OpenOptix ABO Study Guide - Laramy-K Optical

two surfaces of Owen Aves’ lens created a progression in power; however the design had
one major flaw: it was difficult to include any cylinder power in the lenses so ultimately
the design was never produced commercially. The first commercially available PAL was
designed by Duke Elder in 1922 named the “Ultrifo”. This design utilized aspheric
surfaces to create a progression in power. The next commercially available PAL was a
lens called the Varifocal. Created by Offcine Galileo di Milano out of Italy in the 1950’s,
the design was inspired by Aves’ design. Milano’s design is referred to as an “elephant
trunk” design and utilizes only the front surface to create the progression in power. It
wasn’t until 1959 that the first modern day progressive was born; the Varilux. The
Varilux was developed by Bernard Maitenaz and produced by the Societe des Lunetiers
(Essel) known today as Essilor. The first Varilux used a spherical near and distance
section with an aspheric intermediate corridor that gradually changed in profile from the
distance to the near. This design was crude but effective and is the basis for many of the
modern designs seen today.
Fitting Method
Many manufacturers have fitting criteria available for their lens designs, however a good
technique to follow is outlined below:
1. Have patient chose frame, making sure the frame is fit close to the face with
10mm -14mm of vertex distance.
2. Adjust the nose pads to the patient’s nose. Apply 5°-10° of face form, and 10° –
15° of pantoscopic angle to the lenses.
3. Sitting directly across from the patient, aligned so that your eyes and the patients
eyes meet on a plane parallel to the floor, mark the centers of the pupils on the
demo lenses or a piece of clear tape placed across the frame.
4. Measure the distance from the pupil center on the lens to the inside bevel of the
bottom most portion of the eye wire. This is the segment height to specify for the
lens.
5. Use the manufacturers cut out chart to verify that the DRP, NRP, PRP are
properly placed and within the confines of the frame.
6. Take monocular IPD with a corneal reflex pupilometer. It is important to take an
accurate measure for correct placement of the optics.
Soft vs. Hard Design
Progressive lens designs have been classified as hard or soft in the past with the newer
generation of lenses exhibiting characteristics of both. Soft lenses are described as lenses
where the astigmatism from the corridor is allowed to creep into the top distance portion
of the lens or the bottom near portion of the lens. This allows the corridor to appear
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