Square-edged IOL tackles PCO problems

Dermot McGrath in Paris

THE ACR6D SE (Cornéal), an intraocular lens with square-edge design, shows promising results for the effective control of cell proliferation on the posterior capsule, according to a French ophthalmologist.
Reporting to the annual meeting of the French Implant and Refractive Surgery Association (SAFIR), Michaël Assouline MD reported that the ACR6D SE incorporated several design innovations to control cell proliferation leading to problems of posterior capsular opacification (PCO).

"This IOL is designed with a square edge all around the optic, even at the junction with the haptics. It also comprises haptics with a posterior angle of 10 degrees to create a physical barrier to posterior migration of endothelial cells," he said.

In a retrospective study, 102 patients at two Paris clinics were implanted with ACR6D lenses over a period of two years, all by the same surgeon. In 54 cases, another IOL was implanted in the contralateral eye. Hydrophilic or hydrophobic acrylic intraocular lenses were used.

The mean age of the patients was 76, ranging from 49 to 98 years. Some 52 cases presented a potential preoperative limitation of their vision, and six patients had more than two concomitant diseases. These 52 patients included 15 cases of corneal disease, 23 cases of retinal disease and 20 cases of optic nerve disease.

The mean preoperative visual acuity was Parinaud 3.17 ± 1.82 in the ACR6D SE group and Parinaud 3.52 ± 2.53 in the control group. All procedures were performed under topical anaesthesia via a clear corneal approach with a direct incision of 3.2 mm, placed temporally, or on the most arched meridian in the case of preoperative corneal astigmatism greater than 1.25 D.

Medium pressure (5 to 25 mm Hg) posterior and high pressure (160 mm Hg) anterior capsular polishing was performed in every case. The incision was extended to 3.5 or 3.8 mm for insertion of the ACR6D SE.
Incisions were not sutured, according to Dr Assouline. "We prefer to inject the ACR6D to avoid contaminating the surface of the implant in contact with the conjunctiva," he said. Capsulorhexis was intact in every case.

Intraoperatively, the IOL was placed in the bag in 101 cases, and in a capsulociliary support in one case. No case of IOL decentration was observed during follow-up, noted Dr Assouline.

The mean visual acuity in the most recent follow-up was Parinaud 8.03 ± 2.75 in the ACR6D SE group and Parinaud 7.59 ± 2.85 in the control group. The mean gain was 4.89 ± 2.82 lines versus 4.26 ± 3.12 lines in the control group. The proportion of eyes achieving a final corrected visual acuity greater than or equal to 5/10, 8/10 and 10/10 was 89%, 68% and 37% in the ACR6D SE group, versus 86%, 54% and 29% in the control group, respectively. The IOL also displayed good refractive stability.

Dr Assouline reported that one case of eccentric capsulorhexis was observed in each group. Furthermore, three cases of haptic compression were observed in 102 cases versus one in 54 in the control group. No case of calcification was observed. Fusion of the anterior capsule with the posterior capsule was observed in two out of 102 cases for ACR6D SE versus 10 in 54 for the control group.

"This is related to the shape of the intraocular lens, which maintains the anterior capsule away from the optic, thereby limiting fusion with the posterior capsule," said Dr Assouline.

The formation of fibrosis covering less than 50% of the surface was also observed in one case. Ten cases developed grade 1 (nonrefringent unicellular layer) cell proliferation (PCO) covering between 20% and 50% of the surface. In six cases, grade 1 cell migration exceeded 50% of the zone of the central 6 mm or presented a refringent appearance (grade 2) interfering with vision. The overall YAG capsulotomy rate was 2.9% in the ACR6D SE recipients. In the group of patients with an implant in the contralateral eye, the mean YAG capsulotomy rate was 9.3%.

Dr Assouline commented that the study of retro-illumination films clearly showed that the posterior angulation of the haptics and the pressure exerted on the posterior capsule by square edges of the optic constituted an effective barrier to posterior migration of cells.

"Posterior capsule opacification and capsulotomy rates observed in this consecutive series were the best that we have observed to date with a hydrophilic material, including in comparison with other square-edge implants," said Dr Assouline. He noted that improvement of the design of hydrophilic acrylic implants appears to maintain the advantages of this type of material while effectively limiting the problems of posterior cell migration.

"This compromise appears to be preferable to that imposed by progressive fibrous metaplasia of the cells in contact with silicone, a source of contraction and capsular fusion, eccentric capsulorhexis and decreased transparency of the bag," concluded Dr Assouline.

"These data also suggest that the design of the implant is possibly more important than the material, as illustrated by the high capsulotomy rates observed with non-angulated hydrophobic implants."

Michaël Assouline, MD,
Fondation Ophtalmologique A de Rothschild, Paris, France
assouline1@aol.com

Top