CaseWise 7

When it’s not Glaucoma

Dr. Jyotsna Jareda, Dr. Vinay Nangia
Suraj Eye Institute, Nagpur, India

Introduction:
Optic disc cupping is most frequently associated with glaucoma. However it is also seen in non-glaucomatous lesions.¹ The clinical differentiation of glaucomatous from non-glaucomatous cupping  can be difficult. Proper history and thorough  clinical examination may help to differentiate between the two. IOP can be helpful, however when IOP falls within the normal range, the diagnosis can sometimes be less clear.
We present here a challenging case of Optic disc cupping with optic atrophy in a patient of Cerebrovascular event. 

Case report:
A male, 52 years of age, resident of Nagpur, came to us in November 2019 for glaucoma evaluation. Patient had a history of head injury in 2007 after which he developed hemiparesis due to infarct in temporo-parietal cerebral cortex. Patient was hypertensive since 4 years and was on medication for the same. Best corrected visual acuity in right eye (RE) was 6/12 and in left eye (LE) was 6/18. Slit lamp biomicroscopy was normal in both eyes (BE). IOP in RE on Applanation tonometry was 13 mmHg and in LE was 14 mmHg. Fundus examination of BE showed  horizontal oval disc with vertical C:D ratio of 0.8 (figure 1) and pale NRR. Periphery was WNL. On OCT BE showed significant RNFL thinning (figure 2). Visual fields (figure 3) showed right sided hemianopia with split fixation suggestive of neurological cause. Patient was not started on any AGM in view of normal pressure.

Discussion:
Differentiating glaucomatous cupping from non glaucomatous cupping can be difficult, however clinical and imaging clues proves to be helpful. Significant optic disc pallor more than cupping may be suggestive of non glaucomatous cause of optic disc cupping as discussed by Greenfield et al.² On perimetry, visual field defects respect the vertical midlinein neurological causes of optic disc cupping. On OCT reduced macular thickness and macular volume is noted in neurological causes of cupping. In our patient there was  significant RNFL loss seen in all the three temporal segments. ( superotemporal, temporal and inferotemporal) in both eyes. This is unlike  the loss seen in glaucoma patients, where the initial damage  involves the superotemporal and or inferotemporal segments.  Our patient has a vertical C:D ratio of 0.8 with a pale NRR, with right sided hemianopia,  strongly suggestive and indicative of a neurological cause of  cupping and disc appearance.

References :

1. Ambati BK, Rizzo JF. Non-glaucomatous cupping of the optic disc. Int Ophthalmol Clin 2001;41:139–49.DOI: 10.1097/00004397-200101000-00013
2. Gupta PK, Asrani S, Freedman SF, El-Dairi M, Bhatti MT. Differentiating glaucomatous from non-glaucomatous optic nerve cupping by optical coherence tomography. The open neurology journal. 2011;5:1..DOI: 10.2174/1874205X01105010001.
3. Greenfield DS et al.The cupped disc. Who needs neuroimaging? Ophthalmology. 1998;105(10):1866-1874.DOI: 10.1016/S0161-6420(98)91031-4