Jones et al. have evaluated the use of a binocular head mounted video display to simulate everyday difficulties caused by advanced glaucomatous visual impairment (VI). Individuals with glaucoma often report particular difficulty in locating objects in cluttered visual scenes, and also exhibit reduced mobility.1 The authors measured the time required for normally sighted adults to complete search and mobility tasks while wearing video goggles that simulate advanced glaucomatous visual field loss (VFL) in the superior field and, separately, the same VFL in the inferior field. Simulated scotoma position was constantly tracked to gaze direction, and eye and head movements were used to assess individual differences in looking behaviors.
The location of VFL can be nearly as important as the presence of the loss itself
The authors found that their simulations of VFL substantially impaired visual search capability and mobility, especially when the simulated VFL was in the inferior field, thus confirming qualitative comparisons of inferior versus superior VFL from glaucoma patients.2 The authors also found that the difference in search time between inferior and superior VFL was 70% of the search time difference between superior VFL and normal vision, suggesting that the location of VFL can be nearly as important as the presence of the loss itself. Similarly, inferior field loss affected mobility more than superior loss. The authors also found considerable inter-individual variability in how well subjects coped with simulated VFL and that these differences were associated with systematic differences in gaze behavior.
Scotoma simulation and quantification of VI effects in terms of task completion times are not new ideas,3 and the most important new message in this paper may be that such measurements now can be done using widely available hardware, combined with software that the authors have made freely available online. Thus, others now can efficiently confirm the authors' findings and then move forward with their own refinements and innovations.
We wonder ‐ as do the authors ‐ if their device might be used to quantify VI effects on other tasks, e.g., tasks that map onto each of the categories of behavior defined in the National Eye Institute's visual function questionnaire (NEI-VFQ-25).4 Such simulations might also help architects design buildings that are more accessible to individuals with vision impairment. A widely-available simulator might lead to refinement and standardization of criteria for visual disability. It also might contribute to the development of improved coping strategies for those who have such impairments, or to assessment of the relative benefits of alternative treatment options for blinding eye disease.
Such measurements now can be done using widely available hardware, combined with software that the authors have made freely available online
This paper has expanded my own views regarding the opportunity for further development, and perhaps even standardization of visual impairment assessments. I thank the authors for this important contribution.