乌鸦传媒

Attention deficit-hyperactivity disorder (ADHD) was associated with a diagnosis of keratoconus in males, according to an Israeli population-based cross-sectional study.

Looking at the medical records of over 900,000 military members, those with keratoconus were more likely to be diagnosed with ADHD compared with the general population (OR 1.58, 95% CI 1.38-1.81, P<0.001), and results remained significant after adjustments for age, sex, and intellectual status, reported Margarita Safir, MD, of Shamir Medical Center in Zerifin, and colleagues.

When stratifying by age, keratoconus was associated with ADHD in males (OR 1.62, 95% CI 1.39-1.90, P<0.001), but not in females (OR 1.29, 95% CI 0.96-1.74, P=0.09), they noted in.

However, "despite the previous small reports connecting anxiety, obsessive-compulsive disorder [OCD], and autism to repetitive eye rubbing, these disorders were not associated with keratoconus in our study," Safir told 乌鸦传媒.

The most important risk factor for keratoconus is repetitive eye rubbing, which irritates the corneal surface.

"Keratoconus is the most common type of corneal ectasia, where progressive thinning and conical protrusion of the cornea occur," Safir explained. "This structural alteration induces irregular astigmatism, myopia, and visual distortion, which may ultimately result in blindness. Its prevalence is estimated to be 50-230 cases per 100,000, and onset usually occurs during adolescence or early adulthood."

Treatment includes corrective lenses such as eyeglasses or specialized contact lenses. "Corneal cross-linking, an intervention fortifying corneal collagen, is indicated when disease progression needs to be halted," she added. "In refractory instances, surgical interventions such as corneal transplantation may be necessary."

While the study did not address whether eye rubbing in ADHD caused the higher rates of corneal damage, Safir noted that "repetitive body movements as a group are known to be associated with ADHD. Repetitive eye rubbing has been hypothesized to serve as a method for stress relief via induction of the oculocardiac reflex with resultant vagal stimulation."

In an , Maria A. Woodward, MD, MSc, and Emily L. Vogt, BA, of the University of Michigan in Ann Arbor, highlighted the power of the human desire to scratch itches. "While an itch may initially be chemically triggered sensation in response to our environments, it can quickly progress to a learned behavior that we repeat even in the absence of environmental stimulation."

"Eye rubbing can alter the delicate environment housing corneal nerves, causing nerve degeneration over time and resulting in keratoconus," they wrote. "Subsequently, the visual disturbances, pain, and irritation resulting from keratoconus may stimulate further eye rubbing and itching, worsening the disease progression and prognosis."

While it's unclear why mental disorders other than ADHD were not linked to keratoconus in the study, smaller sample sizes could be the explanation, they noted.

What can clinicians do with the information from the study?

Safir suggested that they proactively ask patients about eye habits, especially eye rubbing, and provide "targeted guidance" against it.

Woodward and Vogt recommended against nagging patients to stop rubbing their eyes. Instead, "for example, we can recommend cooled, preservative-free artificial tears. If the patient still struggles, we can consider prescription medications or surgical treatment to reshape the cone via cross-linking or keratoplasty. Many of our patients with keratoconus are young, and badgering them or their parents to change their intrinsic response to itching is less appropriate than providing care for itching and accommodations for their intrinsic response to the itch."

The study included the medical records of 940,763 military members in Israel who underwent physical and mental evaluations from January 2011 through December 2021. Mean age was 17.6, and 59.3% were male.

A total of 1,533 (0.16%) were diagnosed with keratoconus (72.8% male). Of this group, 15.9% had ADHD.

Looking at other psychiatric disorders, the prevalence for anxiety disorders was 0.5%, 0.1% for OCD, and 0.1% for autism.

乌鸦传媒 asked Safir if the numbers of patients with anxiety disorders, OCD, and autism were unusually low, as the NIH that 19.1% of U.S. adults had an anxiety disorder within the past year. She noted that the numbers don't include mild cases that didn't significantly impair everyday function or lead to psychiatric evaluation.

"We believe this fact does not affect the reliability of our results, since the more clinically significant cases -- where psychiatric aid would naturally be sought -- are the ones where more psychogenic eye rubbing would be expected," she explained.

Study limitations included the lack of information about severity of disease and the timing of whether ADHD or keratoconus was diagnosed first in individual cases. There was also no information about whether the patients actually rubbed their eyes.

Comment