Spark ImageWise 20

Perforating scleral vessels 

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

Case Description
A female, 70 years of age, came for a routine examination. She had a history of systemic hypertension and hypothyroidism since 20 years and diabetes mellitus since 4 years. She had a history of cataract extraction with intraocular lens implantation surgery done in both eyes 15 years back, and 3 doses of intravitreal anti vascular endothelial growth factor (VEGF) injection in left eye 11 years back. Her best corrected visual acuity was 6/12, N18 in right eye and 6/36, N36 in left eye. She had an axial length of 28.93 mm in right eye and 27.50 mm in the left eye. Anterior segment examination showed pseudophakia in both eyes. Intraocular pressure was 12 mmHg and 16 mmHg in right and left eye respectively.

Figure 1 shows colour fundus photograph of right eye with clear media, a horizontally oval disc with a vertical cup to disc ratio of 0.4:1 and a large parapapillary atrophy (Yellow arrow). There is presence of a small well defined patchy chorioretinal atrophy (Green arrow) along the inferior arcade and choroidal tessellations, suggestive of category 3 Myopic macular degeneration.
Figure 2 shows colour fundus photograph of left eye with clear media, a horizontally oval disc and a vertical cup to disc ratio of 0.8:1 with large parapapillary atrophy (Yellow arrow). There is a large chorioretinal atrophy involving macula (Green arrow) with choroidal tessellations, suggestive of category 4 myopic macular degeneration.
Figure 3 shows retinal nerve fibre layer (RNFL) thickness map from SD-OCT, which shows significant thinning superotemporally and superonasally and early thinning inferiorly (blue arrow).
Figure 4 shows SD-OCT RNFL thickness map, which shows normal thickness of RNFL in all the quadrants.
Figure 3 (OD) shows a line scan of spectral domain optical coherence tomography of right eye, showing presence of a uniform hypo-reflective structure running through the outer part of sclera and along the scleral curvature (Red arrows) which is probably long posterior ciliary artery (LPCA), as the LPCA is known to run through the outer part of sclera to reach the anterior segment and form the major arterial circle along with anterior ciliary artery which supplies anterior segment of eye. 
Another hypo-reflective structure (Yellow arrow) can be seen bifurcating and forming a direct communication with the choroid at the posterior pole, most likely being the short posterior ciliary artery supplying the choroid and retina.
Figure 4 (OD) shows a line scan of a different section of the same eye, showing presence a linear hypo-reflective structure (Blue arrows) along the scleral curvature in its inner part probably draining the choroid and is seen to join a uniform sac like hypo-reflective structure suggestive of  a posteriorly located ampulla of a draining vein ( blue arrowheads), and then exiting through the sclera. 

Discussion

A decrease in the choroidal and scleral thickness is often noted with high myopia, which allows better visualisation of deeper structures such as blood vessels within the sclera, using an SD-OCT. Our patient was a highly myopic patient, where we could see the presence of long and short ciliary artery along with possible draining macular vortex vein. However, it is possible to understand the choroidal vasculature  better using  indocyanine green angiography. The OCT does however outline vessels in the sclera that go to  supply and or drain the choroid or sub Bruch’s Retinal Pigment Epithelial  area  when the choroid thins considerably. 

Studies by Querques G et.al (3) and Ishida T et.al (4) suggest a significant correlation of presence of lacquer cracks and choroidal neovascular membrane with perforating scleral vessels. Thus it is important to study the intra-scleral vascular structures as any alterations in these may lead to development of chorio-retinal complications or optic nerve damages in patients with pathologic myopia.  These vessels  may also prove to be important  in early identification of  choroidal  and outer retinal changes and may be a  target for development of ocular vascular therapies in the future. 

ReadWise

  1. Quaranta M, Arnold J, Coscas G, Francais C, Quentel G, Kuhn D, Soubrane G. Indocyanine green angiographic features of pathologic myopia. American journal of ophthalmology. 1996 Nov 1;122(5):663-71. https://doi.org/10.1016/S0002-9394(14)70484-2
  2. Ohno-Matsui K, Morishima N, Ito M, Yamashita S, Futagami S, Tokoro T, Nakagawa T. Indocyanine green angiography of retrobulbar vascular structures in severe myopia. American journal of ophthalmology. 1997 Apr 1;123(4):494-505. https://doi.org/10.1016/S0002-9394(14)70175-8
  3. Querques G, Corvi F, Balaratnasingam C, Casalino G, Parodi MB, Introini U, Freund KB, Bandello F. Lacquer cracks and perforating scleral vessels in pathologic myopia: a possible causal relationship. American journal of ophthalmology. 2015 Oct 1;160(4):759-66. https://doi.org/10.1016/j.ajo.2015.07.017
  4. Ishida T, Watanabe T, Yokoi T, Shinohara K, Ohno-Matsui K. Possible connection of short posterior ciliary arteries to choroidal neovascularisations in eyes with pathologic myopia. British Journal of Ophthalmology. 2019 Apr 1;103(4):457-62. http://dx.doi.org/10.1136/bjophthalmol-2018-312015 

Correspondence 

Dr Vinay Nangia
MS, FRCS, FRCOphth
Director 
Suraj Eye Institute
Nagpur
Email –education@surajeye.org

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