Equal spaced Photoshop concentric circles / rings feature does not exist but you can create the design via the filter menu and gallery and halftone found in the sketch section
Fill the document with white via the edit menu and then set the foreground color to black and background to white or inverted (set them as required but for op art designs, black and white is always perfect). Go to the filter gallery and select the halftone and set the type to be circle and set contrast to the max and set size to required value and this can be anything. Generate the artwork, these can be added to the background or a new layer. You can also quickly add a bit of a blur via the blur menu and Gaussian blur or motion or box etc
The design does not have to be applied over the entire image, you can create a selection and the halftone effect is applied to that region only
You can use the selections in combo with a layer and then create multiple layers with your designs. It should be noted that the layer cannot be empty as the effect will not work so fill it with white beforehand or another color. As layers can be warped, distorted and have effects added to them as well. And that design can be duplicated over and over to fill the artwork
You can also re-color the concentric rings / circles by using adjustment layers such as hue / saturation as well as photo filter etc
You can apply all kinds of effects to the designs. Either use the design on the background or a layer. If on a layer, goto the layer menu and smart objects and convert to a smart filter and then use oil paint or glass filter etc as a smart filter. You can also go to the edit menu and transform and use warp etc to distort the design in countless ways