27th December 2023

Use of a pinhole device

Where monocular diplopia is confirmed, a pinhole device should be utilised to identify whether the cause may be related to anterior structures such as the cornea or the lens. The pinhole will block peripheral light rays, only allowing central light to pass through the cornea and pupil, improving acuity and eliminating diplopia secondary to an optical cause. If the diplopia persists, one should consider issues with the macula, such as oedema or problems with the cortex. The symptom of multiple images (> 2) is known as cerebral polyopia and is a rare occurrence of monocular diplopia secondary to structural disorders of the cerebral cortex.