The major problems are refractive errors like myopia and astigmatism.

主要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.

关键特征种屈光不正有三个主要特征：图像在视网膜后面形成。

Now, when light enters glass, it's a different refractive index, so it actually bends the light.

现在，当光线进入玻璃时，因为它的折射率不同，所以它实际会弯曲光线。

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

种物质的折射率很高，意味着光穿过它的速度会大幅降低。

To combat this rain visibility problem, 3M actually developed these elements, which are retroreflectors that have different refractive indices.

为解决雨天能见度的问题，3M 公司实际件，它们是具有不同折射率的逆反射器。

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

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的原因。

And on this side, we have elements that have a 2.4 refractive index and work better in wet conditions.

而在另一侧，我们有折射率为 2.4 的素，它们在潮湿条件下表现更好。

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屈光不正。

Consider how refractive materials produce rainbows with varying colors.

试想折射材料如何通过不同颜色生成彩虹。

So on this side, we have elements that have a refractive index of 1.9, and they work well in dry conditions.

在一侧，我们有折射率为 1.9 的素，它们在干燥条件下表现良好。

Even when passing through natural materials with the highest refractive indexes, light can only bend so far.

即便光线穿过折射率最高的天然材料，其弯曲程度也有限。

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

但是很多人产生屈光不正。或是生在孩童时期当他们眼睛成长时，或是在后期当他们的眼睛变老的时候。

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

角膜磨镶术可以纠正所谓的屈光不正：眼睛聚焦入射光的方式存在缺陷。

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角膜的形状和改变它的折光特性。

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

有屈光不正的人仍然能够看到颜色，移动，和光，但是他们正在的看的细节是模糊不清的。

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，观察眼睛的运动和反射，从而帮助确认屈光不正。

So where the retroreflectors act ideally under dry conditions, as soon as water is on top of them, their refractive index is lowered by a ratio of 1.33.

因此，当反射器在干燥条件下理想工作时，一旦水覆盖在其，它们的折射率就会降低到 1.33 的比例。

Some have the regular glass beads on them, and other ones have the 3M elements on them with the 1.9 refractive index or the 2.4 refractive index or a combination of those.

有的面有普通的玻璃珠，有的面有折射率为 1.9 或 2.4 的 3M 件，或者是它们的组合。

" 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的物体在折射率接近自身的甘油中运动时也可以‘隐形’，”褚指出。

" A common misunderstanding is that a surgery can cure myopia, but in fact, the procedure can only remove the need for glasses, or apply the refractive function of glasses to the eyeball, " he said.

“目前最常见的误区是很多人都认为手术可以治愈近视，实际严格来讲，手术仅仅是‘摘镜’，也就是说，通过手术的手段，把眼镜的屈光度施加到眼球，让我们的眼球能够匹配过度生长的度数。