Domain III 3: Instrumentation for Measurement and Observation + Domain V: Diagnostic Fitting Flashcards
hemorrhaging and vascular changes in the retina associated with diabetes.
Diabetic Retinopathy
a loss of central vision due to an age-related degeneration
Macular Degeneration
when the retina tears or loses contact with the choroid
Retinal Detachment
a hereditary disorder that affects mainly the rods
Retinitis Pigmentosa
A rigid lens showing apical pooling indicates a:
Steep fit
A rigid lens showing apical touch indicates a:
Flat fit
Under slit lamp evaluation with fluorescein, corneal areas that appear dark and do not hold stain during
blinks are most likely:
dry spots
Staining at the inferior portion of the cornea of a soft lens wearer is usually caused by:
improper lens removal
What color filter enhances the fluorescein pattern behind a rigid lens containing a UV blocker?
yellow
Which slit lamp illumination is performed with the microscope placed precisely along the angle of
reflected light from the eye?
specular reflection
Corneal Edema, Overwear Syndrome, Corneal Anesthesia
Complicaitons of Pmma
what lens reduces Corneal Edema, Corneal Warpage, Polymegethsim
Gas permeable
i) Crisper Vision
ii) More Durable than Soft Lenses
iii) Aftercare of lenses is easier
iv) No need to change lenses every year, lenses can be cleaned and polished
v) Patients are more loyal
vi) Stabilizes Myopia in teenagers and reduces “Myopic Creep”
Advantages of RGP
i) Health History
ii) Refraction
iii) Pre-fitting examination with Slit Lamp
iv) Keratometry
v) Lens Options (Spherical Lenses, Toric Lenses) (Rigid or Soft?)
procedure for RGP fitting
Fit “On K” or “Steeper than “K”
Diameters 8.5 -9.2
Edges should be well tapered to minimize edge sensation with the upper lid
Intrapalpebral
the chord diameter over which the base curve extends on the posterior surface of the contact lens.
Posterior Optical zone
If the POZ is kept constant and the CPC is made steeper, Apical Vault is (increased/ decreased)= therefore lens movement is decreased forming a tighter fit
increased
Any change in the base curve requires a new lens.
true
If the POZ is kept constant and the CPC is made flatter, Apical Vault is (increased/decreased) therefore lens movement is increased forming a looser fit.
decreased
If the CPC is kept constant and the POZ is made smaller, Apical Vault will be
(increased/decreased) and therefore increase lens movement.
decreased
If the CPC is kept constant and the POZ is made larger, Apical Vault will (increased/decreased)
and therefore decrease lens movement.
increase
As diameter increased, the POZ is usually (increased/decreased) accordingly
increased
As diameter is decreased, the POZ is usually decreased accordingly, as this occurs,
apical vault (increased/decreased) and loosens the fit of the contact lens.
decreases
Any change in thickness requires a new lens
true
As thickness (increased/decreased), surface tension will increase causing a tighter fit.
decreases
If peripheral curves are made …, this will decrease the size of the POZ, apical
vault will decrease which will loosen fit of the contact lens.
wider
Widening peripheral curves (can/can’t) be done by adjustment on the original lens.
can
Peripheral curves (can/can’t) be made smaller and will require a new lens.
Can’t
If the fitter wants a larger POZ, a new lens will have to be ordered.
true
Correction of a Low Riding Lens (Minus Lens)
Intrapalpebral Fit (Lens may be too flat)
steepen base curve
Correction of a Low Riding Lens (Minus Lens)
Upper Lid Attachment (Lens may be too steep)
Flatten base curve or increase lens diameter or combination of both
thickness (increases/decreases), this will loosen the fit of the lens.
Increases
