We are all aware of the major contact lens companies that produce large quantities of soft bifocal and multifocal contact lenses. For a great many patients, these offerings work quite well. However, a fair number of patients require a more customized lens design to meet their needs.
For this group, we are fortunate to have dozens of independent soft and GP contact lens laboratories that are innovators in custom lens designs, with many potential parameter combinations available. There are soft spherical multifocals, soft toric multifocals, and GP multifocals in numerous designs. Which design to utilize comes down to what each particular patient needs.
First, evaluate patients’ motivation to wear a presbyopic contact lens correction. Patients need to understand that presbyopia is a compromise. No contact lens will work 100% of the time. Generally, it is possible to meet about 80% to 90% of their needs.
Second, evaluate patients’ external ocular health. They need to have a reasonably good tear film and tear makeup to comfortably wear contact lenses. Adequate tears also make vision better and more stable. The lids need to be in good apposition to the globe, and the conjunctiva should be white and quiet. The cornea also must be free of keratopathy and other insults.
Contact Lens Considerations
Next, a refraction and keratometry or topography should be performed. These tests allow you to determine the amount, location, and type of any astigmatism. This knowledge will guide your choice of a soft versus a GP design.
If the astigmatism is external, a GP lens is an excellent choice. GP multifocals are available in spherical designs and in toric/bitoric designs for patients who have higher levels of astigmatism. Further, GP lenses can be made in aspheric (front or back), bi-/multi-aspheric, concentric, and translating designs. Aspheric designs are referred to as simultaneous image designs because multiple focal points are presented to the retina at the same time. These are great for patients who work in an office environment and have vision demands at multiple distances. Translating designs, also known as alternating image designs, present distance or near images to the retina separately. They are ideal for patients who have high visual demands at distance and/or near. All of the GP lens offerings are available in a wide range of distance, cylinder, and add powers.
If the astigmatism is internal, or if the patient is GP intolerant, a custom soft multifocal lens may be a better option. These are typically simultaneous image designs, although at least one laboratory produces a translating soft lens. Most custom soft multifocals have an aspheric or concentric design. The bifocal/multifocal zone size can be varied, and the design can be either center-distance or center-near. Astigmatism correction can be placed on the back or front surface in virtually any cylinder power or axis needed.
With the variety of custom GP and soft presbyopic lenses available, any patient who has normal eye health is a potential candidate. If motivation and realistic expectations are there, fit these challenging patients and enjoy the satisfaction of a job well done. CLS