This is a review article from two units in the UK and Australia, highlighting the supporting evidence of possible pathogenesis and treatment modalities of CMO in RP. The authors proposed that the likely mechanisms for RP-CMO involved the breakdown of the blood retina barrier (BRB) and / or retinal pigment epithelium pump mechanism failure and / or Muller cells oedema and dysfunction. When the cystoid spaces are located in the inner nerve fibre layer, suggesting that inner BRB has a greater role. The current evidence available for RP-CMO treatment, this is suggestive that topical Carbonic anhydrase inhibitors (CAIs) may be used as a first line treatment but consideration should be given for possible sideeffects and potential rebound phenomenon of CMO. Oral CAIs may be second line option but carry risks of more systemic sideeffects. The authors recommended that large prospective randomised control trials (RCTs) are needed to improve treatment of RP-CMO, to aim to improve short-term vision and slow the rate of vision loss over time.