Lee Dong-gun Lee Dong-gun
Actor Lee Dong-gun learned he has ankylosing spondylitis, a chronic spine disease, while filming My Little Old Boy. Wikimedia Commons

South Korean actor Lee Dong-gun received a life-altering diagnosis of ankylosing spondylitis while filming an episode of My Little Old Boy, a popular SBS television show. The 45-year-old star had been experiencing severe and ongoing inflammation in his right eye, prompting a hospital visit that revealed the underlying condition.

Doctors linked his symptoms to a form of arthritis that causes inflammation in the spine and pelvis, potentially leading to reduced flexibility and possible fusion of bones over time.

Eye Pain Leads to Unexpected Diagnosis

During the episode aired on 28 September 2025, Lee visited a hospital for recurring pain and light sensitivity in one eye. He told the doctor that his right eye had been bloodshot and painful for over a year, with his vision also significantly affected.

The doctor identified the issue as uveitis, an inflammation affecting the middle layer of the eye. Due to the prolonged nature of the symptoms, further investigation was done. Imaging revealed inflammation in the sacroiliac joint — the connection between the spine and pelvis.

What Is Ankylosing Spondylitis?

Based on the X-ray results and Lee's medical history, the physician diagnosed ankylosing spondylitis, also known as axial spondyloarthritis. This chronic inflammatory arthritis can cause the vertebrae in the spine to gradually fuse over time.

Fused vertebrae lead to reduced flexibility, pain, and a hunched posture. In some cases, when ribs are affected, breathing deeply becomes difficult. Ankylosing spondylitis has no known cure but can be managed through long-term treatment.

Initial signs of the disease typically include persistent lower back pain and stiffness, especially during the morning or after inactivity. In some cases, the neck and hips may also be affected. Inflammation is not limited to the spine and can also present in the eyes and major joints.

Lee recalled waking up ten years ago with severe, stabbing pain in his back, so intense that even breathing was difficult. Although the pain passed at the time, it aligned with symptoms of early-stage ankylosing spondylitis.

Doctors later confirmed the disease was at stage 2 or 3 out of 4. He also tested positive for a genetic marker associated with the condition, though he reported no known family history.

Prevalence and Demographics

Ankylosing spondylitis is relatively rare, with global estimates ranging from 0.1% to 1.4% of the population. In South Korea, as of 2023, approximately 55,375 people — just over 0.1% of the total population of 51.7 million — had been diagnosed.

The condition is more common among men, with 40,208 male patients reported compared to 15,167 women. Those in their 40s made up the largest group (28.2%), followed by people in their 30s (22%) and 20s (12.9%).

Treatment and Lifestyle Adjustments

Though the disease cannot be cured, treatment can slow its progress and relieve symptoms. Doctors advised Lee to make dietary changes, avoid alcohol, cigarettes, sugar and refined flour, and take vitamin C to help reduce inflammation.

One case was cited where inflammation markers improved significantly after switching to a diet including perilla oil. Physical therapy and regular exercise also play a central role in ongoing care.

What Happens Next for Lee Dong-gun?

Lee Dong-gun rose to fame after his breakout role in the 2004 drama Lovers in Paris. He began his career as a singer before transitioning into film, television, and musicals.

Experts say this diagnosis shines a light on the importance of early medical evaluation for unexplained symptoms. Although his condition requires lifelong management, treatment can help maintain mobility and slow the disease's progression.

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