Rapid astigmatism change.

[Rincer]

I posted here some weeks ago about a sudden change in sphere prescription in one of my eyes (from -1.5 to 0.0). The Ophthalmologist couldn't find a reason for it. And thinks I should just go ahead a get a new prescription, but now I am noticing changes in astigmatism as well. I judge it by the halos that I am seeing, they used to all be down and to the right, but now I noticed one appearing in the opposite direction. It is not as 'spread out' as the other ones, but is more 'solid'.

What could possibly cause that?

I also remember when the Dr was measuring my ocular pressure, the eye with the vision change was at 20, which I believe is borderline normal (normal range being 10-21). The other eye was 17. Could a rise in ocular pressure perhaps be changing the shape of the cornea and thus causing all these changes?

[Rincer]

Got it, thank you also sent you a message with a link to my corneal topography scan.

[wanlien3]

I would agree that there is no need for any immediate treatment. I will send you a message about the doctors in your area.

[Rincer]

Hi

Thank you. I am still waiting for Dr's office to get back to me regarding the aberrometer results. They don't seem to be very responsive.

I went to my current ophthalmologist, because he was close by and could see my right away. Now that he ruled out any need for immediate treatment I am reseaching to find an ophthalmologist close to where I live that would be best suited to handle my case. I feel that what happened to me is not very common.

I am in San Francisco bay area, if you have any recommendations I would love to hear them.

[wanlien3]

What you describe is exactly what I would expect with the bright text on dark screen.

If or when the halos/blurriness starts bothering you a lot, then you could try the rigid gas permeable lenses. The other thing is to repeat the topographies at some point and monitor the corneal shape in case it changes further with time.

If the corneal shape stays the same and the halos get worse, we could be more sure about the lens as a cause of your symptoms...

Another way to confirm the source of your problem is to fit you with rigid gas permeable lenses anyway (this is done with trial lenses which most optometrists and some ophthalmologists have in their clinics). If the halos/blurriness disappears with the trial rigid lens in your eye, then it cannot be related to the lens or 'cataract'.

[Rincer]

Also when reading the acuity chart uncorrected with the right eye, some letters were easier to see than others. For example T H and O were easy, but an F looked a bit like a P.

20/25 was big enugh to read all the letters, 20/20 I could make out maybe 60%, on 20/15, I was pretty sure I saw an O and a T, but they were kind of flickering in and out of focus.

Also big difference between optometrist and ophthalmologist offices, Optometrist had a really clear well illuminated chart with letters far apart. Ophthalmologists was really unevenly illuminated reflecting from an old mirror. The mirror could be tilted to adjust for patient height I guess and the chart had letters very close together so was harder to read.

Anyway maybe I sould just stop complaining and be happy to have this natural monovision, that for my age is probably not too bad as you say.

[Rincer]

When I say text 'looks blurry' the blur is only on the right and bottom of the letters, top and left look sharp.

[Rincer]

Dr's diagnosis was that its a combination of 'irregular astigmatism and cataract', but he couldn't actually see the cataract. He deduced it by subtracting the corneal error from the total error. Also he believes it happened over a period of several months, before I noticed it, but I doubt that very much, I usually spend 90% of my day without my glasses, because they are distance only and I can not see well with them when working, I am a software engineer. There was definitely a sudden difference between left and right.

I have also been researching higher order aberrations, the one that most closely matches what I am seeing is 'smearing' in the opposite direction of my astigmatism axis in that eye. Light produces stronger smearing, thats why bright text on dark tv screen looks more blurry than dark on white

[wanlien3]

Hi, if you are referring to spectacles, then no, there are no spectacle lenses which can correct higher order aberrations. The best quality vision would be provided with rigid gas permeable contact lenses, although given how good your unaided vision is I can understand why you aren't particularly interested in contacts.

It still isn't particularly clear why your sphere changed so much, although it is  related to changes in your corneal shape or lens shape.

[Rincer]

Hi again,

I found my prescription from 6 years ago, which was the last time I had an eye exam, before this sudden hyperopic shift in the right eye.

OD -1.62 -0.87 113
OS -1.87 -0.50 067

So looks like the left is very steady and the big change in the right is the sphere.

I do believe I always had that 'smear' or coma type aberration in the right eye, but it was much harder to detect since without glasses it was overpowered by the error in sphere and with glasses it was too small to see since the astigmatism correction does improve it a lot.

Now when I don't wear any correction in the right eye, it is much more apparent since the sphere error is not masking it anymore.

I do not want lasik or contacts, is there any lens technology in existence that might be able to correct it or at least do a better job than the regular astigmatism correction?

[Rincer]

Yes, I've been trying to get used to it, my left seems to be the dominant eye which makes it a bit harder I believe.

It took a few weeks, but now at far distances I have no problem. In fact even though left eye is really blurry by itself, it still seems to contribute to the overall definition.

One situation where I still have an issue is reading bright text on a dark background from a TV screen about 15 feet away.The left eye still seems to be trying to take over and when I close it I see much better. However reading dark text on a bright background is ok.

[wanlien3]

The strength of the prescription suggests that, whatever it is, it's pretty mild. Now you have monovision, which is a pretty good situation to be in if you can get used to it. No need to wear glasses, since your right eye is good for distance, and your left eye is good for near.

[Rincer]

Yes I see what you are saying, does the actual strength of the prescription tell anything about the condition?

The prescription for that eye now is
OD  +0.50-0.75 X 79
                                                    
The other eye is
OS -2.00-0.50 X 53

Up until about 6 weeks ago they used to be about the same.

Visual acuity for distance vision in the affected eye actually increased dramatically. Its 20/25 uncorrected. But as I mentioned before I do get the daily swings, I think the astigmatism doesn't actually change now, on the days when my vision is more blurry the halos just appear bigger.

Still waiting for drs office to respond.

[wanlien3]

A skewed asymmetric bowtie pattern like the no 10 figure is suggestive of a keratoconus type picture. It is even more likely to be abnormal if the right and left eyes are very different.

Regardless of whether you call it keratoconus or forme fruste keratoconus, it is a good idea to get the maps repeated in about 6 months or earlier if you notice any further worsening of your vision.

It is true that keratoconus tends to become more stable as the patient gets older, but this is not always true all the time.

Any comments from your doctor about the corneal topographies?

[Rincer]

That asymmetrical skewed axis bowtie does indeed seem to match Keratoconus pattern. But now I am not really sure if that is what I saw... It was definitely asymmetrical, but I am not too sure about the skewed axis.

Also I am 48 so if I had it then it should've stopped progressing by now.

[Rincer]

Hi, I am still waiting for the drs office to reply to my request of sending me the corneal topogrpahy images, but I found a chart online that shows a bowtie pattern similar to what I remember seeing at their office. Its the number 10 in the table:

http://www.keratoconus.com/resources/DiagnosingKeratoconusandPatientsofRisk.pdf

Except that it's rotated to the left so that the top part of the bowtie is pointing at about 11 o'clock and the bottom part is shorter, but wider.

It seems to match the shape and direction of the halos that I am seeing.

[wanlien3]

That's a pretty good corneal thickness. Which makes it less likely that you have this condition called keratoconus, although some people have a subclinical form called 'forme fruste keratoconus' which may still give unusual halos...

[Rincer]

So this morning I had my corneal thickness measured and it was 580, so I think that rules out IOP as a source of daily changes in vision.

[Rincer]

Thank you, that actually makes a lot of sense explaining my daily variations in vision. Since experiencing the hyperopic shift in my right eye, I feel like I have been putting a lot of strain on it, since I still haven't gotten my new prescription.

My near vision in it is not as good anymore and far vision hasn't been corrected for astigmatism. So I am definitely overworking the ciliary muscle. I am 48.  

[wanlien3]

Hi, I suspect that your old glasses, being over-powered (over-minused), are forcing you to accommodate. Part of the accommodative response is to constrict the pupil, and when you have a smaller pupil the effects of aberrations in general are reduced. I am not sure why your halos fluctuate so much, but one possibility is fluctuation in your pupil size, due to variations in lighting or accommodation.

Prolonged excessive accommodative effort will make your eyes tired, and when the ciliary muscles are fatigued especially if you are near or over 40 years of age, vision will just go blurry when they give up after a while.

It is difficult to be sure what the exact problem is, but I would strongly recommend you get a corneal topography +/- aberrometry. Any corneal surgeon or LASIK surgeon will have a corneal topographer.

[Rincer]

So to sum up, the 'strong' halo at 11 o'clock in my drawing has been getting longer this whole week and as a result I felt like my overall visual acuity in that eye has been getting progressively worse. But this morning I woke up and the halo is back to its 'normal' size. I hope this all makes sense.

[Rincer]

To wanlien3:

I experienced a hyperopic shift overall, but have daily variations in vision within a limited range, which I thought could be due to IOP?

Also some explanation for the picture I drew:
The circle is the light source.
The darkness of the lines around it is proportional to the intensity of the halos. (black = intense, gray = soft)

[Rincer]

To SoftwareDeveloper:
I ordered the set, but its coming from China, so will be a fe weeks since I chose free shipping. They ruled out diabetes even though my blood sugar was slighly higher than normal range. Also if it was blood sugar related then the problem would've manifested itself in both eyes. Cataracts make a lot of sens to me since everybody in my family had them, but they didnt find any, so I am not sure what more I can do. I have an apt with this ophthalmologist on Tuesday where he is going to scan my eyes for higher order abberations, I decided to let him finish his diagnosis before moving on. Thanks very much for the link to the articles about IOP its very informative and pretty much falls in line with the daily changes I am experiencing in my vision.

To wanlien3:
My ophthalmologist operates out of 2 offices and the equipment for measuring higher order abberations was in his other office, he is going to bring it on my next visit. Not sure if its capabale of doing corneal topography or not. Regarding the abberations I am seeing, reason why I think its astigmatism is because looking through my old prescription lense fixes it almost completely, there is still a very small halo at the bottom, that is hard to notice. But the sphere power in that lense is now wrong and makes my vision more blurry overall.

Here is my drawing of the halo effect I am seeing:
http://imgur.com/QLDBCjz

[wanlien3]

A difference in ocular pressure of a few mmHg should not cause a significant refractive change.

I previously saw a post LASIK patient who developed glaucoma, and he had slight myopia when the intraocular pressure was high (prior to treatment).

Post treatment, when the IOP was reduced by about 6mmHg, he experienced a hyperopic shift which presumably is due to the lower pressure being associated with slight corneal flattening. So I don't think in your case the pressure has anything to do with the refractive shift, especially since if anything, an increase in IOP should be associated with a myopic shift rather than a hyperopic shift.

[wanlien3]

'Halos', especially oddly shaped ones, are generally due to what we call higher order aberrations. Asymmetrical ones, such as those being down and to the right, are due to 'coma-like' aberrations. These are due to irregularities in the focusing media of the eye, of which the two most important ones are the cornea and the crystalline lens.

If your doctor did not mention cataract previously, I would check to see whether corneal topography was done. I have seen patients with problems like keratoconus where, because of the inferior position of the cone, they experienced asymmetrical inferior halos corresponding to the position of the cone, which was ultimately the cause of the coma-like aberrations.