Did primates develop three-colour vision because they began to live in the day or did they begin to live in the day due to the appearance of this trait? A small animal with bulging eyes – the tarsier – may hold the answer to this question.

 

American scientists analyzed the genes that encode photopigments in the eye of the tarsier, a small primate that branched off early on from monkeys, apes, and humans. They showed that the last common ancestor of living tarsiers had three-colour vision similar to that of monkeys and apes. However, they had enlarged eyes, suggesting they were active at night.

 

According to the researchers, this shows that tarsiers first adapted to dim light levels, such as twilight or the full moon. These light conditions were dark enough to favour large eyes but still bright enough to support trichromatic colour vision. This compromise would have helped the primates switch to daytime living, which allowed them to better see their prey, their predators, and other primates and to expand their territory.

 

Source: http://www.sciencedaily.com/releases/2013/03/130327132537.htm

 

A British study shows that compared to the modern human brain, the brain structure of Neanderthals focussed much larger areas on vision and movement. This difference could have contributed to their extinction.

 

Neanderthals’ brains were similar in size to those of modern humans, but their eyes were larger. Having larger brain areas related to vision and movement meant that there was less room left over to deal with the social interactions required for life in large groups.

 

“Smaller social groups might have made Neanderthals less able to cope with the difficulties of their harsh Eurasian environments because they would have had fewer friends to help them out in times of need,” explains lead author Eiluned Pearce from the University of Oxford. “Overall, differences in brain organisation and social cognition may go a long way towards explaining why Neanderthals went extinct whereas modern humans survived.”

 

The same researchers had previously shown that humans living in higher latitudes had more areas of the brain dedicated to vision in order to cope with low light levels. They offer the hypothesis that Neanderthals would have developed larger eyes because they evolved in Europe, while their contemporary humans originated from Africa.

 

Source:  http://www.sciencedaily.com/releases/2013/03/130319093639.htm

 

In Great Britain, the national press has sounded the alarm about eye infections related to contact lens wear. In response, the British Contact Lens Association (BCLA) is pushing for mandatory warnings to wearers about the danger of contact with water.

 

A number of articles have reported incidents of infection from Acanthamoeba keratitis, some of which resulted in the loss of an eye. “A significant risk factor for this condition is contact with water, either from inadequate drying of the hands after washing, showering, swimming, or using a hot tub while wearing lenses, cleaning the lens case with water or even rinsing the lenses with water,” reminds BCLA president Dr. Catharine Chisholm.

 

The BCLA would like to have a “no water” warning on contact lens packaging, and is producing “no water” stickers for members to put on lens boxes at collection and a patient information leaflet.

 

However, according to the Association of Contact Lens Manufacturers (ACLM), other factors are at work, such as inadequate market legislation and obsolete sales laws. For the ACLM, water is only one of many factors to be considered.

Source:

http://www.opticianonline.net/Articles/2013/03/08/30811/BCLA+argues+merits+of+’no+water’+warnings.htm

 

Hard contact lenses used in orthokeratology, a non-invasive technique to reduce nearsightedness and astigmatism, have long proved to be effective. A new study explains why they are successful.

 

Patients receiving orthokeratology treatment wear hard contact lenses overnight and wake to clearer vision. The study by Korean researchers, published in the March issue of Optometry and Vision Science, shows that the lens works because it flattens the front surface of the cornea. Scientists had been wondering whether the lens reshapes just the front surface of the cornea or the entire cornea.

 

The Korean researchers conducted their research on 18 young adults with relatively mild myopia who wore the lenses for 14 consecutive nights. After the first night, the front surface of the cornea had been significantly reshaped, and vision showed a marked improvement. After 14 nights, the participants had near-normal uncorrected vision. Approximately 80% of the improvement occurred over the first 4 nights.

Source:

http://www.sciencedaily.com/releases/2013/03/130304123124.htm

 

A team of Canadian and international researchers has found a new type of retinoblastoma, an eye cancer that affects babies.

 

The researchers showed that a single cancer gene (an oncogene) drives an aggressive retinoblastoma that starts long before birth in families with no history of the disease. These tumours are much larger than those found in babies of the same age who have hereditary retinoblastoma. About 2% of patients are affected by this form of the disease.

 

“We’ve thought for a long time that all retinoblastoma were caused by loss of the retinoblastoma gene,” explains Dr. Brenda Gallie, head researcher and an ophthalmologist affiliated with the Hospital for Sick Children (SickKids) and the University of Toronto. “Our study now reveals that’s not the whole story: a new type of retinoblastoma, with normal retinoblastoma genes, is instead driven by extra copies of a powerful cancer gene, causing the cancer to grow very rapidly long before birth. The average age of diagnosis is four months.”

 

The diagnosis is generally made after parents notice their child has a white rather than black pupil.

Source:

http://www.sciencedaily.com/releases/2013/03/130312231012.htm