Ophthalmology spot diagnosis : Rubeosis Iridis

Definition: Neovascularization of iris

Pathophysiology: Causes that lead to retinal hypoxia triggers release of vasoproliferative factors include vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and others

Etiology:

1. Diabetic Retinopathy

2. Retinal Vascular Occlusive Diseases

Central Retinal Vein Occlusion (CRVO)
Ischaemic Hemiretinal Vein Occlusion

3. Ocular Ischaemic Syndrome

Carotid Artery Occlusive Disease
Takayasu’s Syndrome
Carotid-Cavernous Fistula
Giant Cell Arteritis
Wyburn-Mason syndrome
Strabismus Surgery
Ocular Radiation

4. Tumours

Uveal Melanomas
Metastatic Choroidal Tumours
Medulloepithelioma
Hypoxic Retinoblastoma
Pigmented Ciliary Adenocarcinoma
Metastatic Malignant Lymphoma

5. Others

Uveitis
Retinal Vasculitis
Coat’s Disease (Retinal telangiectasia)
Eales’ Disease (Periphlebitis retinae)
Sarcoidosis
X-linked Retinoschisis
Chronic Retinal Detachment
Retinopathy of Prematurity (ROP)
Systemic Cryoglobulinaemia

Important causes:

Proliferative Diabetic Retinopathy (PDR)

Central Retinal Vein Occlusion (CRVO)

Sickle cell retinopathy

Chronic iridocyclitis

Retinoblastoma

Grading of rubeosis iridis:

0 : No iris neovascularization
1 : Less than 2 quadrants of NV at iris pupillary zone
2 : More than 2 quadrants of NV at iris pupillary zone
3 : Grade 2 + less than 3 quadrants of NV at iris ciliary zone and/or ectropion uveae
4 : More than 3 quadrants of NV at iris ciliary zone and/or ectropion uveae

Findings:

Abnormal iris vessels
Perform gonioscopy to assess presence of angle neovascularization
May have elevated IOP (neovascular glaucoma)

Rubeosis Iridis and Neovascular glaucoma:

The disease develops in 3 stages:

1. Neovascularization of the iris (NVI)

2. Secondary open angle glaucoma (SOAG): The NVI extend to involve the angle, and are accompanied by fibrosis, blocking the trabecular meshwork and causing ocular hypertension, and SOAG.

3. Secondary angle closure glaucoma (SACG): Myofibroblasts within the fibrovascular tissue proliferate and contract, forming peripheral anterior synechiae (PAS), and secondary angle closure, with resulting intra-ocular pressure rise.