Asymmetric Corneal Neuropathy In A Case Of Unilateral Central Retinal Vein Occlusion

Central retinal vein occlusion (CRVO) presents with disruption of retinal venous circulation. Systemic hypertension, atherosclerosis and diabetes are all major risk factors.  Fundus floressein angiography (FFA) and optical coherence tomography (OCT) can be used for diagnosis and follow up. In vivo confocal microscopy(IVCM) is a rapid and non-invasive tool to analyze corneal layers and subbasal nerve plexus. Main morphological and densitometric measures used to assess the subbasal nerve plexus are;cornea nerve fiber density(CNFD), cornea nerve branch density (CNBD) and cornea nerve fiber length (CNFL). We aimed to investigate the difference of corneal sensitivity and changes of corneal subbasal nerve plexus in a patient with unilateral CRVO.

Case was treated, evaluated and followed up at Erciyes University Hospital Department of Ophthalmology.

60 year old male patient with comorbidities of diabetes and systemic hypertension has a history of CRVO in the right eye 6 months before. He had 3 doses of intravitreal Bevacizumab and one session of retinal fotocoagulation therapy regarding retinal areas of ischemia. Best corrected visual acuity (BCVA) was counting fingers at 1.5 meters for the right eye and 0.9 in the left eye. Biomicroscopic evaluation was normal and showed no sign of anterior segment neovascularization. Fundoscopic evaluation of the right eye showed an ischeamic retina with retinal photocoagulation, optic disc pallor and no macular edema. Left eye was normal. Corneal sensitivity measured with Cochet-Bonnet Esthesiometer showed a significant decrease of corneal sensitivity in the right eye (0,80g/mm²) compared to the left eye (0,38g/mm²). Corneal nerve fiber density was 20,6450 n/mm² for the right eye and 35,1419 n/mm² for the left eye. Corneal nerve branch density was 12,3711 n/mm² for the right and 20,6716 n/mm² for the left eye. Last of all, CNFL was 6,9427 mm/mm² for the right and 14,0525 mm/mm² for the left eye. All IVCM parameters were significantly decreased in the eye with CRVO. 

Corneal sensitivity loss and alterations of the corneal nerve structures of two eyes of the same person could be different due to various ophthalmological pathologies. There are studies investigating the relationship between corneal neuropathy and diabetic polyneuropathy and other neurodegenerative diseases. To the best of our knowledge, there are no studies regarding retinal vein occlusions, other retinal vascular diseases and corneal sensitivity and corneal nerve structural changes. Further case series needs to be performed.