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LASIK Night Vision and Dry Eye

When considering LASIK one must also account for potential adverse outcome.  Fortunately, there are very few negative outcome and most are resolved over short time.  There are complication that happen at the time of the surgery, ones that linger in the short recovery phase (first 3 months) and then long term outcomes that may last permanently.

The complication at the time of the surgery, depend on what technique is used.  The issues concerning blade LASIK vs. blade-free IntraLase LASIK are discussed on a separate page.  Here we'll address issues related to IntraLase LASIK as performed by Dr. Ash at Modesto Eye Center.

Two of the most concerning long term adverse outcomes for most patient are the night time vision and dry eyes.  We'll discussed them here one by one, but please keep in mind that if one's eyes are dry, it will lead to night time visual difficulties.  So they tend to go hand in hand.


Night Vision Misnomer

Nighttime vision may often be overlooked when discussing LASIK eye surgery.  Many times glares and halos are mentioned as possibilities, but that is where it all stops.  Most patients who have had LASIK surgery are so happy with their daytime vision that they accept the impurities of their night vision.  However, night driving presents one of the most visually demanding task that we ever perform.

Not All LASIK Surgeries Are Created Equal

Night Driving Simulatorstudy by Steve Schallhorn, MD, et. al., published in the April 2009 issue ofOphthalmology, the official publication of the American Academy of Ophthalmology compared night time results of the standard Blade microkeratome conventional LASIK with the CustomVue Blade-Free IntraLase LASIK eye surgery (iLASIK). Patients treated at the US Naval Medical Center in San Diego, CA, with corrections of -4.50 D to -6.00 D were tested before LASIK and 6 months after LASIK in a Night Driving Simulator. They were scored on ability to recognize signs, see pedestrians, etc. An example from Dr. Schallhorn's 2007 Binkhorst Lecture is seen on the right.

In the group of patients that had the Blade Conventional LASIK eye surgery, only 79% achieved 20/20 vision without correction. On the Night Diving Simulator32 to 38% had a clinically relevant loss of performance, while only 2 to 7% had some improvement.

 



iLASIK is shown to be superior

Whereas, patients that had the iLASIK procedure (CustomVue with Blade-Free IntraLase Method),91% achieved 20/20 vision without correction. On the Night Driving Simulator 0 to 3% had a clinically relevant loss of performance and11 to 33% had an improvement.

 


Not All 20/20 visions are equal

Snellen Chart

As you can see in the above figure not all LASIK surgeries are created equal and not all 20/20 vision is the same. In the above image both charts are seen at 20/20 "quantity level." However, only the image on the right has the desired "quality."The term 20/20 refers to a way of measuring vision on a standard Snellen Chart. Dr. Hermann Snellen in 1862 (yes, at the time of the Civil War), developed a 100% contrast sensitivity black letters on white background chart. This ignores the capacity to recognize different shades of white, shades of yellow, gray, blue, ... Vision can be measured in Snellen Acuity, Contrast Sensitivity, Color Sensitivity and Recognition, Frequency doubling, field of vision, and more. Nighttime vision and driving present some of the most visually demanding tasks. The study above proves that iLASIK is the best procedure to preserve and possibly improve the capacity of individuals to see. This is the reason why even after FDA approved LASIK, it took 12 years until the US military finally allowed the TopGun pilots, Air Force pilots, and NASA Astronauts to have only the iLASIK procedure, and none other.


Dry eyes is one of the most dreaded side effects of LASIK surgery.  Even though most patients eventually recover, there are few who suffer long term.  Recovery, however, is directly tied to the technology used to perform the surgery. 

A study discovered an enormous difference in patients’ recovery from dry eyes following a LASIK procedure using Metal Blade Microkeratome as opposed to LASIK procedures using IntraLase Femtosecond Laser.  Steve Wilson and others at the Cole Eye Institute, Cleveland Clinic, in Ohio, performed the study and their results are presented in the table below.  Whereas 46% of Blade Microkeratome LASIK patients had significant dry eyes, only 8% of patients who received IntraLase experienced dry eyes.

 

 

Metal Blade Microkeratome LASIK

IntraLase Femtosecond Laser LASIK

Dry Eyes at 1 Month
After LASIK

46%

8%

Significant enough Dry Eyes to require treatment with Restasis drops

24%

7%

 

At Northern California Laser Center, Dr. Ash has also found there are still few former patients who received LASIK using blade microkeratome that still suffer from dry eyes.  Yet, since 2007 when he converted exclusively to IntraLase, the worst cases of dry eyes tend to last no more than 6 months.  Most of Dr. Ash’s Modesto and Stockton LASIK patients have returned to their baseline by 1-3 months, and those that fared worst, had fully recovered by 6 months.  There are also many patients such as Geno, the former KHOP radio DJ, that did not find any further use for artificial tears 10 days after LASIK surgery.


Dry Eye Associated with laser in situ Keratomileusis: Mechanical microkeratome versus femtosecond laser.  Salomao MQ, Ambrosio R Jr, Wilson SE.  J Cataract Refract Surg. 2009 Oct;35(10):1756-60.  Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA



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