December 2015




Patient satisfaction

Assessing objective, subjective clinical outcomes

by Rich Daly EyeWorld Contributing Writer


New tools provide more options for measuring both objective and subjective clinical outcomes

Although subjective patient assessments of outcomes from refractive procedures remain the most important factor for surgeons, they also need to use objective measures to critically analyze outcomes from new technologies.

Jorge Ali, MD, PhD, professor and chairman of ophthalmology, Miguel Hernandez University, and scientific director, Vissum Corp., Alicante, Spain, primarily relies on best corrected visual acuity (BCVA) and best uncorrected visual acuity, followed by contrast sensitivity function to measure visual function postop. Patient satisfaction is also analyzed by a short evaluation test.

Similarly, Michael Lawless, MD, clinical associate professor, University of Sydney, and ophthalmic surgeon, Vision Eye Institute, Sydney, Australia, uses Snellen acuity in routine cases, and in complicated cases he uses every subjective and objective test available to tease out subtleties in visual function and performance. That way I get to truly understand the worth of new technologies and dont have to rely entirely on whats published by others, Dr. Lawless said.

Subjective assessment

The subjective success in patient satisfaction is a critical factor in surgeons clinical outcome measurements. Dr. Ali requests anonymous patient feedback postop, provides a 10-question online survey, and accepts the in-person feedback opportunity preferred by older patients.

As part of his effort to get happy patients after surgical treatment of any kind of refractive failure, Alois K. Dexl, MD, MSc, associate professor of ophthalmology, Paracelsus Medical University, Salzburg, Austria, uses subjective measurements, such as questionnaires, defocus curves, near visual acuity, or reading function. Such steps are needed to understand potential problems or why patients might be unsatisfied with the postop achieved results. Subjective measurements will always be as necessary as objective measurements, Dr. Dexl said.

Such patient-reported outcomes are very important, said Guy M. Kezirian, MD, president, SurgiVision Consultants, Scottsdale, Ariz., and patient satisfactionregardless of the technologyis the true determinant of surgical success. The subjective nature of patient experience has led Dr. Kezirian and colleagues to design surveys with subjective metrics that compare before and after findings and are quantifiable. Purely subjective assessments are difficult to interpret, Dr. Kezirian said. It is far more helpful to know whether the patient relies on artificial tears to address dry eye symptoms than it is to ask, Do your eyes ever feel dry?

Multi-factor impacts

Contrast sensitivity, stray light measurements, disability glare, mesopic acuity, and simulated night driving also factor into outcomes.

Dr. Kezirian said that one of the unexpected epiphanies of previous clinical trials was that objective metrics may improve but the patients may not appreciate the difference. For instance, in the WaveLight (Alcon, Fort Worth, Texas) FDA trial for wavefront-guided LASIK, Dr. Kezirian found that 63% of patients achieved 20/12.5 uncorrected vision and a similar number improved at least one line of BCVA, but patients rated their vision before surgery with glasses to be about the same as after surgery despite the improved objective measurements.

The patients failure to appreciate the improvement does not imply the improvement is not experienced, Dr. Kezirian said. Rather, the patients failure to appreciate the improvement simply means they define a new normal and adjust to what they have. For this reason, subjective reports must always be captured alongside objective measurements. Both sets of findings are needed to draw valid conclusions. Specifically, Dr. Ali selectively measures professional drivers undergoing refractive or cataract surgery to ensure that they can meet professional and regulatory requirements. Stray light measurements are performed less frequently, while disability glare is more frequently performed because of strict requirements on drivers.

We need to advise the patients whether or not they are going to have a limitation when it comes to these types of exams, Dr. Ali said.

Dr. Lawless has found value in the McAlinden quality of vision questionnaire, which includes a Rasch-tested, linear-scaled, 30-item instrument on three scales providing a quality of vision (QoV) score in terms of symptom frequency, severity, and bothersomeness. It is suitable for measuring QoV in patients with all types of refractive correction, eye surgery, and eye disease that cause QoV problems, Dr. Lawless said. It gives great insight into visual performance and is a validated questionnaire so its as useful as an objective test.

Useful tools

To test contrast sensitivity, Dr. Lawless uses the CSV-1000 under photopic and mesopic conditions, uniocularly and binocularly. The tests are used with and without a glare source to truly test the visual system. Occasionally, Dr. Lawless also uses a night driving simulator, which is most useful in gauging reaction time and is only in part a measure of visual performance.

Two recent advances have greatly added to the ability of ophthalmologists to understand patient symptoms and to communicate with patients about what they are experiencing. The first is the use of light scatter to evaluate the quality of the visual image as it travels through the tear film, cornea, and lens to arrive at the retina. The second development is the integration of topography and ray tracing to separate the contribution of the cornea and tear film from the contribution of the lens to image quality. Among the commercially available technologies that measure those outcomesusing different approachesare the iTrace (Tracey Technologies, Houston), Visiometrics HD Analyzer (Terrassa, Spain), and the OPD III (Marco, Jacksonville, Fla.). The main application is in the evaluation of visual complaints in presbyopes and deciding on treatment options, Dr. Lawless said. Should the patient have LASIK to correct the refractive error or a lens replacement to address the dysfunctional lens syndrome, for example, a lens that will no longer accommodate? The images provided by such devices help in counseling patients, according to Dr. Lawless, because they allow the clinician to show the patient what is happening with his or her vision. For the first time, we have the ability to see what the patients see, Dr. Lawless said.

Dr. Ali uses wavefront analysis and aberrometry to measure patients clinical outcomes in every case that there is any complaint about quality of vision or photophenomena. With a wavefront sensor, KR-1W [Topcon Medical Systems, Oakland, N.J.], it is possible to separate the wavefront of the intraocular optics and the corneal surface and understand what exactly is happening to the patient, Dr. Ali said.

That approach is used for many multifocal lens recipients when newer models are used as an investigational deviceparticularly among patients reporting some type of disability or dissatisfaction related to the quality of their vision.

Dr. Lawless only uses wavefront analysis and aberrometry in complicated patients or second opinions. All of his LASIK cases are wavefront-optimized treatments, rather than wavefront-guided. Occasionally, Dr. Lawless measures and separates out whole eye aberrometry from corneal aberrometry, particularly in a post-LASIK setting where he is considering what type of intraocular lens will best minimize higher order aberrations.

New options

Dr. Lawless said light scatter can be measured by the Visiometrics HD Analyzer, which provides an objective scatter index, and the C-Quant (Oculus, Wetzlar, Germany), which has been reported in several studies to evaluate ocular forward light scatter.

Forward scatter is increasingly being recognized as visually disabling, but our understanding of its significance and our ability to measure it are lagging, Dr. Lawless said. Other new tools Dr. Ali has found useful in measuring such outcomes include the OSIRIS (CSO, Florence, Italy), which offers an aberrometry based not on Hartmann- Shack but on Foucault physics, which constitutes a new technology recently incorporated in the clinical study of ocular optics.

Dr. Dexls department has developed the Salzburg Reading Desk, which measures reading function under variable test circumstance, such as contrast and illumination.

While patients are able to read with an individual subjectively convenient reading distance, the device automatically calculates the corresponding reading acuityadjusted according to the reading distancereading speed and smallest print size, Dr. Dexl said.

Editors note: Dr. Dexl has financial interests with SRD Vision (Salzburg, Austria). Dr. Kezirian has financial interests with ALPHAEON (Irvine, Calif.). Drs. Ali and Lawless have no financial interests related to this article.

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