Controlled binocular acuity (CBA)

Controlled binocular acuity is defined and the reference for the reasons behind proposing the new term given. We have proposed the term controlled binocular acuity (CBA)1 to replace binocular visual acuity (BVA). Confusion between vision with both eyes open and vision under binocular control has occurred in the literature across different specialties. Our definition of CBA is: The maximum visual acuity obtainable while maintaining binocular single vision (irrespective of uniocular visual acuity). The first part of the definition is that used in the British Orthoptic Society’s Dictionary of Common Terms2 for BVA. The latter part is contrary to some teaching. A patient may maintain control of a deviation beyond the level of acuity of the weaker eye and so we clarify, in the definition, that the measure we wish to record is the highest acuity during which binocular single vision is maintained, whatever the weaker eye can see.