But Wait! There’s More!

Last week we had talked about floaters and how most of the time (85%) of the time it was a normal aging change that happens to most people. We also discussed the possibilities, signs and symptoms of a retinal detachment. There are, however, other things that can give the appearance of spots in your vision. Sadly, some of these can sometimes be ominous.

The eye can be broken down into 3 functional components. The eye (the part that receives the image and translates it into an electrical signal), the optic nerve (transports the electrical signal from the eye to the brain), and the brain (processes the signal to tell you what you are seeing). As we talked about last week, debris in the vitreous casts a shadow on the retina. The retina detects the shadow, sends the information to the brain and the brain sees the spots. This is an example of how the first function in the system can cause spots. Another less common problem that can present as a spot in the vision is a macular problem. The macula is the part of the eye that is most sensitive where actually most of our useful vision takes place. Swelling in the macula from a condition called Central Serous Retinopathy can cause a spot to appear in your vision. For more information on this condition, look here.

The most common reason for the spots being a result of a problem in the optic nerve is glaucoma. Glaucoma is an often undiagnosed condition, mainly because there are no symptoms early in the disease. So, why would an optic nerve problem like glaucoma cause you to see a spot in your vision? I’m so glad you asked!

To keep it simple, you can think of your vision like a paint by number picture with each nerve in the eye responsible for a point of the picture. If you lose a nerve, you lose a spot. Since, nerves don’t typically regenerate, once you lose it it is gone and that spot in the picture with it. Lose one nerve cell, no big deal. Lose a group and we have more of a problem. To compound the picture, the brain is a marvelous thing. It has the capability to (and often does) fill in missing parts of the picture, so you may have to lose a lot of cells before you can begin to detect a problem. If you think “no way, I’d obviously see it” think again. Check this out.

Anyway, what this means is that by the time the patient comes in saying they have a spot in their vision from an optic nerve problem like glaucoma, it is generally more advanced. This is one of the main reasons we recommend frequent eye exams. The risk of glaucoma increases with age, thus even though everything is fine one year, it may present the next.

“So, how would a spot from glaucoma differ from say a harmless floater?” Wow, that is a great question and shows you are thinking about this! Typically, the reason why we call it a floater is because the spot “moves” independently in the eye. When someone notices the spot and they move their eye, the spot from a floater generally lags behind then catches up when the eye stops moving. This is because the floater is suspended in the vitreous and it will move a little differently than the eye. In an optic nerve problem however, the spot will track exactly with the eye since it is, as we said above, a problem with a specific spot in the “picture” of your vision that is missing. So if a patient says “the spot is always this far from the center of my vision and always in this direction from center” I get a lot more concerned that I may be dealing with a problem of the optic nerve or “transfer function” of the eye. Glaucoma is the most common cause but anything that can disrupt the signal from the eye to the back of the brain could be the culprit. Some of the more serious causes include strokes, tumors, and multiple sclerosis.

Lastly, a problem in the occipital cortex (back of the brain) can cause a problem with spots, although generally a problem there is associated with a much larger defect (typically half of your vision). Again, the most likely cause would be a stroke.

So, we have covered some of the basics of floaters. I hope this has given you a little more insight from a provider’s aspect on what we are looking for as we tackle the symptoms of floaters. Fortunately, most times we can smile and provide reassurance which is what I hope this 2 part series has done for you. BTW, I almost forgot. If your floater looks like this:

It’s probably just from buying bitcoin at 19,000 a coin and staring at the computer as it has lost ½ it’s value.