Read Refractive Surgery Outlook
February Double Feature:
By Linda Roach, Contributing Writer
Rejection Risk Is Higher for Some Groups After DSEK
Corneal allograft recipients might experience fewer rejection episodes if surgeons included African heritage -- or perhaps dark skin pigmentation in any population group -- in the list of factors they use to identify high-risk patients, a 2009 study of DSEK patients suggests.
However, the news that African-Americans are five times as likely to reject a corneal graft as Caucasians has been slow to spread, says Kenneth M. Goins, MD, professor of clinical ophthalmology and director of the Cornea and External Disease Service at the University of Iowa.
Limited Awareness
Dr. Goins delivered a paper on screening patients for keratoplasty techniques at the Refractive Surgery Subspecialty Day: ISRS Annual meeting, held last fall in San Francisco. "Since then, I've received many comments that people didn't realize that African-Americans had a higher rate of rejection in general. So it was good that I mentioned that in my talk," Dr. Goins said.
Nearly a year ago, Francis W. Price Jr, MD et al. reported that the relative risk of rejection after DSEK was five times higher for African-American patients compared with Caucasians (p = 0.0002). [1]
This study was the first statistical analysis to confirm clinical observations by Dr. Goins and others that black patients have greater inflammation and suffer more rejection episodes after corneal grafts of all types.
Dr. Price is scheduled to speak on this topic in March at the annual meeting of Britain's cornea society, The Bowman Club.
Pigmentation at Fault?
The researchers analyzed results in 598 DSEK eyes with at least three months of follow-up. They speculated that extra pigmentation might be associated with greater inflammation and subsequent rejection.
Although direct data to support an association are limited, the Price study suggests that other dark-skinned population groups also might be at risk, said Bruce Allan, MD, FRCS, a corneal specialist and consultant ophthalmic surgeon at Moorfields Eye Hospital in London.
"We probably need to factor ethnic background into our tailoring of post-operative topical steroid regimens after corneal transplantation - an important implication of his study," Dr. Allan said.
Inflammation May Be Key
"Wound healing appears to be unregulated generally in patients with darker skin pigmentation," he noted. "Trabeculectomy failure rates and pterygium recurrence rates are higher, and keloid scarring is more common.”
"Glaucoma surgeons are aware of the higher incidence of trabeculectomy failure in black populations," agreed Alaa M. El Danasoury, MD, medical director and chief of refractive surgery at Magrabi Eye & Ear Hospital, Jeddah, Saudi Arabia. "To my knowledge corneal surgeons are much less aware of the higher risk of graft failure in these ethnic groups."
Both Dr. Allan and Dr. Goins have adjusted their post-op anti-inflammatory regimens in these patient groups to compensate for race/ethnicity.
More Medication, Longer
"We certainly use a stronger topical steroid regimen routinely in black and South Asian cataract patients in London," Dr. Allan said. "But this is based on clinical experience rather than clear evidence."
Dr. Goins believes that higher, prolonged dosing with topical corticosteroids is indicated for African-American patients after DSEK or PK. Before the Price paper, he based this decision on clinical experience with this patient population while he was at the University of Chicago.
"You just have to do it," he said. "I use prednisolone acetate QID for 3 months, TID for 3 months, BID for 3 months, and once per day thereafter. If I'm really concerned about a patient's risk, I am more likely to add topical cyclosporine 1% or 2% twice daily as a supplement to the steroids, and I continue both medications indefinitely."
Risk for All Endothelial Grafts
Dr. El-Danasoury said he has not adjusted his post-op care based on ethnicity or race, however, because he considers all recipients of endothelial cell grafts at high risk for rejection.
"My post-endothelial grafts plan of care is lifelong, with regular follow-ups and continuous patient education, especially on the early symptoms of endothelial rejection," Dr. El-Danasoury said. "For pseudophakic patients I prescribe one drop of prednisolone acetate at bedtime with regular monitoring of intraocular pressure."
His Rx: Individualized Regimens
In an interview, Dr. Price said hopes the findings of last year's study will percolate into clinical practice soon.
"Just as we're now making the corneal surgeries we do disease-specific, we probably need to take a look at tailoring the post-op regimen to the patient's relative risk for a rejection episode," Dr. Price said.
"This is an important public health issue," he added. "However if physicians are more diligent and do things like increasing both the dosing of topical corticosteroids and the frequency of post operative examinations in these high risk individuals, we should be able to change the risk profile."
1. Price MO, Jordan CS, Moore G, Price FW. Graft rejection episodes after Descemet stripping with endothelial keratoplasty: part two: the statistical analysis of probability and risk factors. Br J Ophthalmol. 2009;93(3):391-395. PubMed
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High Myopia: Lens or Laser Surgery?
Careful screening and advances in refractive surgery techniques now make it possible to achieve excellent post-operative UCVA even in highly myopic eyes, a leading U.S. surgeon told colleagues at the 2010 Hawaiian Eye Meeting.
The key lies in deciding whether to do excimer laser or lens-based surgery, based on the patient's age, ocular anatomy, level of refractive error, and overall visual needs, said Karl G. Stonecipher, MD, medical director of the TLC Vision Center in Greensboro and Raleigh, NC.
Clinical experience with the three available surgical choices – wavefront-optimized LASIK, phakic intraocular lenses, and clear lens extraction with presbyopic IOL implantation – shows that each is best-suited to certain types of patient characteristics, Dr. Stonecipher said.
After Age 45, RLE is Better
Instead of offering LASIK as routine, highly myopic patients older than age 45 should be offered refractive lens exchange and presbyopic IOL implants or monovision, he said.
"RLE is looking better and better for patients 45 and above," Dr. Stonecipher said. "It is more expensive than LASIK, and sometimes they can't afford it, but these patients are eager to find a presbyopic solution to their refractive error. And the complications can be kept low."
Most patients emerge with a distance UCVA equal to or better than their pre-op BCVA, along with improved near vision, he said.
Retinal Pre-Screening
"It is the better option, as long as the retinal ophthalmologist first examines them and approves them for surgery," Dr. Stonecipher said.
His practice found that 57 percent of patients referred to a retinal subspecialist required preoperative treatment, but were then able to undergo RLE. Cystoid macular edema developed in 0.6 percent of eyes, and one had a retinal detachment.
While modern techniques appear to have lowered the YAG capsulotomy rate after cataract surgery to less than 10 percent, the average is around 36 percent overall in RLE patients, he said. This may be related to the younger age of the RLE population.
Before Age 45, Anatomy is Key
For high myopes younger than age 45, ocular anatomy and the astigmatism level (in the United States) are the primary considerations in deciding between a phakic IOL and LASIK, he said.
"If there's a thin cornea or the patient is otherwise not suitable for a corneal procedure, then a phakic 'implantable contact lens' (Visian ICL, Staar Surgical) is the best option," he said. "But if the chamber depth is below 3 mm, it gets to be a challenge to implant the ICL."
Currently, astigmatism >1D also prevents U.S. surgeons from using the ICL in many high myopes, because the toric version is unavailable.
In U.S., No ICL for Astigmatism
"In any eye with more than 1D of astigmatism, I start treating with LASIK as long as the corneal anatomy allows, even though an ICL probably would produce a better quality of vision than most excimer lasers would," Dr. Stonecipher said. "But a toric version of the ICL has not gained FDA approval yet."
The visual quality with the ICL has led some European and South American surgeons to embrace it as the preferred refractive surgical option for myopia as low as -6.5D, he noted. But, newer laser ablation profiles and faster excimer lasers can perform -6D to -12D LASIK corrections with excellent visual results, he said.
Data on High-Myopia LASIK
Dr. Stonecipher also presented data from procedures performed with the Allegretto Wave Eye-Q Excimer Laser (Alcon), including:
- In 72 LASIK eyes (0 to -10D sphere; ?3.5D cylinder), the correlation coefficient for attempted vs. achieved corrections was 0.994 for sphere and 0.959 for cylinder. If you look at the -6D to -12D group, the correlation coefficient for attempted versus achieved corrections was 0.997 for sphere and 0.894 for cylinder.
- In 132 eyes (refractive targets: 0 to -7D), 99 percent of eyes had distance UCVA of 20/20 at 46 to 120 days postop.
- In 15 eyes corrected for -6D to -12D of myopia and >3D cylinder), 100 percent had distance UCVA of 20/20 at that time point. A third of them gained 1 line of VA compared to their pre-op BCVA.
Technology Matters
Dr. Stonecipher credited the tight refractive results to femtosecond-laser flaps, wavefront-optimization of the excimer ablation profiles, and short treatment times (2 seconds per diopter) made possible by the Wave Eye-Q's 400 Hz repetition rate.
"The laser you use really matters when you are treating -7D and above. You can't just use older excimer lasers," warns Dr. Stonecipher. "If you choose to do LASIK, don't revert back to older laser platforms or older laser ablation profiles. The patient’s quality of vision will suffer with induced spherical aberrations and the outcomes won’t be as good as what we are seeing with the newer lasers platforms."
CONFLICT OF INTEREST INFORMATION:
Dr. Stonecipher receives travel grants and compensation as a consultant, speaker and researcher from several ophthalmic companies. These include Alcon, Wavelight, Nidek, Bausch & Lomb, Oasis Medical, Allergan, Ista Pharmaceuticals and Inspire Pharmaceuticals.
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