Until 2021, contact lens multifocal technology has not offered optimization of the multifocal design that accounts for pupil size changes occurring with both age and magnitude of refractive error.
Although it is widely understood that pupil size decreases with age, contact lens manufacturers usually offer up to 3 optic zone designs that differ based on the near add power. Traditional optic zones have typically been “one size fits most” with a standard optic zone size across all refractive powers at distance. 5 Evidence has shown that younger, more myopic patients generally have larger pupils compared with older hyperopic patients who likely have smaller pupils. In addition to pupil size constricting with age, note that research has demonstrated that pupil sizes differ because of refractive error. If a patient’s pupil is too small or too large compared with the optic zone, it can negatively affect the visual potential. The science behind centering and balancing the optic zone over the pupil area is an important factor that can influence best-corrected visual acuity. As with most multifocal contact lenses, the optical zone must be centered and aligned with the pupil to work efficiently. Other than bifocal or progressive glasses, multifocal contact lenses provide a great nonsurgical option for the treatment of presbyopia. Pupil-optimized technology in contact lenses Pupil size is an important consideration when selecting treatment options for presbyopia, including multifocal contact lenses, refractive surgery options, and/or pharmacological options. 3 The pupil response involves reflexive and voluntary actions, and the size of a patient’s pupils can affect the levels of chromatic and spherical aberration experienced, which ultimately influences the subjective visual perception. It is important to note that other factors can also influence overall pupil size, including luminance, retinal sensitivity, central cognitive processes, alertness, emotional unrest, and refractive error. ✺ccommodation, the steepening curvature of the crystalline lens when looking at a near object and the flattening of the lens to focus on distant objects » Vergence, the inward rotation of the eye when looking at near stimulus and the outward rotation when looking far away 1 The pupil response at near is thought to help increase depth of field for near vision across a wider range with a smaller pupil compared with a large pupil. Pupil constriction in response to light and near fixation decreases the amount of crystalline lens exposed, presumably increasing depth of field and improving visual acuity. The pupil response at near is part of the 3 eye movements, referred to as the near triad, that usually (but not always) occur together. The pupil is controlled by opposing iris muscles-when the iris sphincter contracts, the pupil constricts when the iris dilator muscle contracts, the pupil dilates. Pupil size is influenced by the parasympathetic (constriction) pathway and the sympathetic (dilation) pathway. 1,2 The importance of pupil size and limitations in human anatomy have inspired the shift in focus to a multitude of procedures, surgeries, and pharmaceutical options to correct presbyopia. These are some of the first signs of presbyopia. With age, commonly from 40 to 65 years, a loss of accommodative function is expected, which results in patients requiring more light to read, squinting to see near objects, and holding reading materials farther away.
Pupil size during a given moment is affected by several factors and influences how much light reaches the retina. The pupil, an important transparent opening of the eye, is responsible for controlling the amount of light that passes through the surface of the lens it exposes.
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