Contents
Retinal vascular disease, resulting in potentially irreversible loss of vision due to obstruction of normal venous system of the retina.
- #2 M/C retinal vascular disease (after diabetic retinopathy)
Etiology
Major risk factors:
Retinal vein occlusion (RVO) is a disease of the old population (age >50 years old)
- Hypertension
- Diabetes
- Atherosclerosis
Other risk factors:
- Glaucoma (M/C local factor predisposing to RVO as increased intraocular pressure compromises retinal vein outflow and produces stasis)
- Syphilis, sarcoidosis
- Vasculitis
- Increased intraorbital/intraocular pressure
- Hyphema
- Hyperviscosity syndromes (multiple myeloma, Waldenstrom’s macroglobulinemia, and leukemia)
- High homocysteine levels
- Sickle cell
- HIV
Classification
Anatomical classification:
Depending on the area of retinal venous drainage effectively occluded
- Central retinal vein occlusion (CRVO) (less common, more severe)
- Branch retinal vein occlusion (BRVO) (more common)
Functional classification:
Subtyping based on the degree of capillary non-perfusion on fluorescein angiography with each having distinct clinical features and prognosis.
- Nonischemic “perfused” CRVO/HRVO (M/C, 70% cases)
- Characterized by vision that is better than 20/200, 16% progress to nonperfused; 50% resolve completely without treatment; defined as <10 disk diameter (DD) of capillary nonperfusion.
- Ischemic “perfused” CRVO/HRVO
- Defined as more than 10 DD of nonperfusion; patients are usually older and have worse vision; 60% develop iris NV; up to 33% develop neovascular glaucoma; 10% are combined with branch retinal arterial occlusion (usually cilioretinal artery due to low perfusion pressure of choroidal system)
Pathophysiology
Three main factors contribute to thrombosis: venous stasis, endothelial damage, and hypercoagulability
Thrombosis within a retinal vein as described earlier will lead to a partial obstruction of blood flow within the vein and from the eye. The subsequent increased intraluminal pressure, if sufficiently high, will cause transudation of blood products into the retina according to Starling’s law. This will result in increased interstitial (retinal) fluid and protein. The latter will increase the interstitial oncotic pressure, perpetuating tissue edema, which will impede capillary perfusion and lead to ischemia.
Venous occlusion induces an ischemic and hypoxic state that leads to visually significant sequelae including macular edema and anterior segment and retinal neovascularization.
Clinical features
Variable painless visual loss with a combination of fundal findings.
Fundal findings:
- Retinal vascular tortuosity
- Retinal hemorrhages (blot and flame shaped)
- Cotton wool spots
- Optic disc swelling
- Macular edema
Vision loss:
Visual loss after CRVO commonly occurs as a result of the following
- Macular edema
- Macular ischemia
- Advanced stages:
- Vitreous hemorrhage
- Neovascularization (develops in 2⁄3 cases of ischemic RVO)
Diagnosis
Fundus examination:
- CRVO: Splashed sauce appearance
- BRVO: Flame-shaped haemorrhages
Fluorescein angiogram:
- Blocked venous fluorescence from retinal hemorrhages
- Capillary non-perfusion
- Vessel wall staining
Differential diagnosis:
- Ocular ischemic syndrome
- Proliferative diabetic retinopathy
- Hyperviscosity retinopathy
- Branch retinal vein occlusion
Management
Anti-vascular endothelial growth factors (anti-VEGF):
First-line treatment
- Ranibizumab
- Bevacizumab
- Aflibercept
Intravitreal corticosteroids:
Second line drug in resistant cases or as an adjunct from the start.
- Dexamethasone implants
- Triamcinolone acetonide
Laser therapy:
- GRID photocoagulation: reduce macular edema and improve VA
- Scatter PRP: Reduce VEGF load by ablating peripheral ischemic retina.