Disease relevance of Photophobia

• Total colourblindness (OMIM 216900), also referred to as rod monochromacy (RM) or complete achromatopsia, is a rare, autosomal recessive inherited and congenital disorder characterized by photophobia, reduced visual acuity, nystagmus and the complete inability to discriminate between colours [1].
• Deletion of psb29 in Synechocystis 6803 results in slower growth rates under high light intensities, increased light sensitivity, and lower PSII efficiency, without affecting the PSII core electron transfer activities [2].
• At 2 hours, other migraine headache characteristics, such as functional disability (P =.002), photophobia (P =.02), and phonophobia (P =.08), were significantly improved after treatment with acetaminophen vs placebo [3].
• Other toxicities included nausea, vomiting, diarrhea, conjunctivitis, photophobia, cytosine arabinoside fever, skin rashes, and hepatic dysfunction [4].
• Also, zolmitriptan effectively relieved migraine-associated symptoms such as nausea, photophobia and phonophobia, and reduced activity impairment [5].

Psychiatry related information on Photophobia

• The cry(b) mutation reduces the light sensitivity of the fly's clock, yet locomotor activity rhythms in constant darkness or light-dark cycles are relatively normal, because the rhodopsins compensate for the lack of cryptochrome function [6].

High impact information on Photophobia

• Restoration of light sensitivity to the bleached opsin requires chemical regeneration of 11-cis-retinaldehyde through an enzymatic pathway called the visual cycle [7].
• This change stabilizes the light-labile PHYA protein in light and causes a 100-fold shift in the threshold for far-red light sensitivity [8].
• Cyclic GMP increases photocurrent and light sensitivity of retinal cones [9].
• Sumatriptan also reduced nausea and photophobia significantly better than placebo [10].
• Suppression of melatonin secretion under the two light intensities was measured and the difference between their effects was taken as a measure of light sensitivity [11].

Chemical compound and disease context of Photophobia

• Light sensitivity of the opsin pigment is restored through a multistep pathway called the visual cycle, which effects all-trans to 11-cis re-isomerization of the retinoid chromophore [12].
• The increased light sensitivity of the transformants appears to result from a limitation in photochemical energy utilization and/or dissipation which correlates with a greatly diminished photosynthetic response to exogenous (CO2 + HCO3-), especially under conditions where the chloroplast inorganic carbon transport system is not induced [13].
• Mutant seeds had more rapid germination, reduced requirement for light, and decreased far-red light sensitivity, unraveling cytokinin functions in seed germination control [14].
• Subsequent inactivation of apcE by an erythromycin resistance marker led to reduction of the phycobilin-to-chlorophyll ratio and to a further decrease in light sensitivity [15].
• Photoreception in Neurospora crassa: correlation of reduced light sensitivity with flavin deficiency [16].

Biological context of Photophobia

• Our results indicate that XPD overexpression in SK-MG-4 cells leads to cisplatin resistance without affecting the nucleotide excision repair activity or UV light sensitivity of the cell [17].
• This loss in light sensitivity reveals that post-translational farnesylation is a critical step for the formation of membrane-associated Galphabetagamma required for transmitting light activation from rhodopsin to phospholipase Cbeta [18].
• In oxygenated glucose-bicarbonate Ringer's medium with added Percoll, they display normal dark currents, light sensitivity, and photocurrent kinetics for several hours [19].
• This study was undertaken to observe the effect on the differential light sensitivity in glaucoma suspects produced by a long-term reduction in intraocular pressure (IOP) with timolol maleate [20].
• It appears that GABA participates in the modulation of light sensitivity during light- and dark-adaptation processes and that this action is mediated by GABAA receptors [21].

Anatomical context of Photophobia

• While considerable attention has been paid to the role of melanopsin in the generation of intrinsic light sensitivity in the retinal ganglion cells of mammals, nothing is known about the photoreceptive capacity of the horizontal cells of the fish retina in which both VA opsin and melanopsin are expressed [22].
• Restoration of light sensitivity requires chemical re-isomerization of retinaldehyde by an enzymatic pathway called the visual cycle in the retinal pigment epithelium [23].
• Bovine recoverin regulates rhodopsin phosphorylation and controls photoreceptor light sensitivity in a Ca(2+)-dependent manner [24].
• Keratosis follicularis spinulosa decalvans is a rare, X-linked genodermatosis characterized by follicular hyperkeratosis, scarring alopecia of the scalp, eyebrows and eyelashes, corneal dystrophy and photophobia [25].
• Further, concanavalin A binding of protoplasts resulted in a loss in NADH oxidase activity and its blue light sensitivity suggesting apoplastic location and glycoprotein nature of the blue light sensitive NADH oxidase system in Cuscuta [26].

Gene context of Photophobia

• New pleiotropic mutants were isolated that express either the phoA, psiE or psiO promoter constitutively and simultaneously alter bacterial alkaline phosphatase regulation, carbon utilization or ultraviolet light sensitivity [27].
• The SRS2 mutations also efficiently suppress the ultraviolet light sensitivity of the parent strains [28].
• Electroretinogram recordings revealed a significant loss of light sensitivity in eyes of transgenic flies that express mutated Ggammae [18].
• Light sensitivity and adaptation, general characteristics of rod photoreceptor cell vision, allow rods to modulate their response depending on the lighting environment to which they are exposed [29].
• The mutation in atrC caused extreme UV light sensitivity and proved to occur within the polA (DNA polymerase I) locus [30].

Analytical, diagnostic and therapeutic context of Photophobia

• Static perimetry with an SLO is a useful technique for the assessment of localized light sensitivity and fixation stability in patients with macular disease [31].
• CONCLUSIONS: Photophobia and corneal infiltration, although generally severe after 15 years of age, could be treated with topical cysteamine and corneal transplantation [32].
• The reduction in symptom severity was significantly greater in the levocabastine group than in the control group for photophobia (p < 0.003) after 1 week, and for photophobia (p < 0.008), irritation (p = 0.05) and itchy eyes (p = 0.05) at the end of the trial [33].
• For the assessment of localized light sensitivity and stability of fixation, patients with CSR were evaluated by fundus perimetry with a scanning laser ophthalmoscope (SLO 101, Rodenstock Instruments) [31].

References