Life space limitations in visually impaired older adults.

SIGNIFICANCE: Future work should develop and evaluate interventional strategies to help overcome visual and health-related barriers to travel in visually impaired seniors and mitigate adverse impacts of loneliness for those who do not leave town. PURPOSE: Life space refers to the area in which a person travels within a given time period. We explored whether demographics, vision, and/or health characteristics were related to restrictions in self-reported life space for visually impaired seniors. METHODS: Visually impaired (n = 114) clinical trial participants aged ≥55 years learned visual assistive iPhone apps and completed the following baseline questionnaires: Life Space, 36-Item Short-Form Health Survey, University of California, Los Angeles Loneliness Scale, and New-General Self-efficacy Scale. Multiple logistic regressions evaluated associations between life space and patient factors after accounting for their distance to the next county or state. RESULTS: During 2021 to 2023, 17%, 43%, and 70% of participants had not left their town, county, or state, respectively, in the past 3 months, or planned to in the next 3 months. Those with reduced distance best-corrected visual acuity had greater odds of not leaving the county in these time frames (odds ratio [OR] = 3.5; p=0.04). Minority race was associated with greater odds of not leaving town or the county in the past 2 weeks or future 3 months (OR = 4.3 to 6.4; p=0.009 to 0.049). Increased self-efficacy was associated with reduced odds of not leaving the state in the past 3 months, next 3 months, or past and/or future 3 months (OR = 0.54 to 0.55; p=0.02 to 0.03). Better physical function was associated with reduced odds of not leaving the state in the past 2 weeks or 3 months (OR = 0.96 to 0.98; p=0.01 to 0.04). Increased loneliness was related to greater odds of not leaving town in the past and/or future 3 months (OR = 1.8 to 2.0; p=0.007 to 0.009). CONCLUSIONS: Minority race, reduced vision, self-efficacy, and physical health were related to life space restrictions in this cohort of visually impaired seniors, whereas loneliness was greater among those who were not leaving town.

Factors related to training time and achieving proficiency with visual-assistive mobile applications in visually impaired older adults.

SIGNIFICANCE: A majority of visually impaired older adults were able to learn to proficiently use visual-assistive iPhone applications (apps) following a median 1 hour and/or multiple training sessions, which should be considered when planning vision rehabilitation service delivery, including the option for remote telerehabilitation for those who prefer that modality. PURPOSE: Older adults with low vision are increasingly using technology to improve their visual functioning. We examined whether age-related comorbidities were potential barriers to success in learning to use visual-assistive apps on a smartphone. METHODS: A clinical trial assessed visual-assistive apps in 116 older adults aged 55+ years (mean [standard deviation], 72 [10] years). Subjects were randomized to use an app (SuperVision+, Seeing AI, or Aira) preloaded to a loaner iPhone and completed one-on-one training. App proficiency was measured by the participant's ability to use the iPhone/app without cueing at the end of training sessions. Training time was recorded for the initial session and totaled after subsequent sessions. Multiple regression models explored significant factors associated with training time and proficiency. RESULTS: Median initial and total training times were 45 and 60 minutes, respectively. Increased initial and total training times were both significantly related to increased age (p<0.001), legal blindness (p<0.007), Seeing AI versus SuperVision+ app (p<0.03), and participants from New England versus California (p<0.001). Most (71%) achieved proficiency after the initial training session; those odds were significantly greater among younger participants (p=0.04), those who opted for telerehabilitation (p=0.03), those who had higher cognitive scores (p=0.04), or those who were from New England (p=0.04). The majority (90%) was ultimately proficient with the app; those odds were significantly greater among participants who already had an optical magnifier (p=0.008), but were unrelated to other factors including study site. CONCLUSIONS: Following multiple, extensive training sessions, age, mild cognitive loss, or level of visual impairment did not preclude gaining proficiency with visual-assistive apps by visually impaired seniors, but those factors were associated with longer training times. Telerehabilitation can be a viable option to provide app training remotely for visually impaired seniors who choose that modality.

Outcomes of Telerehabilitation Versus In-Office Training With Magnification Devices for Low Vision: A Randomized Controlled Trial.

Purpose: An evidence basis is lacking but needed to compare reading ability outcomes after magnification device training remotely via telerehabilitation versus in office. Methods: A multicenter randomized controlled trial at academic centers and vision rehabilitation private practices randomized 61 visually impaired adults to telerehabilitation or in-office training 1 to 4 months after dispensing new portable electronic, hand-held, or stand optical magnifiers. Telerehabilitation included loaner equipment for Zoom videoconferencing with remote control access software. Using a multilevel regression model, changes in Activity Inventory responses using Rasch analysis estimated reading ability in dimensionless log odds units (logits) (0.14-logit change corresponds with ability change expected from a one-line change in visual acuity). Results: Across 47 participants who completed the trial, reading ability with new magnifiers improved significantly by 0.61 logits on average (95% confidence interval [CI], 0.36-0.86; P < 0.001) from baseline to 1 month, and by an additional 0.44 logits on average (95% CI, 0.19-0.69; P < 0.001) from 1 to 4months (i.e., after magnifier training), with very similar significant findings for both telerehabilitation (n = 29; mean improvement = 0.44 logits; 95% CI, 0.08-0.80; P = 0.018) and in-office training (n = 18; mean improvement = 0.43 logits; 95% CI, 0.15-0.71; P = .003), and no significant difference between randomized groups across both follow-ups (95% CI, -0.43 to 0.61; P = .73). Vision, demographics, and health factors were nonsignificantly related to reading ability changes from 1 to 4 months. Conclusions: Reading ability improved after the provision of newly dispensed magnifiers, with further improvements following additional magnifier training via either telerehabilitation or in-office usual care. Translational Relevance: These findings provide support for the use of telerehabilitation to enhance reading ability with newly prescribed magnifiers as an alternative modality of care delivery.

Insights Regarding Optometric Findings of CHARGE Syndrome in a Pediatric Low Vision Clinic.

SIGNIFICANCE: CHARGE, named for common findings-coloboma, heart defects, atresia of choanae, retardation of growth and development, genital hypoplasia, and ear anomalies-is a frequent etiology of deaf-blindness. A retrospective review in a pediatric low vision clinic presented the opportunity to investigate ocular findings in this syndrome with variable clinical presentations. PURPOSE: This retrospective study reviewed ocular findings and visual function measures from low vision evaluations of patients with CHARGE syndrome, which may influence their multidisciplinary management. METHODS: A retrospective chart review was conducted by three examiners of 60 patients presenting with CHARGE syndrome at a pediatric low vision clinic. Visual acuity and contrast sensitivity were obtained using standard measures. Ocular alignment and cycloplegic refractive error measurements were recorded. Refractive findings were analyzed using vector analysis. Anterior and posterior segment findings were recorded. RESULTS: Patients ranged in age from 1 to 29 years and were followed up for a mean of 4.3 years. Best-corrected visual acuity ranged from no light perception to 20/20 Snellen equivalent. Characteristics of strabismus, occurring in 82% of patients, were reported. Contrast sensitivity was reduced in 52% of patients. Chorioretinal colobomas were reported in 88% of patients. The most common ocular findings included nystagmus (43%), microphthalmia (27%), iris coloboma (27%), and facial nerve palsy (23%). Refractive vector analysis revealed significant myopic progression of the spherical equivalent with age and a tendency for with-the-rule astigmatism and minimal obliquity. CONCLUSIONS: This retrospective review of a relatively large sample size for this rare condition outlined the most common ocular manifestations of CHARGE syndrome. Decreased visual acuity, myopic refractive error, strabismus, and reduced contrast sensitivity were common. Thus, careful optometric evaluation in this population is required, as these findings must be considered in appropriate clinical and habilitative management.

Telerehabilitation Training to Facilitate Improved Reading Ability with New Magnification Devices for Low Vision.

SIGNIFICANCE: This pilot study provides some insight about the potential benefits of telerehabilitation training to improve the reading ability of adults with low vision using magnifiers, to spur future work with larger groups. Telerehabilitation services can be implemented clinically to facilitate access to follow-up care for low vision. PURPOSE: A recent Cochrane systematic review revealed that there are no published visual function outcomes for telerehabilitation with handheld magnification devices for low vision; thus, this study aimed to provide evidence for its preliminary efficacy. METHODS: One to 4 months after receiving a new magnification device (i.e., handheld or stand optical magnifier or portable electronic magnifier), 14 adult low vision patients (with any visual acuity level or ocular diagnosis) received two training sessions at home via telerehabilitation with their vision rehabilitation provider located remotely in-office. Telerehabilitation included a loaner smartphone for Zoom videoconferencing with remote control access software. The Minnesota Low-Vision Reading Test was administered during each of the telerehabilitation sessions to assess near reading (acuity and speed) with the new magnifier. RESULTS: Mean reading acuity with the magnifier was 0.17 logMAR across subjects before training at telerehabilitation session 1, which significantly improved to 0.09 on average a few weeks later at telerehabilitation session 2 (95%confidence interval, -0.001 to -0.16; P = .047). Logarithm reading speed with the magnifier for the reading acuity level at session 1 improved significantly by 0.18 log words per minute on average for the same text size at session 2 (95% confidence interval, 0.06 to 0.29; P = .002). With the magnifier at session 2, 71% of participants gained at least 0.1 log unit in reading acuity, and half improved by >0.01 in log reading speed; all participants with increased reading speed also improved in reading acuity ( P = .02). CONCLUSIONS: These preliminary data support that telerehabilitation can enhance reading ability and efficiency with newly prescribed magnifiers as an alternative option to in-office vision rehabilitation.

Acceptability of Telerehabilitation for Magnification Devices for the Visually Impaired Using Various Approaches to Facilitate Accessibility.

Purpose: We examined different methods to reduce the burden of accessing technology for videoconferencing during telerehabilitation for magnification devices for the visually impaired. Methods: During telerehabilitation studies over the past 5 years, vision rehabilitation providers assessed and gave training to visually impaired participants with newly dispensed magnification devices at home who connected to Zoom videoconferencing via loaner tablets or smartphones with assistance from (phase 1; n = 10) investigators by phone, (phase 2; n = 11) local Lions Club volunteers in participants' homes, or (phase 3; n = 24) remote access control software in a randomized controlled trial with 13 usual care controls who received in-office training. All participants completed the same post-telerehabilitation phone survey. Results: A significantly greater proportion of phase 3 subjects indicated they strongly or mostly agreed that the technology did not interfere with the session (96%) compared to phase 1 (60%; 95% confidence interval [CI], 1.2-12.5; P = 0.03) or phase 2 (55%; 95% CI, 1.8-188; P = 0.01). The majority indicated telerehabilitation was as accurate as in person (68%), they were comfortable with telerehabilitation (91%) and interested in a future session (83%), and their magnifier use improved (79%), with no significant differences in these responses between phases (all P > 0.10), including comparisons of participants randomized to telerehabilitation or in-office training in phase 3 who reported similar overall satisfaction levels (P = 0.84). Conclusions: Participants across all phases reported high levels of acceptance for telerehabilitation, with least interference from technology using remote access control in phase 3. Translational Relevance: With accommodations for accessibility to videoconferencing technology, telerehabilitation for magnification devices can be a feasible, acceptable, and valuable option in countries with resources to support the technology.

Exploration of dynamic text presentations in bilateral central vision loss.

PURPOSE: Dynamic text presentation methods may improve reading ability in patients with central vision loss (CVL) by eliminating the need for accurate eye movements. We compared rapid serial visual presentation (RSVP) and horizontal scrolling text presentation (scrolling) on reading rate and reading acuity in CVL observers and normally-sighted controls with simulated CVL (simCVL). METHODS: CVL observers' (n = 11) central scotomas and preferred retinal loci (PRL) for each eye were determined with MAIA microperimetry and fixation analysis. SimCVL controls (n = 16) used 4° inferior eccentric viewing, enforced with an Eyelink eye-tracker. Observers read aloud 4-word phrases randomly drawn from the MNREAD sentences. Six font sizes (0.50-1.30 logMAR) were tested with the better near acuity eye and both eyes of CVL observers. Three font sizes (0.50-1.00 logMAR) were tested binocularly in simCVL controls. Text presentation duration of each word for RSVP or drift speed for scrolling was varied to determine reading rate, defined as 50% of words read correctly. In a subset of CVL observers (n = 7), relationships between PRL eccentricity, reading threshold and rate were explored. RESULTS: SimCVL controls demonstrated significantly faster reading rates for RSVP than scrolling text (p < 0.0001), and there was a significant main effect of font size (p < 0.0001). CVL patients demonstrated no significant differences in binocular reading rate between font sizes (p = 0.12) and text presentation (p = 0.25). Similar results were seen under monocular conditions. Reading acuity for RSVP and scrolling worsened with increasing PRL eccentricity (µ = 4.5°, p = 0.07). RSVP reading rate decreased significantly with increasing eccentricity (p = 0.02). CONCLUSIONS: Consistent with previous work, reading acuity worsened with increasing PRL eccentricity. RSVP and scrolling text presentations significantly affected reading rate in simCVL, but not in CVL observers, suggesting that simCVL results may not generalise to pathological CVL.

U.S. Optometrists' Reported Practices and Perceived Barriers for Low Vision Care for Mild Visual Loss.

SIGNIFICANCE: Identification of modifiable barriers to low vision rehabilitation (LVR) can inform efforts to improve practice management of patients with low vision (LV), through, for example, targeted educational programs for optometrists who do not practice LVR. PURPOSE: Mild vision loss (20/25 to 20/70) is increasing in prevalence among the aging population, yet it is unclear whether near-reading complaints (the highest presenting chief complaint) are being addressed. Studies of LVR provision by U.S. optometrists are currently lacking. This study elucidated self-reported optometric practice patterns for patients with mild vision loss. METHODS: Anonymous surveys were completed by 229 actively practicing optometrists across the United States. The survey inquired about the frequency of providing LVR for mild vision loss patients and the top barriers that prevent them from offering LVR management (including optical aids or referral). RESULTS: Compared with those moderately actively practicing LVR, twice as many (2.08×) practitioners who do not practice any LVR reported that they never prescribe near-reading add power of 4 D or greater for mild vision loss (P < .001). Among those who do not practice LVR, 39 and 11% indicated that they never prescribe any LVR management strategies for patients with visual acuity of 20/25 to 20/40 and 20/50 to 20/70, respectively. The two most commonly reported barriers to LVR indicated by about half of respondents were "cost of the LV exam and/or devices" and that "patients are not interested or would not go to an LV exam." Nearly a third of providers reported that "it is not feasible to stock magnifiers in office." CONCLUSIONS: A sizable group of non-LVR providers in the United States may not be addressing the near-vision needs of patients with mild vision loss. Several of the reported top barriers are potentially modifiable through the development of targeted educational programs for providers.

Preliminary Evaluation of Two Digital Image Processing Strategies for Head-Mounted Magnification for Low Vision Patients.

PURPOSE: In an observational clinical outcome study, we tested the effectiveness and use of the combination of two innovative approaches to magnification: a virtual bioptic telescope and a virtual projection screen, implemented with digital image processing in a head-mounted display (HMD) equipped with a high-resolution video camera and head trackers. METHODS: We recruited 30 participants with best-corrected visual acuity <20/100 in the better-seeing eye and bilateral central scotomas. Participants were trained on the HMD system, then completed a 7- to 10-day in-home trial. The Activity Inventory was administered before and after the home trial to measure the effect of system use on self-reported visual function. A simulator sickness questionnaire (SSQ) and a system-use survey were administered. Rasch analysis was used to assess outcomes. RESULTS: Significant improvements were seen in functional ability measures estimated from goal difficulty ratings (Cohen's d = 0.79, P < 0.001), and reading (d = 1.28, P < 0.001) and visual information (d = 1.11, P < 0.001) tasks. There was no improvement in patient-reported visual motor function or mobility. One participant had moderately severe discomfort symptoms after SSQ item calibration. The average patient rating of the system's use was 7.14/10. CONCLUSIONS: Use of the system resulted in functional vision improvements in reading and visual information processing. Lack of improvement in mobility and visual motor function is most likely due to limited field of view, poor depth perception, and lack of binocular disparity. TRANSLATIONAL RELEVANCE: We determine if these new image processing approaches to magnification are beneficial to low vision patients performing everyday activities.

Utilization and Abandonment of Low Vision Devices Prescribed on a Mobile Clinic.

SIGNIFICANCE: Device utilization and abandonment for patients seen on a mobile clinic are explored. Findings are informative for resource allocation in a novel low vision rehabilitation (LVR) delivery model. This study also explores the relationships between device abandonment and LVR patient-reported functional outcomes. PURPOSE: This prospective cohort study investigated low vision device utilization and abandonment in a novel mobile clinic delivery model. METHODS: A device abandonment questionnaire was administered by telephone 3 months and 1 year after mobile clinic LVR. Participants (n = 65) had previously met the U.S. definition of legal blindness and were prescribed a total of 154 devices at their low vision consultative visits. Trends in device utilization and correlations with clinical and demographic participant characteristics, as well as functional outcomes as assessed by Massof Activity Inventory, are explored. RESULTS: An average of 2.6 device recommendations were made per participant. Digital magnification, optical magnifiers, and filters were most frequently recommended. At 3 months, 29% of participants abandoned at least one device, although only 17% of received devices were abandoned. There was no significant difference in the number of devices used, abandoned, or not received at 3 months versus 1 year after LVR. Devices prescribed for reading goals were most frequently used and least often abandoned, whereas glare control and distance magnification devices were more frequently abandoned. Neither patient characteristics nor Massof Activity Inventory change score was predictive of device abandonment. There was no significant difference in the odds of device abandonment in comparison with a previous study that assessed academic outpatient LVR clinics using the same questionnaire. CONCLUSIONS: Although more device recommendations are given per patient on the mobile clinic, there is no significant difference in device abandonment for patients seen on the mobile clinic versus other outpatient LVR delivery models.

Feasibility of Telerehabilitation for Low Vision: Satisfaction Ratings by Providers and Patients.

SIGNIFICANCE: This pilot study demonstrated feasibility and acceptability of telerehabilitation between a provider in-office and a low vision patient at home as an approach to provide follow-up care to improve reading ability with magnification devices and that would help overcome barriers related to transportation and paucity of providers. PURPOSE: A recent systematic review found no publications with results on the topic of telerehabilitation for low vision. Our goal was to perform the initial steps to develop, administer, refine, and evaluate components required to deliver follow-up low vision telerehabilitation services. METHODS: Three low vision providers (ophthalmic technician or optometrist) conducted telerehabilitation sessions from their office with 10 visually impaired older adults in their homes, who recently received a handheld magnification device for reading and self-reported difficulty with returning for follow-up training at their provider's office. All except one participant had never used videoconferencing before our study, and three had never used the Internet. Participants and providers rated the use of loaner hardware devices (i.e., tablets, MiFi mobile hotspot) and Health Insurance Portability and Accountability Act-compliant, secure videoconference services during telerehabilitation sessions at which participants read MNREAD cards and received feedback on magnifier use. RESULTS: Providers reported little to no difficulty with evaluating participants' reading speed, reading accuracy, and working distance with their magnifier. Both providers and participants rated video quality as excellent to good. Audio quality ratings were variable, generally related to signal strength or technical issues during some sessions. All participants agreed that they were satisfied and comfortable receiving telerehabilitation and evaluation via videoconferencing. Eight of 10 reported that their magnifier use improved after telerehabilitation. All except one reported that they were very interested in receiving telerehabilitation services again if their visual needs change. CONCLUSIONS: Positive feedback from both participants and providers in this pilot study supports the feasibility, acceptability, and potential value of low vision telerehabilitation.

Low Vision Enhancement with Head-mounted Video Display Systems: Are We There Yet?

SIGNIFICANCE: Head-mounted video display systems and image processing as a means of enhancing low vision are ideas that have been around for more than 20 years. Recent developments in virtual and augmented reality technology and software have opened up new research opportunities that will lead to benefits for low vision patients. Since the Visionics low vision enhancement system (LVES), the first head-mounted video display LVES, was engineered 20 years ago, various other devices have come and gone with a recent resurgence of the technology over the past few years. In this article, we discuss the history of the development of LVESs, describe the current state of available technology by outlining existing systems, and explore future innovation and research in this area. Although LVESs have now been around for more than two decades, there is still much that remains to be explored. With the growing popularity and availability of virtual reality and augmented reality technologies, we can now integrate these methods within low vision rehabilitation to conduct more research on customized contrast-enhancement strategies, image motion compensation, image-remapping strategies, and binocular disparity, all while incorporating eye-tracking capabilities. Future research should use this available technology and knowledge to learn more about the visual system in the low vision patient and extract this new information to create prescribable vision enhancement solutions for the visually impaired individual.

Clinical outcomes of low vision rehabilitation delivered by a mobile clinic.

PURPOSE: This prospective cohort study examined clinical outcomes of low vision rehabilitation (LVR) delivered by a mobile clinic. METHODS: Participants were recruited from those scheduled for mobile clinic LVR and met the United States definition of legal blindness. Participants completed the Massof Activity Inventory (AI) before LVR, 3 months post-LVR, and 1 year post-LVR. Change scores and measures of clinical effect (i.e. Cohen's effect size and minimum clinically important difference, MCID) were calculated for each time point and compared. Additional participant characteristics (age, acuity, contrast sensitivity, cause of visual impairment, training recommendations, and prior LVR experience) were also explored with respect to outcome measures. RESULTS: Of the 66 participants enroled in this study, 47% had no prior LVR experience. Significant differences were noted between baseline and 3-month person measures, and between baseline and 1-year person measures. There was no significant difference between 3-month and 1-year person measures, nor was there a significant difference in change score between these two time points. At 1 year post-LVR, overall visual ability effect size was 0.74. A clinically meaningful outcome was achieved in 56% of participants at 3 months and 71% at 1 year for overall visual ability. There was no significant difference in the proportion of participants achieving MCID at 3 months vs 1 year. Of participants who completed the 1-year post-LVR AI, 59% reported a subjective worsening of vision during the study period. This subgroup also tended to have smaller 1-year change scores. CONCLUSIONS: Mobile clinic LVR is effective at expanding access to care and produces clinically meaningful outcomes comparable to those seen in other outpatient LVR delivery models.

Considering Apical Scotomas, Confusion, and Diplopia When Prescribing Prisms for Homonymous Hemianopia.

PURPOSE: While prisms are commonly prescribed for homonymous hemianopia to extend or expand the visual field, they cause potentially troubling visual side effects, including nonveridical location of perceived images, diplopia, and visual confusion. In addition, the field behind a prism at its apex is lost to an apical scotoma equal in magnitude to the amount of prism shift. The perceptual consequences of apical scotomas and the other effects of various designs were examined to consider parameters and designs that can mitigate the impact of these effects. METHODS: Various configurations of sector and peripheral prisms were analyzed, in various directions of gaze, and their visual effects were illustrated using simulated perimetry. A novel "percept" diagram was developed that yielded insights into the patient's view through the prisms. The predictions were verified perimetrically with patients. RESULTS: The diagrams distinguish between potentially beneficial field expansion via visual confusion and the pericentrally disturbing and useless effect of diplopia, and their relationship to prism power and gaze direction. They also illustrate the nonexpanding substitution of field segments of some popular prism designs. CONCLUSIONS: Yoked sector prisms have no effect at primary gaze or when gaze is directed toward the seeing hemifield, and they introduce pericentral field loss when gaze is shifted into them. When fitted unilaterally, sector prisms also have an effect only when the gaze is directed into the prism and may cause a pericentral scotoma and/or central diplopia. Peripheral prisms are effective at essentially all gaze angles. Since gaze is not directed into them, they avoid problematic pericentral effects. We derive useful recommendations for prism power and position parameters, including novel ways of fitting prisms asymmetrically. TRANSLATIONAL RELEVANCE: Clinicians will find these novel diagrams, diagramming techniques, and analyses valuable when prescribing prismatic aids for hemianopia and when designing new prism devices for patients with various types of field loss.

Peripheral prism glasses: effects of dominance, suppression, and background.

PURPOSE: Unilateral peripheral prisms for homonymous hemianopia (HH) place different images on corresponding peripheral retinal points, a rivalrous situation in which local suppression of the prism image could occur and thus limit device functionality. Detection with peripheral prisms has primarily been evaluated using conventional perimetry, where binocular rivalry is unlikely to occur. We quantified detection over more visually complex backgrounds and examined the effects of ocular dominance. METHODS: Detection rates of eight participants with HH or quadranopia and normal binocularity wearing unilateral peripheral prism glasses were determined for static perimetry targets briefly presented in the prism expansion area (in the blind hemifield) and the seeing hemifield, under monocular and binocular viewing, over uniform gray and more complex patterned backgrounds. RESULTS: Participants with normal binocularity had mixed sensory ocular dominance, demonstrated no difference in detection rates when prisms were fitted on the side of the HH or the opposite side (p > 0.2), and had detection rates in the expansion area that were not different for monocular and binocular viewing over both backgrounds (p > 0.4). However, two participants with abnormal binocularity and strong ocular dominance demonstrated reduced detection in the expansion area when prisms were fitted in front of the non-dominant eye. CONCLUSIONS: We found little evidence of local suppression of the peripheral prism image for HH patients with normal binocularity. However, in cases of strong ocular dominance, consideration should be given to fitting prisms before the dominant eye. Although these results are promising, further testing in more realistic conditions including image motion is needed.