The major problems are refractive errors like myopia and astigmatism.

主要问题是近视和散等屈不正。

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

关键特征这种屈不正有三个主要特征：图像在视网膜后面形成。

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

这种物质的折射率很高，意味着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.

为了解决雨天能见度的问题，3M 公司实际上开发了这些元件，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.

这也是我们在量屈不正之前使用睫状肌麻痹或肌肉麻痹眼药水的原。

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 的元素，它们在潮湿条件下表现更好。

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

现在，当线进入玻，为它的折射率不同，所以它实际上会弯曲线。

Consider how refractive materials produce rainbows with varying colors.

试想折射材料如何通不同颜色生成彩虹。

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

眼镜和隐形眼镜会弯曲线以补偿这些屈不正。

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不正。或是发生在孩童期当他们眼睛成长，或是在后期当他们的眼睛变老的候。

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

在这一侧，我们有折射率为 1.9 的元素，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.

即便线折射率最高的天然材料，其弯曲程度也有限。

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不正：眼睛聚焦入射的方式存在缺陷。

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

甚至可以通手术来矫正视力，利用激改变角膜的形状并调整其屈特性。

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

患有屈不正的人仍能看见颜色、运动和线，但他们所看物体的细节却模糊不清。

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，向眼睛投射线，观察眼睛的运动和反射，从而帮助确认屈不正。

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.

此，当反射器在干燥条件下理想工作，一旦水覆盖在其上，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.

有的上面有普通的玻珠，有的上面有折射率为 1.9 或 2.4 的 3M 元件，或者是它们的组合。

" 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，实际上严格来讲，手术仅仅是‘摘镜’，也就是说，通手术的手段，把眼镜的屈度施加到眼球上，让我们的眼球能够匹配度生长的度数。

" 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’，比如高硼硅玻材料的物体在折射率接近自身的甘油中运动也可以‘隐形’，”褚指出。