The Experts below are selected from a list of 1977 Experts worldwide ranked by ideXlab platform
Hafsah Ahmad - One of the best experts on this subject based on the ideXlab platform.
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An audio-visual motor training improves audio spatial localization skills in individuals with Scotomas due to retinal degenerative diseases
'Elsevier BV', 2021Co-Authors: Hafsah Ahmad, Claudio Campus, Elisabetta Capris, Valentina Facchini, Giulio Sandini, Alessia Tonelli, Monica GoriAbstract:Several studies have shown that impairments in a sensory modality can induce perceptual deficits in tasks involving the remaining senses. For example, people with retinal degenerative diseases like Macular Degeneration (MD) and with Central Scotoma show biased auditory localization abilities towards the visual field's Scotoma area. This result indicates an auditory spatial reorganization of cross-modal processing in people with Scotoma when the visual information is impaired. Recent works showed that multisensory training could be beneficial to improve spatial perception. In line with this idea, here we hypothesize that audio-visual and motor training could improve people's spatial skills with retinal degenerative diseases. In the present study, we tested this hypothesis by testing two groups of Scotoma patients in an auditory and visual localization task before and after a training or rest performance. The training group was tested before and after multisensory training, while the control group performed the two tasks twice after 10 min of break. The training was done with a portable device positioned on the finger, providing spatially and temporally congruent audio and visual feedback during arm movement. Our findings show improved audio and visual localization for the training group and not for the control group. These results suggest that integrating multiple spatial sensory cues can improve the spatial perception of Scotoma patients. This finding ignites further research and applications for people with Central Scotoma for whom rehabilitation is classically focused on training visual modality only
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the sound of Scotoma audio space representation reorganization in individuals with macular degeneration
Frontiers in Integrative Neuroscience, 2019Co-Authors: Hafsah Ahmad, Walter Setti, Claudio Campus, Elisabetta Capris, Valentina Facchini, Giulio Sandini, Monica GoriAbstract:Blindness is an ideal condition to study the role of visual input on the development of spatial representation. Studies have shown how audio space representation reorganizes in blindness. However, how spatial reorganization works is still unclear. A limit of the study on blindness is that it is a “stable” system and it does not allow studying the mechanisms that subtend the progress of this reorganization. To overcome this problem here we study, for the first time, audio spatial reorganization in 18 adults with Macular Degeneration for which the loss of vision due to Scotoma is an ongoing progressive process. Our results show that the loss of vision produces immediate changes in the processing of spatial audio signals. In individuals with Macular Degeneration, the lateral sounds are “attracted” towards the Central Scotoma position resulting in a strong bias in the spatial auditory percept. This result suggests that the reorganization of audio space representation is a fast and plastic process occurring also later in life, after vision loss.
Monica Gori - One of the best experts on this subject based on the ideXlab platform.
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An audio-visual motor training improves audio spatial localization skills in individuals with Scotomas due to retinal degenerative diseases
'Elsevier BV', 2021Co-Authors: Hafsah Ahmad, Claudio Campus, Elisabetta Capris, Valentina Facchini, Giulio Sandini, Alessia Tonelli, Monica GoriAbstract:Several studies have shown that impairments in a sensory modality can induce perceptual deficits in tasks involving the remaining senses. For example, people with retinal degenerative diseases like Macular Degeneration (MD) and with Central Scotoma show biased auditory localization abilities towards the visual field's Scotoma area. This result indicates an auditory spatial reorganization of cross-modal processing in people with Scotoma when the visual information is impaired. Recent works showed that multisensory training could be beneficial to improve spatial perception. In line with this idea, here we hypothesize that audio-visual and motor training could improve people's spatial skills with retinal degenerative diseases. In the present study, we tested this hypothesis by testing two groups of Scotoma patients in an auditory and visual localization task before and after a training or rest performance. The training group was tested before and after multisensory training, while the control group performed the two tasks twice after 10 min of break. The training was done with a portable device positioned on the finger, providing spatially and temporally congruent audio and visual feedback during arm movement. Our findings show improved audio and visual localization for the training group and not for the control group. These results suggest that integrating multiple spatial sensory cues can improve the spatial perception of Scotoma patients. This finding ignites further research and applications for people with Central Scotoma for whom rehabilitation is classically focused on training visual modality only
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the sound of Scotoma audio space representation reorganization in individuals with macular degeneration
Frontiers in Integrative Neuroscience, 2019Co-Authors: Hafsah Ahmad, Walter Setti, Claudio Campus, Elisabetta Capris, Valentina Facchini, Giulio Sandini, Monica GoriAbstract:Blindness is an ideal condition to study the role of visual input on the development of spatial representation. Studies have shown how audio space representation reorganizes in blindness. However, how spatial reorganization works is still unclear. A limit of the study on blindness is that it is a “stable” system and it does not allow studying the mechanisms that subtend the progress of this reorganization. To overcome this problem here we study, for the first time, audio spatial reorganization in 18 adults with Macular Degeneration for which the loss of vision due to Scotoma is an ongoing progressive process. Our results show that the loss of vision produces immediate changes in the processing of spatial audio signals. In individuals with Macular Degeneration, the lateral sounds are “attracted” towards the Central Scotoma position resulting in a strong bias in the spatial auditory percept. This result suggests that the reorganization of audio space representation is a fast and plastic process occurring also later in life, after vision loss.
Akitoshi Yoshida - One of the best experts on this subject based on the ideXlab platform.
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association of preoperative photoreceptor displacement and improved Central Scotoma after idiopathic macular hole surgery
Ophthalmology, 2002Co-Authors: Taiichi Hikichi, Fumihiko Mori, Satoshi Ishiko, Norihiko Kitaya, J Takahashi, Akitoshi YoshidaAbstract:Abstract Objective To investigate the relationship between preoperative photoreceptor displacement and postoperative Scotoma after unilateral idiopathic macular hole surgery. Design Prospective nonrandomized comparative self-controlled trial. Participants Twenty patients who underwent successful surgery for unilateral idiopathic macular hole participated in the study. Methods Kinetic perimetry using red and green filter glasses, black binocular fixation targets, and red and green selective monocular stimuli was performed preoperatively. Scanning laser ophthalmoscope (SLO) microperimetry was performed preoperatively and postoperatively. Results Sixteen patients had photoreceptor displacement preoperatively. In preoperative SLO microperimetry, all eyes with a macular hole had a Scotoma; postoperatively, 12 of 16 had no Scotoma. All four eyes with no preoperative photoreceptor displacement were noted to have a postoperative Scotoma. The prevalence of postoperative Scotoma in patients with preoperative photoreceptor displacement (4 of 16; 25%) was significantly lower than that in patients without preoperative photoreceptor displacement (4 of 4; 100%) ( P = 0.03). Conclusions The presence or absence of photoreceptor displacement preoperatively should affect postsurgical visual function. Photoreceptor damage may occur in eyes without photoreceptor displacement preoperatively, resulting in Scotoma postoperatively.
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Scotoma and fixation patterns using scanning laser ophthalmoscope microperimetry in patients with macular dystrophy.
American Journal of Ophthalmology, 2001Co-Authors: Fumihiko Mori, Satoshi Ishiko, Norihiko Kitaya, Akira Takamiya, Eiichi Sato, Taiichi Hikichi, Akitoshi YoshidaAbstract:Abstract PURPOSE: We used scanning laser ophthalmoscope microperimetry to evaluate the retinal Scotoma and the fixation points in the patients with macular dystrophy. METHODS: We studied 10 eyes of five patients with macular dystrophy (three patients with cone dystrophy and two patients with Stargardt disease). The mean patient age was 37 years (range, 13 to 64 years). An estimation of Scotoma and fixation points on the retina was performed using scanning laser ophthalmoscope microperimetry. RESULTS: All 10 eyes (100%) had one of two types of dense Scotoma: type one was a dense ring Scotoma (five eyes, 50%), and type two was a dense Central Scotoma (five eyes, 50%) that included the center of the fovea. In all eyes with a dense ring Scotoma, the fixation points were stable and did not shift. In all eyes with a dense Central Scotoma, the fixation shifted. The logarithm of minimal angle of resolution of the visual acuity in the eyes with the dense Central Scotoma was significantly worse than that of eyes with the dense ring Scotoma type ( P = .005). CONCLUSIONS: Scanning laser ophthalmoscope microperimetry findings demonstrate two types of dense Scotoma (dense ring Scotoma and dense Central Scotoma) in the patients with macular dystrophy. The two types of dense Scotoma affect the shifting of the fixation points and the stability of fixation and may result in the difference in visual acuity in the patients with macular dystrophy.
Robert Rejdak - One of the best experts on this subject based on the ideXlab platform.
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visual rehabilitation training in a patient with large Central Scotoma due to leber s hereditary optic neuropathy
Ophthalmology, 2018Co-Authors: Agnieszka Kiszka, Dominika Nowakowska, Katarzyna Nowomiejska, Katarzyna Tonska, Robert RejdakAbstract:Background. Leber’s hereditary optic neuropathy (LHON) is a disease associated with pathogenetic mutations of mitochondrial DNA which affects predominantly young adult males and leads to loss of Central vision, low visual acuity and unstable fixation. The purpose of this study was to allow the patient to establish the best possible fixation in the best area of retinal sensitivity in LHON patient with Central Scotoma. Methods. A 17 years old patient with confirmed mitochondrial LHON 11778G > A mutation was included in the study. The patient underwent 16 visual rehabilitation sessions — two for each of 8 weeks using the training module available in the equipment — MAIA microperimeter. Visual acuity and standrad microperimetry examination were performed before and 8 weeks period of training. To measure the fixation stability with MAIA microperimeter, P1, P2 and Bivariate Contour Ellipse Area (BCEA) parameters were used. Results. Visual acuity of the trained better eye was 0.08 at the baseline versus 0.063 after 8 weeks training. Fixation stability parameter was P1-21%, P2-64% at the first session versus P1-60%, P2-90% at the last session. BCEA values 29.2°˛ before and 14.2°˛ after training, respectively. Conclusions. Visual training via microperimetry could potentially be a method that improves the fixation stability in patients with LHON.
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Analysis of Visual Field Defects Obtained with Semiautomated Kinetic Perimetry in Patients with Leber Hereditary Optic Neuropathy
Hindawi Limited, 2018Co-Authors: Katarzyna Nowomiejska, Agnieszka Kiszka, Katarzyna Tonska, Edyta Koman-wierdak, Ryszard Maciejewski, Anselm G. Jünemann, Robert RejdakAbstract:Purpose. To analyse visual field (VF) defects obtained using semiautomated kinetic perimetry (SKP) in patients suffering from Leber hereditary optic neuropathy (LHON). Methods. Twenty-two eyes of eleven consecutive LHON male patients with confirmed mitochondrial 11778G>A DNA mutation were prospectively examined with the V4e stimulus of SKP in both eyes. The mean time after the onset of LHON was one year. The area of obtained isopters was measured in square degrees (deg2). Additionally, static automated perimetry (SAP) within 30° was performed. Results. Visual acuity ranged from counting fingers to 50 cm to 0.4. VFs obtained with SKP showed Central Scotomas in 18 eyes (82%); the periphery of the VF in these eyes remained intact. The mean area of Central Scotoma was 408.8 deg2, and the mean area of the peripheral VF was 12291.1 deg2; SAP also revealed Central Scotoma in these patients. In four eyes (18%) with the worst visual acuity, only the residual Central island of VF was found using SKP (mean area 898.4 deg2). SAP was difficult to obtain in these patients. Conclusions. SKP provides additional clinical information in regard to the visual function of LHON patients. SKP enables the quantification of the area of Central Scotoma, preserved peripheral VF, and residual Central island of vision. Using V4 stimulus is especially useful in LHON patients with poor visual acuity, when SAP is difficult to obtain
Tatsuo Hirose - One of the best experts on this subject based on the ideXlab platform.
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effects of light scatter defocusing mean luminosity contrast and Central Scotoma on the pver amplitude check size function curve
Acta Ophthalmologica, 2009Co-Authors: Osamu Katsumi, Hitomi Tetsuka, Soichi Tetsuka, Young Hoonohn, Tatsuo HiroseAbstract:. We analyzed the effects of various stimulus parameters, ie, light scatter, defocusing, mean luminosity, contrast, and Central Scotoma, on the normal pattern reversal visual evoked response (PVER), amplitudecheck size function curve in six normal subjects. The steady-state PVER was recorded with five check sizes ranging from 160 to 10 min in 1-octave increments. The PVER amplitude, especially with the smaller check sizes, was markedly decreased by light scatter induced by acrylic sheets. The function curve quickly changed to a low pass filter shape when +2.0 diopters of defocus were added, with the decrease most marked in the small check sizes. When the mean luminosity was decreased, the function curve maintained its normal inverted-U shape up to 5 cd/m2, but the shape flattened with lower luminosity. Amplitude decreases were seen with all check sizes in low luminosity. With contrast changes from 95 to 24%, the function curve maintained its normal shape, but with slightly reduced amplitudes. The amplitude decrease was moderate even with the lowest contrast. With a two-degree Central Scotoma, the PVER amplitude was reduced more with the smaller than the larger check sizes. The function curve became somewhat flatter, with its peak shifting to the larger check sizes. Results indicated that the shape of the PVER amplitude-check size function curve changes in response to different modes of stimulation.
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evaluation of macular abnormalities in stargardt s disease using optical coherence tomography and scanning laser ophthalmoscope microperimetry
Graefes Archive for Clinical and Experimental Ophthalmology, 2009Co-Authors: Fatmire Berisha, Gilbert T Feke, Shakhsanam Aliyeva, Koji Hirai, Norbert Pfeiffer, Tatsuo HiroseAbstract:The purpose of this study is to evaluate the diagnostic value of optical coherence tomography (Stratus OCT) and scanning laser ophthalmoscope (SLO) microperimetry in patients with Stargardt’s disease (STGD), and the correlation between macular morphology and visual function in these patients. Twenty-two patients with STGD (mean age 44 years, range 11 to 71 years) and 20 age-matched healthy control subjects were included in the study. OCT imaging was performed using six radial line scans manually centered on the fovea. SLO microperimetry was used to assess Central Scotoma and fixation behavior in patients with STGD. Mean best corrected Snellen visual acuity (BCVA) was 20/80, range 20/25 to 20/300 (log MAR 0.6, range 0.1 to 1.2) in the STGD group and 20/20 (log MAR 0.0) in the control group. Foveal thickness was significantly reduced in patients with STGD (119.0 ± 19.6 μm) compared to controls (210.7 ± 19.6 μm, P < 0.0001). A significant correlation between foveal thickness and BCVA was observed within the STGD group (R2 = 0.62, P < 0.0001). Photoreceptor loss in the macular area and a corresponding Central Scotoma were observed in all STGD patients. OCT findings, particularly reduced foveomacular thickness and photoreceptor loss in the macular area may be useful in the diagnosis of STGD. Furthermore, a strong correlation between foveal thickness and visual function was observed in our patients. Assessment of Central visual function using SLO microperimetry provides additional useful information, important in the management of STGD.