Objective To observe the effect of visible light on apoptosis of cultured human retinal pigment epithelium (RPE) cells. Methods Being the light source,500lx,(2 000±500)lx and (3 400±200)lx cold white light were used. The duration of exposure was 0,6,12 and 24 hours respectively. Apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labelling, Annexin V-flunorescein isothiocyanate/Propidium iodium labelling and flow cytometry. Results Apoptosis and necrosis were found in cultured human RPE cells which were exposed to visible light.(1)A significant increase in apoptotic and necrotic percentages was consistent with a higher light intensity.(2)Apoptosis was the main response to shorter (6 h and 12 h) exposure duration,while necrosis was more pronounced correlated to the prolongation of post-exposure culture (P＜0.05),and the longer the post-exposure period was, the more apoptotic necrosis were seen.Thirty-six hours after exposure the necrotic percentages were more pronounced (P＜0.01). Conclusions Visible light (＞500 lx) increases the proportion of apoptosis and necrosis of human RPE cells in vitro.The extent is related to exposure intensity and duration. It demonstrates that the lower intensity and the shorter duration of exposure to light are, the more pronounced apoptotic percentages are observed,otherwise necrosis. (Chin J Ocul Fundus Dis, 2002, 18: 227-230)
Objective To investigate the relationship between exposure intensity and illumination time of blue light and replicative senescence of rat retinal pigment epithelial （RPE） cells.Methods Thirtysix 12-14 weeks Wistar rats were kept in the cage with a bluelight bulb ［(450plusmn;10) nm］, and were randomly divided into four groups (no light，nature light，500 lx light and 1000 lx light illumination), each has nine rats. The rats in each group were further divided into three subgroups according to illumination time (one month，two months or three months). Eyeballs were collected after intraperitoneal injection of 10% chloral hydrate. The right eye of each rat was embedded in paraffin and sectioned for hematoxylineosin (HE) staining, while frozen sections of the left eye were stained for the senescence-associated beta;-galactosidase (SA-beta;-Gal). The data were analyzed by SPSS11.5 statistical software.Results The amounts of SA-beta;-Gal positive RPE cells were significantly different between all groups under the same illumination time 17 (P＝0.000）, and between all subgroups of different illumination time with same exposure intensity （P＜0.01）except for the control group (no light). Conclusion Bluelight can induce replicative senescence in rat RPE cells in an intensity and timedependent manner.
Purpose To evaluate the prostag landins(PG) levels and to identify the effect of dexamethasone(DXM) on PG in response to photochemical insult in rat retina. Methods The experiments were performed on 36 SD rats which were separated into two groups,control and treated groups,and the latter received daily intraperitoneal injections of DXM (1 mg/kg) for 5 consecutive days,starting 3 days before light exposure.The animals were continually exposed to green fluorescent light(510-560 nm)with an illuminance level of (1900plusmn;106.9)lx for 24 hrs.The retinal concentration of PGE 2 and 6-keto-PGF1alpha; were tested at 6hrs,1,3,7 and 14 days after light exposure. Results The PGE2 and 6-keto-PGF1alpha; levels of the control groups (37.50plusmn;2.75,48.06plusmn;4.0 4,81.90plusmn;4.89) pg/mg and (4.68plusmn;0.69,7.50plusmn;0.57,10.40plusmn;0.71) pg/mg had significantly higher values than those of the treated rats(20.60plusmn;4.28,37.36plusmn; 3.34,54.85plusmn;4.57) pg/mg and (2.50plusmn;0.59,4．68plusmn;0.81,6.87plusmn;1.10)pg/mg (Plt;0.01) after 6 hrs,1 and 3 days light exposure respectively. Conclusion By inhibition of PG synthesis,the DXM may play an ameliorative effect on retinal photochemical injury of rats. (Chin J Ocul Fundus Dis,1999,15:94-96)
Objective To investigate the degenerative changes in the inner rat retina after photic injury.Methods After 24 hour-dark adaptation, sixty Lewis rats were exposed in a ventilated green plexiglass chamber that transmitted continuous green light between 480-520 nm with an intensity of 900～1 000 lx. After 24 hour exposure, the rats stayed in darkness and were sacrificed after 1 day, 3,7 or 14 days. The neurons in the inner retina were marked by immunohisto chemical technique and observed by light and electronic microscope.Results The apoptotic photoreceptor cells were noted after photic injury. The degeneration and decreasing number of rod bipolar cells were found after 3 days; the edema of horizontal cells occurred after 1 day but ameliorated gradually; decreasing number of amacrine cells was found after 1 day; sustained edema of ganglion cells and prolifeeration of the Müller cells were found after photic injury. Pyknotic and edematous neruronal degenerations of inner retina were found in ultrastructural study.Conclusion The neurons in the inner retina as well as Müller cells are involved in the degeneration after photic injury. Different neurons manifest different patterns of degeneration.(Chin J Ocul Fundus Dis，2003，19：201-268)
Objective To assess the effects of 670nm LED (lightemitting diode) to protect the photoreceptor from the lightinduced damage in a rat model. Methods 32 SD rats were randomly assigned to one of eight groups: untreated control group, the LEDtreated control group, three groups of lightinduced damage，and three groups of lightinduced damage treated with LED. Lightinduced damage result from exposing to constant light for 3 hours of different illuminations of 900，1800 and 2700 lx, respectively. The LED treatment (50 mW) was delivered for 30 minutes at 3 hours before the light damage and 0，24 and 48 hours after the light damage. Retinal function and morphology were measured by electroretinogram (ERG) and histopathology assay. Results The illumination of 900 lx for 3 hours did not damage the rat retina. The illumination of 1800 lx for 3 hours resulted in thinner ONL and no OS and IS. The ratio of damaged area/total retinal area was 048plusmn;012， the damaged thickness of ONL/normal ONL (L5 ) was 039plusmn;007，and the amplitude of ERG b wave was (431plusmn;120) mu;V. With the LED treatment the ratio of damaged area decreased (M6=017plusmn;0.12, P5/6=0.002), and the ratio of the damaged thickness of ONL also decreased (L6=0.22plusmn;0.09, P5/6lt;0.01), and the amplitude of ERG b wave increased to (1011plusmn;83) mu;V（P5/6lt;0.001）. The illumination of 2700 lx for 3 hours caused severed damage to the rat retina and the LED could not protect them significantly. Conclusions 670 nm LED treatment has an evident protective effect on retinal cells against light-induced damage, which may be a simple and effective therapy to prevent or to delay agerelated macular degeneration.
Objective To observe the effect of blue light on apoptosis of cultured human retinal pigment epithelial (RPE) cells in vitro. Methods Human RPE cells were exposed to blue light, and the cells were divided into 3 groups: group A, with various intensity of illumination; group B: with same intensity but different time of illumination; group C: with same intensity and time of illumination but different finish time of the culture. The apoptosis of RPE cells was observed by TdT-dUTP terminal nick-end labeling (TUNEL) and annexin V-fluoresein isothiocyanate (FITC)/propidium iodide (PI) flow cytometry, and transmission electron microscopy. Results The positive cells stained by TUNEL shrinked and turned round, whose nuclei concentrated and congregated like the crescent or hat. Cracked nuclei and membrane bleb were found. Swollen mitochondrial, disappeared inner limiting membrane of mitochondria, and dilation of the rough endoplasmic reticulum with metabolite were observed by transmission electronmicroscopy. In group A, mild damage of RPE cells was found when the threshold value of the intensity of illumination was less than（500±100）lx, and the apoptosis and necrosis of RPE cells aggravated as the intensity of illumination increased; in group B, as the time of illumination extended, the number of apoptotic RPE cells didn′t increase while the necrosis increased; in group C, 6 and 12 hours after illumination, apoptosis of cells was the main injury, while apoptosis with necrosis was found and necrotic cells increased as the time of illumination was prolonged. Conclusions Illumination with blue light may cause damages of human RPE cells in vitro, with the modalities of apoptosis, apoptotic necrosis and necrosis. The extent of injury is dependent on intensity and duration of the illumination. (Chin J Ocul Fundus Dis, 2005, 21: 384-387)
Objective To observe the expression of alpha;A-and alpha;B-in retina after blue-light exposure.Methods Forty female Wistar rats were divided randomly into 4 groups:control group,and blue-light exposure for 6,12,and 24 hours groups, with 10 rats in each group. The rats in the control group were not intervened.The other three groups of rats were exposed to blue fluorescent lights for 6,12,and 24 hours respcetively. Then the rats were kept in darkness for 12 hours. The globes were enucleated after anaesthesia.The immunohistochemistry and Western blot were performed to detect the expression of alpha;A and alpha;B-crystallin in retina.Results The absorbance value (A value) of retina alpha;A-crystallin was 1.40573plusmn;0.70748 in the control group, and were 4.317 51plusmn;0.412 97, 7.397 08plusmn;1.947 90, 9.634 32plusmn;2.377 61, respectively in the other 3 groups; the difference among the groups was significant (F=24.569，P＜0.001). The A value of retina alpha;B-crystallin is 0.129 36plusmn;0.033 93 in the control group, and were 0.507 17plusmn;0.117 55, 7.345 43plusmn;2.292 97, 4.042 26plusmn;3.890 23, respectively in the other 3 groups; the difference among the groups was significant（F=40.102，P＜0.001）. The results of Western blot showed that the expression of alpha;A and alpha;B crystallin in groups with bluelight exposure was obviously higher than that in the control group.Conclusions Blue light may up-regulate the expression of alpha;A-and alpha;B-crystallin in ratsprime; retina.
Photosensitive occipital lobe epilepsy (POLE) is a rare idiopathic reflex focal epilepsy that can occur in all age groups. It is characterized by occipital lobe seizures induced by flashing stimuli (flashing sunlight, video games, TV commercials and programs, etc.). Photoparoxysmal response on EEG is induced by intermittent photic stimulation; Ictal EEG shows rapid spike rhythms are originated from the occipital region. There are no obvious abnormalities in brain image. POLE responds well to anti-seizure medications and has a good prognosis. This article reviews the research progress on POLE in order to improve the clinician’s understanding and reduce the rates of missed diagnosis and misdiagnosis.
Objective To observe the pathological and functional changes of retinal photochemical damages exposed to green flurescent light. Methods The Sprague Dawley rats were continually exposed to green fluorescent light with an illuminancem level of (1 900plusmn;106.9) Lx for 24 hours.The changes of retinal morphology and morphometrics and flash electroretinogram were studied before light exposure and at the 6th hour,6th day and 14th day after light exposure. Results At the 6th hours after light exposure,the outer nuclear layer(ONL)of retina becoma thinner compared with that bfore light exposure.The thickness of ONL decreased by 23.91% and the inner and outer segments appeared disorderly arranged.At the 6th day after light exposure the thickness of ONL is thinner than that at the6th hour,i.e.decreased by 46.6%. At the 14th day after light exposure the thickness of ONL decreased by 42.40%.Flash electroretinogram showed that the amplitudes of a and b wave decreased continuously at the 6th hour and 6th day and unrecovered at the 14th day after light exposure. Conclusion This model might be an ideal one for research on retinal photochemical damage. (Chin J Ocul Fundus Dis,1998,14:101-103)