High mytopia, contacts, and detachment?

Question

i have high mytopia, i just went to my opt, he checked my eyes and the sheet says " OD- 675, OS-650 -050*20 " what does that mean? am i close to blind?

and he also dilated my eyes and looked all over with lights.

i see like 3 floaters in right eye.

should i be worried and go see a pro retina for detachment? my doctor said im fine but im just still worried.

is it safe for high mytopia to use contacts? anyone tried?

Answer 1

You've asked a number of questions.

When light passes through a window, a flat window, it passes pretty much straight through. It doesn't matter if the light is coming from an angle or perpendicular, it deviates a little, then keeps going the same direction out of the glass as it entered.

But in a convex lens, where the center is thick and the edges are then, as opposed to a concave lens where each side sort of looks like a little cave, and it's thin in the center and thick on the edges.

As light passes through the center, it keeps going straight as those surfaces are perpendicular to the light entering. But the further away from the lens center, the more angled the light hits the lens and the light rays change direction. The light rays way out to the edge are bent more than the ones in the center, but eventually all of the light rays focus at a point on the other side of the lens, the FOCAL POINT. The distance from the lens to that point is the FOCAL DISTANCE.

The power of the lens is equal to the formula P=1/d where d is in meters.

Light passing through the lens and focusing at a meter away would make that a +1.00 power lens. The units used are called DIOPTERS.

If the lens focuses at a half meter, +2.00

third of a meter, +3.00

quarter of a meter, +4.00

fifth of a meter (20 cm) +5.00

You are already focused at 1/6 of a meter in front of you or a little bit more (closer). So you are +6.00 too powerful (OK +6.50 diopters too powerful). So beyond a sixth of a meter away, and things get blurred.

So you need a -6.50 lens to neutralize that power. And that power moves that focal point from a little closer than a sixth of a meter in front of you out to infinity... or far away so you can see the clock or board at school or that cute lady over there.

As long as when you are wearing your Rx you can see clearly, and you measure to 20/20 or 1.0 depending on the units you use in your country, you have GOOD EYES!

In people who are relatively high myopes or nearsighted or short sighted, there is a statistical increase in the chance that you will get a retinal tear. If you get a tear, you'll probably see a sudden increase in the floaters. The symptoms used are lots of dots, dozens of dots, hundreds of dots, spider webs, cobwebs, angle hair, blobs, haze, fog, clouds, smog, etc.

The outer layer of the eye is the white layer, it's called the sclera. When it gets to the front, it changes it's architecture and the little fibers become parallel. It also changes to a different curve, a shorter radius curve. This clear part is called the Cornea.  When you look at someones eyes and you see they have brown or blue or green or gray or hazel or ? eyes, you look through their cornea at the IRIS. IT has a hole in it, PUPIL, and on the other side of that hole is the LENS.

The iris, or colored part passes around the eye next to the white layer, and it is full of blood vessels. This layer in the back is called the  CHOROID.  The IRIS and Choroid together (along with the ciliary body which has muscles in it at the edge of the iris which bend and pull on the lens to allow it to change focus when we want to see up close) are called the UVEAL TRACT. If one took the white part away, and looked at the choroid and iris, it would look like a grape, hence uveal tract. (Spanish for grape is uva)

The third layer next to the choroid in the back is the retina. And in the center of the eye is the Vitreous Humor or GEL.

This gel is produced up near the front of the retina and is composed of collagen fibers with a surrounding coat of muccopolysaccharides. The outer mucous stuff surround the collagen fibers has molecules that face each other and have the same charges. This causes the fibers to repulse or stay a certain distance away from each other. this distance is exactly the wavelength of light, so the gel or vitreous is transparent.

The vitreous lays against the retina in the back, but is only lightly attached to the surface over the nerve or macula or some blood vessels. As we age, the vitreous breaks down and becomes watery (syneresis). There are a whole series of cavities in the vitreous, but more or less it's a blob of gel.

As it gets watery with age, it starts to slosh around more and more. Any cells in it we may see as floaters. There's a canal in the center of the vitreous which goes from the nerve all the way to the back of the lens up front. This used to have blood vessels in it when the lens is forming and the eye is forming as an embryo. Sometimes remnants of that vessel system persist, and we seem them as floaters. But there are other cells, hyalocytes too.

Now that the vitreous is sloshing around, it can tug on the retina up front where it is tightly attached. If it tugs on the retina we can see that as a light flash (PHOTOPSIA).  But if the gel tugs hard enough it can tear the retina. If it does so, one may see lots of floaters which are described above. If the red cells float freely, we see dots. If they line up along the collagen fibers, we see patterns such as cobwebs, or spider webs, or angel hair, etc.

If the liquid vitreous gets beneath the retina through the tear, the retina will float off. That's a retinal detachment. The chances of a myope getting an RD are about 6 times more than the normal population, but still it's a low percentage. About 1 in 200 of us get a tear per year. In those which higher myopia, it's about 3%, or 6 times more. Still 97% DON'T.

Contacts sit on the corneal surface. They have NOTHING to do with your vitreous or retina. They have their own set of problems. Take a look at the number of questions in this forum that deal with contact lenses. (hint).

Answer 2

A retinal detachment has the following symptoms. Lots and lots of floaters, kind of like a shower, a black curtain in the sides, bottoms or tops of the eyes, loss of sight.

You might be having a vitreous separation or detachment, which is something completely different. Or you might just have debris in your eye.

The retina is a funny business. Most people who I know who have had a retinal detachment would not put their faith in a normal optician as it is a specialist field, and opticians can miss problems with the retina.

Answer 3

-6.75 and -6.50 are just the powers of the lenses that will help focus light into your eyes for you to see clearly.  The -0.50 is a small correction for astigmatism and the x020 is a designation for the direction that the astigmatism correction is ground into the lens.  You are not close to blind and will not become blind just by having a high prescription.

If you had a retinal detachment, the optometrist would have seen it and referred you to an ophthalmologist or retina specialist right away, as it is an emergency situation.  You do not need to see a retina specialist just for being a high myope.  An optometrist is qualified and able to detect retinal tears and retinal detachments; he or she is just not qualified to operate on them.

The doctor will want to dilate you at least once a year, though, because being a high myope puts you at greater risk for a retinal detachment.  The eyes of myopes are longer than average which stretches out the retina.  This is what increases the risk for a detachment.

Your floaters are normal.  They are just little pieces of the back of your eye that have broken loose and are floating through the liquid inside your eye.  This sounds bad but is usually harmless.  

If you notice A LOT of floaters at once (like a curtain or shower), that can be a sign of a retinal detachment.  Other signs are flashes of light or vision loss.

And yes, it is safe for high myopes to wear contacts.