Clinical Consult
The Art and Science of Low Vision
Finding the right device to help your patient see his best.
BY STEVEN I. BENNETT, O.D., F.A.A.O., Ann Arbor, Mich.

Practicing the art and science of low vision treatment requires more than a degree. Low vision doctors are part psychologist, sociologist, scientist, magician and miracle worker. We're usually the patient's last hope -- a grave responsibility.

Luckily, the variety and technological advances in low vision devices help us help our patients. Here, I'll give you some background and explain what's out there for low vision patients.

The personal touch

The methodologies used to pick a device for a given patient are as numerous as the patients. We all have different formulas for prescribing and tend to use devices that we're familiar with and that provide the best results. I'll mention the devices that I use most, but many other wonderful devices are available.

The cost of a low vision device doesn't dictate its success. Less expensive devices can do wonders. Try more than one device for a given task. Give the patient the opportunity to work with several before choosing the one to prescribe. The success of low vision treatment hinges on your knowledge of the devices, your imagination and the time you spend with the patient.

Doc, I just want to be able to read the newspaper!

Low vision devices are usually successful for reading and for close work. Here are some examples in this category:

Prismatic half eyes. Patients who are still binocular and whose magnification needs are no greater then 3.0X can do well with prismatic half eyes. These devices are readily available and aren't expensive.

Lighthouse Low Vision Products carries a wide range. Luzerne Optical will incorporate an astigmatic correction into its prism half eyes. Chadwick Optical has introduced a more upscale line of prismatic glasses with metal spring hinge frames.

The Clear Image reading system. When the patient isn't binocular and the needed magnification is 2.0X or greater, the Clear Image reading system from Designs for Vision is useful. The lenses aren't as thick as the prism half eyes and the optics are nice.

Telephoto lenses. In extreme cases where 8.0X or greater magnification is desired, Designs for Vision also makes a telephoto lens system. The manufacturer mounts these lens systems in spectacle frames, which are usually supplied. Patients appreciate the cosmetic appearance of these systems even though they have to hold their reading materials much closer to their faces.

Reading telescopes. When the working distance must be increased, a reading telescope is appropriate. Designs for Vision has reading telescopes starting at 2.0X that incorporate the patient's prescription and working distance. Expanded field models are also available.

Eschenbach makes a less-customized series of small, lightweight reading telescopes. The field of view is reduced, and patients need to be able to hold their reading material steady, so a reading stand is helpful.

Remember that lighting is critical for success with any of these devices as well as for performance of simple tasks around the house and at work. I recommend an adjustable stand or desktop gooseneck lamp with an internal reflector insert. A 60-watt or lower incandescent bulb works well and is inexpensive. Using these lamps for tasks such as cooking and hobbies, even without low vision devices, can sometimes make a world of difference. But make sure there's no glare to interfere with the patient's vision.

Magnifiers for reading

Magnifiers also play a major role in improving reading ability. Hand-held magnifiers work well for spot reading telephone books, medicine bottles and restaurant menus.

Stand magnifiers require no focusing and are used when reading on a flat surface. These aren't as compact as the hand-held models, but they work well for higher amounts of magnification. You can order these with a plug-in attachment for extended use.

The optics of magnifiers vary. I suggest using high-quality systems. I like those from Eschenbach and Optelec. The latter offers a lifetime warranty on their products and a toll-free number for consumers.

You may choose lighted or unlighted magnifiers. I prefer the lighted systems. Magnifiers are frequently used in conjunction with other reading systems such as the following to provide the patients with a number of options to perform specific tasks.

Electronic reading systems. The exciting closed-circuit television (CCTV) systems from Telesensory, Optelec and others have become sleeker in design and user-friendly. Features include zoom lens magnification, focus and picture controls -- black background with white letters or white background with black letters. Patients can read the newspaper, write checks and view photographs and 3-D objects with these devices. Magnification of printed material can be up to 2 inches. These systems aren't portable and don't fit into a patient's pocket when he leaves home. However, manufacturers are continually improving design and optics.

Portable systems. Newer, more portable personal reading systems combine mobility, diversity and autofocus capabilities. Here are some examples:

Enhanced Vision Systems (EVS).

The Max digital hand-held magnifier. This features a mouse-like camera that you can connect to any television. Magnification ranges from 16X to 28X, depending on the size of the television. Units are available in black-and-white or color. They're easy to use and to set up.

A unique attachment to this system is MaxPort glasses. You can connect these lightweight glasses to the Max digital hand-held magnifier instead of a television monitor, giving the patient total self-containment. However, patients can't use these systems for writing tasks.

Jordy. Recently, EVS launched Jordy, the all-in-one low vision system that enables low vision patients to see objects at distance, up close and at any range in between. Patients may wear this lightweight, battery-operated system like a pair of glasses or use it as a desktop CCTV when placed on its docking stand. It's also possible to watch television through it.

Jordy has a magnification range from 1.0X to 24 X and full-color, auto-focus functions. Patient education and training are important for getting the maximum benefits from Jordy.

Ocutech.

The Ocutech VES-AF. This was the first autofocus system for low vision use. The VES-AF is worn attached to the top of a pair of spectacle frames that also contain the patient's regular eyeglass prescription. Its light weight allows it to be worn comfortably for hours.

A separate, rechargeable battery pack operates the system for the entire day. The 4.0X power magnifies objects from infinity to 12 inches. The autofocus mechanism is smooth and rapid.

Some technological improvements are still needed in all autofocus systems, but they've created a new era in low vision treatment and opened up numerous possibilities for our patients.

Doc, any chance of seeing my computer better?

You may find that providing devices for mid-range tasks is frustrating. Unfortunately, more patients are using computers, and the demand for mid-range vision is increasing. However, computer eyeglasses work well when magnification require- ments are minimal.

These glasses can help patients see objects in the 12-inch to 22-inch range. The patient's working distance determines the prescription. A focusable, 1.7X Spiral Galilean Telescope from Designs for Vision can meet greater magnification needs. This scope provides a 20-degree field of view and enough magnification to view the screen and other objects. Higher powers are available with the appropriate reduction in field of view.

Beecher has a new 5.0X system for computer use. It weighs 3 ounces and has a 12-degree field of view. The focal range is fixed at 17 inches.

Some autofocus devices, like the Jordy and the Ocutech VE-AF, have capabilities for computer screen viewing. Many large-print computer access hardware and software products are also available for patients.

Doc, I can't see faces!

Despite the abundance of distance low vision devices, patients must acquire some skills to use them because the reduction in the field of view can confuse them. Consider these hints:

• Always explain the use of the device before the patient tries it for the first time.
• Watch for tremors and other physical problems that might hinder the use of any hand-held device.
• Have an updated refraction before using the devices on patients. Sometimes a change in a patient's prescription can in-crease the effectiveness of the low vision device.

Along those lines, the Maculens system of improving visual acuity has recently been introduced to some low vision specialists. The eyewear consists of a doublet or two-lens system. The frame assembly is a compact, hinged frame that holds two sets of lenses.

The front set holds the patient's complete prescription -- single vision or bifocal. The back set contains patented prisms. The space between the lens sets is 1.2 mm to 1.5 mm. The idea is to test the patient's distance and near acuity by placing prisms in front of the Maculens trial frame.

The prism moves the images away from the macula. Generally you can find a spot adjacent to the macula that has an improved visual image. The amount and direction of the prism is incorporated into the patient's prescription. This isn't a new concept, but a better way of prescribing rotating prism.

Here are some examples of low vision devices for distance.

Distance telescopes. Telescopes come in all shapes, sizes and powers.

Hand-held telescopes. Most companies have many hand-held telescopes, which are great for spotting signs, cars and people and are versatile enough to carry around. Powers range from 2.0X to 12.0X.

The Nikon 6.0X monocular. The optics are great, field of view is 7.5 degrees and it's light-weight. It works great in the classroom.

The Zeiss Mini Quick telescope. This is also portable and useful in the classroom.

Head-borne telescopes. These telescopes are used for more permanent viewing periods and set the patient's hands free because they can wear them like glasses.

Galilean telescopes. Eschenbach has a 1634 series of binocular Galilean telescopes in an adjustable frame for distance viewing and watching television (see page 94). Monocular systems are also available. Good optics, pupillary distance adjustment and a field of view of 9.5 degrees make this a nice system.

Mattingly. Mattingly has a less sophisticated 2.8X head-borne telescope with a 12-degree field of view for lower magnification needs.

The Beecher Mirage telescopes. These offer powers from 3.0X to 8.0X. The field of view is generous, with a 15-degree field in the 4.0X model. The optics are great. Adjustments are critical for optimum perform-ance and comfort. The higher the power, the more skill patients need to feel confident.

All of these autofocus systems have distance capabilities. Patients can't walk or drive while wearing these systems, except for the Ocutech VES-AF.

Mobile systems

When mobility is an issue, you need bioptic telescopic systems. Lightweight telescopes are mounted in spectacle lenses above the line of sight or on top of the frames. These systems are individually made and incorporate the patient's prescription in both the telescopic objective and the carrier lens.

Mobile systems are used for spotting -- the patient can travel with them. To see a distant object, the patient lowers his chin and looks through the telescope.

Driving scopes. Some states allow patients to drive using bioptic telescopic systems. Each low vision specialist has his own comfort level about under what circumstances to prescribe a telescope for driving. Know your patient and his limitations.

I use Design for Visions and Ocutech. Bioptic telescopes are widely used in schools and for daily living needs.

Scopes for cosmetic considerations. Ocutech telescopes are mounted on top of the spectacle frame, so little protrudes from the glasses themselves. Bioptic systems can be custom-made to include bifocal or trifocal lenses or other telescopes. Designs for Vision will work with you to design the perfect device.

Light hurts my eyes!

Glare is a low vision patient's nightmare. It can create "fuzz" that constantly obscures vision; eyes water, too. Contrast is diminished and detail vanishes.

Sunglasses can eliminate glare but reduce ambient light. The answer? Corning Medical Optics has created photochromic lenses that filter blue light. Corning provides a frame, or patients can use their own.

The range of lenses permits indoor, outdoor and computer use. Glarecontrol lenses (see page 96) look great and can improve overall visual acuity even in a plano design. When patients don't respond well to other low vision devices, they may to Glarecontrol lenses.

NOIR Medical Technologies makes UVShield glasses, polycarbonate lenses available in infrared, ultraviolet and blue-light absorption. Patients may wear them alone or over pre- scription glasses.

Test glare control systems on every low vision patient. They can provide visual comfort, clarity and increased contrast.

Last resort

Be prepared for low vision patients to be angry, sad, depressed, hostile -- and grateful for help. Although we can't help all of them, emerging technology and medical research have reduced the numbers of those whose vision we can't improve.

Patients need a last resort. They need us to evaluate their ability to function in the world, educate them on what's available and then help them see.

Dr. Bennett has been in group practice in Anne Arbor, Mich., for 23 years, concentrating on low vision and contact lenses. Past chairman of the Michigan Optometric Low Vision Committee, he lectures on low vision and contact lens topics.