This prospective study found that handheld spectral domain optical coherence tomography (SD-OCT) is highly sensitive and specific in classifying foveal abnormalities in infantile nystagmus.
Subjects included 50 patients with nystagmus and 50 healthy controls (mean age, 3.2 years; range, 0–8 years). The researchers scanned each patient using handheld SD-OCT (Bioptigen Inc.) without sedation and classified their foveal morphology as the following: (1) typical foveal hypoplasia (predicting clinical diagnosis of albinism, PAX6 mutations, or isolated foveal hypoplasia); (2) atypical foveal hypoplasia (predicting achromatopsia); (3) other foveal changes (corresponding to retinal dystrophies); or (4) normal fovea (predicting idiopathic or manifest latent nystagmus).
Handheld SD-OCT was successful in 94 percent of examinations. Of the 23 patients with typical foveal hypoplasia, 21 were diagnosed with albinism and two with PAX6 mutations. Five patients were classified as atypical and diagnosed with achromatopsia. Six patients had other abnormal foveal morphology and were diagnosed with retinal dystrophy. Sixteen patients had normal foveal morphology, of which 12 were diagnosed with idiopathic nystagmus and four with manifest latent nystagmus.
Sensitivities of handheld SD-OCT for classifying typical or atypical foveal hypoplasia, other abnormal foveal morphology, and normal morphology were 92.8 percent, 86.7 percent, 41.1 percent and 88.4 percent, respectively, with specificities of 91.4 percent, 94.8 percent, 97.7 percent and 95.1 percent, respectively.
The authors note that image acquisition was highly successful and quick, taking two to five minutes in cooperative children and up to 20 minutes in less cooperative children. Image acquisition in children aged between 1 and 2 years was the most challenging.
They write that an interesting result in this study was that patients with neurologic syndromes (e.g., microcephaly) had foveal abnormalities consistent with retinal dystrophy. Examination of further patients will be helpful to characterize the fovea in children with neurologic syndromes.
They conclude that by identifying diagnostic clues, such as typical and atypical foveal hypoplasia or the presence or absence of other foveal morphologic abnormalities, further investigations can be prioritized, thereby resulting in a timelier and more definitive and cost-effective underlying diagnosis.