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Presbyopia Challenge | May/Jun '14

Striving for Better Endpoints

In our last Presbyopia Challenge column, Jeremy Kieval, MD, highlighted the challenge of measuring success in the correction of presbyopia. How exactly do our clinical tests correlate with visual function in patients’ lives? Does good vision on a near card equal a happy patient? How do the working distance, lighting, contrast, and quality of a near target translate into functional vision?

While these questions are interesting to think about and to discuss in Presbyopia Challenge, the FDA faces the very real and daunting task of taking these and other clinical measurements and determining if an IOL produces the outcomes claimed, thus gaining FDA approval. To this end, the FDA and the American Academy of Ophthalmology (AAO) met in the first-ever public workshop: FDA/AAO Workshop on Developing Novel Endpoints for Premium Intraocular Lenses, in Silver Spring, MD, on March 28, 2014. At this collaborative meeting, members of the FDA, practicing ophthalmologists, and representatives from industry met and discussed the issues and challenges that we face in evaluating new presbyopia IOL technology.

As an introduction, the limitations of the existing endpoints for measuring success after cataract surgery and IOL implantation—both in terms of safety and efficacy—were discussed. Most traditional outcome measures are still relevant to modern cataract surgery, but many have limited benefit in assessing the success of the presbyopia-correcting component of these IOLs. BCVA, vitreous loss rates, and endophthalmitis rates are important, but they tell us nothing about the patient’s uncorrected vision and ability to function without glasses. Other traditional outcome measures may need reinterpretation. Reoperation rates are important to quantify, but reoperation for purposes of refractive enhancements is, by nature, very different than reoperation for other indications. Traditionally, reoperation is considered only when there is loss of BCVA (a measure of safety); conversely, reoperation after presbyopic IOL implantation for refractive purposes is considered only when BCVA is good. New outcome measures, such as uncorrected near vision, spectacle independence, and depth of focus, need to be described and standardized.

During the FDA/AAO workshop, an emphasis was made on the relevance and importance of patient-reported outcome (PRO) measures. The limitation of current PRO instruments, the process of developing validated PRO instruments, and the subtleties of how PRO data are captured were discussed. Next-generation presbyopia-correcting IOLs leverage a range of mechanisms (eg, multifocality, extended depth of focus, and accommodation) to improve uncorrected intermediate and near function. Different IOLs attempt to achieve different goals and balance side effects differently, eg, better near vision with some night vision symptoms versus improved intermediate vision with less near vision and fewer night vision symptoms. Because different IOLs have different goals and targets, objective outcomes—such as mean uncorrected near vision at 16”—at best do not tell the whole story and at worst may be misleading. Other considerations, such as the potential to mix and match, make outcomes assessment even more complex. Thus, the development of validated PROs, where patients can tell us if they are able to achieve the outcomes they expected, is key.

Therefore, regardless of the mechanism and objective performance of an IOL, patient satisfaction is a crucial endpoint. As we work toward the holy grail of presbyopic IOLs that can provide great vision at all distances with no compromises or visual side effects, we need a combination of objective outcome measures and validated PRO instruments to guide us as we evaluate future presbyopia-correcting IOL options. With the proper labeling information, surgeons can accurately assess the expected functional performance of available presbyopia-correcting IOLs. Only with this proper information can we create the appropriate level of enthusiasm while balancing expectations so that our patients can consistently achieve the level and quality of spectacle independence that they expect.

Daniel H. Chang, MD

Daniel H. Chang, MD, is in private practice at Empire Eye and Laser Center in Bakersfield, California. Dr.Chang is a consultant to Abbot Medical Optics. He may be reached at (661) 325-3937; dchang@empireeyeandlaser.com

May/Jun '14