Q: I have a 47-year-old male patient who successfully underwent LASIK 4.5 years ago. Now, he needs an enhancement for increased myopia O.U. What should I look for when I determine if hes able to undergo a procedureand, which procedure should I recommend? Is a flap lift advisable at this point?

A: Assess the cause of the myopic progression, says Jay S. Pepose, M.D., Ph.D., medical director of the Pepose Vision Institute in St. Louis, Mo. Compare the topographies to look for interval changes that would be consistent with regression, perform a cycloplegic refraction to obviate the effect of accommodation and perform a dilated exam to look for lenticular changes.

The cause of the progression may or may not be best handled with an enhancement. For example, oil drop cataracts could be causing this patients myopic shift, and they arent easy to spot.1 Oil drop cataracts can be subtle, says Dr. Pepose. If a lens change or early cataract is the cause, then LASIK retreatment may not be the optimal choicethese changes may progress and the outcome may not be stable. Instead, consider phacoemulsification or fitting the patient with a contact lens as the lenticular change progresses, he says.1

Another very important piece of information that you need to know: Does he have diabetes? Uncontrolled diabetes can also cause a myopic shift, Dr. Pepose says. And, he adds, cataract formation is related to glycation and oxidative stress levels.2 In patients who have diabetes, LASIK may be performed only if the diabetes is well controlled.3 If it is not, the patients outcome will most likely not be stable. But, even in cases when the LASIK procedure can be safely performed, an enhancement would still be likely be required for optimal correction.3

Examine the patients ocular surface. Dry eye, blepharitis and rosacea can affect visual quality, notes Dr. Pepose. Additionally, a flap lift will sever the corneal nerves in the flap and create more dryness, so it is important to assess tear film break-up time and rose bengal staining before considering a retreatment with another flap lift.

Epithelial ingrowth may be a arisk for this patient, given his age and the maount of time since his original procedure. Photo courtesy: Jay S. Pepose, M.D., Ph.D.

Once youve determined the cause of myopic progression and assessed the patients ocular health, you need to decide what procedure the patient can safely undergo. At 4.5 years after LASIK, is a flap lift a safe procedure for the patient? Care must be taken not to tear the flap, says Dr. Pepose. Also, epithelial ingrowth is a risk for this patient because of two conditions: his age and the amount of time that has passed since his original procedure.4 Ingrowth is a risk, Dr. Pepose says, However, the overall rate of ingrowth that requires surgical removal is relatively low following meticulous removal of the epithelium surrounding the flap edge during the procedure.

If there is concern about repeating a flap lift, consider a surface treatment, such as photorefractive keratectomy (PRK). Surface treatment will induce less dryness postoperatively, says Dr. Pepose, but the patient will have a slower recovery. Make sure to take into consideration the patients corneal thickness and residual stromal bed thickness. Many surgeons try to maintain a residual stromal bed thickness of 250m or greater, notes Dr. Pepose. And, if a surface treatment is performed, consider the off-label intraoperative use of mitomycin C, in an effort to prevent haze formation second to ablation over a prior LASIK flap.5

Evaluate the treatments impact on this patients near acuity. And, before any procedure is undertaken, examine this patients peripheral retina for asymptomatic retinal breaks.

 

1. Soong HK, Dastjerdi MH. Lenticular myopia from oil-drop cataract: a cautionary tale in laser in situ keratomileusis. J Cataract Refract Surg 2004 Nov;30(11):2438-40.

2. Chiu J, Taylor A. Nutritional antioxidants and age-related cataract and maculopathy. Exp Eye Res 2007 Feb;84(2):229-45.

3. Halkiadakis I, Belfair N, Gimbel HV. LASIK in patients with diabetes. J Cataract Refract Surg 2005 Oct;31(10):1895-8.

4. Chan CC, Boxer Wachler BS. Comparison of the effects of LASIK retreatment techniques on epithelial ingrowth rates. Ophthalmology 2007 Apr;114(4):640-2.

5. Neira-Zalentein W, Moilanen JA, Tuisku IS, et al. PRK retreatment after LASIK. J Refract Surg 2008 Sep;24(7):710-2.