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Expert outlines low vision devices for primary care ODs
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“Low vision care is all about the patient’s goals,” Richard J. Shuldiner, OD, FAAO, told Primary Care Optometry News.
“To properly take care of a low vision patient, the low vision doctor must understand the visual requirements of the desired task and have a thorough knowledge of the advantages and disadvantages of low vision devices,” he said.
Shuldiner shared his wisdom on low vision, which he has acquired since the early 1970s while practicing in upstate New York and now in Southern California, during a presentation at the Envision Conference in September.
In the majority of low vision cases, magnification is the most common tool to help these patients meet their goals, and there are many options to accomplish this, he said at the meeting.
For patients who want to read, one of the least expensive options in optical devices is high add spectacles, which can be biconvex or plano-convex, he said.
High plus lenses can also be aspheric, which is somewhat more expensive but has fewer aberrations. Aspheric doublet lenses are the most expensive options, but produce the best optics, Shuldiner explained at the conference.
Because high plus lenses require a shorter working distance, Shuldiner explained how to know the focal length of the glasses prescribed. He defined the optics of plus lenses as 1/D=F in the metric system, the focal length in meters being the reciprocal of the dioptric power. So, a +8 D lens focuses at 1/8 meters, he said.
Using the imperial system, the formula is 40/D=F; the focal length in inches is 40 over the dioptric power (there are approximately 40 inches in a meter). Thus, a +8 D lens focuses at 40/8 or 5 inches, he explained.
Another option for reading that the patient may already own is the digital tablet, Shuldiner told PCON. These devices, such as Apple’s iPad or Amazon’s Kindle, allow the patient to download books, newspapers and magazines, set various levels of magnification and change the contrast settings and fonts. In addition, there are various free magnification apps that could replace a hand magnifier.
such as price tags, labels and oven dials, he said at the meeting. They are available in illuminated versions, and the optics and aberrations vary with lens type. Handheld magnifiers are to be used with distance prescriptions, not near add, as the object is at the focal length of the lens, and parallel rays emerge from the lens. Also, the higher the power, the smaller the lens diameter.
Many companies offer quality hand and stand magnifiers, Shuldiner said in the interview. Eschenbach and Optelec (part of VFO) are two examples. Hand and stand magnifiers are available in regular, aspheric and aplanatic lens types. Prices vary with quality, with aplanatic being the most expensive.
Stand magnifiers are useful for patients with hand tremors or instability. Like hand magnifiers, they are useful for near spot reading and available in both illuminated and non-illuminated versions. Unlike hand magnifiers, they must be used with the near add, Shuldiner explained.
Telescopes are another option for those with low vision, he continued. They are useful for distance vision tasks such as spotting bus numbers or street signs. Handheld options are usually monocular, focusable and available with 2x to 20x. They are inexpensive but can be inconvenient, and a patient must have good hand-eye coordination to use them.
Telescope spectacles come in prescription and ready-made versions with bioptic and full diameter options, Shuldiner explained. Prescription telescopic spectacles are more complex and require more experience to fit. They are useful for driving, watching television, playing cards and other intermediate or distance tasks. They can be converged for near work, as well.
Many low vision patients require a team of specialists to remain independent and have a good quality of life, he said.
“The low vision optometrist should be the leader of the team, which may include many other disciplines,” Shuldiner told PCON. “Who participates depends upon the patients’ requirements.
“For example, if the low vision optometrist determines that a glaucoma patient’s mobility is an issue due to peripheral vision loss, the patient would be referred to an orientation/mobility instructor to learn navigation techniques for safe travel,” he added.
While he works as a solo practitioner, many professionals are available for referrals when necessary, Shuldiner said.
“It is time for eye care professionals to stop telling patients ‘Nothing more can be done,’” he told PCON. “Referral for low vision services is an idea whose time has come.”
The American Academy of Ophthalmology has declared that referral for low vision rehabilitation is now the standard of care for patients who have lost vision, he added. – by Abigail Sutton
Reference:
Shuldiner R. The low vision evaluation: What’s available to prescribe. Presented at: Envision Conference; Sept. 7-10, 2016; Denver.
Disclosure: Shuldiner reports no relevant financial disclosures.