Posts Tagged ‘individual lenses’

Read On If You Have Night Vision Trouble

Friday, February 17th, 2012

Nothing is perfect, including your eye.  As light enters the eye it is altered by imperfections in the cornea, lens, vitreous, and retina.  We refer to these alterations as aberrations and the vast majority of aberrations are caused by the front surface of the eye called the cornea.

Most aberrations are typical and refractive in nature such as nearsightedness, farsightedness, and astigmatism.  These are called low order aberrations and can be compensated for with ordinary eyeglasses and contact lenses.

Other aberrations are less typical such as coma, trefoil, and spherical aberration.  These cannot be compensated for with ordinary glasses and contact lenses and are called high order aberrations.

We can now measure many of these aberrations with an instrument called an abberometer.  I find that about 10 to 20 percent of people I measure have significant nighttime higher order aberrations.  If you have night vision trouble you probably have significant higher order aberrations under low light conditions and you should be measured!

Based on these advanced measurements a pair of custom eyeglass lenses (free form/individual lenses) can be made to compensate for both your low order and higher order aberrations to improve acuity and contrast; especially in low light or nighttime conditions.  At this time we are not able to compensate for all higher order aberrations, but our abberometer has a simulation mode which can accurately predict who is able to benefit from this new technology.

By Dr. Cook, O.D.

I Wish I Could See Like Superman…

Monday, March 14th, 2011


Have you or someone you know had trouble adapting to progressive lens in the past?  It may be time to try a new easy to adapt to digital lens.  Free form digital lenses are the latest design improvement for progressive eyeglasses. With computer aided design, free form digital lenses combine information from corneal mapping, subjective refraction, selected frame size, and fitting geometry.  An ideal progressive lens is then computer determined on a point by point basis until a final prescription is produced that can most closely match an ideal lens.

Design Differences:

  • Designed in “real time” and customized to an ideal prescription.
  • Prescription customized for selected frame.
  • Customized for individual frame fitting geometry
  • Fits nearly any selected frame, even small styles.
  • Back-side progressive optics.

Advantages of free form digital lenses:

  • Wider field of vision (up to 50%)
  • Reduced distortion
  • Less image magnification leading to less dizziness (25%reduction)
  • Easier adaption

Learn more about free form digital lenses and schedule an appointment today. Gray Family Vision has two greater Portland Maine locations to serve you in Gray and Windham.

By Dr. Cook, O.D.

Digital Progressive Lenses.

Monday, March 7th, 2011

Project 365 "Tired of Waiting"

Advanced technology  is finally available to create free form digital progressive eyeglass lenses. This post will discuss a few reasons why custom lenses may be worth waiting for.  There are two basic ways of producing progressive lenses in about an hour:

1. Casting technology is where liquid lens material is added to a mold and then exposed to UV light to form the finished lens.

Disadvantage:  At this time anti-scratch and anti-reflective coatings that can be applied in office on lenses made in this fashion are inferior in quality and they are not available in the newer free form digital style lenses.

2. Semi-finished lenses is where the progressive bifocal has already been ground on the front surface of the lens and then the back surface is ground to meet your distance prescription.

Disadvantage: The anti-reflective and anti-scratch coatings are removed from the back surface in the process leaving only the front surface coatings in tact.  Also, these lenses are not available in the newer free form digital style lenses.

Custom free form digital style progressive lenses are made possible by advances in technology that can combine information from your individual refraction (the one or two portion of the exam),selected frame , and frame fitting geometry to deliver superior vision compared to conventional progressive lenses.

Learn more about free form digital lenses and schedule an appointment today. Gray Family Vision has two greater Portland Maine locationsto serve you in Gray and Windham.