In doing some spring cleaning I came across this article from Primary Care Optometry News in May 2015: Vertical Misalignment may be Related to Cervical Misalignment. I’ve blogged before about the significance of prescribing for small amounts of uncompensated vertical phoria, and the possible influence of yoga on vertical phoria. Dr. Huff’s article in PCON is more in line with the latter, and dovetails with the idea that proprioceptive feedback may conflict with the vesicular system and influence co-management of the patient accordingly.
Visual misalignment may be related to cervical misalignment
Appropriate assessment and referral can lead to prompt improvement in vision and comfort, build good interprofessional relationships and avoid unnecessary prismatic lens prescriptions and lens remakes.
Recognizing this syndrome in clinical practice has been a learning experience. The first few cases were self-reporting scenarios in which I was an examiner/observer and the patients suspected their visual symptoms were associated with conditions amenable to manipulative therapies. As more of these patients presented, I became increasingly aware of the specific questions to ask and the pertinent tests to perform.
I perform alternate cover testing initially on each patient with his or her habitual refractive correction at 20 feet on the 20/50 line of a projected Snellen chart. To rule out prismatic effects of spectacle lenses, the alternate cover test for subjective vertical phoria is repeated unaided on an isolated 20/80 projected line.
Maddox rod testing is done unaided in free space in primary gaze with a handheld Maddox rod and loose prisms. Either a penlight or a transilluminator is the fixation target, at a test distance of approximately 2 feet.
Associated phoria testing is done at 20 feet with best lens correction through a Green’s refractor using a polarized vectographic chart, taking care to have both the refractor and the patient’s head held level. When possible, the measurement is repeated in free space with the patient wearing either their habitual glasses or contact lenses.
These four cases postulate the anatomical/physiological basis of this phenomenon.
Young female with headaches, neck stiffness
A 20-year-old female complaining of headaches and neck stiffness came in for an exam at the request of her mother, a staff member at the optometric practice. The daughter’s last eye exam was 2 years ago.
Unaided visual acuities were 20/25+ OD and 20/25- OS. Refraction was -0.62 OD sph 20/20+ and -0.75 -0.25 X 075 OS 20/20+. Maddox rod testing indicated 1 prism diopter left hyperphoria, and associated phoria testing measured a 0.50 prism diopter left hyperphoria. The slit lamp and fundus exams were normal in both eyes.
The patient declined new glasses with prism, stating she knew her problem was related to her neck stiffness and would seek chiropractic treatment. She returned 3 weeks later after having had two chiropractic adjustments on her neck. Her headaches had resolved and she had orthophoria vertically as indicated by both Maddox rod and associated phoria testing.
Female with recent headaches at work
A 33-year-old female complained of recent headaches at work. Her last eye exam was 2 years ago, and her vision seems clear.
Her over-refraction in the right eye was plano and +0.50 OS. Maddox rod testing indicated 0.50 prism diopter left hyperphoria, and associated phoria testing measured 1 prism diopter esophoria with vertical orthophoria.
The patient returned after two chiropractic manipulations on her C-1 vertebra. Her vision remained clear, and her headaches resolved. Her over-refraction was plano in both eyes. Her associated phorias indicated both vertical and lateral orthophoria, and Maddox rod indicated ortho vertical phoria.
Elderly female with dizziness
An 88-year-old female complained of dizziness and near-syncope for 3 to 4 days, with vague malaise. She was evaluated at the emergency room and dismissed after a normal CT scan and chest X-ray. She reported falling about 2 weeks ago and catching herself on her left elbow. Her last eye exam was 1 year ago, when testing indicated vertical orthophoria.
At her current exam, her best spectacle-corrected visual acuities were 20/30 OU. Maddox rod testing measured 1 prism diopter left hyperphoria. Alternate cover test showed subjective left hyperphoria. The slit lamp and fundus exams indicated minimal cataracts, consistent with her visual acuities.
The patient was scheduled to see her osteopathic primary care physician that afternoon. I phoned him with my suspicion of cervical misalignment. I saw her on her front porch the next day and she declined an office visit, reporting that her doctor had performed an osteopathic manipulative treatment on her neck, and her symptoms immediately resolved.
Young girl with blurred vision
A 12-year-old girl reported blurred vision with her current contact lenses for approximately 2 weeks. She wore disposable silicone hydrogel lenses and reported no improvement in her vision with lens replacement. Her last eye examination was 7 months ago.
During four previous eye examinations she was found to have vertical orthophoria. She had no headaches or diplopia, but reported mild neck stiffness since sustaining a minor injury to her right cheek during basketball practice about the same time her visual symptoms began.
Her distance visual acuity with her contact lenses was OD 20/25+ and OS 20/20-. Her over-refraction was OD: -0.25 20/25+ and OS: -0.25 20/20. Alternate cover testing indicated subjective left hyperphoria that was repeatable. Maddox rod testing measured 0.50 prism diopter left hyper. A left hyperphoria in primary gaze was repeatable. Associated phoria testing found both lateral and vertical orthophoria.
The patient was sent for immediate chiropractic evaluation and was diagnosed with clockwise (right) rotation of C2 and C3. She had her cervical spine manipulated and returned within 10 minutes and measured 20/20 in each eye and was orthophoric as indicated by both subjective alternate cover test and Maddox rod. She also reported comfortable and full head and neck motility as well as “clearer vision.”
Cervical, visual misalignment
These cases are a representative sample of at least 30 patients I have treated in my practice with this syndrome. They have in common: a relatively recent onset cluster of symptoms; a minor (less than 1 prism diopter), usually vertical, ocular misalignment; upon specific questioning, patients may report a minor fall or head, neck, back or shoulder injury; and the symptoms as well as the heterophorias resolve with manipulation of the neck.
Many of these patients return for several exams and have no repeatable vertical phorias, some will learn that their symptoms are related to their neck and go directly to the chiropractor, and some have returned and are found to have intermittent, recurrent vertical phorias.
The suboccipital muscles are thought to send proprioceptive feedback to the visual system. I postulate that the mechanism involved in this syndrome is subluxation of the upper cervical vertebrae, which causes the associated suboccipital muscles (primarily the rectus capitis and obliquus capitis groups) to feed inaccurate proprioceptive information to the midbrain with regard to head posture. In other words, the head thinks it is tilted and generates compensatory changes in eye posture, resulting in these small vertical heterophorias.
These proprioceptive inputs likely conflict with those from the vestibular system. The symptoms of this syndrome and benign paroxysmal positional vertigo can overlap. Measurement of small vertical heterophorias can steer the astute clinician to appropriately choose between referral for cervical spine assessment and treatment or vestibular evaluation and therapy.
It may be important to consider this phenomenon when evaluating patients having sustained mild traumatic brain injuries. Careful optometric measurement of vertical heterophoria and cervical alignment might benefit these patients.