Objective To investigate the effect of micropulse di ode laser treatment on the retina in Brown-Norway rats (BN Rats). Methods 130 eyes of BN rats received irradiance of different powers of micr opulse diode laser with 810nm wavelength through a contact lens. Fundus color photography and fundus fluorescein angiography (FFA) were performed on day 1, 3, 7, 14 and 28 days after treatment. Animals were sacrificed on 1, 3, 7, 14 and 28 days separately for historical study. The expression of heat shock protein-70 (HSP-70) in the retina was observed with immunohistochemistry. Cell apoptosis of retina tissue was examined by TdT mediated dUTP nick end labeling (TUNEL). Results (1) No change was found in no visible reaction laser spots by light microscope. High duty cycles with threshold and suprathreshold en ergies can produce severe damage even to the inner nuclear layer. (2) HSP-70 ex pression was markedly increased in the inner nuclear layer at 1d after micropulse diode laser. This increase in HSP-70 expression peaked at day 3 whereafter a decline near to normal at 2 weeks was detected. (3) Apoptosis was detected mainl y in retinal pigment epithelium, outer nuclear layer, inner nuclear layer and ev en choroid by TUNEL after micropulse diode laser treatment. The TUNEL-positive cells increased with the laser power. Maximum TUNEL-positive cells could be seen at day 3 after treatment. Conclusions The retinal injury has positive relationship with laser energy. The thermal damage is confined to the RPE and spare the neurosensory retina when using threshold power (50mW) with 50% duty-cycle and supra-threshold power with high duty-cycle (100mW，5%～15%). The hyper expression of HSP-70 and apoptosis mechanism may play an important role in the tissue repair process. (Chin J Ocul Fundus Dis,2008,24:122-126)
ObjectiveTo observe the changes of macular choroidal thickness before and after laser treatment for diabetic retinopathy patients. Methods For patients with diabetes by fundus fluorescein angiography (FFA) examination, diagnosed as severe non-proliferative and proliferative diabetic retinopathy and in accordance with the laser photocoagulation treatment indications of 23 patients (45 eyes) included in the study. There were 10 cases of male, 13 cases of female; the average age was (55.48±5.43) years old. All patients underwent macular grid laser photocoagulation and pan-retinal photocoagulation. The macular choroidal thickness before and after laser treatment was measured by enhanced depth imaging technique of optical coherence tomography during follow-up at 1, 2, 3 weeks and one month at specific sites of choroidal. The specific sites included subfoveal choroidal thickness (SFCT), from the foveal 1mm, 3mm, 6mm distance of nasal choroidal thickness (NCT) and temporal choroidal thickness (TCT). ResultsOne week after the treatment, SFCT, NCT1 mm, NCT3 mm, TCT1 mm, TCT3 mm, TCT6 mm were obviously thickening(t=4.728, 4.422, 3.759, 3.743, 5.713, 2.502; P < 0.05). Two weeks after the treatment the SFCT, NCT1 mm, NCT3 mm, TCT1 mm, TCT3 mm were decreased gradually(t=3.189, 2.122, 2.742, 2.196, 2.076; P < 0.05).The choroidal thickness returned to pretreatment level from 2 weeks to 4 weeks after treatment, the NCT6 mm had no obvious change in the whole treatment period(P > 0.05). ConclusionThe choroidal thickness was significantly thicker after laser photocoagulation treatment within 1 week, with the time prolonging the choroidal thickness gradually decreases.
Objective To observe the effect of panretinal photocoagulation (PRP) on the expression of cyclooxygenase-2 (COX-2), vascular endothelial cell growth factor (VEGF) in epiretinal membrane of proliferative diabetic retinopathy (PDR). Methods Atotal of 35 patients (35 eyes) with PDR and underwent plana vitrectomy were enrolled in this study. The patients were divided into non-PRP group (19 patients, 19 eyes) and PRP group (16 patients, 16 eyes) depends on if they had received PRP before surgery. The epiretinal membranes stripped during operation were collected for pathological examination. The histopathological features was observed by haematoxylin and eosin stain. The expression of CD34, COX-2 and VEGF, and microvessel density (MVD) were measured by immunohistochemistry method. Results Many new dispersed capillary blood vessels were found in the thick epiretinal membranes of non-PRP group, while scattered small blood vessels were found in the relatively thin epiretinal membranes of PRP group. MVD value was (7.42±1.39) in the non-PRP group and (4.56±1.22) in the PRP group, which was lower than the non-PRP group (t=6.41, P<0.01). The expression of CD34, COX-2 and VEGF in the tissues of epiretinal membrane in PRP group were obviously lower than the non-PRP group (t=6.147, 5.944, 7.445; P<0.01). Conclusion PRP can effectively inhibit the expression of COX-2 and VEGF in epiretinal membrane of PRP patients.
Objective To observe visual field outcome and refractive status of patients with retinopathy of prematurity (ROP) treated by laser photocoagulation. Method The data of 39 ROP patients (73 eyes) who received laser photocoagulation were retrospectively analyzed and compared with 13 normal control subjects (25 eyes) whose age and sex were matched with ROP group. There were 24 males (45 eyes) and 15 females (28 eyes) in ROP group, with an average age of (7.0±1.28) years. The first laser treatment was carried out at postnatal age (PA) of (38.74±3.82) weeks, the birth weight (BW) of (1402.33±369.61) g and the number of laser burns was (517.86±277.40). The control group included 7 females (13 eyes) and 6 males (12 eyes), with an average age of (7.17±0.96) years. The age (t=0.691) and gender (χ2=1.425) were comparable between the two groups (P=0.491, 0.233). The data of patients and controls were retrospectively analyzed including best corrected visual acuity, refractive examination, automated perimetry test. The differences of the mean deviation (MD) of visual field and the spherical equivalent (SE) between these two groups were comparatively observed. ROP patients were divided into no VF loss group (MD≤2 dB) and VF loss group (MD＞2 dB), mild VF loss group (MD≤6 dB) and moderate VF loss group (MD＞6 dB) according to the results of automated perimetry test, the differences of gestational age (GA), PA, BW, number of laser burns and SE between these groups were comparatively observed. Results The MD in ROP group and control group were 4.87±5.12 dB and 1.27±3.34 dB, respectively; the difference between the two groups was statistically significant (t=–4.01,P＜0.001). The subgroup analysis showed that BW, number of laser burns, and SE were significantly different between no VF loss group and VF loss group (t=2.074, –1.996, –2.162;P=0.042, 0.026, 0.034); while the GA was not significantly different between these two groups (t=1.973,P=0.052). The difference of PA was not statistical significant different between mild VF loss group and moderate VF loss group (t=2.03,P=0.051) and SE was significantly different between the above two groups (t=3.283,P=0.002). For refractive outcomes, the BW and ROP stage correlated with SE significantly (r=–0.304, –0.387;P=0.015, 0.002). The mean BCVA in ROP group was 0.84±0.23, and 59 eyes (91.2%) with BCVA better than 0.5. Conclusion Laser treatment for ROP tends to have less effect on long term refractive status and VF loss, with good visual outcome.