CaseWise 11

Peripapillary Edema from Hemi-central Retinal Vein Occlusion: A Red Herring in the Evaluation of the Retinal Nerve Fibre Layer.

Dr. Shreya Jaiswal, Dr. Sarang Lambat, Dr. Vinay Nangia 
Suraj Eye Institute, Nagpur

Introduction
The retinal nerve fibre layer (RNFL) assessment is a key factor for management of glaucoma. Presence of coexisting ocular disease has an impact on the RNFL and precludes its accurate assessment. It was the purpose to highlight the nuances in RNFL analysis with other ocular findings.

Case Report
A male, 65 years of age, came with chief complaints of sudden, non progressive and painless diminution of vision in left eye since 1 day. He was a known case of Hypertension and Ischaemic heart disease. He has been under treatment for primary open angle glaucoma (POAG) for the past 20 years and had undergone trabeculectomy with cataract extraction with lens implantation in left eye in November 2012 and in right eye in January 2018. On clinical examination his best corrected visual acuity (BCVA) was 6/6, N6 in right eye and counting finger 3m, N36 in left eye. Slit-lamp biomicroscopy showed functional bleb, patent surgical peripheral iridectomy and intraocular lens in both eyes. Intraocular pressure recorded by Goldmann applanation tonometry was 16 mmHg in both eyes. Fundus examination of right eye showed a vertical cup disc ratio (VCDR) of 0.9:1 and pale neuroretinal rim. Left eye showed glaucomatous disc, edema and haemorrhages in superior half of retina involving macula (Fig 1). Spectral domain optical coherence tomography of right eye showed RNFL thinning in all the 6 sectors and left eye showed RNFL thinning in infero-temporal sector with significant increase in RNFL thickness superiorly, as compared to the previous scan (Fig 2-5) and cystoid edema with sub sensory fluid at macula (Fig 6).

Figure 1 : Colour fundus photograph of right eye showing glaucomatous disc and left eye showing glaucomatous disc, edema and haemorrhages in superior half of retina involving macula. 
Figure 2 : Right eye RNFL scan from previous OCT of 31/01/2018, showing RNFL thinning in all the 6 sectors.
Figure 3 :Left eye RNFL scan from previous OCT of 31/01/2018, showing RNFL thinning in all sectors except superonasal sector.
Figure 4 : Right eye RNFL scan from present OCT of 22/05/2019 showing RNFL thinning in all the 6 sectors.
Figure 5 : Left eye RNFL scan from present OCT of 22/05/2019 showing RNFL thinning in inferotemporal sector with significant edema of RNFL superiorly. 
Figure 6 : Line scan passing through macula, showing normal macula in right eye and cystoid macular edema in left eye with sub sensory fluid. 

Discussion
Patients of primary open angle glaucoma are predisposed to development of vein occlusion.3 Vein occlusion causes peripapillary oedema resulting in thickening of RNFL in the involved segment, and may obscure the pre existing  glaucomatous RNFL damage in such patients.1,2 A knowledge of previous history and availability of clinical documentation may help in identifying such patients. The followup scans are also important in understanding the severity of the pre-existing condition. It is important to assess the RNFL image on SDOCT to identify the RNFL swelling and determine the accuracy of the RNFL segmentation. If the pre existing glaucomatous damage is severe it may be difficult to assess clinically and on imaging the peripapillary area for extent of RNFL loss in such patients.

References

  1. Hitchings RA, Spaeth GL. Chronic retinal vein occlusion in glaucoma. British Journal of Ophthalmology. 1976 Oct 1;60(10):694-9.DOI: 10.1136/bjo.60.10.694
  2. Kim CS, Shin KS, Lee HJ, Jo YJ, Kim JY. Sectoral retinal nerve fiber layer thinning in branch retinal vein occlusion. Retina. 2014 Mar 1;34(3):525-30. DOI: 10.1097/IAE.0b013e3182a2e746 
  3. Park HY, Jeon S, Lee MY, Park CK. Glaucoma progression in the unaffected fellow eye of glaucoma patients who developed unilateral branch retinal vein occlusion. American journal of ophthalmology. 2017 Mar 1;175:194-200.  DOI – 10.1016/j.ajo.2016.10.009
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