see anything you like? 

How Glasses Are Made

Lenses in your glasses bend light in a manner which brings the light to a focus inside the eye on the retina. Once the proper lens has been prescribed, glasses can be ordered. The lens is the important part here, and frames must be selected which will properly hold the prescribed lens.

For our purposes here we will show how the simplest of lenses are fabricated. The single vision lens has constant power throughout the lens – there are no variations as there are in bifocals or progressive lenses. The lens here is a stock lens; it already has power and is ordered from stock – it is not a custom made lens. Most bifocals and progressives are “surfaced lenses”; this means we order it custom made from an optical laboratory. When it comes to us, it may look just like the stock lens – it is then “cut” here in our laboratory.

The first step is to align the lens in the lensometer to properly account for prescribed astigmatism and to mark the optical center of the lens.

The lens is then placed in a centrator which allows us to align the lens perfectly and place a blocking pad over the optical center. The blocking pad will hold the lens when it is placed in the edger.

The frame to be used is placed in the “tracer”. The tracer has a stylus which travels around the inside of the frame tracing it’s contour. We then have a picture of the lens shape which is accurate to fractions of a millimeter. The picture on the screen of the edger allows us to place the optical center of each lens directly over the pupil of each eye. Inaccurate placement of optical centers can be a cause of visual discomfort (asthenopia).

The edger then cuts the lens to the desired shape. When the lens is removed from the edger, the edges of the lens are sharp; the lens is then hand beveled to smooth out the edges.

The lens can then be scratch-resistant coated, UV coated, tinted or edge polished before being inserted into the frame.

Lenses

There are many types of lenses, the most common of which are single vision lenses, bifocals and progressives. Bifocals and progressives are used when there are different prescriptions for distance and near viewing. The lens is then required to have one prescription on the upper portion of the lens and another prescription in the lower portion. The lower portion is almost always the area used for near vision.

If the change in power is abrupt, there is a definite line or circle created where the power changes. This is what exists with the round seg, or Flat-Top Bifocal.

If the change in power is gradual, as it is in progressives, there is no visible line. The other advantage of progressives is that by tilting the head to look through different parts of the lens, one can focus for any intermediate distance as well as close up.

Most lenses can be made of glass, plastic or polycarbonate. The most popular is plastic. Plastic lenses are available in with different indexes of refraction – so they can be made thinner then conventional plastic. Polycarbonate lenses are more protective than glass or plastic lenses. Polycarbs are used for children, sports glasses and for monocular patients. Contrary to their advertising, they are NOT “only available at LensCrafters.”

The most common add-ons for lenses are simple tints, reflection-free coating and polarization.

Reflection-free coating rids the lens of un-wanted reflections. Glasses are more cosmetically pleasing and vision is enhanced by less distractions caused by reflections. In most of Europe, reflection free coating is required by law if you drive at night. The down-side of this coating is that it must be kept very clean. Fingerprints, smudges and dirt are much more visible on these coated lenses.

Polarization eliminates reflected glare off of a horizontal flat surface. It is particularly effective on the water. For example, if you are looking West in the afternoon, the sun causes significant reflections on the water. Regular sunglasses will dull the reflections, but polarized glasses will virtually eliminate them. This add on is also valuable in bright sunlight on a wet road or on a sunny day on the snow.

Frames

We feature what may be one of the largest frame selections in a private setting on Long Island. Frames are priced from roughly $ 95.00 to $ 325.00. Our designer lines include, but are not limited to the following: