Specialty Lenses and Corneal Disease: Part I

By Ashley Tucker, OD, FAAO, FSLS, Dipl ABO

Specialty contact lenses (ie, rigid gas permeable [RGP] lenses, scleral lenses, and hybrid lenses) are a great option for patients who cannot refract well or see well out of spectacles. The goal behind fitting specialty lenses is twofold: 1) to not cause additional harm or compromise to the patient’s cornea, and 2) to provide better vision. Part one of this article by Ashley Tucker, OD, FAAO, FSLS, DIPL ABO, offers direction on selecting the appropriate lens based on patient needs and corneal conditions.

GENERAL SPECIALTY LENS FITTING
When you have a patient with confirmed corneal disease in your chair, first, find out their goal. Some patients do not want to wear contact lenses and can get good vision simply with an updated refraction. But if this is not possible and the patient desires better vision, then specialty contact lenses may be the best option for them.

Next, assess the patient’s corneal health. (Some corneas are not ready for specialty lens wear, such as those with inappropriate endothelial cell count or severe ocular surface disease.) The key challenge is ensuring the chosen lenses do not exacerbate existing corneal conditions. For example, in the case of a condition such as Fuchs dystrophy with corneal edema, careful lens selection is critical to avoid worsening the disease. For a patient with keratoconus and a very thin cornea, ensure the chosen lens does not bear down on the cornea and compromise it further (Figure 1).  

Figure 1. Fluorescein staining showing a scleral lens with bearing on the inferior cornea.

LENS SELECTION
RGP Lenses
These are the original specialty lens, offering great value for patients with mild to moderate corneal irregularities. While not as popular as newer options, RGP lenses are still a viable solution for conditions such as mild keratoconus and are often more affordable than other options.

Scleral Lenses
Scleral lenses are becoming the standard of care for more complex or irregular corneas. These lenses provide a variety of lens options to create the best vision and comfort to patients. For example, these lenses can be customized to accommodate a variety of corneal conditions, including toric, multifocal, and higher-order aberration correction, providing superior vision and comfort for many patients.

Hybrid Lenses
Hybrid lenses combine the comfort of soft lenses with the visual clarity of rigid lenses (Figure 2). Thus, they are a great option for patients who are accustomed to wearing soft lenses but need a rigid lens to achieve the best vision, or for patients who struggle with the insertion and removal process that comes with scleral lens wear.

Figure 2. Hybrid lens fit assessed with fluorescein staining.

FITTING SPECIFICS
Specialty lenses are typically fit either diagnostically or empirically. When fitting RGP and hybrid lenses many practitioners, including myself, prefer the empirical approach, in which topography and refraction data are sent to a lab to create custom lenses. This method provides a higher degree of customization and a quicker fitting process. Practitioners can fit scleral lenses diagnostically, with a fitting set, finding a lens that fits well, doing an overrefraction, etc; using a scleral profilometer, or scleral topographer, which is basically a scan of the entire ocular surface that is sent to a lab, then returned as a trial lens that usually fits well and provides good vision; or by employing impression-based lenses to create a precise mold of the eye, which is sent to the lab to have a custom lens printed.

FROM FIT TO FOLLOW-UP
Specialty lenses are a crucial option for patients with corneal diseases that cannot be managed with traditional eyeglasses. By selecting the appropriate lens type and using the right fitting approach, optometrists can help patients achieve better vision while preserving corneal health. Ongoing assessments and adjustments during follow-up visits are essential to ensure the success of the fit and patient satisfaction.

ASHLEY TUCKER, OD, FAAO, FSLS, DIPL ABO

• Optometrist, Bellaire Family Eye Care, Bellaire, Texas
• Adjunct Faculty, University of Houston College of Optometry, Houston, Texas
• ashley.w.tucker@gmail.com
• Financial disclosure: None acknowledged

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