unifocal

Unifocal is an adjective describing something that has a single focal point or focus. The term derives from the Latin uni- meaning “one” and focalis meaning “of a focus.” In optics and vision science, a unifocal lens has a single focal length and is designed to form one clear image at a given distance.

In ophthalmology and optometry, unifocal (or single-vision) lenses correct a single refractive error, such as myopia, hyperopia, or simple astigmatism. They provide a single, constant focal distance and do not incorporate separate near or intermediate focal points. This contrasts with multifocal or progressive lenses, which contain multiple focal powers intended to aid both distance and near tasks, such as reading. Unifocal contact lenses or spectacles are commonly prescribed for people who do not require correction for presbyopia or who prefer a straightforward, one-distance solution.

In medical imaging and pathology, unifocal describes a lesion or disease process that is confined to a single location or origin, as opposed to multifocal involvement, which appears in multiple sites. This terminology is used in radiology, oncology, and pathology reports to denote the distribution of a finding, such as a unifocal tumor versus multifocal lesions.

Related terms include bifocal, trifocal, and multifocal. While unifocal is widely used in optics and medical contexts, its exact meaning is sometimes clarified by the field to avoid ambiguity about focal points or lesion distribution.