Terminology

If confusion over nomenclature is an indicator of confusion over the subject then CRVO is no different. Leibreich in 1854 first described the clinical appearance of CRVO as ‘retinal apoplexy’1 followed closely by Leber in 1877 who preferred ‘haemorrhagic retinitis’.2 We now use ‘central retinal vein occlusion’ assuming the presence of a blockage of the vein in the optic nerve head. Hayreh coined the phrases ‘venous stasis retinopathy’ for the milder types of CRVO and ‘haemorrhagic retinopathy’ for the more severe disease.3 Similarly, the terms ‘ischaemic’ and ‘non-ischaemic’ CRVO have been employed4 and ‘indeterminate’ used for those cases which did not fit easily into the previous categories.5 Gass has described some eyes as ‘impending, incipient, partial or incomplete’ when patients are asymptomatic or have mild transient visual disturbance.4 ‘Impending’ and also ‘incipient’ tend to suggest a risk of the development of CRVO in the future but a progressive situation which is not part of the natural history of the condition needs to be proved. Do these patients develop an acute CRVO at a future date or do they gradually develop cystoid macular oedema and capillary dropout as is expected in other cases of CRVO? Walsh further classified a mixed group of retinal vein occlusions into primary retinal vein occlusion when there is no systemic disease and secondary CRVO in which systemic disease is present.6These varied terminologies can lead to some confusion—for example, the term ‘venous stasis …