With the rule astigmatism against the rule astigmatism.

用散光規則反對散光規則。

What is the rule here?

這裡的規則是什麼？

The rule is in cornea vertical meridian is steeper or has more converging power than horizontal meridian.

規則是角膜的垂直經線比水準經線更陡峭或更有匯聚力。

So if any patient has steeper vertical meridian than horizontal meridian, he or she has with the rule astigmatism.

是以，如果任何患者的垂直子午線比水準子午線陡峭，他或她就會出現散光。

And if any patient has steeper horizontal meridian than vertical meridian, then it's called against the rule astigmatism.

如果任何患者的水準子午線比垂直子午線陡峭，那麼這就是所謂的散光。

Now you might be thinking why does vertical meridian is steeper than horizontal meridian in human eyes.

現在你可能在想，為什麼人眼的垂直經線比水準經線陡峭？

There are two main reasons.

主要原因有兩個。

One, vertical corneal diameter is shorter than horizontal corneal diameter.

其一，垂直角膜直徑比水準角膜直徑短。

And two, eyelid pressure on cornea.

第二，眼瞼對角膜的壓力。

Vertical meridian is normally 0.25 diameter steeper than the horizontal meridian due to pressure of eyelids.

由於眼瞼的壓力，垂直經線通常比水準經線陡 0.25 直徑。

Let's understand with the rule and against the rule astigmatism with example.

讓我們以散光為例，瞭解散光的規則和反規則。

With the rule astigmatism, minus 2, minus 1, 170 degree axis.

根據散光規則，減 2，減 1，170 度軸。

Against the rule astigmatism, minus 3, minus 2, 100 degree axis.

逆規則散光，負 3，負 2，100 度軸。

Let's see how minus 2, minus 1, 170 degree axis is with the rule astigmatism.

讓我們看看負 2、負 1、170 度軸是如何與散光規則結合的。

Now let's distribute this power into the optical cross.

現在，讓我們把這些能量分配到光學十字架上。

This is optical cross, 170 degree will be somewhere here and 80 degree will be somewhere here.

這是光學交叉，170 度在這裡，80 度在這裡。

Now here minus 2 is spherical power.

現在這裡的減 2 是球形功率。

So it will be in both meridian, here in 170 degree also and in 80 degree also.

是以，它將出現在兩個子午線上，這裡是 170 度，這裡也是 80 度。

And minus 1 cylinder is 170 degree axis.

減去 1 個氣缸就是 170 度軸。

So the power will be 90 degree apart or here in 80 degree.

是以，功率將相差 90 度，這裡是 80 度。

In 80 degree meridian, we have total minus 2, minus 1 or minus 3 diameter.

在 80 度經線上，我們有負 2、負 1 或負 3 的總直徑。

And in 170 degree meridian, we have minus 2 diameter.

而在 170 度經線上，我們有負 2 的直徑。

So to make the eye emetropic or zero power, we need to subtract 3 diameter from vertical meridian and 2 diameter from horizontal meridian.

是以，要使眼睛的視力為零，我們需要從垂直子午線上減去 3 個直徑，從水準子午線上減去 2 個直徑。

That means vertical meridian has more converging power or steeper than the horizontal meridian.

這意味著垂直子午線比水準子午線具有更強的匯聚能力或更陡峭。

As we already know that if vertical meridian has more converging power than horizontal meridian, then it's called with the rule astigmatism.

我們已經知道，如果垂直子午線的會聚力大於水準子午線，則稱為散光。

So minus 2, minus 1 at 170 degree axis is a with the rule astigmatism.

是以，170 度軸上的負 2、負 1 就是散光。

Now, vertical meridian doesn't mean only 90 degree and horizontal meridian doesn't mean only 180 degree.

現在，垂直子午線並不意味著只有 90 度，水準子午線也不意味著只有 180 度。

Meridian in between 70 degree to 110 degree that is 90 degree plus minus 20 is considered vertical meridian.

介於 70 度到 110 度之間的子午線，即 90 度加減 20 度被視為垂直子午線。

And meridian in between 160 to 20 degree that is 180 degree plus minus 20 is considered horizontal meridian.

而在 160 度到 20 度之間的子午線，即 180 度加減去 20 度，被視為水準子午線。

Now, tips to identify with the rule and against the rule astigmatism.

現在，提示您識別符合規則和違反規則的散光。

We know that power in ophthalmic lenses are present in 90 degree apart from the cylinder axis.

我們知道，眼科透鏡中的功率與鏡筒軸線呈 90 度角。

So minor cylinder power with axis between 160 to 20 degree that is 180 degree plus minus 20 will be with the rule astigmatism.

是以，軸線在 160 至 20 度（即 180 度加減 20 度）之間的小圓柱度數將符合散光規則。

Because minor cylinder in 180 degree means we are subtracting power from 90 degree meridian.

因為 180 度的小圓柱體意味著我們要從 90 度的子午線上減去功率。

So minus power in 160, 165, 170, 175, 180, 5, 10, 15 or 20 degree will be example of with the rule astigmatism.

是以，負功率在 160、165、170、175、180、5、10、15 或 20 度時就會出現散光。

Minor cylinder power with axis in between 70 to 110 degree that is 90 degree plus minus 20 will be against the rule astigmatism.

軸線在 70 至 110 度（即 90 度加減 20 度）之間的小圓柱度數為散光。

Because minor cylinder axis in 90 degree means we are subtracting power from 180 degree meridian that is against the rule astigmatism.

因為小圓柱軸在 90 度，意味著我們要從 180 度的子午線上減去功率，這違反了散光的規則。

So minor cylinder in 70 degree, 75 degree, 80 degree, 85 degree, 90 degree, 95 degree, 100 degree, 105 degree, 110 degree will be example of against the rule astigmatism.

是以，70 度、75 度、80 度、85 度、90 度、95 度、100 度、105 度、110 度的小圓柱都是散光的例子。

If still you have confusion regarding optical cross power and prescription power then you can watch my video about optical cross.

如果您對光學交叉功率和處方功率仍有困惑，可以觀看我製作的有關光學交叉的視頻。

Link is available in the description.

說明中提供了鏈接。

Now summary of this video.

現在總結一下這段視頻。

The rule is vertical meridian is steeper than horizontal meridian.

規則是垂直子午線比水準子午線陡峭。

Vertical meridian is steeper because of shorter vertical corneal diameter and eyelid pressure.

垂直經線更陡峭，因為角膜垂直直徑更短，眼瞼壓力更大。

Vertical meridian is generally 0.25 diameter steeper than the horizontal meridian.

垂直子午線一般比水準子午線陡 0.25 直徑。

Meridian in between 70 to 100 degree is considered vertical meridian.

70 至 100 度之間的子午線被視為垂直子午線。

Meridian in between 160 to 20 degree is considered horizontal meridian.

160 至 20 度之間的子午線被視為水準子午線。

Minor cylinder power with axis in between 160 to 20 degree will be the with the rule astigmatism and minor cylinder power with axis in between 70 degree to 110 degree will be against the rule astigmatism.

軸線在 160 度到 20 度之間的小圓柱度數為順向散光，軸線在 70 度到 110 度之間的小圓柱度數為逆向散光。

Stay with smart optometry and study optometry smartly.

堅持智能驗光，智能學習驗光。