Abnormal Visual Function: An Under-recognized Risk Factor of Road Traffic Injuries


Purpose: To determine the relationship between road accidents with visual acuity, refractive errors, visual field, and contrast sensitivity.

Methods: This population-based case–control study was conducted on roads leading to Tehran Province, Iran. The case group comprised drivers who had met with accidents and were at fault for the accident. The cases were selected in an ongoing manner (incidence cases). The controls were drivers who were the opposing victims in the same. After an initial interview, optometric and ophthalmic examinations including the measurement of visual acuity, refraction, visual field assessment, contrast sensitivity measurement, and slit lamp biomicroscopy were performed for all study participants.

Results: In this study, 281 and 204 individuals were selected for the case and control groups. The mean uncorrected visual acuity was 0.05 ± 0.12 and 0.037 ± 0.10 logMAR in the case and control groups, respectively (P = 0.095). Of the participants in the case and control groups, 32.8% and 23% had a visual field defect in at least one eye, respectively (adjusted odds ratios [aOR] = 1.63, 95% confidence interval [CI]: 1.08–2.48; P = 0.021). Moreover, 16.2% of the cases and 8.3% of the controls had visual field defects in both eyes (aOR = 2.13, 95% CI: 1.17–3.86; P = 0.012). Contrast sensitivity was worse in the case group in all spatial frequencies under non-glare conditions. However, under glare conditions, the contrast sensitivity was significantly worse in the case group only in the spatial frequency of 12 cycles per degree (cpd).

Conclusion: Reduced contrast sensitivity, especially under non-glare conditions, and visual field defects are risk factors that influence the prevalence of road accidents. It is strongly advised that special attention be paid to these visual functions in legal assessments to apply the necessary interventions in individuals with these types of disorders.


Case–Control Study, Contrast Sensitivity, Road Traffic Injury, Visual Field

1. World Health Organization (WHO). Global status report on road safety 2018: Summary. World Health Organization; 2018.

2. Urie Y, Velaga NR, Maji A. Cross-sectional study of road accidents and related law enforcement efficiency for 10 countries: A gap coherence analysis. Traffic Inj Prev 2016;17:686–691.

3. Saadat S, Yousefifard M, Asady H, Moghadas Jafari A, Fayaz M, Hosseini M. The most important causes of death in Iranian population; a retrospective cohort study. Emergency 2015;3:16–21.

4. Shahbazi F, Soori H, Khodakarim S, Ghadirzadeh, M, Hashemi-Nazari SS, et al. Analysis of mortality rate of road traffic accidents and its trend in 11 years in Iran. Arch Trauma Res 2019;8:11–16.

5. Bahadorimonfared A, Soori H, Mehrabi Y, Delpisheh A, Esmaili A, Salehi M, et al. Trends of fatal road traffic injuries in Iran (2004-2011). PLoS One 2013;8:e65198.

6. Oladehinde MK, Adeoye AO, Adegbehingbe BO, Onakoya AO. Visual functions of commercial drivers in relation to road accidents in Nigeria. Indian J Occup Environ Med 2007;11:71–75.

7. Wood JM. Aging, driving and vision. Clin Exp Optom 2002;85:214–220.

8. Owsley C, McGwin G Jr. Vision and driving. Vision Res 2010;50:2348–2361.

9. Keeffe JE, Jin CF, Weih LM, McCarty CA, Taylor HR. Vision impairment and older drivers: Who’s driving? Br J Ophthalmol 2002;86:1118–1121.

10. Gresset JA, Meyer FM. Risk of accidents among elderly car drivers with visual acuity equal to 6/12 or 6/15 and lack of binocular vision. Ophthalmic Physiol Opt 1994;14:33–37.

11. Rubin GS, Ng ES, Bandeen-Roche K, Keyl PM, Freeman EE, West SK. A prospective, population-based study of the role of visual impairment in motor vehicle crashes among older drivers: the SEE study. Invest Ophthalmol Vis Sci 2007;48:1483–1491.

12. Marottoli RA, Richardson ED, Stowe MH, Miller EG, Brass LM, Cooney LM Jr, et al. Development of a test battery to identify older drivers at risk for self-reported adverse driving events. J Am Geriatr Soc 1998;46:562–568.

13. Cross JM, McGwin G Jr, Rubin GS, Ball KK, West SK, Roenker DL, et al. Visual and medical risk factors for motor vehicle collision involvement among older drivers. Br J Ophthalmol 2009;93:400–404.

14. Owsley C, Stalvey BT, Wells J, Sloane ME, McGwin G Jr. Visual risk factors for crash involvement in older drivers with cataract. Arch Ophthalmol 2001;119:881–887.

15. Mäntyjärvi M, Juntunen V, Tuppurainen K. Visual functions of drivers involved in traffic accidents. Accid Anal Prev 1999;31:121–124.

16. Cole BL. Protan colour vision deficiency and road accidents. Clin Exp Optom 2002;85:246–253.

17. Racette L, Casson EJ. The impact of visual field loss on driving performance: Evidence from on-road driving assessments. Optom Vis Sci 2005;82:668–674.

18. Adekoya BJ, Owoeye JF, Adepoju FG, Ajaiyeoba AI. Visual function survey of commercial intercity vehicle drivers in Ilorin, Nigeria. Can J Ophthalmol 2009;44:261–264.

19. Usrey WM, Reid RC. Synchronous activity in the visual system. Annu Rev Physiol 1999;61:435–456.

20. Onabolu OO, Bodunde OT, Otulana TO, Ajibode HA, Awodein OG, Onadipe OJ, et al. Visual acuity of commercial motor drivers in Ogun State of Nigeria. Niger Postgrad Med J 2012;19:225–229.

21. Hashemi H, Yekta A, Jafarzadehpur E, Doostdar A, Ostadimoghaddam H, Khabazkhoob M. The prevalence of visual impairment and blindness in underserved rural areas: A crucial issue for future. Eye 2017;31:1221–1228.

22. Shahriari HA, Izadi S, Rouhani MR, Ghasemzadeh F, Maleki AR. Prevalence and causes of visual impairment and blindness in Sistan-va-Baluchestan Province, Iran: Zahedan Eye Study. Br J Ophthalmol 2007;91:579–584.

23. Owsley C, McGwin G Jr. Vision impairment and driving. Surv Ophthalmol 1999;43:535–550.

24. Decina LE, Staplin L. Retrospective evaluation of alternative vision screening criteria for older and younger drivers. Accid Anal Prev 1993;25:267–275.

25. McCloskey LW, Koepsell TD, Wolf ME, Buchner DM. Motor vehicle collision injuries and sensory impairments of older drivers. Age Ageing 1994;23:267–273.

26. Freeman EE, Muñoz B, Turano KA, West SK. Measures of visual function and their association with driving modification in older adults. Invest Ophthalmol Vis Sci 2006;47:514–520.

27. Lyman JM, McGwin G Jr, Sims RV. Factors related to driving difficulty and habits in older drivers. Accid Anal Prev 2001;33:413–421.

28. Danielson RW. The relationship of fields of vision to safety in driving; with a report of 680 drivers examined by various screening methods. Am J Ophthalmol 1957;44:657–680.

29. Johnson CA, Keltner JL. Incidence of visual field loss in 20,000 eyes and its relationship to driving performance. Arch Ophthalmol 1983;101:371–375.

30. Haymes SA, Leblanc RP, Nicolela MT, Chiasson LA, Chauhan BC. Risk of falls and motor vehicle collisions in glaucoma. Invest Ophthalmol Vis Sci 2007;48:1149–1155.

31. Huisingh C, McGwin G Jr, Wood J, Owsley C. The driving visual field and a history of motor vehicle collision involvement in older drivers: A population-based examination. Invest Ophthalmol Vis Sci 2014;56:132–138.