Purpose.: Nystagmus, which can be infantile (congenital) or acquired, affects all ages. The prevalence of nystagmus in the general population is unknown. New genetic research and therapeutic modalities are emerging. Previous estimates have been based on wider ophthalmic epidemiologic studies within specific occupational or age groups. The authors carried out the first epidemiologic study to specifically establish the prevalence of nystagmus in Leicestershire and Rutland in the United Kingdom. Methods.: Three independent data sources identified persons with nystagmus from the hospital and community. The first was a hospital-based questionnaire and clinical survey (n = 238). The visually impaired services (n = 414) and education services (n = 193) in Leicestershire provided the second and third separately obtained community-based sources of information. Capture-recapture statistical analysis was used to estimate prevalence. Results.: The prevalence of nystagmus in the general population was estimated to be 24.0 per 10,000 population (95% confidence interval [CI], ±5.3). The most common forms of nystagmus were neurologic nystagmus (6.8 per 10,000 population; 95% CI, ±4.6), nystagmus associated with low vision such as congenital cataracts (4.2 per 10,000; 95% CI, ±1.2), and nystagmus associated with retinal diseases such as achromatopsia (3.4 per 10,000 population; 95% CI, ±2.1). Within ethnic groups, nystagmus was significantly more common in the white European population than in the Asian (Indian, Pakistani, other Asian backgrounds) population (P = 0.004). Conclusions.: The findings suggest that nystagmus is more common in the general population than previously thought. This may be of significance in resource allocation and health care planning.

Research from JAMA Ophthalmology — Risk Factors and Genetics in Common Comitant Strabismus — A Systematic Review of the Literature

Idiopathic infantile nystagmus (IIN) is a genetically heterogeneous disorder, often associated with FRMD7 mutations. As the appearance of the retina is reported to be normal based on conventional fundus photography, IIN is postulated to arise from abnormal cortical development. To determine whether the afferent visual system is involved in FRMD7 mutations, we performed in situ hybridization studies in human embryonic and fetal stages (35 days post-ovulation to 9 weeks post-conception). We show a dynamic retinal expression pattern of FRMD7 during development. We observe expression within the outer neuroblastic layer, then in the inner neuroblastic layer and at 9 weeks post-conception a bilaminar expression pattern. Expression was also noted within the developing optic stalk and optic disk. We identified a large cohort of IIN patients (n = 100), and performed sequence analysis which revealed 45 patients with FRMD7 mutations. Patients with FRMD7 mutations underwent detailed retinal imaging studies using ultrahigh-resolution optical coherence tomography. The tomograms were compared with a control cohort (n = 60). The foveal pit was significantly shallower in FRMD7 patients (P < 0.0001). The optic nerve head morphology was abnormal with significantly decreased optic disk area, retinal nerve fiber layer thickness, cup area and cup depth in FRMD7 patients (P < 0.0001). This study shows for the first time that abnormal afferent system development is associated with FRMD7 mutations and could be an important etiological factor in the development of nystagmus.