Disease caused by increased intraocular (inside eyeball) pressure is known as glaucoma. Early diagnosis of neovascular glaucoma depends on frequent checking of the eye pressure during routine eye examination. Neovascular glaucoma (NVG) is a form of secondary glaucoma, which is actually very much a serious condition resulting in ischemic retina. Increased intraocular pressure in presence of neovasculization is known as neovascular glaucoma. Glaucoma is divided as open and closed angle glaucoma. The angle is the area between iris and cornea. Fluid of the eye chamber passes through the trabecular network around the angle and base of cornea. When the angle is closed and fluid is unable to escape through the trabecular network the closed angle glaucoma develops. Similarly slow scarring or neovascularization causes closing of trabecular network resulting in open angle glaucoma. Open angle glaucoma progresses slowly.
Neovascularization of anterior segment involves iris and forms a fibrovascular membrane. The membrane obstructs trabeculous network resulting in open angle neovascular glaucoma. Neovascular glaucoma often does not respond to medication and may need surgical treatment. Delayed diagnosis causes persistent increase of intraocular pressure and retinal ischemia resulting in partial or total blindness. Though there are various treatment procedures and medical therapies prescribed for Neovascularization and Neovascularization Glaucoma; it must be noted that treating NVG has always remained a challenge. It is better if the condition is diagnosed before the progression of neovascular glaucoma and treated accordingly. A proper management and control will help to prevent from the devastating outcomes of NVG. So help you and your dear ones get treated earlier and prevent loss of vision.
- Increased intraocular pressure (ocular hypertension) over 30 mm Hg.
- Progressive visual field loss
- Visual deformity like seeing halos around eyes
- Fixed dilated pupil
- Dilated Conjunctival blood vessels at the corneal edge
- Hazy cornea.
Investigations For Neovascular Glaucoma
- Tonometry- Tonometry measures intraocular pressure, which is high and often over 30 mm Hg.
- Gonioscopy- Gonioscopy is performed to examine the anterior angle of the anterior chamber. The gonioscopy is performed to diagnose neovascularization.
- Ophthalmoscopy Examination- The examination is performed to observe the optic nerve, retina and posterior chamber.
- Visual Field Test- The test is performed to evaluate visual field loss.
- Optical Coherence Tomography- The test is performed to examine high resolution images of the anterior segment. Test helps to diagnose glaucoma and abnormality of retina.
- Scanning Laser Polarimetry- The test involves use of polarized light to examine eye and retinal nerve. Abnormal retinal nerve in presence of increased intraocular pressure suggests neovascular glaucoma.
- Scanning Laser Ophthalmoscopy- Laser scanning microscopy study of retina and cornea helps to diagnose glaucoma and retinal disorder.
Blood Glucose Level- Blood sugar is often high. One third of the patients suffering with of neovascular glaucoma are also suffering with diabetes and diabetic retinopathy.
- Carotid Artery Doppler Study- Neovascular glaucoma is associated with carotid artery obstructive disease.1 Doppler study assists in diagnosis of carotid artery partial or total obstruction.
Treatment Of Neovascular Glaucoma
It must be noted that treatment of NVG is difficult and response to conservative treatment often results in failure to decrease eye pressure. However early diagnosis of the condition can help to preserve loss of vision due to neovascular glaucoma. Here below we are going to present some of the treatments available for neovascular glaucoma as per its progressive stages.
Prophylactic treatment is conducted before the complications of NVG is established. The treatment becomes difficult once Neovascular Glaucoma symptoms are predominant in later stage. The treatment procedures like the Panretinal photocoagulation, or other treatments prescribed for treating the pre-NVG conditions are included under the prophylactive treatments.
Early Stage Treatment For Neovascular Glaucoma:
Early stage of Neovascular Glaucoma is characterized by the growth of fibrovascular membrane in some or all of the angle and in turn obstructing the trabecular meshwork and an elevated level of IOP.
- Topical Atropine- Topical atropine 1% for reducing the ocular congestion.
- Topical Steroids- Topical steroids are prescribed for reducing inflammation.
- Antiglauoma Medications- Secondary open angle glaucoma treated with the osmotic agents like carbonic anhydrase inhibitors.
- Oral Glycerol and Intravenous Mannitol- The glycerol and mannitol is prescribed during early stages and following surgery to treat neovascular glaucoma.
- Photodynamic Therapy- It has also been reported that the photodynamic therapy with verteporfin directed at the iris and at the angle to obliterate neovascularization and to lower the IOP; has been a successful means of treating early stage Neovascular Galucoma or NVG.2
- Panretinal Photocoagulation- This treatment is advised for anterior segment open angle neovascular glaucoma.3 Procedure is effective when performed in earlier stages.
Advanced Stage Treatment For Neovascular Glaucoma:
The advanced stage in the progression of Neovascular Galucoma or NVG is characterized by synechial closure of the angle and the approach of secondary angle closure glaucoma. This is the stage which requires crucial and highly effective treatment so as to protect any further angle closure and also to make the eye prepared for surgical intervention required for useful vision. Medical therapy is also included in the treatment methods and is conducted with the use of topical atropine and topical steroids. Anti glaucoma medications and certain carbonic anhydrase inhibitors are recommended for treating advance stage of NVG. Following surgical treatment are advised for neovascular glaucoma not responding to conservative treatment.
- Aqueous drainage implants
- Cyclodestruction using Nd Yag or Diode laser
- Alcohol injection/enucleation.
Anti- VEGF Therapy:
Anti-Vascular endothelial growth factor(Anti VEGF) has been considered one of the most effective treatment for neovascularization.
- A combination of Anti-VEGF and Panretinal photocoagulation in NVG conditions help you fight against the dangers of neovascular glaucoma or loss of vision.
- Among all the anti- VEGF adjunct treatments prescribed for NVG, the Intravitreal bevacizumab is the most frequent and common form of treatment because of its lower cost.
End Stage Treatment For Neovascular Galucoma:
Total angle closure by the peripheral anterial synechiae is found in this end stage of NVG. The patient with this phase of NVG has no remaining useful vision. The prime aim in the treatment of end stage of neovascular glaucoma is to control the pain.
- Topical Atropine- Treatment begins with medications which include the use of topical atropine 1% and the use of steroids.
- Contact lenses- Using a bandage contact lens is advised in case there is an occurrence of corneal decompensation.
- Cyclodestructive Procedure- If medical treatments do not work, employing cyclodestructive procedures are recommended in this stage of NVG.5 The prime goal here is to lower the IOP by destroying secretory ciliary epithelium or reducing the flow of blood to the ciliary body.
- Nd Yag Laser Treatment- Two approaches of Nd: YAG laser transscleral cyclophotocoagulation is noted in treating end stage NVG. One is the contact approach and other is the non contact approach.6
- Cyclocoagulopathy- Direct laser cyclophotocoagulation is also performed in some cases of end stage NVG treatment. However its role is secondary and controlling or lowering of IOP with this is pretty limited in its success rate.
- Retrobulbar Alcohol Injections- Retrobulbar alcohol injections are used after all medical and surgical treatments are performed. This is done to control pain. However it must also be noted that there are complications like Opthalmoplegia, blepharoptosis etc involved with this type of treatment method.7
- Anti-Vascular Endothelial Growth Factor- The recent research suggests anti-vascular endothelial growth factor (VEGF) agents are effective in treating neovascular glaucoma.8
- Glaucoma: Causes, Types, Signs, Treatment- Surgery, Laser, Filtering, Drainage Implants
- What is Narrow Angle Glaucoma: Causes, Symptoms, Treatment
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