Retinal Vascular Tortuosity

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Article initiated by:

Ahmed F Shakarchi, Ahmed Sallam, MD PhD FRCOphth

All contributors:

Fatma Shakarchi, Ahmed F Shakarchi

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Definition

Retinal vascular tortuosity is a clinical sign observed on fundoscopic examination. It refers to the abnormal twisting, turning, or coiling of retinal blood vessels. It can affect the arteries, veins, or both, and can manifest in the central retina, peripheral areas, or both. The etiology can be congenital or acquired, and it is often associated with a variety of systemic and ocular conditions.

Etiology / Differential diagnosis

Arterial tortuosity

Congenital Conditions:

1. Coarctation of the Aorta (CoA):
   • Tortuosity of retinal arteries is reported in 70% of patients.
   • Corkscrew (U-shaped) arterial tortuosity is common in the upper body.
2. Retinopathy of Prematurity (ROP) and Plus Disease:
   • Engorged tortuous vessels may be seen in active ROP with plus disease.
   • Arteriolar tortuosity can persist subsequently in patients with history of ROP

Hereditary Conditions:

1. Ehlers-Danlos Syndromes (EDS):
   • Ehlers-Danlos Syndromes is a group of connective tissue diseases with various skeletal abnormalities. According to one study, retinal arteriolar tortuosity was noted in first-order retinal arterioles in 84.9% of patients and macular arterioles in 35.8%, while 1.9% of eyes showed arteriovenous involvement.
2. Loeys-Dietz Syndrome:
   • Loeys-Dietz Syndrome is a rare multisystem genetic connective tissue disorder. Some of the ocular manifestations include mild myopia, strabismus, decreased corneal thickness, cataracts and blue sclerae. Retinal arteriolar tortuosity may be noted in about 50% of eyes in one study.
3. Familial Retinal Arteriolar Tortuosity:
   • Familial retinal arteriolar tortuosity is a rare disorder with autosomal dominant inheritance. This disease is characterized by progressive tortuosity of second and third-order arterioles in macular and peripapillary areas first noted during childhood or early adulthood. Patients can develop retinal hemorrhages spontaneously or following minor trauma. These hemorrhages typically resolved with sequalae and visual acuity tends to be normal in these patients.
4. Hereditary Endotheliopathy with Retinopathy, Nephropathy, and Stroke (HERNS):
   • Autosomal dominant inheritance, linked to the pathogenic gene 3p21 hereditary vascular retinopathy.
5. Hereditary Infantile Hemiparesis, Retinal Arteriolar Tortuosity, and Leukoencephalopathy:
   • Not linked to the 3p21 hereditary vascular retinopathy.

Acquired Conditions:

1. Coats Disease:
   • Occasionally, vascular anomalies may appear in the affected eye or the fellow eye, such as macular macro vessels or arterial tortuosity.
2. Hypertensive Retinopathy:

Venous tortuosity

Congenital / Hereditary:

1. Idiopathic retinal venous tortuosity

Outflow Resistance:

1. Retinal Vein Occlusion (RVO):
   • In a review of patients with both central and branch retinal vein occlusions, vascular tortuosity and kinking were observed not only in the impacted eyes but also in fellow eyes without frank retinal vein occlusions.
2. Papillophlebitis (PP):
   • Presents like incomplete CRVO, typically in young, healthy females, with variable retinal venous dilation and tortuosity, vitreous cell, and intraretinal hemorrhages.
3. Papilledema:
   • Venous dilation and tortuosity are associated with moderate to severe papilledema.
4. Tumors:
   • Tumors of the optic nerve or orbital tumors compressing the optic nerve can interfere with venous return causing increased venous pressure and tortuosity.

Venous stasis:

1. Polycythemia
2. Hyperviscosity syndrome:
   • this is usually related to increased serum protein, such as immunoglobulins in plasma cell dyscrasias (eg, multiple myeloma and Waldenstrom Macroglobulinemia). There may be associated retinal hemorrhages and disc edema.

High Flow States:

1. Anemia:
   • The retinal venous tortuosity has been proposed to be directly related to the severity of anemia. In patients with beta-thalassemia major, it has been found that the increased retinal venous tortuosity is related to the duration of anemia.
2. Carotid-cavernous sinus fistula

Tortuosity of both arteries and veins

Congenital/hereditary:

1. Crowding of intraocular structures / small eye
   • High hyperopia: Myopic eyes are associated with straighter arterioles, while hyperopic eyes exhibit more tortuous retinal vessels.
   • Nanophthalmos
2. Optic Nerve Hypoplasia (ONH):
   • Tortuous retinal arterioles and venules, potentially indicating endocrine abnormalities.
3. Vascular malformation
   • Arteriovenous fistula
     • Wyburn-Mason syndrome: Unilateral tortuous dilated retinal vessels secondary to arteriovenous shunts. It can be associated with vascular malformations in the brain.
     • Von-Hippel Lindau syndrome: Vascular tortuosity associated with hemangioblastomas.
   • Sturge-Weber syndrome: associated with mild tortuosity of retinal vessels, and scattered pigmentary changes.

Acquired

1. Hypotony:
   • Low intraocular pressure leads to infolding of ocular structures causing the typical fundus abnormalities, including chorioretinal folds, optic nerve head edema, and vascular tortuosity.
2. Epiretinal membrane (ERM):
   • Traction on the retina and blood vessels can cause tortuosity. This can be seen with primary ERM as well as secondary epiretinal membranes, such as proliferative vitreoretinopathy (PVR).
3. Hypertensive retinopathy
4. Inflammation
   • Posterior scleritis

Workup

The first step in finding the etiology of this clinical sign is determining whether the tortuosity is localized or involving the entire fundus, bilateral or unilateral, and whether it involves veins, arteries or both. Localized tortuosity points to a focal lesion such as an epiretinal membrane or hemangioblastoma associated with Von-Hippel Lindau disease. Bilateral tortuosity is suggestive of congenital or systemic (such as hyperviscosity syndrome) etiology, whereas unilateral tortuous vessels with disc swelling or atrophy can point to an orbital mass lesion. Intraocular pressure must be measured to exclude hypotony maculopathy. B-scan ultrasonography can be useful to assess for posterior scleritis in unilateral vascular tortuosity, particularly when associated with vitritis, visual loss and eye pain. Fluorescein angiography is rarely needed when a vascular etiology is suspected but cannot be determined from the examination and other imaging studies.

Management

Treatment of retinal vascular tortuosity is aimed at identifying the cause and treating it if necessary.

Prognosis

It largely depends on the underlying condition and the presence of any associated retinal or systemic conditions.

Conclusion

Retinal vascular tortuosity is a clinical sign characterized by the abnormal twisting of retinal vessels, which may be congenital or acquired. Identifying the underlying cause is crucial for effective management.