Introduction: Measure Your Own Pupillary Distance
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Step 1: Conventional Wisdom
Since I live in a place where this information is impossible to get from your eye care practitioner or standard dispensary. alternate methods must be sought out.
The Pupillary distance is meant to show the distance from the centre of
the pupil to the centre of the eyeglass frame. The standard ruler measurement does not account for the asymmetry of the wearers face. Most will never see a difference but with stronger prescriptions it can be noticeable.
Normally one would use a ruler to measure the spacing, this however is not always accurate. You are able to change this measurement simply by focusing closer or farther away. In my case I would have to have someone else measure for me since I am unable to see well enough without my glasses to get the measurement myself.
There are various inexpensive "measuring glasses" available but these all fall victim to the same focal distance skewing your results problem...
I noticed that if you close one eye and hold a flat surface in line with your vision, you can see the trailing edge unless you are looking at it straight on.
Step 2: Parts Assembly
I created a simple sliding caliper device which not only gives the overall PD but can also give the individual distance to the centre of the nose.
A 3D printer with the capability to print a .25mm layer thickness was used to test this caliper.
There is no ruled scale and one will have to be provided for numeric readings.
The main body has a scooped edge which is meant to go towards the face. The opposite side has writing which reads "AWAY FROM FACE"
The indicators have a hooked shape which is meant to go downward towards the nose piece as shown.
One slides on from either side.
The support arms press into the square holes on the ends of the main body.
It is important to make sure that they do not spread outward while on your head, this will bend the main body and produce incorrect readings.
Step 3: How to Use
Each eye is aligned separately. you must close the eye that you are not aligning.
The Indicator pieces have 2 points on the lower edge.
The point closest to the eye is just inside of the focal range and should provide a halo type point. The point farthest away will be visible only when it is not perfectly aligned with the first. You can gently lift the entire frame and the farther point will be visible within the halo of the first.
When you have the first eye aligned repeat this process with the second.
There are 3 points on the top of the frame.
Measure indicator tip to tip with a ruler to get your overall PD
Measure indicator tip to centre tip to get you individual PD for each eye. Note that OD is right eye and OS is left eye.
If you do not have access to a 3D printer I do have some kits available on my website.
Runner Up in the
Assistive Tech Contest