PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Cone dystrophy”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed2006

Retinoids restore normal cyclic nucleotide sensitivity of mutant ion channels associated with cone dystrophy.

PURPOSE: To determine whether inhibition of cyclic nucleotide-gated (CNG) ion channels by retinoids might be useful in treating degenerative retinal diseases in which either the CNG channels are hypersensitive to 3',5'-cyclic guanosine monophosphate (cGMP) or the photoreceptor cGMP concentration is elevated. METHODS: Patch clamp (electrophysiological) methods were used to measure activation by cGMP of wild-type human cone (hCNGA3), mutant cone (hCNGA3-N471S), and wild-type bovine rod (bCNGA1) CNG channels heterologously expressed in Xenopus oocytes. Cyclic GMP-activated currents were measured in excised, inside-out membrane patches before and after treatment with either all-trans retinal (ATR) or all-trans C22 aldehyde, which is too long to fit into the chromophore binding pocket of opsin and therefore cannot activate the visual transduction cascade. RESULTS: At physiological cGMP concentrations, 150 nM ATR reduced the open probability of the mutant cone CNG channel by reducing its apparent cGMP affinity to that of the normal cone channel. Furthermore, all-trans C22 aldehyde similarly inhibited the mutant cone channel as well as normal rod and cone CNG channels. CONCLUSIONS: Our results raise the possibility that retinoids, such as all-trans C22 aldehyde, that inhibit CNG channels without affecting the transduction cascade, may be useful in treating degenerative retinal diseases in which either the cGMP concentration is elevated or the CNG channels are hypersensitive to cGMP.

Animals↗
PubMed1989

Rod-cone dystrophy associated with a rod system electroretinogram obtained under photopic conditions.

A 14-year-old girl with a history of night blindness and poor visual acuity was examined. Cystic-appearing lesions were apparent in the fovea, and pigmentary changes were observed in the midperipheral retina. Electroretinograms (ERGs) recorded from the dark- and light-adapted eye were similar in waveform, implicit time, and approximate amplitude. Results of examination of the spectral characteristics of the light-adapted ERG demonstrated that the recordings represented activity of the rod system, despite the presence of a background field, which eliminates the response of the rod system in normal subjects.

Adaptation, Ocular↗
PubMed2001

Clinical and oculographic response to Dexedrine in a patient with rod-cone dystrophy, exotropia, and congenital aperiodic alternating nystagmus.

PURPOSE: We report a child with retinal dystrophy and congenital (a)periodic alternating nystagmus (APAN) who responded immediately with improved visual function and electrooculographic parameters after taking the psychopharmacologic stimulant Dexedrine Spansule (Glaxo-Smith Kline, NC, USA) as part of treatment for his Attention Deficit Disorder. DESIGN: Interventional case report. METHODS: General ophthalmic, ocular motor and sensorimotor examinations and ocular motility recordings were performed before and after administration of the drug Dexedrine Spansule. RESULTS: The patient's binocular visual acuity improved only at 1.5 after medicine hours from 20/63 to 20/50, his exotropic deviation decreased from 25 to 10 prism diopters, his stereopsis increased from none to 800 sec/arc and ocular motility recordings showed increased foveation periods and more and lengthened APAN transition/null zones. CONCLUSION: For unexplained reasons the stimulant Dexedrine "paradoxically" improved the nystagmus, binocular function and visual acuity in this patient with retinal dystrophy and congenital nystagmus. This observation may be the basis for investigation of a new pharmacological treatment approach to patients with congenital nystagmus or strabismus.

Attention Deficit Disorder with Hyperactivity↗
PubMed1987

Neuro-ophthalmic presentation of cone dysfunction syndromes in the adult.

Cone dysfunction syndromes are probably part of the spectrum of cone-rod degenerations and can present with widely varying clinical pictures. Thus, although the age of onset is usually before the third decade, patients can present at any age, and, although family history is usually positive, in typical cases it may be quite negative. Patients can have initially very subtle, bizarre, or poorly described visual complaints so that numerous examiners may label them "functional" or "malingering." They can present with the classic symptoms of hemeralopia, poor acuity, and reduced color vision, but these complaints may be absent. Visual acuity and color vision can be normal or severely reduced and the fundi may show classic changes such as bulls-eye maculopathy, macular choroidal atrophy, pigment clumping in the maculae, mild peripheral pigmentary changes, or a fundus flavimaculata-like change. The patients here reported were considered as having normal fundi by several competent ophthalmologists as a rule, however. Visual fields can vary from normal to ring scotomas, central scotomas, and other interesting types of defects, even simulating a hemianopia. Although involvement is usually symmetrical between the two eyes, this is not always the case, and one of our patients had a strictly uniocular cone dystrophy. Cone dysfunction can be considered in a patient of any age even with normal acuity, good color vision, and a normal ophthalmoscopic examination. A high index of suspicion should prompt specific questioning about hemeralopia, or reduced visual function in brightly illuminated situations, and better vision in twilight or under dim illumination. Patients may falsely describe hemeralopia as "glare" or "photophobia." Careful testing of color vision, a meticulous tangent screen examination, and specifically looking for diffuse narrowing of retinal arterioles in a patient with an otherwise normal fundus appearance will usually suffice to prompt the clinician to order electroretinography, which is the definitive diagnostic criterion for the cone dystrophies. It is important to consider this diagnosis before embarking on an otherwise fruitless and expensive neuroimaging investigation.

Adult↗
PubMed1996

Molecular genetics of central retinal dystrophies.

A range of chorioretinal dystrophies that principally affect the central retina have recently been associated with either specific genetic mutations or mapped to refined genomic loci. Mutations of two genes, peripherin/RDS (chromosome 6p) and TIMP3 (chromosome 22q) have been shown to be of particular importance to this group of disorders. Other conditions such as Stargardt's disease, Best's disease, pattern dystrophy, cone dystrophy and cone-rod dystrophy have been mapped to different regions of the genome, however the underlying genetic mutations await identification. Molecular genetic diagnostic techniques are now available for a number of central choroidoretinal dystrophies allowing for earlier, accurate diagnosis and laying the groundwork for future studies of potential therapeutic protocols.

Eye Proteins↗
PubMed1990

Idiopathic photoreceptor dysfunction causes unexplained visual acuity loss in later adulthood.

Progressive visual loss, caused by initially unrecognized retinal photoreceptor dysfunction predominantly affecting cones, developed in six patients in late adulthood. Because of minimal ophthalmoscopic retinal abnormalities, the patients initially had been suspected of having optic neuropathy or psychogenic visual loss. The correct diagnosis was ultimately established by finding electroretinographic abnormalities and color discrimination losses out of proportion to visual acuity loss. In no case was a causative agent or a family history of photoreceptor disease identified. In many other respects, however, features of the patients' illness resemble those described previously under the headings of cone dysfunction syndrome, cone dystrophy, cone degeneration, and cone-rod dystrophy.

Aged↗
PubMed2005

Functional consequences of progressive cone dystrophy-associated mutations in the human cone photoreceptor cyclic nucleotide-gated channel CNGA3 subunit.

Progressive cone dystrophies are a genetically heterogeneous group of disorders characterized by early deterioration of visual acuity and color vision, together with psychophysical and electrophysiological evidence of abnormal cone function and cone degeneration. Recently, three mutations in the gene encoding the CNGA3 subunit of cone photoreceptor cyclic nucleotide-gated (CNG) channels have been linked to progressive cone dystrophy in humans. To investigate the functional consequences of these mutations, we expressed mutant human CNGA3 subunits in Xenopus oocytes, alone or together with human CNGB3, and studied these channels using patch-clamp recording. Compared with wild-type channels, homomeric and heteromeric channels containing CNGA3-N471S or CNGA3-R563H subunits exhibited an increase in apparent affinity for cGMP and an increase in the relative agonist efficacy of cAMP compared with cGMP. In contrast, R277C subunits did not form functional homomeric or heteromeric channels. Cell surface expression levels, determined using confocal microscopy of green fluorescent protein-tagged subunits and patch-clamp recording, were significantly reduced for both R563H and R277C but unchanged for N471S. Overall, these results suggest that the plasma membrane localization and gating properties of cone CNG channels are altered by progressive cone dystrophy-associated mutations, providing evidence that supports the pathogenicity of these mutations.

Animals↗