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33 Cards in this Set
- Front
- Back
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What are the five layers of the cornea?
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Epithelium, Bowman's layer, Stroma, Decemet's membrane, Endothelium
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Cornea
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The most refractive lens of the optical system of the eye, supplies 70% of total power. |
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Epithelium (layer 1)
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10% of total corneal thickness. Composed of cells that are basement level, which travel to the top and protect the eye when needed. |
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Bowman's Layer
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Condensed outer section of the stroma
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Stroma (3rd layer)
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Makes up 90% of the total corneal thickness
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Decemet's Membrane (fourth layer)
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Basement membrane secreted by the endothelium
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Uniqueness of cornea
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The cornea has to be transparent in order for light to pass through the eye and form an image. |
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Anisocoria
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Unequal pupil size
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Subjective
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Patients give you information, why they want to wear contacts, their motivation, it is the personal side of the exam from THEIR SIDE |
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Objective
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What you as the CL/Fitter can see and test |
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Types of test during objective evaluation
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Visual acuity, corneal measurements, slit lamp evaluation, contact lens analysis
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Assesment
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Subjective and objective findings analysis Documentation Information is reviewed with patient |
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Plan
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Reivew lens options, treatment options, cost wear schedule, solution follow up
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Keratometry: Index of refraction used to calibrate keratometer
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1.3375 |
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Keratometor Normal Range
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36D-52 D
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Extended Range (Upper Range)
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+1.25 lens, can extend range up to 61D
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Extended Range (Lower Range)
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-1.00 lens, can extend the range 30D
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Slit Lamp
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Microscope and lamp all in one! Used by CL Fitters for pre-fit evaluations
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Slit lamp, before you start
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Clean the instrument, should be aligned and focused
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Slit lamp
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Used to determine the fit of a contact lens, too loose, too tight
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Diffuse Illumination
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Covers the lids, the eyelashes, and the cornea ***Used to look at the fit of contacts*** |
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Direct Illumination
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Both the beam and the light are focused on the area that needs to be examined. **used to look at the fit of contacts** |
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Indirect Illumination
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The beam of light is pointed adjacent to the area that is being examined. ***Used mainly to look at neo-vascularization*** |
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Retro Illumination
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Used to backlight the area that is being studied. Light is reflected off the iris or off the crystalline lens.
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Sceloric Scatter
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Checks for corneal edema, bubbles under the lens, edge fit of soft lens, lens position and movement: Beam of light is directed toward the limbus, it transilluminates the cornea and produces a halo.
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Optic Section
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Narrowest beam, 1mm or less, allows you to see the pre-corneal tear film @ 45 degree angle. ***used to determine the tear lens under rigid contacts** |
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Five Criteria for Contact Lenses
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1. Corneal coverage 2. Lens Movement 3. Three Point Touch 4. Visual Acuity 5. Patient Comfort ***If it does not fit ALL five, it is not a good fit*** |
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Invented the corneal lens
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Tuhouy
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Kalt
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Shells for karataconous
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Anisocoria
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One pupil is larger than the other
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Pre-Corneal Team Film: What are the three layers, what do they do?
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1. Lipid Layer - Oily, protects the layer beneath it. 2. Aqueous - Watery substance, responsible for keeping the eyeball moist. 3. Mucin Layer: Function to make the cornea wettable by providing a surface over which the tears will spread with ease. |
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FDA Classifications, 4
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1. Low water, non-ionic 2. High Water, non-ionic 3. Low water, ionic 4. High water, ionic |
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High Water vs. Low Water Content
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More water: Makes lens material softer and more flexible. Helps to make it more comfortable. Harder for patients to handle. Higher water provides more oxygen permeability, but many also attract more deposits which reduces flow of O2.
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