Safer refractive IOLs to boost vision options for ametropes

Roibeard O’hÉineacháin
in Rome

INNOVATIVE new refractive IOLs now in clinical trials may be easier and safer to implant than current lenses and could provide ametropic patients with improved visual outcomes, according to researchers at the 7th ESCRS Winter Refractive Surgery meeting.

Among the new lenses is the ICARE (Corneal) refractive IOL, an angle-supported anterior chamber lens which can be inserted through a small incision, with a special haptic design to prevent angle erosion, Simonetta Morselli MD said.

The ICARE is a single piece injectable lens with an optical diameter of 5.75mm and an overall length of 12mm to 13.5mm. It can correct refractive errors from -20 D to
+10 D in increments of 0.25 D. The hydrophilic acrylic material of the lens has a UV filter and a refractive index of 1.465.

In a study involving 10 eyes of seven myopic patients, with a mean age of 34.8 years and a mean refractive error of -12.75 D, the postoperative mean spherical equivalent (SE) was -1.36 D at six months follow-up. In addition, the mean BCVA improved from 20/30 to 20/25 and there was no increase in mean cylinder.

The lens was well tolerated. Endothelial cell loss was 5% to 10% at eight months follow-up and none of the patients experienced postoperative inflammation.
“The thin material of the lens means that it can be injected through a small incision and will not induce astigmatism. Its haptics have a large 0.9mm contact area in the irido-corneal angle to prevent angle erosion. It also has minimal anterior vaulting to prevent endothelial cell loss,” she added.

Prior to implantation of the lens, Dr Morselli and her associates injected intracameral anaesthesia and a miotic agent into the eye. They then performed a 3.2mm incision and inserted the lens into the eye with an injector underneath high molecular weight viscoelastics. They positioned the haptic loops with a phaco manipulator and performed a surgical iridectomy.

Complications included IOL rotation. In two eyes this was associated with incorrect sizing. In the case of the third eye, the haptic loops became caught in the iridectomy. Decentration occurred in one eye and another had glare because the pupil diameter was larger than 6.0 mm. Another eye developed Fuch’s macular degeneration five months after surgery.

“The ICARE IOL is very easy to implant, gives a good refractive outcome and is well tolerated. We did have some problems calculating the exact size and because of the characteristics of the IOL, slight oversizing of the lens could be better than undersizing,” Dr Morselli said.

Two of the other phakic lenses described at the Rome meeting are modifications of older, already available phakic IOLs. One is the Artiflex lens, a flexible version of the Artisan “iris claw” lens which has a special injector that allows it to be implanted through a 3.2mm incision.

Jan GF Worst MD, inventor of the original Artisan lens and designer of the new Artiflex one, said implantation of the new lens with specially designed instruments induces less astigmatism than the Artisan and reduces the length of surgery.
The Artiflex lens has a 6.0mm optic and an overall length of 8.5mm.
The material of the optic is polysiloxane with a UV filter, a new generation silicone with a high refractive index.

Like the Artisan, the iris claw haptics of the Artiflex are made from PMMA. There is currently one model for myopia correction of –2.0 to –12 D. Hyperopic and toric models are under development.

Dr Worst noted that the new instruments for implantation of the lens are essentially standard surgical instruments which have been especially redesigned. They include a spatula adapted to introduce the flexible phakic IOL through a 3.2 mm incision and a new forceps for holding the haptic claws against the iris during enclavation without folding the lens and damaging the endothelium.

“The greatest risk of foldable anterior chamber lenses is the unfolding movement. The ARTIFLEX lens does not fold. The special design of the spatula allows the lens to be introduced in the anterior chamber in a stretched position through a small incision,” Dr Worst said.

To further enhance the precision of the surgery, Dr Worst has also developed a new technique for iris enclavation using a phaco aspiration cannula.
Dr Worst pointed out that the Artisan lens has been around for over 20 years, and in eyes followed from the earliest days of its implantation it has produced stable refractive results with only normal physiological endothelial cell loss.

“The flexible Artiflex phakic IOL will make refractive iris fixated lens implantation more accessible to ophthalmic surgeons, especially those with surgical experience in Artisan lens implantation,” Dr Worst said.
Belgian ophthalmologist, Camille Budo MD concurred with Dr Worst, pointing out that the original Artisan was introduced at a time when most ophthalmic surgeons were familiar with ECCE, together with the implantation of non-foldable IOLs.

“At that time we needed to suture the cornea after cataract operations. But young surgeons have little experience with sutures and they also need refractive lenses which are foldable like the ones they use for phaco procedures,” Dr Budo said.
He added that the contraindications for the Artiflex are the same for the classical Artisan and include anterior chamber depth less than 2.8mm and endothelial cell count of less than 2,100/mm2 and a pupil less than 6.0mm in diameter.

There is now about a year’s follow-up of the first aphakic implantations of the lens, he said. So far there have been good refractive results, with no endothelial cell loss and no rotation or movement of the lens, he noted.

A trial is now underway with the refractive version of the lens for myopia. The study will eventually include 420 patients and as many as 25 surgeons, with a follow-up of two years. He added that the results have also been good among the first eight phakic patients he has implanted with the lens earlier this year.
“The follow-up is very short at only two weeks but we think that the results will be as good as with the Artisan lens,” Dr Budo said.

He noted that he uses the same implantation technique as Dr Worst except that he uses an enclavation hook rather than aspiration for fixation of the claws on the iris. The implantation procedure begins by creating two paracenteses in the limbal region of the cornea with a diamond calibrated knife. Dr Budo then injects a miotic solution to constrict the pupil and injects viscoelastic.

“We always recommend a cohesive viscoelastic because it has no effect on the lens epithelial cells and is more easily removed than dispersive viscoelastics,” he said.
He then places the IOL on the implantation spatula, which grasps the haptic claws and causes the lens to fold slightly along the axis of the haptics. Then, keeping the conjunctiva covered to avoid any contact between the lens and the conjunctival flora, he slowly and gently brings the lens into the anterior chamber.

The withdrawal of the spatula automatically releases the IOL and allows it to unfold in the eye. He then uses the holding forceps and enclavation hook to bring the iris tissue into the claws of the lens.

“Implantation of the lens is an auto-folding process and an auto-unfolding process. The surgeon has full control of each stage of the procedure,” Dr Budo said.
George Baikoff MD, another pioneer of phakic IOL technology, described the results he has thus far achieved with his new bifocal anterior chamber implant, which is essentially a Vivarte anterior chamber lens modified to correct not only ametropia but presbyopia as well.

Like the Vivarte lens (Ciba Vision/IOLTech), which was launched in Europe in 2001, the new presbyopic implant is an anterior chamber angle-supported one-piece hydrophilic acrylic lens with rigid haptics and a foldable optic.
The new lens’ bifocal components consist of a central area for distance vision, a ring for near vision with a 2.5 D add and an additional ring for distance vision. The lenses are available for myopia up to –5.0 D and hyperopia up to + 5.0 D.
In 40 eyes of 25 patients who underwent implantation of the bifocal IOL, UCVA improved from a preoperative value of 20/40 to 20/25 after a follow-up of at least two months. In addition, 75% have a visual acuity of 20/30 and J1/J2 with no correction; 95% of patients can read Parinaud 2 (J1/J2) without correction; and nearly 80% no longer wear glasses.

Dr Baikoff noted that mean BCVA decreased slightly from a preoperative value of 0.99 to 0.96 postoperatively. He attributed the loss of acuity to the loss of contrast sensitivity, which in turn results from the reduced illumination of the distance image that is inherent to the design of all multifocal implants.

A temporary visual loss of two lines of BCVA occurred in one case but the patient recovered after four months. Dr Baikoff performed enhancement procedures with Lasik or PRK to correct small residual refractive errors in two eyes.
The mean SE after implantation of the lens was slightly myopic (-0.9D). However, Dr Baikoff said he has begun to achieve more accurate results since switching to the Holladay formula.

“The presbyopic refractive phakic IOL is a predictable, reproducible and reversible technique. For the moment, the results seem superior to the other surgical techniques for the treatment of presbyopia. It has to be noted however that there is a slight loss of BCVA in distant vision,”Dr Baikoff said.

The patients in the study included 20 hyperopes and five myopes aged between 45 and 75 years. All had an anterior chamber depth of at least 3.1mm and a preoperative endothelial cell count over 2000/ mm2. None of the patients had any anatomical anterior segment disease.

Dr Baikoff said that implantation of the lens is a very simple surgical procedure. It requires only the use of a routine cataract set with no special instruments apart from the lens-folding device.
Endothelial cell loss was about 5% but the cell count has remained stable in patients followed for up to one year. Some patients experienced halos but none of the patients stopped night driving.

Most patients did not complain about the loss of contrast sensitivity and most of those who had one eye implanted with the lens requested to also have the lens implanted in their other eye.

However, one patient who was dissatisfied with the result asked for the lens to be explanted, while another patient, a 75-year-old woman, had a poor visual outcome due to an incipient cataract. She has since had a good visual outcome following explantation of the lens and extraction of the cataract.
Dr Baikoff predicted that anterior chamber refractive lenses will become an increasingly attractive option to the ametropic patient and the refractive surgeon with the advent of new machines like the Artemis Ultra-Link and the Zeiss Humphrey OCT device.

The Artemis machine uses high frequency ultrasound to provide accurate measurements of the anterior segment diameter together with all the other biometric data of the anterior chamber.

The Zeiss Humphrey machine, which is currently just a prototype, uses optical coherence tomography to achieve the same thing in a 10-second examination which involves no contact with the eye.
“The era of anterior chamber lenses will improve very much and very quickly when all these devices come on the market,” Dr Baikoff said.

Simonetta Morselli MD
Verona, Italy
Email: morsell@tiscali.it

Jan Worst MD
Haren, The Netherlands
Email: jworst@omcnoord.nl

Camille Budo MD
Sint-Truiden, Belgium
Email: camille.budo@skynet.be

George Baikoff MD
Marseilles, France
Email: g.baik.opht@wanadoo.fr

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