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Intracorneal inlays offer best of both worlds
Early cases show inlay’s potential, in light of the early stage of the learning curve.
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PORTO, Portugal — Intracorneal inlays offer the best of both worlds in that they are extraocular like LASIK and reversible like phakic IOLs, according to one surgeon. Antonio Marinho, MD, PhD, reported on early results of intracorneal inlays at the European Society of Cataract and Refractive Surgeons meeting in Amsterdam.
“This new technology seems very pro mising, but to survive the test of time, it has to match the accuracy and predictability of LASIK and phakic IOLs,” he said.
Dr. Marinho described the Perma Vi s ion corneal inlay (Anamed) as a thin disk made of a soft material. The inlays are 5-mm discs for hyperopia from +1 D to +6 D, and 7-mm discs with a 2-mm central hole for myopia from –5 D to –12 D.
Simple technique
Dr. Marinho described the technique as very simple.
“We use a [Bausch & Lomb] Hansa tome microkeratome to create a flap, which we then lift just as if we are doing a LASIK. Instead of doing a laser ablation, however, we then place the disc on the stroma,” he said.
The two most important aspects of placement, according to Dr. Marinho, are centration and placing the disc right side up. Because the inlay is so thin, it is easy to confuse which side is the top and which is the bottom.
“It is critical that the right side be placed top-up. This is one of the complications still associated with this technique,” he said.
Next, he dries the inlay carefully with a Merocel sponge to promote adhesion to the stroma, then gently irrigates the back of the flap.
“We cannot do a generous irrigation like some do in LASIK surgery because that will cause this disc to dislocate,” he said.
Early outcomes
So far, Dr. Marinho has implanted the inlays in four eyes: three hyperopic and one myopic. Two of the hyperopic eyes started out +3.5 D and achieved plano, and one started out +6 D and ended up +1 D. The myope ended up with an undercorrection of –3 D, which Dr. Marinho attributes to the possibility that the inlay was put in upside down.
“As visual acuity is concerned, we lost one line in two hyperopes. We lost three lines in the myope. This, of course, tells us that probably we did not put this in the right way. We could improve these results as the learning curve develops,” he said.
Three of the cases resulted in slight infranasal decentrations.
“This was the most important complication besides loss of lines. This would account also from the loss of lines of vision,” he added.
The technology is in the early stages of development, and problems remain that must be addressed, he reported. The original cartridge that contained the disc made it difficult to ascertain which side was the correct one to be placed up.
“Because of this, it made it hard to know the right position and it was possible to put it in upside down as I think we did in our myopic case,” he said.
A new delivery system currently in development is “very user-friendly and completely avoids this problem of upside down discs,” he said.
Decentration, which is also an ongoing challenge, is present at 24 hours postop and is nonprogressing.
“We attribute that to the pressure of the hinge. We use an 8.5-mm flap and a superior hinge, and we think the superior hinge may not be suitable for this technique,” he said.
In upcoming cases, Dr. Marinho planned to use larger flaps and either nasal or inferior hinges.
“The pressure of the hinge, I think, is the most important part of decentration,” he said.
Additionally, Dr. Marinho suggested that having the patient rest for 24 hours postop might eliminate the possibility of disc movement.
For Your Information:
- Antonio Marinho, MD, PhD, can be reached at Rua Eugenio de Castro, 170-41 Porto, 4100-225 Portugal; (351) 22-200-0692; fax: (351) 22-609-3345; e-mail: marin@mail.telepac.pt. Dr. Marinho has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- Anamed Inc. can be reached at 25651 Atlantic Ocean Drive, Suite A1, Lake Forest, CA 92630; (949) 707-2740; fax: (949) 707-2744.