Be Awake 4-5 hours before Catatact IOL Measurements

Anyone notice decrease in myopia upon waking?  I have seen up to two lines improvement on the Stellen chart upon waking in the morning.  Vision is noticeably sharper for the first two hours, and tails off to normal at 4 to 5 hours after waking.  This is the likely reason my Crystalens both resulted in an intial 20/40 vision, ~-0.75D.  They usually target 20/25, but I recall having the eye measurements 2 hours or less after waking when vision is sharper.  Why don't the optometrists and ophthalmologists recommend the patient be awake for at least 4 hours or so prior to getting measured.

Granted, the reduced myopia can vary among patients.  But this was documented on Chart 6, p441 in
TR. AM. OPHTH. SOC., vol. 68, 1970, "Hydration of the Cornea", P. Thomas Manchester.  25 volunteers were measured, showing reduction of myopia from 0 to +0.37D.  With a larger set, this could easily range from 0 to +0.50D improvement.

Oxygen levels are significantly reduced during sleep, causing cornea swelling -- and reduced near sightedness.  My own tests seem to show a fairly large time constant for the cornea and visual acuity returning to worse normal vision.  

Yet, I have not found a single reference elsewhere on the web, whether surgeon web sites or patient postings.  I had been wondering why after getting the Crystalens IOLs that I commonly tested at 20/25 at home in the morning, whereas, 20/40 in the doctors offices.  In the afternoon or evening at home, I would test 20/40.  I was also able to test the eye irrigation theory documented in the report, in which the oil film is washed away causing corneal drying over the next hour, and reduced myopia, too.

Am I the only one who has made this observation, other than the MD who wrote the 1970 paper???  Personally, I would advise anyone getting fitted for any cataract IOL to be awake 4-5 hours, to be sure the cornea shape has fully returned to normal.   My optometrist was unaware; and my surgeon never mentioned this, and I forgot to mention on my last visit.

[darad]

Here's the web link to the 1970 technical paper,
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1310387/pdf/taos00031-0438.pdf

[Ray T Oyakawa, MD]

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[darad]

Can you comment on the waking factor, which affects the cornea shape from nighttime swelling?  You comment was "-".  My personal testing from waking onward has shown up to two lines improvement in myopia, i.e. perhaps +0.37D to +0.50D.  This would definitely affect the IOL prescription if measured too soon after waking.  Yet not a single web posting on this consideration, since the 1970 technical publication.