Visual function in Noonan and LEOPARD syndrome.

The aim of the study was to assess various aspects of visual and visuoperceptual function in patients with Noonan syndrome (NS) or LEOPARD syndrome (LS) with mutations affecting the PTPN11, SOS1 and RAF1 genes. Twenty-four patients were assessed with a battery of tests assessing visual function including ophthalmological and orthoptic evaluation and age appropriate behavioural visual tests, including measures of crowding acuity (Cambridge crowding cards), and stereopsis (TNO test). Twenty-one subjects were also assessed with the visuo-motor integration (VMI) test. Twenty of the 24 patients (83%) had abnormalities of visual function on at least one of the tests used to assess visual function or on ophthalmological examination, and 7 of 21 (33%) also had abnormalities on VMI. Ocular movements and stereopsis were most frequently abnormal (50% and 79%, respectively). Our results suggest that visual and visuoperceptual abilities are commonly impaired in patients with Noonan and LEOPARD syndrome and they are probably related to a multifactorial etiology.

LRRK2-associated Parkinson's disease patients have better stereopsis than idiopathic Parkinson disease.

OBJECTIVES: Visual dysfunctions are frequent and have several manifestations in idiopathic Parkinson's disease (PD). However, the characteristics of these complications in LRRK2 (leucine-rich kinase 2)-associated PD patients still lack systematic research. The purpose of this study is to assess visual functions of LRRK2-associated PD patients. PATIENTS AND METHODS: Twenty-five (25) PD patients with LRRK2 R1628P and G2385R variants were included in the study and compared to 28 PD patients without these variants and 28 age-matched healthy controls. The genotypes of PD patients were kept double-blinded. Information on age, sex, disease duration, the movement disorder society-unified Parkinson's disease rating scale (MDS-UPDRS), Hoehn and Yahr staging scale (H&Y), Mini-Mental Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were included. Visual functions assessment included color perception, contrast sensitivity and stereopsis. RESULTS: PD patients with or without LRRK2 R1628P and G2385R variants have declined contrast sensitivity, diminished color discrimination and damaged stereopsis. There was no significant difference in retinal level visual deficiency (color discrimination and contrast sensitivity) between PD with LRRK2 variants and those without, but cortex level visual function, i.e. stereopsis is better in PD with LRRK2 variants than non-carrier PD patients. The associated factors of stereopsis are different. The stereopsis is associated with MoCA scores independently in non-carrier PD patients, but with UPDRSIII scores in LRRK2-associated PD patients. CONCLUSIONS: Visual functions are similarly affected in PD patients with and without LRRK2 R1628P and G2385R variants, but LRRK2-associated PD patients have better stereopsis than idiopathic PD patients.

Visión binocular en pacientes operados de esotropía congénita con cuatro años de evolución / Binocular vision in patients operated of congenital esotropia with four years of follow-up

Objetivo: describir los resultados quirúrgicos y la obtención de fusión y estereopsia en operados de esotropía congénita, después de cuatro años de seguimiento y su relación con el ángulo de desviación preoperatorio y la edad al momento de la primera cirugía. Métodos: estudio descriptivo, longitudinal y prospectivo de una serie de casos, operados de esotropía congénita desde el año 2007 al 2010, seguidos durante cuatro años por consulta en el Instituto Cubano de Oftalmología Ramón Pando Ferrer. Se analizaron las variables edad al diagnóstico, ángulo de desviación preoperatorio y posoperatorio, edad al momento de la primera cirugía, presencia de fusión, estereopsia y desarrollo de ambliopía. Resultados: el ángulo de desviación preoperatorio promedio de los pacientes estudiados fue de 39,8 dioptrías y la media de la edad al momento de la primera cirugía fue 22,5 meses (DE 9,2). La media de supervivencia del alineamiento ocular fue de 39,3 meses, y fue superior en los pacientes con un ángulo de desviación preoperatorio menor de 40 dioptrías y con menos de 24 meses de edad al momento de la primera cirugía (p= 0,001). Presentaban fusión y estereopsia a los 4 años el 57,7 y el 26,9 por ciento de los pacientes. La media del número de cirugía fue de 1,42 (DE ± 0,504) a los 4 años. La causa más frecuente de segunda cirugía fue la hiperfunción del oblicuo inferior (19,2 por ciento). Conclusiones: la presencia de fusión y de estereopsia a los 4 años de evolución es mayor en aquellos pacientes con menor ángulo de desviación preoperatoria y con menos de 2 años de edad a la primera cirugía(AU)

Neural correlates of chromostereopsis: an evoked potential study.

Chromostereopsis is an illusion of depth arising from colour contrast: ocular chromatic aberrations usually make red appear closer to the viewer than blue. Whereas this phenomenon is widely documented from the optical and psychophysical point of view, its neural correlates have not been investigated. To determine the cortical processing of this colour-based depth effect, visual evoked potentials (VEPs) to contrasts of colour were recorded in 25 subjects. Chromostereopsis was found with the stimuli combining spectra extremes. VEP amplitude but not latency effects were observed to colour depth cues, suggesting an underlying, depth-specific slow negative wave, located using source modelling first in occipito-parietal, parietal, then temporal areas. The component was larger over the right hemisphere consistent with RH dominance in depth processing, likely due to context-dependent top-down modulation. These results demonstrate that the depth illusion obtained from contrast of colour implicates similar cortical areas as classic binocular depth perception.

Sex differences in spatial ability in children.

There is considerable evidence that sex differences in spatial ability exist in adults, with males outperforming females at every age after puberty. It is difficult, however, to find sex differences in children younger than 13. This is due in part to the lack of adequate measures of spatial ability for use with children. We report the use of spatial tests for children that are similar to those that have shown large sex differences in adults and may be measuring ability comparable to adult spatial ability. Four tests of mental rotation and spatial visualization were given to two samples of children. The first sample consisted of 81 children (39 males and 42 females) aged 9 to 12 years. The second sample consisted of 42 children (21 males and 21 females) aged 9 to 13 years. Sex differences of .4-.6 standard deviations were found on three tests in both samples. These results indicate that sex differences in spatial ability can be found in preadolescents if appropriate tests are used. Measurement of these abilities in children facilitates the investigation of possible biological and sociocultural contributors to the sex differences in spatial ability.

Binocular interactions and spatial disparity sensitivity in the superior colliculus of the Siamese cat.

In Siamese cats, a genetically determined massive misrouting of retinal ganglion cells toward the contralateral hemisphere, as well as an accompanying strabismus, is believed to underlie the extreme paucity of binocular cells in the primary visual cortex. However, binocular cells have been shown to be present in more important numbers at the collicular level. The present study aims at investigating binocular interactions and sensitivity to spatial disparity in the superior colliculus of the Siamese cat. The activity of single units was recorded in the superficial layers of paralyzed and anesthetized Siamese cats. Although most collicular cells were monocularly driven, a significant proportion could be driven through both eyes (34/216 or 16%). Upon isolation of a binocular cell, the receptive fields were separated, then simultaneously stimulated with two light bars. A temporal delay was introduced between the arrival of the bars in the receptive fields to generate spatial disparities (-3 degrees to +3 degrees, in 0.5 degrees or 1 degree steps). Results showed that some binocular cells presented disparity tuning profiles similar to the tuned excitatory (12/34), tuned inhibitory (2/34), near (2/34) and far (3/34) cells found at various cortical levels in the normal cat. These interactions might allow for coarse binocular fusion as well as play a role in the initiation of vergence and the fixation of the eyes upon the appropriate plane of vision.