Chiasmal compression misdiagnosed as normal-tension glaucoma: can we avoid the pitfalls?

Abstract

Routine neuroimaging for patients with presumed normal-tension glaucoma (NTG) is a contentious issue and it has been suggested that it may be unnecessary due to the low yield for detecting intracranial pathology. However, it has also been reported that 8% of patients diagnosed with NTG have associated compressive lesions of the anterior visual pathways. We present three patients in whom the initial diagnosis of NTG was eventually revealed to be chiasmal compression secondary to a pituitary tumour. Case 1: a 79-year-old woman was treated for NTG for several months before a bitemporal haemianopia developed and imaging showed a pituitary tumour. Case 2: an 83-year-old man was treated for NTG while a magnetic resonance imaging (MRI) scan was requested routinely. This subsequently revealed a pituitary tumour. Case 3: a 52-year-old man with left inferior arcuate visual field loss plus disc pallor was treated for NTG. His visual field deteriorated over 8 years, despite his intraocular pressure (IOP) being well controlled. An MRI was eventually requested, which revealed a pituitary tumour. All of our patients had signs that, with hindsight, should have raised suspicions about the presumptive diagnosis of NTG and initiated neuroimaging at an earlier stage. Whilst compression of the anterior visual pathways is an uncommon finding in patients thought to have NTG, features such as bitemporal field loss, optic disc pallor, poor colour vision and, particularly, poor disc/field correlation should alert the clinician to the possibility of an intracranial mass lesion.

<p>Variable structure and function relationship of compressive optic neuropathy at the time of diagnosis</p>

“…It is interesting, from a diagnostic perspective, how CON eyes can present to a possible range from acute to chronic features at the time of diagnosis. From a retrospective review in our patients and literature, CON eyes with very slow progression and a mild degree of peripheral visual field loss may present as normal tension glaucoma masquerade at the beginning, but later suspected for CON when visual field progression seems to respect the vertical midline 26,27. However, a mild degree of visual field loss can sometimes be identified in CON eyes with a relatively more rapid progression in the following situations.…”

Macular Ganglion Cell Analysis Determined by Cirrus HD Optical Coherence Tomography for Early Detecting Chiasmal Compression

“…Both compressive and glaucomatous optic neuropathies are generally slow, progressive processes and are accompanied by optic cup excavation and enlargement. The difficulty in distinguishing between glaucomatous optic neuropathy and compressive optic neuropathy, especially in eyes with NTG, has been previously reported [ 27 , 28 ]. Funduscopic characteristics such as optic disc cupping and pallor of the neuroretinal rim are considered the important hallmarks for NTG and compressive optic neuropathy, respectively.…”

Neuropathie optique compressive secondaire à un macroadénome hypophysaire

“…Cependant, ces altérations périmétriques peuvent, parfois, mimer celles observées au cours du glaucome. Drummond et al [5] ont rapporté les observations de trois patients qui étaient considérés comme atteints de glaucome à pression normale (GPN) avec des altérations périmétriques typiques et dont l exploration neuroradiologique a révélé une tumeur intrasellaire comprimant le chiasma optique. Ahmed [6] a trouvé, parmi 62 patients ayant un GPN et des altérations périmétriques typiques de glaucome, quatre patients (6,5 %) qui présentaient une compression des voies optiques antérieures.…”