Background : To study the formation and distribution of perifoveal cysts in an idiopathic macular hole and their correlation with retinal blood flow. Method: There were 16 patients in the small hole group, and 23 patients in the large hole group. In the preoperative procedure, we measured the number, the total area and the average size of the cysts in the inner nuclear layer, outer plexiform and Henle fiber layer complex around the hole; and the vascular density of the retinal capillary plexuses of all cases. Postoperatively, we measured the retinal capillary plexuses vascular density in 17 eyes. Results: The number and the total area of the cysts in the inner nuclear layer of the large hole group were greater than those of the small hole group (t=-2.882, P =0.007, t= -3.412 P =0.002). And we came to the same conclusion in the outer plexiform and Henle fiber layer complex (t=-3.935 P =0.000, t=-4.335 P =0.000). The average cystic area of the inner nuclear layer and outer plexiform and Henle fiber layer complex had no significant difference between the two groups (t=0.178 P =0.860, t=-1.767 P =0.085). There was a significant correlation among the idiopathic macular hole diameter, the number and the total area of cysts in the outer plexiform and Henle fiber layer complex, the vascular density of the retinal superficial capillary plexuses and deep capillary plexuses; the respective coefficients were -0.725, -0.474, -0.314, -0.768, and +0.624. Conclusions: 1. The diameter of the idiopathic macular hole was related to the formation of cysts around the hole. 2. Multiple mechanisms are involved in the interaction between the cystic space around the idiopathic macular hole and the retinal capillary plexuses.