LAUSR

Dear Editor-in-Chief, I read with great interest the article by Razek et al. in which they illustrate the results of their study investigating the utility of diffusion tensor imaging (DTI) of the optic disc in differentiating between patients with idiopathic intracranial hypertension (IIH) and control individuals [1]. The authors reported devastating results supporting the possible value of DTI parameters of the optic disc in the clinical evaluation of IIH including significant differences between patients (IIH) and controls; patients with early papilledema and advanced papilledema; patients with early visual field defects; and patients with advanced visual field defects for both parameters of DTI (FA and MD). In their study conclusion, the authors emphasized that DTI parameters of the optic disc are noninvasive reliable imaging tools that may help in the diagnosis of IIH, and they remarked that it was well correlated with the degree of papilledema and visual field defects. First, I would like to express my sincere appreciation for conducting this valuable study. However, I would like to make some observations to better understand of the study results and offer some crucial suggestions to be kept inmind in future-related studies. First, I would like to mention a set of clinical challenges during the follow-up course of these patients which I think may help underscore the importance of the study results. IIH can be defined as a condition with raised intracranial pressure (ICP) in the absence of identifiable cause, which may cause significant inconvenience to the patients and has the major comorbidity of visual loss with 5% to 10% of patients progressing to blindness [2]. Thus, although rare, IIH is accepted as an important disease that requires careful, long-term follow-up visits [3]. Elevated lumbar puncture (LP) opening pressure constitutes one of the criteria for diagnosis [4]. However, considering the technical difficulties, measurement of LP is not routinely performed following the diagnostic procedure. During the follow-up course of the patients, ophthalmic examinations are vital for the detection of early visual deterioration and management of the treatment changes as well. Remarkably, among these clues, visual field testing is themost sensitive and critical method for monitoring the visual deteriorations during the course of the disease, which the authors noted [1, 2]. However, we know the standard automated perimetry to be inherently subjective and prone to patient error [5]. Additionally, a possible visual field defect found during perimetry visual field testing cannot provide a clear conclusion about the occurrence time of this defect if no basal visual field test exists for comparison (if it has occurred recently or a long time ago?). Hence, the results of the visual field examination may not provide a proper evaluation of the disease activity of IIH during the evaluation time. On the other hand, other clinical clues such as headache severity and papilledema degree may provide substantial data about the disease activity and help clinicians to guide treatment decisions. Of note, the severity of papilledemawas also shown to be positively correlated with LP opening pressure, which is a direct sign of disease activity in IIH [6]. Remarkably, in the study by Razek et al., DTI parameters of the optic disc were shown to be clearly correlated with both findings (visual field defect and papilledema)which are complementary, but also distinct in terms of themechanisms and clinical utility. Taken together, I think that this proposed tool of DTI of the optic disc may potentially constitute an excellent paraclinical marker in the near future andmay even replace ophthalmologic examinations performed during routine follow-up visits. However, these findings require confirmation in future studies including larger groups of patients. The authors also interpreted the value of differentiation between early and advanced papilledema given that this knowledge may benefit during patient selection for surgical intervention and prevent the development of secondary optic atrophy. In my opinion, based on this study method (even though the follow-up and prognosis of patients were not included), commenting on this conclusion would not be rational and may lead to false conclusions. * Halil Onder [email protected]