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Optometry & Vision Science:
doi: 10.1097/OPX.0b013e31826ce145
OVS Announces

OVS Announces

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IN THIS ISSUE

We are Sloppy about Visual Acuity Reporting

Our invited author, an authority in visual acuity and low vision, provides a remarkably clear articulation of the difficulties for clinicians and researchers in reporting visual acuity. While stopping short of advocating a specific approach, he makes a strong case for requiring authors and clinicians to be more careful about defining their terms and identifying their test materials and methods of measuring visual acuity. OVS editors will take this message “to heart.” (p. 1247)

Finding a Stronger Basis for Licensure on Driving with Telescopes

Forty states in the United States have bioptic telescope licensing programs associated with driving, but there is little rigorous study that provides an evidence basis for licensure programs and training. Our author, a leading low vision researcher, responds to OVS' invitation. She offers an organizing perspective for a research agenda to provide a stronger basis for telescope licensure and training programs for driving. (p. 1249)

Finding a Better Acuity Specification than “Count Fingers”

Our authors have developed a new test (Berkeley Rudimentary Vision Test—BRVT) to allow clinicians and researchers to extend the visual acuity beyond 20/200 up to 20/16,000. They provide details of the test and its use with surprisingly simple test-card approaches. For those with worse than 20/16,000 acuity, they have produced a simple and efficient test of spatial vision that, with 13 increments, extends the range of measurement from the limits of the standard letter chart up to light perception. They share their results, testing 37 patients with poor acuity in this measurable range. (p. 1257)

When the Mind Knows and the Eyes Don't See!

Volume perimetry permits measurement of volume visual fields in front and beyond where the patient fixates. The authors show anterior and posterior volume visual fields can vary substantially from conventional binocular perimetry measured at the fixation plane, revealing blind areas not otherwise identified. They suggest these volume scotomas are likely to impair functional vision such as driving (for bitemporal hemianopia) and near work with small hand tools (for binasal scotomas). Consideration of volume scotomas can help provide more effective vision rehabilitation and counseling. (p. 1265)

Big Impact of Reduced Contrast Print in Older Patients

Even in the absence of eye disease, many older adults have reduced contrast sensitivity. The authors analyze data from a large (>2500 aged >64 years) population-based study and show that reduced contrast sensitivity is likely to limit optimal reading of newsprint for more than one-half of the older population in the United States. Presenting text in a format available on a computer monitor might dramatically increase accessibility to the written word in this group of people. (p. 1276)

Reduced Contrast Disproportionately Impacts Reading for Glaucoma Patients

Perhaps unexpectedly, our authors' study found glaucoma patients are disproportionately affected by reduced contrast text when reading. They note an average reduction in reading speed caused by a reduction in letter contrast from 100 to 20% is significantly more apparent in patients with glaucoma when compared with visually healthy people of similar age and cognitive/reading ability. (p. 1282)

Does Increasing Letter Spacing, to Reduce Crowding, Help Low Vision Patients Read?

Apparently not! Our authors tested a range of letter-spacing presentations on reading speed for patients with central vision loss. They concluded that increased letter spacing beyond the standard size, which presumably reduces crowding among letters in text, does not improve reading speed for these people. In fact, the optimal letter spacing for reading can be predicted based on the preferred retinal locus (PRL) for fixation. (p. 1288)

Seeing Steps and Ramps with Low Acuity

Study participants with simulated low vision judged whether a step, ramp, or neither was present ahead on a sidewalk. Surprisingly, performance was lower with the textured surface than with a uniform surface, perhaps because the texture masked visual cues necessary for recognition. Subjects performed better in walking trials than in stationary trials, possibly because they could take advantage of visual cues only present during motion. (p. 1299)

Some Real Challenges Ahead for Implanted Prosthetic Vision

Our authors' study of retinitis pigmentosa (RP) participants with severely restricted fields, who have been implanted with an artificial silicon retina, demonstrates that mobility might not be improved with this prosthetic vision. Based on their study, the authors call for a research agenda that emphasizes the importance of developing individualized assessments, identifying specific items of orientation rather than mobility for measuring the effect of prosthetic vision, and to develop and evaluate instructional programs that may be needed for obtaining the full benefit of this new technology. (p. 1308)

Predicting Reading Performance in Low Vision Patients

The authors provide guidelines for clinicians to predict the reading performance of their low vision patients. They propose that reading acuity at a fixed working distance and contrast sensitivity can be used to predict accessible text size, optimum acuity reserve, and reading speed with magnifiers. (p. 1316)

Reading Additions Useful for Young Low Vision Patients

Although most children and young adults with low vision have active accommodation, they use a reduced reading distance. Using a new measure of reading performance that they believe better estimates everyday reading ability, they demonstrate that reading additions improve near visual acuity and short-term reading performance. They urge inclusion of this measure of reading performance in low vision assessments. (p. 1327)

AMD Low Vision Patients Impressively Compliant with Optical Devices

In a study of almost 200 age-related macular degeneration (AMD) first-time visitors to a low vision clinic, the authors were encouraged by the high rate of low vision device usage that was maintained over a 3-month period. Device abandonment was very low, with <1% of patients never using their device. In >75% of cases, the devices were rated as moderately to extremely useful by the patients, being rated only slightly less useful for high plus spectacles. (p. 1336)

Patients Without String Ocular Dominance are Successful with Peripheral Prism Glasses

Peripheral prism has been used in low vision to improve visual field function binocularly. Logically, one might expect that unilateral peripheral prisms for homonymous hemianopia would place different images on corresponding peripheral retinal points, a rivalrous situation in which local suppression of the prism image could occur and limit the usefulness of that intervention. The good news is that the authors found no evidence of any such suppression of the prism image for patients with normal binocularity but no strong sensory ocular dominance, even over a visually complex background. (p. 1343)

Expanding the Visual Field with Torsional Strabismus and ARC

Exotropia in congenital homonymous hemianopia has been reported to provide field expansion that is more useful when accompanied with anomalous retinal correspondence (ARC). Our authors describe the role of torsional strabismus in expanding the visual field for a patient who has hemianopic field defect. Using a computerized dichoptic perimeter, the authors noted field expansion was more useful when combined with torsional (and lateral) harmonious ARC. (p. 1353)

Is Visual Search a Good Measure of the Effectiveness of Image Enhancement?

People with visual impairment often have difficulty watching TV and movies. In an attempt to overcome a major problem of quantifying any enhancements of low vision, the authors used a visual search task as a performance measure and related that to how much participants with visual impairment preferred the same enhancements. Disappointingly, they found that the two measures were not related, leading the authors to propose some future contrast studies that might better address the challenge. (p. 1364)

Training Fixation with Peripheral Vision a Key to Novel Rehabilitation Approaches?

Understanding short-term eye movement adaptations after scotoma onset seems critical to the development of novel rehabilitation interventions. Using natural scenes, normally sighted participants searched with simulated central vision loss and revealed that fixation instability associated with the use of peripheral vision was the primary problem. The authors propose that measures to counteract fixation instability, either by means of meridian-specific training or manipulation of stimuli along the axis of greatest fixation instability (e.g., magnification, contrast enhancement), may facilitate the development of better viewing strategies for patients with central vision loss. (p. 1374)

Simulated Central Scotomas and Visual Search Show Promise of Quantification

In a search for a performance measure in natural scenes for AMD patients, our authors simulated central vision loss in normally sighted participants. Their novel contour-based image-enhancement techniques demonstrated a beneficial effect in the older participants. Perhaps more importantly, they also found a robust correlation between subjective task-specific preference and objective visual-search performance with natural scenes. (p. 1385)

Low Vision Patients are Unaware of Visual Field Loss

In their initial low vision rehabilitation evaluation, more than one-half of >135 AMD patients with binocular scotomas were completely unaware of any defect. The others reported experiences of things “disappearing,” but only 1.5% reported seeing their defect fleetingly (generally on waking up). The authors believe there may be benefits to helping patients become aware of their scotoma in rehabilitation programs. (p. 1395)

Low Vision Rehabilitation, Particularly if Maintained, Improves Quality of Life

The authors demonstrate improvements in quality of life after low vision rehabilitation by using both the Impact of Vision Impairment Questionnaire and the Veterans Affairs Low-Vision Visual Functioning Questionnaire (VA LV VFQ-48). The timing of the observed changes varied between the two questionnaires, reflecting the different content of these instruments and the timing of delivery of multidisciplinary services. The authors also suggest that continued rehabilitation may be warranted to maintain quality of life. (p. 1399)

Quality of Life for Children with Low Vision

Focus groups of children with vision impairment aged 6 to 12 years, and their parents, revealed that pediatric vision impairment has significant effects on health-related quality of life, as reported by both children with vision impairment and their parents (in their own words). These findings should provide the content to guide construction of a survey instrument to assess vision-specific health-related quality of life in children with vision impairment. (p. 1409)

For Low Vision Does Correcting Higher-order Aberrations Help Beyond Spectacle Correction?

Apparently so in this interesting case report of a 68-year-old woman with bilateral Stargardt disease and preferred retinal location 25 degrees from the fovea! The authors report improvement in resolution acuity after correcting the higher-order aberrations using adaptive optics in this subject. This may be the first report of such a correction and its positive effect for a low vision patient. (p. 1417)

© 2012 American Academy of Optometry

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