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Saturday, 31 October 2015

Caution: Some Special-Effect Halloween Contact Lenses Reduce Vision Quality


October 2015 — Special-effect contact lenses (also called theatrical lenses, Halloween contact lenses, and decorative contacts) are a popular choice among costume enthusiasts who want to dramatically alter their appearance, especially at Halloween.
Halloween contact lenses can reduce vision quality.
But beware: According to a new study, some special-effect contacts can interfere with your vision, especially in low-light conditions such as when driving at night or walking after dark.
Researchers investigated changes in visual function of 30 healthy volunteers who wore either clear contact lenses or special-effect contacts with different pigment-free optical zone diameters (in other words, with different sizes of pupil openings in the design). Special-effect lens designs evaluated in the study had clear pupil zone diameters of 4.0, 5.0 and 6.0 millimeters, which are smaller than the natural pupil diameter of relatively young people in low-light conditions.
The study included visual acuity tests with a standard eye chart and measurements of contrast sensitivity and higher-order aberrations.
Results showed that participants who wore special-effect contact lenses with small pupil designs (4 mm clear pupil zone) had significantly reduced visual acuity. Also, higher-order aberrations increased with special-effect designs with small pupil zones, and contrast sensitivity decreased when wearing the decorative lenses (even in normal lighting).
The study authors concluded that people considering purchasing theatrical contact lenses for Halloween and other occasions should be made aware of possible disturbances in visual function these lenses may cause.
Remember, just like conventional (clear or nearly clear) contact lenses that are prescribed for nearsightedness or farsightedness, special-effect contacts must be fitted by an eye care provider, and a contact lens prescription is required to purchase them. Special-effect lenses are available with or without corrective power and therefore can be worn by nearly everyone — including people with naturally perfect vision — for fun and special occasions.