NEOVASCULAR GLAUCOMA: A BRIEF REVIEW
Introduction
Neovascular glaucoma (NVG) is a secondary glaucoma characterized by the growth of abnormal new blood vessels on the iris and the angle of the anterior chamber. This condition typically results from ischemic retinal diseases; in order to understand better the percentage of its etiologies, do not forget the rule of 33; see most commonly proliferative diabetic retinopathy (33%) and central retinal vein occlusion (CRVO) (33%) after this two ones, the third most common cause is ocular ischemic syndrome in 13% ¹. The pathophysiology of NVG involves the release of angiogenic factors, such as vascular endothelial growth factor (VEGF), which stimulate neovascularization².
Classification³⁻⁴
NVG can be classified into three stages based on the progression of neovascularization and its effects on intraocular pressure (IOP):
1. Pre-glaucomatous Stage: Characterized by neovascularization of the iris (NVI) without a significant increase in IOP. Patients may be asymptomatic during this stage or experience mild symptoms such as slight eye discomfort or visual disturbances.
2. Open-Angle Stage: Neovascularization extends to the angle of the anterior chamber (NVA), "overlying the trabeculum," but the angle remains open (see figures). Due to impaired aqueous outflow, IOP increases. Symptoms may include eye pain, redness, and decreased vision.
3. Closed-Angle Stage: The fibrovascular membranes contract, leading to synechial angle closure and a significant increase in IOP. This stage is associated with severe pain and significant vision loss and can rapidly lead to optic nerve damage and blindness if not promptly treated.
Clinical Presentation
The clinical presentation of NVG often includes symptoms such as eye pain, redness, decreased vision, and elevated IOP. On examination, neovascularization of the iris (NVI) or the angle (NVA) can be observed. Some other findings may be related to the causative condition, such as proliferative diabetic retinopathy or CRVO. If the fundoscopy is not viable, a mode B-US is recommended to rule out any other probable causes, especially if the patient's medical history does not include systemic conditions such as diabetes or hypertension⁵.
Management
NVG management focuses on lowering IOP and addressing the underlying ischemic condition. Topical hypotensive drops such as timolol, brimonidine, and dorzolamide two times a day are advisable. Prostaglandin analogs can increase inflammation but are still often used. Antiinflammatory drops such as prednisolone are advisable, and some cycloplegic agents such as atropine may help in the initial state. Sometimes, you can add systemic management based on the individual circumstances, including acetazolamide 250 mg 3 times daily. Always check or verify if the patient does not have renal impairment. Anti-VEGF injections should also be considered as the pack of the initial treatment to reduce neovascularization. Panretinal photocoagulation (PRP) is also commonly employed to treat ischemic retinal conditions and reduce the stimulus for new vessel growth in combination with anti-VEGF injections. Sometimes, the media is opaque, the cornea has edema, or the patient has a vitreous hemorrhage that hampers the visibility at the posterior pole, so starting with PRP will not always be possible. In advanced cases, surgical intervention, such as aqueous shunt devices, may be necessary to control IOP. It is crucial to emphasize the systemic control of the underlying condition since it drastically influences the response and sustainability of the initial treatment ⁵.
Prognosis
Despite aggressive treatment, NVG often has a poor prognosis due to its rapid progression and the difficulty in controlling IOP and preventing optic nerve damage. Early detection and prompt intervention are crucial for improving outcomes in patients with this challenging condition.
References
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Senthil S, Dada T, Das T, Kaushik S, Puthuran GV, Philip R, Rani PK, Rao H, Singla S, Vijaya L. Neovascular glaucoma - A review. Indian J Ophthalmol. 2021 Mar;69(3):525–534. [PMC free article] [PubMed]
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Rodrigues GB, Abe RY, Zangalli C, Sodre SL, Donini FA, Costa DC, Leite A, Felix JP, Torigoe M, Diniz-Filho A, de Almeida HG. Neovascular glaucoma: a review. Int J Retina Vitreous. 2016;2:26. [PMC free article] [PubMed]
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Shazly TA, Latina MA. Neovascular glaucoma: etiology, diagnosis, and prognosis. Semin Ophthalmol. 2009 Mar-Apr;24(2):113-21. doi: 10.1080/08820530902800801. PMID: 19373696.
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Mishra C, Meyer JJ. Neovascular Glaucoma. (2022). Nov 7. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan–. PMID: 35015418.