Aspects of vision loss – visual functions and functional vision

Integrated care in congenital glaucoma

“…The instrument of assessment was modelled after Colenbrander's visual ability scales [9] and consisted of an interview and an evaluation of performance in activities of daily living, communication, mobility, socio-emotional behaviour and participation, each main area divided in 5 secondary areas [9,10]. Performance levels were coded by means of a 10-point scale, in comparison with normal sighted children of the same age group: a point value of b6Q indicated adequate performance, over this value were the ranges of normal and near normal performance and under b6Q the ranges of restricted performance [9].…”

A VR-based user study on the effects of vision impairments on recognition distances of escape-route signs in buildings

“…According to the International Council of Ophthalmology [4], people with normal sight are able to recognize a visual angle of 1.25 angular minutes or less. Our weak blur represents a vision impairment corresponding to a minimum recognizable visual angle of 5.0 angular minutes, which is a reduction of the visual acuity by a factor of 4.…”

“…Even though our participants have corrected or normal sight, this resolution made it impossible for any of our participants to recognize a visual angle smaller than 2.5 angular minutes (∼ 0.4 logMAR). According to the International Council of Ophthalmology [4], visual acuity less or equal to 0.1 logMAR, corresponding to a maximum perceivable angle of 1.25 angular minutes, is considered normal vision. This means that just by putting on the VR headset, a person with normal sight will experience a loss of visual acuity that is already considered to be a mild vision impairment.…”

Characterising user capabilities to support inclusive design evaluation

“…Though ageing, disease and trauma account for this diversity, the characterisations of users based on levels of capability to perform actions in the world appear to be the most appropriate for product design and evaluation [9,21,52]. Figure 2 shows a useful framework for understanding the key relationship between low-level organ functions and high-level functional capabilities of the person as a whole [11]. The diagram highlights the links from disease to changes in function at the organ level, and the effects of these changes at the person level.…”

“…Adapted from [11] The set of maximum performance capacity measures form a performance envelope for an individual, not dissimilar to performance envelopes for other engineered systems such as cars and aircrafts. In essence, this method checks that the demands of the high-level task fall within a user's multidimensional performance capacity envelope, and then returns a negative result if a particular resource element is found to be a limiting factor.…”