APR 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

Issue link: https://digital.eyeworld.org/i/119916

Contents of this Issue


Page 68 of 82

April 2013 Review continued from page 65 postoperative cataract patients and determine their source of dissatisfaction. In particular, the retrospective design allowed for a fairly large sample size despite the fact that a significant number of patients were excluded for criteria such as dry eye, posterior capsular opacification, and macular pathology. Unfortunately, retrospective cohorts inherently create biases such as selection bias, self-selection bias, and sampling bias. Selection bias affects studies that employ surveys because the data is inherently skewed toward a non-random population of patients who elect to participate in the survey. This study does not give any information on how many patients were eligible and how many of those decided to enroll in the study. Similarly, self-selection bias may arise in a survey-based study when certain characteristics of patients cause them to enroll in a nonrandom manner. Patients who are willing to be involved in such studies have certain personality traits that can differentiate them from the general population. Sampling bias occurs in highly controlled patient populations, as seen in studies like this, where stringent exclusion criteria make it difficult to extrapolate results to the general population. We commend the authors' efforts to eliminate confounding variables in an attempt to determine which complaints are attributed solely to the pseudophakic state. The strict exclusion criteria, however, reduced the cohort from 2,953 patients down to only 70 patients who were successfully enrolled, eliminating nearly 98% of the initial group. Given this exceptionally high rate of exclusion, it would be interesting to know which patients were excluded for each criterion so that we can gain a better understanding of how we can apply the results of this paper to our patients in a clinical setting. Finally, the order in which the questionnaires were given, which was not discussed in the paper, may have affected patient responses. The PDQ was designed to enumerate complaints and calculate awareness about dysphotopsias. Therefore, answering a question regarding overall satisfaction before or after completing the PDQ may yield different responses. For instance, patients who initially feel satisfied about their vision may change their opinion after realizing they have dysphotopsias from answering the questions in the PDQ. Conversely, if the overall satisfaction question is answered prior to completing the PDQ, a patient may report a higher satisfaction score. We praise the authors for taking on a challenging and ubiquitous topic that certainly has significant relevance to ophthalmologists worldwide. Studies such as this may help us understand how to increase patient satisfaction, possibly by improving IOL designs and surgical approaches to decrease positive dysphotopsias. EW Contact information Weikert: mweikert@bcm.edu Measure continued from page 64 your A constants for more accurate refractive outcomes. Specialized IOL calculation software programs can track these outcomes for you and apply newer formulas to provide more accurate outcomes. The future of IOL calculation formulas is bright with newer methods of modeling the eye for better effective lens position predictions coming in the next two to three years. EW References 1. Knox Cartwright NE, Johnston RL, Jaycock PD, Tole DM, Sparrow JM. The Cataract National Dataset electronic multicentre audit of 55,567 operations: when should IOLMaster biometric measurements be rechecked? Eye (London, England) 2010; 24(5):894900. 2. Wang L, Shirayama M, Ma XJ, Kohnen T, Koch DD. Optimizing intraocular lens power calculations in eyes with axial lengths above 25.0 mm. J Cataract Refract Surg 2011;37(11):2018-2027. 3. Gavin EA, Hammond, CJ. Intraocular lens power calculation in short eyes. Eye (London, England) 2008; 22(7):935-938. 4. MacLaren RE, Natkunarajah M, Riaz Y, Bourne RRA, Restori M, Allan, BDS. Biometry and formula accuracy with intraocular lenses used for cataract surgery in extreme hyperopia. Am J Ophthalmol 2007;143(6):920-931. 5. Fotedar R, Wang JJ, Burlutsky G, Morgan IG, Rose K, Wong TY, Mitchell P. Distribution of axial length and ocular biometry measured using partial coherence laser interferometry (IOL Master) in an older white population. Ophthalmol 2010; 117(3):417423. Editors' note: Drs. Banta and Gardiner have no financial interests related to this article. Dr. Vann has financial interests with Alcon (Fort Worth, Texas). Contact information Banta: JBanta@med.miami.edu Gardiner: Matthew_Gardiner@meei.harvard.edu Vann: Robin.Vann@duke.edu

Articles in this issue

Links on this page

Archives of this issue

view archives of Eyeworld - APR 2013