What is PL in ophthalmology?

"PL" or "Pl" means "Plano." The easy way to understand this is to just think of "zero" when you encounter it in a glasses prescription or in any other assessment of refractive error and vision.

Historically, lens grinders would have a blank piece of glass with parallel front and back surfaces that was to be ground an polished into a prescription lens. Since the surface was flat on both sides, these were known as "plane" or "plano" in Latin. Even though these days are long gone, opticians, optometrists, and ophthalmologists still write "PL" in the first, or spherical part of a lens Rx: e.g. PL -1.50 x 180˚. [The first space is for the spherical component of the lens, the second is for any toric, that is, astigmatism correction, and the 3rd space is the axis in degrees of that astigmatism correction.

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic