Night vision questions for glenn

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Night vision questions for glenn

Postby Pappy » Sun Mar 23, 2008 4:46 pm

Glenn (thanks for doing research for every one),

I have some night vision questions and trying to formulate the correct questions for my doc (PRK - 8 weeks ago next appointment this wednesday).

My daytime vision is probably 20/awesome. My low contrast vision seems to be getting better but I am noticing somethings. At dusk starburst seem to be the most prominent (and from checking my pupils in the rear view they are perhaps 4mm when this happens- obviosuly since I'm focusing they shrink up a little). I also notice that my right and left eye behave differently almost as if my prescription changes.

During extreme low light (pupil at full dialation), my vision feels fine as long as there are no direct light sources about but if there is say a streetlamp or a shaded window that additional light makes it feel like I need to put on glasses and again I notice a difference between how the two eyes see. My eyes also when this happen being to feel "dry" (don't feel this way during the day) and perhaps it's due to decreased blinking while my brain tries to sort out what it's seeing.

So with that pre-amble and knowing I'm in the late stages of early healing what questions should I be asking about this night vision differencial. Would this be HOA related, ablation zone related, pupil size?

I'm debating asking for a script for some Alphagan-P to see if this corrects some of the issues but perhaps that might not be the only resolution (besides time). So primarily I'm thining of a short term crutch as my healing progresses.

Ideas and suggestions welcomed.

Thanks Glenn.
Pappy
 
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Re: Night vision questions for glenn

Postby LasikExpert » Sun Mar 23, 2008 8:19 pm

Pappy wrote:I also notice that my right and left eye behave differently almost as if my prescription changes.


That is very likely exactly what is happening. Your "prescription changes" because the refractive error at the outer edge of your cornea is different thatn in the center. When you pupils become large the multiple refractive errors combine, often presenting as halos around light sources or starbursting.

Starbursting commonly indicates an irregular corneal surface.

Pappy wrote:During extreme low light (pupil at full dialation), my vision feels fine as long as there are no direct light sources about but if there is say a streetlamp or a shaded window that additional light makes it feel like I need to put on glasses and again I notice a difference between how the two eyes see.


As the light causes changes in your pupil size, the mix of the different refractive errors changes.

Think of your vision as a bull’s-eye target. The center is perfect vision. Going out from center rings two and three also have good vision. Ring four has poor vision. Rings five, six and seven have good vision. Ring eight has poor vision. Let's assume all rings are the same size.

When your pupils are small and light passing only through rings 1-3 reaches inside the eye and is "seen", 100% of your vision is great. When the pupil dilates and adds poor vision from ring 4, 25% of the light entering the eye is poor (ring 4 bad, 1,2 & 3 good). When the pupils dilate more and ring 5 is added, now 20% of your vision is bad (ring 4 bad, rings 1, 2, 3 & 5 good). Your vision improves. You can see how vision quality could fluctuate up and down depending upon the pupil size.

Yes, I know that ring 4 would have a greater mass than ring 3 because of the circumference of the ring, but I'm only trying to give an example here.

Pappy wrote:I'm debating asking for a script for some Alphagan-P to see if this corrects some of the issues...


Undoubtedly it would help if, in the example above, it kept your pupils to rings 1, 2 & 3. But if it allowed ring 4 to get in but didn't allow rings 5 & 6, then you could be in that 25% vision poor bracket. The only way to know is to try it.


Pappy wrote:So primarily I'm thining of a short term crutch as my healing progresses.


Exactly. Assuming you don't have an odd allergy, your healing will be the same with Alphagan P or without.
Glenn Hagele
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Lasik Info &
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I am not a doctor.
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Postby Pappy » Sun Mar 30, 2008 5:41 pm

Thanks glenn since I posted this my starburst have been diminishing and only really occur prior to low light adjustment of my pupils so your ring explanation is very appropriate.

At max width, little to no starburst and min width none at some point in between some and that's changing.

Probably due to being off steroids now for 2 weeks and entering my 11th week post surgery all this initial healing is settleling down.

Here's hoping it continues down this trend.
Pappy
 
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Joined: Wed Feb 06, 2008 3:40 pm


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