Testing the visual field of children and adults with Rarebit: The role of task repetition on sensitivity.

Rarebit is a simple and user-friendly perimetry that tests the visual field by using tiny supra-threshold dot stimuli. It appears to be especially useful for examining the visual field of children who are under 12 years of age. However, previous data showed that the number of errors was higher in children than adults. We ask whether the different number of errors in these two groups depended on task learning and whether it may be accounted for by sensitivity differences or a response bias. Thirty-one children between 9 and 12 years of age and thirty-nine adults were tested three times with Rarebit perimetry. A bias-free sensitivity index, d', rather than the simple hit rate, revealed a group difference that remained after extensive task repetition. Indeed, d' increased with task learning in a similar way in the two groups so that group difference remained after practice. The response bias differed in the two groups, being conservative in the older group (criterion C >0) and liberal in the younger (criterion C < 0). Both biases disappeared with task learning in the third session, suggesting that response bias cannot account for the group difference in sensitivity after practice. When bias-free measures of sensitivity are used and task learning effects are minimized, Rarebit perimetry may be a more valuable method than simple mean hit rate (MHR) to enlighten sensitivity differences in the visual field assessment within the pediatric population.

Visual, motor, and psychomotor development in small-for-gestational-age preterm infants.

PURPOSE: To study causal links between the visual, cognitive, and psychomotor outcomes of premature babies who are small for gestational age (SGA). METHODS: A cohort study of 17 SGA cases and 34 controls who were appropriate for gestational age (AGA) was carried out. The cases were all premature babies without any other pathology. All subjects underwent a visual, mental, and psychomotor evaluation at 1 year of age. RESULTS: Of the SGA cases, 41% had a "below normal" visual acuity versus 17.7% of the AGA controls. At 1 year of age the SGA babies showed an odds ratio of 18.73 for low visual acuity, 9.09 for low mental performance, and no significant risk for a decreased psychomotor performance. CONCLUSIONS: In this small cohort of premature infants, the SGA babies were more prone to developing low visual performance and abnormal cognitive development.

The role of visual electrophysiology in mucopolysaccharidoses.

Visual electrophysiological techniques represent excellent means for assessing retinal, optic pathways and visual cortex function. Electroretinograms, visual evoked potentials, and clinical records of 17 patients with mucopolysaccharidosis registered in the neurophysiological database of our institution were reviewed retrospectively. Ten patients were on enzyme replacement therapy, 2 underwent bone marrow transplantation, one also keratoplasty. Changes in the electroretinogram pointed to the diagnosis of retinal dystrophy type rod-cone in 8 patients. In patients in whom severe corneal clouding precluded fundus oculi inspection and at an early stage before typical fundus appearance diagnosis was possible only using the electroretinogram. Visual evoked potentials were useful to confirm the loss of visual function in patients difficult to test clinically. The authors suggest the use of electroretinogram and visual evoked potentials primarily as research tools to describe the natural history and ophthalmologic outcome in mucopolysaccharidoses, although they may have clinical utility in very selected cases.

Illusory contours over pathological retinal scotomas.

Our visual percepts are not fully determined by physical stimulus inputs. Thus, in visual illusions such as the Kanizsa figure, inducers presented at the corners allow one to perceive the bounding contours of the figure in the absence of luminance-defined borders. We examined the discrimination of the curvature of these illusory contours that pass across retinal scotomas caused by macular degeneration. In contrast with previous studies with normal-sighted subjects that showed no perception of these illusory contours in the region of physiological scotomas at the optic nerve head, we demonstrated perfect discrimination of the curvature of the illusory contours over the pathological retinal scotoma. The illusion occurred despite the large scar around the macular lesion, strongly reducing discrimination of whether the inducer openings were acute or obtuse and suggesting that the coarse information in the inducers (low spatial frequency) sufficed. The result that subjective contours can pass through the pathological retinal scotoma suggests that the visual cortex, despite the loss of bottom-up input, can use low-spatial frequency information from the inducers to form a neural representation of new complex geometrical shapes inside the scotoma.

D-dimer evaluation of hemorrhagic orbital lymphangioma.

An 8-year-old boy with recurrent acute bleeding of lymphangioma of the left orbit is described. D-dimer levels increased as the size of the mass became stable, showing the effect of fibrinolysis within the hemorrhagic mass after clotting. D-dimer levels confirmed the possible use of conservative management of this lymphangioma.

Nonorganic (psychogenic) visual loss in children: a retrospective series.

BACKGROUND: Few studies provide follow-up information or systematic investigation of prognostic parameters of nonorganic (psychogenic) visual loss in children. METHODS: A retrospective case series analysis was performed on 58 patients younger than 16 years old who had nonorganic visual loss and underwent at least a 3-month follow-up clinic visit and/or telephone interview between 1992 and 2007 at a single institution in Italy. All patients underwent a full neurologic, ophthalmologic, and orthoptic evaluation. Visual electrophysiologic tests were performed in many patients as part of the evaluation. Neuroimaging was performed and psychiatric referral was made only as needed. We collected data on the age at onset, time to diagnosis of nonorganic visual loss, type and duration of visual symptoms, and concomitant psychologic or psychosocial difficulties. RESULTS: Visual deficits consisted mostly of reduced visual acuity (76%) and visual field defects (48%). The diagnosis of nonorganic visual loss could be reached with confidence by means of observing inconsistent performance on a wide array of visual function tests, and, in doubtful cases, by means of electrophysiologic investigations. The mean time from onset to diagnosis was 3.1 months. The mean duration of visual symptoms from reported onset to disappearance was 7.4 months. Complete resolution of all visual symptoms occurred in 93% of patients and did so within 12 months of diagnosis in 85% of patients. There was no correlation between the duration of visual symptoms and age at onset, sex, time to diagnosis, type of ocular symptoms, or presence of psychosocial or psychologic difficulties. CONCLUSIONS: Our study extends the follow-up information and confirms the findings of previous investigators in showing that nonorganic visual loss in children generally resolves spontaneously within 1 year and that no major psychiatric disorders are present or will appear after diagnosis. However, psychosocial stressors are often present and may predispose to this manifestation. There are no obvious predictors of rate of recovery.

Early predictors of severe course of uveitis in oligoarticular juvenile idiopathic arthritis.

OBJECTIVE: To determine whether demographic, clinical, and laboratory variables at onset of arthritis can predict the development and the severity of anterior uveitis (AU) in oligoarticular juvenile idiopathic arthritis (JIA). METHODS: In a retrospective study, a cohort of 366 patients with oligoarticular onset JIA from 3 pediatric rheumatology centers were evaluated. Patients were classified in 3 groups: severe uveitis (SU) with a mean >/= 2 uveitis relapses/year with complications or need for immunosuppressive therapy; mild uveitis (MU) with a mean