Biomedical subjects

Alex R Bowers

Publications and source records attributed to Alex R Bowers.

7 recordsLinked to original sources

PubMed2005

Short-term in-office practice improves reading performance with stand magnifiers for people with AMD.

PURPOSE: People with low vision often use optical low vision aids to assist reading. There have been numerous training programs recommended to train people using magnifiers for reading. However, most of the programs are time consuming and labor intensive. In this study, we investigated the effects of home-based large print reading practice on reading performance when stand magnifiers (STM's) are first prescribed. METHODS: Thirty-two subjects with age-related macular degeneration (AMD) and with minimal experience in using magnifiers for reading were recruited. They were divided into three groups: control, practice 1 (P1), and practice 2 (P2). Before the prescription of STM's, all the subjects were given the same amount of in-office practice with the STM (weeks 0 to 2). In addition, in these 2 weeks, P1 and P2 subjects were given large print books to read daily at home. P2 subjects were required to read the large print books through a reduced field of view. The control group subjects received no additional reading practice. Reading rates with and without STM's on passages of text were assessed for all the subjects regularly for 20 weeks. RESULTS: There were no significant differences between the control, P1, and P2 groups in the increase in reading rate with STM (p = 0.29). At week 0, reading rate for small print with STM was significantly slower than reading rate on the equivalent-sized large print (p = 0.004); however, as time went on, reading rate with STM's increased significantly (p = 0.02). After 2 weeks of in-office magnifier practice and repeated measures of reading rate with STM, reading rate with STM had improved such that it was not significantly different from reading rate on large print (p = 0.11). CONCLUSION: Supervised, short-term, in-office practice with the magnifier was effective in improving magnifier reading performance to achieve maximum reading rate. Additional large print reading practice did not result in any greater improvement in reading rate than in-office magnifier practice alone.

Aged↗

PubMed2005

Bioptic telescopes meet the needs of drivers with moderate visual acuity loss.

PURPOSE: Visually impaired people are permitted to use bioptic telescopes for driving in many states in the United States. However, it has been suggested that the telescope is used only to meet the visual acuity criteria for licensure. In this study, a survey was used to establish the extent to which bioptic telescopes are used by and meet the driving needs of people with moderately reduced visual acuity. METHODS: A cross-sectional survey of a convenience sample of 58 bioptic drivers was administered by telephone interview. Bioptic telescope usage patterns were quantified with questions designed specifically for the study. Driving patterns were quantified by use of the Driving Habits Questionnaire. Subjects were recruited from four sources across the United States to ensure a range of bioptic training and driving experience. RESULTS: The majority (74%) rated the bioptic telescope as very helpful, and almost all (90%) would continue to use it for driving, even if it were not required for driving licensure; however, only 62% reported always wearing the bioptic when driving. Subjects had relatively unrestricted driving habits, driving a mean of 222 +/- 211 miles per week, and 85% aged < or =65 years drove to work. With the exception of driving in rain, in bright sunlight, and at night, there was little difficulty with driving in a variety of situations, and levels of driving avoidance due to vision impairment were low (<10%). CONCLUSIONS: The bioptic telescope met the (self-reported) driving needs of the majority of visually impaired drivers in this survey and was found to be a useful aid for tasks requiring resolution of detail.

Adolescent↗

PubMed2005

Establishing Mobility Measures to Assess the Effectiveness of Night Vision Devices: Results of a Pilot Study.

In preparation for an evaluation of night vision devices, an exploratory study was conducted to gain initial experience with the sensitivity of chosen mobility measures under night conditions. The measures included cane contacts and object recognition distances. Results provide preliminary evidence that these two measures may be sensitive to the effects of a night vision device.

Journal Article↗

PubMed2004

Preferred retinal locus and reading rate with four dynamic text presentation formats.

BACKGROUND: Electronic display devices hold the potential to improve access to written material by people with low vision. For those with central field loss, the optimal form of electronic text presentation may vary according to the location of the preferred retinal locus, but this has never been investigated. In this study, we examined the relationship between preferred retinal locus location and reading rate for four electronic display formats (rapid serial visual presentation, horizontal scroll, vertical scroll, and page). METHODS: Short sentences were presented in each format to 35 low-vision (most with central field loss) and 14 age-matched control subjects. Subjects read aloud to determine maximum oral reading rate and read silently to determine preferred silent reading rate. RESULTS: With the exception of page format, maximum oral reading rates were faster than silent preferred reading rates for both groups of subjects. For the low-vision group, there was no significant difference in maximum oral reading rates between the four display formats; and when reading at a preferred silent rate, page format was faster than the other three formats. Though page format was read more quickly, half of the low-vision subjects preferred the horizontal-scroll format. Contrary to our predictions, there was no significant effect of preferred retinal locus location (vertical vs. lateral) on reading rate and no significant interaction between preferred retinal locus location and display format. CONCLUSIONS: The differences between maximum oral and preferred silent reading rates and the lack of a relationship between reading rates and preferred display format reinforce the importance of patient preference in the evaluation and selection of a device or display format during rehabilitation.

Adult↗

PubMed2004

Evaluation of a prototype Minified Augmented-View device for patients with impaired night vision.

An evaluation was carried out of the first prototype (LV-3) of a new night vision device, which incorporates visual field expansion through minification (Minified Augmented-View), to provide feedback for continuing development. Six subjects with night blindness completed visual function measurements and indoor mobility assessments without a device, with the LV-3 and with a commercially available comparison device (the Multi-Vision) at light levels representative of well lit and poorly lit streets. Device performance and potential benefits in real-world situations were evaluated at four outdoor locations (well lit to very dark). Results indicate that the see-through nature and spectacle-frame mounting of the LV-3 address some of the cosmetic and ergonomic disadvantages of currently available devices; however insufficient light sensitivity of the prototype camera limited LV-3 performance. With improved camera sensitivity and full implementation of the Minified-Contours Augmented-View concept in the next prototype, patients might be able to make better use of the novel field expansion and vision multiplexing features to aid outdoor night mobility.

Adult↗

PubMed2002

Determining magnification for reading with low vision.

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 (AMD) 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 magnifiers. 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 subjects' 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 rates 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.

Aged↗

PubMed2001

Illumination and reading performance in age-related macular degeneration.

BACKGROUND: Previous studies have compared low vision reading performance at optimal task illuminance and consulting room illuminance (500 to 600 lux). However, it is uncertain the extent to which low vision reading performance can be improved when task illumination is increased from levels more representative of those found in the typical living room (50 lux) to levels likely to maximise performance. METHODS: Reading performance of 20 subjects with age-related macular degeneration (AMD) was assessed for a range of print sizes using sentence reading charts at six levels of task illuminance (50 to 5,000 lux). Subjects read without low vision devices. RESULTS: Sentence reading acuity and critical print size improved by a factor of two over the 50 to 5,000 lux range, while maximum reading rate improved by a factor of 1.4. For the majority of subjects (70 per cent), the optimal task illuminance (determined objectively) was higher (median 3,500 lux) than the subjectively preferred task illuminance (median 2,450 lux). Reading performance was significantly better at the optimal illuminance than at illuminances equivalent to those found in the domestic environment (50 lux) or consulting room (600 lux). CONCLUSIONS: The majority of AMD patients will require task illumination of at least 2,000 lux to maximise reading performance. Optimal illumination should be determined individually for each patient using both objective measures of performance, such as reading acuity, and subjective assessments of visual comfort.

Journal Article↗