LENSOMETER SPECIFICS Traditional manual lensometers simply read powers and indicate prism values. Automated and
Using Gerber Coburn’s Dimetrix, even an employee with little training will be able to determine if the job meets the proper standards.
computerized lensometers provide power and prism readings in digital display form and may have a few extra features such as the ability to measure PDs on finished eyeglasses. The latest innovation in this category, lens inspection systems, do almost everything for the verification and layout process. With all these choices, the question you may ask yourself is, “What kind of lensometer do I really need?”
The answer depends on several factors. For example, how experienced are the staff members in your practice? Do you want or need a higher degree of accuracy when reading lens parameters? Is it important to have a printout of the powers of the lenses? Would it be helpful to have the lensometer reading transferred directly to the doctor’s refractor and to your electronic medical records? Do you want your lensometer to automatically perform most of the lens verification and layout work?
EXTREME ACCURACY Typically, most manual lensometers have power indicator marks on their power drum in eighth diopter units (0.125D) under +/-3.00D. Over +/-3.00D, they indicate quarter diopter (0.25D) increments. This means that if a power falls in between the quarter marks on a power over +/-3.00D, you have to judge what the power is.
If you want to increase your accuracy, you’ll need an automated lensometer or lens inspection system. These units report powers in 0.25D, 0.125D, and 0.01D units. You may not think that 0.01D readings are needed in your practice, but with the increase in free-form progressive and atoric/aspheric lenses that have powers accurately produced to 0.01D, you’ll find this accuracy increasingly more helpful.
A green light reading beam on Topcon’s CL-200 autolensometer from Topcon enhances measurement precision.
Some eyecare professionals are not as proficient as others when it comes to measuring, verifying, and laying out prism. By having an automated lensometer or lens inspection system, you can virtually eliminate the guesswork of either prescribed or induced prism.
MANUAL LENSOMETERS If you are looking to upgrade your old lensometer and don’t feel you need automated features, you may want to consider a unit such as Topcon’s LM-8/8E Lensometer. It has an improved optical system with an LED-illuminated target that gives you glare-free viewing. The instrument also offers a prism compensator, a cartridge-type marking device, and a high- and wide-field eyepiece that is less fatiguing when neutralizing many pairs of glasses.
Another manual lensometer you may consider is the ML1 Manual Lensometer from Reichert, Inc. It features LED illumination that is cool running. The LED is an energy-efficient light source that delivers a clear green target. The ML1 uses little power and has an auto-sleep feature that ensures long battery life.
Both of these lensometers are battery operated and completely cordless. This gives you the freedom to place the lensometer anywhere in the office without the inconvenience of a power cord.
AUTOMATED LENSOMETERS The popularity of automated lensometers is increasing because they come with time-saving features such as a built-in printer which saves the time needed to write down an Rx that has been neutralized. A built-in printer also helps eliminate errors (since technicians sometimes copy the wrong Rx power), and it provides paper documentation of the Rx for the job tray and/or for the patient’s record. Most units will also calculate the PD of the finished eyeglasses, a very valuable feature for a good number of offices.
Both of these features are helpful during final inspection and verification. A majority of units will also automatically neutralize progressive lenses. For example, Topcon’s CL-200 Computerized Lensmeter provides progressive lens measurement, a large color LCD monitor, and a new green light reading beam that enhances measurement precision because it automatically compensates for the Abbe value of the lens.
Another automated lensometer is Reichert’s AL500 Auto Lens-ometer. The AL500 incorporates all of the features you would expect in an autolensometer, as well as a color display, auto add-lock, and built-in printer. It’s quick and accurate, and its ease of use reduces the amount of staff training necessary.
LENS INSPECTION SYSTEMS The most advanced way to inspect and lay out lenses is to use a lens inspection system. These systems are designed to provide automatic lens power and parameter analysis, and some will also automatically block the lens. They are also capable of determining the type of lens you’re working with, including single vision, segmented bifocal, trifocal, and progressive lenses.
Topcon’s EZ-200 Automatic Lens Analyzer is a sophisticated and easy-to-use system. It automatically reads lens powers including the sphere, cylinder, and axis. It can recognize and measure single vision, bifocals, and progressives too. The unit will display far and near point distances on a large LCD screen from the optical center for progressive lenses, and it will measure monocular and binocular PDs of the finished glasses.
The ML1 Manual Lensometer from Reichert uses little power and has an auto-sleep feature that ensures long battery life.
Lens inspection systems that also block can be very handy, especially in a busy practice. They save time by automatically aligning the axis of a lens and orienting it for blocking. It can do this on single vision, segmented multifocals, and progressive lenses. Because they automatically determine the manufacturer’s markings on progressive lenses, there is no need to add new marks. This is especially handy for today’s super-hydrophobic lenses that can be challenging to write on.
Lens inspection systems of this caliber also help improve consistency because of their accuracy and because there is less handling of the lenses, which also helps to reduce spoilage due to scratches and lenses blocked off-axis.
One popular lens inspection system and finishing device is Gerber Coburn’s Dimetrix that utilizes two advanced technologies, Wavefront powerMap® for lens power analysis and image recognition for extremely precise lens blocking. When integrated into the lens-finishing process, Dimetrix decreases manual inspection and blocking operations while reducing skilled la-bor and rework costs. Using ANSI standards, Dimetrix analyzes the lens and then indicates whether the lens is in or out of tolerance. Using this device, even an employee with little training will be able to determine if the job meets the proper standards.
The DS-7000 from Topcon is another lens inspection system and layout blocker that allows for minimal training for processing lenses. You simply place a lens on the layout table, select left or right lens, and the unit automatically executes the proper decentration, finds the optical center and axis for single vision lenses, locates the segment of bifocal lenses and the ink or hidden markings for progressive lenses, and blocks the lenses accurately.
These units allow the user to choose either a touch screen or bar code reader for all data entry. Operators simply type in or scan the job number to retrieve job information from a host computer.
CONTACT LENSES Have you ever had a patient ask you which of their contact lenses is correct for each eye? You can neutralize them with CBD/TOMEY’s TL-2000B. The unit has the proper lens stop to support gas permeable contact lenses. And if you need to find the power of a soft lens, simply select the dry mode and read the lenses.
Once you determine if you need the basics of a manual lensometer, the automation of a computerized lensometer, or the advanced capabilities of a lens inspection system, then you can begin selecting from among the various devices available in each of these categories.
Kenneth N. Johnson is the Optical Manager at Barri Eyecare Center in Groton, CT.
WHERE TO FIND IT CBD/TOMEY 888-449-4045 • tomeyusa.com
Gerber Coburn 800-843-1479 • gerbercoburn.com
Reichert, Inc. 888-849-8955 • reichert.com
Topcon Medical Systems 800-223-1130 • topconmedical.com
