• Title/Summary/Keyword: 변성망막

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Electrical Stimulation Parameters in Normal and Degenerate Rabbit Retina (정상 망막과 변성 망막을 위한 전기자극 파라미터)

  • Jin, Gye-Hwan;Goo, Yong-Sook
    • Progress in Medical Physics
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    • v.19 no.1
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    • pp.73-79
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    • 2008
  • Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa (RP) or age related macular degeneration (AMD). Recently Korean consortium launched for developing retinal prosthesis. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we performed voltage stimulation experiment both in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: $50k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. Mono-polar electrical stimulation was applied through one of the 60 MEA channel, and the remaining channels were used for recording. The electrical stimulus was a constant voltage, charge-balanced biphasic, anodic-first square wave pulse without interphase delay, and 50 trains of pulse was applied with a period of 2 sec. Different electrical stimuli were applied. First, pulse amplitude was varied (voltage: $0.5{\sim}3.0V$). Second, pulse duration was varied $(100{\sim}1,200{\mu}s)$. Evoked responses were analyzed by PSTH from averaged data with 50 trials. Charge density was calculated with Ohm's and Coulomb's law. In normal retina, by varying the pulse amplitude from 0.5 to 3V with fixed duration of $500{\mu}s$, the threshold level for reliable ganglion cell response was found at 1.5V. The calculated threshold of charge density was $2.123mC/cm^2$. By varying the pulse duration from 100 to $1,200{\mu}s$ with fixed amplitude of 2V, the threshold level was found at $300{\mu}s$. The calculated threhold of charge density was $1.698mC/cm^2$. Even after the block of ON-pathway with L-(1)-2-amino-4-phosphonobutyric acid (APB), electrical stimulus evoked ganglion cell activities. In this APB-induced degenerate retina, by varying the pulse duration from 100 to $1200{\mu}s$ with fixed voltage of 2 V, the threshold level was found at $300{\mu}s$, which is the same with normal retina. More experiment with APB-induced degenerate retina is needed to make a clear comparison of threshold of charge density between normal and degenerate retina.

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Comparison of Retinal Ganglion Cell Responses to Different Voltage Stimulation Parameters in Normal and rd1 Mouse Retina (정상망막과 변성망막에서 전압자극 파라미터 변화에 따른 망막신경절세포의 반응 비교)

  • Ye, Jang-Hee;Ryu, Sang-Baek;Kim, Kyung-Hwan;Goo, Yong-Sook
    • Progress in Medical Physics
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    • v.21 no.2
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    • pp.209-217
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    • 2010
  • Retinal prostheses are being developed to restore vision for the blind with retinal diseases such as retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Since retinal prostheses depend upon electrical stimulation to control neural activity, optimal stimulation parameters for successful encoding of visual information are one of the most important requirements to enable visual perception. Therefore, in this paper, we focused on retinal ganglion cell (RGC) responses to different voltage stimulation parameters and compared threshold charge densities in normal and rd1 mice. For this purpose, we used in vitro preparation for the retina of normal and rd1 mice on micro-electrode arrays. When the neural network of rd1 mouse retinas is stimulated with voltage-controlled pulses, RGCs in degenerated retina also respond to voltage amplitude or voltage duration modulation as well in wild-type RGCs. But the temporal pattern of RGCs response is very different; in wild-type RGCs, single peak within 100 ms appears while in RGCs in degenerated retina multiple peaks (~4 peaks) with ~10 Hz rhythm within 400 ms appear. The thresholds for electrical activation of RGCs are overall more elevated in rd1 mouse retinas compared to wild-type mouse retinas: The thresholds for activation of RGCs in rd1 mouse retinas were on average two times higher ($70.50{\sim}99.87\;{\mu}C/cm^2$ vs. $37.23{\sim}61.65\;{\mu}C/cm^2$) in the experiment of voltage amplitude modulation and five times higher ($120.5{\sim}170.6\;{\mu}C/cm^2$ vs. $22.69{\sim}37.57\;{\mu}C/cm^2$) in the experiment of voltage duration modulation than those in wild-type mouse retinas. This is compatible with the findings from human studies that the currents required for evoking visual percepts in RP patients is much higher than those needed in healthy individuals. These results will be used as a guideline for optimal stimulation parameters for upcoming Korean-type retinal prosthesis.

Spatiotemporal Analysis of Retinal Waveform using Independent Component Analysis in Normal and rd/rd Mouse (독립성분분석을 이용한 정상 마우스와 rd/rd 마우스 망막파형의 시공간적 분석)

  • Ye, Jang-Hee;Kim, Tae-Seong;Goo, Yong-Sook
    • Progress in Medical Physics
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    • v.18 no.1
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    • pp.20-26
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    • 2007
  • It is expected that synaptic construction and electrical characteristics In degenerate retina might be different from those In normal retina. Therefore, we analyzed the retinal waveform recorded with multielectrode array in normal and degenerate retina using principal component analysis (PCA) and Independent component analysis (ICA) and compared the results. PCA Is a well established method for retinal waveform while ICA has not tried for retinal waveform analysis. We programmed ICA toolbox for spatiotemporal analysis of retinal waveform. In normal mouse, the MEA spatial map shows a single hot spot perfectly matched with PCA-derived ON or OFF ganglion cell response. However In rd/rd mouse, the MEA spatial map shows numerous hot and cold spots whose underlying interactions and mechanisms need further Investigation for better understanding.

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Comparison of Retinal Waveform between Normal and rd/rd Mouse (정상 마우스와 rd/rd 마우스의 망막파형 비교)

  • Ye, Jang-Hee;Seo, Je-Hoon;Goo, Yong-Sook
    • Progress in Medical Physics
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    • v.19 no.3
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    • pp.157-163
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    • 2008
  • Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa or age-related macular degeneration. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we investigated differences of the retinal waveforms in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: 50 $k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. In normal mice (C57BL/6J strain) of postnatal day 28, only short duration (<2 ms) retinal spikes were recorded. In rd/rd mice (C3H/HeJ strain), besides normal spikes, waveform with longer duration (~100 ms), the slow wave component was recorded. We attempted to understand the mechanism of this slow wave component in degenerate retina using various synaptic blockers. We suggest that stronger glutamatergic input from bipolar cell to the ganglion cell in rd/rd mouse than normal mouse contributes the most to this slow wave component. Out of many degenerative changes, we favor elimination of the inhibitory horizontal input to bipolar cells as a main contributor for a relatively stronger input from bipolar cell to ganglion cell in rd/rd mouse.

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Pattern Classification of Retinitis Pigmentosa Data for Prediction of Prognosis (망막색소변성 데이터의 예후 예측을 위한 패턴 분류)

  • Kim, Hyun-Mi;Woo, Yong-Tae;Jung, Sung-Hwan
    • Journal of Korea Multimedia Society
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    • v.15 no.6
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    • pp.701-710
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    • 2012
  • Retinitis Pigmentosa(RP) is a common hereditary disease. While they have been normally living, those who have this symptom feel frustration and pain by the damage of visual acuity. At the national level, the loss of the economic activity due to the reduction of economically active population will be also greater. There is an urgent need for the base study that can provide the clinical prognosis information of RP disease. In this study, we suggest that it is possible to predict prognosis through the pattern classification of RP data. Statistical processing results through statistical software like SPSS(Statistical Package for the Social Service) were mainly applied for the conventional study in data analysis. However, machine learning and automatic pattern classification was applied to this study. SVM(Support Vector Machine) and other various pattern classifiers were used for it. The proposed method confirmed the possibility of prognostic prediction based on the result of automatically classified RP data by SVM classifier.

Hereditary Retinal Degeneration in a Siamese Cat (샴 고양이에서의 유전성 망막 변성 1례)

  • Park, Sang-Wan;Kang, Seon-Mi;Lee, Eui-Ri;Kim, Soo-Hyun;Noh, Hyun-Woo;Kwak, Ji-Yoon;Seo, Kangmoon
    • Journal of Veterinary Clinics
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    • v.32 no.2
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    • pp.209-211
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    • 2015
  • A 5-year-old Siamese cat was presented at the Veterinary Medical Teaching Hospital in Seoul National University with visual impairment. The cat was blind and its pupillary light reflexes were sluggish OU. While there were no remarkable findings in the anterior segment, generalized tapetal hyperreflectivity and retinal vascular attenuation were observed in the posterior segment of both eyes. Any historical significance and clinical symptoms suggestive of infection or inflammation were absent. All of the above findings strongly indicated a diagnosis of hereditary retinal degeneration in the cat. This clinical case report demonstrates the possibility of the presence of feline hereditary retinal degeneration in Korea. Awareness of the condition should be raised to prevent the spread of hereditary retinopathy in the Korean cat population.

노안과 노년기의 시력장애

  • 이재흥
    • The Korean Chronic Disease News
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    • no.94
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    • pp.6-7
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    • 1988
  • 중년 이후에는 대부분의 사람이 생리적인 노화현상의 일환으로 시력의 사용에 불편을 느끼게 되며 때로는 중년이후에 잘 발생하는 질환에 의하여, 심한 시력장애를 일으키는 수도 있다. 전자의 경우에는 노안, 비문증 등을 들 수 있고 후자의 경우는 백내장, 당뇨병성망막증, 망막정맥폐쇄증, 황반부 변성등을 들 수 있다.

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Stem Cell Based Strategies for the Treatment of Degenerative Retinal Diseases (망막변성질환에서의 줄기세포 기반치료)

  • Park, Jung-Hyun;Ku, Seung-Yup;Cho, Myung-Soo;Lee, Hak-Sup;Choi, Young-Min;Moon, Shin-Yong;Yu, Hyeong-Gon
    • Clinical and Experimental Reproductive Medicine
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    • v.37 no.3
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    • pp.199-206
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    • 2010
  • Stem-cell therapy has the potential to improve vision in patients with untreatable retinal disease. Various types of cell source including fetal, embryonic and adult stem cells, intrinsic and extrinsic factors for differentiation into retinal progenitors and transplantation mode were discussed in this review. Experimental approaches have successfully induced photoreceptor precursor cells and retinal pigment epithelium. Stem-cell-based therapy is a promising treatment to restore vision in patients with retinal disease, in spite of the challenges.

Hereditary Retinitis Pigmentosa: Report of 1 Case Treated by Oriental Medicine (유전성 망막색소변성 한방 치험 1례)

  • Jung, Hyeon-A;Hong, Seok-Hun;Roh, Sek-Seun;Kim, Chang-Hun
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.19 no.3 s.31
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    • pp.224-231
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    • 2006
  • Retinitis pigmentosa(RP) is characterized by night-blindness, contraction of the visual field, distinct hereditary nature, wide-spread pigmentary in the midperiphery. We have experienced a case of retinitis pigmentosa treated by oriental medicine (Herbal medicaiton, Acupuncture & Electroacupuncture therapy). In the point of Differentiation of syndrome, this subject was diagnosed deficiency of both Gi & blood and Eum deficiency of Liver and Kidney. So we was administrated with Palmultang-Gamibang. After treatment of orient medicine, symptoms of patient were improved.

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AMD Identification from OCT Volume Data Acquired from Heterogeneous OCT Machines using Deep Convolutional Neural Network (이종의 OCT 기기로부터 생성된 볼륨 데이터로부터 심층 컨볼루션 신경망을 이용한 AMD 진단)

  • Kwon, Oh-Heum;Jung, Yoo Jin;Kwon, Ki-Ryong;Song, Ha-Joo
    • Database Research
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    • v.34 no.3
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    • pp.124-136
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    • 2018
  • There have been active research activities to use neural networks to analyze OCT images and make medical decisions. One requirement for these approaches to be promising solutions is that the trained network must be generalized to new devices without a substantial loss of performance. In this paper, we use a deep convolutional neural network to distinguish AMD from normal patients. The network was trained using a data set generated from an OCT device. We observed a significant performance degradation when it was applied to a new data set obtained from a different OCT device. To overcome this performance degradation, we propose an image normalization method which performs segmentation of OCT images to identify the retina area and aligns images so that the retina region lies horizontally in the image. We experimentally evaluated the performance of the proposed method. The experiment confirmed a significant performance improvement of our approach.