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:

1. Proliferative Diabetic Retinopathy (PDR)
2. Central Retinal Vein Occlusion (CRVO)
3. Sickle cell retinopathy
4. Chronic iridocyclitis
5. 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:

1. Abnormal iris vessels
2. Perform gonioscopy to assess presence of angle neovascularization
3. 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.

100 days glaucoma: Neovascular glaucoma (NVG) secondary to ischemic CRVO

Treatment:

1. Ischemia: Panretinal Photocoagulation (PRP)
2. IOP control: Glaucoma drainage implant (e.g. Molteno’s tube)