Comment on: An unusual presentation of nonarteritic ischemic optic neuropathy with subretinal fluid treated with intravitreal bevacizumab.

Abstract

Sir, It was with great interest we read the article “An unusual presentation of nonarteritic ischemic optic neuropathy (NAION) with subretinal fluid treated with intravitreal bevacizumab” by Dave and Pappuru.[1] We have noticed some points in the text and would like to put forth few queries which we feel were not addressed adequately in this article. Diabetic status of the patient has not been mentioned. It is known that diabetes mellitus, apart from hypertension, is a predisposing factor for the development of NAION and the characteristics of such patients differ from nondiabetic patients with NAION.[2] We agree that macular edema is an unusual finding in NAION even in fundus fluorescein angiography (FFA) studies as mentioned by the authors. Yet the authors have not mentioned FFA findings in the article. We believe FFA of the affected eye is essential in cases of atypical NAION with sub retinal fluid (SRF) to rule out inflammatory pathologies. Other eye's visual fields, fundus image, FFA, and optical coherence tomography would have been helpful for comparison and to rule out any other pathologies. Improvement in visual acuity cannot be contributed to intravitreal bevacizumab with certainty as vision is known to improve, in >40% cases, with the natural history of disease.[3] Authors have documented 20/200 best-corrected visual acuity in other eye post-NAION. Hayreh and Zimmerman have shown the difference in final visual outcomes in eyes of patients with bilateral sequential NAION.[4] Low final vision in one eye cannot be used as a predictor of poor prognosis when other eye develops NAION and should not be an indication for interventional treatment. Authors have documented an improvement in visual acuity but have not commented on the visual fields during follow-up. We found two reports of intravitreal bevacizumab being associated with the development of NAION in literature and we are mentioning one due to the restriction of a number of references.[5] It is postulated to be due to the transient raised IOP caused by the injection affecting the already compromised optic disc. Keeping this in mind and the fact that NAION recovers to some extent in its natural history, we feel that this therapy needs to be proved through proper randomized trials before being tried in NAION patients. Macular edema and subretinal fluid have also been described in literature and have been shown to resolve without use of any treatment.[2] We feel the presence of subretinal fluid or macular edema does not necessitate treatment in such cases. The authors, Dave et al. have mentioned in their reference number 11 that the article on “Macular star in Optic neuropathy” by Wang AG, Lui JH, Lin CL, and Yen MYwas published in “Am J Ophthalmol,” when in fact it was published in “Annals of ophthalmology” in 1995. The abstract mentions the last follow-up being at 6 months while text documents it as 3 months. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.