SCLERAL LENSES can be challenging for patients and practitioners alike. Among new scleral wearers, a study found, 27% discontinued wear within the first year. The main reasons for discontinuation were handling issues (35%) and discomfort (19%) (Macedo-de-Araujo, 2020). Practitioners are aware of the life-changing benefits sclerals offer, but there’s no “one-size-fits-all” contact lens. Sclerals are not the ideal choice for everyone.

A SAMPLE CASE

A keratoconus patient presented dissatisfied with his vision with glasses. In the last 12 years, he failed with corneal GP lenses, hybrids, and, most recently, sclerals. Although he saw 20/20 when wearing his well-fit 14.9mm diameter scleral lenses, he possessed deep-set eyes and small palpebral fissures, causing him to struggle with lens application.

He presented seeing 20/30 OD and 20/50^-3 OS with a refraction of –3.75 –5.00 x 015 OD and –4.00 –5.00 x 150 OS. His horizontal visible iris diameter was 11.6mm and his corneas were clear without scarring. When we discussed his contact lens history, he said he had worn soft lenses successfully for eight years prior to his diagnosis. After discussing the options of piggybacking versus custom soft lenses, the patient decided he wanted to give custom soft lenses a try.

There are two main custom soft lens designs available for keratoconus: those with an increased central thickness (CT) to mask corneal irregularity and those that employ aspheric optics and a uniform thickness. This patient experienced the best vision utilizing a design that had increased CT. By increasing the CL thickness over the central optic zone, the lens begins to take on the non-flexing nature of a GP and causes irregular astigmatism to become more regular by resulting in smoother keratometry or Placido disc topography mires (Lampa, 2023).

These lenses have two curves: a central base curve with various thickness options and a peripheral lenticularized “fitting curve” to reduce the peripheral lens thickness, enhancing comfort and oxygen transmissibility over the corneal limbus (Andrzejewski, 2020).

The patient was trial fit with diagnostic lenses; the central BC and fitting curve were chosen by averaging the central 3mm simKs from the tomography (Figure 1) and following the manufacturer’s fitting guidelines, starting with an index of thickness (IT) factor of zero (0.35mm thick) and increasing it by an additional 0.1mm until stable, crisp mires were seen on over-topography. Lens movement and rotation were noted and followed by sphero-cylindrical over-refraction.

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To promote appropriate tear exchange, these lenses are expected to move more than typical soft lenses, exhibiting 0.5mm to 1.0mm of movement with the blink, controlled by adjusting the peripheral fitting curve. The fitting curve is flattened if there’s minimal movement or steepened if it’s excessive.

Final parameters were ordered:
OD: 7.8mm BC, 8.4mm fit curve, IT = 0, 15.0mm, –4.00 –2.50 x 005
OS: 7.0mm BC, 8.4mm fit curve, IT = 1, 15.0mm, –5.75 –3.00 x 165.

The patient was thrilled to see 20/20 OD and 20/30⁺² OS with significantly easier lens application and an improved quality of life.

Although GP optics are the usual go-to for patients who have keratoconus and irregular corneas because of their superior optics, custom soft lenses can be a game-changer. Practitioners should carefully assess the needs and limitations of patients before recommending a contact lens modality. CLS

References

1. Macedo-de-Araújo RJ, van der Worp E, González-Méijome JM. A one-year prospective study on scleral lens wear success. Cont Lens Anterior Eye. 2020 Dec;43:553-561.
2. Lampa M. Custom soft lenses for irregular astigmatism. Rev Optom. 2023 Aug 15.
3. Andrzejewski T. Managing irregular corneas with soft lenses. Rev Cornea Contact Lens. 2020 Feb 15.