Spark ImageWise 4- Glaucoma

Border Tissue of Elschnig

Dr. Shreya Jaiswal, Dr. Prabhat Nangia, Dr. Sarang Lambat, Dr. Vinay Nangia 
Suraj Eye Institute, 559 New colony, Nagpur, India

Case Description
A female 14 years of age, came for a routine examination. She had no significant past systemic history. Autorefractometer reading showed a value of -9.00 +2.25 @ 90 in right eye and -9.50 +2.25 @ 90 in left eye. She was accepting -8.00 +1.50 x 90 in both eyes. Her best corrected visual acuity was 6/6(p), N6 in both eyes. Anterior segment examination was within normal limits in both eyes with an intraocular pressure of 16 mmHg in both eyes. Her central corneal thickness was 544 microns in right eye and 548 microns in left eye. Her axial length was 26.28 mm in right eye and 26.39 mm in left eye.

Figure 1a and 1b shows colour fundus photograph centred at the macula of right eye and left eye respectively, it shows clear media, an obliquely oriented disc in the RE and a circular disc in the left eye. There was presence of parapapillary atrophy present temporally in both eyes. Blood vessels appear normal and there is presence of bright foveal reflex and choroidal tessellations.
Figure 2 shows spectral domain optical coherence tomography (SD-OCT) of multiple sections of line scan passing through the disc of the right eye. Figures A-D show presence of a hyper reflective structure – the border tissue of Elschnig – at the border of the Optic disc, seen reaching the optic disc margin (Red dot). The edge of Bruch’s membrane is identified by the blue dot. The border tissue of Elschnig(yellow arrow) is also seen to separate the choroid from retinal ganglion cell axons as they pass through the neural canal.

Discussion 

The border tissue of Elschnig is widely accepted as the structure underpinning the fundoscopic appearance of the optic disc margin in human eyes. The ring of Elschnig comprises the border tissue of Elschnig, which is collagenous tissue arising from the sclera to join Bruch’s membrane. This separates the choroid from the retinal ganglion cell axons as they pass through the anterior portion of the neural canal. The margin of the disc as seen clinically often depends on an interplay of various parapapillary tissues including the Bruch’s membrane, Tissue of Elschnig and the Sclera-lamina cribrosa interface. The Elsching’s tissue has various orientations and is not standard in size or shape. It’s shape and three dimensional structure is defined by the axial length, by the position of the sclera and the Bruch’s membrane. The border tissue can get stretched temporally, with axial length enlargement in association with the development of the scleral flange as the Bruch’s membrane moves temporally with the development of the Gamma zone parapapillary atrophy. In such a situation there is often difficulty in distinguishing the Elschnig’ tissue from the underlying stretched and thin sclera and in some instances also it may be difficult to distinguish it from the Bruch’s membrane, when the Bruch’s membrane continues to be part of the parapapillary atrophy. While the exact clinical significance of this tissue is not well understood, it does appear to be an integral part of the margin architecture of the optic disc.

ReadWise 

  1. Kim M, Kim TW, Weinreb RN, Lee EJ. Differentiation of parapapillary atrophy using spectral-domain optical coherence tomography. Ophthalmology. 2013 Sep 1;120(9):1790-7. https://doi.org/10.1016/j.ophtha.2013.02.011
  2. Anderson DR, Hoyt WF. Ultrastructure of intraorbital portion of human and monkey optic nerve. Archives of Ophthalmology. 1969 Oct 1;82(4):506-30. doi:10.1001/archopht.1969.00990020508017
  3. Reis AS, Sharpe GP, Yang H, Nicolela MT, Burgoyne CF, Chauhan BC. Optic disc margin anatomy in patients with glaucoma and normalcontrols with spectral domain optical coherence tomography. Ophthalmology. 2012 Apr 1;119(4):738-47. https://doi.org/10.1016/ j.ophtha.2011.09.054

Correspondence 
Dr Vinay Nangia
MS, FRCS, FRCOphth
Director 
Department of ophthalmology
Suraj eye Institute
Email –education@surajeye.org

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