LAB Flashcards
the clinical procedure used to measure only the anterior corneal radius of curvature and the amount and direction of the regular corneal astigmatism
KERATOMETRY
an objective examination for determining the nature of the corneal refracting surface and corneal stability in progressive myopia, keratoconus, after cataract extraction following the wearing of contact lenses/radial keratotomy and other corneal surgery
Keratometry
Keratometer is also known as
Ophthalmometer
What are the three essential elements of a keratometer?
Object of known size
A doubling mechanism
A magnifying device
What are the essential anatomic features that should be measured?
Horizontal Visible Iris Diameter
Palpebral Aperture Height
Pupil Size
Aids in determining the overall size of the lens and optic zone diameter
Horizontal Visible Iris Diameter
Measurement of limbus to limbus
HVID
Measurement from inner to outer canthus
Horizontal palpebral aperture
Meaurement between upper and lower lid margin
Vertical palpebral aperture
3 layers of pre-ocular tear film
Lipid, aqueous, mucoid layer
responsible for retarding the evaporation of the tears
Superficial oily or lipid
The bulk of the tear film
Aqueous/watery layer
serves as a wetting agent turning the hydrophobic cornea to a hydrophilic one
Inner mucoid layer
Functions of tear film
Provides regular refracting surface
transport oxygen to the cornea necessary for metabolism
washes away foreign bodies, and also provides nutrients to the eye.
This is the radius of the back central portion of the lens and is based in flat K reading
Base curve
