Dark adapted vision

Jackson, GR, Owsley, C, and McGwin, G, 1999. Aging and dark adaptation. Vision Res 39, 3975-3982. 

Fulton AB, Rushton WA. The human rod ERG correlation with psychophysical responses in light and dark adaptation. Vision Res 1978 18(7) 793-800. 

Another aspect of visual function that requires further study in children in relation to lead exposure is light and dark adaptation. Several animal studies suggest that rods (which mediate scotopic, dark-adapted vision) are more susceptible than cones (which mediate photopic, light-adapted vision) to lead... 

Lamb, TD and Pugh, EN, 2004. Dark adaptation and the retinoid cycle of vision. Prog Retin Eye Res 23, 307-380. 

Ophthalmic - Transient stinging and burning tearing ciliary spasm conjunctival vascular congestion temporal, peri-, or supra-orbital headache superficial keratitis-induced myopia blurred vision poor dark adaptation reduced visual acuity in poor illumination in older individuals and in individuals with lens opacity. 

In adults maintained on vitamin A-deficient diets for a period of months, there are a number of early signs, apparent before the impairment of dark adaptation impairment of the senses of taste, smell, and balance and distortion of color vision, with impaired sensitivity to green light. With the exception of the effects on color vision, these can all be attributed to dedifferentiation of ciliated epithelia (Sauberlich et al., 1974 Hodges et al., 1978). 

Of interest is that decreased color vision and decreased dark adaptation are also certain OADRs, whereas corneal ulceration, diplopia, eyelid edema, and intracranial hypertension are also associated but considered possible OADRs. 

Retinal pigmentary changes, visual field defects, color vision loss Retinal pigmentary changes, disturbances of dark adaptation, color vision loss, visual field defects Impairment of dark adaptation, visual field defects, vascular attenuation Color vision disturbances, entoptic phenomena Color vision disturbances... 

The peripheral lesions can occm with or without simultaneous macular involvement (Figure 35-10). Other changes include attenuated retinal vessels, optic atrophy, peripheral visual field loss, abnormal color vision, and a subnormal electroretinogram (ERG). The feet that the dark-adaptation threshold is normal, or omy minimally abnormal, further differentiates this condition flom retinitis pigmentosa. 

Thioridazine can cause significant retinal toxicity, leading to reduced visual acuity, changes in color vision, and disturbances of dark adaptation.These symptoms typically occur 30 to 90 days after initiation of treatment. The fundus often appears normal during the early stages of symptoms, but within several weeks or months a pigmentary... 

The precise mechanism whereby digoxin produces a toxic effect may involve inhibition of Na K -activated adenosine triphosphatase, an enzyme that plays a vital role in maintaining normal cone receptor function.This would explain the drug-induced interference with both dark adaptation and color vision. 

Central vision may recover VFs may recover over months or remain permanent. CV and dark adaptation changes are usually permanent. 

Certain abnormal meibomian gland secretion/gland atrophy, increased tear film osmolarity, decreased tolerance to CL, ocular discomfort, blepharoconjunctivitis, keratitis, corneal opacities, decreased vision, photophobia decreased dark adaptation, myopia intracranial hypertension (IH). 

In one prospective study in 17 patients with hemoljdic anemia (aged 5-25 years) lens opacities were found in 41%, changes in the retinal pigment epithelium in 35%, tortuosity of retinal vessels in 24%, dilatation and sheathing of retinal vessels in 18%, defects in color vision in 29%, and abnormal dark adaptation in 18% (56). In many other studies much lower frequencies were found. Perhaps retinal injury is related to the depletion of metals such as zinc, copper, and/or iron (57). On the other hand, ocular and auditory disturbances are not infrequent in patients with thalassemia, iron storage diseases (58,59), or uremia (45), and may be coincidental in patients receiving deferoxamine (60). 

Impaired night vision and dark adaptation (SEDA-10, 25) 3... 

The retina has been considered" " to be a doubic-.sense organ in which the rods arc concerned with colorless vision at low light intensities and the cones are concerned with color vision at high light inicn.silics. A dark-adapted, excised retina is rose red when it is exposed to light. it.s color... 

Humans deficient in vitamin A lose their ability for dark adaptation. Rod vision is affected more than cone vision. Upon depletion of retinol from liver and blood, the concentrations of retinol and rhodopsin in the retina fall. Unless the deficiency is overcome, opsin, lacking the stabilizing effect of retinal, decays and anatomical deterioration of the rods outer segments occurs. In rats maintained on a vitamin A-deficient Set, irreversible ultrastructural changes leading to blindness then supervene, a process that takes -10 months. Following short-term deprivation of vitamin A, dark adaptation can be restored to normal by the addition of retinol to the Set, but this restoration takes several weeks. The reason for this delay is unknown. 

Retinal photocoagulation is the current standard for the treatment of diabetic retinopathy. The treatment destroys the diseased retina in the extrafoveal areas with the purpose of preventing the disease from reaching the visual axis and reduce central vision. However, the destruction of the retina in extrafoveal areas imposes adverse effects such as blurring of vision, constriction of the visual field, and impaired dark adaptation. Consequently, during the past years, considerable efforts have been invested in developing treatment modalities with less or no adverse effects based on pharmacological intervention. 

Twilight vision n. Rod vision by the dark-adapted eye in dim light. 

---