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Pediatric double IOL implantation may control refractive, deprivation amblyopia
A HEMA and AcrySof lens combination is implanted. The HEMA lens is then removed at 2 years of age.
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EUGENE, Ore. — Multiple IOL implantation with phased removal may control deprivation amblyopia and refractive amblyopia. The combination of a HEMA lens and an Alcon AcrySof is ideal for these children, according to the developer of the technique.
“Stabilizing the refractive status after cataract surgery can be achieved in a number of ways. Dr. Mehta’s concept involves implanting a permanent lens made of acrylic. Then, a removable lens made of pure HEMA is placed in front of this. He found that the HEMA lens produces no adhesions and can be removed easily. The HEMA lens is produced in the shape of an inverted dome, making intracapsular placement easier,” said Richard S. Hoffman, MD. He discussed a study performed by Keiki R. Mehta, MD, of Mumbai, India.
The lens is made of hydroxyethylmethacrylate crossed with other polymers. It has a refractive index of 1.4 and a high water or saline content. It is temperature-resistant and has excellent light transmission, Dr. Hoffman said.
The HEMA lens is made by IOL Tech India Limited, which according to Dr. Hoffman is a World Health Organization-certified company. The Food and Drug Administration has not approved the lens. It has a 9.5-mm diameter, a 5-mm optic, a 6.8-mm base curve with a bevel on the external aspect permitting easier bag entry, and it can be easily folded for insertion or removal through a 3.4-mm incision, he said.
“The IOL is selected under general anesthesia by measuring corneal curvature with an autokeratometer and taking axial length measurements with an A-scan. The total IOL power is then calculated using the SRK-T formula,” he said.
Extrapolation to 2 years of age is made based on these readings. For example, an infant at 3 months with an IOL power calculated at 28 D to 30 D will need only a 23 D lens at 2 years, Dr. Hoffman said. An AcrySof lens with this extrapolated, anticipated IOL power is then placed in the bag. The residual power in a HEMA lens is placed in front of the AcrySof.
The HEMA lens is removed when the combination IOL power reaches a refraction of –4.
“For example, an infant implanted at 3 months with a 29 D piggyback combination will reach –4 at approximately 18 months of age. At that time, the HEMA IOL is re moved. Dr. Mehta uses a rule of 4, because a variation of 4 D from emmetropia rarely induces significant amblyopia,” he explained.
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Implantation of folded HEMA
IOL. The AcrySof lens in situ in the capsular bag. 
Both IOLs are stable.
Due to the beveled edge of the IOL, insertion under the rhexis is
easy.The procedure
Surgery is performed under general anesthesia. A scleral incision is used for infants younger than 8 months, a corneal incision for children older than 8 months. A continuous curvilinear capsulorrhexis is performed followed by aspiration of the cataract. A posterior rhexis is then performed with Utrata forceps. An anterior dry vitrectomy is also performed.
The incision is widened to 3.8 mm. A Monarch injector is used to implant the AcrySof lens. The first 11 cases were performed with an AcrySof MA30. Subsequent cases used a single-piece AcrySof lens.
The HEMA IOL is inserted using a folder. Both lenses are placed in the bag, and the wound is closed with a 10-0 nylon suture.
Study
Dr. Mehta’s study included 27 eyes of 16 infants. Five infants had unilateral implantation, and 11 had bilateral. The age at implantation ranged from 2 to 15 months, and the age of HEMA IOL explantation ranged from 18 to 28 months, with more than half of the infants explanted at 28 months.
Complications included corneal abrasions, shallow anterior chamber and iritis. There were two instances of pupil capture with the HEMA IOL, 10 instances of raised IOP — three of which required surgery — and five instances of mild postoperative hyphema, he said.
Future study
According to David R. Stager Jr., MD, who also discussed the study, “This is the largest series reported of its kind, and the authors should be commended for having a minimum of 3 years of follow-up in all patients. This new approach minimizes the dependence on contact lenses by offering immediate, near-emmetropic pseudo phakic correction and a solution to the imminent and often large myopic shift these infants will experience by explantation of one of the lenses at months or years later.”
However, he said, “The authors in no way convinced us, nor attempt to argue, that this method is superior to conventional methods. No visual acuity outcomes are presented. There’s no control group. It is a retrospective review of selected patients, and the data may be tainted with bias.”
Dr. Stager said he believes that temporary polypseudophakia is worthy of future investigation, and he hopes that Dr. Mehta continues to explore this “uncharted territory.”
For Your Information:
- Richard S. Hoffman, MD, can be reached at Drs. Fine, Hoffman & Packer, 1550 Oak St., Suite 5, Eugene, OR 97401; (541) 687-2110; fax: (541) 484-3883; e-mail: rshoffman@finemd.com. Dr. Hoffman has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- David R. Stager Jr., MD, can be reached at 8201 Preston Road, Suite 140-A, Dallas, TX 75225; (214) 369-6434; fax: (214) 696-6273; e-mail: stagerdr@aol.com. Dr. Stager has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- Keiki R. Mehta, MD, can be reached at Mehta Int. Eye Institute, 147 Shahid Bhagat Singh Rd., Mumbai 400005, India; (91) 22-215-0082; fax: (91) 22-215-0433; e-mail: keiki_mehta@yahoo.com.