unit 3 Flashcards
Myopic Lenses (concave)
(nearsighted-distance objects are blurry)
* -0.25 -> -20.00
and beyond!
Hyperopic Lenses (convex)
farsighted- near objects are blurry)
* +0.25 -> +14.00
and beyond
Astigmatic Lenses
(refractive error)
* -0.25 -> -6.00
and beyond!
- Lens clock
used to measure the base curve of the lens
-Black numbers are for convex
-Red numbers are concave
- Lens Aligning Pliers
Help you align any type of lens axis
- Pupilometer
Measure the pupil distance (PD)
-Distance – Infinity
-Near – 40cm
-When fitting progressive you ALWAYS want monocular measurement
- Penlight & Ruler
When measuring distant put penlight on top of the head
-When measuring near put penlight underneath chin
- Distometer & Power Wheel
Measure the vertex distance from the back surface of the spectacle lens to the cornea through a closed eyelid
Lensometer
Thin lines are sphere lines
Thick lines are cylinder lines
What types of lenses can we measure with a manual lensometer?
Single spherical lenses
Bifocal
Trifocal
Progressive
Contact lens
using lens clock
Measuring Base Curve
* Always at 180 and 90
* No tilting
* Middle tine doesn’t move
* Red is –
* Black is +
What is PD?
Measurement in mm from the optical axis of one pupil to the other pupil
-How would we duplicate a pair of eyeglasses?
-What measurements would we take?
-What tools will help us take them?
- Prescription
- Pupil Distance
- Optical centre
- Boxing system
- Vertex distance
- Base curve
- Lens thickness
- Pantoscopic tilt
- Frame wrap
nose adjusting pliers
indent on one side, flat on other side
helps move nose pads
round flat fliers
one side is round other side is nylon
used to tighten the frame on the temples or used to widen them. always use round part on inside of frame
