PRESBYOPIA INLAYS

Intracorneal inlays implanted in the non-dominant eye, including bifocal refractive and pinhole aperture designs, are effective for treating presbyopia, presenters at an ESCRS symposium told the refractive surgery subspecialty day of the American Academy of Ophthalmology annual meeting. Though some are still in the early stages of development, they are generally welltolerated and stable refractively, and longer follow-up is required to demonstrate their long-term viability.

In a 12-month study of the second generation of the ICOLENS (Neoptics, Hunenberg, Switzerland), 60 per cent of patients gained two or more lines of near visual acuity and 34 per cent gained three or more lines, said Thomas Kohnen FEBO, Goethe University, Frankfurt, Germany. The 3.0mm ICOLENS is composed of a copolymer with hydrogel properties. A 0.15mm hole in the centre facilitates nutrient flow, and the lens is curved to minimise changes in corneal curvature. A central distance zone is surrounded by a positive refractive zone for near. It is implanted about 300 microns deep into a tunnel cut by femtosecond laser using a special preloaded injector.

Of the 52 patients implanted in 2011, 47 retained the lens for 12 months, Prof Kohnen noted. Of those, all were generally satisfied, though 70 per cent still used reading glasses “sometimes†and 24 per cent “oftenâ€. Before surgery, all used reading glasses full-time, with uncorrected near VA of 20/50 or worse. However, 30 per cent lost one or two lines of uncorrected distance acuity. Even so, 86 per cent reported their distance vision was not impaired, with the remaining 14 per cent finding it impaired “sometimesâ€, Prof Kohnen reported. Mean change in corneal curvature was +0.20 +/-0.78 D. There were no complications and no reports of pain or discomfort, though six patients reported mild or intermittent glare not serious enough to interfere with driving.

These results were an improvement over the first design, which Prof Kohnen implanted in four patients in 2010. Of those, one saw uncorrected near vision improve from 20/50 before surgery to 20/25 at 24 months, while uncorrected distance dropped from 20/20 to 20/32. The other three patients saw large decreases in distance vision with little improvement in near. Their lenses were explanted, restoring vision and demonstrating the reversibility of the procedure. Based on this experience, the lens edge was thinned, from 20 microns to 15, and its curvature changed based on observed anterior corneal changes, resulting in a more-predictable effect.

ICOLENS patients recover quickly without lost work time and no corneal complications have been observed, Prof Kohnen said. However, the technical procedure has a learning curve, and patients sometimes do not achieve optimal results despite excellent surgical outcome and lens selection. Further refinements are in progress, he said.

Ioannis Pallikaris MD, PhD, University of Crete, Greece, also reported good results with another hydrogel intracorneal implant for presbyopia, the Flexivue Micro-Lens (Presbia). Also implanted in a pocket created by a femtosecond laser in the non-dominant eye, the 3.0mm lens has a peripheral add of +1.25 to +3.0 D. It improved uncorrected near vision from a mean of 20/100 to 20/25, with uncorrected distance declining from 20/20 to 20/40 in the operated eye. However, binocular distance vision was unaffected in the 40 patients studied, Dr Pallikaris said.

After surgery 92 per cent reported no need for reading glasses, and no intra- or postoperative complications were seen, Dr Pallikaris said. Intracorneal lenses are safe and effective for treating presbyopia in patients aged 45 to 65, he concluded. Gunther Grabner MD, Salzburg, Austria, reported excellent long-term results with the KAMRA pinhole inlay (AcuFocus, California, US). The 3.8mm-diameter inlay has a 1.6mm aperture in the centre. Dr Grabner began implanting an early model six years ago. Since then, thickness has been reduced to 5.0 microns from the original 25, it is now made of polyvinylidene fluoride instead of Dacron or polymide, and it now contains 8,400 pores of variable size distributed pseudo-randomly rather than uniformly as in the earliest versions.

At 36 months, 32 emmetropic patients gained a mean of 4.6 Jaeger lines near vision, achieving J2 from J7-J8 preoperatively, as well as 20/25 intermediate vision from 20/40. Distance vision in the operated eye fell from a mean of 20/16 to 20/20. “What I like most about this technique is that basically they lose very little distance visual acuity,†Dr Grabner said. In addition, reading acuity and speed increase. All patients reported they could drive at night without glasses, and would have the surgery again, he added. For 17 cases that have reached 60 months follow-up, mean near vision has remained stable at J2, while mean near vision in the non-implanted eye has dropped from J8 to J9.

Complications include one case of epithelial ingrowth requiring two flap lifts, and two decentred implants that were re-centred at seven months. One implant inserted at a shallow 140 microns was removed due to a hyperopic shift. “It seems to be stable, it doesn’t show inflammation or changes over time,†Dr Grabner said. Dr Grabner has implanted the KAMRA in post-LASIK, patients, ametropes up to -5.0 D and +3.0 D, as well as patients with monofocal IOLs. “This will be a very nice group to target.†In 20 pseudophakic cases, near vision improved from J6 to J2 over one year, he noted. Dr Grabner pointed out that with up to 60 months follow-up and more than 18,000 implants, including 12 ophthalmologists and four optometrist, the KAMRA is stable and well tolerated causing minimal loss of distance visual acuity, and allows for complete ocular exam and treatment postoperatively.