When my husband, Eric Haseltine, PhD, and I interviewed Mark Lenzi, who reported experiencing anomalous health incidents (AHI), commonly known as Havana syndrome, Mark told us that abnormal eye movements were among the reasons he was medically evacuated from Guangzhou, China, in 2018.
Those abnormal eye movements were discovered when Mark took the U.S. State Department Havana Acquired Brain Injury Tool (HABIT) test.
The HABIT test evaluated eye convergence, eye tracking, vestibular, auditory, and neurocognitive abilities, and was administered to officers and family members in the field to ”evaluate medical findings associated with directed energy exposure in certain foreign environments" (per the United States government). See photos below.
Given Mark's abnormal eye movements, the question is: Could abnormal eye movements in other victims provide clues that help doctors better understand and diagnose AHI cases?
Several studies suggest that they could.
But first, what is Havana Syndrome?
Havana Syndrome
Havana syndrome refers to a collection of symptoms reported by U.S. government personnel and others, often beginning suddenly with intense headaches, dizziness, and unusual auditory or sensory experiences, as described in detail by investigative reporters Michael Ray and Oriana Zill de Granados in their 2026 book “The Havana Syndrome”. [1]
Some affected individuals report persistent headaches, tinnitus, balance problems, insomnia, visual difficulties, and cognitive complaints lasting months to years. Although some symptoms resemble those associated with concussion or mild traumatic brain injury, the underlying causes of AHIs remain uncertain. [2–4].
Brain scans and other objective tests of AHI patients have yielded conflicting results, prompting a number of prominent experts to assert that AHI symptoms are purely due to a mass psychogenic illness. [7].
To answer those skeptics, objective measures of injury are needed.
Eye movement abnormalities offer exactly that type of objective evidence.
Three Eye-Movement Abnormalities Worth Knowing About
A 2018 University of Pennsylvania study of 21 U.S. government personnel reporting AHIs found ocular motor abnormalities in 71 percent of victims during neurological evaluations. [3]
Below are the details of what they found.
1. Convergence insufficiency
When we read a book or look at a phone, both eyes must turn inward to focus on a nearby object. If they cannot coordinate this movement adequately, the problem is called convergence insufficiency, which may cause blurred or double vision, eye strain, and headaches. Convergence insufficiency was reported in 52 percent of AHI patients in the 2018 JAMA study.
2. Abnormal smooth pursuit
Smooth pursuit allows the eyes to follow a slowly moving object without moving the head. For example, a clinician may ask a patient to follow a target moving horizontally and vertically.
When smooth pursuit is impaired, the eyes may fail to track the target continuously. Instead, they make a series of small corrective movements, sometimes described as catch-up saccades.
Abnormal smooth pursuit was reported in 52 percent of AHI patients.
3. Saccadic dysfunction
Saccades are the rapid movements we make when shifting our gaze between objects or lines of text. Clinicians can assess whether these movements are accurate, appropriately timed, and sufficiently fast. If they are abnormal, the phenomenon is called saccadic dysfunction, which was reported in 47 percent of AHI patients.
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The Eyes and Inner Ear Work Together
Eye movements are closely connected to the vestibular system, which helps us maintain balance and orientation.
The 2018 University of Pennsylvania study also reported abnormalities in balance and vestibular assessments in 81 percent of patients, including the vestibulo-ocular reflex, which stabilizes vision when we move our heads. [3]
A subsequent 2020 study published in Frontiers in Neurology examined eye coordination and pupil responses in people reporting AHIs. [5]
The researchers analyzed data from 19 affected individuals and compared their responses with those of 17 individuals with acute mild traumatic brain injury and 62 control participants without injury.
The tests included the pupillary light reflex, which measures how the pupils respond to light, and vergence responses, which involve coordinated eye movements when viewing targets at different distances.
The investigators reported patterns of eye movement and pupil responses that consistently differed among the three groups.
Their analysis suggested that these measurements might help researchers distinguish between AHI victims, mild traumatic brain injury patients, and unaffected individuals.
Results of a Larger Study
In 2024, a larger study published in JAMA compared 86 individuals reporting AHIs with 30 government control participants. [6]
Its overall findings did not demonstrate significant differences across most of the clinical and research assessments.
However, four specific ocular-motor measurements showed statistically significant differences between the groups after adjustment for multiple comparisons. These involved smooth-pursuit latency, saccadic pursuit, response latency to leftward target movement, and peak vertical saccadic velocity.
Those details deserve attention. Although the overall findings were largely negative, the specific eye-movement results suggest that the question is not settled.
The timing of testing may also matter. Participants were assessed at varying intervals after their reported incidents, and some had received several months/years of treatment and rehabilitation before testing. These factors complicate result interpretations.
Summary
The United States government tested eye movements of AHI victims in the field and, according to Mark Lenzi, based medical evacuations on -among vestibular studies and other tests- abnormal eye movements..
The 2018 University of Pennsylvania study documented frequent abnormalities in convergence, smooth pursuit, and saccadic function of AHI victims' eyes.
A 2020 study identified distinctive patterns in eye and pupil responses in AHI victims, while a larger 2024 study found statistically significant differences in four specific ocular-motor measurements despite largely negative comparisons across the broader testing battery.
Taken together, these elements provide reasons to investigate ocular-motor function further in AHI victims.
More importantly, the objective eye movement findings offer vindication for AHI victims who have had to endure accusations of mass psychogenic illness and fakery on top of debilitating symptoms and lasting damage to their careers and reputations.
Copyright 2026 @Chris Gilbert, MD, PhD