Harmonization of Outcomes and Vision Endpoints in Vision Restoration Trials: Recommendations from the International HOVER Taskforce

Ayton, Lauren N; Rizzo, Joseph F.; Bailey, Ian L.; Colenbrander, August; Dagnelie, Gislin; Geruschat, Duane R.; Hessburg, Philip C.; McCarthy, Chris; Petoe, Matthew A.; Rubin, Gary S.; Troyk, Philip R.

doi:10.1167/tvst.9.8.25

Cited by 51 publications

(47 citation statements)

References 148 publications

(252 reference statements)

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“…A retinal implant single sensor may be inferior to an external single sensor device because of the temporal characteristics of a retinal implant, such as desensitization and phosphenes persistence. 24 , 33 The localization of a stimulus with retinal implant may be erroneous because of the effect of eye movements uncorrelated with a head-mounted camera, as shown by Caspi et al 34 Thus, although a single sensor may be a useful aid, it is not reasonable to implant devices that do not function much better than an external sensor.…”

Section: Discussionmentioning

confidence: 99%

“…Clinical tests involving one presentation and multiple possible responses are frequently referred to as MAFC tests. 24 This term is used because MAFC tests are considered to be superior in the sense that they are free of bias. However, typical single presentation with multiple response option (MAFC) tests (such as tumbling E) are not free of bias.…”

Section: Discussionmentioning

confidence: 99%

“…However, typical single presentation with multiple response option (MAFC) tests (such as tumbling E) are not free of bias. 24 Multi interval test with multiple stimuli may not be free of bias either. 42 However, neither of these aspects are at the heart of the issue discussed here.…”

Section: Discussionmentioning

confidence: 99%

“…Bach et al 23 developed a Basic Assessment of Light and Motion system to test patients with ultra-low vision using paradigms sometimes called 2AFC or four-alternative forced-choice (4AFC). 24 They tested basic functions: light perception with an unstructured large-field; single versus double flash discrimination; localization of light in one of four possible directions; and motion in one of four directions. These were administered to people with severely impaired vision and were found to be effective in discriminating people with no light perception from those with light perception and, in some cases, from people with only “hand motion” vision.…”

Section: Mafc Testing Of Prosthetic Vision Functionmentioning

confidence: 99%

“…In addition, the subsampled images had full dynamic range (greyscale levels), whereas the E test stimuli were binary. It has been pointed out (by Bailey et al 24 ) that “The scores from any of the various visual acuity tests should not be assumed to be measures of the person's ability to perform visually guided functional tasks in everyday life.”…”

Section: Mafc Testing Of Prosthetic Vision Functionmentioning

confidence: 99%

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Testing Vision Is Not Testing For Vision

Peli

2020

Trans. Vis. Sci. Tech.

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Visual prostheses aim to restore, at least to some extent, vision that leads to the type of perception available for sighted patients. Their effectiveness is almost always evaluated using clinical tests of vision. Clinical vision tests are designed to measure the limits of parameters of a functioning visual system. I argue here that these tests are rarely suited to determine the ability of prosthetic devices and other therapies to restore vision. This paper describes and explains many limitations of these evaluations. Prosthetic vision testing often makes use of multiple-alternative forced-choice (MAFC) procedures. Although these paradigms are suitable for many studies, they are frequently problematic in vision restoration evaluation. Two main types of problems are identified: (1) where nuisance variables provide spurious cues that can be learned in repeated training, which is common in prosthetic vision, and thus defeat the purpose of the test; and (2) even though a test is properly designed and performed, it may not actually measure what the researchers believe, and thus the interpretation of results is wrong. Examples for both types of problems are presented. Additional problems arise from confounding factors in the administration of tests are pointed as limitations of current device evaluation. For example, head tracing of magnified objects enlarged to compensate for the system's low resolution, in distinction from the scanning head (camera) movements with which users of prosthetic devices expand the limited field of view. Because of these problems, the ability to perform satisfactorily on the clinical tests is necessary but insufficient to prove vision restoration, therefore, additional tests are needed. I propose some directions to pursue in such testing. Translational Relevance Numerous prosthetic devices are being developed and introduced to the market. Proving the utility of these devices is crucial for regulatory and even for post market acceptance, which so far has largely failed, in my opinion. Potential reasons for the failures despite success in regulatory testing and directions for designing improved testing are provided. It is hoped that improved testing will guide improved designs of future prosthetic systems and other vision restoration approaches.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%