Research has demonstrated that obesity and overweight are significant risk factors for several ocular diseases, but can weight loss improve ocular health? With up to 51% of the US population projected to experience obesity by 2030, clinicians and patients can benefit from understanding the potential value weight loss has for improving glaucoma, diabetic retinopathy (DR), dry eye disease (DED), and other other ocular pathologies.¹

Established Links Between Obesity and Ocular Disorders

Obesity is associated with a variety of ocular pathologies, which include glaucoma, floppy eyelid syndrome, and DED. 

One investigation found that obesity indicators like body mass index (BMI), waist-hip ratio, and abdominal fat were independent risk factors associated with cataracts.² Another study showed that for each unit increase in BMI, a patient is 6% more likely to have higher intraocular pressure (IOP). Yet another investigation shows that individuals with obesity have a significantly higher risk of primary open-angle glaucoma (POAG).¹

Patients with obesity also have a higher risk of developing DR, and those with a higher BMI develop it earlier.² Overweight and obesity, however, are not the only weight-related risk factors for DR, as individuals with underweight (BMI<20 Kg/m²) also demonstrated an increased risk of DR.²

“Obesity, particularly abdominal obesity, is associated with multiple eye diseases, including glaucoma, ischemic optic neuropathy, DR — specifically in Western populations, retinal vascular occlusions, and hypertensive retinopathy,” A. Paul Chous, OD, MA, FAAO, explained. “These relationships are likely multifactorial and include pathological processes associated with obesity like vascular inflammation, alterations in gut hormones modulated by the microbiome, and sleep disorders such as apnea and insomnia.”

“One significant concern is the association between obesity and type 2 diabetes, which can lead to DR and increased risk for vision loss,” according to Breanne B. McGhee, OD, MEd, FAAO, an assistant professor at Pacific University College of Optometry. “Additionally, obesity has been correlated with an increased risk of glaucoma, AMD [age-related macular degeneration], dry eye syndrome, cataracts, and vascular occlusions.”

Research Has Yet to Substantiate a Preventative Effect of Weight Loss on Ocular Disease

While several studies have determined that excess weight negatively affects eye health, a correlation between weight loss and improved eye health has not yet been established. 

“The evidence supporting a direct link between weight loss and improvements in eye health is not as robust as the research connecting excess weight to eye health problems. Nonetheless, there are reasons to believe that weight loss can positively affect eye health,” Dr McGhee said. “For example, in individuals with type 2 diabetes, weight loss can lead to better blood sugar control, potentially reducing the risk of DR and other diabetes-related eye complications. Additionally, weight loss can reduce chronic inflammation, which may have a favorable impact on different eye conditions.”

Dr Chous acknowledges the dearth of research on associations between weight loss and improved ocular health. “One study showed that obesity was related to increased risk of POAG, but that weight loss did not particularly attenuate that risk,” he said. “We definitely need more long-term studies evaluating improvements in eye health with weight loss. The strongest case can probably be made for the prevention of DR, although studies again indicate that weight loss does not consistently result in less progression of pre-existing DR. To the extent that reduced weight lowers blood pressure, it is highly probable that it also mitigates hypertensive retinopathy, anterior ischemic optic neuropathy and retinal vein occlusion-disorders strongly linked to hypertension. But again, we really need long-term follow up of these patients.” 

Obesity is associated with systemic metabolic changes that can influence eye health, and it is believed that adipose tissue produces inflammatory cytokines that can cause the disease to progress.¹

“The biological model for reduced risk stems from reduction of specific adipokines —inflammatory proteins released by visceral adipose cells, reduced ‘leaky gut’ from microbiome endotoxins that drive inflammation, and reduced blood pressure,” Dr Chous explained. “Lutein and zeaxanthin, protective macular pigments against oxidative damage to the macula, are also stored in fat so, theoretically, weight loss (reduced fat mass) should result in greater serum bioavailability of these critical carotenoids for active transport into the macula and brain, resulting in greater protection against vision loss from common macular diseases like AMD and DR/diabetic macular edema as well as cognitive dysfunction.”

Methods of Weight Loss and Their Effect on Ocular Health

“Adopting a healthier lifestyle often involves changes like a better diet, regular exercise, and avoiding smoking, all of which collectively support overall eye health,” Dr McGhee said. “While specific research on the effects of weight loss on eye health may be limited, the broader benefits of weight loss for overall health are well-documented, and by addressing obesity and its associated health risks, individuals are likely to experience positive effects on their eye health indirectly.”

Traditional diet and exercise, intermittent fasting, weight-loss surgery, and weight-loss drugs can all help patients lose weight, but none of these specific approaches can be linked with improved outcomes in ocular disease. Patients must choose a method that factors in their individual health concerns and preferences, according to Dr McGhee, who cautions that  “the impact of these methods on eye health may also depend on the presence and severity of eye conditions.” 

Weight-Loss Medications

Semaglutide (Novo Nordisk) has been approved by the US Food and Drug Administration (FDA) for chronic weight management in adults with a BMI of 27 kg/m² or greater who have at least 1 weight-related comorbidity, such as type 2 diabetes or hypertension, or in adults with a BMI of at least 30 kg/m².³ There are 3 labeled approvals for semaglutide: once-weekly subcutaneous injections Ozempic® and Wegovy®, and Rybelsus®, a once-daily pill.

“Prescription weight-loss drugs like Ozempic can be beneficial for individuals who struggle to lose weight through diet and exercise alone, potentially reducing the risk of obesity-related eye issues,” said Dr. McGhee.

While studies show that Ozempic can significantly help people control blood sugar, the medication can cause vision changes, including blurred vision and worsening DR. These short-term side effects are more prevalent in older adults.⁴

“The effects of drug-induced weight loss likely depend on the specific agent,” Dr Chous explained. “For example, semaglutide is known to reduce cardiovascular risk but may be associated with worsening DR in patients who already have DR. We think this is a result of the rapid, significant reduction in blood glucose that upregulates mitochondrial reactive oxygen species — so-called glycemic re-entry retinopathy — and increased hypoglycemia that recently has been shown to massively upregulate HIF-1alpha release by retinal Muller cells, an antecedent to VEGF [vascular endothelial growth factor], particularly when this drug is used in combination with insulin.”

The FOCUS study (ClinicalTrials.gov Identifier: NCT03811561), which is expected to conclude in February 2027, will evaluate the long-term effects of semaglutide on DR in individuals with type 2 diabetes.

Intermittent Fasting

Intermittent fasting is increasingly becoming a popular weight-loss method. During intermittent fasting, most daily calories are consumed within a specific period, and there are no caloric or dietary restrictions, making it appealing to those who do not want to adhere to a strict diet.⁵

“I have had some success discussing and recommending alternate daily fasting with patients who are at least 40 pounds above their target weight,” Dr Chous said. “Several of these patients who were on insulin for poorly controlled type 2 diabetes were able to discontinue insulin therapy altogether and achieved HbA1c under 6.5% on metformin alone once the weight came down. It’s totally safe from an ocular standpoint provided the patient has mild or no DR, but I always have the patient talk with their PCP or cardiologist just to get clearance.”

While this approach has provided cardiometabolic benefits in clinical settings and improved longevity in animal studies, there is limited evidence that this weight loss method improves ocular disorders.⁵

Weight-Loss Surgery

Weight-loss surgery, which includes Roux-en-Y gastric bypass and gastric band procedures, has positive benefits for glycemic control in patients with type 2 diabetes. However, like other methods of weight loss, the procedure’s ability to improve ocular disease is unsubstantiated, with some studies finding that DR worsens after surgery.

In studies with 1 year of follow up or less, patients demonstrated worsening DR severity, yet in studies with more than 5 years of follow up, DR worsening is less prevalent.⁵ A 2023 investigation revealed that patients with type 2 diabetes who underwent bariatric surgery did not have an increased risk of short- or long-term DR worsening.⁶ In another study that included patients who underwent Roux-en-Y gastric bypass, researchers noted a significant drop in BMI and an improvement in blood lipids, but no statistically significant change in ocular surface or tear film.⁷ 

In a 2023 literature review, investigators found that bariatric surgery positively affected retinochoroidal microcirculation and decreased IOP. However, the effect of postoperative weight loss on choroidal thickness and retinal nerve fiber layer was unclear.⁸ In a separate review, researchers at Vanderbilt University found that mean IOP decreased by 21% 1 year after bariatric surgery and determined that certain weight loss surgeries may protect against POAG, AMD, and cataract development.¹

“Bariatric surgery, a more invasive option, often results in rapid and substantial weight loss, making it effective for reducing the risk factors associated with eye conditions like diabetes and hypertension,” Dr. McGhee explained. “However, it carries risks and variable long-term outcomes like nutritional deficiencies, dumping, infection risk, and surgical complications.”

Bariatric surgery can lead to malabsorption of nutrients, including vitamin D and vitamin A — both of which are critical for maintaining healthy eyes. Vitamin D deficiency has been associated with an increased risk of AMD, and vitamin A is crucial for normal vision, according to Dr McGhee. 

Traditional Diet and Exercise

Traditional diet and exercise are tried and true methods of improving overall health, and increasing vigorous physical activity to at least 3 times a week is associated with a 25% reduction in the rate of AMD progression.¹ 

“Old-fashioned diet and exercise offer a safer and sustainable approach to weight loss, gradually stabilizing blood sugar levels, reducing inflammation, and lowering blood pressure, all of which contribute to better eye health,” said Dr McGhee.

“Old-fashioned weight loss via diet and exercise is probably most beneficial because it positively impacts inflammatory pathways and overall vascular health,” Dr Chous agreed. “Lowering intake of refined carbohydrates — particularly high-fructose corn syrup, but also high glycemic index foods — definitely reduces the risk of sugar toxicity via multiple pathways, including the reduced formation of advanced glycation end products that are known to contribute to AMD, DR, cataract, ocular surface disease and glaucoma.”

Supporting Patients’ Weight-Loss Goals

Despite the benefits of maintaining a healthy weight, discussing the topic with patients can be challenging. However, Dr McGhee and Dr Chous agree that it is important to address obesity and offer support.

“Optometrists are instrumental in the screening and early detection of eye conditions, especially those associated with obesity,” Dr McGhee explained. “They can educate patients on the connection between weight, nutrition, and eye health, empowering them to make informed decisions. Offering basic guidance on nutrition and dietary choices for better eye health and advocating for a healthy lifestyle, including regular physical activity and stress management, are integral aspects of their role.”

Initiating weight-loss conversations may be uncomfortable, but patients who heed this advice and adopt strategies for losing weight will likely experience better disease control, even if it does not translate to improved ocular health. Research shows that individuals who lose at least 10% of baseline body weight have the best chance of diabetes prevention and remission.⁹ 

“I always ask permission to discuss weight with patients by saying, ‘Many eye diseases are linked to excess body weight, and I am all about prevention. Are you comfortable discussing your weight status with me?’ It’s the rare patient who says no,” Dr Chous said.

He recommends all patients follow a low glycemic index, anti-inflammatory Paleolithic-type or Mediterranean diet and provides patients with a handout.

“Collaborating with other healthcare professionals and promoting a multidisciplinary approach to weight management is also beneficial,” Dr. McGhee added. “When weight loss is recommended, optometrists should stress the importance of safe and gradual methods, including balanced nutrition and regular exercise. Weight loss goals should be individualized and reasonable.”

But Dr McGhee also urges patients not to let a healthy lifestyle dissuade them from attending routine eye care visits. “While weight loss can reduce risk factors, it may not necessarily reverse existing eye conditions, emphasizing the importance of regular eye check-ups for monitoring and addressing ongoing concerns,” she said. 

Patients may not step on a scale during routine eye checkups as they do during visits with their primary care provider, but optometrists should be cognizant of their patients’ weight changes and how it may affect their ocular well-being. As uncomfortable as initiating weight loss discussions may be, eye care professionals have a duty to help patients improve their overall health — an obligation that extends beyond simply refracting, writing a prescription, and sending them to the dispensary. While some clinicians may prefer to have a rehearsed script for such patients, Dr Chous offers some simpler advice: “Be kind, empathetic, and treat patients like you would want to be treated.”

This article originally appeared on Optometry Advisor