ABO Practical Exam with 100% correct answers

Cancelling effect- subtract prism amounts BU/BU BD/BD BI/BO Powers between 0.00 & +/- 3.00 Read in 1/8 diopters .12 .37 .62 .87 Lensometer is also referred to as Lensmeter, focimeter, vertometer To focus eyepiece 1) while turned off. Place white sheet of paper against lens stop. 2) turn focus ring all the way counter clockwise,and then back clockwise until sharp. 3) remove paper and turn lensometer on 4) move power drum to high plus, then turn away from you until sharp- should land at 0.00. To read HORIZONTAL prism Axis must be @ 180°, if not, transpose rx. P=hcmxd Prentice rule P(prism) Hcm(amount moved) D(diopter) BO/BO Compounds- add BI/BI Compounds- add BU/BD Compounds- add BU/BU Cancels- subtract BD/BD Cancels- subtract BI/BO Cancels- subtract Black numbers on lensometer power drum (+) Red numbers on lensometer power drum (-) When neutralizing, if you have a power that is in 1/8 diopters and need to subtract Add 1 to 1/8 amount Ex. .12, you would need to subtract .13 Focus sphere lines first, if cylinder lines focus first Rotate axis drum by 90° When you have cylinder power, turn the power drum to The high plus, then gradually reduce power until one of the meridians comes into focus. Where is the prism reference point (PRP) on progressives? centered directly between the two horizontal alignment engravings (or ink markings), usually about 2 to 4 mm below the fitting cross of the lens. Where is the distance reference point (DRP) located on progressive lenses? generally located approximately 4 mm above the Fitting Point, providing an area completely free of the progressive power gradient. Near reference point (NRP) represents the location on the surface that provides the full target Add power, which is the optimal location for verifying the Add power of the prescription. It is located at the center of the near checking circle ink marking. Major Reference Point: (MRP) The point on a lens where the patient is provided the prescription as written by the doctor. If prism is not called for in the prescription then the lens OC and the MRP are the same. Add power is The difference between the sphere and power in reading area of lens. *subtract full reading amount from sph. value Cylinder power is always used to determine if axis Meets ANSI standards Binocular PD Total PD of both eyes together. From one pupil to the other pupil. Monocular PD Individual PD of each eye. From pupil to bridge. Optical Infinity used to measure distance PD-is a distance of about twenty feet. Pupillometer set @ 40cm Used to measure near PD. About 16 inches Pupillomters set @ 65cm Used to measure intermediate PD. About 25.5 inches Take binocular PD for Bifocal Rx- measure for distance and near Critical Rx- which also includes intermediate Take monocular PD for Progressive lens- distance Single vision- near Single vision- distance Single vision- intermediate When should you use occluder? For noticeable eye abnormalities. Ex.: Strabismus. Also to check binocular PD by occluding each eye to see if eye moved when occluded. How to check for vertical imbalance 1) mark OD, OC by centering within retical 2) without moving the lens table, move to OS lens 3) if not still centered, there is imbalance. What type of Lens design has vertical imbalance as part of its design? Progressive lenses