Keywords
congenital retinal macrovessel - fovea - optical coherence tomographic angiography
Introduction
Brown et al used the term congenital retinal macrovessel (CRM) to describe an abnormal
retinal vessel, generally a vein, that extends through the central macula, supplying
or draining regions above and below the horizontal raphe. This abnormality is frequently
unilateral and seldom affects vision.[1] CRM was later categorized as a type (stage 1) of arteriovenous malformation of the
retina by Archer et al.[2]
Optical coherence tomography angiography (OCTA) now allows for noninvasive imaging
of retinal vasculature and segmentation of the superficial and deep vascular layers.[3]
This case report was conducted in adherence to the principles of the Helsinki Declaration.
It was authorized by the ethical board of Benghazi Ophthalmology Teaching Hospital,
and informed written permission was acquired after discussing the study with the patient.
In this study, we present the case of a patient with a CRM crossing the foveal avascular
region, with no visual defect or macular thickening.
Case Presentation
A 57-year-old woman presented to the ophthalmology (OPD) asking for changing her reading
glasses. On examination, both eyes' best corrected visual acuity was 0.9, intraocular
pressure was within normal limits, and anterior segment examination was normal. Posterior
segment examination with +90-D lens revealed no abnormality in the right eye, while
in the left eye, it showed an abnormal, large retinal vein (macrovessel) branching
superiorly from the inferotemporal vein, with numerous tributaries crossing the horizontal
raphe across the macula, adjacent to the fovea. A color fundus photograph of both
eyes is shown in [Fig. 1].
Fig. 1 Color fundus photographs of the right eye (OD) and left eye (OS), showing a left
eye macrovessel.
Optical coherence tomography (OCT) was done; the left eye showed a small hyperreflective
lesion corresponding to the location of the macrovessel (see [Fig. 2]).
Fig. 2 Optical coherence tomography (OCT), showing a normal right eye (OD) and a small hyperreflective
lesion (arrow) corresponding to the location of the macrovessel in the left eye (OS).
Optical coherence tomographic angiography (OCTA; DRI OCT Triton plus, Topcon Medical
Systems, Inc., Europe) was normal for the right eye. It detected no alterations, except
for the presence of the macrovessel branching superiorly at the edge of the fovea,
a vascular zone in the left eye ([Fig. 3]).
Fig. 3 A 3 × 3 mm en face optical coherence tomographic angiography (OCTA) images of the
left eye (OS). Images were segmented into superficial (upper limit: 0 µm from the
internal limiting membrane; lower limit: 15 µm posterior to the inner plexiform layer
[IPL]) and deep (upper limit: 15 mm posterior to the IPL; lower limit: 70 µm posterior
to the IPL) showing large retinal vessels branching superiorly at the edge of the
fovea, a vascular zone (arrow).
Discussion
CRM is a rare vascular abnormality of the macular region that is usually discovered
incidentally.[4]
The majority of cases of CRM are asymptomatic and stationary, although they have been
described in association with other retinal alterations such as macular hemorrhages,
preretinal hemorrhages, perifoveal microvascular alterations,[5] central serous choroidopathy,[6] arterial macroaneurysms,[7] retinopathy of prematurity,[8] vascular occlusion, cystic macular edema (which resolves spontaneously after a few
months),[9]
[10] vascular malformations of the central nervous system,[9]
[11] and reduced retinal sensitivity at the macular area.[12]
Although the CRMs are apparent and stable vessels that cross the foveal avascular
zone, a fundus examination may not always reveal their existence. Therefore, in the
case of unexplained vision loss, the ophthalmologist should investigate such a rare
possibility.[5]
OCTA has been proven to be a viable method for imaging the superficial and deep vascular
layers of the retina. It is quick, noninvasive, and does not need fluorescein dye.[13]
Conclusion
In conclusion, CRM or aberrant vessels are incidental findings that, with rare exceptions,
do not cause any alteration to the patient's vision. They can be imaged by OCTA and
need to be differentiated from other retinal pathologies.
