"Your eyes witness the wonders." It is pretty necessary to take proper care and go for frequent eye checkups so as to detect any vision abnormlities or severe illness affecting the eyes. Neovascularization causes vision irregularity and abnormality. Neovascularization is nothing but the irregular or abnormal development of very small and leaky blood vessels inside the eye. Neovascularization condition causes abnormal growth of blood vessels inside eye. Today Neovascluarization and its treatment have been studied greatly by many doctors and scientists from all over the world. Neovascularization is a genetic disorder associated with increased enzyme and growth factor promoting vascular endothelial growth.1
This current article is all about understanding Neovascularization, its types, complications, diagnosis and treatment.
Introduction On Ocular Neovascularization:
The formation of anomalous, tiny and leaky fragile blood vessels within the eye is a condition termed as Neovascularization. The vision abnormality follows because of anomalous blood vessel growth inside the eye. The abnormal blood vessels obstructs the pathway of the vision resulting in vision deformity. The neovascular blood vessels are fragile blood vessels because of weak vascular walls and often bleeds. The intraoptical bleeding and enlarged blood vessels inside the eye interferes in the normal function of the eye.
Based on the location of their growth; Neovascularization is primarily divided into Corneal Neovascularization, Corodial neovascularization, Retinal neovascularization, Rubiosis Iridis or the Neovascularization in Iris. The following array of the article will discuss about these types of neovascularization in detail. But prior to that let us also study about the complications which can take place with Neovascularization.
Complications Due To Neovascularization In Eye:
Here below are some of the most crucial complications occurring due to Neovascularization in eye.
- Vetreous Hemorrage- This is the complicated condition caused due to the excessive bleeding from Neovascularization blood vessels in to the central cavity of the eye.
- Neovascular Glaucoma- With the growth of neovascular blood vessels on the structures like Iris or the angel lying at the front of the eye; there exists an impairment in the natural pressure relieving mechanisms of the eye.
It must be noted that though such complications along with the neovascularisation can be problematic; but regular or frequent checkups of eye can assist you in preventing any such kind of issues due to Neovascularization.
Types Of Ocular Neovascularization:
Now comes the section which deals with the list of some of the major types of Neovascularization.
- Corodial Neovascularization: Loss of vision without any noted pain is accompanied by Corodial Neovascularisation. Such a condition exists when there is an abnormal growth of blood vessels in the Coriocapillaries and then pass through the Bruch's membrane and proliferate the retinal pigment epithelium or under the retina.2It is termed as Type 1 when it proliferates the retinal pigment epithelium; while when it affects under the retina, it is termed as Type-2. Such condition of Corodial neovascularisation is primarily due to the exudative age-related macular degeneration and also may lead to severe disorders including cordial rupture, pathological myopia, chorioretinal scars, and birdshot.
- Black spots in the vision, most noted in the central vision
- Distorted or irregular vision
- Colors and object size usually do not look the same for each eye.
- Flashing lights in the central vision.
- Corneal Neovascularization: This is the type of Neovascularization which occur when there is excessive or abnormal growth of blood vessels from the limbal vascular flexus in to the cornea.3This is mainly caused with the deprivation of oxygen from the air. The prime cause is the use of contact lens, especially the hydrogel lenses which are made of HEMA and have low oxygen transmissibility in to the cornea and thus leads to oxygen deprivation inside cornea leading to Corneal Neovascularisation.
- Irritation in eye and dryness
- Existence of Conjunctivitis or Pink eye symptoms
- Usually there are no great notable symptoms.
- Rubeosis Iridis: The abnormal formation of blood vessels on the Iris is termed as Rubeosis Iridis or Iris Neovascularization.4, 5The prime issue related to Rubeosis Iridis is the disease process which is linked with retina where it lacks enough supply of oxygen (Retinal ischemia) and thus leads to further complications including Neovascular Glaucoma. Usually in such case of retinal ischemia; there occurs formation of new blood vessels with the VEGF factors released from the ischemic retina. Usually it is caused by diabetic retinopathy, central retinal vein occlusion, carotid arterial disease, long standing retinal detachment etc.
- Though not visible to the naked eye, the symptoms usually start with blurred vision, especially in the central and peripheral region.
- Leading to glaucoma and its irritating symptoms
- Loss of vision is noted in some cases.
- Retinal Neovascularization: Iris neovascularisation is usually associated with a kind of disease process on the retinal surface termed as Retinal Neovascularisation or the vascularisation of ischemic tissues in retina leading to the lack of a bifurcating pattern of normal blood vessels. Retinal vein occlusion and diabetes are most common causes leading to Retinal Neovascularisation.6
- Loss of vision.
- Blurring of central and peripheral vision
- Leads to Neovascular Glaucoma which is characterized by irritation, redness and pain in eye.
Diagnosis Of Ocular Neovascularization:
"If you can make the diagnosis, the treatment is easy and the damage can be reversed. But the diagnosis is tricky." This wonderful saying from Ralph Green suggests all about how important diagnosis is. So, before speaking about the treatment procedure for Neovascularization, let us first talk about the diagnosis and detection of neovascularization or complications related to the conditions.
Diagnosis And Detection:
The intial eye examination suggesting increased intraocular (inside the eyball) pressure often follows further check up of retina and inner globe of the eye. Neovasculazation is diagnosed by ophthalmoscopic eye examination. Neovascularization is diagnosed when examiner finds the abnormal growth of the blood vessels and bleeding inside the eye mostly localized in posterior chamber of the eyeball. The cause of neovascular glaucoma is evaluated by blood examination and doppler study of carotid artery. As discussed before, diabetes, central retinal vein occlusion and carotid artery obstructive diseases are some of the health conditions which are known to be linked with neovascularization glaucoma. Neovascular glaucoma is diagnosed when abnormal eye examination is associated with these systemic diseases.
Early detection of the neovascular condition is essential to prevent complications linked with it. Early detection of neovascularization is possible when patient is frequently seen by ophthalmologist. The complaints like dizziness and blurring vision should be evaluated by eye examination and carotid artery study to evaluate carotid artery obstructive disease. A comprehensive ocular examination follows if patient is suffering with diabetic retinopathy or carotid artery obstruction. Some of the advanced eye examination includes nondilated gonioscopy, electroretinography and pupillary reactions.
Treatment Procedures For Ocular Neovascularization:
Let us now study on some of the most crucial treatment procedures involved in treating neovascularization.
- Medications- Anti-inflammatory drugs, MMP-inhibitors and the Anti-VEGF agents can be used to treat corneal neovascularization. Anti-VEGF medications and injections are also effective in other types of neovascularizations like the Iris Neovascularization or Rubiosis Iridis.
- Photodynamic Therapy (PT)- PT is also known to be a treatment method in corneal neovascularization. However this is very expensive.
- Corneal Transplant- Corneal transplant is a surgical procedure which is performed when conservative treatment is ineffective. Corneal transplant is one of the most effective treatments for corneal neovascularization.
- Contact Lenses- Modern rigid gas permeable and silicon hydrogel contact lens are more effective in preventing corneal neovascularization in patients using contact lenses.
- Photocoagulation- Most common and primary tool for treating neovascularization, especially the rubiosis Iridis is Panretinal Photocoagulation. Photocoagulation is a laser treatment, which involves a laser beam creating plenty of laser scars at the corner of the retina. These laser scars are known to reduce or prohibits the effect of the growth factors like VEGF, which are known to produce new blood vessels in an abnormal manner. It must be noted the Panretinal Photocoagulation or PRP can be done by three ways including the Slit lamp delivery system, indirect laser or by endolaser during the time of vitrectomy.
1. Vascular endothelial growth factor and its soluble receptors-1 and -2 in iris neovascularization and neovascular glaucoma.
Noma H1, Mimura T, Yasuda K, Shimura M.
2. Intraocular neovascularization associated with choroidal ganglioneuroma in neurofibromatosis type 1.
Ishijima K1, Kase S, Noda M, Ishida S.
Eur J Ophthalmol. 2011 Nov-Dec;21(6):837-40.
3. Contribution of Corneal Neovascularization to Dendritic Cell Migration into the Central Area during Human Corneal Infection.
Narumi M1, Kashiwagi Y2, Namba H1, Ohe R3, Yamakawa M3, Yamashita H1.
PLoS One. 2014 Oct 9;9(10):e109859.
4. Iris neovascularization and neovascular glaucoma in neurofibromatosis type 1: report of 3 cases in children.
Al Freihi SH1, Edward DP, Nowilaty SR, Abouammoh MA, Morales J.
J Glaucoma. 2013 Apr-May;22(4):336-41.
5. Bilateral rubeosis iridis and rubeotic glaucoma due to peripheral occlusive vasculitis associated with multiple sclerosis.
Turner SJ1, Dharmasena A, Deane J.
Ocul Immunol Inflamm. 2011 Oct;19(5):373-5.
6. Neovascular glaucoma.
Folia Med (Plovdiv). 2005;47(2):5-11.