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Journal Français d'Ophtalmologie
Volume 35, n° 4
pages 235-241 (avril 2012)
Doi : 10.1016/j.jfo.2011.06.007
Received : 11 May 2011 ;  accepted : 23 June 2011
Driving habits in glaucoma patients
Conduite automobile et glaucome
 

C. Parc , E. Tiberghien, V. Pierre-Kahn
Service d’ophtalmologie, hôpital Foch, 40, rue Worth, 92150 Suresnes, France 

Corresponding author.
Summary
Purpose

Glaucoma is a progressive optic neuropathy leading to loss of visual function beginning with the peripheral visual field. One large population-based study found that individuals with visual impairment reported difficulties in performing most vision-dependent daily activities, including difficulty with driving. The objective of this retrospective cohort study was to investigate the driving habits of glaucoma patients and to determine the conformance of their visual acuity and visual fields with driving regulations.

Methods

The charts of 20 patients followed in the Ophthalmology Department of Foch Hospital, Suresnes, Paris, France, with open angle glaucoma (mean visual field mean deviation of the worse eye: −15.5dB; range −1.97 to −27dB) and still driving, were reviewed. Data collected included visual acuity, type of glaucoma, slit lamp and fundus examination, most recent standard automated perimetry, and binocular visual field test results. Each patient was asked if he or she still drove on highways, and if he or she still drove at night.

Results

The driving habits of glaucoma patients were analyzed, and visual acuity and binocular visual fields were compared to French and European legal driving criteria. Thirteen patients (65%) with glaucoma were still driving on highways, and five (25%) at night. Seven patients (35%) were below French legal minimum visual acuity or visual field criteria.

Conclusion

Glaucoma patients appear to self-regulate their driving habits by avoiding potentially difficult driving situations. Further studies with larger sample size are necessary to determine relationships between severity of visual impairment, severity of visual field defects, and the cessation of driving.

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Résumé
But

Le glaucome est une neuropathie optique progressive, conduisant à la perte de la fonction visuelle, en commençant par le champ visuel périphérique. Une étude a montré que les gens présentant un déficit visuel signalaient des difficultés pour la conduite. L’objectif de cette étude rétrospective était d’évaluer les habitudes de patients glaucomateux, et d’étudier la conformité de leurs acuité et champ visuels avec la législation routière.

Méthodes

Les dossiers de 20 patients glaucomateux (moyenne des MD du pire œil : −15,5dB, allant de −1,97 à −27dB) conduisant, et suivis dans le service d’ophtalmologie de l’hôpital Foch à Suresnes, France, ont été analysés. L’acuité visuelle, le type de glaucome, la dernière périmétrie standard automatisée, et les champs visuels binoculaires ont été relevés. Il a été demandé à chaque patient s’il conduisait encore sur autoroute, et s’il conduisait toujours de nuit.

Résultat

Les habitudes de conduite ont été analysées. L’acuité visuelle et le champ visuel binoculaire ont été comparés aux normes françaises et européennes. Treize patients (65 %) conduisaient encore sur autoroute, et 5 (25 %) de nuit. Sept patients (35 %) étaient en dessous des minimums légaux d’acuité ou de champ visuel.

Conclusion

Les patients glaucomateux semblaient autoréguler leur mode de conduite en évitant les situations potentiellement difficiles. Une nouvelle étude sur une plus importante cohorte de patients serait intéressante pour rechercher s’il existe des corrélations statistiques entre la sévérité de la baisse d’acuité visuelle, l’atteinte des champs visuels et l’arrêt de la conduite automobile.

The full text of this article is available in PDF format.

Keywords : Driving habits, Esterman visual field test, Glaucoma, Driving ability, Vision

Mots clés : Conduite, Champ visuel Esterman, Glaucome, Aptitude à la conduite, Vision


Introduction

Glaucoma, one of the leading causes of blindness worldwide [1], is characterized by damage to the optic nerve [2], and can result in visual disability [3, 4]. The progression of the disease involves loss of mid-peripheral visual field in the early stages [5], followed in the later stages by loss of the central visual field [6].

Visual impairment (VI) is associated with limitations in mobility and activities of daily living. It can also have a major impact on people’s lives and force them into various alternative accommodations that limit their functioning and well being [7].

VI, in particular due to glaucoma, is associated with increased risk of falls and motor vehicle collisions [8, 9]. In a study concerning older drivers, it was found that subjects involved in injurious motor vehicle collisions (MVCs) were over three times more likely than those not involved in MVCs to have a confirmed diagnosis of glaucoma [10]. Other studies have found that patients with glaucoma are less likely to have been involved in MVCs [5]. In this study, we evaluated the driving habits of 20 glaucoma patients, and analyzed their suitability to drive motor vehicles, according to French1 and European legislation2 .

Methods

Charts of 20 patients with glaucoma who were know to drive were reviewed. Age, gender, and type of glaucoma were noted. Visual acuity was scored as the total number of lines read correctly in a decimal scale. The approximate equivalence in Snellen’s notation of metres and feet and in the decimal system is reported in Table 1.

The degree of VI was categorized in five mutually exclusive groups based on the presenting binocular visual acuity as follows: no VI (better than, but not including, 20/40 in each eye) (group I), unilateral mild VI (20/40-20/63 in one eye, no VI in the other eye) (group II), unilateral moderate/severe VI (20/80 or worse in one eye, no impairment in the other eye) (group III), bilateral mild VI (20/40-20/63 in one eye, 20/40 or worse in the other eye) (group IV), and bilateral moderate/severe VI (20/80 or worse in both eyes) (group V) [7]. Table 2 presents the groups with the visual acuity converted in the decimal notation. All patients had unilateral or bilateral glaucomatous optic disc damage, and a glaucomatous visual field defect detected by using standard automated perimetry (Humphrey field analyzer, Carl Zeiss Meditec, Inc, Dublin, CA). From perimetry, the worse eye was classified as having mild glaucoma (MD<−6dB), moderate glaucoma (MD<−12dB), or advanced glaucoma (MD>−12dB) [11]. Patients who had been included in the study had no systemic disease or medication known to affect visual acuity or visual fields. Only patients with mild cataract were included. Patients did not have any non-opthalmologic disorder that prevented them from driving. Self reported driving limitation on highways and cessation of night driving were noted. All patients had undergone a binocular Goldmann visual field examination (III-4-e target) and some patients also had a binocular Esterman test, using an American grid (Humphrey visual field analyser, Carl Zeiss Meditec, Dublin CA) [12, 13].

The visual acuity and Goldman binocular visual field data were compared to the French driving requirements1. The minimum required visual acuity is 5/10e, or 6/10e in the better eye if visual acuity of the other eye is below 1/10. The minimum horizontal binocular visual field is 120° and the minimum vertical binocular visual field is 60° (30° above and 30° below the visual axis). The European requirements2 are similar. The Esterman score was noted, and central binocular visual field defects within 20° of fixation were recorded.

Results

The charts of 20 patients were reviewed. Data are presented in Table 3. Fifteen patients were males and five were female. Mean age was 75 years (range: 45 to 89 years). All had primary open angle glaucoma, and glaucoma was bilateral in all cases.

Of the 20 patients, 11 (55%) had no VI, four (20%) and two (10%) had mild and moderate/severe unilateral VI respectively, and three (15%) had mild bilateral VI. None had moderate/severe bilateral VI. Three patients were classified as having mild glaucoma (MD<−6dB), three had moderate glaucoma (MD<−12dB), and 14 had advanced glaucoma (MD>−12dB). Thirteen patients (65%) were still driving on highways, whereas 15 patients (75%) had stopped driving at night. In one patient, visual acuity did not meet the criteria of French and European legislation to drive; this patient was classified as having advanced glaucoma, although their binocular visual field did meet legal criteria.

All patients in the study had performed a Goldman binocular visual field test, and 17 patients (85%) had also had an Esterman binocular visual field test (Figure 1). Six patients (30%) did not meet the legal requirements for the horizontal Goldman binocular visual field test. Three of these six patients were classified as having advanced glaucoma, one as having moderate glaucoma, and two as having mild glaucoma. No patient had a vertical binocular visual field less than 60°.



Figure 1


Figure 1. 

Esterman visual field test output from the Humphrey visual field analyser for one patient.

Zoom

The Esterman visual field scores ranged from 70 to 99. Nine (53%) Esterman visual fields showed central binocular visual field defects. Four of the nine patients with Esterman 20° central visual field defects did not meet the criteria of the French and European legislation to drive; one of these was failed to meet the visual acuity criteria, and the other three failed because of peripheral binocular visual field defects.

Discussion

Glaucoma is a progressive optic neuropathy that results in a characteristic deterioration of visual function. Early in the disease, this manifests as an impaired mid-peripheral visual field, which progressively increases toward the center. It is known that decreased visual acuity is associated with restricted ability to perform activities of daily living. NOE et al. found that patients with relatively minor binocular visual field loss have moderate to severe mobility restriction [2]. The authors found that reduced visual acuity may be a stronger determinant of a restricted ability to perform activities of daily living for individuals with glaucoma.

In the Los Angeles Latino Eye Study, greater severity of visual field loss in subjects with open angle glaucoma was associated with worse vision-related quality of life [14]. Another study found that glaucoma patients suffer from problems with outdoor mobility, glare and lighting, and household tasks [15]. Visual field loss was found to predispose subjects to both driving cessation and driving limitation [16] particularly due to glaucoma [17]. For McKean-Cowdin et al. [18], the self-reported health-related quality of life in a study of 5213 participants was diminished even in persons with relatively mild visual field loss on the basis of MD scores. The self-reported health-related quality of life related to difficulties with driving, distance and peripheral vision activities, and dependency. Patients with glaucoma perceive more difficulty driving than individuals without glaucoma [19]. Driving limitation or cessation because of glaucoma decreases independence of daily living, and can result in social isolation [17].

In our study, among the five patients who still drove at night, three were in group I, one was in group II, and one was in group III of the VI classification. Among the 13 patients who still drove on highways, six were in group I, three in group II, two in group III, and two were in group IV.

Varma et al. found in a cohort of 7789 participants that VI begins to impact health-related quality of life (HRQOL) at the unilateral moderate/severe or bilateral mild severity levels [7]. At those severity levels, individuals reported greater difficulty performing most vision-dependent daily activities such as driving.

For Szlyk et al. [8], visual field sensitivity measured within 24° of fixation was not related to changes in driving performance, and neither were the measures of far peripheral vision in their group of glaucoma patients. For this reason, these authors performed Esterman visual field tests that provided a more sensitive screening measure for peripheral visual field loss. In the same study, the increased incidence of accidents of the glaucoma group indicated that the glaucoma subjects were not able to compensate for their visual field loss during driving [8]. In the United Kingdom, Ang et al. found that a significant proportion of patients with primary open angle glaucoma do lose vision resulting in driving ineligibility and certification as visually impaired, although actual blindness from glaucoma was uncommon [20].

In another study [21], patients with 100° or less of binocular visual field (III-4-e Goldman target) had more accidents than patients with a binocular visual field greater than 100°.

For Owsley et al. [10], elderly drivers with substantial useful field of vision reduction were at least 20-times more likely to be involved in an injurious crash than were those with no or minor reductions. This study identified glaucoma as an independent risk factor for injurious crash occurrence by older drivers.

However, for Kotecha et al. [22], it appears unlikely that simple cut-offs based on visual acuity and visual field are enough to predict driver safety. In that study, the authors found that drivers with perceived VI would limit their exposure to driving.

Other studies found that patients with glaucoma were less likely to have been involved in MVCs [5]. In this study, it appears to the authors that drivers with glaucoma self-regulate their driving habits by avoiding potentially difficult driving situations.

In our study, binocular visual fields were performed, because they measure the functional field and then constitute a realistic assessment of total peripheral function [12]. They have no value in glaucoma diagnosis. The Esterman binocular visual field is a method that outlines the total visual field binocularly in a way that it is used in nature. It scores functionally, giving greater weight to the more important areas [12]. The test uses a grid of 120 test points to examine more than 130° of visual field. Each location is tested once with a size III white stimulus with an intensity of 10dB. Missed points are retested, and two negative responses are recorded as a defect. Stability of fixation is monitored indirectly by observation [6]. The Esterman score is calculated by dividing the number of correct responses by the total number of stimuli (120) and multiplying by 100. Fujita et al. found that the Esterman score was a good predictor of difficulty with daily living. They found a low Esterman score, around 40, when the patients described difficulties in daily living [23]. In our study, no patient had a low Esterman score, and yet many patients in our study had spontaneously limited their driving habits.

NOE et al. [2] inundated that the Esterman test might not be the best test to measure visual field loss for association with quality of life because they did not find a correlation between the Esterman binocular visual field test score and quality of life. The Esterman visual field test provides a quick and easy way of determining central binocular visual field defects. However, it has been shown to have limitations, mainly the poor breadth of measurement over the range of visual field loss, and the testing pattern may miss central defects [3]. In our study, the Esterman score was always above 70, and in Harris et al. study [13], the Esterman score was always above 50, including the most severely affected patients. Such a finding can be explained by the phenomenon of binocular summation. The Esterman test had been originally devised to determine how useful the patient’s visual field was, and not specifically developed as a test for driving.

In our study, 13 patients (65%) fulfilled French legal requirements established in 2005 and European requirements established in 2009. Seven patients did not meet those legal requirements; one patient had too low visual acuity (group IV of VI) and six patients had a binocular horizontal visual field less than 120°. The patient with poor visual acuity met the horizontal binocular visual field criteria, and the patients with an impaired binocular visual field met the visual acuity criteria. These patients had been classified in group I of VI. The patients with too low binocular visual fields had Esterman scores ranging from 70 to 90, and only three had central defects.

The regulations on driving vary from country to country, and seem more severe in some other countries. This is particularly true in the UK where the recommended definition of the standard of the minimum field of vision for safe driving includes, “no significant field defect in the binocular field which encroaches within 20° of fixation either above or below the horizontal meridian” [24]. In our study, 13 patients would have been below the minimum field of vision for safe driving in the UK.

Conclusion

This study shows that 75% of glaucoma patients drastically restrict their exposure to driving. They self-restricted their driving habits because of perceived difficulties, in particularly driving on highways and at night, thus avoiding difficult driving situations. Most of the patients met the minimum legal requirements for driving. Thirty percent of those patients did not meet the French and European legal requirements for driving. They belong to different glaucoma MD severity groups, different VI severity groups, and few of them had central Esterman defects. Further studies with more patients are necessary to assess correlations between those three parameters, the driving habits, and the driving requirements.

Disclosure of interest

The authors declare that they have no conflicts of interest concerning this article.


Acknowledgment

The authors acknowledge the assistance of perimetrist Willy Fortas Pontalay, and of Sanjay V. Patel, M.D.

References

Quigley H.A. Number of people with glaucoma worldwide Br J Ophthalmol 2000 ;  80 : 389-393
Noe G., Ferraro J., Lamoureux E., Franzco J.R., Keeffe J.E. Associations between glaucomatous visual field loss and participation in activities of daily living Clin Exp Ophthalmol 2003 ;  31 : 482-486 [cross-ref]
Owen V.M., Crabb D., White E., Viswanathan A., Garway-Heath D., Hitchings R. Glaucoma and fitness to drive: using binocular visual fields to predict a milestone to blindness Invest Ophthalmol Vis Sci 2008 ;  49 : 2449-2455 [cross-ref]
Ramulu P. Glaucoma and disability: which tasks are affected, and at what stage of disease? Curr Opin Ophthalmol 2009 ;  20 : 92-98 [cross-ref]
McGwin G., May A., Joiner W., DeCarlo D.K., McNeal S., Owsley C. Is glaucoma associated with motor vehicle collision involvement and driving avoidance? Invest Ophthalmol Vis Sci 2004 ;  45 : 3934-3939 [cross-ref]
Jampel H.D. Glaucoma patients assessment of their visual function and quality of life Trans Am Ophthalmol Soc 2001 ;  99 : 301-317
Varma R., Wu J., Chong K., Azen S.P., Hays R. Impact of severity and bilaterality of visual impairment on health-related quality of life Ophthalmology 2006 ;  113 : 1846-1853 [cross-ref]
Szlyk J.P., Mahler C.L., Seiple W., Edward D.P., Wilensky J.T. Driving performance of glaucoma patients correlates with peripheral visual field loss J Glaucoma 2005 ;  14 : 145-150 [cross-ref]
Ivers R.Q., Cumming R.G., Mitchell P., Attebo K. Visual impairment and falls in older adults: the Blue Mountains Eye Study J Am Geriatr Soc 1998 ;  46 : 58-64
Owsley C., McGwin G., Ball K. Vision impairment, eye disease, and injurious motor vehicle crashes in the elderly Ophthalmic Epidemiol 1998 ;  5 : 101-113 [cross-ref]
Brusini P., Filacorda S. Enhanced Glaucoma Staging System (GSS 2) for classifying functional damage in glaucoma J Glaucoma 2006 ;  15 : 40-46 [cross-ref]
Esterman B. Functional scoring of the binocular field Ophthalmology 1982 ;  89 : 1226-1234
Harris ML, Jacobs NA. Is the Esterman binocular field sensitive enough? Perimetry Update 1994/95:403–4.
McKean-Cowdin R., Wang Y., Azen S.P., Varma R.Los Angeles Latino Eye Study Group Impact of visual field loss on health-related quality of life in glaucoma: the Los Angeles Latino Eye Study Ophthalmology 2008 ;  115 : 941-948
Nelson P., Aspinall P., O’Brien C. Patients’ perception of visual impairment in glaucoma: a pilot study Br J Ophthalmol 1999 ;  83 : 546-552 [cross-ref]
Freeman E.E., Munoz B., Turano K.A., West S.K. Measures of visual function and their association with driving modification in older adults Invest Ophthalmol Vis Sci 2006 ;  47 : 514-520 [cross-ref]
Ramulu P.Y., West S.K., Munoz B., Jampel H.D., Friedman D.S. Driving cessation and driving limitation in glaucoma: the Salisbury Eye Evaluation Project Ophthalmology 2009 ;  116 : 1846-1853 [cross-ref]
McKean-Cowdin R., Varma R., Wu J., Hays R.D., Azen S.P. Los Angeles Latino Eye Study Group. Severity of visual field loss health-related quality of life Am J Ophthalmol 2007 ;  143 : 1013-1023 [inter-ref]
Gutierrez P., Wilson M.R., Johnson C., Gordon M., Cioffi G.A., Ritch R., and al. Influence of glaucomatous visual field loss on health-related quality of life Arch Ophthalmol 1997 ;  115 : 777-784
Ang G.S., Eke T. Lifetime visual prognosis for patients with primary open-angle glaucoma Eye 2007 ;  21 : 604-608
Szlyk J.P., Alexander K.R., Severing K., Fishman G.A. Assessment of driving performance in patients with retinitis pigmentosa Arch Ophthalmol 1992 ;  110 : 1709-1713
Kotecha A., Spratt A., Viswanathan A. Visual function and fitness to drive Br Med Bull 2008 ;  87 : 163-174 [cross-ref]
Fujita K., Yasuda N., Nakamoto K., Fukuta T. The relationship between difficulty in daily living and binocular visual field in patients with glaucoma Nippon Ganka Gakkai Zasshi 2008 ;  112 : 447-450
Taylor J.F. Medical aspects of fitness to drive. A guide for medical practitioners  London: HMSO (1995). p. 119–21.

1  Ordinance of December 21, 2005, Legal Code of the Republic of France, establishing the list of medical conditions incompatible with obtaining or maintaining a driver’s license, or requiring a limited-term driver’s license. Visual impairments.
2  Directive 2009/113/EC of the August 25, 2009 Commission amending Directive 2006/126/EC of the European Parliament and the Council on driver’s licenses.


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