Photoaversion in retinitis pigmentosa.

Gawande, Atul; Donovan, William J.; Ginsburg, Arthur P.; Marmor, Michael F.

doi:10.1136/bjo.73.2.115

Cited by 22 publications

(12 citation statements)

References 5 publications

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“…The rod system under normal conditions exhibits larger amplitudes in comparison with the cone system. A common finding in patients with retinal degeneration is photophobia or photoaversion [37]. This pathologically increased light sensitivity, which is frequently one of the first symptoms of retinal degenerations, renders ERG procedures with brighter stimuli highly uncomfortable, leading to blinking and The rod system has a critical fusion frequency of approximately 28 Hz [38].…”

Section: The 9 Hz Flicker Protocolmentioning

confidence: 99%

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Assessment of “non-recordable” electroretinograms by 9 Hz flicker stimulation under scotopic conditions

et al. 2011

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To refine methods of electroretinographical (ERG) recording for the analysis of low retinal potentials under scotopic conditions in advanced retinal degenerative diseases. Standard Ganzfeld ERG equipment (Diagnosys LLC, Cambridge, UK) was used in 27 healthy volunteers (mean age 28 ± SD 8.5 years) to define the stimulation protocol. The protocol was then applied in clinical routine and 992 recordings were obtained from patients (mean age 40.6 ± 18.3 years) over a period of 5 years. A blue stimulus with a flicker frequency of 9 Hz was specified under scotopic conditions to preferentially record rod-driven responses. A range of stimulus strengths (0.0000012-6.32 scot. cd s/m² and 6-14 ms flash duration) was tested for maximal amplitudes and interference between rods and cones. Analysis of results was done by standard Fourier Transformation and assessment of signal-to-noise ratio. Optimized stimulus parameters were found to be a time-integrated luminance of 0.012 scot. cd s/m² using a blue (470 nm) flash of 10 ms duration at a repetition frequency of 9 Hz. Characteristic stimulus strength versus amplitude curves and tests with stimuli of red or green wavelength suggest a predominant rod-system response. The 9 Hz response was found statistically distinguishable from noise in 38% of patients with otherwise non-recordable rod responses according to International Society for Clinical Electrophysiology of Vision standards. Thus, we believe this protocol can be used to record ERG potentials in patients with advanced retinal diseases and in the evaluation of potential treatments for these patients. The ease of implementation in clinical routine and of statistical evaluation providing an observer-independent evaluation may further facilitate its employment.

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Section: The 9 Hz Flicker Protocolmentioning

confidence: 99%

“…For technical assistance with measurements of Doc Ophthalmol (2012) 124: [27][28][29][30][31][32][33][34][35][36][37][38][39] …”

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confidence: 99%

Assessment of “non-recordable” electroretinograms by 9 Hz flicker stimulation under scotopic conditions

et al. 2011

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“…A variety of alterations in the VCS spatial-frequency profile have been observed in ocular diseases such as glaucoma, which manifests a low spatial-frequency deficit (70)(71)(72), macular disease (73,74), retinitis pigmentosa (75)(76)(77)(78), type 1 diabetes before observable retinopathy (79)(80)(81), and other distal visual conditions (82,83). With damage more proximal to the visual cortex, VCS deficits have been observed in cases of optic nerve neuropathy (84), optic nerve compression (85), and cerebral lesions (86).…”

Section: Discussionmentioning

confidence: 99%

Apartment residents' and day care workers' exposures to tetrachloroethylene and deficits in visual contrast sensitivity.

Schreiber¹,

Hudnell²,

Geller³

et al. 2002

Environ Health Perspect

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Tetrachloroethylene (also called perchloroethylene, or perc), a volatile organic compound, has been the predominant solvent used by the dry-cleaning industry for many years. The U.S. Environmental Protection Agency (EPA) classified perc as a hazardous air pollutant because of its potential adverse impact on human health. Several occupational studies have indicated that chronic, airborne perc exposure adversely affects neurobehavioral functions in workers, particularly visual color discrimination and tasks dependent on rapid visual-information processing. A 1995 study by Altmann and colleagues extended these findings, indicating that environmental perc exposure at a mean level of 4,980 microg/m(3) (median=1,360 microg/m(3)) alters neurobehavioral functions in residents living near dry-cleaning facilities. Although the U.S. EPA has not yet set a reference concentration guideline level for environmental exposure to airborne perc, the New York State Department of Health set an air quality guideline of 100 microg/m(3). In the current residential study, we investigated the potential for perc exposure and neurologic effects, using a battery of visual-system function tests, among healthy members of six families living in two apartment buildings in New York City that contained dry-cleaning facilities on the ground floors. In addition, a day care investigation assessed the potential for perc exposure and effects among workers at a day care center located in the same one-story building as a dry-cleaning facility. Results from the residential study showed a mean exposure level of 778 microg/m(3) perc in indoor air for a mean of 5.8 years, and that perc levels in breath, blood, and urine were 1-2 orders of magnitude in excess of background values. Group-mean visual contrast sensitivity (VCS), a measure of the ability to detect visual patterns, was significantly reduced in the 17 exposed study participants relative to unexposed matched-control participants. The groups did not differ in visual acuity, suggesting that the VCS deficit was of neurologic origin. Healthy workers in the day care investigation were chronically exposed to airborne perc at a mean of 2,150 microg/m(3) for a mean of 4.0 years. Again, group-mean VCS, measured 6 weeks after exposure cessation, was significantly reduced in the nine exposed workers relative to matched controls, and the groups did not differ significantly in visual acuity. These results suggested that chronic, environmental exposure to airborne perc adversely affects neurobehavioral function in healthy individuals. Further research is needed to assess the susceptibility of the young and elderly to perc-induced effects, to determine whether persistent solvent-induced VCS deficits are a risk factor for the development of neurologic disease, and to identify the no observable adverse effect level for chronic, environmental, perc exposure in humans.

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“…A potentially quantifiable parameter that may decrease with treatment is light aversion (e.g., Gawande et al, 1989), and this may provide not only an outcome measure but also a practical benefit to these patients, who otherwise show varying degrees of disability under ambient lights.…”

Section: Considerations For Future Clinical Trials In Bcmmentioning

confidence: 99%

Human Cone Visual Pigment Deletions Spare Sufficient Photoreceptors to Warrant Gene Therapy

et al. 2013

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Human X-linked blue-cone monochromacy (BCM), a disabling congenital visual disorder of cone photoreceptors, is a candidate disease for gene augmentation therapy. BCM is caused by either mutations in the red (OPN1LW) and green (OPN1MW) cone photoreceptor opsin gene array or large deletions encompassing portions of the gene array and upstream regulatory sequences that would predict a lack of red or green opsin expression. The fate of opsin-deficient cone cells is unknown. We know that rod opsin null mutant mice show rapid postnatal death of rod photoreceptors. Using in vivo histology with high-resolution retinal imaging, we studied a cohort of 20 BCM patients (age range 5-58) with large deletions in the red/green opsin gene array. Already in the first years of life, retinal structure was not normal: there was partial loss of photoreceptors across the central retina. Remaining cone cells had detectable outer segments that were abnormally shortened. Adaptive optics imaging confirmed the existence of inner segments at a spatial density greater than that expected for the residual blue cones. The evidence indicates that human cones in patients with deletions in the red/green opsin gene array can survive in reduced numbers with limited outer segment material, suggesting potential value of gene therapy for BCM.

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Photoaversion in retinitis pigmentosa.

Cited by 22 publications

References 5 publications

Assessment of “non-recordable” electroretinograms by 9 Hz flicker stimulation under scotopic conditions

Assessment of “non-recordable” electroretinograms by 9 Hz flicker stimulation under scotopic conditions

Apartment residents' and day care workers' exposures to tetrachloroethylene and deficits in visual contrast sensitivity.

Human Cone Visual Pigment Deletions Spare Sufficient Photoreceptors to Warrant Gene Therapy

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