PURPOSE:. To determine the effects of blurring vision on whole-body center-of-mass (CM) dynamics and foot-clearance parameters in elderly individuals performing a single step up to a new level. METHODS:. Twelve healthy subjects (mean age, 72.3 +/-4.17 years) performed a single step up to a new level (heights of 73 and 146 mm). Trials were undertaken with vision optimally corrected and with vision diffusively blurred by light-scattering lenses (cataract simulation). CM and foot-clearance parameter data were assessed by analyzing data collected by a five-camera, three-dimensional (3-D) motion analysis system. RESULTS:. When vision was blurred, subjects took 11% longer to execute the stepping task (P < 0.05), mediolateral displacement of the point of application of the ground reaction force vector (i.e., weighted average of all pressures over the area in contact with the ground; the so called center of pressure, CP) decreased from 37.6% of stance width to 28.3% (P < 0.01), maximum distance between the mediolateral position of the CM and CP decreased by 9.8 mm (P < 0.01), and toe clearance (distance between tip of shoe and edge of step) increased in both the horizontal (28%) and vertical (19%) direction (P < 0.05). CONCLUSIONS:. These findings suggest that when vision was blurred, subjects used a twofold safety-driven adaptation: First, to increase dynamic stability they ensured that the horizontal position of their CM was kept close to the center of the base of support and second, they increased horizontal and vertical toe clearance while swinging their lead limb forward to reduce the risk of tripping.

Yes / This article reviews the literature on how blurred vision contributes to falls, gait, and postural control and discusses how these are influenced by spectacle correction. Falls are common and represent a very serious health risk for older people. They are not random events as studies have shown that falls are linked to a range of intrinsic and extrinsic risk factors. Vision provides a significant input to postural control in addition to providing information about the size and position of hazards and obstacles in the travel pathway and allows us to safely negotiate steps and stairs. Many studies have shown that reduced vision is a significant risk factor for falls. However, randomized controlled trials of optometric interventions and cataract surgery have not shown the expected reduction in falls rate, which may be due to magnification changes (and thus vestibuloocular reflex gain) in those participants who have large changes in refractive correction. Epidemiological studies have also shown that progressive addition lens and bifocal wearers are twice as likely to fall as non-multifocal wearers, laboratorybased studies have shown safer adaptive gait with single-vision glasses than progressive addition lenses or bifocals, and a randomized controlled trial has shown that an additional pair of distance vision single-vision glasses for outdoor use can reduce falls rate. Clinical recommendations to help optometrists prevent their frail, older patients from falling are suggested. / Grant support: Atkinson Charitable Foundation, College of Optometrists, Dunhill Medical Trust, Essilor International R&D, Federation of Ophthalmic & Dispensing Opticians, Health & Welfare Canada, Health Foundation, National Institute for Health Research, PPP Foundation, and Vicon Motion Systems Ltd.

Thesis (MPH.) -- University of Limpopo, 2021 / Dry eye disease (DED) is defined as a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolality of the tear film and inflammation of the ocular surface. DED is one of the most frequently established diagnoses in ophthalmology and represents a growing public health concern, with consequences that remain widely underestimated. There is variability of clinical manifestations and diagnostic criteria which leads to poor correlation between clinical signs and symptoms, therefore resulting in difficulties to assess prevalence of DED despite an improved understanding of pathogenic factors of acquired DED. However, its prevalence has been reported to range from 74% to 33% worldwide and the current study aimed to investigate the prevalence of DED and its determinants amongst people consulting at Focus Optometrists in Kwa-Mhlanga Township in Mpumalanga Province. Methodology: The current study was quantitative in nature and it followed a cross-sectional descriptive design to address the research question. The study population were people consulting at Focus Optometrists in Kwa-Mhlanga Township in Mpumalanga Province in which two standardized optometry diagnostic tests (Schimer test and the tear film break up time) were used for data collection coupled with a comprehensive case history which was taken for all participants. Data analysis was done using the STATA statistical software version 12 for Windows (STATA Corporation, College Station, Texas). Frequency tables were used to make comparisons between groups for continuous and categorical variables using student t-test, and chi-square test. P-value less than 0.05 at 95% confidence level were regarded as significant. Results: A total of 236 participants were recruited and the mean age of the participants was 39.7 in which majority of participants were females and there was a statistical significance difference in age groups of both males and females at p-value=0.011. Majority of the participants have reported to have experience of sensitivity to light vi and foreign body sensation sometimes. The poor vision and blurred vision have been reported by majority of participants sometimes and the prevalence of dry eye disease was found to be 80.9% and the risk of the dry eye disease in the current study was found significantly increasing with old age. Those who were older (35 years above) were 4.2 times more likely to develop dry eye disease at p-value <0.001 as compared to young participants. Female gender was found not to be protective of developing dry eye disease in the current and participants who were single, having secondary and education qualifications were more likely to develop dry eye disease. Participants with ocular conditions, systemic disease, surgery and those with high blood pressure were more likely to develop dry disease Conclusion: The prevalence of dry eye disease in the current study was found to be very high and therefore, patients coming to the clinic from the age of 40 with underlying systemic diseases should be screened for dry eyes. Dry eye disease can be a major contributor of refractive error in the visual systems and or can also be a sign or a symptom of hormonal or related ocular or systemic disease. More eye care awareness should be done at primary eye care level to detect the cause or to eliminate future associated symptoms.