not relevant; this specific point is already the subject of numerous studies and reviews. The only thing that really matters is that it be done promptly and by expert physicians. Unfortunately, patients with retinal TIAs and permanent retinal ischemia often receive delayed care because of inappropriate referrals by eye care providers; it is important to recognize that patients with acute retinal ischemia are relatively uncommon in general ophthalmology, and that simple recommendations such as those suggested in my editorial are likely the best way to ensure that all such patients receive immediate appropriate care. These recommendations follow those from the National Stroke Association1 and the American Heart Association,2 which emphasize the need to immediately and aggressively evaluate and manage all patients with acute cerebral and ocular ischemia. Although the study by Lee and associates3 indeed did not include patients with isolated transient retinal ischemia, my editorial also commented on another study from Boston published in 2012,4 which showed that retinal arterial ischemia (both transient and permanent) carries the same overall poor vascular prognosis as cerebral ischemia. Not surprisingly in the Boston study, the probability of abnormal magnetic resonance imaging (MRI) was higher in permanent visual loss patients than in retinal TIA patients (33% vs 18%). However, patients with transient retinal ischemia and an abnormal MRI had a high risk of having a major etiology as the cause of retinal TIA and, therefore, had a worse prognosis. The practice of medicine is difficult, and access to care is becoming more challenging for many patients, who often choose to present to local walk-in optometry clinics in shopping centers or to urgent care centers where non-specialists have to make rapid triage decisions and often have difficulty obtaining urgent outpatient tests and consultations. Additionally, most academic ophthalmology departments are ‘‘opting out’’ of the systematic measurement of vital signs on their ophthalmology patients. As specialists with expertise in vascular diseases, it is our duty to facilitate emergent evaluations of patients with presumed retinal TIAs or permanent retinal ischemia. The details of how such evaluations should be performed vary greatly depending on patient characteristics and local resources, and I am pleased to see that Drs Brown and Vasudevan already have a strategy in place to handle such patients. VALE´RIE BIOUSSE

Atlanta, Georgia CONFLICT OF INTEREST DISCLOSURES: SEE THE ORIGINAL article for any disclosures of the author.

REFERENCES

1. Easton JD, Saver JL, Albers GW, et al. Definition and evaluation of transient ischemic attack: a scientific statement for healthcare professionals from the American Heart Association/American

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Stroke Association Stroke Council; Council on Cardiovascular Surgery and Anesthesia; Council on Cardiovascular Radiology and Intervention; Council on Cardiovascular Nursing; and the Interdisciplinary Council on Peripheral Vascular Disease. The American Academy of Neurology affirms the value of this statement as an educational tool for neurologists. Stroke 2009;40(6): 2276–2293. 2. Johnston SC, Albers GW, Gorelick PB, et al. National Stroke Association recommendations for systems of care for transient ischemic attack. Ann Neurol 2011;69(5):872–877. 3. Lee J, Kim SW, Lee SC, Kwon OW, Kim YD, Byeon SH. Cooccurrence of acute retinal artery occlusion and acute ischemic stroke: diffusion-weighted magnetic resonance imaging study. Am J Ophthalmol 2014;157(6):1231–1238. 4. Helenius J, Arsava EM, Goldstein JN, et al. Concurrent acute brain infarcts in patients with monocular visual loss. Ann Neurol 2012;72(2):286–293.

Factors Influencing Long-Term Regression After Posterior Chamber Phakic Intraocular Lens Implantation for Moderate to High Myopia EDITOR: WE HAVE READ WITH GREAT INTEREST THE ARTICLE BY

Kamiya and associates.1 The authors showed that eyes of older patients and eyes with longer axial length were more predisposed to have greater myopic regression after posterior chamber phakic intraocular lens (Visian ICL; STAAR Surgical) implantation. We are confident that the study was well designed, but we have the following comments from a statistical point of view. First, they analyzed the results from 60 eyes from 35 patients. In other words, 10 eyes from 10 patients and 50 eyes from 25 patients were selected for the analysis in this study. The stepwise multiple regression analysis and Spearman rank correlation analysis, which were used in this study, are meaningful only under the assumption of independence of the data. To collect data from 1 or both eyes of a subject in ophthalmic statistics has been a main argument in terms of the dependence of observations.2,3 The use of measurements from only 1 eye for studies involving eye-specific outcomes is recommended, especially when the correlation between eyes is strong.3 We recommend that the between-eye correlation in the subjects should be estimated and 1 eye from 35 patients should be used for the final statistical analysis. Second, the authors performed the Spearman rank correlation analysis, a nonparametric method, to assess the univariate relationship of myopic regression with other variables. When the variables are not normally distributed or the relationship between the variables is not linear, it may be more appropriate to use the Spearman rank correlation analysis. However, the multiple regression analysis, a parametric method, used in the same table can be feasible

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DECEMBER 2014

when the relationships between dependent variable and independent variables are linear and the dependent variable is normally distributed. Table 2 showed the results from the univariate and multivariate analyses with discrepant assumptions on the distribution of the same variables. Sixty eyes could be regarded as a sufficiently large number according to the central limit theory; it seems more appropriate to use the Pearson correlation coefficient, a parametric method, as a univariate version of the multiple regression analysis in Table 2.

correlation coefficient was used for statistical analysis, we obtained almost similar results that there were significant correlations of myopic regression with the preoperative axial length and patient age, and no significant correlation shown with other clinical factors. Accordingly, we believe that eyes of older patients and eyes with greater axial length showed greater long-term myopic shift after posterior chamber phakic intraocular lens implantation.

SHIN HAE PARK

AKIHITO IGARASHI

HAE RI YUM

HIDENAGA KOBASHI

YONG-GYU PARK

Kanagawa, Japan

KAZUTAKA KAMIYA KIMIYA SHIMIZU

Seoul, South Korea THE AUTHORS HAVE COMPLETED AND SUBMITTED THE ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. The authors indicate no funding support.

CONFLICT OF INTEREST DISCLOSURES: SEE THE ORIGINAL article for any disclosures of the authors.

REFERENCES REFERENCES

1. Kamiya K, Shimizu K, Igarashi A, Kobashi H. Factors influencing long-term regression after posterior chamber phakic intraocular lens implantation for moderate to high myopia. Am J Ophthalmol 2014;158(1):179–184. 2. Karakosta A, Vassilaki M, Plainis S, Elfadl NH, Tsilimbaris M, Moschandreas J. Choice of analytic approach for eye-specific outcomes: one eye or two? Am J Ophthalmol 2012;153(3): 571–579. 3. Armstrong RA. Statistical guidelines for the analysis of data obtained from one or both eyes. Ophthalmic Physiol Opt 2013; 33(1):7–14.

1. Kamiya K, Shimizu K, Igarashi A, Kobashi H. Factors influencing long-term regression after posterior chamber phakic intraocular lens implantation for moderate to high myopia. Am J Ophthalmol 2014;158(1):179–184. 2. Karakosta A, Vassilaki M, Plainis S, Elfadl NH, Tsilimbaris M, Moschandreas J. Choice of analytic approach for eye-specific outcomes: one eye or two? Am J Ophthalmol 2012;153(3):571–579. 3. Armstrong RA. Statistical guidelines for the analysis of data obtained from one or both eyes. Ophthalmic Physiol Opt 2013; 33(1):7–14.

Tattoo-Associated Uveitis EDITOR:

REPLY

WE WERE VERY INTERESTED TO READ THE RECENT ARTICLE WE APPRECIATE THE INSIGHTFUL COMMENTS OF DR PARK 1

and associates on our published article. We agree with their opinion that the use of measurements from only 1 eye for studies involving eye-specific outcomes is recommended for the statistical analysis because of inter-eye correlation.2,3 Otherwise, the model-based analysis such as mixed model is useful when both eyes from 1 patient are included. We examined 60 eyes of 35 consecutive patients undergoing posterior chamber phakic intraocular lens implantation in the current study, in accordance with many published studies on refractive surgery. However, even when we included 35 eyes of 35 patients, we obtained similar results that the explanatory variables relevant to the myopic regression were the preoperative axial length and patient age. Moreover, the normality of all data samples was first checked by the Kolmogorov-Smirnov test. Since the data did not fulfill the criteria for normal distribution, the Spearman correlation coefficient was used to assess the univariate relationship of myopic regression with other variables in the present study. Even when the Pearson VOL. 158, NO. 6

by Ostheimer and associates,1 describing a series of 7 patients with tattoo-associated uveitis. The authors imply that this represents a distinct clinical entity with temporally associated skin inflammation and uveitis, triggered by recent tattooing. Notably, the patients in this series had no evidence of systemic sarcoidosis or infective causes of uveitis. As originally detailed by Rorsman and associates,2 the proposed underlying pathophysiology of this condition is a specific delayed type of hypersensitivity reaction to particular tattoo pigments, which contain metallic compounds such as cobalt, nickel, and iron. Identification of the specific tattoo pigments that trigger this condition in susceptible individuals would therefore be useful and could lead to elucidation of therapeutic targets. In our practice, we have managed 3 patients with tattooassociated uveitis in the last year. One of these patients is a 21-year-old tattoo artist, who presented with bilateral anterior uveitis and skin inflammation, centered on black pigment in extensive whole body tattoos. He was otherwise in good health and did not have any features of systemic

CORRESPONDENCE

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