What are the three most important parameters of an RGP lens?

1. Diameter
2. Base Curve
3. Power

The radius of curvature of the cornea

The keratometer does not measure?

1. Contact Lens Fitting
2. Corneal cylinder can be used to determine the spectacle RX.
3. To help determine if the patient has kerataconus
4. Distorted mires could indicate pathology

1. Pre and post refractive surgery measurements
2. More accurate than keratometer for fitting RGP's
3. Helps when fitting keratoconics with RGP's
4. Easier to assess cornea with irregular astigmatism due to disease or trauma

1. Biomicroscope
2. Phoropter
3. Keratometer

1. Keeps the eye moist and lubricated
2. Traps debris and washes it away
3. Primary sourceof O2
4. Smooth refractive surface
5. Contains antibacterial substances-lysosomes
6. Helps to maintain corneal hydration

1. Lipid- Meibomian Glands
2. Aqueous - Main lacrimal gland and accessory lacrimal galnds Krause & Wolfring
3. Mucin - Goblet Cells

1. Epithelium
2. Bowman's layer
3. Stroma - lamellae
4. Descemet's membrane
5. Endothelium

1. Squamous cells
2. Wing cells
3. Basal layer of columnar cells

1. Refraction of light
2. Transmissions of light

1. Diffusion from aqueous humor
2. Conjunctival and episcleral capillaries located in limbus
3. Atmospheric O2 diffused through the tear film

1. Dissecting microscope
2. Illumination system

1. Observation of normal ocular sturctures
2. Observation of abnormal ocular structures
3. Contact lens fitting

1. Direct
2. Diffused
3. Indirect
4. Retro
5. Sclerotic Scatter

1. Parallelpiped
2. Optic section
3. Specular reflection
4. Conical beam

Total diameter and/or Optic zone

When using a Radiuscope to determine an accurate base curve radius of an RGP contact lens, it is important that the concave surface of the lens is what?

You would use a lensometer to measure which RGP parameter?

1. Reasons for CL wear
2. Medical History
3. CL history

Many types of medications can cause dry eye

1. Corneal Topography
2. Refraction

1. Externals
2. Conjunctiva
3. Cornea

1. Corneal diameter
2. Pupil diameter
3. Palpebral aperture height

Contact lens must be touching

1. Upper Sclera
2. Cornea
3. Lower Sclera

1. Adequate movement
2. Stable Vision
3. Good Centration
4. Undistorted Keratometer mires

1. Spin Casting
2. Lathe Cutting
3. Cast Molding

A contact lens can get lost behind the eye

True or False

Only patients between the ages of 18 and 35 can effectively wear contact lenses.

True or False

Contact Lenses are considered Medical devices

True or False

1. Soft
2. Rigid

1. Hard (PMMA)
2. RGP (CAB)

PMMA allows little to no oxygen to reach the cornea

True or False

RGP's are more comforatble to wear than soft lenses

True or False

Soft lenses are hydrophobic

True or False

Soft lenses have a larger diameter than RGP's

True or False

Hypoxia causes corneal edema

True or False

1. Lens thickness
2. Lens material

The Dk value of a soft lens is dependant on the water content of the lens

True or False

The thicker the CL, the greater the oxygen transmissibility

True or False

Low water content soft lenses have greater resistance to deposits

True or false

True

Non-ionic soft lens materials easily attract lens deposits

True or False

The spin casting method limits the ability to control the base curve

True or False

Lathe cutting can only produce RGP's

True or False

Cast molding is simple and reproducible

True or False

1. Eliminates fitting visit
2. "Used" diagnostic lens is avoided
3. The lenses manufactured at a lab may be just as effective as the best fitting diagnostic lens

1. Fewer re-orders (an optimum lens-to-cornea relationship has already been achieved)
2. Practitioner confidence in the fit
3. Patient has a chance to experience how an RGP will feel on the first visit
4. Ability to evaluate patient's vision on first visit

1. Convenience to patient (Patients receive replacement lens without delay)
2. You can fit directly from stock
3. Lens parameter changes can be made without delay

1. Burton Lamp
2. Biomicroscope

Why not fit a spherical RGP on a high astigmat?

Increased 3 and 9 o'clock injection, poor lens positioning, visual complaints, corneal curvature changes, failure to correct residual astigmatism.

1. With the Rule
2. Against the Rule
3. Irregular
4. Internal
5. Residual
6. Refractive
7. Oblique

1. Keratoconus
2. Trauma
3. Lasik

1. The toricity of the back surface of the cornea
2. The tilt of the crystalline lens with respect to the optic axis of the cornea

1. Front surface Toric
2. Back surface toric
3. Bitoric

1. Edge and Surface Polishing
2. Repowering
3. Peripheral curve blending or flattening

1. Box modification unit
2. Suction cup
3. Sponge tools
4. Radius tools

What type of polish can NOT be used and why?

1. Daily wear/ flexible
2. Extended Wear
3. Planned Replacement/Disposable
4. Tints
5. Torics
6. Bifocals

1. Visibility
2. Enhancing
3. Opaque

1. Irregular corneas ( keratoconus,ocular trauma)
2. Radial keratotomy
3. Chronic allergies
4. Chronic antihistamine use
5. Giant Papillary Conjunctivitis  (GPC)