AcuFocus KAMRA, FDA: Yes, but…

The device has been in use since 2009 in various other countries. The 3.8 mm diameter, almost opaque device incorporating a 1.6 mm clear aperture centrally, relies on the simple optical expedient of the increased depth-of-focus afforded by small apertures.
The downsides of small apertures include light loss (blockage) and decreased image quality due to optical issues such as diffraction. The ‘iris’ has a light transmission of just 5.4% due largely to the numerous (8,400, 5.5-11 microns in diameter), barely perceptible pinholes perforating it in the interests of corneal nutrition. The device, which is made of polyvinylidene fluoride, is implanted at a depth of 180 microns and has a nominal radius of curvature of 7.5 mm which is somewhat steeper than the average cornea (7.8 mm). Normally, it is implanted into the non-dominant eye, is claimed not to diminish distance vision or binocularity.
Although it first received the CE Mark of approval in the EU in 2005, it was 2009 before the device became available internationally (first EU implantation was actually in 2010). It has also been available in Australia for more than three years. The number of countries it is now approved in is approaching 50 according to the company’s website and more than 20,000 devices have now been implanted world-wide.
2009 was also the year that FDA-sanctioned clinical trials commenced in the US. The submission resulting from that clinical trial series was reviewed by the FDA in June 2014. According to a 10 June 2014 report in Ophthalmology Times (Medscape published a similar article on 9 June), the FDA’s ophthalmic devices advisory panel determined, with significant reservations, that the benefits of AcuFocus’ Kamra inlay outweigh the risks for patients suffering ‘vision loss’ as a result of presbyopia. Clinical data on 508 patients in the US with the inlay implanted monocularly was the focus of the review that became a day-long hearing that ended with a split vote.
It was reported that amid concerns about safety and study methodology, the panel was largely convinced of the rovable inlay’s efficacy, voting 7 to 1 that there is ‘reasonable assurance’ that the product improves near vision in presbyopic patients who meet its indications.However, other results were not so clear-cut, e.g. the committee split down the middle, 4 to 4, on the question of reasonable assurance of safety, triggering a tie-breaking ‘no’ vote from committee chair, ophthalmologist Dr Neil Bressler (Wilmer Eye Institute, Baltimore).
Normally, the chair abstains from voting but in that case he cast a vote (no) to break the 4:4 deadlock. On a third question, whether the inlay’s benefits outweigh its risks, the vote was 4 yes, 3 no, and 1 abstention.
Dr Bressler is reported to have noted that while the current indications proposed are ‘for the improvent of near and intermediate vision in presbyopic patients’, the US trials involved implantation in ‘metropic’ patients.
As a result, several reviewing panel mbers advised the FDA to include the word ‘metropic’ in the product’s label if it was approved. It was estimated that of the 80 million US people who become presbyopic each year, only about 14%, or about 11 million people, are metropic presbyopes. An metropia-only indication would limit the potential US market for the device.
A quick inspection of some on-line reviews by KAMRA-equipped patients also reveals a mixed-bag of opinions. Those opinions are in keeping with FDA findings, e.g. 5.9% with a decrease in distance visual acuity of more than 2 lines at 3 months or later. Tellingly, but perhaps not surprisingly, outcomes were found to be better when a ftosecond laser was used to create the intracorneal pocket.
Significant IOP increases were also reported in 3.3% of cases.