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Akira Negi - One of the best experts on this subject based on the ideXlab platform.

  • quantification of retinal nerve fiber layer thickness reduction associated with a relative Afferent Pupillary Defect in asymmetric glaucoma
    2007
    Co-Authors: Yasuko Tatsumi, Makoto Nakamura, Miyuki Fujioka, Yoriko Nakanishi, Azusa Kusuhara, Hidetaka Maeda, Akira Negi
    Abstract:

    Aim: The relative Afferent Pupillary Defect (RAPD) is an important clinical sign of asymmetrical retinal ganglion cell and axonal damage. Although glaucoma essentially affects bilateral eyes, a subset of patients manifests asymmetrical glaucomatous optic neuropathy (GON), which exhibits an RPAD in the more advanced eyes. However, the degree to which axonal loss occurs before an RAPD is clinically detectable has not been substantiated. The purpose of this study is to assess the relationship between the depth of a clinically detectable RAPD and the reduction ratio of retinal nerve fiber layer (RNFL) thickness in the more advanced eyes relative to that in the contralateral less advanced eyes of patients with asymmetrical GON. Methods: Enrolled were 29 consecutive glaucoma patients with the clinically detectable RAPD. An RAPD was quantified by placing log-scaled neutral density filters over the less advanced eyes while performing the swinging flashlight test. Average RNFL thickness was determined using the Fast RNFL thickness programme of optical coherence tomography 3000. Correlation coefficient and Linear regression analyses were used in assessing the relationship between the RAPD and the ratio of RNFL thickness in the more advanced eyes relative to that in the less advanced. Results: RAPD ranged from 0.6 to 2.4 log units. The log-scaled RAPD had a statistically significantly inversed correlation with the average RNFL thickness ratio (r s  = −0.729, p 2  = 0.557, p Conclusions: When an RAPD is clinically detected, the RNFL thickness in the more advanced eyes was in average reduced to about 73% of that in the less advanced.

  • quantification of retinal nerve fiber layer thickness reduction associated with a relative Afferent Pupillary Defect
    2006
    Co-Authors: Yoriko Nakanishi, Yasuko Tatsumi, Makoto Nakamura, Azusa Nagaikusuhara, Akira Negi
    Abstract:

    A relative Afferent Pupillary Defect (RAPD) is known to develop only when more than 25% of retinal ganglion cells are ablated in monkeys’ eyes. However, there was no prior study to estimate biometrically the degree of retinal nerve fiber layer (RNFL) thickness reduction leading to the development of RAPD in live human eyes. The purpose of this study was to examine the correlation between the amount of RNFL thickness reduction and the depth of a clinically detectable RAPD in patients with unilateral optic atrophy. Enrolled were 20 patients with optic atrophy of various etiologies. We quantified RAPD by performing the swinging flashlight test with log-scaled neutral density filters placed over the unaffected eye. Average RNFL thickness was measured by OCT3000 with the average RNFL thickness program. Linear regression analysis was used in assessing the relationship between RAPD and the ratio of affected to unaffected average RNFL thickness. The mean of average RNFL thickness was 95.6±17.3 μm in the unaffected eyes and 50.7±19.3 μm in the affected eyes (P<0.001). Regression analysis between RAPD and the ratio of affected to unaffected average RNFL thickness revealed a correlation coefficient R2=0.48 (P=0.0007). The regression line intersected the y-axis at 0.77. RAPD was not clinically detected until at least approximately 25% of the retinal nerve fibers were lost when compared with the unaffected eyes. Substantial retinal ganglion cell damage is required for the development of RAPD.

Yoriko Nakanishi - One of the best experts on this subject based on the ideXlab platform.

  • quantification of retinal nerve fiber layer thickness reduction associated with a relative Afferent Pupillary Defect in asymmetric glaucoma
    2007
    Co-Authors: Yasuko Tatsumi, Makoto Nakamura, Miyuki Fujioka, Yoriko Nakanishi, Azusa Kusuhara, Hidetaka Maeda, Akira Negi
    Abstract:

    Aim: The relative Afferent Pupillary Defect (RAPD) is an important clinical sign of asymmetrical retinal ganglion cell and axonal damage. Although glaucoma essentially affects bilateral eyes, a subset of patients manifests asymmetrical glaucomatous optic neuropathy (GON), which exhibits an RPAD in the more advanced eyes. However, the degree to which axonal loss occurs before an RAPD is clinically detectable has not been substantiated. The purpose of this study is to assess the relationship between the depth of a clinically detectable RAPD and the reduction ratio of retinal nerve fiber layer (RNFL) thickness in the more advanced eyes relative to that in the contralateral less advanced eyes of patients with asymmetrical GON. Methods: Enrolled were 29 consecutive glaucoma patients with the clinically detectable RAPD. An RAPD was quantified by placing log-scaled neutral density filters over the less advanced eyes while performing the swinging flashlight test. Average RNFL thickness was determined using the Fast RNFL thickness programme of optical coherence tomography 3000. Correlation coefficient and Linear regression analyses were used in assessing the relationship between the RAPD and the ratio of RNFL thickness in the more advanced eyes relative to that in the less advanced. Results: RAPD ranged from 0.6 to 2.4 log units. The log-scaled RAPD had a statistically significantly inversed correlation with the average RNFL thickness ratio (r s  = −0.729, p 2  = 0.557, p Conclusions: When an RAPD is clinically detected, the RNFL thickness in the more advanced eyes was in average reduced to about 73% of that in the less advanced.

  • quantification of retinal nerve fiber layer thickness reduction associated with a relative Afferent Pupillary Defect
    2006
    Co-Authors: Yoriko Nakanishi, Yasuko Tatsumi, Makoto Nakamura, Azusa Nagaikusuhara, Akira Negi
    Abstract:

    A relative Afferent Pupillary Defect (RAPD) is known to develop only when more than 25% of retinal ganglion cells are ablated in monkeys’ eyes. However, there was no prior study to estimate biometrically the degree of retinal nerve fiber layer (RNFL) thickness reduction leading to the development of RAPD in live human eyes. The purpose of this study was to examine the correlation between the amount of RNFL thickness reduction and the depth of a clinically detectable RAPD in patients with unilateral optic atrophy. Enrolled were 20 patients with optic atrophy of various etiologies. We quantified RAPD by performing the swinging flashlight test with log-scaled neutral density filters placed over the unaffected eye. Average RNFL thickness was measured by OCT3000 with the average RNFL thickness program. Linear regression analysis was used in assessing the relationship between RAPD and the ratio of affected to unaffected average RNFL thickness. The mean of average RNFL thickness was 95.6±17.3 μm in the unaffected eyes and 50.7±19.3 μm in the affected eyes (P<0.001). Regression analysis between RAPD and the ratio of affected to unaffected average RNFL thickness revealed a correlation coefficient R2=0.48 (P=0.0007). The regression line intersected the y-axis at 0.77. RAPD was not clinically detected until at least approximately 25% of the retinal nerve fibers were lost when compared with the unaffected eyes. Substantial retinal ganglion cell damage is required for the development of RAPD.

Randy H. Kardon - One of the best experts on this subject based on the ideXlab platform.

  • pupillographic investigation of the relative Afferent Pupillary Defect associated with a midbrain lesion
    2010
    Co-Authors: Aki Kawasaki, Neil R Miller, Randy H. Kardon
    Abstract:

    Objective To identify clinical and pupillographic features of patients with a relative Afferent Pupillary Defect (RAPD) without visual acuity or visual field loss caused by a lesion in the dorsal midbrain. Design Experimental study. Participants and Controls Four patients with a dorsal midbrain lesion who had normal visual fields and a clinically detectable RAPD. Methods The pupil response from full-field and hemifield light stimulation over a range of light intensities was measured by computerized binocular pupillography. Main Outcome Measures The mean of the direct and consensual pupil response to full-field and hemifield light stimulation was plotted as a function of stimulus light intensity. Results All 4 subjects showed decreased pupillographic responses at all intensities to full-field light stimulation in the eye with the clinical RAPD. The pupillographic responses to hemifield stimulation showed a homonymous pattern of deficit on the side ipsilateral to the RAPD, similar to that observed in a previously reported patient with an optic tract lesion. Conclusions The basis of a midbrain RAPD is the nasal-temporal asymmetry of pupillomotor input that becomes manifest when a unilateral postchiasmal lesion interrupts homonymously paired fibers traveling in the contralateral optic tract or midbrain pathway to the pupillomotor center, respectively. The pupillographic characteristics of an RAPD resulting from a dorsal midbrain lesion thus resemble those of an RAPD resulting from a unilateral optic tract lesion, but without the homonymous visual field Defect. Financial Disclosure(s) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

  • origin of the relative Afferent Pupillary Defect in optic tract lesions
    2006
    Co-Authors: Randy H. Kardon, Aki Kawasaki, Neil R Miller
    Abstract:

    Objective To determine the percent decussation of pupil input fibers in humans and to explain the size and range of the log unit relative Afferent Pupillary Defect (RAPD) in patients with optic tract lesions. Design Experimental study. Participants and Controls Five patients with a unilateral optic tract lesion. Methods The pupil response from light stimulation of the nasal hemifield, temporal hemifield, and full field of each eye of 5 patients with a unilateral optic tract lesion was recorded using computerized binocular infrared pupillography. Six stimulus light intensities, separated by 0.5–log unit steps, were used; 12 stimulus repetitions were given for each stimulus condition. Main Outcome Measures For each stimulus condition, the pupil response of each eye was characterized by plotting the mean pupil contraction amplitude as a function of stimulus light intensity. The percentage of decussating Afferent pupillomotor input fibers was calculated from the ratio of the maximal pupil contractions elicited from each eye. The RAPD was determined pupillographically from full-field stimulation to each eye. Results In all patients, the pupil response from the functioning temporal hemifield ipsilateral to the tract lesion was greater than that from the functioning contralateral nasal hemifield. This temporal–nasal asymmetry increased with increasing stimulus intensity and was similar in hemifield and full-field stimuli, eventually saturating at maximal light intensity. The log unit RAPD did not correlate with the estimated percentage of decussating pupil fibers, which ranged from 54% to 67%. Conclusions In patients with a unilateral optic tract lesion, the Pupillary responses from full-field stimulation to each eye are the same as comparing the functioning temporal field with the functioning nasal field. The percentage of decussating fibers is reflected in the ratio of the maximal pupil contraction amplitudes resulting from stimulus input between the two eyes. The RAPD that occurs in this setting reflects the difference in light sensitivity between the intact temporal and nasal hemifields. Its magnitude does not correlate with the difference in the number of crossed and uncrossed axons, but its sidedness contralateral to the side of the optic tract lesion is consistent with the greater percentage of decussating pupillomotor input.

  • long term fluctuation of relative Afferent Pupillary Defect in subjects with normal visual function
    1996
    Co-Authors: Aki Kawasaki, Paula Moore, Randy H. Kardon
    Abstract:

    Purpose To determine whether the relative Afferent Pupillary Defect (RAPD) remains constant over time in normal subjects. Methods Seventeen normal subjects were tested with infrared pupillography and automated perimetry in four sessions over 3 years. The changes in RAPD and visual field asymmetry between testing sessions were compared. Results The range of RAPD was 0.0 to 0.3 log unit, and the difference in the mean deviation between the eyes on automated static perimetry was 0 to 3 dB. Eight subjects repeatedly had an RAPD in the same eye. There was no correlation between the RAPD and the visual field asymmetry at the same visit. Changes in the magnitude of the RAPD between any two sessions were typically small (median, 0.08 log unit; 25th percentile, 0.04 log unit; 75th percentile, 0.15 log unit). Conclusions Some normal subjects may show a persistent but small RAPD in the absence of detectable pathologic disease. Therefore, an isolated RAPD in the range of 0.3 log unit that is not associated with any other significant historical or clinical finding should probably be considered benign.

  • Variability of the Relative Afferent Pupillary Defect
    1995
    Co-Authors: Aki Kawasaki, Paula A. Moore, Randy H. Kardon
    Abstract:

    Purpose Afferent asymmetry of visual function is detectable in both normal and pathologic conditions. With a computerized test, we assessed the variability in measuring Afferent asymmetry of the Pupillary light reflex, that is, the relative Afferent Pupillary Defect. Methods In ten normal subjects, Pupillary responses to an alternating light stimulus were recorded with computerized infrared pupillography. The relative Afferent Pupillary Defect for each test was determined by using a new computer analysis. The 95% confidence interval of each determination of relative Afferent Pupillary Defect was used to represent the short-term fluctuation in its measurement. To optimize the test for clinical use, we studied the influence of stimulus intensity, duration, and number on the variability of the relative Afferent Pupillary Defect. Results When the relative Afferent Pupillary Defect was based on only a few light alternations (stimulus pairs), there was excessive variability in its measurement (95% confidence interval > 0.5 log units). With approximately 200 stimulus pairs, the 95% confidence interval was reduced to less than 0.1 log unit (relative Afferent Pupillary Defect ±0.05 log unit). Also, there was less variability when the dark interval between alternating light stimulation was less than one second. Conclusions Computerized infrared pupillography can standardize the alternating light test and minimize the error in quantifying a relative Afferent Pupillary Defect. A reproducible relative Afferent Pupillary Defect measurement is desirable for defining Afferent injury and following the course of disease.

  • the relationship between static perimetry and the relative Afferent Pupillary Defect
    1993
    Co-Authors: Randy H. Kardon, Christopher L Haupert, Stanley H Thompson
    Abstract:

    This study was undertaken to understand better how damage to the anterior visual pathway may affect the relationship between the visual and pupillomotor systems. The relative Afferent Pupillary Defect and the interocular difference in visual field mean deviation (determined by the Humphrey Field Analyzer Statpac program) were correlated in 137 patients. A moderate linear correlation (r = .66) was found. In 25 patients tested by both static and kinetic perimetry, the correlation could not be significantly improved by considering field loss outside of 30 degrees. The correlation was further studied in four subcategories of diagnosis: optic neuritis (n = 36), idiopathic intracranial hypertension (n = 26), compressive optic neuropathy (n = 14), and anterior ischemic optic neuropathy (n = 7). In compressive optic neuropathy and idiopathic intracranial hypertension, the difference in mean deviation between the two eyes was associated with a larger relative Afferent Pupillary Defect than in optic neuritis and anterior ischemic optic neuropathy. In optic neuritis, the correlation was the poorest. These results indicate that diseases of the Afferent visual system may not necessarily affect visual threshold (as tested by static perimetry) and the Pupillary light reflex (a suprathreshold test) in the same way.

Yasuko Tatsumi - One of the best experts on this subject based on the ideXlab platform.

  • quantification of retinal nerve fiber layer thickness reduction associated with a relative Afferent Pupillary Defect in asymmetric glaucoma
    2007
    Co-Authors: Yasuko Tatsumi, Makoto Nakamura, Miyuki Fujioka, Yoriko Nakanishi, Azusa Kusuhara, Hidetaka Maeda, Akira Negi
    Abstract:

    Aim: The relative Afferent Pupillary Defect (RAPD) is an important clinical sign of asymmetrical retinal ganglion cell and axonal damage. Although glaucoma essentially affects bilateral eyes, a subset of patients manifests asymmetrical glaucomatous optic neuropathy (GON), which exhibits an RPAD in the more advanced eyes. However, the degree to which axonal loss occurs before an RAPD is clinically detectable has not been substantiated. The purpose of this study is to assess the relationship between the depth of a clinically detectable RAPD and the reduction ratio of retinal nerve fiber layer (RNFL) thickness in the more advanced eyes relative to that in the contralateral less advanced eyes of patients with asymmetrical GON. Methods: Enrolled were 29 consecutive glaucoma patients with the clinically detectable RAPD. An RAPD was quantified by placing log-scaled neutral density filters over the less advanced eyes while performing the swinging flashlight test. Average RNFL thickness was determined using the Fast RNFL thickness programme of optical coherence tomography 3000. Correlation coefficient and Linear regression analyses were used in assessing the relationship between the RAPD and the ratio of RNFL thickness in the more advanced eyes relative to that in the less advanced. Results: RAPD ranged from 0.6 to 2.4 log units. The log-scaled RAPD had a statistically significantly inversed correlation with the average RNFL thickness ratio (r s  = −0.729, p 2  = 0.557, p Conclusions: When an RAPD is clinically detected, the RNFL thickness in the more advanced eyes was in average reduced to about 73% of that in the less advanced.

  • quantification of retinal nerve fiber layer thickness reduction associated with a relative Afferent Pupillary Defect
    2006
    Co-Authors: Yoriko Nakanishi, Yasuko Tatsumi, Makoto Nakamura, Azusa Nagaikusuhara, Akira Negi
    Abstract:

    A relative Afferent Pupillary Defect (RAPD) is known to develop only when more than 25% of retinal ganglion cells are ablated in monkeys’ eyes. However, there was no prior study to estimate biometrically the degree of retinal nerve fiber layer (RNFL) thickness reduction leading to the development of RAPD in live human eyes. The purpose of this study was to examine the correlation between the amount of RNFL thickness reduction and the depth of a clinically detectable RAPD in patients with unilateral optic atrophy. Enrolled were 20 patients with optic atrophy of various etiologies. We quantified RAPD by performing the swinging flashlight test with log-scaled neutral density filters placed over the unaffected eye. Average RNFL thickness was measured by OCT3000 with the average RNFL thickness program. Linear regression analysis was used in assessing the relationship between RAPD and the ratio of affected to unaffected average RNFL thickness. The mean of average RNFL thickness was 95.6±17.3 μm in the unaffected eyes and 50.7±19.3 μm in the affected eyes (P<0.001). Regression analysis between RAPD and the ratio of affected to unaffected average RNFL thickness revealed a correlation coefficient R2=0.48 (P=0.0007). The regression line intersected the y-axis at 0.77. RAPD was not clinically detected until at least approximately 25% of the retinal nerve fibers were lost when compared with the unaffected eyes. Substantial retinal ganglion cell damage is required for the development of RAPD.

Hal Bohlman - One of the best experts on this subject based on the ideXlab platform.

  • Afferent Pupillary Defect associated with optic nerve head drusen
    2000
    Co-Authors: Hal Bohlman
    Abstract:

    Background Optic nerve head drusen (ONHD) are a relatively uncommon finding with an estimated prevalence of anywhere from 0.3% to 2%. Reports of relative Afferent Pupillary Defects (RAPDs) associated with ONHD are scarce. Case report A patient with an RAPD was found to have ONHD as the only apparent etiology of the RAPD. The various diagnostic tests relevant to the case, the differential diagnosis, and the pathological features of ONHD are discussed. Conclusions It is important for the clinician to consider an RAPD as a possible pathological feature of ONHD--especially with an asymmetric presentation.

  • clinical care Afferent Pupillary Defect associated with optic nerve head drusen
    2000
    Co-Authors: Hal Bohlman
    Abstract:

    Background: Optic nerve head drusen (ONHD) are a relatively uncommon finding with an estimated prevalence of anywhere from 0.3% to 2%. Reports of relative Afferent Pupillary Defects (RAPDs) associated with ONHD are scarce. Case Report A patient with an RAPD was found to have ONHD as the only apparent etiology of the RAPD. The various diagnostic tests relevant to the case, the differential diagnosis, and the pathological features of ONHD are discussed. Conclusions: It is important for the clinician to consider an RAPD as a possible pathological feature of ONHD-especially with an asymmetric presentation.