LMX2582: SPI interface

Tool/software:

Hi,

We are using LMX2582 for clk generation and it's output is connected to LMX1214 clock buffer. Both IC's SPI interfaces are interfaced to FPGA (2.5V bank).

Do we need any optocouplers (similar to HCPL063L) in the SPI path to FPGA?

Are there any use cases why optocouplers are required on digital interface signals of PLL/clock buffer?

Thanks