Search

PURPOSE: To determine if incidence of contrast sensitivity (CS) impairment differs by generation and identify factors to explain these differences. METHODS: The Beaver Dam Eye Study (BDES) and Beaver Dam Offspring Study (BOSS) are cohort studies of aging adults in Beaver Dam, Wisconsin. Baseline examinations occurred from 1993–1995 (BDES) and 2005–2008 (BOSS). Follow-up examinations occurred in five-year intervals. CS testing was conducted with Pelli-Robson letter sensitivity charts; Incident impairment was a log CS score

Revised evidence-based entry criteria for visually-impaired shooting suggest that athletes with impaired contrast sensitivity (CS) and visual acuity (VA) worse than 0.6logMAR should be eligible for inclusion in the sport, rather than 1.0logMAR as previous. Is more than one class necessary for the sport with the revised minimum entry criterion? Twenty-five elite VI shooting athletes took part in the study. Two measures of visual function were assessed under standardised conditions: VA (using an ETDRS logMAR letter chart, and / or a BRVT chart) and CS (using both a Pelli-Robson chart and a Mars number chart). Shooting performance, in both prone and standing events, was measured during an international VI shooting competition. Fourteen of the 25 athletes had measurable VA, including 6 with VA better than 1.0logMAR. For CS, 8 athletes had measurable function with the Pelli-Robson chart and 13 with the Mars chart. The remaining athletes had function not numerically measurable by the charts and were considered to have no residual vision. There was no indication that shooting performance varied with visual function, and individuals with residual vision had no advantage over those without vision for either prone or standing shooting. The modifications made to the sport of VI shooting would appear to successfully render the sport of VI shooting equitable for all athletes with VA of less than or equal to 0.6 logMAR. Only one class is necessary for athletes once deemed as eligible to compete in VI shooting. An improved method of measuring CS in athletes with profound VI would be advantageous.

Objective: To examine rates of visual impairment of older adults in assisted living facilities (ALFs). Methods: Vision screening events were held at 12 ALFs in Jefferson County, Alabama, for residents above 60 years of age. Visual acuity, cognitive status, and presence of eye conditions were assessed. Results: A total of 144 residents were screened. Of these 67.8% failed distance screening, 70.9% failed near screening, and 89.3% failed contrast sensitivity screening. A total of 40.4% of residents had cognitive impairment and 89% had a least one diagnosed eye condition. Visual acuities did not differ significantly between cognitive status groups or with greater numbers of eye conditions. Discussion: This study is the first to provide information about vision impairment in the assisted living population. Of those screened, 70% had visual acuity worse than 20/40 for distance or near vision, and 90% had impaired contrast sensitivity. Cognitive impairment accounted for a small percentage of the variance in near vision and contrast sensitivity.

Purpose: The aim of this work was to evaluate the role of low vision aids in improving visual performance and response in children with low vision. Study Design: Prospective clinical case series. Materials and Methods: This study was conducted on 50 patients that met the international criteria for a diagnosis of low vision. Their ages ranged from 5 to 15 years. Assessment of low vision included distance and near visual acuity assessment, color vision and contrast sensitivity function. Low vision aids were prescribed based on initial evaluation and the patient's visual needs. Patients were followed up for 1 year using the tests done at the initial examination and a visual function assessment questionnaire. Results: The duration of visual impairment ranged from 1 to 10 years, with mean duration ± SD being 4.6± 2.3299. The near visual acuities ranged from A10 to A20, with mean near acuity ± SD being A13.632 ± 3.17171. Far visual acuities ranged from 6/60 (0.06) to 6/24 (0.25), with mean far visual acuity ± SD being 0.122 ± 0.1191. All patients had impaired contrast sensitivity function as tested using the vision contrast testing system (VCTS) chart for all spatial frequencies. Distance and near vision aids were prescribed according to the visual acuity and the visual needs of every patient. All patients in the age group 5-7 years could be integrated in mainstream schools. The remaining patients that were already integrated in schools demonstrated greater independency regarding reading books and copying from blackboards. Conclusion: Our study confirmed that low vision aids could play an effective role in minimizing the impact of low vision and improving the visual performance of children with low vision, leading to maximizing their social and educational integration.

Purpose To characterize visual function in type I diabetic patients prior to breakdown of the blood-retinal barrier or onset of vasculopathy as compared with patients with early diabetic retinopathy (DR). Methods Visual function was assessed by Multifocal Electroretinography (RetiScan - Roland Consult), Colour Vision (CCT - Cambridge Research Systems) and Frequency-Doubling Perimetry (FDT - Zeiss) in a population of 42 patients (age=26.6+5.3 years) divided into 2 groups: with no DR (n=26; VA=1.088+0.128) and with mild nonproliferative DR (n=16; VA=1.093+0.137). Fluorescein angiography was also performed in order to determine the absence or presence of initial vascular lesions. These data were compared with age-matched controls. Non-parametric statistical analysis was performed at a significance cut-off level of p

Article abstract People with AD have deficient contrast sensitivity and impaired face discrimination. The authors presented photographs of unfamiliar faces of three different sizes to enhance the low, middle, or high facial frequency information (cycles per face). Patients with AD demonstrated normal discrimination of small faces only, indicating that impaired contrast sensitivity at low facial frequencies contributes to their poor face discrimination.

We appreciate the effort Kooijman and Cornelissen have made to explain our finding that contrast sensitivity is an independent risk factor for multiple falls. In their letter, they propose an explanation why contrast sensitivity was related to multiple falls, whereas the ability to recognize small details was not. An intriguing question, because several studies have found associations between visual acuity and falling and others have found an association between contrast sensitivity and falling. We did not go into this in detail in our paper. On the basis of a paper Kooijman and Cornelissen wroteabout the relation between object detection and recognition and several aspects of vision, they concluded that object detection and recognition from a distance of 3 m was primarily related to contrast sensitivity and not so much to visual acuity. In addition, they reason that the decreased ability to detect and recognize objects might in turn lead to an increased chance of bumping into objects. In their final line of reasoning, they propose that the increased risk of bumping into obstacles increases the risk of falling. With this statement, however, they ignored the findings from several studies on the mechanisms of falling. These studies have shown that falling in visually impaired (or deprived) persons is most likely not so much caused by bumping into objects, but much more by disturbed postural stability and gait. In our paper, we addressed this mechanism by showing that physical performance and functional limitations could have mediated the relation between impaired contrast sensitivity and falling. Nonetheless, we agree with the recommendation of Kooijman and Cornelissen to improve contrast sensitivity by increasing the indoor and outdoor light levels. In the end, the exact mechanism by which visually impaired older men and women fall might not be so important as long as their primary impairment (decreased contrast sensitivity) can be counterbalanced. Finally, Kooijman and Cornelissen correctly noticed that we did not correct a typing error in the formula for calculating the integrated contrast sensitivity (ICS) in our paper. We did use the correct formula in the computation for the ICS in our analyses.

Transient covert attention increases contrast sensitivity at the target location with an informative spatial cue. Here we explored whether an uninformative spatial cue (50% valid with two possible locations) also increases contrast sensitivity and whether contrast sensitivity is altered at the uncued location as compared to the neutral condition. For all four observers, transient covert attention had both a benefit and a cost: it enhanced contrast sensitivity at the cued location and impaired contrast sensitivity at the uncued location at both parafoveal and peripheral positions. These results are consistent with the idea of limited resources, and indicate that transient attention helps control the expenditure of cortical computation.

A simple technique is described for assessing the sensitivity of the human visual system to gratings at threshold contrast. The technique has advantages for clinical use in that it is (1) inexpensive, (2) quick to administer, (3) portable, and (4) relatively free from bias. Forty-two diabetic patients and 84 normal controls have been tested. Fifteen diabetic patients (6/20 with retinopathy and 9/22 without) had test scores more than two standard deviations below the norm for age-matched controls.

Two separate reaction time studies concerning person recognition were conducted with ex-servicemen who incurred unilateral brain injury during the Second World War. The first experiment investigated the ability to construct a facial representation and involved deciding whether a stimulus represented a face or a “non-face” made by repositioning the facial features into an unnatural configuration. Men with posterior right hemisphere (RH) lesions performed this task more slowly than those with left hemisphere (LH) damage and control subjects; the latter two groups did not differ. The second experiment was designed to tap the most basic level of overt person recognition: awareness of familiarity. When faces were used as stimuli, the RH injured group again showed increased response latencies compared with the other two groups. The reverse pattern, slower reaction times for the men with LH lesions with no difference between RH injured and control subjects, emerged when written names were employed. Spatial contrast sensitivity functions were measured in both studies and although both LH and RH injured men showed impaired contrast sensitivity, no hemispheric difference was apparent. Instead, a double dissociation of impairments of contrast sensitivity and face processing was evident.