Department of Research & Evaluation News

Eye specialists at Kaiser Permanente Southern California studied whether using a standardized testing criteria among younger adults could improve care, reduce unnecessary testing, and potentially reduce blindness from glaucoma.

The eye specialists, working with researchers at University of Southern California,  published Outcomes of Glaucoma Referrals in Adults Aged 18 to 40 years in JAMA Network Open in February 2025.

“Glaucoma is a leading cause of blindness,” said research co-author Grace Richter, MD, a glaucoma specialist at the Kaiser Permanente Los Angeles Medical Center. “Early detection and treatment, before patients are symptomatic, is critical to prevent unneeded blindness. Optimizing our glaucoma monitoring strategies is key.”

Few glaucoma studies looked at younger patients

However, few studies have researched glaucoma and younger adults, since typically the disease affects older people.

This study showed that:

• Of 6,827 adults ages 18 to 40 years referred for glaucoma evaluation, only 8.2% were diagnosed within 2 years.
• A risk threshold based on 3 variables could potentially reduce unnecessary referrals and testing by 28%.
  • The risk threshold model effectively stratified patients as high or low risk.
  • The 3 variables were age, intraocular pressure (the pressure within the eye) and the cup-to-disc ratio (a comparison measurement within the optic disc).
• The overall prevalence of glaucoma among patients ages 18 to 40 is low at 0.19%.

• Black and Hispanic patients were at higher risk for not receiving a glaucoma evaluation after referral.

Many studies look at higher-risk patients in the older adult populations but there are few studies in the younger age cohort with fewer conditions that put them at risk, noted John Shan, MD, chief of Optometry at Kaiser Permanente Panorama City Medical Center and adjunct clinical assistant professor of Ophthalmology at the USC Keck School of Medicine.

Robust health records key to answering question

“I had always suspected that the answers to many mundane and common clinical questions were right under our noses within the treasure trove of data Kaiser Permanente has been housing since the introduction of our electronic health record system in 2004,” Dr. Shan said. “What started as an impromptu discussion with a colleague at Keck, became a research study that came to fruition.”

Dr. Shan said the study findings should give clinicians “more peace of mind knowing younger patients have a relatively low risk for glaucoma and provide a clearer guideline and breakdown of risk attributes to help better stratify a patient’s risk.”

Follow-up among glaucoma patients can be poor

The low number of patients who followed up on their referrals was disappointing but not surprising to the authors.

“Unfortunately, compliance and adherence among glaucoma patients are notoriously poor,” Dr. Shan said. “It is an insidious condition that usually occurs with little to no symptoms until late in the disease process. Thus, patients may not feel the need or urgency to follow up for testing or treatment.”

This was especially true for patients who were Black or Hispanic. That finding highlights that health insurance coverage is only one of many social determinants of health, including health literacy and cultural beliefs, that may contribute to disparities in following up on eye care referrals and potentially, glaucoma outcomes.

“Despite having health insurance coverage, there are many reasons why patients of different ethnic groups may not receive the care they need,” Dr. Shan said. “Generally speaking, the largest barrier to care is not having coverage. Yet, among insured Black and Hispanic patients at Kaiser Permanente Southern California, the follow-up compliance was still poor. Therefore, there must be other causes for why these groups are not seeking  proper care. That is yet one more issue that needs more research.”

Findings should encourage others

The doctors said that their intent was to use an evidence-based approach to optimize the screening program of glaucoma and allow clinicians to target specific clinical features that will reduce unnecessary referrals and costly tests for low-risk patients. And they were pleased to be able to do research with both the potential to save money and save peoples’ sight.

“We hope this encourages other clinicians to consider doing research and helping the medical field progress,” Dr. Richter said. “Coming back full circle, there are so many answers to questions that I’m sure many clinicians have always wondered about.”

The findings, though, also left the doctors with more questions they hope to answer with future research. They include analyzing the effectiveness of the current program at Kaiser Permanente Southern California, determining the implications for older patients and how their risk factors differ from this younger cohort, and following this initial group of young patients over the years to determine how many get assessed after a second referral, how many begin treatment, and how many develop glaucoma.

In addition to Dr. Richter and Dr. Shan, other authors on the paper include first author Tanner Frediani, BS; senior author Benjamin Y. Xu, MD, PhD; Kristy Yoo, BA; Austin Cho, BA; and Kent Nguyen, OD, of the Keck School of Medicine, University of Southern California; and Jennifer Louie, BS, of the Vision Essentials Regional Office, Southern California Permanente Medical Group.