November - December 2011 491 Cupped disc with normal intraocular pressure: The long road to avoid misdiagnosis Nikhil S Choudhari 1,2 , Aditya Neog 1,2 , Vimal Fudnawala 2 , Ronnie George 1 We present a series of six patients who had been receiving treatment for normal tension glaucoma (NTG; five patients) or primary open angle glaucoma (one patient). All of them were found to have optic neuropathy secondary to compression of the anterior visual pathway. Even though uncommon, compression of the anterior visual pathway is an important differential diagnosis of NTG. Diagnosis of NTG should be by exclusion. Here the possible causes of misdiagnosis are discussed. We present an approach to distinguish glaucomatous from nonglaucomatous optic neuropathy. The article also emphasizes how important it is for the clinicians to consider the total clinical picture, and not merely the optic disc morphology, to avoid the mismanagement of glaucoma, especially the NTG. Key words: Optic disc cupping, optic disc pallor, suprasellar tumor, glaucoma, neuroimaging Cite this article as: Choudhari NS, Neog A, Fudnawala V, George R. Cupped disc with normal intraocular pressure: The long road to avoid misdiagnosis. Indian J Ophthalmol 2011;59:491-7. Access this article online Quick Response Code: Website: www.ijo.in DOI: 10.4103/0301-4738.86320 PMID: *** Glaucomatous optic neuropathy is characterized by progressive loss of the nerve fiber layer resulting in diffuse loss or notching of the neuroretinal rim especially to the optic disc margin. [1] Other characteristic features of glaucomatous optic neuropathy include optic disc hemorrhage crossing the neuroretinal rim, intereye asymmetry of cupping in the absence of asymmetry of disc size, and parapapillary atrophy. [1] The current definition of glaucoma precludes intraocular pressure (IOP) as a defining feature. [2] One can diagnose glaucoma even when the IOP is “normal.” Unfortunately, in day-to-day practice, excessive cupping of the optic disc is considered to be pathognomonic of chronic glaucoma. One tends to diagnose “normal tension glaucoma” (NTG) if the IOP 1 Jadhavbhai Nathamal Singhvi Glaucoma Department, 2 Neuro- Ophthalmology Department, Medical Research Foundation, Sankara Nethralaya, 18, College Road, Chennai, India Correspondence to: Dr. Nikhil S Choudhari, Medical Research Foundation, Sankara Nethralaya, 18, College Road, Chennai – 600 006, India. E-mail: nkl164@gmail.com Manuscript received: 17.02.10; Revision accepted: 01.07.10 falls within the acceptable range oſten without investigating nonglaucomatous causes. In fact, in many cases, long-standing optic neuropathy can result in optic disc cupping. Causes of nonglaucomatous optic disc cupping include methanol poisoning, [3] arteritic anterior ischemic optic neuropathy, [4] and rarely chronic compressive lesions of the optic nerve. [5-8] In the present series, we report six patients, who were misdiagnosed and treated as having glaucoma, in whom bilateral optic disc cupping simulating glaucomatous optic neuropathy was a feature of compression of the anterior visual pathway. We discuss an approach to the not so rare clinical presentation of cupping of the optic nerve head associated with normal IOP to prevent similar occurrences in future. Case Report The cases are summarized in Table 1. Discussion The patients in this series ranged in age from 40 to 69 years. All of them had presented to their treating ophthalmologist with painless, gradually progressive vision loss. Except for a diffuse, dull headache at presentation to us in only one patient, none of them had any neurological symptoms. All were diagnosed to have glaucoma and were treated with IOP lowering measures. Three of them had undergone trabeculectomy. All, except the last, presented to us with progressive vision loss despite adequate treatment for glaucoma. Prue et al. [8] cited “a low index of suspicion” as a main culprit in the delayed diagnosis of chiasmal compression in 1973. This series illustrates why one should be extra-vigilant when diagnosing NTG even today. All these patients had signs that should have raised suspicion about the presumptive diagnosis of NTG [Table 2]. Notably, the morphology of the pupils and that of the optic nerve head excepting the vertical cup-to-disc ratio were not recorded in any of these patients. Prominent pallor that was more than loss of the neuroretinal rim, at least when we examined, was seen in all, except the fiſth patient. Misinterpretation of the visual fields is another significant factor for the misdiagnosis in these cases. For example, patchy visual field loss in the right eye of the second patient’s earliest visual field [Fig. 6B] could be mistaken for glaucomatous biarcuate visual field loss. On careful evaluation, the visual field defects in the earliest visual field respected the vertical meridian. Thinning of retinal nerve fiber layer (RNFL) on optical coherence tomogram might have been considered to represent glaucomatous optic neuropathy in the fourth patient [Fig. 10A]. Thinning of RNFL is the end result of any pathological process causing optic neuropathy and does not necessarily mean glaucoma. A comprehensive ophthalmic evaluation and appropriate interpretation of the clinical and/ or investigational findings could have saved the second, third, and fiſth patients from an erroneous diagnosis of glaucoma and glaucoma filtering surgeries. Moreover, neuroimaging at least when the visual loss was progressive despite achieving low IOP could have prevented further visual loss in them as well as in the first patient. Distinguishing glaucomatous from nonglaucomatous optic disc cupping on clinical examination is difficult. Generally, the optic disc in patients with intracranial compressive lesions Brief Communications