As primary care practitioners, optometrists often face the difficult task of guiding patients through the life-changing visual conditions associated with age. In addition to providing the necessary treatment and devices, practitioners must also help ease a patients adjustment to the lifestyle limitations of low vision.
When confronted with a partially sighted driver, the optometrist must make ethical decisions that may profoundly affect not only the patients independence, but his or her safety and that of the driving public.
We saw a patient about 3 months ago who had retinitis pigmentosa and a 5° field, so he had the truest definition of tunnel vision, said William L. Park, OD, FAAO, a low vision practitioner based in Baltimore, Md. I initiated having his license re-examined, because I felt there was the risk that a pedestrian crossing the street could be hit and potentially killed. Not only with regard to being sued, but to continue to be able to look in the mirror, I took that action.
Optometrists have varying degrees of responsibility in terms of treating the partially sighted driver. These differing obligations depend largely upon the state in which the optometrist practices.
Thomas L. Porter, OD, FAAO, is a practitioner based in St. Louis who sees patients from both Missouri and Illinois. The state of Missouri has a progressive restriction law, he said. That means the worse the level of vision, the more restricted a patient is in terms of where and when he or she can drive.
For example, Dr. Porter explained, a patient whose vision is correctable to 20/40 or better can have an unrestricted license. A patient with best-corrected vision between 20/40 and 20/70 would be permitted to drive in daylight only. A patient with corrected vision worse than 20/70 but better than 20/120 is restricted to daylight driving in areas within a designated radius of his or her home, with a speed limit of less than 45 miles per hour.
To qualify for that restriction, they have to do a road test with a highway patrolman, Dr. Porter said. That takes some of the burden off of me in terms of making that determination.
Dr. Porter said, in Illinois, if a patients vision is worse than 20/70 but better than 20/100, the practitioner can fit the patient with a bioptic telescope. If the vision through the wide angle bioptic is 20/40 or better, we can use that as a tool to help the patient maintain his or her license, he said.
Dr. Porter said that while in Illinois the practitioner is obligated to contact the Department of Motor Vehicles about an unfit driver, there is no such mandate in Missouri. There is an anonymous hotline available for us to call, but I have never taken advantage of it myself. I never felt that I needed to, he said.
In Texas, where Kathleen F. Freeman, OD, FAAO, most recently practiced, low vision patients can get a restricted drivers license with a bioptic telescope. Their vision can be as poor as 20/200 without the telescope, and then 20/40 through the telescope, and they are eligible for a license, she said. There is a visual field requirement also.
Dr. Freeman said restrictions typically imposed on partially sighted drivers include no freeway driving, no nighttime driving and no driving over 45 mph.
Dr. Park said, in Maryland, where his practice is located, optometrists do play a role in having patients licenses revoked.
Part of our responsibility is to initiate re-examination, to make the state aware that this person is on the road and that he or she is probably not safe, he said. In the future, we are going to have more and more older adults who may not be safe to drive. I think the burden on the practitioner is going to become even greater.
At his practice, Dr. Park employs a rehabilitation teacher and an occupational therapist who assess a patients ability to use a bioptic telescope on a course located at the medical campus. Patients are required to read signs, identify traffic lights out on the street and evaluate them, he said. And if we feel they are ready, we initiate a road evaluation.
Legislative efforts to toughen requirements for senior drivers in Oregon and California failed last year, following lobbying against the bills by the American Association of Retired People (AARP).
The Oregon bill would have required drivers older than 80 to renew their licenses every 2 years, instead of 4, and to take driving and medical tests. In California, Sen. Tom Hayden abandoned an attempt to require road tests for drivers over 75 when it became clear in September that the measure lacked the needed votes.
Prescribing bioptic telescopes
The most commonly used tool to assist partially sighted drivers is the bioptic telescope. While this equipment can be extremely valuable in helping the low-vision patient retain his or her freedom, practitioners advise caution in prescribing the device.
I think a well-trained patient who has a bioptic telescope in most cases can continue to drive and do well, Dr. Park said. But there are certainly instances in which the bioptic telescope adds confusion instead of providing the tool. This can be a very complicating factor.
Dr. Park described a circumstance in which the bioptic telescope could potentially do more harm than good.
The definition of legal blindness is 20/200 or worse in the better eye. Thirty-four states allow telescope driving; all vary in required standards, he said. However, when the patient looks through the bioptic portion, the visual field is only about 4-18° depending on the type of telescope. The definition of legal blindness is also a visual field of less than 20°. So through the telescope, the persons visual field is very constricted.
Alfred A. Rosenbloom Jr., OD, chair of the Low Vision Service at the Chicago Lighthouse and a Primary Care Optometry News Editorial Board member, also recommends that practitioners prescribe telescopes carefully and sensibly.
That is one of the roles of the optometrist in the low vision field to be aware of the advantages and limitations of such a system, he said, and to counsel a patient, providing adaptive training in the proper use of a device as required by state licensure.
Dr. Freeman maintained that bioptic telescopes have great value for drivers who lack detail acuity. They are very useful for people who have trouble seeing traffic signals and reading signs at a distance, she said. Patients require good peripheral vision and good orientation in space to be able to drive safely, but the detail acuity is often a problem. That is where a bioptic telescope can be very helpful.
Dr. Park said he likes to loan a telescope to a patient for a week before prescribing it to him or her. I dont want patients making judgments about whether it helps them based on sitting in my exam room, he said. I want them to go home, watch TV with it, walk with it and use it in their daily lives.
Dr. Park said if he does prescribe the telescope, he then likes to see the patient for three to four follow-up visits over the course of 90 days. He emphasized that he refuses to prescribe telescopes indiscriminately.
Dr. Park added that he is vehemently against this type of care. I have done everything in my power to try to avoid having my patients do that: just plunk down the money and continue to drive, he said. I had an instance many years ago where a fellow was in an automobile accident, and thankfully no one was hurt. But his bioptic was sitting on the seat next to him.
Visual field: also a concern
One factor that is not always emphasized in evaluating the partially sighted driver is visual field. While some states do have visual field requirements for low vision drivers, others do not have such stipulations.
There is a wide range of visual acuity requirements, but there is a much wider disparity in visual field requirements, Dr. Rosenbloom said. One study notes that 50% of motor vehicle agencies do not specify visual field requirements for driving. Of the remaining states, 40% require binocular fields ranging from 110° to 140°, and one state requires a binocular visual field of only 70°.
Dr. Rosenbloom said he would like to see more of a focus on visual field in assessing partially sighted drivers.
One of the most important functions of peripheral vision while driving is motion detection, he said. In fact, objects that are three to 10 times smaller than those resolved by the fovea can be detected in the periphery through motion. Retaining an intact peripheral field is essential for safe driving.
In the optometric community, some practitioners have voiced concerns about the extent to which they should be involved in a patients driving privileges. Specifically, optometrists are conflicted regarding their role in having a patients license revoked, Dr. Freeman said.
There has been some discussion among optometrists about writing to the boards that issue these regulations, protesting that, she said. I think optometrists are just uncomfortable with being required to turn somebody in.
Dr. Freeman added that she believes that partially sighted drivers should be assessed based on their individual cases, and not necessarily on state regulations alone.
I think what I would like to see is that each individual be evaluated on his or her own abilities, she said. To that end, I have gotten involved in writing letters on patients behalves to the Department of Public Safety, asking them to consider the persons ability, and perhaps make an exception to the requirements.
Dr. Porter said it is also possible that a patient who meets the state standards may still be unfit to drive. There have been countless times when a person would meet the visual acuity requirements to continue to drive, but really should not be driving, he said. I have to tell them that its time to stop, to find another mode of transportation.
Dr. Freeman pointed out that while optometrists play a role in determining a patients visual capacity for driving, this is not necessarily an indicator of how a patient will react on the road.
All we can do is make statements about the patients visual ability as we measure it clinically, she said. We then ask for the motor vehicle department or the department of public safety to further evaluate the patients ability to do the task. That is the entity that issues the drivers license in the first place.
For Your Information:
William L. Park, OD, FAAO, can be reached at 600 North Wolfe St., Baltimore, MD 21287; (410) 955-0580; fax: (410) 817-9504.
- Thomas L. Porter, OD, FAAO, can be reached at 1755 Grand Blvd., St. Louis, MO 63104; (314) 577-8258; fax: (314) 771-1359.
- Kathleen F. Freeman, OD, FAAO, can be reached at 165 Backbone Rd., Sewickley, PA 15143; (412) 749-2497; fax: (412) 749-2417.
- Alfred A. Rosenbloom Jr., OD, is chair of the Low Vision Service at the Chicago Lighthouse. He can be reached there at 1850 West Roosevelt Rd., Chicago, IL 60608-1298; (312) 666-1331; fax: (312) 243-8539; e-mail: email@example.com.