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Simple tests still have a place in measuring IOL surgery outcomes
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New IOLs that allow functional vision at more than one distance continue to be developed. In general, we and our patients are first interested in the ability of an IOL to provide good best spectacle corrected visual acuity at distance with high contrast sensitivity at photopic and mesopic light levels and minimal unwanted visual images and negative or positive dysphotopsia.
The U.S. Food and Drug Administration approval process for such standard single-focus spherical and aspheric IOLs is well established, with hundreds of models approved and on the market worldwide. Still, we constantly debate whether asphericity really enhances performance in everyday life, as well as the impact of IOL design and material on the incidence and prevalence of negative or positive dysphotopsia and unwanted visual symptoms such as glare, halo and starburst. Other factors, such as incidence of posterior capsular opacification at 1 and 3 years, centration, absence of tilt, rotational stability (especially in toric IOLs) and material clarity over time, among many other minor points, are also important. While it is necessary to have objective outcomes to measure, patient-reported outcomes and subjective level of satisfaction become increasingly important every year, to both the clinician and the regulator. Finally, comparative efficacy and cost come to bear as well.
The “triple aim” goals of the Affordable Care Act are going to affect how the FDA and third-party payers, including the Centers for Medicare and Medicaid Services, look at products, whether we like it or not. The goals, simplistically stated, are a good objective outcome, a highly satisfied patient and a low/fair cost (good value). Defining each of these parameters, even for so-called standard cataract surgery with an FDA-approved monofocal IOL, presents significant challenges. If the patient is 20/20 at distance without correction, has no complications or unwanted visual symptoms, but is extremely unhappy with the way he or she was treated by the surgeon or office staff, in the modern world this is not considered a good outcome. The era of the “great surgeon with the extremely bad bedside manner” may be on its way toward extinction.
In addition, if the cost of the procedure is too high, even in the face of a great outcome and a happy patient, another group of patient and society advocates or third-party payer actuaries will relegate the case to the bad outcome bucket, especially if the government or any third party is paying the bill.
Now add multifocality, bifocal or even trifocal in nature, accommodation, extended depth of focus or perhaps a combination of the three, and the complexity becomes overwhelming. How does the FDA evaluate and approve these increasingly complex optical devices that we want to implant into our patients’ eyes? How do we compare one lens with another, both during scientific discourse and also during the informed consent process, one on one with each individual patient?
It is definitely not a simple world we confront every day as a dedicated ophthalmic surgeon attempting to do one’s duty to each individual patient and society as a whole. The FDA/AAO Workshop on Developing Novel Endpoints for Premium Intraocular Lenses convened March 28 in Silver Spring, Md., with the goal to reach consensus on some of these thorny issues. No report has been published to date, but most of my friends in attendance left with as many questions as answers.
It appears a new class of IOLs defined as extended depth of focus (EDOF) will be added to the current monofocal, multifocal and accommodating IOL categories.
The barrier to approval for an accommodating IOL currently stands at 1 D, and some experts have suggested a lower barrier, just 0.5 D, for EDOF IOLs. Wearing my clinician’s hat, I consider 0.5 D of increased depth of focus enough to improve near vision in a pseudophakic patient one line. While a one-line improvement is meaningful, many, if not most, of the classic prospective randomized clinical trials such as the ETDRS and the like found a lot of noise at the one-line improvement level and found the two-line improvement outcome a more meaningful parameter. That would put EDOF IOL analysis at 1 D, like accommodating IOLs. Of course, there is every reason to measure both, but ultimately one will be chosen as a primary outcome variable for approval.
As I analyze my own outcomes, I continue to find fairly simple outcome measures very helpful in comparing one multifocal, accommodating or EDOF lens to another. These include best distance spectacle corrected visual acuity, uncorrected vision at 80 cm and 40 cm with best distance spectacle correction in place, the amount of add required for best vision at 80 cm and 40 cm with best distance spectacle correction, and the depth of focus curve using a 20/30 or 20/40 target. These tests can all be done by any clinician and do not require any sophisticated technology. With a reasonable number of patients, meaningful outcome differences that are statistically and clinically significant are generated. Add to this photopic and mesopic contrast sensitivity, and a questionnaire regarding unwanted visual images and dysphotopsias and their severity, and we are well on our way.
I still like the simple patient-reported outcomes of: “Are you happy you had the surgery?” “Would you do it again?” and “Would you recommend it to your friends?” For comparative efficacy at near, reading speed with a standardized test in the patient’s own language in photopic and mesopic lighting is extremely valuable.
I remain unconvinced that any of the sophisticated “machines” or longer questionnaires give us more information than can be obtained using these simple tests. I especially like that these tests are within the capability of every ophthalmologist and optometrist and do not require the acquisition of expensive equipment.
No doubt, obtaining an accurate refraction or depth of focus curve in itself is no small challenge, and significant training and standardization are required to get reliable and meaningful data even with these simple tests. Still, I like the idea of keeping it simple and using tests that any eye doctor can replicate with their own patients to see if their individual outcomes are similar to those reported by the companies and their colleagues.