INSTRUMENTS: Product Roundup

Low-Tech Eye Tools Make a Difference

Often the most overlooked diagnostic tools in the office, low-tech devices
are often the workhorses in ophthalmic settings.

By Gerry Navarrete, COMT

In the modern clinical setting, eyecare professionals (ECPs) rely on many computer-driven instruments. In fact, they have become so commonplace that ECPs tend to forget those simple, analog, non-digital instruments that are so vital to the operation of the office-what you might call the "not-so-electronic essential instruments." These are the devices you use on a daily basis. Without them, it would be impossible to serve patients.

Occluders
An occluder helps to block the vision of the eye that is not being tested. Designs range from a simple black paddle occluder to a lorgnette multiple-pinhole occluder. The patient holds the occluder over the eye not being tested to free the ECP's hands for other tasks. Occluders are also used to check eye muscle alignment when doing the cover/uncover test. With the help of either loose prisms or a prism bar, the ECP determines the amount of eye muscle deviation. You'll find occluders offered by many companies including Wilson Ophthalmic, Lombart Instrument, and Gulden Ophthalmics. 

Check My Pupils
One of the easiest tools to check for the pupil's reaction to light is a penlight. ECPs usually carry one around in their pocket. Most penlights are disposable and emit a beam bright enough to quickly assess pupil function.

Stepping up a little on the technology ladder, a transilluminator provides a focused brilliant beam of light that can be used to check pupil size, pupil function, anterior chamber depth, and muscle function. These handheld units use a standard battery handle into which the bent, tubular transilluminator is attached. The base is often used for other instrument heads like an ophthalmoscope or retinoscope. Companies like Veatch Ophthalmic Instruments, Welch Allyn, and Heine USA carry transilluminators.

Retinoscopes
When used with loose trial lenses or a refractor retinoscopes allow ECPs to determine nearsightedness or farsightedness. By flashing a light across the patient's eye and observing its reflex, an experienced retinoscopist can guesstimate astigmatism power and axis. The features on these instruments vary a bit and come in streak or spot configurations. The addition of a halogen bulb helps make the instrument's light intensity brighter. Check out the retinoscopes offered by Welch Allyn and Stereo Optical, Inc.

Anterior Segment Examination
The tried-and-true method of examining the front of the eye with magnification is by using a slit lamp biomicroscope. This invaluable instrument is a workhorse of the ophthalmic office. Great optics and the ability to focus a beam of light in a variety of ways helps the ECP recognize pathology, hunt for foreign bodies, and view ocular disturbances under high magnification.

With the use of handheld lenses in front of the slit lamp beam, indirect ophthalmoscopy of the fundus can be conducted. Other specialized lenses coupled with mirrors give the ECP a view of the iris to aid in gonioscopy. Look to Kowa Optimed Inc., Marco, and R.H. Burton, Co. for slit lamps, and Volk Optical., Inc. and Haag-Streit USA for handheld and gonioscopy lenses.

Posterior Segment
Ophthalmoscopes are used to view the retina. A direct ophthalmoscope gives a limited view of the retina, while indirect ophthalmoscopes allow a wider view by coupling the use of a 20.00D lens through a dilated pupil. Battery-operated binocular direct ophthalmoscopes provide a modern tangle-free solution. Heine, Welch Allyn, and Keeler Instruments, Inc. produce ophthalmoscopes.

One ophthalmoscope that differs from the rest is Welch Allyn's PanOptic(tm). The first thing you notice about it is its shape, which looks more like a monocular telescope than an ophthalmoscope. Its patented Axial PointSource(tm) Optics make it easier to enter small pupils and provides a dramatically wider, more panoramic view of the fundus that's five times larger than standard instruments in an undilated eye.

Tools for Rxs
Opticians appreciate when the prescriber provides them a vertex distance reading on a refraction for spectacle prescriptions that have a power of +/-7.00D or more. A vertex distance reading is obtained using a distometer. This simple, mechanical handheld device looks like an elongated right triangle with an indicator pointer and a plunger button on it. The tip of the device also has a moveable foot. It is positioned behind a pair of glasses so that its upper tip touches the central back surface of a lens. Pressing the plunger button activates the moveable foot. Once the patient's eyes are closed, the moveable foot is positioned onto the closed eyelid and the reading is taken. Distometers are sold by companies like Franel Optical Supply Co. and Wilson Ophthalmic.

The lens clock is another handy tool used with prescription spectacles. The device measures the dioptric curvature of spherical and toric lens surfaces. About the size of a dollar coin, the clock's face is marked with diopters of curvature around its circumference. Red numbers indicate minus curvature while black numbers indicate plus curvature. The clock has three pins that are placed perpendicularly to a lens' surface. If the lens is a sphere, the reading is easily read off the clock face. If it's a cylinder surface, the lens is rotated so that the strongest and weakest curvatures are indicated. Look for lens clocks from companies such as Western Optical Supply and Sadler Optical Tools and Findings.

These everyday instruments may be the simplest technology in your office, but they get used often. Imagine how impossible it would be to do your job without them!

Gerry Navarrete is a certified ophthalmic medical technologist employed by Southside Eye Care in Chesapeake, VA.

A Finger-Free Solution
Wilson Ophthalmic's Eyegenie® is a multifunctional instrument that can be used by patients or eyecare professionals to control eyelid positioning. The tweezer-like device is a safe, hygienic, way to hold lids wide open without the use of one's fingers. Patients find it particularly helpful in keeping their lids open to aid in eye drop instillation or contact lens insertion. The device works by using soft, delicate disposable tips that keep lids safely retracted. Eversion of either upper or lower lid is achieved by simply leaving out the opposing tip.

Conveniently Compact
Both OptiSource International and Armstrong Optical Services Co. carry the Rosenbaum Pocket Screener-a near card with multiple functions. The front side provides a visual acuity reading. This reading can be recorded in traditional Snellen notation or Jaeger notation. Acuity can be obtained using numbers, the Snellen E, or X's and O's. The front of the card has a handy pupil diameter gauge, while the back side features an inch and millimeter rule. How easy and complete!

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