Central Retinal Vein Occlusion (CRVO)

Updated: Nov 17, 2022
  • Author: Lakshmana M Kooragayala, MD; Chief Editor: Douglas R Lazzaro, MD, FAAO, FACS  more...
  • Print
Overview

Background

Central retinal vein occlusion (CRVO) is a common retinal vascular disorder. Clinically, CRVO presents with variable visual loss; the fundus may show retinal hemorrhages, dilated tortuous retinal veins, cotton-wool spots, macular edema, and optic disc edema.{ref7578-INVALID REFERENCE} Note the images below.

Recent onset central retinal vein occlusion, showi Recent onset central retinal vein occlusion, showing extensive hemorrhages in the posterior pole and giving the "blood and thunder appearance."
Peripheral fundus view of the same patient with ce Peripheral fundus view of the same patient with central retinal vein occlusion as in the previous image, showing hemorrhages extending all over the fundus.
Fluorescein angiograph of same patient with centra Fluorescein angiograph of same patient with central retinal vein occlusion as in previous images, showing hypofluorescence due to blockage from hemorrhages in the retina. It is not useful to perform a fluorescein angiogram in acute stages of the disease.
Fundus picture of the same patient with central re Fundus picture of the same patient with central retinal vein occlusion as in previous images, showing resolving neovascularization of the disc and panretinal photocoagulation scars.
Fluorescein angiogram of the same patient with cen Fluorescein angiogram of the same patient with central retinal vein occlusion as in the previous images, taken more than 1 year later, showing persistent cystoid macular edema with good laser spots.

In view of the devastating complications associated with the severe form of CRVO, a number of classifications were described in the literature. All of these classifications take into account the area of retinal capillary nonperfusion and the development of neovascular complications. [1, 2, 3, 4, 5]

Broadly, CRVO can be divided into 2 clinical types, ischemic and nonischemic. In addition, a number of patients may have an intermediate presentation with variable clinical course. On initial presentation, it may be difficult to classify a given patient into either category, since CRVO may change with time.

A number of clinical and ancillary investigative factors are taken into account for classifying CRVO, including vision at presentation, presence or absence of relative afferent pupillary defect, extent of retinal hemorrhages, cotton-wool spots, extent of retinal perfusion by fluorescein angiography, and electroretinographic changes.

Nonischemic CRVO is the milder form of the disease. It may present with good vision, few retinal hemorrhages and cotton-wool spots, no relative afferent pupillary defect, and good perfusion to the retina. Nonischemic CRVO may resolve fully with good visual outcome or may progress to the ischemic type. Note the images below.

Patient with nonischemic central retinal vein occl Patient with nonischemic central retinal vein occlusion presented with dilated, tortuous veins and superficial hemorrhages.
Fundus picture of the same patient with central re Fundus picture of the same patient with central retinal vein occlusion as in previous image, showing resolved hemorrhages and pigmentary changes in the macula several months later.

Ischemic CRVO is the severe form of the disease. CRVO may present initially as the ischemic type, or it may progress from nonischemic. Usually, ischemic CRVO presents with severe visual loss, extensive retinal hemorrhages and cotton-wool spots, presence of relative afferent pupillary defect, poor perfusion to retina, and presence of severe electroretinographic changes. In addition, patients may end up with neovascular glaucoma and a painful blind eye.

Next:

Pathophysiology

The exact pathogenesis of the thrombotic occlusion of the central retinal vein is not known. Various local and systemic factors play a role in the pathological closure of the central retinal vein. [3, 6, 7]

The central retinal artery and vein share a common adventitial sheath as they exit the optic nerve head and pass through a narrow opening in the lamina cribrosa. Because of this narrow entry in the lamina cribrosa, the vessels are in a tight compartment with limited space for displacement. This anatomical position predisposes to thrombus formation in the central retinal vein by various factors, including slowing of the blood stream, changes in the vessel wall, and changes in the blood.

Arteriosclerotic changes in the central retinal artery transform the artery into a rigid structure and impinge upon the pliable central retinal vein, causing hemodynamic disturbances, endothelial damage, and thrombus formation. This mechanism explains the fact that there may be an associated arterial disease with central retinal vein occlusion (CRVO). However, this association has not been proven consistently, and various authors disagree on this fact.

Thrombotic occlusion of the central retinal vein can occur as a result of various pathologic insults, including compression of the vein (mechanical pressure due to structural changes in lamina cribrosa, eg, glaucomatous cupping, inflammatory swelling in optic nerve, orbital disorders); hemodynamic disturbances (associated with hyperdynamic or sluggish circulation); vessel wall changes (eg, vasculitis); and changes in the blood (eg, deficiency of thrombolytic factors, increase in clotting factors).

Occlusion of the central retinal vein leads to the backup of the blood in the retinal venous system and increased resistance to venous blood flow. This increased resistance causes stagnation of the blood and ischemic damage to the retina. It has been postulated that ischemic damage to the retina stimulates increased production of vascular endothelial growth factor (VEGF) in the vitreous cavity. Increased levels of VEGF stimulate neovascularization of the posterior and anterior segment (responsible for secondary complications due to CRVO). Also, it has been shown that VEGF causes capillary leakage leading to macular edema (which is the leading cause of visual loss in both ischemic CRVO and nonischemic CRVO).

The prognosis of CRVO depends upon the reestablishment of patency of the venous system by recanalization, dissolution of clot, or formation of optociliary shunt vessels.

Previous
Next:

Epidemiology

Frequency

United States

Central retinal vein occlusion (CRVO) and branch retinal vein occlusion constitute the second most common retinal vascular disorder. The nonischemic type is more common than the ischemic type.

The Beaver Dam Eye Study Group reported the 15-year cumulative incidence of CRVO to be 0.5%. [8]

International

A large population-based study in Israel reported a 4-year incidence of retinal vein occlusion of 2.14 cases per 1000 of general population older than 40 years and 5.36 cases per 1000 of general population older than 64 years.

In Australia, the prevalence of vein occlusion ranges from 0.7% in patients aged 49-60 years to 4.6% in patients older than 80 years. [9]

Pooled data from population studies from the United States, Europe, Asia, and Australia show that CRVO affects 0.8 per 1000 persons. [10]

Mortality/Morbidity

CRVO is not associated directly with increased mortality.

Nonischemic CRVO may resolve completely without any complications in about 10% of cases. In about 50% of patients, vision may be 20/200 or worse. One third of patients may progress to the ischemic type, commonly in the first 6-12 months after presentation.

In more than 90% of patients with ischemic CRVO, final visual acuity may be 20/200 or worse. Anterior segment neovascularization with associated neovascular glaucoma develops in more than 60% of cases. This can happen within a few weeks and up to 1-2 years afterward.

It has been reported that the fellow eye may develop retinal vein occlusion in about 7% of cases within 2 years. In another report, the 4-year risk of developing second venous occlusion is 2.5% in the same eye and 11.9% in the fellow eye. Neovascular glaucoma may result in a painful blind eye.

Race

CRVO does not have any particular racial preference.

Sex

CRVO occurs slightly more frequently in males than in females.

Age

More than 90% of CRVO occurs in patients older than 50 years, but it has been reported in all age groups.

Previous
Next:

Prognosis

For nonischemic CRVO, complete recovery with good visual recovery occurs only in about 10% of cases. Fifty percent of patients will have 20/200 or worse vision. About one third of patients convert to ischemic CRVO. CVOS noted that, of 547 eyes initially diagnosed to have nonischemic central retinal vein obstructions, 185 (34%) progressed to become ischemic central retinal vein obstructions within 3 years; 15% converted within the first 4 months.

For ischemic CRVO, more than 90% of patients will have 20/200 or worse vision. About 60% of patients develop ocular neovascularization with associated complications. About 10% of patients can develop CRVO or other type of vein occlusions within either the same eye or the contralateral eye within 2 years.

The long-term prognosis of CRVO has significantly improved with new anti-VEGF agents and steroids, maintaining good visual acuity for a long duration in most patients, except those with severe ischemic maculopathy. Development of neovascular complications has also decreased with continued monitoring and anti–VEGF treatment.

Despite promising advances with anti-VEGF therapy, select patients are unresponsive to therapy. The recent IMAGINE study reports possible association of cytokine expression to higher order OCT features and treatment response in retinal vein occlusion. This type of information on OCT imaging could enhance treatment decision-making and provide additional prognostic indicators. [11]

COVID-19 infection is implicated with various systemic and ocular complications. Irrespective of the traditional risk factors, hypercoagulability associated with COVID-19 can be a factor in the development of CRVO.Timely initiation of appropriate treatment could bring about complete resolution of the disease with good prognosis for most of the patients. [12]

 

Previous
Next:

Patient Education

Good control of systemic medical problems is important, as are regular medical and ophthalmologic checkups.

Previous