The major problems are refractive errors like myopia and astigmatism.

问题是近视和散光等屈光不正。

Key features This refractive error has three key features: Image is formed behind the retina.

关键特征这种屈光不正有三特征：图像在视网后面形成。

This substance has a high refractive index, meaning the speed of light passing through it is greatly reduced.

这种物质折射率很高，意味着光穿过它速度会大幅降低。

This is also the reason why we use cycloplegic or muscle paralyzing drops before estimating the amount of refractive error.

这也是我们在测量屈光不正之前使用睫状肌麻痹或肌肉麻痹眼药水原因。

Glasses and contact lenses bend light to compensate for these refractive errors.

眼镜和隐形眼镜会弯曲光线以补偿这些屈光不正。

But many people develop refractive errors, either during childhood as their eyes are growing, or in later life as their eyes age.

但是很多人产生了屈光不正。或是发生在孩童时期当他们眼睛成长时，或是在后期当他们眼睛变老时候。

Keratomileusis corrects what are called refractive errors: imperfections in the way the eye focuses incoming light.

磨镶术可以纠正所谓屈光不正：眼睛聚焦入射光方式存在缺陷。

It's even possible to correct vision with surgery using lasers that change the shape of the cornea and alter its refractive properties.

甚至可以通过外科手术来矫正视力通过激光来改变形状和改变它折光特性。

People with refractive errors can still see color, movement, and light, but the details of what they're looking at are out of focus.

有屈光不正人仍然能够看到颜色，移动，和光，但是他们正在看细节是模糊不清。

Diagnosis Retinoscopy: a hand-held device that throws light in the eye and allowing us to observe its movements and reflection, hence helping to confirm the refractive error.

一种手持设备，向眼睛投射光线，观察眼睛运动和反射，从而帮助确认屈光不正。

The new glass he created was softer and easier to decorate, and had a higher refractive index, adding to its brilliance and beauty, and it proved invaluable to the optical industry.

他创造新玻璃更柔软， 更容易装饰，折射率更高，增添了它光彩和美丽，事实证明，它对光学工业来说是无价。

" In addition, refractive index can also be used to 'invisibility', for example, objects with high borosilicate glass materials can also be 'invisible' when moving in glycerol with a refractive index close to its own, " Chu noted.

“此外，折射率也可以用来‘隐形’，比如高硼硅玻璃材料物体在折射率接近自身甘油中运动时也可以‘隐形’，”褚指出。

This is actually one of the principles of realizing the " invisible cloak" , when the fabric of a garment and the air refractive index are the same, people can be freely " invisible" after wearing it, said the expert.

这位专家说，，这其实也是实现 “隐形斗篷”原理之一，当一件衣服面料与空气折射率相同时，人穿上后就可以自由 " 隐形" 。