CaseWise 26

Optic disc swelling and small artery occlusion in a glaucomatous disc associated with PAMM

Dr. Neha Shah, Dr. Sarang Lambat, Dr. Vinay Nangia, Dr. Rupak Roy
Suraj Eye Institute, Nagpur, India

Introduction
Optic disc is the most important site for glaucomatous damage. Increase in the cup disc ratio, decrease in the rim width, and loss of retinal nerve fibre layer are hallmarks of optic disc damage.1 Optic neuropathy may  result in  clinical visible swelling of the optic disc and  of  the retinal nerve fibre layer.2 Development of optic neuritis in an optic disc with glaucomatous damage is considered rare. The purpose of this case description is to alert everyone to possibility of these  clinical findings.
Case Details
A lady, 76 years of age, known case of primary open angle glaucoma was on regular follow up with the institute since 2017. She was a known case of ischaemic heart disease and hypertension well under control. She had undergone both eyes cataract surgery 2 years back. She is on alpha agonist eyedrops twice a day in both eyes. She presented on 23/4/19 with blurring of vision in the right eye with a scotoma since 4 days. Vision had dropped from 6/6 to 6/9(p). Anterior Segment examination showed bilateral pseudophakia. Intra-ocular pressure in both eyes was 16mmHg. Fundus examination of the both eyes revealed 85% cupping. Right eye had multiple vessel sheathing and para-papillary cotton wool spots were seen (Fig1). On SDOCT retinal nerve fibre layer (RNFL) scan, when compared to the previous scan showed an increase in the retinal nerve fibre layer thickness (Fig 3), which lead us to the diagnosis of optic neuropathy. After obtaining complete cardiac and physician fitness 3 doses of 1mg IV methyl prednisolone was given followed by tapering doses of oral steroids, after which the vision improved to 6/6P, RNFL thickness came back to baseline and the vessels filled up (Fig 2). 6 months after this first episode she developed similar findings in her left eye also (Fig 4 and 5) . A para-central acute middle maculopathy (PAMM) was also noted with a drop in vision to 6/24 in the left eye. She was advised the same treatment again after a physician fitness.


Figure1: Multiple vessel occlusion  (Black arrow) with significant glaucomatous damage Figure 2: Filling up of vessels post treatment (Black arrow) Cotton wool spots seem much lesser
Figure3: SDOCT of the right eye showing baseline RNFL then increase in thickness and post IVMP treatment RNFL thickness decreasing
Figure 4: SDOCT showing left eye baseline RNFL, which increased in thickness in November at last follow up
Figure 5: Left eye showed glaucomatous damage disc, which developed optic neuropathy 6 months later, showing vascular sheathing (black arrow), cotton wool spots and PAMM lesion (yellow arrow)

Discussion
The increased RNFL thickness was seen in an eye with glaucomatous disc and previously documented RNFL thinning. Eyes with preexisting optic nerve involvement as in glaucomatous eyes, secondary optic disc changes need due consideration. Diagnosis of other superimposed optic nerve disorders in presence of already existing damage is a challenge. Knowledge and documentation of all past followups is critical in such situations. Involvement of the other eye is also described and hence a close follow up of the fellow eye  is of paramount importance.3 The PAMM lesion noted in this case resolved on its own which is as per the description given in literature.4 In our case it was difficult to diagnose the optic neuritis in presence of neuro – retinal rim thinning. The swelling of the RNFL could only be picked up as we had the previous scans showing an increase in the RNFL thickness. This helped us in diagnosing the neuropathy and its prompt treatment. 

References

1. Gandhi M, Dubey S. Evaluation of the Optic Nerve Head in Glaucoma. J Curr Glaucoma Pract. 2013;7(3):106‐114. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4741153/)

2. Iorga RE, Moraru A, Ozturk MR, Costin D. The role of Optical Coherence Tomography in optic neuropathies. Rom J Ophthalmol. 2018;62(1):3‐14. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5959022/)

3. Menon V, Saxena R, Misra R, Phuljhele S. Management of optic neuritis. Indian J Ophthalmol. 2011;59(2):117‐122.(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3116540/

4. Sarraf D, Rahimy E, Fawzi AA, et al. Paracentral acute middle maculopathy: a new variant of acute macular neuroretinopathy associated with retinal capillary ischemia. JAMA Ophthalmol. 2013;131(10):1275‐1287 (https://pubmed.ncbi.nlm.nih.gov/23929382/)

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