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Janet S. Sunness - One of the best experts on this subject based on the ideXlab platform.
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MAPPING THE DENSE Scotoma AND ITS ENLARGEMENT IN STARGARDT DISEASE.
Retina-the Journal of Retinal and Vitreous Diseases, 2016Co-Authors: Aryeh Bernstein, Carol A. Applegate, Janet S. Sunness, Elizabeth O. TeginsAbstract:PURPOSE: To describe the enlargement of the dense Scotoma over time in Stargardt disease and to highlight methodologic issues in tracking enlargement. METHODS: Retrospective study of patients with full mapping of the border of the dense Scotoma using the MP-1 for at least two visits. RESULTS: 14 eyes of 7 patients met this criterion. Patients had median of 3 visits (range 2-5), with median total follow-up of 4.5 years (range 1.5-8). Mean baseline visual acuity was 20/56 (range 20/25-20/200), mean baseline dense Scotoma area was 2.23 mm (range 0.41-5.48), and mean dense Scotoma enlargement rate was 1.36 mm/year (range 0.22-2.91). The younger patients tended to have more rapid loss of visual acuity, which tended to plateau when the visual acuity was 20/100 or worse. The patients who developed Stargardt before age 20 years, and the single patient who developed Stargardt disease after age 40 years, had more rapid enlargement rates, with preservation of central vision in the oldest patient. The ability to precisely define the dense Scotoma area was dependent on the density location of the points tested; this led to significant variability in the assessment of the Scotoma enlargement rate in three of the seven patients. The dense Scotoma was not described adequately by the extent of the homogeneous dark area on fundus autofluorescence imaging. CONCLUSION: Microperimetry is necessary for mapping the Scotoma in patients with Stargardt disease, because current imaging is not adequate. Standardized grid testing, plus a standardized procedure for refining the border of the dense Scotoma, should allow more precise testing and longitudinal assessment of enlargement rates.
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Retinal function and loss of autofluorescence in stargardt disease.
Retina-the Journal of Retinal and Vitreous Diseases, 2008Co-Authors: Janet S. Sunness, Joshua N. SteinerAbstract:OBJECTIVE: To determine the relationship between reduced retinal autofluorescence and the dense Scotomas in Stargardt disease. METHOD: Retrospective review of patients with Stargardt disease seen between 2000 and 2004 at a tertiary referral center. PATIENTS: All 32 patients with Stargardt who underwent both autofluorescence (AF) imaging and Scotoma mapping were included. RESULTS: Forty-seven percent of eyes had dense Scotomas corresponding to the areas of loss of AF (27% corresponding to the area of uniform loss of AF, and 20% corresponding to the area of uniform plus mottled loss of AF). Fifty-three percent of eyes did not have a good correlation of the dense Scotoma with the area of loss of AF. Both eyes were judged to be in the same group in 75% of patients. CONCLUSIONS: Areas of reduced AF are measurable, but are not equivalent to the area of dense Scotoma in 53% of patients. Measures of retinal sensitivity and Scotomas are necessary for defining retinal functional involvement in Stargardt disease.
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fixation patterns and reading rates in eyes with central Scotomas from advanced atrophic age related macular degeneration and stargardt disease
Ophthalmology, 1996Co-Authors: Janet S. Sunness, Carol A. Applegate, David Haselwood, Gary S RubinAbstract:Purpose: To study fixation patterns and reading rates in eyes with central Scotomas from geographic atrophy (GA) of age-related macular degeneration and to compare fixation patterns with those of patients with Stargardt disease. Methods: Scanning laser ophthalmoscope analysis of fixation patterns in eyes with 20/80 to 20/200 visual acuity. Included were 41 eyes of 35 patients with GA and 10 eyes of 5 patients with Stargardt disease. The patients with GA also were tested for maximum reading rate, and the size of the areas of atrophy were measured by fundus photograph analysis. Results: Sixty-three percent of GA eyes fixating outside the atrophy placed the Scotoma to the right of fixation in visual field space, 22% placed the Scotoma above fixation, and 15% placed it to the left, regardless of the laterality of the GA eye. Fixation was stable in subsequent years of testing for Scotoma placement to the right of or above fixation. All GA eyes fixated immediately adjacent to the atrophy. In contrast, seven of ten eyes with Stargardt disease fixated at a considerable distance from the Scotoma border, with the dense Scotoma far above the fixation site in visual field space. For the patients with GA, the maximum reading rate was highly correlated with size of the atrophic area, but not with age or visual acuity within the limited visual acuity range tested. There was a trend to more rapid reading with the Scotoma above fixation and slower reading with the Scotoma to the left. Conclusion: There is a preference for fixation with the Scotoma to the right in eyes with GA. Patients with Stargardt disease use different strategies for fixation, perhaps due to subdinical pathology adjacent to the atrophic regions. The size of the atrophic area in GA plays the predominant role in reading rate for eyes that have already lost foveal vision.
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landmark driven fundus perimetry using the scanning laser ophthalmoscope
Investigative Ophthalmology & Visual Science, 1995Co-Authors: Janet S. Sunness, Gary S Rubin, Ronald A. Schuchard, Naiming Shen, Gislin Dagnelie, David HaselwoodAbstract:Visual field measurement provides important information regarding the diagnosis, progression, and management of many ocular diseases. Most notably, visual fields are extremely important in glaucoma to diagnose and evaluate the progression of disease, in neuroophthalmologic disorders to aid in the determination of the site of involvement in the eye, optic nerve, or brain, and in some retinal diseases, such as retinitis pigmentosa, to assess the extent of involvement and visual disability. These evaluations are well served by our current methods of visual field determination, herein referred to as conventional visual field testing, which include Goldmann kinetic perimetry, Humphrey static perimetry, and similar techniques. However, conventional visual field determination is inadequate for the accurate evaluation of macular disorders or any retinal disorder in which foveal vision is compromised and the patient may have unstable fixation or extrafoveal fixation. Accuracy of the conventional visual field relies on the assumption that fixation is foveal and stable. If fixation is not foveal, the conventional visual field will still be mapped as though fixation is at the center (0°) of the field, so that all points tested will be shifted relative to their true retinal location. (A perimeter that uses the blind spot to test fixation may register fixation losses, but it is unable to correct for these.) If central fixation is unstable and there is significant eye movement during testing, Scotoma size will be incorrect. Often, eccentric fixation and unstable fixation coexist, and there is a combination of these errors in Scotoma location and size. In addition, there is often perceptual “filling in” of the area of the Scotoma so that even the Amsler grid, used as a screening test for changes in central vision, may not detect the presence of a Scotoma.1,2 Pericentral fixation lines to facilitate a patient’s centering on the fovea often still result in eccentric fixation. 3,4 Fundus perimeters are devices that provide for visualization of the fundus and the precise location of the stimulus on it. One can then see the exact test site on the retina and can correlate visual field defects to their true retinal positions.5 Several fundus perimeters have been designed and used in the past 30 years.6–14 The scanning laser ophthalmoscope (SLO) is the most recent and well-known fundus perimeter. It has allowed us to gain new information regarding the nature of visual loss in various macular diseases, including age-related macular degeneration and macular holes.1,6,7,15–25 However, because of difficulties in dealing with the additional data provided by SLO testing, methods of performing fundus perimetry have not used and have even ignored the advantage of viewing the fundus during testing. These difficulties include how to evaluate data correctly when the stimulus does not fall on the desired retinal location because of eye movement, how to ensure that the desired retinal areas are tested, and how to summarize the data. An additional problem is how to test for Scotomas that might not correspond to observable lesions rather than simply testing over or at borders of retinal lesions. A number of investigators have shown that in diabetes26–28 and other macular diseases,29 Scotomas may be present that do not correspond to observed retinal lesions; this is undoubtedly true in other retinal diseases, and these areas would be missed by testing only over observed retinal lesions. Finally, there must be a reliable method to test over the same retinal points when testing is repeated, even if fixation has shifted, to assess change over time.
David Haselwood - One of the best experts on this subject based on the ideXlab platform.
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fixation patterns and reading rates in eyes with central Scotomas from advanced atrophic age related macular degeneration and stargardt disease
Ophthalmology, 1996Co-Authors: Janet S. Sunness, Carol A. Applegate, David Haselwood, Gary S RubinAbstract:Purpose: To study fixation patterns and reading rates in eyes with central Scotomas from geographic atrophy (GA) of age-related macular degeneration and to compare fixation patterns with those of patients with Stargardt disease. Methods: Scanning laser ophthalmoscope analysis of fixation patterns in eyes with 20/80 to 20/200 visual acuity. Included were 41 eyes of 35 patients with GA and 10 eyes of 5 patients with Stargardt disease. The patients with GA also were tested for maximum reading rate, and the size of the areas of atrophy were measured by fundus photograph analysis. Results: Sixty-three percent of GA eyes fixating outside the atrophy placed the Scotoma to the right of fixation in visual field space, 22% placed the Scotoma above fixation, and 15% placed it to the left, regardless of the laterality of the GA eye. Fixation was stable in subsequent years of testing for Scotoma placement to the right of or above fixation. All GA eyes fixated immediately adjacent to the atrophy. In contrast, seven of ten eyes with Stargardt disease fixated at a considerable distance from the Scotoma border, with the dense Scotoma far above the fixation site in visual field space. For the patients with GA, the maximum reading rate was highly correlated with size of the atrophic area, but not with age or visual acuity within the limited visual acuity range tested. There was a trend to more rapid reading with the Scotoma above fixation and slower reading with the Scotoma to the left. Conclusion: There is a preference for fixation with the Scotoma to the right in eyes with GA. Patients with Stargardt disease use different strategies for fixation, perhaps due to subdinical pathology adjacent to the atrophic regions. The size of the atrophic area in GA plays the predominant role in reading rate for eyes that have already lost foveal vision.
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landmark driven fundus perimetry using the scanning laser ophthalmoscope
Investigative Ophthalmology & Visual Science, 1995Co-Authors: Janet S. Sunness, Gary S Rubin, Ronald A. Schuchard, Naiming Shen, Gislin Dagnelie, David HaselwoodAbstract:Visual field measurement provides important information regarding the diagnosis, progression, and management of many ocular diseases. Most notably, visual fields are extremely important in glaucoma to diagnose and evaluate the progression of disease, in neuroophthalmologic disorders to aid in the determination of the site of involvement in the eye, optic nerve, or brain, and in some retinal diseases, such as retinitis pigmentosa, to assess the extent of involvement and visual disability. These evaluations are well served by our current methods of visual field determination, herein referred to as conventional visual field testing, which include Goldmann kinetic perimetry, Humphrey static perimetry, and similar techniques. However, conventional visual field determination is inadequate for the accurate evaluation of macular disorders or any retinal disorder in which foveal vision is compromised and the patient may have unstable fixation or extrafoveal fixation. Accuracy of the conventional visual field relies on the assumption that fixation is foveal and stable. If fixation is not foveal, the conventional visual field will still be mapped as though fixation is at the center (0°) of the field, so that all points tested will be shifted relative to their true retinal location. (A perimeter that uses the blind spot to test fixation may register fixation losses, but it is unable to correct for these.) If central fixation is unstable and there is significant eye movement during testing, Scotoma size will be incorrect. Often, eccentric fixation and unstable fixation coexist, and there is a combination of these errors in Scotoma location and size. In addition, there is often perceptual “filling in” of the area of the Scotoma so that even the Amsler grid, used as a screening test for changes in central vision, may not detect the presence of a Scotoma.1,2 Pericentral fixation lines to facilitate a patient’s centering on the fovea often still result in eccentric fixation. 3,4 Fundus perimeters are devices that provide for visualization of the fundus and the precise location of the stimulus on it. One can then see the exact test site on the retina and can correlate visual field defects to their true retinal positions.5 Several fundus perimeters have been designed and used in the past 30 years.6–14 The scanning laser ophthalmoscope (SLO) is the most recent and well-known fundus perimeter. It has allowed us to gain new information regarding the nature of visual loss in various macular diseases, including age-related macular degeneration and macular holes.1,6,7,15–25 However, because of difficulties in dealing with the additional data provided by SLO testing, methods of performing fundus perimetry have not used and have even ignored the advantage of viewing the fundus during testing. These difficulties include how to evaluate data correctly when the stimulus does not fall on the desired retinal location because of eye movement, how to ensure that the desired retinal areas are tested, and how to summarize the data. An additional problem is how to test for Scotomas that might not correspond to observable lesions rather than simply testing over or at borders of retinal lesions. A number of investigators have shown that in diabetes26–28 and other macular diseases,29 Scotomas may be present that do not correspond to observed retinal lesions; this is undoubtedly true in other retinal diseases, and these areas would be missed by testing only over observed retinal lesions. Finally, there must be a reliable method to test over the same retinal points when testing is repeated, even if fixation has shifted, to assess change over time.
Ronald A. Schuchard - One of the best experts on this subject based on the ideXlab platform.
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Patient awareness of binocular central Scotoma in age-related macular degeneration.
Optometry and Vision Science, 2012Co-Authors: Donald C. Fletcher, Ronald A. Schuchard, Laura RenningerAbstract:PURPOSE: To assess whether age-related macular degeneration (AMD) patients are aware of binocular central visual field defects. METHODS: One hundred fifty-three consecutive AMD patients in their initial low-vision rehabilitation evaluation were immediately asked at the beginning of their visit (1) whether they were able to see any blind spots or defects in their field of vision and (2) whether they had any evidence or experiences that led them to believe that they had defects in their field of vision. They then had their vision assessed by binocular central visual field testing using the California Central Visual Field Test, binocular reading performance evaluated using the Smith-Kettlewell Reading Test (SK Read) and MN Read charts, and visual acuity measured using the ETDRS chart at 1 meter. Mean diameters of the Scotomas with borders near fixation were noted. RESULTS: Visual acuity median was 20/253 (range 20/40 to hand movements). Binocular Scotomas were present in 88% of patients (66% had dense Scotoma). Of patients with binocular Scotomas, 56% were totally unaware of their presence, even with dense Scotomas measuring up to 30° in diameter; 1.5% could fleetingly see a defect in their visual field on waking; and 44% related experiences of things "disappearing" on them. The median and range of Scotoma diameters for those unaware vs. those with some awareness of their Scotomas were comparable. There was no significant relationship of awareness of the Scotoma with age, acuity, Scotoma size, density, or duration of onset. Awareness of Scotoma was associated with fewer errors on the SK Read (p < 0.01). CONCLUSIONS: Low vision clinicians cannot depend on patients to report the presence of significant Scotomas; thus, appropriate testing must be performed. Presence of Scotomas decreased reading accuracy, but some awareness of the Scotomas had a tendency to improve accuracy. The value of rehabilitation programs aimed at increasing patient awareness of their Scotomas may be supported by this evidence.
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preferred retinal loci and macular Scotoma characteristics in patients with age related macular degeneration
Canadian Journal of Ophthalmology-journal Canadien D Ophtalmologie, 2005Co-Authors: Ronald A. SchuchardAbstract:Abstract Many patients with macular Scotomas due to age-related macular degeneration do not perceive black spots in the visual field where the Scotomas are located. Rather, they describe objects as “vanishing,” “jumping out of nowhere” or “having blurry parts,” or a combination of features. In addition, when the macular Scotoma affects the fovea, the visual system uses 1 or more preferred retinal loci (PRLs) as a “pseudofovea” to perform visual tasks. Visual function testing with the scanning laser ophthalmoscope has provided a wealth of information regarding how patients perceive the visual world and how the oculomotor system directs eye movements. This article describes 2 specific functions of the oculomotor system, fixation stability and refixation precision, with data collected from normally sighted people and patients with visual field loss. The implications of the characteristics of PRLs and macular Scotomas for clinical testing are discussed.
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Relative locations of macular Scotomas near the PRL: effect on low vision reading.
Journal of rehabilitation research and development, 1999Co-Authors: Donald C. Fletcher, Ronald A. Schuchard, G. WatsonAbstract:Patients referred for low vision rehabilitation had Minnesota Reading Acuity (MNRead), visual acuity (VA), and scanning laser ophthalmoscope (SLO) macular function testing performed in their initial evaluation to determine whether dense macular Scotomas near the preferred retinal locus (PRL) have a significant effect on the characteristics of reading based on rate. The 99 subjects had macular Scotoma characteristics relative to the fovea/PRL of: 22% only to the right; 15% only to the left; 26% both the right and left; 19% above or below; 17% had no dense Scotomas. Reading performance (maximum reading speed, critical print size, and reading acuity) was significantly different between the non-Scotoma group and all of the Scotoma groups. There was no statistically significant difference in the characteristics of reading based on rate between the four Scotoma groups: within each there was a wide variation in the characteristics of reading based on rate not fully explained by either VA or Scotoma location. The position of the Scotoma relative to the PRL was not a statistically significant factor in determining reading rate as found in studies on normally sighted people with artificial Scotomas. Other factors (e.g., maybe PRL ability in fixation and saccadic eye movements and/or cognitive ability) are significantly involved in determining reading rate characteristics in people with macular Scotomas.
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Preferred retinal loci relationship to macular Scotomas in a low-vision population.
Ophthalmology, 1997Co-Authors: Donald C. Fletcher, Ronald A. SchuchardAbstract:Purpose: The authors identified patterns in preferred retinal locus (PRL) ability and location relative to macular Scotomas in a low-vision patient population. Methods: Scanning laser ophthalmoscope macular perimetry and PRL testing were performed on 825 patients with low vision. The PRL location was determined, and a PRL scoring system was devised and used to measure the pursuit ability, fixation stability, and saccadic ability of the PRL. The characteristics of dense Scotomas within 2.5 degrees of the PRL were noted. Results: Eighty-four percent (1130 of 1339 eyes) of the eyes had an established PRL. Preferred retinal loci varied across the full range of ability scores and varied in size for fixation stability from 1.0° to 9.0° in diameter. There was a central dense Scotoma in 82.5% of the eyes, whereas 8.4% had a paracentral dense Scotoma. In 14.8% of the eyes, the PRL had no dense Scotomas on any of its borders; one, two, three, or four (a ring) borders had a dense Scotoma in 39.7%,19.0%, 9.0%, and 17.4% of eyes, respectively. When the PRL had only one Scotomatous border, the resulting field defect was located superior in 39.0%, right in 33.7%, left in 19.9%, and inferior in 7.5% of eyes. Conclusions: The majority of patients with low vision, as many as four of five patients, have dense Scotomas encumbering the PRL for visual tasks. Approximately one of six patients with low vision have the PRL completely surrounded by dense Scotomas. The visual system shows a strong tendency not to place a PRL anatomically above a Scotoma (field defect below fixation) and a weaker tendency not to place the PRL anatomically to the right of a Scotoma (field defect to the left of fixation). Macular perimetry and PRL evaluations can provide considerable information on the functional status of the macula, which may be useful to rehabilitation professionals.
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Adaptation to macular Scotomas in persons with low vision.
American Journal of Occupational Therapy, 1995Co-Authors: Ronald A. SchuchardAbstract:Persons with Scotomas in their central 20 degrees of vision often do not notice these blind spots within their visual field and have visual performance difficulties far exceeding what would be expected from standard vision tests. Before persons with macular Scotomas can be assisted to optimally use their remaining vision for a better quality of life, more must be known about how the visual system adapts to a macular Scotoma. Important issues include spatial and temporal characteristics of perceptual completion and metamorphopsia, development of preferred retinal loci for fixation and visual search, and dynamics of the preferred retinal locus development in terms of the changes in the eye movement system. With a full understanding of the visual system's adaptation to macular Scotomas, new low vision devices and training techniques can be proposed to promote independence in activities of daily living for the person with low vision.
Gary S Rubin - One of the best experts on this subject based on the ideXlab platform.
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The effects of simulated cataract on reading with normal vision and simulated central Scotoma.
Vision Research, 1999Co-Authors: Elisabeth M. Fine, Gary S RubinAbstract:Abstract Reading rates are slower for persons with low vision than for normally-sighted persons. This study investigated the change in reading performance and reading eye movements when we simulated the two most common causes of low vision — central field loss and cataract — and their combination (Scotoma+cataract). Three subjects read sentences with each of these simulated impairments at five different letter sizes. They required larger letters to read with the cataract or Scotoma than they did with normal vision, and larger still to read with Scotoma+cataract; the change in eye movements relative to normal vision was similar across conditions. When reading large letters (1.61°), the cataract had almost no effect, while the Scotoma and Scotoma+cataract reduced reading rate for two of the subjects. The cataract had a greater impact on performance relative to normal vision for these same two subjects, while for the third subject the cataract had a greater impact with the Scotoma in place. Cataract extraction tends to be postponed in patients with central field loss because it is not perceived to be beneficial. The findings from this study, as well as others, suggest that patients with central field loss would benefit from cataract extraction.
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Effects of cataract and Scotoma on visual acuity: a simulation study.
Optometry and Vision Science, 1999Co-Authors: Elisabeth M. Fine, Gary S RubinAbstract:Central field loss (CFL) and cataract both decrease visual acuity. For patients with CFL, visual acuity is further reduced when the acuity target is more visually complex. We tested visual acuity for targets of varying complexity (letters alone, letters flanked by one or two x's on each side, and words) in subjects with normal vision and in the presence of a simulated cataract, simulated Scotoma, and their combination (Scotoma + cataract). Visual acuity was best with normal vision and worst with Scotoma + cataract for all of the acuity targets. There was little difference in visual acuity between the letters alone and flanked letters, and visual acuity was best for words under all vision conditions. The cataract had a greater impact on visual acuity when the subject's central visual field was clear (normal vision) than when it was occluded by the simulated Scotoma.
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fixation patterns and reading rates in eyes with central Scotomas from advanced atrophic age related macular degeneration and stargardt disease
Ophthalmology, 1996Co-Authors: Janet S. Sunness, Carol A. Applegate, David Haselwood, Gary S RubinAbstract:Purpose: To study fixation patterns and reading rates in eyes with central Scotomas from geographic atrophy (GA) of age-related macular degeneration and to compare fixation patterns with those of patients with Stargardt disease. Methods: Scanning laser ophthalmoscope analysis of fixation patterns in eyes with 20/80 to 20/200 visual acuity. Included were 41 eyes of 35 patients with GA and 10 eyes of 5 patients with Stargardt disease. The patients with GA also were tested for maximum reading rate, and the size of the areas of atrophy were measured by fundus photograph analysis. Results: Sixty-three percent of GA eyes fixating outside the atrophy placed the Scotoma to the right of fixation in visual field space, 22% placed the Scotoma above fixation, and 15% placed it to the left, regardless of the laterality of the GA eye. Fixation was stable in subsequent years of testing for Scotoma placement to the right of or above fixation. All GA eyes fixated immediately adjacent to the atrophy. In contrast, seven of ten eyes with Stargardt disease fixated at a considerable distance from the Scotoma border, with the dense Scotoma far above the fixation site in visual field space. For the patients with GA, the maximum reading rate was highly correlated with size of the atrophic area, but not with age or visual acuity within the limited visual acuity range tested. There was a trend to more rapid reading with the Scotoma above fixation and slower reading with the Scotoma to the left. Conclusion: There is a preference for fixation with the Scotoma to the right in eyes with GA. Patients with Stargardt disease use different strategies for fixation, perhaps due to subdinical pathology adjacent to the atrophic regions. The size of the atrophic area in GA plays the predominant role in reading rate for eyes that have already lost foveal vision.
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landmark driven fundus perimetry using the scanning laser ophthalmoscope
Investigative Ophthalmology & Visual Science, 1995Co-Authors: Janet S. Sunness, Gary S Rubin, Ronald A. Schuchard, Naiming Shen, Gislin Dagnelie, David HaselwoodAbstract:Visual field measurement provides important information regarding the diagnosis, progression, and management of many ocular diseases. Most notably, visual fields are extremely important in glaucoma to diagnose and evaluate the progression of disease, in neuroophthalmologic disorders to aid in the determination of the site of involvement in the eye, optic nerve, or brain, and in some retinal diseases, such as retinitis pigmentosa, to assess the extent of involvement and visual disability. These evaluations are well served by our current methods of visual field determination, herein referred to as conventional visual field testing, which include Goldmann kinetic perimetry, Humphrey static perimetry, and similar techniques. However, conventional visual field determination is inadequate for the accurate evaluation of macular disorders or any retinal disorder in which foveal vision is compromised and the patient may have unstable fixation or extrafoveal fixation. Accuracy of the conventional visual field relies on the assumption that fixation is foveal and stable. If fixation is not foveal, the conventional visual field will still be mapped as though fixation is at the center (0°) of the field, so that all points tested will be shifted relative to their true retinal location. (A perimeter that uses the blind spot to test fixation may register fixation losses, but it is unable to correct for these.) If central fixation is unstable and there is significant eye movement during testing, Scotoma size will be incorrect. Often, eccentric fixation and unstable fixation coexist, and there is a combination of these errors in Scotoma location and size. In addition, there is often perceptual “filling in” of the area of the Scotoma so that even the Amsler grid, used as a screening test for changes in central vision, may not detect the presence of a Scotoma.1,2 Pericentral fixation lines to facilitate a patient’s centering on the fovea often still result in eccentric fixation. 3,4 Fundus perimeters are devices that provide for visualization of the fundus and the precise location of the stimulus on it. One can then see the exact test site on the retina and can correlate visual field defects to their true retinal positions.5 Several fundus perimeters have been designed and used in the past 30 years.6–14 The scanning laser ophthalmoscope (SLO) is the most recent and well-known fundus perimeter. It has allowed us to gain new information regarding the nature of visual loss in various macular diseases, including age-related macular degeneration and macular holes.1,6,7,15–25 However, because of difficulties in dealing with the additional data provided by SLO testing, methods of performing fundus perimetry have not used and have even ignored the advantage of viewing the fundus during testing. These difficulties include how to evaluate data correctly when the stimulus does not fall on the desired retinal location because of eye movement, how to ensure that the desired retinal areas are tested, and how to summarize the data. An additional problem is how to test for Scotomas that might not correspond to observable lesions rather than simply testing over or at borders of retinal lesions. A number of investigators have shown that in diabetes26–28 and other macular diseases,29 Scotomas may be present that do not correspond to observed retinal lesions; this is undoubtedly true in other retinal diseases, and these areas would be missed by testing only over observed retinal lesions. Finally, there must be a reliable method to test over the same retinal points when testing is repeated, even if fixation has shifted, to assess change over time.
Eric Castet - One of the best experts on this subject based on the ideXlab platform.
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Gaze-contingent simulation of retinopathy: Some potential pitfalls and remedies
Vision Research, 2011Co-Authors: Carlos Aguilar, Eric CastetAbstract:Many important results in visual neuroscience rely on the use of gaze-contingent retinal stabilization techniques. Our work focuses on the important fraction of these studies that is concerned with the retinal stabilization of visual filters that degrade some specific portions of the visual field. For instance, macular Scotomas, often induced by age related macular degeneration, can be simulated by continuously displaying a gaze-contingent mask in the center of the visual field. The gaze-contingent rules used in most of these studies imply only a very minimal processing of ocular data. By analyzing the relationship between gaze and Scotoma locations for different oculo-motor patterns, we show that such a minimal processing might have adverse perceptual and oculomotor consequences due mainly to two potential problems: (a) a transient blink-induced motion of the Scotoma while gaze is static, and (b) the intrusion of post-saccadic slow eye movements. We have developed new gaze-contingent rules to solve these two problems. We have also suggested simple ways of tackling two unrecognized problems that are a potential source of mismatch between gaze and Scotoma locations. Overall, the present work should help design, describe and test the paradigms used to simulate retinopathy with gaze-contingent displays. (C) 2011 Elsevier Ltd. All rights reserved.
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small effect of interline spacing on maximal reading speed in low vision patients with central field loss irrespective of Scotoma size
Investigative Ophthalmology & Visual Science, 2010Co-Authors: Aurelie Calabrese, Jeanbaptiste Bernard, Louis Hoffart, Geraldine Faure, Fatiha Barouch, John Conrath, Eric CastetAbstract:PURPOSE. It has been suggested that crowding, the adverse low-level effect due to the proximity of adjacent stimuli, explains slow reading in low-vision patients with absolute macular Scotomas. According to this hypothesis, crowding in the vertical dimension should be released by increasing the vertical spacing between lines of text. However, studies with different experimental paradigms and only a few observers have given discrepant results on this question. The purpose of this study was to investigate this issue with a large number of patients whose macular function was carefully assessed. METHODS. MP1 microperimetry examination was performed for each low-vision patient. Only eyes with an absolute macular Scotoma and no foveal sparing (61 patients with AMD, 90 eyes; four patients with Stargardt disease, eight eyes) were included. Maximal reading speed was assessed for each eye with French sentences designed on the MNREAD test principles. RESULTS. The effect of interline spacing on maximal reading speed (MRS) was significant although small; average MRS increased by 7.1 words/min from standard to double interline spacing. The effect was weak irrespective of PRL distance from the fovea and Scotoma area and regardless of whether an eccentric island of functional vision was present within the Scotoma. CONCLUSIONS. Increasing interline spacing is advisable only for very slow readers (<20 words/min) who want to read a few words (spot reading). Vertical crowding does not seem to be a major determinant of maximal reading speed for patients with central Scotomas. (Invest Ophthalmol Vis Sci. 2010; 51: 1247-1254) DOI: 10.1167/iovs.09-3682
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Small Effect of Interline Spacing on Maximal Reading Speed in Low-Vision Patients with Central Field Loss Irrespective of Scotoma Size
Investigative Ophthalmology & Visual Science, 2010Co-Authors: Aurelie Calabrese, Jeanbaptiste Bernard, Louis Hoffart, Geraldine Faure, Fatiha Barouch, John Conrath, Eric CastetAbstract:PURPOSE. It has been suggested that crowding, the adverse low-level effect due to the proximity of adjacent stimuli, explains slow reading in low-vision patients with absolute macular Scotomas. According to this hypothesis, crowding in the vertical dimension should be released by increasing the vertical spacing between lines of text. However, studies with different experimental paradigms and only a few observers have given discrepant results on this question. The purpose of this study was to investigate this issue with a large number of patients whose macular function was carefully assessed. METHODS. MP1 microperimetry examination was performed for each low-vision patient. Only eyes with an absolute macular Scotoma and no foveal sparing (61 patients with AMD, 90 eyes; four patients with Stargardt disease, eight eyes) were included. Maximal reading speed was assessed for each eye with French sentences designed on the MNREAD test principles. RESULTS. The effect of interline spacing on maximal reading speed (MRS) was significant although small; average MRS increased by 7.1 words/min from standard to double interline spacing. The effect was weak irrespective of PRL distance from the fovea and Scotoma area and regardless of whether an eccentric island of functional vision was present within the Scotoma. CONCLUSIONS. Increasing interline spacing is advisable only for very slow readers (
