Evaluation of patient suitability for a retinal prosthesis using structural and functional tests of inner retinal integrity

Huang, Qiuhen; Chowdhury, Vivek; Coroneo, Minas T.

doi:10.1088/1741-2560/6/3/035010

Cited by 11 publications

(15 citation statements)

References 18 publications

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“…Although based only on this one case, we assume that a visible layering of the inner retina in a high‐resolution OCT is a good marker for its functionality. A correlation between electrical excitability of the inner retina and its thickness has been described by other research groups …”

Section: Methodssupporting

confidence: 55%

Safety and efficacy of subretinal visual implants in humans: methodological aspects

Štingl

Bach

Bartz-Schmidt

et al. 2013

Clinical and Experimental Optometry

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Background Replacing the function of visual pathway neurons by electronic implants is a novel approach presently explored by various groups in basic research and clinical trials. The novelty raises unexplored methodological aspects of clinical trial design that may require adaptation and validation. Methods We present procedures of efficacy and safety testing for subretinal visual implants in humans, as developed during our pilot trial 2005 to 2009 and multi‐centre clinical trial since 2010. Results Planning such a trial requires appropriate inclusion and exclusion criteria. For subretinal electronic visual implants, patients with photoreceptor degeneration are the target patient group, whereas presence of additional diseases affecting clear optic media or the visual pathway must be excluded. Because sham surgery is not possible, a masked study design with implant power ON versus OFF is necessary. Prior to the efficacy testing by psychophysical tests, the implant's technical characteristics have to be controlled via electroretinography (ERG). Moreover the testing methods require adaptation to the particular technology. We recommend standardised tasks first to determine the light perception thresholds, light localisation and movement detection, followed by grating acuity and vision acuity test via Landolt C rings. A laboratory setup for assessing essential activities of daily living is presented. Subjective visual experiences with the implant in a natural environment, as well as questionnaires and psychological counselling are further important aspects. Conclusions A clinical trial protocol for artificial vision in humans, which leads a patient from blindness to the state of very low vision is a challenge and cannot be defined completely prior to the study. Available tests of visual function may not be sufficiently suited for efficacy testing of artificial vision devices. A protocol based on experience with subretinal visual implants in 22 patients is presented that has been found adequate to monitor safety and efficacy.

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Section: Methodssupporting

confidence: 55%

Safety and efficacy of subretinal visual implants in humans: methodological aspects

Štingl

Bach

Bartz-Schmidt

et al. 2013

Clinical and Experimental Optometry

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“…Huang et al [15] investigated the relative inner retinal preservation in vivo in the peripheral retina and the macula using tdOCT in patients with RP. There was a 7.39% increase in the inner retinal layer thickness in the periphery in comparison with normal controls.…”

Section: Discussionmentioning

confidence: 99%

Retinal Nerve Fiber Layer Analysis with Scanning Laser Polarimetry and RTVue-OCT in Patients of Retinitis Pigmentosa

et al. 2012

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Purpose: To measure the thickness of the retinal nerve fiber layer (RNFL) of patients with retinitis pigmentosa (RP) and that of normal controls by scanning laser polarimetry with enhanced corneal compensation (GDxECC) and RTVue-optical coherence tomography (OCT). Methods: Fifty-two eyes of 26 patients were included. All patients underwent complete ophthalmological examinations and testing with GDxECC. Twenty-eight of 52 eyes of RP patients underwent RTVue-OCT measurements. A group of 50 eyes of 25 normal subjects (controls) was also included. GDxECC measured RNFL thickness in the peripapillary area in all subjects as well as temporal-superior-nasal-inferior-temporal (TSNIT) parameters, including TSNIT means, superior and inferior region means, TSNIT standard deviation (SD), inter-eye symmetry and nerve fiber indicator (NFI). RTVue-OCT measured the mean, superior, inferior, temporal and nasal quadrant RNFL thickness. Result: In RP patients and controls, TSNIT means by GDxECC were, respectively, 65.00 ± 7.35 and 55.32 ± 5.20. Mean superior quadrant thicknesses were80.56 ± 10.93 and 69.54 ± 7.45. Mean inferior thicknesses were 80.58 ± 9.34 and 69.12 ± 7.78. SDs were 27.92 ± 5.21 and 28.23 ± 4.01. Inter-eye symmetries were 0.82 ± 0.17 and 0.87 ± 0.09. NFIs were 9.74 ± 8.73 and 16.81 ± 8.13. The differences between mean TSNIT, mean superior and mean inferior quadrant thicknesses and NFIs were statistically significant (p < 0.001). In RTVue-OCT measurements, the differences between mean, superior, inferior and temporal quadrant RNFL thicknesses were statistically significant (p = 0.0322, 0.0213, 0.0387, 0.0005). Conclusions: The RNFL measured by GDxECC was significantly thicker in RP patients than in controls. RNFL thickness measured by RTVue-OCT was significantly greater in RP patients than in controls in the superior, inferior and temporal regions. This contribution provides information on RNFL thickness and discusses the mechanism underlying this phenomenon.

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“…5 If the status of inner retina varies in each patient, selection of patients based on the preservation of inner retinal structures and functions would be helpful to achieve maximal effect from the treatments. 6 Histology studies concerning the status of the inner retina in RP are limited. [7][8][9][10] These histologic reports showed that up to 75% of ganglion cell layer cells are retained in the macular area in patients with RP; 7,8 however, the percentage decreases to 20-30% in extra-macular region 9 and 70-90% of total ganglion cells or their axons are lost eventually, 10 suggesting that inner retinal cells are partially preserved in RP, but degenerate as the disease progresses.…”

Section: Introductionmentioning

confidence: 99%

Longitudinal analysis of the peripapillary retinal nerve fiber layer thinning in patients with retinitis pigmentosa

Oishi

Ogino

Nakagawa

et al. 2013

Eye

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Purpose To investigate longitudinal changes in peripapillary retinal nerve fiber layer (RNFL) thickness in patients with retinitis pigmentosa (RP). Methods We re-examined 103 RP patients whose RNFL thickness was previously examined and reported. RNFL thickness was measured using Stratus optical coherence tomography and was compared with the previous measurements. The results were also compared with that of previously reported normal subjects. Association between the decrease rate and visual acuity, and visual field was also investigated. Results The mean follow-up period was 56.9 months. After excluding the patients in whom RNFL images were of poor quality, 88 patients were eventually analyzed. The average RNFL thickness decreased from 105.8 to 98.2 mm during the period, with the average rate of decrease being 1.6 mm/year. The decrease in RNFL was more evident in superior and inferior sectors. Cross-sectional linear regression analysis also revealed an age-dependent decrease in RNFL, with the slower rate of decrease being 0.94 mm/year. The decrease in RNFL thickness was significantly faster than that reported in normal subjects. The decrease rate was not associated with visual functions. Conclusion Age-dependent RNFL thinning occurs at a faster rate in RP patients as compared with that in normal subjects. The result supports the notion that pathologic changes involve inner retina as well as outer retina in eyes with RP. Considering the discrepancy in the rate of RNFL thinning estimated from trend analysis and longitudinal measurement, care should be taken when interpreting the result of cross-sectional analysis.

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Evaluation of patient suitability for a retinal prosthesis using structural and functional tests of inner retinal integrity

Cited by 11 publications

References 18 publications

Safety and efficacy of subretinal visual implants in humans: methodological aspects

Safety and efficacy of subretinal visual implants in humans: methodological aspects

Retinal Nerve Fiber Layer Analysis with Scanning Laser Polarimetry and RTVue-OCT in Patients of Retinitis Pigmentosa

Longitudinal analysis of the peripapillary retinal nerve fiber layer thinning in patients with retinitis pigmentosa

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