Most optical offices still use a manual lensometer. These little gems have served ECPs for many decades but modern instruments are taking their place. Some units are simply computerized lensometers that provide highly accurate power reading. Other units go far beyond this by analyzing the entire pair of eyeglasses, providing a lot more than power readings. These instruments might be called lens and eyewear analyzers. They are simple to use and provide a wealth of information, all at the push of a button. Here’s a look at what they can do.
1. After making sure lenses are clean, the operator places the eyewear into the instrument. The special assembly in the bridge area ensures proper frame centration and alignment as well as a steady grip. Pushing the button activates the instrument’s reading and analysis functions.
2. After reading each lens, the instrument displays a wealth of information about this progressive lens eyewear. Notice the contour plots of the lenses. The sphere, cylinder, axis, and add powers are also displayed for each eye. Power accuracy can be chosen in 0.01D, 0.12D, and 0.25D steps. Optical center locations are illustrated monocularly and binocularly. Data can be sent to your practice management software or printed by the unit.
3. Notice how the contour plot of these single vision eyeglasses differs from the progressive pair. The gray zone represents the area around the optical center. In addition to powers and axis, the graphic in the center illustrates 8.5mm of vertical prism. Once the operator inputs the patient’s PD, vertical prism values will be displayed.
4. After inputting the PD, the instrument displays the prism values for each eye. Prism can be displayed in horizontal and vertical values (Cartesian coordinates) are as polar coordinates (prism value and the meridian of the base). Notice that PD values are now displayed.
5. This set of eyeglasses has bifocal lenses that contain vertical prism. The optical center placements are slightly different and the lens powers are nearly the same. Notice how the flat-top segment is imaged on the screen.
6. Once the PD information is entered (30mm for each eye), decentration and prism data are displayed in addition to power information. This pair’s prism information is displayed in polar coordinates indicating prism power and the meridian in which the base falls.
Having a lens and eyewear analyzer makes reading lens power and obtaining optical information a one-button operation. For new employees, this can be invaluable to increasing their confidence that they are getting precise information. For seasoned professionals, an instrument like this can save a lot of time.
Ed De Gennaro is Director, Professional Content of First Vision Media Group.