In neovascular glaucoma (NVG), blood flow is impaired to tissue in the eye, causing emergency blood vessel formation that leads to inflammation and blocks the eye’s fluid drainage system. The condition happens as a result of other diseases, most commonly proliferative diabetic retinopathy (PDR) and retinal vein occlusion (RVO). NVG is a very serious kind of glaucoma that can arise suddenly and cause blindness if not treated right away to control the rapid increase in internal eye (intraocular) pressure from fluid build-up. Researchers have discovered that vision in certain patients may improve after the use of glaucoma drainage devices to treat these conditions. 

What They Did

In a study published in BMC Ophthalmology, researchers at the University of Miami’s Bascom Palmer Eye Institute examined treatment outcomes one year after surgical implantation of glaucoma drainage devices (GDD) in people with different causes of NVG. To their knowledge, no other studies had compared surgical treatment results for NVG in people with different causes of the disease.

Concerning their objective:

• The study examined changes in visual acuity (VA) one year after NVG surgery in people with PDR, RVO, and other NVG causes.
• It also looked at how well the devices lowered intraocular pressure (IOP) after one year.

Concerning their methods:

• 20/400 was used as the lower threshold for meaningful vision.
• Successful surgery was defined as IOP of 5-21 mmHg, with or without medication, no follow-up surgery for IOP, and no loss of light perception.
• The researchers looked at medical records of people with NVG who underwent GDD surgery at University of Miami facilities over a nearly eight-year period.
• Patients had documented NVG with intraocular pressure over 21 mmHg prior to surgery.
• Patients were older than 18, had no history of glaucoma procedures, and were followed up after three months.
• One hundred twenty (120) eyes met the inclusion criteria, with data obtained at three and 12 months post-surgery.
• Of the 120 eyes, 61.7% had NVG because of PDR, 23.3% from RVO, and 15% from other causes.
• Patients were implanted with either an Ahmed or Baerveldt drainage device, or both.

What They Found

Results were mixed after one year, but certain patient groups with NVG had better vision with their new GDD.

Concerning the two devices:

• No significant difference in IOP was found.
• On average, people receiving the Baerveldt device were able to take less medication than those with Ahmed.

Concerning NVG causes:

• Around 51% of people with PDR experienced meaningful vision versus 29% of people with RVO.
• Around 75% of all people saw lower IOP, though it was lower in the 15% with other NVG causes (11.9 mmHg) than PDR (17.1 mmHg) and RVO (15.6 mmHg).

Overall, both devices were effective, but people with NVG caused by PDR had better vision results than NVG caused by RVO.

What It Means

The authors note their study was limited by its retrospective nature. They recommend that prospective (forward-looking) studies comparing Baerveldt, Ahmed, and a type of laser surgery called cyclophotocoagulation be “the next phase of discovery.”

*McNulty, R. (2022, January 7). Retrospective Study Finds Neovascular Glaucoma Etiology May Affect Surgical Outcomes. American Journal of Managed Care. https://www.ajmc.com/view/retrospective-study-finds-neovascular-glaucoma-etiology-may-affect-surgical-outcomes