So that was #AskAnythingAugust! And ask you did – thank you! Here is a summary of the questions that were asked, and my attempt at the answers!
Colin on asked Facebook: Which is worst - short sighted or long sighted?
SKE: Emmetroptic (“20/20 vision”) is best!! That's a really difficult question, as it depends on what you would view as an advantage/disadvantage?
Low hyperopia (long-sightedness) means that you can see very well in the distance (to drive, etc) and up until your 40s can probably read fairly well unaided. This is because the lens in the eye is still quite flexible, so the muscles are able contract and bring your focus inwards to read (accommodation). Once presbyopia sets in, that's when you may start to need reading glasses for small print. This is probably the slightly more "liveable" of the two?
Myopic people have incredible attention to detail and can see things up close that most of us can only dream of! Imagine being able to take a clockwork watch apart and put it back together again with no need at all for a magnifying glass?! However, then imagine not being able to see clearly for more than an arms length in front of you? Not so appealing huh?
To be honest, in the extreme, neither is particularly pleasant, and in fact can be quite debilitating when uncorrected (without glasses). That is why I can't stress how important it is to get children's eyes tested early, BEFORE they start school.
We should all be able to recognise the signs: a child that always sits right on top of the television or holds books, toys, etc two inches away from their face (possible myopia?). I have known a child in practice who wasn't just shy, but nervous to the extreme. It turned out she was very long-sighted, so anyone that stood within six feet of her was a compete blur - no wonder she jumped every time a stranger went near her. When she put on her first pair of glasses, it was an absolute revelation! Videos like this are real:
Squints, dyslexia, colour-blindness, etc, can all be picked up during a routine eye examination, and although not all curable, early detection can make all the difference if any form of assistance or treatment is required.If there is an underlying, undiagnosed and/or uncorrected prescription, the child could start to struggle in class, possibly becoming unruly and disruptive as a result, and ultimately falling behind, totally unnecessarily.
Nick asked on Facebook: I somehow mysteriously cracked a lens on my fairly expensive Oakley sunglasses. Can they be repaired or should I buy new ones?
SKE: Oh dear LA cracked lens can't be repaired sadly. However, if it is still a current model then any Oakley stockist should be able to order you a replacement (I believe they are only sold in pairs). If this isn't possible, and although Oakley will swear otherwise, depending on the tint and curvature of the lenses, a specialised Opticians may be able to reglaze them for you? Obviously these won't be official "Oakley" lenses, but would do pretty much the same job and would no doubt be cheaper than a whole new pair?
Sam asked on Facebook: Does masturbating really make you blind?
SKE: I KNEW you were going to ask that question (again!) Sam! No, there is no evidence that masturbating makes you go blind, in fact that myth, and others like "it causes you to grow hair on the palms of your hands" or "it leads to impotence" have been debunked countless times. I think that's just what Mum's tell their little boys when they get fed up of washing "those" socks!?
However, here's an interesting little article that should keep you amused for 5 minutes!
@Obvious_Colonel asked on Twitter: Since my LASIK, my vision = perfect. But lately I have trouble with small print. What age is normal to need reading glasses?
SKE: "Presbyopia" - long sightedness caused by loss of elasticity of the lens in the eye - typically occurs in the 40's+, dependent somewhat on the base prescription.
@CLechleitner42 asked on Twitter: What to do (or not) if the wind drops a grain of sand or so in they eye? Rub? Tilt head? Flush with water?
SKE: DO NOT RUB!! If the foreign body is still in the eye, you may end up scratching the surface of the eye which can be infinitely more painful. Irrigation is the key! Ideally with a saline solution, although understandably you may not have this on your person at the time?!
The eye will most likely water quite a lot of it's own accord, in an attempt to flush the offending item out. Usually we do not recommend contact between water and the eye (especially if you're wearing contact lenses!) but if you still feel like the foreign body is in your eye, flushing with water should help to dislodge it. (Again, the eye will be probably be watering so much anyway it will flush away any nasty bacteria that may be lurking in the water!)
If the eye remains, or becomes increasingly sore/painful, you should get an Optometrist to look at it as soon as possible, as it may have actually scratched the surface of the eye. Depending on the severity the Optometrist may prescribe some antibiotic eye drops to prevent infection.
@_Seal asked on Twitter: When your prescription changes does your eyeball change shape?
SKE: Good question! The answer to which is no, not really. Once puberty is over, the physical size and shape of the eyeball is pretty much set. Just like you've grown as tall as you're ever going to be. However, as always, it's not quite that simple. Prescription altering changes generally occur within the eye, or sometimes the cornea itself (the very front "window" of the eye) can change shape.
Other than age, the main causes of prescription changes are fatigue, certain medications, trauma or injury, and overexposure to the outdoors (UV). These things can all lead to changes in the translucence of the lens inside the eye. Most happen slowly, naturally if you like, over the course of time, as the eye, like the rest of us, ages. The lens becomes increasingly cloudy and hardens so that the muscles can no longer manipulate it as easily (presbyopia – see an earlier Tweet). Conditions such as diabetes, glaucoma, cataracts and macular degeneration can also alter your prescription, affecting not only the lens, but the retina (the back of the eye) also.
If you have astigmatism, this too can change over time, in some people more than others, as it only reflects the shape of the cornea. Even a small change in the shape of the cornea can in some cases lead to a larger change in axis. This is generally nothing to be concerned about, providing your eyes are healthy. Keratoconus is a condition in which structural changes within the cornea cause it to thin and change to a more conical shape, which can cause a substantial distortion of vision.
But don’t panic! If you are having your eyes tested as advised (every year or two) then your Optometrist will be keeping an eye on things (no pun intended!) and will tell you if they've found anything to be concerned about.
I actually had to research this. I thought I knew the answer and what I wanted to say, but sometimes it's difficult trying to get that across succinctly? I guess that's what makes a good teacher? However, I did learn a thing or two myself, such as: some studies have shown that people who move their eyes in a certain direction a lot, like scanning columns of numbers, will develop certain kinds of astigmatism. And, that high amounts of astigmatism are commonly found in groups with lower socio-economic status, poor diets, etc! See? You're never too old to learn! Thanks Lizzie!
Colin on asked Facebook: Why are there variations in eye colours? Some people have green eyes whilst others have blue. Was this in relation to evolution purposes?
SKE: Woah! Sounds so simple, but tough question?! Might have to quote Google for a bit here…
Eye colour is a bit complex in terms of “genetics”. The colour of human eyes is not dictated by a single gene like many other traits, but instead is considered a polygenic trait, or a “polygenic phenotype character” (try saying that after a couple of sherbets?!). This means that there are in fact several different genes on various chromosomes that carry information about what eye colour an individual will possess. These genes, when expressed, blend together to make various shades of the different colours we see on show today.
Eye colour itself is determined by two distinct factors: 1) the pigmentation of the iris; and 2) the frequency-dependence of the scattering of light determined by the level of cloudiness of the stroma (the upper layer of fibrovascular tissue of the iris).
(This bit I didn’t know!) In humans, the pigmentation of the iris actually varies from light brown to black, depending on: 1) the concentration of melanin in the iris pigment epithelium (located on the back of the iris), 2) the melanin content within the iris stroma (located at the front of the iris), and 3) the cellular density of the stroma. The appearance of blue and green, as well as hazel eyes, results from the Tyndall scattering of light in the stroma (a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering). Neither blue nor green pigments are ever present in the human iris or ocular fluid, eye color is thus an instance of structural colour and varies depending on the lighting conditions, especially for lighter-colored eyes.
There is a very close connection between eye colour and skin colour. Our earliest human ancestors are believed to have come from the continent of Africa, where the equator cuts directly through, i.e. it receives almost direct sunlight all year long. This direct sunlight, associated ultraviolet rays, and warm temperatures is thought to have brought about the natural selection of dark skin colour, and hence dark brown, almost black coloured eyes. Pigments, like melanin in the skin, protect against the harmful rays of the sun. This kept individuals with darker skin alive longer, and as a result they reproduce and pass down the dark skinned genes to their offspring.
Even though brown eyes are still considered to be the most dominant of all eye colours, we all know there are several different eye colours readily seen now in the global population of human beings. Why? Well, while evidence is still being collected, most scientists agree that lighter eye colours are as a result of a relaxation of the natural selection of darker skin tones. As our human ancestors began to migrate to various places around the world, the pressure for the selection of dark skin was not as intense and not particularly essential to the survival of those that settled in what are now the Western European nations. These much higher latitudes afforded different seasons and levels of direct sunlight nowhere near the likes of Africa. As a result, the genes that determine eye colour are likely to have mutated, which in turn created even more alleles available to combine together in the gene pool to create different eye colours.
Fascinating stuff huh?!
@_Seal asked on Twitter: What do all the numbers on your prescription mean?
SKE: I totally stole this from littlefoureyes.com! It’s American, as in the UK you won’t see OD or OS, only RIGHT or LEFT (or R & L). Also, British prescriptions are written in minus CYL format, but that’s a whole other story! It does however give you the general gist: