DURING A RECENT hybrid lens workshop, Canadian third-year optometry students posed questions regarding scenarios in which a clinician would choose between hybrid contact lenses and several other lens modalities. Here are three clinical examples.
HYBRID VERSUS SOFT TORIC LENSES
For a first-time contact lens wearer who presents with refractive cylinder close to corneal cylinder, an off-the-shelf toric lens can provide an adequate visual outcome. In-office trials typically max out at –1.75D, but you can order up to –2.75D (even up to –5.75D in some extended ranges).
However, a symptom of higher amounts of astigmatic refractive error is that the vision fluctuates upon blink due to lens rotation, despite stabilization methods built into the lens to keep the optics aligned (Figure 1). A hybrid lens for the regular cornea can be fitted to improve quality of vision for these patients. The GP center provides aspheric optics in addition to tear lens correction to compensate for corneal astigmatism to provide sharp, stable vision.
HYBRID VERSUS CORNEAL GP LENSES
In patients for whom scleral lens wear is contraindicated or has been deemed unnecessary or unsuccessful, the optics of a GP lens are typically still required. During the workshop, the third-year students got to trial hybrid lenses on eye, as they had done for corneal GP lenses the week prior. Hybrid lenses with their silicone hydrogel (SiHy) skirts were repeatedly reported by the students to be “more comfortable than a corneal GP.”
However, students were told that if the patient has visually significant residual astigmatism, a corneal GP would be the best option to fit, as back- and front-surface toric lens parameters can be incorporated during manufacturing. These features are not currently offered with hybrid lenses available in North America.
HYBRID VERSUS SCLERAL LENSES
For newly diagnosed irregular corneal patients, especially those who have mild to moderate keratoconus, the dispersion of the irregularity across the corneal surface is important when determining the best lens design to fit. Hybrid lenses are manufactured with a standard 8.5mm GP center.
For central and paracentral cones that are well-defined and have an apex within 5mm of pupil center (Figure 2), a hybrid lens can be a great option for visual correction. They can be applied and removed with dry fingers, so no additional tools are needed. They are filled with preservative-free saline like sclerals, but have a significantly lesser vault over the corneal surface when best fit. This can potentially yield a higher quality of vision for the patient, as shown in scleral lens studies (Otchere et al, 2018; Villa et al, 2022). If the corneal irregularity extends beyond the mid-peripheral cornea, a scleral lens would be a better choice to obtain a successful contact lens fit because you can vault over the entire area of irregularity. CLS
- Otchere H, Jones L, Sorbara L. The Impact of Scleral Contact Lens Vault on Visual Acuity and Comfort. Eye Contact Lens. 2018 Nov;44 Suppl 2:S54-S59.
- Villa M, Cavas F, Piñero DP. Optical Impact of Corneal Clearance in Healthy Eyes Fitted with Scleral Contact Lenses: A Pilot Study. J Clin Med. 2022 June;11:3424.