Got my 1st pair of Reading Glasses!

Last weekend, I bought my first pair of prescription glasses from the Ideal Vision branch inside SM Fairview. It was actually reading glasses for my slightly deteriorating eyesight. I have been delaying this purchase for the last year or so for what seems to be inevitable as one grows older. Years of staying up late, reading against the light and not eating enough carrots I guess have finally caught up with me. I’m sure my diabetic condition has a lot to do with it too.

So with the eyeglass prescription I got from my ophthalmologist last January of this year, I sought remedy for my blurring vision.

At the eyeglass shop, the optometrist made me underwent basically the same procedures my ophthalmologist made me go through every visit. They used the phoropter to determine which lenses were best. Even as a kid, I always liked to have my visual acuity tested through Hermann Snellen’s classic letter chart. According to the Dictionary of Visual Science, visual acuity is the “acuteness or clearness of vision which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain.”

According to Wikipedia:

In the term "20/20 vision", the numerator refers to the distance in feet between the subject and the chart. The denominator indicates the size of the letters, specifically it denotes the separation at which the lines that make up those letters would be separated by a visual angle of 1 arc minute, which for the lowest line that is read by an eye with no refractive error (or the errors corrected) is usually 20 feet. The metric equivalent is 6/6 vision where the distance is 6 metres. This means that at 20 feet or 6 metres, a typical human eye, able to separate 1 arc minute, can resolve lines with a spacing of about 1.75mm. 20/20 or 6/6 vision can be considered nominal performance for human distance vision; 20/40 or 6/12 vision can be considered half that acuity for distance vision and 20/10 or 6/3 vision would be twice normal acuity. ^[2] The 20/x number does not directly relate to the eyeglass prescription required to correct vision, because it does not specify the nature of the problem corrected by the lens, only the resulting performance. Instead an eye exam seeks to find the prescription that will provide at least 20/20 or 6/6 vision.^{[citation needed]}

If I remember it right, the good thing was I still had 20/20 vision. But my view of the chart became much sharper and better defined as a different set of lens were applied to my eyes.

This experience with corrective lenses widely broadened my knowledge with eye vision.

For instance, I realized that the prescription order consisted of all the specifications necessary to make the lens. Prescriptions generally include the power specifications of each lens (for each eye). Lenses come in positive (plus) and negative (minus) powers. Since a positive power lens will magnify an object and a negative power lens will minify it, it is very possible to tell whether a lens is positive or negative by simply looking through them.

Each power specification includes a spherical correction measured in so-called diopters. Convergent powers are positive (e.g., +4.00 D) and condense light to correct for farsightedness or to allow a person to read more comfortably. My eye doctor prescribed at the spherical column of my prescription + 1.50 for both my left (OS – Latin: oculus sinister) and my right (OD – Latin: oculus dexter) eyes. Divergent powers are negative (e.g., −3.75 D) and spread out light to correct for nearsightedness. If neither convergence nor divergence is required in the prescription, "plano" is used to denote a refractive power of zero.

In the late 90’s, I bought a pair of glasses with plano lenses. I just requested that it be UV coated because aside from its trendy look I used it while working in front of the computer. Long term exposure to UV-A radiation could damage the retina while massive exposure to UV-B radiation is said to increase the likelihood of cataracts.

For my reading glasses, my eye doctor prescribed clear, single vision lenses made of plastic material. I’m not sure so sure whether the lenses I got were plastic or glass but they were definitely clear and single vision. Single vision lenses have the same optical focal point or correction over the entire area of the lens. Other lens types include bi-focal, trifocal, progressive, adjustable focus or aspheric.

Another new thing I learned was the meaning of the acronym PD that you would probably see in an eyeglass prescription. PD stands for Pupillary Distance, sometimes also known as Interpupillary Distance (IPD). Basically it is the distance between pupils expressed in millimeters. It is often measured by the use of a pupilometer or by a classic ruler. PD measurements are said to be important in all spectacle dispensing. But I’m wondering why my previous PD was measured at 68 while in my latest prescription it was measured at 67. Does it actually change through the years?

At any rate, I’m now reaping the advantages of superb eyesight wearing my reading glasses when going through those fine print texts. Of course, I don’t wear it when I’m not reading anything close by as the lens was not meant for farther distances say more than a foot away from my eyes.

There is just one other procedure my eye doctor wants me to undergo due to my diabetes – a fluorescein angiogram. But that’s a topic for another post.

For now, I’m just thankful to God for my clearer eyesight!