ABSTRACT
The aim of this study was to compare the relative therapeutic efficacies of three different light sources for treating winter depression. A balanced incomplete block crossover design was employed, whereby all patients (n = 18) were randomly assigned to two out of the three treatment conditions: white, red and blue light. The degree of depression was assessed by the 21-item Hamilton Depression Rating Scale. The data suggest that at a photon density of 2.3 X 10(15) photons/s/cm2, white light has greater therapeutic benefit than red or blue light. It is clear that a larger sample population should be tested to confirm this result. This preliminary finding indicates that light sources currently in use for phototherapy could not be improved by narrowing the wavelengths provided and shifting them towards either end of the visible spectrum.
Subject(s)
Bipolar Disorder/therapy , Depressive Disorder/therapy , Phototherapy/methods , Seasons , Adult , Bipolar Disorder/psychology , Depressive Disorder/psychology , Female , Humans , Male , Phototherapy/instrumentation , Psychiatric Status Rating ScalesABSTRACT
The effect of repeated exposures to low-intensity, near-ultraviolet (UV) radiation on the retinas of phakic, aphakic, and pseudophakic monkey eyes was studied. Ten eyes (4 aphakic eyes, 3 pseudophakic eyes, and 3 normal phakic eyes) of five rhesus monkeys were used. The near-UV radiation was generated by a high-pressure mercury vapor lamp with a total radiance of 14.43 mW/cm2/sr. Exposure regimens were 5 minutes a day for 10 days, 15 minutes a day for 5 days, or 60 minutes a day for 5 days. The retinas of aphakic and pseudophakic eyes were exposed to a daily dose of more than 0.97 J/cm2, or a total dose of more than 4.9 J/cm2 in 5 days at a retinal irradiance of more than 1.0 mW/cm2. Three of four aphakic eyes and one of three pseudophakic eyes showed clinical and pathologic retinal lesions after radiation. None of the three phakic eyes was damaged. The retinal lesions showed mild opalescent thickening ophthalmoscopically and retinal pigment epithelial staining by fluorescein angiography. Histopathologically, the retinal pigment epithelium was the site of primary injury by near-UV radiation.
Subject(s)
Aphakia/complications , Cataract Extraction , Lenses, Intraocular , Radiation Injuries, Experimental/etiology , Retina/radiation effects , Ultraviolet Rays/adverse effects , Animals , Dose-Response Relationship, Radiation , Fluorescein Angiography , Fundus Oculi , Macaca mulatta , Pigment Epithelium of Eye/radiation effects , Pigment Epithelium of Eye/ultrastructure , Radiation Injuries, Experimental/pathology , Retina/ultrastructureABSTRACT
Several clinical observations suggest the necessity of protective measures to prevent eye damage from solar ultraviolet radiation. Recommendations for protection are given.
Subject(s)
Radiation Injuries , Sunlight/adverse effects , Ultraviolet Rays/adverse effects , Vision Disorders/etiology , Dose-Response Relationship, Radiation , Eyeglasses , Humans , Photochemistry , Retinal Diseases/etiology , Risk Factors , Time Factors , Vision Disorders/prevention & controlABSTRACT
Adult rhesus and pigtail monkeys were exposed to a uniform field of light from daylight fluorescent lamps to determine the initial site and characteristics of structural retinal damage induced by continuous exposure and the threshold intensity required to produce the effects. Electron microscopic examination revealed that the initial site of damage is the photoreceptor outer segments. Damage remained restricted to the outer segments at intensities as high as 24,700 lux and with 12 hr exposure periods repeated for up to 4 days. Rods were swollen at the distal tip and showed disc membrane separation. Come outer segments were affected at the proximal end with vesiculation and membrane rearrangement. The threshold intensity for morphological changes to comes in the macula for a single 12 hr exposure was between 195 and 361 mu W/cm2 at the retina (400 to 700 mm; uncorrected for ocular transmittance), whereas the threshold for changes in rods was higher, at between 361 and 615 mu W/cm2. These levels correspond to between 5900 and 10,800 lux (550 to 1000 ft-cd) for comes and 10,800 to 19,400 lux (1000 to 1800 ft-cd) for rods of monkeys with fully dilated pupils. The paramacular areas of the retina were less sensitive to damage than macular areas of the same animal. No paramacular changes were observed in animals exposed to 10,800 lux or less. The patched (control) eyes of each monkey remained structurally normal in both the macula and paramacula at all exposure levels. These results demonstrate the sensitivity of the adult primate retina to damage by relatively moderate levels of light.
