Astigmatism in a patient’s prescription influences practitioners’ choices when deciding on a contact lens design. Soft lenses are now available in expanded parameters that can correct mild-to-moderate amounts (–0.75D to –2.25D) of astigmatic refractive error with daily disposable lenses or for patients who need multifocal optics. But soft lens availability is greatly reduced when a patient’s astigmatic refractive error exceeds –2.25D, and this level of astigmatism makes it even more important and challenging to avoid the relatively larger refractive errors secondary to lens rotation.
Made-to-order soft monthly replacement lenses and scleral lenses can be successful when standard soft lenses aren’t an option and corneal GPs fail.
A 58-year-old female patient who had a refraction of OD –0.50 –3.25 x 100, 20/20 and OS –1.00 –2.25 x 082, 20/25 was interested in contact lenses for distance and near vision. The higher astigmatism of the right eye limited her soft lens options.
We decided to try monovision in a monthly replacement lens modality. An extended-range soft toric lens with parameters of 8.7mm base curve, 14.5mm diameter, –0.50 –3.25 x 100 in the right eye and a spherical soft lens with parameters of 8.7mm base curve, 14.0mm diameter, +1.00 –2.25 x 080 in the left eye were dispensed. The lenses fit well without rotation and provided visual acuity of 20/20 OD and J1 OS. The patient was satisfied with both comfort and fit. The relatively recent availability of made-to-order monthly replacement lenses in extended ranges provides an additional option for patients who have high astigmatism and would otherwise need to wear a three-month or annual-replacement lens design.
A 26-year-old male who had a refraction of OD +0.25 –4.25 x 018, 20/20 and OS +1.00 –3.75 x 073, 20/20 had failed in soft and scleral lenses because of poor vision. Corneoscleral topography showed paralimbal and scleral toricity (OD 369µm, OS 191µm) that aligned with the toric refractive axis.
The patient was fit with free-form scleral lenses in parameters of OD 16.5mm diameter, –2.50DS, 20/20 and OS 16.5mm, –1.50DS, 20/20. It can be speculated that his previous scleral lenses weren’t matching his significant scleral toricity, leading to decentration and poor vision. Properly aligning the landing zones based on the topography provided this patient with improved vision.
A 48-year-old female patient who had a refraction of OD +1.25 –4.25 x 005, 20/20 and OS +1.25 –4.75 x 162, 20/20 had recently failed corneal GP lenses after 20 years of wear because of increasingly worsening comfort; she subsequently failed with soft contact lenses due to poor vision. Corneoscleral topography showed paralimbal and scleral toricity (OD 762µm, OS 746µm) that aligned with the toric refractive axis.
Scleral lenses with customized toric landing zones were manufactured with spherical power (Figure 1). An over-refraction of the lenses, which had ideal landing zone alignment, revealed a mild amount of residual astigmatism. Final powers were OD –1.00 –1.50 x 005, 20/20 and OS –1.00 –1.25 x 155, 20/20. Front-surface toricity can be added to fully correct refractive error, as the lenses are stabilized by the toric landing zones. CLS