Corneal inlay

Addressing delegates at the XXIX Congress of the ESCRS, Minoru Tomita MD, PhD, executive director of the Shinagawa LASIK Centre, Tokyo, Japan, said that the Kamra inlay (AcuFocus Inc.) provides excellent near and intermediate vision for patients without compromising their distance vision. “The initial results are very encouraging, although care must be taken when deciding the pocket depth in relation to the previous LASIK flap. On average, our patients gained six lines of uncorrected near visual acuity at 30cm with no changes in their uncorrected distance vision. Patient feedback was also very positive, with 95 per cent of the patients reporting that they were satisfied with their vision without reading glasses and 96 per cent of patients saying that their dependence on reading glasses had decreased,†he said.

The key to the performance of the inlay lies in the central aperture of 1.6mm aperture, which increases the depth of field and enables the patient to achieve improved vision for near and intermediate distance with a minimal effect on distance vision.

In Dr Tomita’s study, 741 post-LASIK presbyopes were implanted with the Kamra inlay in their non-dominant eye between November 2010 and August 2011.

The surgical procedure is very straightforward, said Dr Tomita. First, a corneal pocket was created at a depth of 200 to 250 microns below the LASIK interface using the FEMTO LDV Crystal Line femtosecond laser (Ziemer Ophthalmic Systems). The Kamra inlay was then inserted into the corneal pocket.

In almost one-fifth of cases, the prior LASIK flap was lifted and a laser touch-up of SE +0.52±0.60 D was performed to achieve postoperative plano refraction. Inclusion criteria included patients aged between 40 and 65 with a corrected distance visual acuity in both eyes better than 20/25 and uncorrected near visual acuity in the implanted eye of J-3 or worse. Patients needed to be at least one month post-LASIK surgery, with a corneal thickness greater than 450 microns, regular topography, endothelial cell density of at least 2,000 cells/mm2 and no severe dry eye, or ocular or corneal disease or immune system disorders.

Looking at the visual acuity results at three months postoperatively, Dr Tomita said there was no change in the mean uncorrected distance visual acuity, which remained at 20/16. The mean uncorrected near visual acuity at 30cm improved six lines from preoperative J-11 to J-3.

In terms of uncorrected distance visual acuity, 84 per cent of patients achieved 20/20 or better at three months. For uncorrected near visual acuity at 30cm, 31 per cent of patients achieved J-1, 42 per cent achieved J-2 and 78 per cent achieved J-3 or better.

Subjective patient satisfaction was also very high, said Dr Tomita. Over 95 per cent of the patients reported being either satisfied (10 per cent) or highly satisfied (85 per cent) with their visual acuity, while 96 per cent reported a decrease in their dependence on reading glasses since having the implant.

In a separate presentation, John Vukich MD discussed the two-year results from the United States FDA clinical trial of the Kamra inlay for the correction of presbyopia in emmetropes. He reported that the prospective, non-randomised study enrolled 507 patients at 24 sites worldwide, with the data from 99 patients available for inclusion at the two-year mark. The mean uncorrected visual acuity was J-3 for near, with an average 3.5 lines gain from baseline, said Dr Vukich.

“There was a trend that we have observed from one year to around 18 months postoperatively showing a continued improvement in their ETDRS reading score over that period,†said Dr Vukich.

Uncorrected intermediate vision showed a similar trend with a mean improvement to 20/25. For uncorrected distance vision, Dr Vukich said that there was an initial small drop in visual acuity followed by stabilisation to a mean of 20/20 at two years. He surmised that part of this drop might be due to the slight induction of astigmatism related to the creation of the corneal pocket for the inlay.

The best-corrected distance visual acuity remained high with an average of 20/16 for these patients. The binocular uncorrected vision (UDVA) was unchanged from preoperative to 24 months postoperatively (20/16), and the binocular photopic and mesopic contrast sensitivity was all recorded as within normal limits, he added.

Dr Tomita noted that the Kamra inlay is currently under investigational trials in the US but is available for use in Japan, and received the European CE mark in 2005.