Investigative ophthalmology & visual science
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Invest. Ophthalmol. Vis. Sci. · Aug 2014
Observational StudyHigh-resolution imaging of photoreceptors in macular microholes.
To assess photoreceptor structure in macular microholes by using adaptive optics scanning laser ophthalmoscopy (AO-SLO) and spectral-domain optical coherence tomography (SD-OCT) and compare with visual acuity. ⋯ Cone disruption occurs in eyes with macular microholes and a larger cone disruption area translates into a poorer visual acuity. Macular microholes, which are commonly observed as foveal cone inner and outer segment disruptions, may occur in eyes with or without vitreofoveal traction.
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Invest. Ophthalmol. Vis. Sci. · Aug 2014
Hyperosmolar tears enhance cooling sensitivity of the corneal nerves in rats: possible neural basis for cold-induced dry eye pain.
Tear hyperosmolarity is a ubiquitous feature of dry-eye disease. Although dry-eye patients' sensitivity to cooling is well known, the effects of tear hyperosmolarity on a small amount of cooling in the corneal nerves have not been quantitatively examined. Recently reported corneal afferents, high-threshold cold sensitive plus dry-sensitive (HT-CS + DS) neurons, in rats is normally excited by strong (>4°C) cooling of the cornea, which, when applied to healthy humans, evokes the sensation of discomfort. However, corneal cooling measured between blinks does not exceed 2°C normally. Thus, we sought to determine if these nociceptors could be sensitized by hyperosmolar tears such that they are now activated by small cooling of the ocular surface. ⋯ These results demonstrate that after exposure to hyperosmolar tears, these nociceptive corneal neurons now begin to respond to the slight cooling normally encountered between blinks, enabling the painful information to be carried to the brain, which could explain the cooling-evoked discomfort in dry eye patients.
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Invest. Ophthalmol. Vis. Sci. · Aug 2014
Pseudomonas aeruginosa infectious keratitis in a high oxygen transmissible rigid contact lens rabbit model.
To establish a rabbit model of infectious Pseudomonas aeruginosa keratitis using ultrahigh oxygen transmissible rigid lenses and characterize the frequency and severity of infection when compared to a non-oxygen transmissible lens material. ⋯ These data indicate that in the absence of adequate tear clearance, the presence of P. aeruginosa trapped under the lens overrides the protective effects of oxygen on surface epithelial cells. These findings also suggest that alternative pathophysiological mechanisms exist whereby changes under the lens in the absence of frank hypoxic damage result in P. aeruginosa infection in the otherwise healthy corneal epithelium.
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Invest. Ophthalmol. Vis. Sci. · Aug 2014
Mitochondrial haplogroups are associated with severity of diabetic retinopathy.
To determine if specific mitochondrial haplogroups associate with nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). ⋯ In this study, DR patients from mitochondrial haplogroup H were more likely to have PDR, while DR patients from haplogroup Uk were less likely to have PDR. The association was independent of the major clinical variables affecting PDR. The mitochondrial haplogroups were as strong a risk factor for PDR as were elevated HgbA1c levels.
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Invest. Ophthalmol. Vis. Sci. · Aug 2014
Retinal ischemia/reperfusion injury is mediated by Toll-like receptor 4 activation of NLRP3 inflammasomes.
Retinal ischemia/reperfusion (IR) is common in eye disorders. Pattern-recognition receptors (PRRs) are reported to initiate sterile inflammatory response. The role of PRRs in retinal IR injury is currently unknown. Thus, we investigated the expression and function of membrane and cytoplasmic PRRs during retinal IR. ⋯ These findings suggest that TLR4-signaling activation, triggered by damage-associated molecular patterns, regulates the activation of the NLRP3 inflammasomes and is responsible for the function of the retina in retinal IR injury.