Focus Dailies Toric lenses are designed to correct a common refractive error known as astigmatism. Regular astigmatism occurs due to the irregular shape of the cornea. The cornea is the transparent medium covering the visual pathway allowing light to enter the eye for the process of vision to occur. If the cornea is irregular in shape, meaning less spherical and more elliptical in design, the light entering the eye will focus at two different meridians causing vision to blur. To correct this problem, toric contacts, such as Focus Dailies redirect light to allow these differing focal points to converge and present a clear image to the retina.
Unlike spherical contacts, toric lenses are weighted, known as prism-ballasting, to orient the correction in each meridian at right angles stabilizing the lens and allowing this process to take place. The fit and design of this correction is critical for clear, crisp vision. Spherical contacts have the same power in any meridian of the lens. As the lens rotates during the course of blinking, the visual acuities of the patient will not be compromised since positioning of the correction is not required.
Focus Dailies Toric lenses are designed employing several methods to provide the clearest vision possible for astigmatic patients. When determining the fitting parameters of a toric lens, the eyecare professional will observe the rotational recovery rate of the lens. This simply means that when a toric contact patients blinks the lens will have a tendency to shift slightly potentially compromising visual acuity.
The eyecare professional will select a lens with minimal rotational recovery taking into account the patients anatomical and ocular needs. Focus Dailies Toric lenses were designed with scribe marks at intervals of 0°, 90°, 180° or 270°, depending on the orientation of the lens to allow the fitting process to be more easily observed by the doctor and ease of insertion by the patient.
These lenses also possess a toric back surface design minimally closing the vertex distance, the distance between the surface of the cornea and corrective lens, to allow sharper visual acuities through virtual elimination of off axis astigmatism. Since these lenses are aspheric in design, they bring better comfort to the patient by maintaining an constant thickness across the sagittal value of the lens. This allows the lens to maintain a certain level of comfort enjoyed by the patient not typically associated with conventional planned replacement toric lenses.
Since Focus Dailies lenses are disposable lenses, minimal effort is required of the patient to maintain the hygienics of the lens. At the end of the day, the patient will simply dispose of the contact. This also prevents the buildup of protein deposits associated with conventional planned replacement lenses. Protein deposits are formed when a lens is not cleaned properly and long protein strands begin to adhere to the lenses surface eventually creating a deposit. If left in place for a long period of time, these deposits can have an adverse affect on the cornea, altering its shape and inducing irregular astigmatism significantly compromising visual perception.