REFRACTIVE SURPRISES AFTER CATARACT SURGERY

Two types of  IOL designed specifically for supplementary implantation into the sulcus, the Rayner Sulcoflex® and the Humanoptics MS714, appear to provide a safe and effective alternative in the treatment of refractive surprises after cataract surgery, and can also provide a more easily reversible form of multifocal pseudophakia, said Michael Amon MD, Academic Teaching Hospital of St John, Vienna, Austria.

“Peer-reviewed studies show that both lenses are very biocompatible. They show that there is 100 per cent clearance of the IOL between the lens and the uveal tissue. There was also excellent rotational stability and excellent visual results and there were no serious intraoperative or postoperative complications,†Dr Amon said at the XXIX Congress of the ESCRS.

Dr Amon noted that the lenses offer a greater level of safety and predictability compared with standard IOLs implanted as add-on lenses in the capsular bag or sulcus. For example, there is no danger of interlenticular opacification because of their position in the sulcus, he said. Moreover, unlike biconvex conventional IOLs, their concave posterior surface does not press against the posterior chamber IOL, which can distort the shape of both lenses and cause a hyperopic defocus.

The two sulcus-fixated lenses both come in aspheric monofocal, multifocal, toric and multifocal toric versions. The Humanoptics lens is a three-piece lens with a silicone optic and PMMA haptics. The Rayner lens is a single-piece lens composed of hydrophilic acrylic. The materials of both lenses are very well tolerated within the uveal tissue in terms of foreign body giant cell reactions. Both lenses have large optics, 6.5mm for the Rayner and 7.0mm the Humanoptics lens. They therefore cover the whole of the primary lens, he pointed out.

Furthermore, both lenses also have round edges to reduce photic phenomena. The haptics of both lens types are 14mm and have an undulating design to insure centration and rotational stability, and an angulation designed to insure uveal and iris clearance and prevent the inflammatory reactions and pigment dispersion that can occur when conventional IOLs are implanted in the sulcus.

Studies demonstrate safety and efficacy

Dr Amon noted that in a study involving 92 eyes of patients with mean age of 53.4 years who underwent implantation of the Sulcoflex IOL, the mean postoperative uncorrected visual acuity was 0.92 at a mean follow-up of 42 months and all eyes were within 0.25 D of intended refraction.

Furthermore, there were no intraoperative complications and the procedure appeared to be only minimally traumatic. Intraocular pressure at final follow-up ranged from 11.0 mmHg to 22.0 mmHg and laser flare cell metre counts ranged from 5-30 photon counts/ms, which was less than after phacoemulsification during the primary IOL procedure. In addition there was no evidence of iris trauma, pigment dispersion or interlenticular opacification.

Moreover, in all cases of OCT, Scheimpflug imaging and ultrasound biomicroscopy showed positive distances between the supplementary IOL’s  anterior surface and the iris and between the posterior surface of the add-on lens and the anterior surface of the IOL in the capsular bag. Furthermore, IOL stability and rotation were also very good in the majority of cases although in three per cent of eyes there was a rotation of more than 10 degrees (J Cat Refract Surg 2010; 7:1090-1094).

Patients implanted with the diffractive multifocal version of the Humanoptics lens achieved very similar results in a study involving 73 eyes carried out by Georg Gerten MD and associates in Koln Germany, Dr Amon said. The patients in the study underwent implantation of both the primary IOL in the capsular bag and the diffractive multifocal version of the Humanoptics sulcus-fixated IOL in the same procedure.

At a follow-up of 18 months, the patients’ mean monocular uncorrected distance visual acuity was 0.10 logMAR, and their mean uncorrected near visual acuity was 0.16 logMAR. Furthermore there were no major complications, no interlenticular opacification, and no iris trauma. Some pigment dispersion occurred in five cases but it resolved in three months. ( J Cat Refract Surg 2009; 35: 2136-2143.

Surgery easy and reversible

Dr Amon said that implantation of the Sulcoflex and Humanoptics supplementary IOLs is a fairly simple procedure. Injectors are available for both lens type and they can also be implanted with forceps, he noted. He generally implants the lenses through a 2.75mm incision, although an injector for implantation through a 1.8mm incision is available for the Sulcoflex.

Furthermore, unlike IOL exchange, the ease of surgery and the quality of the results with supplementary IOLs are not affected by the changes that occur to the capsular bag during the first few months after primary IOL implantation. In addition, unlike LASIK, the results are reversible. The sulcus-fixated design also lends itself well to use in the growing eyes of paediatric patients, since the lenses can be easily exchanged, without resorting to capsular surgery.

Moreover, the supplementary IOL approach also offers surgeons and their patients a more reversible approach to pseudophakic multifocality, Dr Amon said. Multifocal versions of the lens are available in versions with no affect on the distance focus of the primary intracapsular IOL, he noted. Therefore, if the patient is unhappy with their multifocality, only the sulcus fixated lens has to be removed and no further surgery is necessary.

“I think that these supplementary IOLs are effective for enhancement of the surgical result in pseudophakic eyes or for primary duet implantation with conventional IOLs,†Dr Amon concluded.

contact Michael Amon – amon@augenchirurg.com