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Thursday, January 1, 2015

Have Scientists found a cure for correcting 'blindness' ?

அரிது அரிது, மானிடராய் பிறத்தல் அரிது; மானிடராய் பிறந்த காலையின் கூன் குருடு செவிடு நீங்கி பிறத்தல் அரிது ~ the immortal words of Tamil Poetess Avvaiyar.  It means it is difficult (rare) to be born as a human being; having been born – it is rare to be a birth devoid of physical challenges like dumb, deaf, blind …. the significance is that one should use appropriately such good birth and do good to the Society.

The life of blind is very tough. Blindness is a lack of vision.  Various scales have been developed to describe the extent of vision loss and define blindness. Total blindness is the complete lack of form and visual light perception and is clinically recorded as NLP, an abbreviation for "no light perception."  Blindness is defined by the World Health Organization as vision in a person's best eye of less than 20/500 or a visual field of less than 10 degrees.

AnthahakKavi – a reference to a well known poet who lived in 17th century – Veeraraghava Mudaliyar, known so due to his vision impairment.  He was blind from birth, yet established a mark in Tamil literary World distinguishing himself with his poetic talents and erudition.  John Milton (1608 – 1674) a Civil servant in England is better known as the great poet. He wrote at a time of religious flux and political upheaval, and is best known for his epic poem Paradise Lost (1667).  By 1654, Milton had become totally blind; the cause of his blindness is debated but bilateral retinal detachment or glaucoma are most likely. His blindness forced him to dictate his verse and prose to amanuenses (helpers), one of whom was the poet Andrew Marvell. Milton's magnum opus, Paradise Lost, was composed by the blind and impoverished Milton and by some accounts, the  poem reflects his personal despair at the failure of the Revolution, yet affirms an ultimate optimism in human potential.  In 1671, Milton published ‘Paradise regained’ – emphasising the idea of reversals.  As implied by its title, Milton sets out to reverse the "loss" of Paradise. Thus, antonyms are often found next to each other, reinforcing the idea that everything that was lost in the first epic will be regained by the end of this "brief epic."

The troubles of  ‘visually challenged people’ are too well known – and there are very many ways by which we can be of some help, mitigating their trouble.  The eternal challenge for Science is a cure for blindness.  MailOnline queries on whether Scientists have found a cure and whether radical gene therapy that restores sight in mice and dogs could be used on humans.   The post reveals that a  radical form of gene therapy that remodels eye cells into light receptors has allowed scientists to partially restore the sight of animals with inherited blindness. Scientists say the same technique could one day be used to treat people with retinitis pigmentosa - an inherited condition resulting in progressive loss of sight. In early tests on blind rescue dogs with a similar condition, showed they could restore sufficient light sensitivity for the animals to distinguish between flashing and non-flashing lights. In normal mice with working photoreceptors, stimulating the retina produced a variety of responses in retinal ganglion cells, the output of the eye.  Photoswitches inserted into retinal ganglion cells (RGC) of blind mice produce much less variety of response (all evenly red means the cells fire at the same time), while blind mice with photoswitches inserted into bipolar cells (ON-BC driven) exhibit much more variety in their retinal response to light, closer to that of normal mice. 

Blind mice given the same treatment became as good at navigating a water maze as normal mice. Two components of the 'hybrid' treatment involve a gene that alters non-light sensitive cells and an injected chemical 'photoswitch'. 'The dog has a retina very similar to ours, much more so than mice, so when you want to bring a visual therapy to the clinic, you want to first show that it works in a large animal model of the disease,' said Professor Ehud Isacoff, lead research from the University of California, Berkeley. The therapy is one of a number of potential treatments for blindness at early stages of development, two of which yielded exciting trial results this year. In October scientists from the Massachusetts –based company Ocata Therapeutics, formerly known as Advanced Cell Technology, showed that stem cell-derived retinal cells could safely be implanted into patients and improve vision in some cases. Earlier this year scientists at Oxford University hailed trial results from a genetic therapy for choroideremia, a rare inherited cause of blindness that affects one in 50,000 people.

The new treatment uses a virus to insert a gene into normally these cells in the retina that gives them the potential to 'see'. The gene makes a protein that acts like a lock. When the right molecular key from the photoreceptor switch is slotted into the lock, light sensitivity is turned on. The therapy is said to show promise because although diseases such as RP destroy the eye's photosensitive cells, other cells in the retina are often left intact and unharmed.

Scientists say the technique could one day be used to treat people with retinitis pigmentosa - an inherited condition resulting in progressive loss of sight ~ that provides great hope to humanity.

With regards – S. Sampathkumar
17th Dec 2014.


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