Does blue-violet filtering in contact lenses improve contrast sensitivity?

PURPOSE: The work is aimed at (i) comparing photopic contrast sensitivity (CS) of healthy subjects in an indoor environment with either blue-violet filtering (BVF) or clear contact lenses (CLs) and (ii) investigating a possible dependence of the CS variation on the subjects' intrinsic CS, measured with clear CLs. METHODS: Optical transmittance of BVF and clear CLs was measured by a spectrophotometer. Photopic CS was measured monocularly on forty-one subjects (nineteen in the age range 20-36 years and twenty-two in the age range 44-66 years) by a digital optotype system at spatial frequencies from 1.5 to 18 cpd, wearing either clear or BVF CLs. The results are indicated as CSclear and CSBVF, respectively. RESULTS: Transmittance curves in the visible range of the two CLs are very similar, despite an absorption band in the BVF CL spectrum with the minimum of transmittance at 428 ± 4 nm equal to about 79%. For both CSclear and CSBVF, no significant CS difference was found between younger and older adults. The difference [log(CSBVF) - log(CSclear)] showed a decreasing trend and changed sign from positive to negative as a function of log(CSclear) with correlation Spearman's Rho coefficients ranging from 0.80 to 0.88 (p < 0.01 at all spatial frequencies). CONCLUSION: In the choice of a BVF CL, practitioners should take into consideration that it can influence photopic CS, improving it for subjects who have a relatively low CS with clear CLs, and worsening it for subjects who have a relatively high CS with clear CLs. BVF can affect positively the CS by reducing intraocular scattering. However, it can also cause a reduction in light intensity, which contributes to the formation of the retinal image. The positive or negative influence of BVF CLs compared to clear ones on CS is attributed to a balance among these effects.

Weak proactive cognitive/motor brain control accounts for poor children's behavioral performance in speeded discrimination tasks.

BACKGROUND: Motor and inhibitory control rely on frontal cortex activity, which is known to reach full maturation only in late adolescence. The development of inhibitory control has been studied using event-related potentials (ERP), focusing on reactive processing (i.e. the N2 and the P3 components). Scarce information exists concerning pre-stimulus activity as that represented by the Bereinshafstpotential (BP) and by the prefrontal negativity (pN). Further, no literature exists concerning the post-stimulus components originating within the anterior insula (pN1, pP1, pP2). This study aims at associating children performance with these motor-cognitive processing in frontal brain areas. METHODS: High-resolution EEG recordings were employed to measure ERPs from 18 children (12 years old) and 18 adults (28 years old) during a visuo-motor discriminative response task. Response time (RT), commission (CE) and omission errors, and RT variability were compared between groups. At brain level, two pre-stimulus (BP and pN) and seven post-stimulus (P1; pN1; N1; pP1; N2; pP2; P3) ERP components were compared between groups. RESULTS: Children showed slower and more variable RTs and poorer inhibition (higher CEs) than adults. At electrophysiological level, children presented smaller BP and pN. After stimulus onset, children showed lower amplitude of N1, pP1, P3, and pP2 components. The P1, pP1, N2 and P3 were delayed compared to adults. CONCLUSIONS: Our results demonstrate that children are characterized by less intense task-related proactive activities in frontal cortex, which may account for subsequent poor and delayed reactive processing and, thus, for inaccurate and slow performance.

Attitudes towards visual correction in sport: What coaches, physical education teachers and sports physicians think.

PURPOSE: To evaluate sport professionals' attitudes towards visual correction in sport. METHOD: A questionnaire was handed out in schools, gyms, sports centres and universities, to coaches, physical education teachers and final year students of motor science. The questionnaire was given to one group of sport physicians prior to a 1-day scientific update course on the benefits of contact lenses (CLs) in sport. At the end of the course, certain questions from the questionnaire were given out again in order to evaluate the effect of the update on their opinions. RESULTS: A total of 245 questionnaires were collected. The interviewees stated that correcting a vision defect during sports practice was important, but their propensity to suggest CLs for sport, though still rather high in value, showed a statistically significant drop. This drop did not occur if the CLs were recommended for competitive sports. This trend remained unchanged if a specific judgement was requested for the adolescent category. The tendency to suggest CLs was higher in CL wearers as compared to non-wearers. The sport with the lowest recommendation of CLs was swimming. In the sample of sports physicians, a specific education on the subject of CLs increased the propensity to adopt CLs in sports. CONCLUSIONS: The main "actors" in the sports sector regard correcting a vision defect during sport to be important. Nevertheless, their tendency to suggest CLs is significantly lower. Works that make these categories aware of the benefits of CLs in sport can certainly help to fill this gap.