Valeria L. N. Fu

Visual Acuity Development of Children with Infantile Nystagmus Syndrome

PURPOSE Infantile nystagmus syndrome (INS) can be idiopathic or associated with ocular or systemic disease. The ocular oscillation of INS directly contributes to loss of visual acuity. In this study, visual acuity development in patients with INS was examined. METHODS Children with INS were classified as having idiopathic INS (n = 84) or INS with an associated sensory deficit: INS and albinism (n = 71), bilateral optic nerve hypoplasia (ONH; n = 23), or congenital retinal disorder (n = 36). Visual acuity was assessed with Teller cards and/or optotypes, and the data were analyzed for three age groups (<24 months, 24-48 months, and >48 months). RESULTS Patients with idiopathic INS showed mildly reduced visual acuity early in life and gradual maturation with age that paralleled a normative curve. Patients with albinism also showed a mild visual deficit early in life but failed to keep pace with the normative curve, showing a gradual increase in visual acuity deficit. Patients with ONH and congenital retinal disorders exhibited more severe visual acuity deficits during infancy. The ONH group displayed slow improvement of visual acuity with a plateau at 24 months through >48 months, with a small increase in visual acuity deficit. The congenital retinal disorder group had no significant change in visual acuity across age and had a rapid increase in visual acuity deficit. CONCLUSIONS The pattern of visual acuity development differs among children with INS, depending on the presence or absence of associated sensory system deficits. Careful characterization of visual system differences in patients with INS is important if visual acuity is an outcome in clinical trials.

Quantifying Nystagmus in Infants and Young Children: Relation between Foveation and Visual Acuity Deficit

PURPOSE Nystagmus eye movement data from infants and young children are often not suitable for advanced quantitative analysis. A method was developed to capture useful information from noisy data and validate the technique by showing meaningful relationships with visual functioning. METHODS Horizontal eye movements from patients (age 5 months-8 years) with idiopathic infantile nystagmus syndrome (INS) were used to develop a quantitative outcome measure that allowed for head and body movement during the recording. The validity of this outcome was assessed by evaluating its relation to visual acuity deficit in 130 subjects, its relation to actual fixation as assessed under simultaneous fundus imaging, its correlation with the established expanded nystagmus acuity function (NAFX), and its test-retest variability. RESULTS The nystagmus optimal fixation function (NOFF) was defined as the logit transform of the fraction of data points meeting position and velocity criteria within a moving window. A decreasing exponential relationship was found between visual acuity deficit and the NOFF, yielding a 0.75 logMAR deficit for the poorest NOFF and diminishing deficits with improving foveation. As much as 96% of the points identified as foveation events fell within 0.25° of the actual target. Good correlation (r = 0.96) was found between NOFF and NAFX. Test-retest variability was 0.49 logit units. CONCLUSIONS The NOFF is a feasible method to quantify noisy nystagmus eye movement data. Its validation makes it a promising outcome measure for the progression and treatment of nystagmus during early childhood.

A Laser-Induced Mouse Model with Long-Term Intraocular Pressure Elevation

Purpose To develop and characterize a mouse model with intraocular pressure (IOP) elevation after laser photocoagulation on the trabecular meshwork (TM), which may serve as a model to investigate the potential of stem cell-based therapies for glaucoma. Methods IOP was measured in 281 adult C57BL/6 mice to determine normal IOP range. IOP elevation was induced unilaterally in 50 adult mice, by targeting the TM through the limbus with a 532-nm diode laser. IOP was measured up to 24 weeks post-treatment. The optic nerve damage was detected by electroretinography and assessed by semiautomatic counting of optic nerve axons. Effects of laser treatment on the TM were evaluated by histology, immunofluorescence staining, optical coherence tomography (OCT) and transmission electron microscopy (TEM). Results The average IOP of C57BL/6 mice was 14.5±2.6 mmHg (Mean ±SD). After laser treatment, IOP averaged above 20 mmHg throughout the follow-up period of 24 weeks. At 24 weeks, 57% of treated eyes had elevated IOP with the mean IOP of 22.5±2.5 mmHg (Mean ±SED). The difference of average axon count (59.0%) between laser treated and untreated eyes was statistically significant. Photopic negative response (PhNR) by electroretinography was significantly decreased. CD45+ inflammatory cells invaded the TM within 1 week. The expression of SPARC was increased in the TM from 1 to 12 weeks. Histology showed the anterior chamber angle open after laser treatment. OCT indicated that most of the eyes with laser treatment had no synechia in the anterior chamber angles. TEM demonstrated disorganized and compacted extracellular matrix in the TM. Conclusions An experimental murine ocular hypertension model with an open angle and optic nerve axon loss was produced with laser photocoagulation, which could be used to investigate stem cell-based therapies for restoration of the outflow pathway integrity for ocular hypertension or glaucoma.

Carcinoma-associated retinopathy in a young teenager with immature teratoma of the ovary

A 14-year-old African American girl presented with diminished vision in both eyes 1 week after undergoing an oophorectomy for a right ovarian mass. Systemic metastatic work-up was negative. Visual acuity was 20/40 in the right eye and 20/50 in the left eye. Slit-lamp biomicroscopy was unremarkable in both eyes. Fundus examination showed diffuse patchy areas of retinal pigment epithelial atrophy in the macula and peripheral retina bilaterally. Color vision had decreased in each eye. Electroretinography revealed nondetectable rod and cone responses. Both pattern and flash visual evoked potential (VEP) testing showed delayed latency in both eyes. She was treated with pulse intravenous methylprednisolone for 3 days along with intravenous immunoglobulins and rituximab, followed by systemic prednisolone and biweekly intravenous immunoglobulins and rituximab for 3 months. Antiretinal autoantibodies against 48-kDa (arrestin) and 64-kDa and 94-kDa proteins were positive, suggestive of carcinoma-associated retinopathy. After 3 months, visual acuity was 20/40 in each eye with improvement in color vision and VEP findings.

Improved visual function with dietary intervention in a child with lipemia retinalis

We present a 4.8-year-old female with grade 3 lipemia retinalis due to lipoprotein lipase deficiency, an abnormal electroretinogram, and bilateral decreased visual acuity. Strict dietary intervention resulted in reversal of lipemia retinalis, normalization of her electroretinogram, and improved visual acuity in both eyes.