High myopia (> –5.00D) is on the rise such that 900 million cases are expected by 2050 (Holden et al, 2016). The excessive axial elongation in high myopia results in retinal stretching, detachment, photoreceptor reorganization, and chorioretinal atrophy. While any of these may reduce visual acuity, the minification caused by spectacles surely impairs vision in high myopia (Vincent, 2017).
In highly myopic children, contact lenses provide a larger retinal image and a greater field of vision and fixation (Vincent, 2017). The lenses also positively impact self-esteem, self-worth, confidence, and social acceptance, and they promote sports participation in children (Walline et al, 2009).
Why GPs for High Myopia?
GP lenses offer a number of benefits when fit for high myopia in children. One benefit is that practitioners have a wide variety, and complete control over, the lens parameters. Additionally, lenses are quickly manufactured and are easily verified and reproduced.
Moreover, GP lenses have excellent optics. For example, spherical GP lenses can mask several diopters of both regular and irregular astigmatism. Despite the high power and thickness of high-minus lenses, GP lenses have good oxygen transmissibility (Dk/t) and can be manufactured in any high-Dk material. Therefore, hypoxic stress to the cornea is less likely to be an issue compared to wear of hydrogel soft contact lenses (Sindt, 2006).
In contrast to soft lenses, the rigidity of GP lenses is easier to handle because the lenses do not fold over during application and removal. Because GP lenses are resistant to dehydration, fit and power are more stable, and less variable, in comparison to soft lenses (Sindt, 2006). Furthermore, GP lens materials offer ultraviolet protection and have a decreased risk of contact lens-related adverse events, such as microbial keratitis, papillary conjunctivitis, and corneal neovascularization (Key, 1990; Keay et al, 2006).
A Case in Point
Consider a case of a 12-year-old boy who has high myopia and astigmatism. He wanted to play basketball, but was shy and unsure because of his thick spectacle prescription (Figure 1). This patient had a manifest refraction of –18.00 –2.50 x 180 and –17.50 –2.50 x 180, with a visual acuity of 20/60 and an axial length of 30.5mm in both the right and the left eyes.
The patient opted to be fitted into a scleral GP lens with a front-surface center-distance +3.00D add multifocal for myopia control (Figure 2). With GP lens correction, his vision improved to 20/30 in both the right and the left eyes, and he made the basketball team.
In highly myopic children, GP lenses are superior to spectacles and offer benefits not available in soft lens modalities. High myopia is increasingly prevalent, and we, as eyecare providers, are best positioned to improve patients’ lives by prescribing GP lenses. CLS
For references, please visit www.clspectrum.com/references and click on document #265.