The Role of Crystallins in Maintaining Lens Transparency

Crystallins are adapted not to crystallise; the eye lens needs to be a highly concentrated solution, but it needs to avoid small crystals or aggregates, since they would scatter light and make the lens opaque. Our lenses achieve this by mixing together several different crystallins, which together form a uniform, glassy solution. The protein molecules are arranged in a way which means that their refractive index is nearly the same as glass- which makes the lens transparent. This is due to the small size of the protein molecules, less than 10 nm in diameter, and their close packing at high concentration

The lens contains three major types of crystallins, making up about 90% of the protein. Alpha crystallins are the most common. They are composed of two similar types of protein chain, which associate to form large spherical complexes containing about 40 chains. These large spheres repel one another and distribute themselves throughout the lens cells. Beta crystallins, shown here from, also form oligomeric complexes (contains a limited number of monomers), typically formed of two or six copies of the chain. There are several similar beta crystallins, which can mix and match to form a bunch of different types of oligomers. Finally, gamma crystallins are monomeric, and serve as a weak glue to gently bind the alpha crystallins together.

Our crystallin proteins need to last our entire life, so the lens contains a powerful method to protect them. Alpha crystallin acts as chaperone, finding damaged proteins and binding to them before they can form translucent or opaque complexes. Unfortunately, in spite of this protection, the damage builds up as we age, as crystallins are broken or unfolded or oxidized. Slowly, the damage leads to progressive build-up of opaque aggregates, leading to cataracts. 

The NHS

The NHS was launched in 1948. It was born out of a long-held concept that healthcare should be available to all, regardless of wealth – one of the NHS's core principles. With the exception of some charges, such as prescriptions, optical services and dental services, the NHS in England remains free at the point of use for all UK residents. This currently stands at more than 64.6 million people in the UK.

The NHS in England deals with over 1 million patients every 36 hours. It employs more than 1.5 million people, putting it in the top five of the world’s largest workforces, alongside the US Department of Defence, McDonalds, Walmart and the Chinese People’s Liberation Army.

The NHS in England is the biggest part of the system by far, catering to a population of 54.3 million and employing around 1.2 million people. Of those, the clinically qualified staff include 150,273 doctors, 40,584 GPs, 314,966 nurses and health visitors, 18,862 ambulance staff, and 111,127 hospital and community health service (HCHS) medical and dental staff. The NHS in Scotland, Wales and Northern Ireland employs 161,415; 84,000 and 66,000 people respectively.

Funding for the NHS comes directly from taxation. Since the NHS transformation in 2013, the NHS payment system has become underpinned by legislation. The Health & Social Care Act 2012 moves responsibility for pricing from the Department of Health, to a shared responsibility for NHS England and NHS Improvement. The purpose of the 2012 act was to devolve decision-making from a centralised NHS to local communities, with the intent of making it more tailored to specific needs. The act aimed to put patients at the centre of the NHS, change the emphasis of measurement to clinical outcomes, and empower healthcare professionals, in particular GPs.


When the NHS was launched in 1948, it had a budget of £437 million (roughly £15 billion today).For 2015/16, the overall NHS budget was around £116.4 billion, with NHS England  managing £101.3 billion of this.