The patient had a macular hole, cataracts and numerous health problems.
Sherrol A. Reynolds
A 76-year-old white female presented to our clinics for a comprehensive
eye exam. Her ocular history was significant for a macular hole in the right
eye and cataracts in both eyes. She was being closely followed by a
vitreoretinal specialist but did not want eye surgery. Her health problems
included hypertension, hypercholesterolemia and thyroid regulation for which
she was taking medications.
Ocular exam revealed best-corrected visual acuity of 20/200 OD and 20/40
OS. There was no improvement on pinhole testing in either eye. Pupils were
equal with no relative afferent pupillary defect. Ocular motilities and
confrontation visual fields were unremarkable.
|Fundus exam revealed unusual retinal vessels superior temporal
to the optic disc and a macular hole in the right eye.
Image: Reynolds SA
Slit lamp evaluation revealed moderate nuclear sclerotic cataract in
both eyes. Intraocular pressures were 17 mm Hg OD and OS. Examination of the
retina revealed unusual retinal vessels superior temporal to the optic disc and
a macular hole in the right eye, contributing to the decreased vision in that
eye. There was a choroidal nevus in the left eye.
What is your diagnosis?
The retinal finding may demonstrate retinal neovascularization, retinal
collateral vessel, retinal arteriovenous malformations, intraretinal
microvascular abnormalities (IRMA) or retinal vessel tortuosity.
Upon further questioning, the patient reported a history of a retinal
hemorrhage in the right eye. Based on the additional information, the clinical
characteristic and location of the vessels, it was concluded that the unusual
vessels represented retinal collaterals caused by a prior vascular occlusion.
Collateral vessels play an important role in supplying oxygen to an
organ when delivery by the normal vasculature has been compromised by disease.
Henkind and Wise describe retinal collateral as dilated vessels that arise from
the pre-existing capillary bed to join adjacent vessels.
Three types of vessel formation
Three types of collateral vessel formation can occur. The first and
least commonly seen is the arterio-arteriolar (A-A) subtype, which develops
after branch artery obstruction. The second is the veno-venular (V-V) subtype,
which develops after vein obstruction. The third is the arteriovenous (A-V)
subtype, which occurs when capillary bed obstruction results from diabetic
retinopathy and long-standing glaucoma.
If there is no capillary bed obstruction, arteriovenous communication
are called shunts, which may be a congenital variation in conditions such as
racemose angioma, retinal angiomatosis and Coats disease, according to
Landa and Rosen.
The formation of collaterals is an attempt to restore blood flow to an
area of relative ischemia in cases of vascular occlusive events. Collateral
channels usually form near or adjacent to areas of nonperfusion of the
capillary bed. Ultimately, they assume a structure similar to the occluded
They may be observed several weeks to months after a vascular occlusion.
They may be single or multiple and appear as normal small blood vessels
connecting adjacent arterioles and venules or as small tortuous venous
channels. Collaterals may recede if the occluded vessel becomes patent or they
may assume the responsibility for blood flow to the affected area.
Collaterals are a frequent occurrence in branch retinal vein occlusion
(BRVO). They typically occur across the horizontal raphe or in another location
to bypass the blocked retinal segment. In patients with BRVO, the formation of
collaterals has been observed to have a favorable effect on visual prognosis,
according to Im and colleagues.
Retinochoroidal collaterals, also known as retinociliary or optociliary
shunts or opticociliary anastomoses, can occur in a central retinal vein
occlusion (CRVO). As with BRVO, Priluck and colleagues have suggested that the
occurrence of collaterals after a CRVO is associated with an improved visual
prognosis. Another variation of collateral at the optic nerve head occurs in
chronic glaucoma cases in response to compromised nerve vascular perfusion.
FA may be necessary
Clinically, collateral vessels may resemble retinal neovascularization,
so fluorescein angiography (FA) may be necessary. Neovascularization are
thin-walled, fragile vessels that may be accompanied by fibrotic scaffolding.
More importantly, neovascularization leaks on FA. Collateral vessels do not
leak fluorescein, except in their earliest stages of development. Additionally,
collaterals do not extend outside the retinal level in which they originate.
Although this patient did not have diabetes, it is important to mention
that IRMA represent a variation of collateral formation in areas of
nonperfusion in diabetic retinopathy. They are considered preneovascularization
and may leak in the early phases of FA. A retinal consultation and FA are
Collateral formation can be beneficial to the health of the retina or
optic nerve. Rapid collateralization can effectively avert total sensory
retinal loss. On the other hand, collaterals may indicate a past or present
retinal vascular event. Therefore, it becomes important to ascertain the
underlying systemic cause and manage it appropriately.
In this case, the patient reported having a prior vascular event in the
right eye and she has significant systemic risk factors. Also, a reported 10%
of patients with a retinal-vein occlusion develop an occlusion in the other eye
over time, according to Cugati and colleagues. It is important to closely
monitor patients with collateral formation. Collaterals should not be treated
by photocoagulation, which may lead to further retinal compromise.
- Cugati S, et al. Ten-year incidence of retinal vein occlusion in an
older population: The Blue Mountains Eye Study. Arch Ophthalmol.
- Henkind P, Wise GN. Retinal neovascularization, collaterals and
vascular shunts. Br J Ophthalmol. 1974; 58:413.
- Im CY, et al. Collateral vessels in branch retinal vein occlusion.
Korean J Ophthalmol. 2002;16:8287.
- Landa G, Rosen RB. New patterns of retinal collateral circulation
are exposed by a retinal functional imager (RFI). Br J Ophthalmol.
- Priluck IA, et al. Long-term follow-up of occlusion of the central
retinal vein in young adults. Am J Ophthalmol.
- Jamie Althoff, OD, is an assistant professor at Nova Southeastern
University College of Optometry. She can be reached at (954) 262-1432;
- Sherrol A. Reynolds OD, FAAO, is an associate professor at Nova.
She can be reached at (954) 262-1442; firstname.lastname@example.org.
- Edited by Leo P. Semes, OD, a professor of optometry at UAB and a
PCON Editorial Board member. He may be reached at