Microincision one-piece IOL has quick visual recovery, low induced astigmatism

The lens also offers easy implantation, according to a surgeon.

Hiroko Bissen-Miyajima

A one-piece hydrophobic acrylic IOL designed for insertion through a small incision results in quick rehabilitation of postoperative vision with low surgically induced astigmatism, according to a study presented at the annual meeting of the American Society of Cataract and Refractive Surgery.

In the study, the microincision iMICS1 IOL (Hoya Surgical Optics) was implanted through an incision in the capsular bag using Hoya’s manual-load cartridge, but a pre-loading system will soon be available to make implantation a simpler process, Hiroko Bissen-Miyajima, MD, said in an e-mail interview with Ocular Surgery News.

According to the study results, 38 eyes of 29 patients had mean uncorrected distance visual acuity just above 0.00 logMAR 1 day after surgery. By 1 week, 0.00 logMAR was achieved and maintained through 1 month of follow-up. Corrected visual acuity remained consistent, with little change throughout the study.

“Most IOLs provide good outcomes. The beauty of this particular IOL is the ease of implantation and early stabilization of refraction. This benefit will bring quick rehabilitation of postoperative vision, which means good uncorrected visual acuity from 1 day postoperatively,” Dr. Bissen-Miyajima said.

Less induced astigmatism

Almost all patients can benefit from microincision surgery, Dr. Bissen-Miyajima said, because a smaller incision results in less surgically induced astigmatism and more stable visual acuity. The final incision size after insertion of the iMICS1 IOL was 2 mm in 53% of eyes, 2.1 mm in 21%, 1.9 mm in 21% and 2.2 mm in 5%.

After surgery, patients had a stable corneal astigmatism of –0.709 D at 1 day, –0.64 D at 1 week and –0.642 at 1 month. Overall, mean surgically induced astigmatism was 0.12 D.

“Doctors who are satisfied with small-incision surgery of 3 mm or 2.75 mm should try the microincision surgery,” Dr. Bissen-Miyajima said. “Surgical technique is comparable; however, a 30% reduction of incision width is obvious at slit lamp examination and leads to less induced astigmatism.”

Surgical technique

The technique to implant this IOL is easy, Dr. Bissen-Miyajima said. Phacoemulsification should be done through a microincision, and the IOL should be implanted in the capsular bag. In the study, a 1.8-mm to 2.2-mm incision was made in the temporal clear cornea with a 5-mm to 5.5-mm capsulorrhexis.

The one-piece lens is contraindicated in patients who require sulcus implantation. In cases of weak zonules, lens subluxation or luxation, or rupture of the posterior capsule during the procedure, a different lens should be used.

“The behavior of an IOL inside the eye is different depending on the material,” Dr. Bissen-Miyajima said. “This IOL expands inside the eye slower than the AcrySof lens (Alcon), which can be a benefit or a drawback.”

To implant the IOL, the cartridge should be inserted in the eye and the lens pushed forward. To get a good outcome with this lens, it is crucial for surgeons to know the ideal method of implantation.

“The wound-assisted technique of putting the cartridge at the site of incision and using the incision tunnel as a path does not fit for this IOL,” Dr. Bissen-Miyajima said. “If one doesn’t have the equipment — the ultrasound tip and sleeve that go through less than a 2-mm incision size — the lens can be implanted through a larger incision of 2 mm or 3 mm under the current technique.”

A toric design of the iMICS1 IOL is under clinical trial in Japan and should be available in Europe this year. – by Stephanie Vasta

• Hiroko Bissen-Miyajima, MD, PhD, can be reached at the Department of Ophthalmology, Tokyo Dental College, Suidobashi Hospital, 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan; 81-3-3262-3421; e-mail: bissen@tdc.ac.jp.
• Disclosure: Dr. Bissen-Miyajima is a paid consultant for Hoya.