Nystagmus is an involuntary rhythmic oscillation of the eyes, which leads to reduced visual acuity due to the excessive motion of images on the retina. Congenital presentations appear in the first year of life but may also present later as an acquired defect. Low vision or conditions that cause visual deprivation early in life, such as albinism, congenital cataracts, optic nerve hypoplasia, and retinal dystrophies, are associated with congenital nystagmus (CN) (Abel, 2006). This article reviews the benefits of contact lens wear in children who have CN.

Children who have CN have anatomical abnormalities resulting in macular and optic nerve problems and often have refractive error. Due to continuous eye movements in these kids, looking through the optical center of glasses is difficult. This, in turn, induces peripheral prismatic effects, causing visual distortion.

Visual acuity is further reduced by the change in magnification induced by spectacles that degrade image quality and may prevent fusion. Moving the refractive correction closer to the eye decreases the aforementioned optical problems and provides a clearer retinal image. Well-defined images can lead to improvement of fusion and fixation, better control of abnormal eye movements, longer foveation time, and eventually improved vision (Abel, 2006).

Contact lenses improve vision in patients who have CN. Since contact lenses move with the eyes during involuntary movements, children can fixate for a longer time on the visual axis, leading to longer foveation time. Also, by removing the peripheral prismatic effect of spectacles, contact lenses can decrease chromatic and spherical aberrations, reduce the minification/magnification effects of spectacles, decrease aniseikonia, and enhance the visual field (Rutner and Ciuffreda, 2005; Allen and Davies, 1983; Biousse et al, 2004).

It has also been suggested that contact lens wear may dampen nystagmus by decreasing its amplitude and frequency. This phenomenon might be due to sensory feedback from movement of the edge of the lens against the inside of the lids as the eyes oscillate (Allen and Davies, 1983; Biousse et al, 2004; Bagheri et al, 2017).

A Case in Point

Consider a 13-year-old Caucasian female who had a history of CN, retinopathy of prematurity, and degenerative myopia. This young patient presented with vision of 20/200 and 20/150 wearing a spectacle prescription of –11.25 –3.00 x 180 and –10.75 –3.00 x 180 in the right and left eyes, respectively. Due to her degenerative myopia and CN, her referring pediatric ophthalmologist wanted her to be fitted into GP optics in hopes that this would improve her vision. This patient was successfully fitted into scleral lenses that improved not only her visual quality, but also her visual acuity to 20/100 and 20/80 in the right and left eyes, respectively (Figure 1).

Summary

CN substantially impacts visual functioning in children. With eyes that never rest, spectacles are suboptimal either for refractive correction or for mitigating the other deleterious effects of nystagmus. Contact lenses are optically superior in this situation and move with the eyes, thereby providing clearer retinal images than spectacles in children who have nystagmus. There may also be a mechanical cue with contact lens wear that dampens nystagmic eye movements. CLS

References:

1. Abel LA. Infantile nystagmus: current concepts in diagnosis and management. Clin Exp Optom. 2006 Mar;89:57-65.
2. Rutner D, Ciuffreda K. Soft contact lenses to improve motor and sensory function in congenital nystagmus—a case study. J Behav Optom. 2005 Jan;16:17-20.
3. Allen ED, Davies PD. Role of contact lenses in the management of congenital nystagmus. Br J Ophthalmol. 1983 Dec;67:834-836.
4. Biousse V, Tusa RJ, Russell B, et al. The use of contact lenses to treat visually symptomatic congenital nystagmus. J Neurol Neurosurg Psychiatry. 2004 Feb;75:314-316.
5. Bagheri A, Abbasi H, Tavakoli M, Sheibanizadeh A, Kheiri B, Yazdanai S. Effect of Rigid Gas Permeable Contact Lenses on Nystagmus and Visual Function in Hyperopic Patients with Infantile Nystagmus Syndrome. Strabismus. 2017 Mar;25:17-22.