Portable vision screener provides accurate clinical assessment for drivers, study finds

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A portable, comprehensive vision screener demonstrated strong agreement with standard clinical tests, according to a recent study published in Clinical Optometry. The study was conducted by researchers from Lotus College of Optometry and Lotus Eye Hospital in Mumbai, Maharashtra, India. The team, led by first author Mumtaz Qazi, MOptom, FIACLE, aimed to evaluate whether the portable screener would improve vision screening procedures for obtaining a drivers license and reduce the incidence of road traffic accidents (RTAs).

“There is a clear need for a time efficient, portable, and comprehensive vision screening solution that can reliably assess all key visual functions relevant to occupational driving, while remaining feasible for deployment in real-world screening environments,” the study authors stated.

Background

RTAs are a "significant public health concern in India,"¹ according to study authors. They are mainly caused by human error, which can be heavily attributed to visual functioning difficulties.^1-3 Driving requires an extensive array of visual abilities to ensure safety. Ideally, all drivers would receive a comprehensive eye exam, and follow up treatment to ensure all difficulties were addressed. However, due to cost and time constraints, this may not be feasible to provide for all drivers. Portable vision screeners (VS) provide a promising solution, capable of performing an array of visual assessments in approximately 7 ± 3 minutes (mean ± standard deviation).¹ The current study examined the efficacy of one screening device, Visiolite 4K, in detecting visual functioning difficulties and propose a more practical solution to address care gaps. The authors specifically examined measurements of distance visual acuity (DVA), stereopsis, color vision, contrast sensitivity, glare recovery, and peripheral visual field, as those are the most critical visual functions required for driving.

"A practical approach for driver licensing is to implement a two-step pathway in which all applicants first undergo a rapid, standardized vision screening, followed by a detailed confirmatory examination for those who fail or have borderline results," the study authors stated.¹

Study design and methods

The prospective cross-sectional study enrolled 384 licensed public transport drivers at community eye camps in Mumbai, with a mean age of 47.1 ± 9.14 years. Each participant underwent a full range of standard clinical assessments followed by the same tests performed using the Visiolite 4K vision screener (FIM Medical, France; distributed by Jutron Vision, India), a CE-certified class 1 medical device. Peripheral visual field results from the screener were separately validated against Tangent Screen testing in a subsample of 30 healthy individuals at a tertiary-care eye hospital, since Tangent Screen testing has specific lighting and spacial requirements.

Data assessment was conducted using SPSS version 31. Since the data was not normally distributed by Shapiro–Wilk testing, researchers used the Wilcoxon Signed-Rank Test to compare gold-standard and VS results. Receiver Operating Characteristic (ROC) curves were performed to determine sensitivity and specificity and Bland-Altman plots were used to assess agreement between gold standard and VS results.

Results

Distance visual acuity showed no statistically significant difference between the gold standard and the screener (0.22 ± 0.16 vs 0.20 ± 0.18 LogMAR; P>0.05). Stereopsis values also did not differ significantly (863.08 ± 1402.92 vs 656.54 ± 933.29 seconds of arc; P>0.05), though both methods showed high variability. Near visual acuity (0.46 ± 0.21 vs 0.38 ± 0.26 LogMAR), contrast sensitivity (2.98 ± 2% vs 5.7 ± 10.17%), and glare recovery (22.04 ± 6.39 vs 19.82 ± 6.22 seconds) all showed statistically significant differences between methods (P<0.05 for each).

For diagnostic accuracy, the screener showed 81% sensitivity and 91% specificity for distance visual acuity, and 58.5% sensitivity and 83.5% specificity for stereopsis. Color vision assessment showed low sensitivity (22.2%) but high specificity (89.2%) for detecting deficiency. In the 30-person peripheral field subsample, the screener showed 100% sensitivity and 100% specificity against Tangent Screen testing.

ROC analysis showed clinically significant diagnostic accuracy for distance visual acuity (AUC = 0.861; 95% CI, 0.788-0.933; P<0.001) and modest discriminative ability for stereopsis (AUC = 0.653; 95% CI, 0.589-0.718; P<0.001). Bland-Altman analysis showed satisfactory agreement across distance visual acuity, near visual acuity, contrast sensitivity, and stereopsis, with no evidence of systematic bias.

Mean testing time fell from 20 ± 5 minutes with the standard array of tests to 7 ± 3 minutes with the screener, a 65% reduction that the researchers noted could allow roughly 8 comprehensive screenings per hour, compared with about 3 per hour using gold-standard testing alone.

Findings and limitations

The researcher’s findings support the accuracy of results from Visiolite 4K screener based on recommended visual function metrics.⁴ Distance visual acuity remains the most significant visual skill for driving-related licensing decisions based on prior research.^1,3 The screener's sensitivity and specificity for that measure compared favorably with prior validation studies of other portable screeners. The screener's ability to assess peripheral visual field is a notable strength given its link to impaired hazard detection and situational awareness. Visiolite 4K allows eye care providers to review reports, which enables “teleoptometry or teleophthalmology support in locations where dedicated eye care professionals are not available,” as stated by the authors.¹

Based on their results, the researchers recommend a tiered, two-step screening approach for drivers, starting with a rapid VS screening. Patients with borderline or failing results to their initial vision assessment should pursue a detailed follow-up by an eye care provider.¹ Priority should be given to distance visual acuity measurements, followed by contrast sensitivity with glare testing and a peripheral awareness or visual field assessment.

The study's cross-sectional design did not allow evaluation of prospective crash outcomes. Reference testing was always performed before screener testing, which may have introduced learning or fatigue effects. Additionally, peripheral visual field assessment was only conducted on a small subset of participants (n=30). The study team emphasized that the vision screening is not intended for diagnostic purposes, and that follow-up care is needed for patients who receive failing or borderline results. They recommend future research to “evaluate the device’s performance when operated by trained non-specialists, as would typically occur in licensing centres and field-based settings.”¹

References

1. Qazi M, Chande PK, Jadhav ND, Khan N. Clinical validation of a comprehensive vision screener for assessing visual fitness for drivers in Mumbai, India. Clin Optom. 2026;18:622011. doi:10.2147/OPTO.S622011

2. Verma A, Chakrabarty N, Velmurugan S, Bhat P, Kumar D, Nishanthi B. Assessment of driver vision functions in relation to their crash involvement in India. Curr Sci. 2016;110(6):1063–1072. doi:10.18520/cs/v110/i6/1063-1072

3. Ekpenyong BN, Echendu D, Ekanem E. Visual health status and its relationship with road traffic accidents amongst Nigerian vehicle drivers. Afr Vision Eye Health. 2020;79(1):8. doi:10.4102/aveh.v79i1.577

4. Honavar SG. Should visual function tests be mandatory for a driving license? Ind J Ophthalmol. 2022;70(6):1871–1874. doi:10.4103/ijo. IJO_1273_22