Letters to the Editor Can Visual Acuity Measurements Predict Ability to Drive Safely?
The following letters concern the lead article and editorial from the October 1989 issue of The Journal.
Fonda and Lichter have broached a subject which deserves further investigation as to the true functional abilities of patients with visual loss. The ophthalmologist's responsibility to these individuals and to the public at large requires definition. MARCEL FRENKEL, MD, MBA Chicago, Illinois
Fonda G. "Legal Blindness Can Be Compatible with Safe Driving" (Ophthalmology 1989; 96: 1457-9).
Author's reply
Lichter P. "The Ophthalmologist's Role in Licensing Drivers" (Ophthalmology 1989; 96:14556 [Editorial]).
Dear Editor:
Dear Editor: The article by Fonda and the accompanying editorial by Lichter highlight concerns which trouble the undersigned and likely many other practitioners. Fonda suggests that some patients with visual acuity less than 20/200 may drive safely given a minimum visual field of 120°. Several questions arise regarding the ophthalmologist's role in driving licensure. The above-referenced items discuss the situation where a patient presents for evaluation at the time of relicensure. Many of us have been confronted with individuals who lose visual acuity to or below 20/200 and are not due for relicensure. Some of these patients may not, in the ophthalmologist's view, be safe behind the wheel. Although the physician may recommend that the patient discontinue driving, there is no legal requirement for reporting visual loss as there is for certain communicable diseases, yet public safety may possibly be at risk. The medical-legal aspects of this situation also deserve scrutiny. Another question relates to visual field loss and deals with the same quandaries. However, there are some additional subtleties regarding loss of field: • Patients with acute homonymous hemianopias may be aware of the field defect for the first few weeks after onset of the loss. Driving could be hazardous for this group despite perimetry that may show the maintenance of 50° of nasal field and 70° temporally. Eventually, most patients lose consciousness of the defect, and by scanning or cerebral integration processes seem to function well. • Conversely, patients with gradual visual field loss due to glaucoma and parachiasmal tumors frequently are not at all aware of the deficit. In these diseases, the concentric constriction in field or a bitemporal hemianopsia would seem to present a hazard in driving, yet the very insidious progression of the loss likely accounts for the lack of patient consciousness of the deficit.
We thoroughly appreciate Dr. Frenkel's concern about the ignored responsibility of ophthalmologists. In New Jersey and many other states, there is no peripheral vision requirement, so that a person with 20/40 or better central vision with a 20° field can pass the visual requirement. I report such patients in a confidential communication to the Director of Motor Vehicles and ask if the patient has been involved in an accident or violation. Reference 4 of Dr. Lichter's editorial may give some comfort. These publications and letters show the need for ophthalmologists to become actively involved with the Department of Motor Vehicles. In some states, such as Pennsylvania, a physician enjoys immunity for reporting. A law or regulation that makes it mandatory to report all people who only have failed the visual requirement would be troublesome. However, it seems reasonable to enact a law requiring that a person be reported to the Director of Motor Vehicles if he has a physical or mental impairment which would make him an unsafe driver. GERALD FONDA, MD West Orange, New Jersey Dear Editor: I would like to share some comments and concerns regarding the recent article by Fonda and the related editorial regarding legal driving and low vision. In Fonda's article, the minimum distance needed to identify traffic signs was measured in eight subjects. However, only subjects 6 to 8 were visually impaired, according to the report. While all subjects had their vision blurred to 20/200, the remaining five subject presumably had no visually significant ocular pathology. Predictably, the five normal subjects were able to identify the traffic signs at shorter distances than the three subjects with ocular pathology, with the exception of one test sign. While the difference was not statistically significant (223 feet for blurred normals versus 252 feet for those with pathology, P = 0.081 ), the number of subjects tested was very small and the standard deviation in the observed measurements was very large. It is not valid to compare blurred normal subjects with low vision patients in such a study. Although the Snellen
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The following letters concern the lead article and editorial from the October 1989 issue of The Journal.
Fonda and Lichter have broached a subject which deserves further investigation as to the true functional abilities of patients with visual loss. The ophthalmologist's responsibility to these individuals and to the public at large requires definition. MARCEL FRENKEL, MD, MBA Chicago, Illinois
Fonda G. "Legal Blindness Can Be Compatible with Safe Driving" (Ophthalmology 1989; 96: 1457-9).
Author's reply
Lichter P. "The Ophthalmologist's Role in Licensing Drivers" (Ophthalmology 1989; 96:14556 [Editorial]).
Dear Editor:
Dear Editor: The article by Fonda and the accompanying editorial by Lichter highlight concerns which trouble the undersigned and likely many other practitioners. Fonda suggests that some patients with visual acuity less than 20/200 may drive safely given a minimum visual field of 120°. Several questions arise regarding the ophthalmologist's role in driving licensure. The above-referenced items discuss the situation where a patient presents for evaluation at the time of relicensure. Many of us have been confronted with individuals who lose visual acuity to or below 20/200 and are not due for relicensure. Some of these patients may not, in the ophthalmologist's view, be safe behind the wheel. Although the physician may recommend that the patient discontinue driving, there is no legal requirement for reporting visual loss as there is for certain communicable diseases, yet public safety may possibly be at risk. The medical-legal aspects of this situation also deserve scrutiny. Another question relates to visual field loss and deals with the same quandaries. However, there are some additional subtleties regarding loss of field: • Patients with acute homonymous hemianopias may be aware of the field defect for the first few weeks after onset of the loss. Driving could be hazardous for this group despite perimetry that may show the maintenance of 50° of nasal field and 70° temporally. Eventually, most patients lose consciousness of the defect, and by scanning or cerebral integration processes seem to function well. • Conversely, patients with gradual visual field loss due to glaucoma and parachiasmal tumors frequently are not at all aware of the deficit. In these diseases, the concentric constriction in field or a bitemporal hemianopsia would seem to present a hazard in driving, yet the very insidious progression of the loss likely accounts for the lack of patient consciousness of the deficit.
We thoroughly appreciate Dr. Frenkel's concern about the ignored responsibility of ophthalmologists. In New Jersey and many other states, there is no peripheral vision requirement, so that a person with 20/40 or better central vision with a 20° field can pass the visual requirement. I report such patients in a confidential communication to the Director of Motor Vehicles and ask if the patient has been involved in an accident or violation. Reference 4 of Dr. Lichter's editorial may give some comfort. These publications and letters show the need for ophthalmologists to become actively involved with the Department of Motor Vehicles. In some states, such as Pennsylvania, a physician enjoys immunity for reporting. A law or regulation that makes it mandatory to report all people who only have failed the visual requirement would be troublesome. However, it seems reasonable to enact a law requiring that a person be reported to the Director of Motor Vehicles if he has a physical or mental impairment which would make him an unsafe driver. GERALD FONDA, MD West Orange, New Jersey Dear Editor: I would like to share some comments and concerns regarding the recent article by Fonda and the related editorial regarding legal driving and low vision. In Fonda's article, the minimum distance needed to identify traffic signs was measured in eight subjects. However, only subjects 6 to 8 were visually impaired, according to the report. While all subjects had their vision blurred to 20/200, the remaining five subject presumably had no visually significant ocular pathology. Predictably, the five normal subjects were able to identify the traffic signs at shorter distances than the three subjects with ocular pathology, with the exception of one test sign. While the difference was not statistically significant (223 feet for blurred normals versus 252 feet for those with pathology, P = 0.081 ), the number of subjects tested was very small and the standard deviation in the observed measurements was very large. It is not valid to compare blurred normal subjects with low vision patients in such a study. Although the Snellen
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