Periodic alternating nystagmus consists of involuntary oscillations of the eyes with cyclical changes of nystagmus direction. It can occur during infancy (e.g. idiopathic infantile periodic alternating nystagmus) or later in life. Acquired forms are often associated with cerebellar dysfunction arising due to instability of the optokinetic-vestibular systems. Idiopathic infantile periodic alternating nystagmus can be familial or occur in isolation; however, very little is known about the clinical characteristics, genetic aetiology and neural substrates involved. Five loci (NYS1-5) have been identified for idiopathic infantile nystagmus; three are autosomal (NYS2, NYS3 and NYS4) and two are X-chromosomal (NYS1 and NYS5). We previously identified the FRMD7 gene on chromosome Xq26 (NYS1 locus); mutations of FRMD7 are causative of idiopathic infantile nystagmus influencing neuronal outgrowth and development. It is unclear whether the periodic alternating nystagmus phenotype is linked to NYS1, NYS5 (Xp11.4-p11.3) or a separate locus. From a cohort of 31 X-linked families and 14 singletons (70 patients) with idiopathic infantile nystagmus we identified 10 families and one singleton (21 patients) with periodic alternating nystagmus of which we describe clinical phenotype, genetic aetiology and neural substrates involved. Periodic alternating nystagmus was not detected clinically but only on eye movement recordings. The cycle duration varied from 90 to 280 s. Optokinetic reflex was not detectable horizontally. Mutations of the FRMD7 gene were found in all 10 families and the singleton (including three novel mutations). Periodic alternating nystagmus was predominantly associated with missense mutations within the FERM domain. There was significant sibship clustering of the phenotype although in some families not all affected members had periodic alternating nystagmus. In situ hybridization studies during mid-late human embryonic stages in normal tissue showed restricted FRMD7 expression in neuronal tissue with strong hybridization signals within the afferent arms of the vestibulo-ocular reflex consisting of the otic vesicle, cranial nerve VIII and vestibular ganglia. Similarly within the afferent arm of the optokinetic reflex we showed expression in the developing neural retina and ventricular zone of the optic stalk. Strong FRMD7 expression was seen in rhombomeres 1 to 4, which give rise to the cerebellum and the common integrator site for both these reflexes (vestibular nuclei). Based on the expression and phenotypic data, we hypothesize that periodic alternating nystagmus arises from instability of the optokinetic-vestibular systems. This study shows for the first time that mutations in FRMD7 can cause idiopathic infantile periodic alternating nystagmus and may affect neuronal circuits that have been implicated in acquired forms.

PurposeTo report outcome, complications and safety of retropupillary fixated iris-claw intraocular lenses in a pediatric population.DesignRetrospective study.Patients and MethodsTen consecutive pediatric patients (15 eyes) underwent placement of retropupillary fixated iris-claw intraocular lenses between October 2007 and July 2013 at the Department of Ophthalmology, Medical University Graz and General Hospital Klagenfurt, Austria. Postoperative visual acuity and complications were analyzed.ResultsMedian final best-corrected visual acuity improved by 0.12 logMAR from preoperative baseline. Mean postoperative spherical equivalent was -0.05 ± 1.76 D. No serious complications were observed intra- or postoperatively during the entire follow-up period of up to 40 months. One patient experienced a haptic disenclavation with IOL subluxation immediately after a car accident.ConclusionOur study demonstrates that iris-claw intraocular lens implantation behind the iris is safe in children with lack of capsular support and yields excellent visual outcome with low complication rate.

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An 11-year-old previously healthy boy was referred to the pediatric department with impaired vision after an episode of fever and vomiting. Ophthalmologic examination revealed bilateral mydriasis, with a reduced pupillary response to light and accommodation (Figure). Diluted norepinephrine (0.1%) was instilled in both eyes, which elicited supersensitive dilatation of the pupils bilaterally owing to reinnervation and upregulation of the postsynaptic receptors, consistent with tonic pupils. Uncorrected Snellen visual acuity was 20/32 OU for distance and 20/200 OU for near. Ocular motility was normal. Results of slitlamp examination and ophthalmoscopy showed no abnormalities.Results of complete blood cell counts, serum chemistry examination, cerebrospinal fluid examination, and virologic studies of blood and stool performed for exclusion of infection were all negative. Tumor, aneurysm, or traumatic lesion were excluded by cranial magnetic resonance imaging. Serum GQ1b ganglioside IgG antibodies associated with internal ophthalmoplegia in Fisher syndrome were not detected.Within the following 2 weeks, progressive generalized autonomic dysfunction developed including reduced food intake and weight loss, constipation, urinary retention, anhidrosis, xerostomia, and xerophthalmia. Ophthalmologic reexamination showed unaltered pupillary abnormality. Results of Schirmer test without topical anesthesia showed 0 mm of tear production. Lissamine green staining of the exposed interpalpebral areas showed moderate changes of the conjunctiva. Mild corneal staining was evaluated with cobalt blue illumination after fluorescein instillation. Artificial tears and ointment were initiated to treat the aqueous tear deficiency. Figure. Bilateral mydriasis with a reduced pupillary response to light and accommodation in an 11-year-old boy. WHAT WOULD YOU DO NEXT? A. Prescribe phototropic variofocal glasses B. Start pilocarpine eyedrops C. Obtain blood sample to investigate for autoimmune autonomic ganglionopathy D. Recommend genetic testing Clinical Review & Education