Inconsistent refraction analysis before LASIK.

Research your concerns in this forum or post your questions if you have had Lasik, IntraLasik, PRK, LASEK, Epi-Lasik, RLE, or P-IOL within the past three months.

Inconsistent refraction analysis before LASIK.

Postby marcalans » Tue Aug 22, 2006 3:48 am

This is a brief history of my refraction analysis before LASIK over recent years:

2003:
Humphrey autorefactor results
OD: -6.25, +1.00 x 84
OS: -6.50, +1.50 x 82
Subjective refraction results
OD: -6.50, +1.50 x 75
OS: -6.50, +1.50 x 94

2004:
Humphrey autorefactor results
OD: -6.00, +0.75 x 81
OS: -6.00, +.75 x 90
Subjective refraction results
OD: -6.25, +1.25 x 75
OS: -6.50, +1.50 x 90

NEW OPHTHALMOLOGIST (LASIK surgeon)

2005:
Humphrey autorefactor results
OD: -5.25, -0.75 x 168
OS: -4.75, -1.25 x 170
Subjective refraction results
OD: -5.25, -1.25 x 173
OS: -5.25, -1.25 x 170

2006 (one week before LASIK):
Humphrey autorefactor results
OD: -5.25, -1.25 x 173
OS: -4.75, -1.25 x 170
Subjective refraction results
OD: -5.25, -1.25 x 173
OS: -5.00, -1.50 x 10

2006 (Day of LASIK surgery - VISX CustomVue WaveScan results):
OD: -4.85, -1.27 x 172
OS: -4.63, -1.08 x 178

Physician adjusted correction used for Wavefront-guided LASIK:
OD: -4.83, -1.11 x 172
OS: -4.63, -0.95 x 178

QUESTION:
Looking back at my refraction values, I don’t understand why there is so much inconsistency between 2003/2004 and 2005/2006 (two different ophthalmologists). According to these values, my myopia improved approximately a full diopter during this time.

WaveScan measurement the day of LASIK surgery indicates even less myopia and astigmatism. The surgeon proceeded with the surgery using the approximate WaveScan values.

As a result, three weeks after surgery, I am now grossly undercorrected with residual astigmatism and my surgeon claims that I will need an “enhancement.” I am also seeing large halos and starbursts around bright lights at night.

When I asked the surgeon why he used the WaveScan values, considering my other refraction results were much higher, he replied that the WaveScan values are much more accurate. Obviously, they are NOT more accurate because I can’t see nearly as I could with my eyeglass prescription based on my 2004 subjective refaction results.

If I were a surgeon and saw such a discrepancy, it would raise a red flag and I would want to take additional measurements. What could account for this discrepancy and what should I be asking this physician?

Thanks.
marcalans
 
Posts: 3
Joined: Tue Aug 22, 2006 3:45 am

Re: Inconsistent refraction analysis before LASIK.

Postby LasikExpert » Tue Aug 22, 2006 5:08 am

The discrepancy is not that great. 0.25 diopters is normal fluctuation for human vision. You can blink three times and make that much change in refraction. The difference between your 2005 subjective refraction and the physician adjusted wavefront correction is only about 1/3rd of a diopter.

Why you become less myopic over the years is impossible for me to guess.

It is much easier to enhance a myopic (nearsighted, shortsighted) undercorrection than an overcorrection into hyperopia (farsighted, longsighted) vision. If the surgeon is going to error on the side of caution, it would be to undercorrect.

It would be helpful to know your current postoperative prescription, your age, when you had surgery, and if you are wearing corrective lenses while you heal.
Glenn Hagele
Volunteer Executive Director
USAEyes

Lasik Info &
Lasik Doctor Certification

I am not a doctor.
LasikExpert
Site Admin
 
Posts: 3309
Joined: Fri May 12, 2006 6:43 am
Location: California

Postby marcalans » Tue Aug 22, 2006 6:18 am

Thank you for your response.

I am a 52 yr. old male.
CustomVue IntraLasik on August 1, 2006
Intralase + Visx Star S4 excimer laser.

My postop prescription is as follows:
OD: -0.25, -0.75 x 169
OS: plano, -0.75 x 174

Dilated pupil size (Colvard pupillometer) = 4 mm

Opitical zone = 6.5 x 6 mm

Ablation zone = 8.0 mm

I am currently not wearing corrective lenses, but have ordered them because I’m having difficulty with astigmatism. Not sure if they will help at all with the higher order aberrations (profound halos and starbursts).

Surgeon can’t offer any explanation for the higher order aberrations other than to say that I am healing. Experimented with Alphagan one night, but resulted in nothing but a tremendous headache, which lasted 24 hrs. I have copies of all my topography scans, but I don’t know how to use them to interpret decentered ablation, if that is at all possible.

I also don’t understand why my 2003/2004 refraction results include a positive number for the cylinder value, indicating hyperopic astigmatism and my 2005 and later values indicate myopic astigmatism.

Thanks.
marcalans
 
Posts: 3
Joined: Tue Aug 22, 2006 3:45 am

Postby LasikExpert » Tue Aug 22, 2006 11:05 pm

It is way too early to make a final judgement on your surgery outcome. Refractive surgery is more of a six month process than a 20-Minute Miracle. Your current astigmatism could explain some of the night vision problems. You may want to read about Lasik and Pupil Size. Your doctor may be interested in using the CLAPIKS technique to resolve the residual refractive error.

The difference in the prescriptions is because they are written in plus cylinder and minus cylinder. You can read about this at How To Read Eyeglass Prescription.
Glenn Hagele
Volunteer Executive Director
USAEyes

Lasik Info &
Lasik Doctor Certification

I am not a doctor.
LasikExpert
Site Admin
 
Posts: 3309
Joined: Fri May 12, 2006 6:43 am
Location: California

Postby maxxed » Wed Sep 20, 2006 3:06 am

Sorry to hear about your starburst and halos. I think you still had enough residual astigmatism when you last posted to cause some definate visual symptoms.

The changes in your refraction over the years may be explained by the fact that some people experience a hyperopic shift with age.

You can check this government study:

http://www.ncbi.nlm.nih.gov/entrez/quer ... t=Abstract

or Google something like "hyperopic shift with age"
maxxed
 
Posts: 7
Joined: Mon Sep 18, 2006 11:13 pm


Return to Just Had It

Who is online

Users browsing this forum: Google [Bot] and 2 guests

cron