Central Retinal Vein Occlusion (CRVO)

Retinal vein occlusion is the blockage of one of the main veins of the retina and is one of the commonest retinal vascular occlusive disorders, usually associated with a variable degree of visual loss

Introduction

  • Retinal vein occlusion is the blockage of one of the main veins of the retina
  • It is one of the commonest retinal vascular occlusive disorders
  • Usually associated with a variable degree of visual loss
 
Retinal vein occlusion is the blockage of one of the main veins of the retina and is one of the commonest retinal vascular occlusive disorders, usually associated with a variable degree of visual loss.

Epidemiology

  • Retinal Vein Occlusion has a prevalence of 2.95%
    • Central Retinal Vein Occlusion (CRVO) 0.1-0.2%
    • Branch Retinal Vein Occlusion (BRVO) 2.74%
  • BRVO is 5.6 times more common than CRVO.
  • 90% of the patients with CRVO are older than 50 years, whereas the rest are younger in age, demonstrating that incidence of CRVO increases with age.
  • Prevalence does not differ by gender or race.
  • Retinal Vein Occlusion is the most frequent retinal vascular disorder causing a visual loss after Diabetic Retinopathy.

Anatomy

  • Blood from the inner retina drains into the Branch Retinal Veins which drain into the Central Retinal Vein. While blood from the outer retina and the choroid drains into the vortex veins of the choroid.
  • The central retinal vein exits the eye with the optic nerve by passing through the lamina cribrosa. At this point, the retinal artery and vein are enclosed in a common adventitial sheath and this is the most common point of retinal vein occlusion.
  • The vortex veins drain into the superior and inferior ophthalmic veins.
  • The superior and inferior ophthalmic veins and the central retinal vein flow into the cavernous sinuses.
  • Blood from the cavernous sinuses enters the systemic circulation via the petrosal venous sinuses and the sigmoid sinuses, which ultimately drain into the internal jugular veins.

Risk Factors

  • Older age
  • Cardiovascular disease
  • Hypertension
  • Smoking
  • Obesity
  • Arteriosclerosis
  • Diabetes
  • Hyperlipidemia
  • Vasculitides
  • Anti-phospholipid syndrome
  • Activated protein C
  • Factor V Leiden
  • Hyperviscosity syndromes
  • Hyperhomocysteinemia
  • Open angle glaucoma
  • Autoimmunee diseases
  • Collagen vascular diseases

Classification

Non Ischemic CRVO

  • This accounts for about 75-80% of the cases of CRVO
  • Visual acuity is usually better than 20/400
  • Less than 10 disc diameters of capillary nonperfusion with fluorescein angiography
  • Mild retinal hemorrhages
  • Optic disc edema with various degrees of macular edema
  • Benign and self-limiting disease

Ischemic CRVO

  • This accounts for about 20-25% of the cases of CRVO
  • Visual acuity is usually worse than 20/400
  • 10 or more disc diameters of retinal capillary nonperfusion with fluorescein angiography
  • Neovascularization resulting in glaucoma is most frequent with ischemic CRVO and causes additional complications
  • More extensive retinal hemorrhages
  • Gross retinal and macular edema.
  • Malignant disease that can get complicated by neovascularization resulting in glaucoma.

Extent of Retinal Vein Involvement

  • Branch retinal vein occlusion (BRVO)
  • Hemicentral retinal vein occlusion
  • Central retinal vein occlusion (CRVO)

Pathophysiology

Multiple mechanisms of venous occlusion are proposed as under,
  • Thickening and stiffening of the lamina cribrosa, as the person ages, may cause compression of the vascular wall.
  • Arteriosclerosis in the central retinal artery may compress the relatively thin walled central retinal vein as they both pass through the lamina cribrosa surrounded in a common adventitial sheath. Or, alternatively, a branch retinal vein getting compressed by a nearby arteriole is the main mechanism of BRVO.
  • Narrowing of the lumen of retinal vein due to above changes may result in formation of a thrombus secondary to the turbulent flow of blood. This thrombosis is the main mechanism of occlusion in CRVO.
  • Raised intra ocular pressure as in open angle glaucoma may cause external compression of the retinal vein compromising venous outflow or leading to formation of thrombus due to stasis.
  • Some evidence of local inflammatory etiology is also found.

Clinical Presentation

Signs and Symptoms

  • Decreased vision
  • Floaters
  • Maybe preceded by episodes of Amaurosis Fugax.

Fundus Examination

  • Superficial and deep hemorrhages in all four quadrants of the retina ("Tomato splash Appearance", "Blood and thunder Appearance" or "Battlefield Appearance")
  • Venous dilation and tortuosity
  • Cotton wool spots
  • Macular edema
  • Retinal detachment
  • Vitreous hemorrhage
  • Neovascular glaucoma

Differential Diagnosis

  • Central retinal artery occlusion (major differential)
  • Diabetic retinopathy
  • Optic neuritis
  • Vitreous hemorrhage
  • Ischemic optic neuropathy
  • Retinal vasculitis
  • Viral retinitis
  • Ocular ischemic syndrome
  • Sickle cell retinopathy
  • Juxta foveal telangiectasia

Investigations

Fundus Fluorescein Angiography

  • Normal filling of retinal and choroidal arteries
  • Delayed filling of retinal veins
  • Variable staining of the retinal veins
  • Variable retinal vascular leakage resulting in retinal edema

Optical Coherence Tomography

  • For Diagnosis and follow up of Macular edema which is an important treatable complication of CRVO
  • Cystic fluid filled spaces in the macula
  • Thickening of the retina
  • Submacular fluid

Electroretinography

  • Reduction in b wave (positive deflection in ERG)
  • Reduction in b/a ratio (ratio of positive deflection to initial negative deflection in ERG)

Color Doppler Imaging

  • To detect the onset of neovascularisation

Investigations to check for systemic diseases

  • Blood pressure monitoring
  • Hemoglobin A1C, BUN and Serum creatinine levels to check for diabetic control
  • Lipid profile
  • ESR and CRP to look for systemic inflammation
  • Blood coagulation studies including PT, aPTT and INR
  • Serum homocystein levels
  • ANA, Anti-dsDNA and other autoantibodies test to check for autoimmune etiology
  • Measurement of intraocular pressure to look for glaucoma

Management

Management specific for CRVO

  • Systemic anticoagulation
  • Antiplatelet agents
  • IV thrombolysis is used only if there is another known condition present e.g. antiphospholipid antibody syndrome
  • In cases where IV thrombolysis needs to be considered, it must be done within 4.5 hours of the onset of symptoms and after obtaining a head CT.
  • Surgical management includes vitrectomy with sheathotomy or radial optic neurotomy
  • Surgical options are not considered commonly as there is no great data to support their use

Management of complications

  • For symptomatic macular edema, intra-vitreal Anti-VEGF inhibitors are the first line and intra-vitreal glucocorticoids or retinal laser photocoagulation are the second line.
  • To deal with neovascular complications, retinal laser photocoagulation is used.

Referral to ophthalmologist

  • If neurologists suspect this condition then immediate referral to an ophthalmologist must be made
  • It is preferable to not dilate the eyes prior to an ophthalmologist's evaluation because they need to test relative afferent pupillary defect, which is an important prognostic marker of CRVO.
  • The neurologist should do their own comprehensive exam (for painless visual loss and neurologic exam)
  • The visual exam should include pupillary response, visual acuity, confrontational visual fields and extra-ocular movements.
  • The neurologic exam should be aimed to rule out other accompaniments of multiple sclerosis.

Follow-up of patients

  • Monthly exams should be done for at least 6 months if the patient has severe vision loss (visual acuity 20/400 or less). Follow up should continue beyond 6 months if complications develop.
  • In cases where vision loss is not severe (visual acuity better than 20/400), routine exams may be done every few months until visual acuity stabilizes

Expected prognosis

  • BRVO is better for visual acuity with almost 1/3rd having long-term acuity at 20/40 or higher.
  • CRVO is worse and prognosis depends upon the initial visual acuity. (For 20/50-20/200, 1/3rd will progress to worst acuity than 20/200, for less than 20/200, only 20% had visual acuity that improved).

Conclusion

  • Central retinal vein occlusion needs to be managed with a multidisciplinary approach involving neurologists and ophthalmologists.
  • The neurologist's responsibility is to acutely manage the patient and to evaluate whether any pertinent neurologic disorders may need to be considered
  • Evaluation for multiple-sclerosis, severe intracranial vascular stenosis, systemic autoimmune syndromes such as lupus or antiphospholipid antibody syndrome should be done.
  • The neurologist should retain a closed-loop communication with the ophthalmologist during that time.
  • If the diagnosis of CRVO is confirmed with fluorescein angiography, the neurologist may feel comfortable in discharging patient from their care.
 

Further Reading

  • Prisco D, Marcucci R. Retinal vein thrombosis: risk factors, pathogenesis and therapeutic approach. Pathophysiology of Haemostasis and Thrombosis. 2002 Sep-Dec;32(5-6):308-311. DOI: 10.1159/000073587. PMID: 13679663.
  • Williamson TH. Central retinal vein occlusion: what's the story?. Br J Ophthalmol. 1997;81(8):698-704. doi:10.1136/bjo.81.8.698

Bibliography

  • Bhagat N, Goldberg MF, Gascon P, Bell W, Haberman J, Zarbin MA. Central retinal vein occlusion: review of management. Eur J Ophthalmol. 1999;9(3):165-180. doi:10.1177/112067219900900304
  • Hayreh SS. Classification of central retinal vein occlusion. Ophthalmology. 1983;90(5):458-474. doi:10.1016/s0161-6420(83)34530-9
  • Prisco D, Marcucci R, Bertini L, Gori AM. Cardiovascular and thrombophilic risk factors for central retinal vein occlusion. Eur J Intern Med. 2002;13(3):163-169. doi:10.1016/s0953-6205(02)00025-0
  • Prisco D, Marcucci R. Retinal vein thrombosis: risk factors, pathogenesis and therapeutic approach. Pathophysiology of Haemostasis and Thrombosis. 2002 Sep-Dec;32(5-6):308-311. DOI: 10.1159/000073587. PMID: 13679663.
  • Quinlan PM, Elman MJ, Bhatt AK, Mardesich P, Enger C. The natural course of central retinal vein occlusion. Am J Ophthalmol. 1990;110(2):118-123. doi:10.1016/s0002-9394(14)76979-x
  • Rogers S, McIntosh RL, Cheung N, Lim L, Wang JJ, Mitchell P, et al. The prevalence of retinal vein occlusion: pooled data from population studies from the United States, Europe, Asia, and Australia. Ophthalmology. 2010
  • Thapa, R., Bajimaya, S., Paudyal, G. et al. Prevalence, pattern and risk factors of retinal vein occlusion in an elderly population in Nepal: the Bhaktapur retina study. BMC Ophthalmol 17, 162 (2017). https://doi.org/10.1186/s12886-017-0552-x
  • Tomasini DN, Segu B. Systemic considerations in bilateral central retinal vein occlusion. Optometry. 2007;78(8):402-408. doi:10.1016/j.optm.2006.12.017
  • Williamson TH. Central retinal vein occlusion: what's the story?. Br J Ophthalmol. 1997;81(8):698-704. doi:10.1136/bjo.81.8.698