Objective To explore the possible mechanism of Yiqi Mingmu Pills（ 益气明目丸） in treatment of retinitis pigmentosa（ RP）. Methods A total of 24 RCS rats were randomly divided into blank group

model group and Yiqi Mingmu Pills group

with 8 rats in each group. The blank group RCS rats（ rdy +/+

p +/+）

and the model group RCS rats（ rdy-/

p-/-） were given 12 ml/（ kg·d） of normal saline by gavage. The Yiqi Mingmu Pills group RCS rats（ rdy-/

p-/-） were given 7. 8 g/（ kg ·d） of suspension turbid solution of Yiqi Mingmu Pills. After intragastric administration for 30 days

the structure of retina layers was observed by HE staining. Expressions of Fas and FasL in retinal tissues of each group were detected by immunohistochemistry and Western Blot method. Results HE staining showed that the retina thickness of rats in Yiqi Mingmu Pills group was significantly thicker than that of the model group. The retinal pigment epithelial band was partially visible

and part of the outer nuclear layer photoreceptor sensory ciliary layer was visible. The number of photoreceptor cell nuclei was higher than that of the model group. The outer layer

outer core layer

and the visual cone layer were clearer and thicker than the model group. The results of immunohistochemistry showed that the expression of Fas and FasL protein in the model group was significantly higher than that in the blank group（ P < 0. 01）. Compared with the model group

the expression of Fas and FasL protein in Yiqi Mingmu Pill group decreased significantly（ P < 0. 05 or P < 0. 01）

and there was no significant difference with the blank group（ P > 0. 05）. Western blot analysis showed that the expression of Fas and FasL protein in the model group was significantly higher than that in the blank group（ P < 0. 01）. Compared with the model group

the expression of Fas protein in Yiqi Mingmu Pill group was not statistically significant（ P > 0. 05）

and the expression of FasL protein was significantly lower

but was still higher than that of the blank group（ P < 0. 01）.Conclusion Yiqi Mingmu Pills has protective effects on the ultrastructure of RP retina. Yiqi Mingmu Pills can reduce the apoptosis of retinal photoreceptor cells and protect the visual cells by inhibiting the expression of Fas and Fas L on the retina.