Contact Lens vs Spectacles

[chrisyeo]

Hi,

When I was in Mersing 2 weeks back, I decided to put on a pair of disposable contact lens for my first stargazing experience with contact lens. Here's my experience:



I have been wearing spectacle for the longest time, and have never had the good fortune to look at a star-filled sky with with just my naked eyes alone. For those with perfect eyesight, appreciate it.

Now the basic problem with spectacles for stargazing is that the additional piece of glass will cut out some light (but not by much), but more importantly, it doesn't allow you to see the whole sky clearly, but only about 60 or 70% directly in front of you. Additionally, it doesn't allow you to put your eye directly to the eyepiece, which prevents you from seeing the whole FOV on some eyepieces.

For people with astigmatism, such as me, viewing without spectacles on an eyepiece is possible, but will not be perfectly sharp as astigmatism defects cannot be corrected by the eyepiece. One option is to put on the diotrix filter by Televue that corrects for astigmatism.

Another option is to go for Lasik surgery. This is a risky non-reversible procedure in which some people have reported blurred night vision.

Ok, finally, on to my experience. When I put on the contact lens, I experienced this sensation of 'wow, the universe out there is so big'. But, I also experienced that the stars tended to exhibit 'coma'. At times, they appeared sharp, but with slight shifts, tails of light could be seen jutting out. This is similar to the effect of looking at streetlights at night with contacts or spectacles, and seeing tails of light coming out.

Initially, this was distracting, but as I explored with the telescope, I realised that this effect was almost unnoticable at the eyepiece. It was wonderful to stargaze with your eye right on the eyepiece and still see sharp stars. The 'spacewalk' effect was evident.

Looking up naked eye, I began to see that meteors were popping up all over the sky. With spectacles, I probably would have seen what was only within a more limited view of 45-50degrees in front. For me, this increased breadth of vision more than made up for the slight coma-like effect.

All in all, I believe that contacts lens provided a whole new stargazing experience for astigmatism sufferers like me. Any person wearing spectacles will benefit from the increased field of vision and the freedom of viewing the whole sky 'just with your own eyes'. Do give it try and tell me what you think!

In Summary:

Cons:
1. Slight coma-like effect visible.
2. Possible issues associated with normal contact lens wear

Pros:
1. Wider field of vision.
2. No eye-relief problems at eyepiece.
3. 1-day disposable contacts are available cheaply.
4. More freedom of movement.
5. Ability to experience 'whole-sky' and 'spacewalk' effects.

Clear Skies!

[Canopus Lim]

Thanks for the review.

Actually astigmatism is a real bother for low power viewing since the exit pupil will be large. Other ways to solve that is to wear spectacles corrected for both spherical(short/long sightedness) and astigmatism but this require long eye relief eyepieces which do cost a lot. My spectacles are corrected for that, but it still cannot give the sharpest point like stars when seen on the eyepiece (at low magnification) compared with higher magnification and smaller exit pupil. Another alternative I think is to use SCTs/ MCTs and long focal length telescopes to minimize the exit pupil btu at the expense of the maximum TFOV. For example my C5 is the best for my eyes as it is f/10. A 35mm eyepiece giving a field of 1.7 degrees will have exit pupil of 3.5mm which is good for my eyes when wearing spectacles.

I think wearing contact lenses for astigmatism is a way to help when viewing through the eyepiece. Also, with the contact lens, the entire FOV can be seen which is important.

Alternatively, one could buy long focal length TV plossls that support the Dioptrix. I think that combination would give very good image (the TV plossls are probably the best plossls around) and not cost too much money.

[rlow]

Another option is to go for Lasik surgery. This is a risky non-reversible procedure in which some people have reported blurred night vision.

There is another issue for those who undergo Lasik surgery: some reported night vision that is affected by flaring etc. This was covered in an S&T article last year.

[kayheem]

Hmmm...guys like Gavin who wear contact lenses should give their input here. In theory, they should not experience coma-like effects.

Chris, what type of contact lens did you use? What type of contact lens did you use (hard/soft)? Did you get it fitted by a contact lens practitioner or did you just buy a pair of disposable ones over the counter?

The effects you saw may be due to ill-fitting contact lens. I am just guessing as I have not observed with contact lenses before.

[klutz]

In theory, they should not experience coma-like effects.

Well, I'm a contact lens user too. I've worn both hard & soft, monthly, yearly and daily contact lenses for years. I've tried different brands, with and without astig corrections. And all gave me the same effect as Chris.

And yes, I've seen and felt the difference between viewing with glasses and viewing thru contact lenses. The latter proves to be more friendly, as I can go as near to the eyepieces than with glasses.

My short-sightedness is -7.0 per eye, and astig is approx. 200 degree each. Currently, my soft lenses do not correct astig and I often need to strain my eyes to see. But the view is still definately better than wearing glasses... Glasses are a hindrance. Or you can say I'm bias

I hate being shortsighted, really. Those who has perfect eyesight should really appreciate it. I envy them much.

Had been searching for info on Lasik for months. Hell, the side effect is definately more than poor night vision. For ppl with shortsightedness more than -3.0, lasik may not fully correct your vision. And if it doesn't, the patient wouldn't be able to wear contact lenses anymore. They'll have to stick with glasses to correct the balance. And usually, Lasik patients will suffer from long sightedness after 40...

Sigh.. I am waiting for scientist to improve on Lasik treatment... perhaps it'll take another 5 - 8yrs?

One more con on wearing contact lenses actually. Eyes get dry easily for some. And mishandling of the lenses can cause cornea ulcers.

One more pro though. It doesn't make the wearer's eyes look small ( for those with high power like me ) haha

[kayheem]

Hi Klutz,
I am not surprised that you experience problems as your moderate astigmatism is not corrected. You should use toric lenses which correct the astig and see if you still have problems.

FYI, patients do not suffer from long-sightedness after 40 just because they underwent LASIK. Practically everyone after the age of 40 will have problems seeing near if they are corrected for distance vision. This problem is called presbyopia ('old-sighted') and not 'long-sighted'.

The confusion arises as both end up using convex lenses for correction.

[alvinsclee]

Myopia = short-sighted
Hypermetropia = long-sighted
Presbyopia = old-sighted

Astrogenic photophobia = the result of spending too much time in near-total darkness such that even moonlight becomes a blinding spotlight (many DSO photographers are in this category)

As a former optician, I can tell you that we have a rule-of-thumb for presbyopia: add +1.00 diopter for every 10 years after 40, who will normally start with about +1.00 diopter... hence a 50 year-old person will have about +2.00 diopter onwards, a 60 year-old person will have about +3.00 diopter onwards... etc.

Some people believed that short-sighted people will suffer less from the effects of presbyopia (due to compensatory optical effects)... this is not true, of course. Our ocular lenses harden with age and our ciliary muscles weakened too... all of us can't escape from a time when we have to wear progressive lenses (at least better-looking than bifocals). I'm wearing one... +1.50 diopter... no need to guess my age, hahaha.

[klutz]

Hi Kayheem,

I've worn toric lenses for 2 years. It's called "hard lens" rite? It did correct my astig, but still, I tend to see "tails" when I stare at the stars. I gave up the hard lenses becos I dun feel comfortable in them, and it's much more difficult to "pluck" out than soft lenses.

Maybe it's my eyes' problem?

And I've always thought "long-sightedness" is = to "old-sightedness"... :roll:

[zong]

EWWW!

Sorry for my input there. I personally don't like the feeling of something "inside" my eyes. I'm sticking to spectacles no matter what they say, even if contacts eventually prove to be better when improvements are made to them

Yes I don't like spectacles either, because of the limited vision I get from the eyepieces. Sometimes when i scramble for that little bit more view, my spectacles usually get "oiled" by my face and i have to clean it quickly afterwards. So troublesome..

I've read a few reviews that Lasik surgery for some stargazers turned out to be a total disaster as the "colours" that could originally be seen from the telescope view somehow became distorted after Lasik. And because it's a non-reversible procedure, somehow they regret and they posted their views online so people would not fall for that. Most reviews by skywatchers do not favour Lasik surgery.

Guess i'll be a 4-eye-guy for a long long time to come ^^

[kayheem]

Klutz, toric is not equal to hard lenses. Toric lenses correct for astigmatism, and can be found in soft lenses. Hard lenses are simply made of a harder material.

Lenses which are not well-fitted can move around the eye and may be the reason for the coma-like effect. I am not sure on this as I do not wear contact lenses when observing.