Optic Nerve & the Importance of an Eye Check 👀

Apologies for the slightly heavy text, but I wanted to express my concern on this matter because we only have one set of eyes. Each eye has an optic nerve connecting it to your brain. It allows you to see what you can see by transmitting electrical signals or impulses to your brain. Damage to your optic nerve may result in vision loss or blindness.

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I had been putting off my eye test until my partner said to just go get it done since I needed to order more contacts. My partner says his eyesight is near 20/20 vision, but I wanted him to get an eye test done too. So the deal was I go if he goes. So off we went to get our eyes tested. We thought it would just be the standard test of seeing if you can read the letters on each line.

However our optometrist tested the pressure in our eyes and checked the health of them too. More importantly, probably because I skipped my last visual field test, we were told we were both sitting near the danger zone. Which danger zone you may ask? The danger of developing glaucoma due to the level of our optic nerve damage. If the optic nerve is severely damaged you could develop glaucoma – irreversible blindness.

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What was great was he explained to both of us what it is, how it is measured and the importance of coming in for regular tests to monitor it. I knew the optometrist always checks the health of our eyes too, but I didn’t know this is what they looked for. Until it was explained we were within the limits, set by the government, that requires the optometrist to encourage us to come for regular checks to keep an eye on it and address it if it worsens. So we were booked in for a visual field test for the following week with the other optometrist since the machine was located in the other room.

However before leaving, we were sent to another room to take photos of our eyes inside. Here are the images of my eyes. When the photos were taken, all you could see in each eye were bright flashes of alternating colours with outlines of the blood vessels. During that time, I swear I felt like a robot where your eyes become screens. It was pretty cool.

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So I waited over a week before posting about it because I wanted to do some research, get the test done, talk more about it with the optometrist and take photos of the results. It turns out my last (and first) visual field test was back in 2013. I also had an eye pressure test back then at the same time. The reason why I had these tests done in the first place was due to my blurred vision even with the correct eye prescription.

It was discovered the nasal spray I had been using, to keep my allergies under control, contained cortisone (steroid). I had been using the spray for about 6-10 months. The optometrist said he has a patient that had been using a nasal spray that contained cortisone for 2 years to keep her allergies under control too. She ended up with glaucoma at the age of 18. I stopped using the spray immediately and my vision went back to normal.

There have been various research on the correlation between the use of nasal sprays containing cortisone and increase of eye pressure/optic nerve damage. Although there has been mixed results.

Clearly, it appears that there is no consensus as to whether nasal steroids truly impact IOP. Several studies declare them safe for usage in patients, whereas there is also strong evidence supporting their effect in increasing IOP. Source

Even though it is declared safe to use, I decided to avoid using if I could.

So I had both tests done to check the state of my eyes. It turns out I had ocular hypertension, higher than normal pressure in my eyes. The normal range is between 12 - 21 mmHg. This puts pressure in the nerve fibres which may cause damage. My visual field test results were not too bad, but I was booked in for another test the following year to monitor it. I ended up rescheduling then cancelling my appointment and continued to put it off each year. I thought I was fine because I had stopped using the spray and my eye sight was stable.

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It was not until our recent check-up did I learn the true seriousness and lack of awareness of this matter. It was explained to us the normal cupping percentage (the middle circle part of the optic disk) should be 33.33%.

Mine was 60% and my partner was at 80%.

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Here I drew on a close up image of my eye to show you how they calculate the cupping percentage. The blue circle denotes the optic disk area and green circle the cupping area.

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Because this was my partner’s first test, we opted to retest in 6 months before looking at whether he needs to be referred to a specialist. This is because we do not know if he was born with 80% cupping or there has been nerve damage.

There is no way of telling if someone has nerve damage until an eye test is done to check the health of the eyes. Someone could have perfect vision but could have a big cupping, just like my partner.

Our optometrist said we are still young and glaucoma does not happen overnight, it is a slow process. We need to monitor it with visual field tests. A visual field test does not just help detect/monitor glaucoma, it can check for other diseases and even brain tumor.

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The Test

The visual field test required us to block one eye with an eye patch then place our head into position in front of what looks like a large dish which you stare into. The lights are then turned off and you will stare at a dot in the middle. You will be given a button to press each time you see a dot appear in your field of vision. But you must keep your eye glued to the middle dot, don’t go looking around. The test is to see if you can see particular areas in your field of vision, central and peripheral.

Remember to blink as normal, else your eyes will start to water and you start seeing things hahaha. But the advice we got was to just press the button if you think you saw something but you were not sure. Because some dots that appear will be fainter than others. Darn I should have taken a picture of the machine because I can’t seem to find a copyright free image of the one my optometrist has.

People with glaucoma will have their peripheral vision affected first. Hence by completing regular visual field tests, it will help monitor and detect the changes to your field of vision.

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Anyways, time to check out my results.

Here are my visual field test results for my right eye. The left image is from the test done back in 2013 and the right is the current test. I've circled the missed targets for easier comparison. We can see there was a big improvement to the one spot that I had missed back in 2013; going from -27 to -9. Although now I have a few extra spots I have missed too.

Oh and if you were wondering what that BS is, that is the blind-spot, where your optic nerve is located. there are no photo receptors here hence why you cannot see anything in this area.

Here are my visual field test results for my left eye. The left image is from 2013 and right 2018. This time no improvement to the existing missed spot. And there are a few extra missed spots too.

Overall comparing to my age group, my results were ok. My optometrist also showed me the raw data and explained to me what certain parts meant. It was really interesting but scary at the same time because the raw data was checking for any defects. He explained to me not many people are aware of the importance of checking the health of your eyes. Even the GP doesn’t seem to advise their patients to get their eye checked he said. Usually older people come into to get their eyes checked because they discovered their vision is really blurred. By that time it is too late, something could have been done to control it if it was detected earlier. Eye drops could have been prescribed to help reduce the pressure in your eyes. A specialist could have arranged a scan of all the layers of your retina to spot underlying problems. There's also surgery or medication to help slow down the process.

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So my message I want to relay to my readers out there is to get your eyes checked even if your eyesight is fine. It is more about getting the health of your eyes checked. If your optometrist does not say anything about it, ask. Ask about the health of your eyes, ask about the nerve damage if it is ok, and ask for an eye pressure test if they didn’t give you one. Normal pressure should be between 12 - 21 mmHg. Though some literature state it is between 10 - 22 mmHg.

There are various reason why your eye pressure could increase or decrease. It just happens my damage was done mainly by the prolonged use of the nasal spray containing cortisone. I wish I had known about the importance earlier, because once the damage is done, it is done. The cupping size will never reduce, there is no regeneration of your optic nerves. Although there are research being done to change this, but why not avoid it via early detection if you can?

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Note: Unless cited, all other images belong to @supersoju; also permission has been sought from my optometrist to take photos of my results to post up

References:

Both of my optometrists
Eye tests
What is a Visual Field Test?
What is Cortisone?
Optic Nerve Cupping
Visual Field Test
The Relationship of Intranasal Steroids to Intraocular Pressure
Optical Coherence Tomography – OCT 3D Eye Scan
Restoring Vision: Retinal Nerve Cell Regeneration
Changes in Eye Pressure — Causes and Treatment Options
Optic Nerve: Definition & Function