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Free to read The past 40 years has seen a great expansion in low-vision research, which has changed low-vision teaching and our clinical management of people with low vision. Australian optometrists have contributed significantly to this research and the development of multidisciplinary low-vision services. This paper reviews the research that has shaped our clinical assessment and patient management for reading by adults with low vision. The major improvements in clinical assessment of low vision for reading were brought about by the improvements in distance and near visual acuity measurements during the 1970s and research during the 1980s and 1990s showing the factors affecting the reading rate. These changes, together with a different method for representing the magnification provided by optical and electronic systems, allows a scientific, logical and practical method for prescribing magnification. An illustration of the step-by-step approach for prescribing magnification for low-vision reading that is easy to apply in any clinical practice is included.

PURPOSE: To examine the visual predictors of falls and injurious falls among older adults with glaucoma. METHODS: Prospective falls data were collected for 71 community-dwelling adults with primary open-angle glaucoma, mean age 73.9 ± 5.7 years, for one year using monthly falls diaries. Baseline assessment of central visual function included high-contrast visual acuity and Pelli-Robson contrast sensitivity. Binocular integrated visual fields were derived from monocular Humphrey Field Analyser plots. Rate ratios (RR) for falls and injurious falls with 95% confidence intervals (CIs) were based on negative binomial regression models. RESULTS: During the one year follow-up, 31 (44%) participants experienced at least one fall and 22 (31%) experienced falls that resulted in an injury. Greater visual impairment was associated with increased falls rate, independent of age and gender. In a multivariate model, more extensive field loss in the inferior region was associated with higher rate of falls (RR 1.57, 95%CI 1.06, 2.32) and falls with injury (RR 1.80, 95%CI 1.12, 2.98), adjusted for all other vision measures and potential confounding factors. Visual acuity, contrast sensitivity, and superior field loss were not associated with the rate of falls; topical beta-blocker use was also not associated with increased falls risk. CONCLUSIONS: Falls are common among older adults with glaucoma and occur more frequently in those with greater visual impairment, particularly in the inferior field region. This finding highlights the importance of the inferior visual field region in falls risk and assists in identifying older adults with glaucoma at risk of future falls, for whom potential interventions should be targeted. KEY WORDS: glaucoma, visual field, visual impairment, falls, injury

Free to read Purpose: To examine the relationship between visual impairment and functional status in a community-dwelling sample of older adults with glaucoma. Methods: This study included 74 community-dwelling older adults with open-angle glaucoma (aged 74 ± 6 years). Assessment of central vision included high-contrast visual acuity and Pelli-Robson contrast sensitivity. Binocular integrated visual fields were derived from merged monocular Humphrey Field Analyser visual field plots. Functional status outcome measures included physical performance tests (6-min walk test, timed up and go test and lower limb strength), a physical activity questionnaire (Physical Activity Scale for the Elderly) and an overall functional status score. Correlation and linear regression analyses, adjusting for age and gender, examined the association between visual impairment and functional status outcomes. Results: Greater levels of visual impairment were significantly associated with lower levels of functional status among community-dwelling older adults with glaucoma, independent of age and gender. Specifically, lower levels of visual function were associated with slower timed up and go performance, weaker lower limb strength, lower self-reported physical activity, and lower overall functional status scores. Of the components of vision examined, the inferior visual field and contrast factors were the strongest predictors of these functional outcomes, whereas the superior visual field factor was not related to functional status. Conclusions: Greater visual impairment, particularly in the inferior visual field and loss of contrast sensitivity, was associated with poorer functional status among older adults with glaucoma. The findings of this study highlight the potential links between visual impairment and the onset of functional decline. Interventions which promote physical activity among older adults with glaucoma may assist in preventing functional decline, frailty and falls, and impr

The care of low-vision patients is termed vision rehabilitation, and optometrists have an essential role to play in the provision of vision rehabilitation services. Ideally, if patients stay with one optometrist or practice, their low-vision care becomes part of a continuum of eye care, from the time when they had normal vision. If progressive vision loss occurs, the role of the optometrist changes from primary eye care only to one of monitoring vision loss and gradually introducing low-vision care, especially magnification and advice on lighting and contrast, in conjunction with other vision rehabilitation professionals.

Purpose: Students often read for long periods and prolonged reading practice may be important for developing reading skills. For students with low vision, reading at a close working distance imposes high demands on their near visual functions, which might make it difficult to sustain prolonged reading. The aim of this study was to investigate the performance of a prolonged reading task by students with low vision. Method: Forty students with low vision, aged from eight to 20 years and without any intellectual, reading or learning disability, were recruited through the Paediatric Low Vision Clinic, Buranda, Queensland. Following a preliminary vision examination, reading performance measures—critical print size (CPS), maximum oral reading rates (MORR), near text visual acuity— were recorded using the Bailey-Lovie text reading charts before and after a 30-minute prolonged reading task. Results: The mean age of the participants was 13.03 ± 3 years. The distance and near visual acuities ranged between -0.1 to 1.24 logMAR and 0.0 to 1.60 logMAR, respectively. The mean working distance of the participants was 11.2 ± 5.8 cm. Most of the participants (65 per cent) in this study were able to complete the prolonged reading task. Overall, there was no significant change in CPS, MORR and near text visual acuity following the prolonged task (p > 0.05). MORR was significantly correlated to age and near text visual acuity (p < 0.05). Conclusions: In this study, students with low vision were able to maintain their reading performance over a 30-minute prolonged reading task. Overall, there was no significant increase or decrease in reading performance following a prolonged reading task performed at their habitual close working distances but there were wide individual variations within the group.

Purpose: To investigate the impact of glaucomatous visual impairment on postural sway and falls among older adults.Methods: The sample comprised 72 community-dwelling older adults with open-angle glaucoma, aged 74.0 5.8 years (range 62 to 90 years). Measures of visual function included binocular visual acuity (high-contrast), binocular contrast sensitivity (Pelli- Robson) and binocular visual fields (merged monocular HFA 24-2 SITA-Std). Postural stability was assessed under four conditions: eyes open and closed, on a firm and on a foam surface. Falls were monitored for six months with prospective falls diaries. Regression models, adjusting for age and gender, examined the association between vision measures and postural stability (linear regression) and the number of falls (negative binomial regression). Results: Greater visual field loss was significantly associated with poorer postural stability with eyes open, both on firm (r = 0.34, p < 0.01) and foam (r = 0.45, p < 0.001) surfaces. Eighteen (25 per cent) participants experienced at least one fall: 12 (17 per cent) participants fell only once and six (eight per cent) participants fell two or more times (up to five falls). Visual field loss was significantly associated with falling; the rate of falls doubled for every 10 dB reduction in field sensitivity (rate ratio = 1.08, 95% CI = 1.02–1.13). Importantly, in a model comprising upper and lower field sensitivity, only lower field loss was significantly associated with the number of falls (rate ratio = 1.17, 95% CI = 1.04–1.33). Conclusions: Binocular visual field loss was significantly associated with postural instability and falls among older adults with glaucoma. These findings provide valuable directions for developing falls risk assessment and falls prevention strategies for this population.

Background: When reading with a stand magnifier (SM), navigation along each line of text and retracing back to the correct position at the beginning of the next line has been suggested as a major difficulty for people with low vision. In this study, we evaluated the immediate impact of using a simple and inexpensive line guide on navigation performance.--- Methods: Twenty-nine participants with age-related macular degeneration read short passages of text using their habitual SM with and without a temporary line guide attached. Magnifier movements were recorded using a 3 SPACE Isotrak system. Reading time, magnifier movement strategies, navigation times and navigation errors were determined. A short questionnaire was used to quantify participants’ perceived difficulties with page navigation and their preference for reading with or without the line guide.--- Results: For some participants, the line guide improved the control of the vertical positioning of the SM when reading along a line (p=0.01), but it increased the number of corrective vertical movements at the end of the retrace (p=0.001). There was a small but significant decrease (about 6wpm) in reading speed and increase in navigation times (p<0.05) when using the line guide; however 48% participants indicated a preference for reading with it attached to their SM. There was a trend (p=0.08) for those who preferred the line guide to report greater habitual difficulties with SM manipulation.--- Conclusion: After only minimal instruction in how to use the line guide, forward navigation control improved, but the design of the guide made retracing the SM to the start of the next line more difficult resulting in slower reading speeds. Nevertheless 48% of participants expressed a preference for having the line guide attached to their SM. Improvements to the design of the line guide and strategies that may improve retrace navigation performance are suggested.

Purpose: To examine the visual factors associated with falling among older adults with glaucoma.----- Methods: 65 community-dwelling older adults with open-angle glaucoma, aged 75 + or- 6 years (from 65 to 90 years), participated in this study. an eye examination was performed, including tests of binocular visual acuity (high contrast), binocular sensitivity (Pelli-Robson), visual fields (monocular Humphrey Field Analyser SITA 24-2 and binocular 96-point visual field) and nerve fibre layer thickness with the Stratus Optical Coherence Tomographer. Visual field loss was graded according to the Advanced Glaucoma intervention Study (AGIS) criteria. Dta were also collected on demographic characteristics (age and gender) and physical performance measures (self-reported physical activity and six-minute walk test). The main outcome measure was he number of falls reported in the previous 12 months. the relationship between the vision measures and number of falls was evaluated using negative binomial regression and incidence rate ratios (IRR) adjusted for potential confounding factors (age, gender and physical performance measures).----- Results: In the previous 12 months, 23 (35%) participants experienced at least one fall: 16 (25%) participants fell only once and seven (11%) participants fell two or more times (up to six falls). After adjusting for the potential confounding factors, the negative binomial models showed that the rate of falls doubled for every 9dB reduction in the better-eye 24-2 mean deviation (IRR 1.08), 8 point increase in the better-eye AGIS score (IRR 1.09), or 35 points missed on the binocular 96-point visual field (IRR 1.02). Visual acuity, contrast sensitivity and retinal nerve fibre thickness were not associated with falling.

Purpose: The aim of this study was to determine if useful field of view (UFV) measures help to predict aspects of orientation and mobility in people with visual impairment. The UFV is a composite measure of visual attention, ability to detect objects in the presence of clutter and basic visual functions such as visual field loss and contrast sensitivity. Methods: Thirty five participants aged 20-80 years with low vision due to a variety of visual disorders took part. Mobility around a partly indoor and exterior real-life mobility course was measured, together with UFV and clinical measures of contrast sensitivity (CS), visual fields and visual acuity. Two series of models were considered; Series 1 using the UFV scores as measured and Series 2 using the UFV scores corrected for visual field loss (only counting errors in areas of intact visual field).--- Results: UFV was found to be an important predictor of some aspects of mobility performance. Mobility errors were best predicted by uncorrected UFV (R2=0.38), although CS was also a good predictor. Walking speed and preferred walking speed (PWS) were best predicted by uncorrected UFV and age (R2=0.575 and 0.573 respectively). The visual detection distance and visual identification distances were best predicted by clinical vision measures, such as contrast sensitivity, visual fields, and central vision function. The percent PWS was not predicted by any of the measures we used. None of these models was improved by the addition of the corrected UFV scores.--- Conclusions: These results indicate that attention and the presence of distractors, as well as visual function and age, are important factors in orientation and mobility performance, in particular mobility errors, walking speed and PWS.

Purpose. To investigate the effect of visual impairment on postural sway among older adults with open-angle glaucoma. Methods. This study included 54 community-dwelling participants with open-angle glaucoma, aged 65 and older. Binocular visual field loss was estimated from merged monocular Humphrey Field Analyzer visual field results and retinal nerve fiber layer (RNFL) thickness was obtained from the Stratus Optical Coherence Tomographer. Postural sway was measured under four conditions: eyes open and closed, on a firm, and a foam surface. Data were collected for additional vision measures (visual acuity and contrast sensitivity), physical performance measures (self-reported physical activity levels and 6-min walk test), and demographic measures (age, gender, body mass index, and medical history). Multivariate linear regressions, adjusting for confounding factors, were performed to determine the association between visual loss and postural sway. Results. Participants with greater binocular visual field loss or thinner RNFL thickness showed increased postural sway, both on firm and foam surfaces, independent of age, gender, body mass index, and physical performance levels. These visual loss measures were significant predictors of postural sway, explaining almost 20% of its variance on the foam surface. Furthermore, participants with greater inferior hemifield visual field loss showed increased postural sway on the foam surface. Increasing glaucomatous visual impairment was accompanied by a steady decrease of the visual contribution to postural control. Conclusion. Among older adults with glaucoma, greater visual field loss or thinner RNFL thickness is associated with reduced postural stability. This postural instability may be a contributing factor in the increased risk of falls among older adults with glaucoma.

Purpose:To investigate rod-mediated function with the multifocal electroretinogram (mfERG) in normal subjects and in subjects with early age-related maculopathy (ARM). Methods and subjects: Thirty subjects were tested with the rod-mediated mfERG; 10 healthy young subjects (mean age 31 years) and 10 healthy older subjects (mean age 71 years) formed groups 1 and 2 respectively and 10 early ARM subjects formed group 3 (mean age 71 years). To approximate the influence of cataract, five subjects of group 1 were re-tested with added neutral density filters (0.3 ND) (group 4). The first-order N1P1 amplitude and P1 latency responses were analysed. The unscaled 61 hexagons were averaged into 4 rings to examine topographical differences. Funduscopic and lens changes as defined by Age-Related Eye Disease Study Research Group criteria (AREDS) were correlated with the mfERG parameters. Results: P1 latencies were significantly delayed in groups 2 (p=0.02) and 3 (p<0.001) compared to group 1. Group 3 showed significantly delayed results compared to groups 2 and 4 (p<0.01). In contrast there were no significant differences in N1P1 amplitudes between groups but there was a significant location effect for all groups with highest mean amplitudes for ring 4 (p<0.01). Significantly longer P1 latencies (p<0.05) were related to more advanced fundus changes. Conclusions: The rod-mediated mfERG is affected by aging and early ARM and is correlated with funduscopic changes. Although a preretinal cause cannot be excluded the findings suggest neuronal transmission alterations at the post-receptoral level in aging and in early ARM.

The concept of older adults contributing to society in a meaningful way has been termed ‘active ageing’. Active ageing reflects changes in prevailing theories of social and psychological aspects of ageing, with a focus on individuals' strengths as opposed to their deficits or pathology. In order to explore predictors of active ageing, the Australian Active Ageing (Triple A) project group undertook a national postal survey of participants over the age of 50 years recruited randomly through their 2004 membership of a large Australia-wide senior's organisation. The survey comprised 178 items covering paid and voluntary work, learning, social, spiritual, emotional, health and home, life events and demographic items. A 45% response rate (2655 returned surveys) reflected an expected balance of gender, age and geographic representation of participants. The data were analysed using data mining techniques to represent generalizations on individual situations. Data mining identifies the valid, novel, potentially useful and understandable patterns and trends in data. The results based on the clustering mining technique indicate that physical and emotional health combined with the desire to learn were the most significant factors when considering active ageing. The findings suggest that remaining active in later life is not only directly related to the maintenance of emotional and physical health, but may be significantly intertwined with the opportunity to engage in on-going learning activities that are relevant to the individual. The findings of this study suggest that practitioners and policy makers need to incorporate older peoples' learning needs within service and policy framework developments.

Purpose. To investigate the multifocal electroretinogram (mfERG) and subjective function in early age-related maculopathy (ARM). Methods. Seventeen subjects with early ARM with visual acuity (VA) of 6/12 or better and 20 age-matched control subjects were examined. We assessed mfERGs, high and low contrast distance VA, near VA, low luminance VA, contrast sensitivity, saturated and desaturated Panel D-15 and visual fields (mean sensitivity). The mfERG responses were analysed by comparing central-overall (method 1) and superior-inferior (method 2) ratios. Results. The mfERG did not discriminate between the groups whereas colour vision (tritan deficiency), contrast sensitivity, and high contrast and low contrast VA showed significantly reduced responses for the early ARM group compared with the control group (p ≤ 0.01). The mfERG first-order kernel responses correlated significantly with the desaturated D-15 in both methods (r = −0.5, p ≤ 0.05). Fundus grading was not correlated with the mfERG measures. Conclusions. Although the mfERG correlated significantly with the desaturated D-15 in early ARM, suggesting it operates at a sensitive level, it failed to discriminate between the control and ARM groups. In our sample, the subjective function measures were more sensitive than the mfERG measures.

Background: In the past, practitioners have used distance and/or near visual acuity (VA) to calculate required magnification for low vision aids. Magnification was usually under-estimated when compared with the final magnification prescribed. Recent studies have emphasised the importance of acuity reserve in determining the required magnification for optimum reading rate. Two different approaches have been proposed for the appropriate acuity reserve to use in calculating magnification. These are a fixed acuity reserve of 0.3 log unit or an individual determination of optimum acuity reserve. The aim of this study was to investigate the magnification and reading rates with low vision aids selected by the two methods. Methods: Nineteen low vision subjects with age-related macular degeneration (ARM) who were experienced magnifier-users were recruited. Reading rates and near VA with low vision aids determined by the fixed and individual acuity reserve methods were compared with the same measures made with the subjects’ own magnification. Results: There were no significant differences in reading rate and near VA measured with low vision aids selected by either the fixed or individual acuity reserve methods or the subject’s own magnifiers. Reading rate with low vision aids was not significantly different from reading rate for large print with conventional near additions. Thus, for experienced users, magnifiers do not cause reduced reading rate. Conclusions: The fixed acuity reserve method is simple to apply as only near VA and print size of the target reading task are required. For the individual acuity reserve method, reading rate at different print sizes need to be measured. We recommend the use of a fixed acuity reserve (0.3 log unit) for the calculation of required magnification for low vision patients. If near VA or reading rate are not satisfactory with the magnification calculated by this method, individual assessment of required acuity reserve is necessary.

Purpose. To investigate the effects of age-related macular degeneration (ARMD) on mobility performance and to identify the vision determinants of mobility in subjects with ARMD. Methods. Walking speed and the number of obstacle contacts made on a 79-m indoor mobility course were measured in 21 subjects with ARMD and 11 age-matched subjects with normal vision. The mobility measures were transformed to percentage preferred walking speed and contacts score. The vision functions assessed included binocular visual acuity, contrast sensitivity, and visual field. Results. In this study, subjects with ARMD did not walk significantly slower or make significantly more obstacle contacts on the mobility course than the normally sighted subjects of similar age. Between 29% and 35% of the variance in the ARMD mobility performance was accounted for by visual field and contrast sensitivity measures. The most significant predictor of mobility performance scored as percentage preferred walking speed was the size of a binocular central scotoma. Conclusion. As the size of a binocular central scotoma increases, mobility performance decreases.

Purpose: We assessed repeatability and intercorrelations of five standard vision tests in subjects with normal vision. Methods: Seventy-eight subjects (aged 21 to 68 years) completed five measurements each of high- and low-contrast visual acuity, near visual acuity and contrast sensitivity (Pelli-Robson chart). Results: Except for correlations between high- and low-contrast visual acuity (r = 0.78), intercorrelations between tests were low to moderate (r < 0.5). For each measure, variability for the group was about one line on the chart (one triplet for the Pelli-Robson chart) and the minimum variability for an individual subject was about one third of this. On average, 1 to 2 lines can be expected to be lost over the normal lifespan on each test. Variability in responses did not increase significantly with age for any test. Conclusions: The criterion for judging change on commonly used clinical vision tests is about one line for subjects over a wide age range.

This study investigated the orientation and mobility (O&M) performance of subjects with age-related macular degeneration (ARMD). Mobility performance, assessed as walking speed, percentage preferred waking speed (PPWS), and number of contacts with obstacles, was measured on 21 subjects with ARMD and 11 age-matched controls using a 79-meter indoor mobility course. Orientation was assessed by asking subjects to perform two tasks. Similar trends were found for results using walking speed and PPWS, except that age had a significant effect on walking speed. No significant difference in mobility performance was found between ARMD and control subjects. Reduced illumination resulted in worse mobility performance by both subject groups.

Letter to the editor

Most patients with low vision request help with reading. Despite improvements in the assessment of visual functions, determining the appropriate magnification for reading still often involves a trial and error approach. Recent research has shown that with accurate and systematic assessments of vision, the required magnification can be predicted but this magnification needs to be much higher than has been previously recommended. This paper presents a systematic approach to enable practitioners to determine the power of a near addition or simple magnifier needed to assist patients with mild or moderate low vision who may present seeking help for reading. Guidelines for appropriate referral to low vision services are also provided.