Keziah Latham

Important areas of the central binocular visual field for daily functioning in the visually impaired.

Citation information: Tabrett DR & Latham K. Important areas of the central binocular visual field for daily functioning in the visually impaired. Ophthalmic Physiol Opt 2012, 32, 156–163. doi: 10.1111/j.1475‐1313.2012.00892.x

Spatial localisation in autism: evidence for differences in early cortical visual processing

BackgroundVision in people with autism spectrum conditions (ASC) is reported to be different from people without ASC, but the neural level at which the differences begin to occur is not yet known. Here we examine two variants of a vernier acuity task to determine if differences are evident in early visual processing.FindingsAbutting and separated vernier acuity was assessed in 16 people with ASC and 14 matched controls. In controls, abutting and separated thresholds were unrelated (r = 0.13, p = 0.65), suggesting thresholds are determined by two separate mechanisms. In contrast, the abutting and separated thresholds of ASC observers were strongly correlated (r = 0.88, p < 0.0001), with separated thresholds tending towards being superior to those of controls [t(28) = −2.46, p = 0.02].ConclusionsThe findings suggest the mechanisms employed by ASC observers in separated vernier tasks are different to those of controls. This psychophysical evidence suggests that visual differences in ASC may begin at an early cortical stage of visual processing.

Assessing visual activities of daily living in the visually impaired.

Purpose:  Visual function assessment questionnaires ask people to rate the difficulty they have performing visual activities of daily living (ADLs). This study examines the relationship between self‐reported difficulty and actual performance in such ADLs.

Guidelines for predicting performance with low vision AIDS.

Purpose. To determine predictors of success in reading with low vision aids, in terms of reading acuity, optimum acuity reserve, and maximum reading speed, for observers with vision loss from various causes. Methods. One hundred people with vision loss affecting their daily lives participated. Clinical visual function measurements of distance acuity, contrast sensitivity, binocular threshold visual fields, and near reading performance with a MNRead chart at 40 cm were obtained. Reading performance aided by habitual low vision aids was also assessed with a MNRead chart. Results. Aided reading acuity was best predicted by clinical reading acuity and contrast sensitivity. For most observers, a 2:1 acuity reserve was sufficient to achieve near-maximum reading speed, but one-third of observers with aided reading acuity better than 1.2M required a higher acuity reserve. Aided maximum reading speed was best predicted by clinically assessed reading speed and by clinical reading acuity. Conclusions. People with vision impairment are likely to achieve 1M with a low vision aid if their clinically assessed reading acuity is better than 0.85 logMAR. If acuity is worse than this, but contrast sensitivity is better than 1.05 logCS, 1M is also likely to be achieved. A 2:1 acuity reserve is adequate for 75% of observers, but those with good aided reading acuity may require further magnification to achieve best reading speeds. Fluent reading (>80 words per minute) is likely to be achieved if an observer reads fluently with large print at a fixed working distance and if clinically assessed reading acuity is better than 1.0 logMAR.

A randomised clinical trial to assess the effect of a dual treatment on myopia progression: The Cambridge Anti‐Myopia Study

To evaluate the effect of a dual treatment modality for myopia, by improving accommodative functions, on myopia progression.

Adjustment to vision loss in a mixed sample of adults with established visual impairment.

PURPOSE To determine factors associated with the level of adjustment to vision loss in a cross-sectional sample of adults with mixed visual impairment. METHODS One hundred participants were administered the Acceptance and Self-Worth Adjustment Scale (AS-WAS) to assess adjustment to vision loss. The severity of vision loss was determined using binocular clinical visual function assessments including visual acuity, contrast sensitivity, reading performance, and visual fields. Key demographics including age, duration of visual impairment, general health, education, and living arrangements were evaluated, as were self-reported vision-related activity limitation (VRAL), depression, social support, and personality. RESULTS Multivariate analysis showed that higher levels of depressive symptoms (β = -0.26, P < 0.01) and of the personality trait neuroticism (β = -0.33, P < 0.001), and lower levels of the personality trait of conscientiousness (β = 0.29, P < 0.01), were associated with poorer adjustment to vision loss, explaining 56% variance. CONCLUSIONS Adjustment to vision loss is significantly associated with depression and certain traits of personality (specifically neuroticism and conscientiousness), independent of the severity of vision loss, VRAL, and duration of vision loss. The results suggest certain individuals may be predisposed to exhibiting less adjustment to vision loss due to personality characteristics, and exhibit poorer adjustment owing to or as a consequence of depression, rather than due to other factors such as the onset and severity of visual impairment.

Do best practice guidelines improve the legibility of pharmacy labels for the visually impaired

Citation information: Latham K, Waller S & Schaitel J. Do best practice guidelines improve the legibility of pharmacy labels for the visually impaired? Ophthalmic Physiol Opt 2011, 31, 275–282. doi: 10.1111/j.1475‐1313.2010.00816.x

The relationship between visual function and performance in rifle shooting for athletes with vision impairment

Background Paralympic sports provide opportunities for those who have an impairment that might otherwise be a barrier to participation in regular sporting competition. Rifle shooting represents an ideal sport for persons with vision impairment (VI) because the direction of the rifle can be guided by auditory information when vision is impaired. However, it is unknown whether those with some remaining vision when shooting with auditory guidance would be at an advantage when compared with those with no vision at all. If this were the case then it would be necessary for those with and without remaining vision to compete in separate classes of competition. Materials and method The associations between shooting performance and 3 measures of visual function thought important for shooting were assessed for 10 elite VI shooters currently classified as VI. A conventional audiogram was also obtained. Results The sample size, though small, included the majority of European VI shooters competing at this level. The relationships between visual functions and performance confirmed that individuals with residual vision had no advantage over those without vision when auditory guidance was available. Auditory function was within normal limits for age, and showed no relationship with performance. Summary The findings suggest that rifle-shooting athletes with VI are able to use auditory information to overcome their impairment and optimise performance. Paralympic competition should be structured in a way that ensures that all shooters who qualify to compete in VI shooting participate within the same class irrespective of their level of VI.

Difficulties With Goals of the Dutch ICF Activity Inventory: Perceptions of Those With Retinitis Pigmentosa and of Those Who Support Them

PURPOSE To provide a comprehensive overview of the perceived difficulties with visual activities and participation by those with retinitis pigmentosa (RP), and as perceived by those who support people with RP. Further, to examine the performance of the Dutch ICF Activity Inventory (D-AI) using Rasch analysis. METHODS Three hundred fifty people with RP and 75 supporters of people with RP provided demographic information and completed the D-AI at goal level (47 goals). RESULTS Following removal of four goals, the D-AI behaved well in Rasch analysis, but with limitations to its unidimensionality. The most difficult goals for people with RP related to mobility and to work-related activities. Greater difficulty was associated with higher visual impairment registration status, use of mobility aids, and longer duration of visual impairment. For those with less severe visual loss, goals relating to communicating with people were relatively more difficult. In more severe loss, goals involving good central vision (e.g., dealing with correspondence) were relatively more difficult. The perceptions of supporters matched those of the people with RP relatively well, but with a tendency for supporters to overestimate the difficulty of goals, which related to administration and domestic chores, and to underestimate difficulty with goals relating to communication with people. CONCLUSIONS The results indicate important areas of rehabilitation to address in addition to orientation and mobility in those with RP, including work-related activities and goals involving good central vision. Both people with RP and those supporting them could benefit from help addressing difficulties with communication.

Evaluation of an Emotional Support Service for the Visually Impaired

Purpose To evaluate the impact of a facilitated peer group emotional support service on visual quality of life (VQoL). Methods Consecutive participants in an emotional support service delivered to groups of up to six and facilitated by trained counselors were recruited (n = 29). The VCM1 (Vision Quality-of-life Core Measure) instrument was administered to participants at the start of the service, at the end of the service, and 6 months after completion of the service. Results For the group as a whole, VQoL significantly improved between the beginning of the service and the end (F1,23 = 16.43, p = 0.000) but was no better than at the start 6 months later (F1,23 = 3.60, p = 0.07). However, those with poorer initial VQoL showed significantly greater improvements after 6 months (1.74 ± 2.21 logits) than those with higher initial VQoL (−0.12 ± 0.71 logits) (t23 = 2.89, p = 0.008). The effect size of the intervention for those with poor initial VQoL was 1.10 at the end of service and 0.92 after 6 months. The items that became and remained easier were “feeling lonely or isolated due to eyesight,” “feeling sad or low due to eyesight,” and “feeling worried about general safety outside the home.” Conclusions This facilitated peer group emotional support service significantly improves VQoL as assessed with the VCM1 over at least 6 months for those with poorer initial VQoL. Different interventions may be needed for those with initially good VQoL and to improve other aspects of QoL not influenced by the service.