) |
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___ is caused by the bending force of the upper lid during blinking which induces toricity |
Flexure |
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How can you manage a flexure problem? (4) |
- Flatten BCR by 0.5mm - Increase CT by 0.02 per D of CA - Reduce OZD by 0.3mm - Change material from high to low Dk value |
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___ is permanently induced toxicity within the lens as a result of excessive digital pressure during cleaning |
Warpage |
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Inferior decentration is a result of a lens that is too ___ and ____. With ____ lens edge |
steep, heavy, inadequate - without lateral decentration |
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To minimize inferior decentration: - consider ___ BCR form myopic patient - keep CT to a minimum - use ___ designs - consider __ ____ fit |
- Flatter BCR - Lenticular - Lid attachment |
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Slight ____ decentration is beneficial for vision and comfort, Excessive decentration may result in lens adherence |
superior |
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To minimize superior decentration: - Consider ___ BCR - Use ___ edge designs - ____ CT |
- Steeper - thinner - increase |
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Lateral decentration is the most frustrating and may result from (2) |
- Decentered corneal apex - ATR astigmatism |
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Lateral decentration is managed by using ___ CL design (Boston envision) |
aspheric |
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To minimize lateral decentration: - Consider ___ BCR - fit larger ___ lenses - if options fail --> soft __ lens are indicated |
- steep - OAD - Soft toxic lens |
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Drying or dehydration of peripheral cornea - Occursin more than 50% of patients wearing GP - Insevere case corneal thinning occurs with ulceration, neo-vascularization and scarring - 3 and 9 o’clock staining |
Corneal Desiccation |
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What are 4 causes of corneal desiccation? |
- Poor wettable material - Poorly centered lenses - Excessive edge lift - Tear film stability |
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How do you manage a poor wettable material? (2) |
- Use low Dk materials, FS/A - Improve tear film |
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How do you manage a poorly centered lens? (2) |
- Lid attachment fit - Superior lens-to-conrea fitting relationship |
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How do you avoid excessively high edge lift? (3) |
- Use of tai-curve - Tetra-curve lenses - Use aspheric designs |
