Strong SA, et al. - Authors assessed whether an association existed between the spatial distribution of cystoid spaces in retinitis pigmentosa-associated cystoid macular oedema (RP-CMO) and carbonic anhydrase inhibitors (CAIs) response. Results demonstrated inner nuclear layer (INL) fluid to be the most common spatial distribution of RP-CMO. Nonetheless, coexisting outer nuclear layer (ONL) fluid on their pretreatment OCT scans was demonstrated by the patients who were classed as a ‘responder’ to CAI treatment. CAIs having better access to retinal pigment epithelium basolateral membrane could explain this compared to neurosensory retina. A minimal impact on response to CAIs by ERM was also demonstrated in the results.