[The study of laser-induced choroidal neovascularization in rhesus monkeys]

To investigate the morphological and functional changes of the laser-induced choroidal neovascularization (CNV) in rhesus monkeys.

Experimental study. Eight adult rhesus monkeys weighted 4 to 7 kg were used in this study. CNVs were induced with small high-energy laser spots at short pulse duration by an argon green laser. Eyes were monitored weekly by color fundus photography, fluorescence fundus angiography (FFA) , and optical coherence tomography (OCT) . Fluorescein leaking intensities of grade 4 CNV lesions were analyzed by the method of ANOVA for repeated measures. Electroretinogram (ERG) was performed before laser photocoagulation and 56 days after laser photocoagulation and the data were analyzed with paired t-test.

(1) FFA revealed that the mean intensities of grade 4 CNV lesions were 89.44 ± 26.28, 97.56 ± 26.47, 110.22 ± 29.76, 100.26 ± 29.24, 91.77 ± 28.11, 77.76 ± 24.85 and 63.23 ± 22.34 on day 14, day 21, day 28, day 35, day 42, day 49, and day 56 respectively and the differences were statistically significant (F = 39.715, P < 0.01) . The differences between any time-point and its previous time-point were also statistically significant (t14-21 = 4.824, P < 0.01; t21-28 = 5.225, P < 0.01; t28-35 = 7.378, P < 0.01;t35-42 = 2.954, P < 0.05; t42-49 = 5.386, P < 0.01; t49-56 = 6.138, P < 0.01). (2) OCT images showed retinal edema, subretinal fluid and hyper-reflective lesions of CNVs in the laser sites and histopathology showed that fibrovascular tissues together with proliferating retinal pigment epithelium cells were seen in the laser sites. (3) ERG data revealed that implicit time of dark-adapted b wave (t = 4.23, P < 0.01) increased while the amplitudes of dark-adapted a wave (t = 6.35, P < 0.01) , dark-adapted b wave (t = 3.12, P < 0.01) and light-adapted b wave (t = 3.93, P < 0.01) decreased 56 days after laser photocoagulation compared with those before laser photocoagulation.

The laser-induced CNV in non-human primate model shows continuous leakage on FFA examination and reduced amplitudes as well as increased implicit time on ERG examination, suggesting that laser-induced CNV primate model not only could be used to study the pathogenesis of CNV formation but also could be used for screening of drug effectiveness.