Biggest disadvantage of PMMA material is its lack of Right Ans - Gas
permeability
Layer that makes up 10% of the cornea Right Ans - Epithelium
Vertical measurement for palpebral fissure Right Ans - 15mm
Eyelid muscle responsible for lid closure Right Ans - Orbicularis oculi
A dense opacity of the cornea is called a: Right Ans - leukoma
Goblet cells that secrete that secrete mucous into tear film are located in
which structure Right Ans - Conjunctiva
Transition zone between the bulbar conjunctiva and the palpebral conjunctiva
is called Right Ans - fornix
Middle layer of the globe is mostly responsible for Right Ans - Nutrition
Pupillary constriction is called Right Ans - miosis
Bactericidal ingredient found in the precorneal tear film is Right Ans -
Lysozyme
The cornea is clear, and must remain clear, which means it must be ______, and
be free from ______. Right Ans - avascular, scarring
what are tarsal plates? Right Ans - two thin, elongated plates of dense
connective tissue, about 2.5cm in length. Contributes to it's form and support.
what is a prism ballast? Right Ans - prismatic shape used in contact lens to
stabilize the lens by preventing rotation
how does one achieve the rotational control of truncation? Right Ans - by
making the bottom edge of the lens flat
, what are principal meridians? Right Ans - the meridians of most and least
curvature, or greatest and least power on a cylindrical or toric surface
what is a bicurve lens? Right Ans - lens consisting of two posterior
curvatures; one central curve(base curve) and one peripheral curve
a soft lens should have a curve and diameter that will allow it to drape the
cornea, vault over the limbus, and extend how many mm into the sclera?
Right Ans - 1mm
what angle identifies the smallest angle? Right Ans - minimum visual angle
if the diameter is kept constant and the base curve is changed, the sagittal
depth of the lens changes. How steep is the base curve, how large is the sag,
and how steep is the fit? Right Ans - steeper the base curve, the larger the
sag and the steeper the fit
given the K's 42.00@180/42.50@90, a manifest Rx of -1.00-.50x180, and your
patient wanting to wear his lenses only on the weekends, which type of lens
would you suggest? Right Ans - soft spherical
describe the axial edge lift Right Ans - the vertical distance from the lens
edge to an extension of the base curve of a lens
what is apical bearing or apical touch Right Ans - posterior lens curvature
resting on the corneal apex
what is an interpalpebral fit? Right Ans - a well centered rigid lens that fits
between the upper and lower eyelids, where the upper lid does not control
the position of the lens.
in fitting a contact lens, if the fitter fits a lens on "K", what does that mean?
Right Ans - the lenses are fitted to parallel the flatter meridian of the cornea
What is fenestration? Right Ans - tiny hole in a contact lens, made to
enhance the transmission of tears and oxygen through the lens material
how to evaluate tear quality and quantity Right Ans - tear break up time; or
use Schirmers #1, or fluorescein, rose Bengal
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