Learn about the three options available for these patients

Rigid multifocal contact lenses can be an option for patients who have significant degrees of corneal astigmatism and, thus, cannot achieve from a soft contact lens the consistency and quality of vision these patients require. This may occur due to several factors, such as inconsistent lens orientation, tear film deficiency, and corneal irregularity, secondary to pathology or trauma. That said, so that reality meets with expectation, patients should be educated that rigid multifocal contact lenses will not provide impeccable vision for every undertaking. Additionally, patients should be told that these contact lenses will not offer VA equivalent to that of spectacles for all wearers.

Here, I discuss the rigid gas permeable (RGP) contact lens options for these patients.

ASPHERIC RGPs

These contact lenses, which contain “simultaneous vision” optics, can be ideal for refitting current RGP wearers, as little-to-no adaptation is required. Additionally, aspheric contact lenses are indicated for patients who have significant intermediate distance needs.

The add power in “simultaneous vision” aspheric contact lenses is achieved by manufacturing aspheric curves on one or both contact lens surfaces. Higher add powers may also be generated in some designs by adding peripheral plus power to the periphery of the front surface of the contact lenses.

Fitting pearl. Aspheric contact lenses are customarily fit on K or slightly steeper, depending upon the eccentricity of the posterior curve. Best vision and comfort are achieved with a slightly superior central positioning “lid attached” fit. Thus, ODs should aim for an alignment fit that has a low-to-moderate edge lift. I find that aspheric multifocal contact lenses can successfully correct up to 3.00 D of corneal astigmatism. Alternative designs should be considered, however, if good centration cannot be achieved or the corneal toricity extends from limbus to limbus.

GUIDE TO LENS SELECTION

LENS DESIGN	PATIENT CANDIDATE	FITTING TIPS
SIMULTANEOUS	New or current RGP wearer. Refractive cylinder equal to corneal cylinder and < 3.00 D. Significant intermediate distance demands. Pupil size between 3 mm and 5 mm.	Lid attachment. Good centration. Overplus non-dominant eye slightly, if needed. Avoid on high against-the-rule corneas. Ensure slight lens “translation” on downgaze.
SEGMENTED (TRANSLATING)	Current GP wearer. Residual astigmatism > 1.00 D (can fit anterior toric). High near and/or close vision demand. Smaller or larger-than-average pupil size. Lower lid margin positioned at or slightly lower than inferior limbus.	Distance optics centered over pupil. Reading segment aligned with lower pupillary margin. Good “translation” in downgaze.
SCLERALS	Irregular astigmatism, ocular surface disease, post-refractive surgery.	Avoid when best-corrected distance acuity is compromised. Optimize fit before adding multifocal optics.

SEGMENTED RGPs

Segmented in bifocal or trifocal, “alternating” contact lenses can be successful for patients who require optimum vision at distance and/or near, and for patients who have more significant (2.50 D or more) corneal and/or residual astigmatism.

These contact lenses can be manufactured with back-surface, bitoric, or front-surface optics. They are stabilized and engaged by the lower lid with either a prism ballast or prism-plus truncation.

Fitting pearl. Because segmented RGPs are stabilized and engaged by the lower lid with either a prism ballast or prism-plus truncation, it’s important optometrists ensure the patient’s lower lid lies at the lower limbus. The add power in segmented bifocals is “accessed” via the upward excursion of the contact lens (“translation”), as the eye moves downward into the reading position. When fitting bilateral translating bifocals, intermediate vision may be enhanced through a “modified monovision” approach by overplussing the distance segment in the non-dominant eye.

SCLERALS

Although the multitude of proprietary laboratory brands in the presbyopia RGP category fall into either aspheric or segmented, multifocal scleral contact lenses can also be an option for these patients. Specifically, a growing number of scleral lens laboratories, including those that supply diagnostic, empiric, and impression-based technology, offer designs that incorporate simultaneous vision optics. Several of these manufacturers customize the add zones and decenter the optics to compensate for contact lens decentration or large-angle Kappa.

Fitting pearl. When contemplating multifocal scleral fitting, I suggest the OD fit for best distance vision first and then incorporate the multifocal optics. The reason: This allows the optometrist to assess the patient’s tolerance for the possible slight compromise in visual quality of multifocal scleral lenses.

GETTING STARTED

I have found that empirical fitting is an efficient and effective approach to fitting most RGP multifocal designs. Highly trained and knowledgeable consultants available from the manufacturers of these contact lenses can be a great resource in assisting in the design of the first pair of contact lenses. Other advantages of working with these consultants include the ability to optimize the patient’s first wearing experience and avoiding in-office disinfection and storage of trial contact lenses.

Our clinical toolbox is well equipped to satisfy the growing population of presbyopic RGP contact lens wearers. With careful diagnostic evaluation, recognition of patient expectations, and knowledge of contact lens design, ODs can confidently embrace multifocal fitting for presbyopic patients who have astigmatism. OM

DR. RESNICK is president and managing partner at Drs. Farkas, Kassalow, Resnick, and Associates, a contact lens and anterior segment specialty practice in New York. She is a diplomate in the Cornea, Contact Lens, and Refractive Technology section of the AAO, a diplomate of the ABO, and a fellow of the Scleral Lens Education Society.