Victoria L. Tseng, MD, PhD: Racial, Ethnic Disparities in Neovascular Glaucoma

Victoria L. Tseng, MD, PhD

Credit: UCLA Stein Eye Institute

Individuals belonging to racial and ethnic minority groups may have a higher likelihood of neovascular glaucoma and need for surgery to lower intraocular pressure, compared to non-Hispanic White individuals, according to new research.

The investigation, presented at the 127th Annual American Academy of Ophthalmology (AAO) Meeting in San Francisco, California, examined racial and ethnic differences in the incidence, treatment patterns, and visual outcomes of neovascular glaucoma among eyes in the Iris Registry.

Among more than 300,000 eyes with proliferative diabetic retinopathy, retinal vein occlusion, or ocular ischemic syndrome, the incidence of neovascular glaucoma was reported as nearly 2% from 2014 to 2019.

In an interview with HCPLive at AAO 2023, presenting investigator Victoria L. Tseng, MD, PhD, a glaucoma and cataract specialist and epidemiologist researcher at Doheny Eye Institute and an assistant professor in residence in the department of ophthalmology at UCLA Stein Eye Institute, described the key takeaways from the analysis on the rates of neovascular glaucoma by race and ethnicity, as well as the factors related to the incidence and screening for the disease.

This transcript has been edited for clarity.

Can you describe the importance of identifying racial and ethnic disparities across medicine and, within ophthalmology?

I think since the onset of the COVID-19 pandemic, racial and ethnic disparities in healthcare have really come to light in our medical community. We’ve always known that these disparities existed. But, with everything that happened in the pandemic, these disparities just really became extremely apparent in so many more ways than we could ever imagine.

Because the social determinants of health and all these aspects of medical care that do not occur directly in the hospital became much more obvious. I think this is where these disparities really got magnified, with everything that was happening during the pandemic. It’s really important to examine these factors because we want to take the best care that we can of our patients. But that involves so much more than just what happens in the 5-minute encounter between a doctor and a patient.

You really need to think about all the aspects of that patient’s experience – how they are getting to their medical appointments, and what are their transportation needs. What is their social support at home? What are their cultural beliefs about medicine, treatments, and surgeries? And what is their ability to follow up if you perform an intervention on them? Really, how all these factors are going to impact their care and their final outcome? Those are kind of the things that we really want to pay attention to when we’re thinking about these disparities.

What is neovascular glaucoma? Can you describe the presentation and detection of the disease?

Neovascular glaucoma is what we call secondary glaucoma, meaning that it’s a cause of blindness, due to degeneration of the optic nerve, with a cause that can be identified. With the bread-and-butter, primary open-angle glaucoma that we think about, a lot of people have this disease, but we don’t know why it happens. Whereas, with neovascular glaucoma, there is an identifiable cause, and the cause is low oxygen supply to the eye, which happens when the retina, the back of the eye, gets a condition cutting off the oxygen supply. This is what we call retinal ischemia.

There are several different conditions that can cause retinal ischemia, but the most common ones that we think about are proliferative diabetic retinopathy, central or branch retinal vein occlusions, and ocular ischemic syndrome. When we have these retinal conditions, it’s important to treat the underlying cause here, which is the decreased oxygen supply. That can be done by applying laser treatment to the eye or injecting anti-VEGF medications. Both help control a process we call angiogenesis, or neovascularization, which is where the eye will start to sprout abnormal blood vessels as a means of trying to increase the decreased oxygen supply.

If these abnormal vessels grow around the front of the eye, they can clog up the drainage system, prevent fluid from draining from the eye, lead to high pressure, and damage the optic nerve. When we’re thinking about neovascular glaucoma, it’s a very end-stage condition of these ischemic conditions, because the retinal ischemia must have gone uncontrolled for a period before this abnormal blood vessel growth can spread to the front of the eye.

What were the key takeaways from your analysis of the racial and ethnic disparities related to neovascular glaucoma?

We looked at several factors related to neovascular glaucoma. First, we wanted to see people who are at risk for this condition, meaning people who already have a retinal ischemic disease – what is the incidence or risk of getting neovascular glaucoma, and does this differ by race and ethnicity?

Then, in those diagnosed with neovascular glaucoma, the differences and how we treat these people by race and ethnicity are twofold. One part of the treatment is treating the ischemia with retinal laser or anti-VEGF injection, and then the other part of it is treating the glaucoma, by lowering the intraocular pressure with surgery. In the first part, what we found was that racially and ethnically minoritized individuals, those who identified as Black, Hispanic, or Latino, who had retinal ischemic disease, had a higher risk of getting neovascular glaucoma, compared to those who identified as White.

Basically, of the people who are at risk for getting this end-stage complication, if you’re from a racial or ethnic minority background, you have a higher risk of getting the bad complication of retinal ischemic disease. Then, in the second part, in people who were already diagnosed with neovascular glaucoma, we found that there were no racial and ethnic differences in the rate of getting treatment for retinal ischemia, meaning retinal laser or anti-VEGF injection.

But, in patients who identified as Black, there was a higher risk of needing surgery to lower the intraocular pressure, compared to patients who identified as non-Hispanic White. We tend to reserve glaucoma surgery for severe cases that cannot be controlled by medication. It may be that these people who are Black who have neovascular glaucoma have to a worse degree, a disease that can’t be controlled medically.

What factors are related to these higher incidences among these racial and ethnic groups?

I think there are a lot of factors. I work at one of the UCLA safety net hospitals supervising our residents and it’s not uncommon for us to see a brand-new patient who’s never been to the hospital coming in with neovascular glaucoma, and that’s the time that they can find out they have diabetes.

Obviously, that’s not ideal, but that’s one thing that can happen. Patients may not be aware of the need to see an eye doctor if they’re diabetic or the need to even get screened for their diabetes. There may be a delay to the diagnosis of the retinal ischemia condition after they are diagnosed, then there is a need to treat this condition.

Oftentimes, they don’t really feel any issues when they first get diagnosed with diabetes in their eye. And we’re telling them they need laser. People may not understand why they need this, or they may understand it, but they may be unable to present to the hospital for these repeated laser sessions, or repeated injections, monthly. If there’s any delay or undertreatment of these individuals, then their risk of getting neovascular glaucoma can certainly go up after they’re diagnosed.

There’s the need to treat glaucoma aggressively with medication and with continued treatment of ischemia. If there’s a gap in the understanding of these factors, at that point, or the ability to follow up, that can further worsen the condition.

Would improvements to screening and detection help reduce these rates?

I think we can use diabetes, as an example, because that is certainly one of the most common causes of neovascular glaucoma. In a perfect world, everybody who was diagnosed with diabetes would get a dilated eye exam to screen for diabetic retinopathy immediately and on a regular basis, at least once a year, forever. Then, they’d be able to be counseled on the need for controlling their blood sugar and blood pressure.

If they could really keep their diabetes under control, that should ideally prevent them from ever getting diabetic retinopathy in their eye. Even if they get mild forms of diabetic retinopathy, those are not visually threatening, like the proliferative form. If we were able to have rigorous and improved screening, with good follow-up, that theoretically could prevent complications like these from happening.

References

_{Tseng VL. Neovascular Glaucoma: Racial/Ethnic Disparities in Incidence, Treatment Patterns and Visual Outcomes. Presented at the 2023 American Academy of Ophthalmology Annual Meeting, November 3 – 6, 2023.}