Rubeosis iridis

Rubeosis iridis is a medical condition of the iris of the eye in which new abnormal blood vessels (i.e. neovascularization) are found on the surface of the iris. It is usually associated with disease processes in the retina, which involve the retina becoming starved of oxygen (ischaemic). The ischemic retina releases a variety of factors, the most important of which is VEGF. These factors stimulate the formation of new blood vessels (angiogenesis). Unfortunately, these new vessels do not have the same characteristics as the blood vessels originally formed in the eye. In addition, new blood vessels can form in areas that do not have them. Specifically, new blood vessels can be observed on the iris. In addition to the blood vessels in the iris, they can grow into the angle of the eye. These blood vessels then block fluid leaving the eye and result in an increase in intraocular pressure. This is called neovascular glaucoma.

If caught early, the neovascularization can be reversed with prompt pan retinal photocoagulation (PRP), or injection of anti-VEGF medications with subsequent PRP. The injection blocks the direct effect of VEGF and acts more quickly but will wear off in about 6 weeks. [Davidorf FH, Mouser JG, Derick RJ. "Rapid improvement of rubeosis iridis from a single bevacizumab (Avastin) injection." "Retina." 2006 Mar;26(3):354-6. PMID 16508439.] PRP has a slower onset of action but can last permanentely (if sufficient is given). Once the neovascularization has been longstanding, the new vessels recruit fibrous tissue, and as this forms and contract, the angle can be permanently damaged, and will not respond to treatment. If this occurs, then surgical intervention is required to reduce the pressure (such as a glaucoma drainage implant)

This condition is often associated with diabetes in advanced proliferative diabetic retinopathy. Other conditions causing rubeosis iridis include central retinal vein occlusion [Laatikainen L, Blach RK. "Behaviour of the iris vasculature in central retinal vein occlusion: a fluorescein angiographic study of the vascular response of the retina and the iris." "Br J Ophthalmol." 1977 Apr;61(4):272-7. PMID 857872.] , ocular ischemic syndrome [Dhooge M, de Laey JJ. "The ocular ischemic syndrome." "Bull Soc Belge Ophtalmol." 1989;231:1-13. PMID 2488440.] , and chronic retinal detachment.

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