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Neovascularization of the Iris (Rubeosis Iridis)

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Title: Neovascularization of the Iris (Rubeosis Iridis)
Author (s): Kathryn Lewis, MSIV University of California, Riverside School of Medicine
Photographer: James Gilman, CRA, FOPS
Date: July 13, 2019
Keywords/Main Subjects: neovascularization of the iris, rubeosis iridis, neovascular glaucoma

 

Image 1. Prominent temporal neovascularization of the iris and angle, which extends nasally.

 

Image 2. Neovascularization of the iris with capillaries at the pupillary margin. Notable chemosis and conjunctival injection.

 

Overview: Neovascularization of the iris (NVI), known as rubeosis iridis, is defined as blood vessel proliferation along the surface of the iris. There are many causes of NVI, including most commonly diabetic retinopathy (DR) and central retinal venous occlusion (CRVO). Untreated, it can result in neovascular glaucoma, which is often difficult to treat and vision threatening.  

Pathophysiology: The pathophysiology of NVI is complex, involving dysregulation of pro- and anti-angiogenic factors in the setting of posterior segment ischemia. Other causes of NVI, such as intraocular tumors or anterior chamber ischemia, also result in factor dysregulation.1 Imbalance of vascular endothelial growth factor (VEGF), interleukin-6 (IL6), and pigment epithelium-derived factor (PEDF) results in proliferation of friable capillaries.1 These vessels grow along the surface of the iris, first visible at the pupillary margin, and can extend to the iridocorneal angle.

Presentation & Diagnosis: NVI is initially painless and asymptomatic. In early stages, a fine network of capillaries is visible at the pupillary margin on slit lamp examination (Image 2, 3). Capillaries then extend to the iridocorneal angle, known as neovascularization of the angle (NVA), appreciable on gonioscopy. When suspicion for NVI is high but not seen on slit lamp, iris fluorescein angiography can be performed to further elucidate the presence of NVI in a patient.

Differential Diagnosis: The differential diagnosis includes four main etiologies: retinal ischemia, retinal detachment, tumors, and ocular inflammation. Table 1 further elucidates examples of diseases that cause NVI.2 The most common etiology is retinal ischemia due to DR or CRVO.

 

Table 1. Differential Diagnosis of NVI

Retinal Ischemia Tumors Ocular Inflammation Retinal Detachment
Diabetic Retinopathy

 

Central Retinal Vein Occlusion

 

Central Retinal Artery Occlusion

 

Sickle Cell retinopathy

 

Carotid artery occlusion

 

Retinopathy of prematurity

 

Melanoma (iris/choroid)

 

Metastatic cancer

 

Retinoblastoma

Endophthalmitis

 

Chronic uveitis

 

Anterior chamber

ischemia

Retinoschisis

 

Coat’s disease

              CRAO = central retinal artery occlusion

 

Prognosis and Complications: Untreated, NVI can progress to neovascular glaucoma (NVG), a form of secondary glaucoma. There are four stages involved in this process: prerubeosis, rubeosis, open angle glaucoma, and lastly closed angle glaucoma (Table 2).3 The time from NVI to developing NVG varies. Following CRVO, NVG can develop within 1 to 6 months, while it takes at least 1 year in diabetic patients.2 As NVI progresses to NVA, the vessels impair aqueous humor outflow, resulting in open angle glaucoma. As fibrotic membranes develop and contract, the iridocorneal angle closes, resulting in closed angle glaucoma. In untreated cases, NVG will cause blindness and pain, often ending in enucleation.

 

Table 2. Stages of NVG

Prerubeosis –> Rubeosis –> Open angle  –> glaucoma Closed angle glaucoma
Symptoms None None None Eye pain, nausea, vomiting, headaches, visual loss
Slit Lamp Findings None NVI NVI, NVA, fibrosis, hyphema NVI, NVA, fibrosis, corneal edema, hyphema
IOP Normal Normal Elevated Elevated

 

Treatment: The gold standard treatment of NVI is pan retinal photocoagulation (PRP) to reduce neovascularization. PRP can also be used if patients progress to NVG. In recent years, intravitreal bevacizumab (IVB), an anti-VEGF agent, has proven to be effective for shortterm management at reducing neovascularization at the iris and angle and controlling IOP.2 Once NVG has developed, treatment is often complicated. For example, in later stages of NVG, topical agents that work on aqueous flow tend not to improve IOP. Surgery, such as trabeculectomy, can be complicated by intraoperative hemorrhage from friable vessels and excessive post-surgical scarring.4

References:

  1. Wang JW, et al. Short-term effect of intravitreal ranibizumab on intraocular concentrations of vascular endothelial growth factor-A and pigment epithelium-derived factor in neovascular glaucoma. Clinical and Experimental Ophthalmology 2015;43:415-421. Doi: 10.1111/ceo.12477
  2. Rodrigues GB, et al. Neovascular glaucoma: a review. International Journal of Retina and Vitreous 2016;2:26. https://doi.org/10.1186/s40942-016-0051-x
  3. Shazly TA, Latina MA. Neovascular glaucoma: etiology, diagnosis and prognosis. Semin Ophthalmol2009;24(2):113-121. DOI: 10.1080/08820530902800801
  4. Shen C, Aref AA, Salim S. Neovascular Glaucoma. American Academy of Ophthalmology EyeWiki. https://eyewiki.aao.org/Neovascular_Glaucoma (accessed 10 Jul 2019).

Faculty Approval by: Griffin Jardine, MD

Identifier: Moran_CORE_26882

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