Functional Eye Disorders and Malingering

What are the two types of functional (nonorganic) disorders?

Malingering and Conversion Disorder.

What is malingering?

A CONSCIOUS, willful misleading of symptoms for a consciously desired end; patients tend to exaggerate symptoms ("blinder than the blind") and are often irritable and combative.

What is conversion disorder?

Also known as hysteria or psychogenic disorder — a SUBCONSCIOUS expression of symptoms without organic findings, often triggered by psychological stress or physical trauma; patients are typically indifferent to the affliction and usually cooperative.

How do malingering and conversion disorder differ in patient demeanor?

Malingerers are often irritable and combative; conversion disorder patients are usually cooperative and indifferent to their affliction ("la belle indifférence").

Why is observation useful in suspected total binocular blindness?

True blindness is rare; the truly blind patient moves cautiously, while the malingerer often goes out of their way to bump into things.

What does an intact direct and consensual pupillary response tell you?

It excludes anterior visual pathway disease.

What is the menace reflex?

Blinking in response to a visual threat.

What happens with sudden strong illumination in a sighted vs. blind patient?

It induces reflex tearing.

How can signing one's name help detect functional blindness?

The truly blind have no difficulty signing their name; the functionally blind will sign with exaggerated illegibility.

Why is the "touch index fingers together" test useful?

It relies on proprioception, not vision, so a truly blind patient can perform it easily — inconsistent performance suggests malingering.

Why is optokinetic nystagmus (OKN) testing useful in suspected blindness?

OKN is a reflexive response that is difficult for a malingerer to voluntarily suppress.

What is the mirror tracking test for binocular blindness?

A large mirror is rocked back and forth in front of the patient; the eyes will move in response if the patient is not truly blind.

What electrophysiological test can objectively assess vision in suspected binocular blindness?

VECP (Visual Evoked Cortical Potential) — used to check size/acuity thresholds.

Is total monocular or binocular "vision loss" more common in malingering?

Monocular loss is more common; malingerers typically feign monocular loss.

How can tests from the binocular battery be adapted for suspected monocular blindness?

Any binocular test can be performed monocularly.

Describe the Diplopia Test for monocular blindness.

Occlude the poor eye, induce monocular diplopia in the good eye using the base of a strong prism bisecting the pupil (patient should report monocular diplopia in the good eye). Then open both eyes and place the prism fully over the good eye — if the patient still reports diplopia, this indicates malingering.

Describe the 10 prism diopter (PD) test for monocular blindness.

Place 10PD base-out in front of the normal eye and look for version/vergence movement. Place 10PD in front of the "blind" eye — this should produce no movement in either eye if the patient is truly blind in that eye.

What is the Vertical Bar Ruler test (at 5 inches)?

A vertical bar ruler is placed in front of both eyes; a truly monocular person will shift gaze to read text in what would be their "blind" field, while a binocularly sighted person will read across without difficulty.

Describe the Fixation Test using prism.

Related to the 10PD tests — checks for version and vergence eye movements to confirm functioning vision in the suspected eye.

Describe the Plus Fogging Test.

Using the phoropter, the patient reads the eye chart while progressively more plus power is added to the "good" eye; the final line the patient can still read is equal to the true visual acuity of that eye.

Describe the Crossed Cylinder Technique.

Place two cylinders (plus and minus of the same power) at axis 90 and 180 in front of the good eye; while pretending to adjust, switch the axis of one cylinder to 45° (which fogs the good eye); if the patient keeps reading down the chart despite this fogging, it indicates the "poor" eye is actually being used.

Describe the Cycloplegic Test for suspected monocular blindness.

Instill cycloplegic drops in the good eye and artificial tears in the "poor" eye, then have the patient read at near — if they can still read well despite cycloplegia in the good eye, the "poor" eye is functioning.

How is Red-Green Duochrome used to detect monocular malingering?

Project red and green letters; if the patient can read letters on both the red and green backgrounds, the suspected (claimed blind) eye is being used.

How are Red/Green anaglyphs and the Worth 4 Dot test used?

Check the number of dots the patient reports seeing — this can reveal whether both eyes are actually functioning together.

How are Polaroid lenses and vectographic slides used to detect monocular malingering?

If the patient reads an entire line, both eyes must be being used, revealing functional vision in the "blind" eye.

What stereo acuity threshold corresponds to approximately 20/20 vision?

40 seconds of arc of stereo acuity reflects about 20/20 acuity — good stereo acuity implies good vision in both eyes.

How is the "Diminished Vision" technique performed on an acuity chart?

Start at the 20/10 line and suggest to the patient that even 20/15 is huge/difficult; proceed slowly up the chart until the patient actually reads a line, revealing their true acuity.

What is the Visual Angle technique for detecting malingering?

Vary test distances using Snellen, Landolt C, and Tumbling E charts — a patient with genuinely reduced acuity should get the same acuity regardless of test distance (since visual angle subtended is what matters); inconsistent results suggest malingering.

How can Plano Lenses be used to detect malingering?

Place combinations of lenses in a trial frame that add up to net plano power, framed to the patient as "increasing magnification" — if acuity improves with lenses that have no actual refractive effect, this suggests a functional component.

What is Hysterical Visual Field Loss, and what are its classic patterns?

Tunnel vision that does NOT expand with increasing test distance (unlike organic field loss); monocular hemianopia that persists even when retesting binocularly; inconsistent, non-repeatable Humphrey visual field defects.

What Goldmann visual field patterns suggest a nonorganic cause?

Spiraling isopters and crossing isopters.

What is Voluntary Nystagmus?

Irregular brief bursts of rapid frequency, low amplitude horizontal pendular eye movements, which may be associated with eyelid flutter, convergence, blinking, and facial contraction; causes oscillopsia; difficult to maintain for longer than 10-20 seconds.

What is Voluntary Blepharospasm?

A unilateral or bilateral condition that may resemble ptosis or true blepharospasm, but is under voluntary/functional control.

What is Hysterical Asthenopia?

Painful sensations in and around the eyes with inability to read even with the best refractive correction and muscle balance; associated with lacrimation and photophobia.

What is Voluntary Gaze Palsy, and how is it distinguished from an organic gaze palsy?

A rare condition involving limitation of up-gaze (must rule out dorsal midbrain syndromes) or paralysis of horizontal gaze; distinguished from organic palsy by intact Doll's head reflex, intact OKN, and intact mirror tracking.

What are Hysterical Chromatopsia and Micropsia?

Functional disturbances of color perception (chromatopsia) or perceived object size (micropsia) without an organic cause.

What is Munchausen's Syndrome (general definition)?

A rare psychological/behavioral condition in which a person fabricates or induces symptoms of illness in themselves; named after Baron Munchausen, a German aristocrat known for telling wild, unbelievable tales.

What defines Ocular Munchausen's Syndrome?

Deliberate deception, a fabricated medical history, self-inflicted physical abnormalities, and self-inflicted mutilation; a mental health evaluation is mandatory.

What organic conditions are commonly mistaken for functional vision loss?

Keratoconus, amblyopia (strabismic or anisometropic), macular diseases (early Stargardt macular dystrophy, central serous chorioretinopathy, cystoid macular edema), cone dystrophy, and retinitis pigmentosa sine pigmento.

How is keratoconus ruled in/out as a cause of apparent functional vision loss?

Biomicroscopy and K-readings (keratometry).

How is amblyopia identified as the true cause?

Look for underlying strabismus or anisometropia.

How are macular diseases evaluated when functional loss is suspected?

Careful macular examination and fluorescein angiography.

How are cone dystrophy and retinitis pigmentosa sine pigmento diagnosed?

Electroretinogram (ERG).

What is Accommodative Spasm, and how does it present?

A common condition with intermittent episodes of convergence, miosis, accommodation, and myopia; pupil constriction occurs on attempted lateral gaze; Doll's head is normal; presents with diplopia and micropsia.

How is Accommodative Spasm treated?

Patching or cycloplegia can help; treatment is generally difficult — options include atropine or medial rectus botulinum toxin injections.

What optical causes can produce Monocular Diplopia?

Irregular astigmatism, keratoconus, tilted lens, cataracts, macular cysts, epiretinal membrane, central serous chorioretinopathy.

How do you differentiate optical monocular diplopia from a nonorganic cause?

A pinhole eliminates optical causes; contact lenses are often very successful in eliminating monocular diplopia when optical in origin.

What rare neurologic causes can produce monocular diplopia or polyopia?

Pituitary tumor, occipital cortex tumor or hemorrhage, frontal eye field lesions, cerebral polyopia.

What is the primary approach to treating functional disease?

Reassurance, emphasizing things the eyes do well; avoid confrontation, which is unproductive.

Why should eye drops, eye exercises, or spectacles generally be avoided in functional disease?

They undermine the reassurance approach and draw further attention to the eyes.

What is recommended alongside reassurance in managing functional disease?

A mental health consult, in collaboration with the patient's primary care provider (PCP).

What is "Retinal Rest," and when might it be used?

Hospitalization with bilateral patches and sensory deprivation — no radio, TV, or visitors — used as a treatment approach for functional visual disease.

Why is it important to be cautious when diagnosing a patient with a nonorganic/functional disorder?

Patients with non-organic disorders may still have coexisting organic disease — a "functional" label does not rule out real pathology.

In the study of 85 patients diagnosed with "hysteria," what were the outcomes?

22 had coexisting organic disease, 2 had schizophrenia, 4 committed suicide, and 8 died of organic disease that was present at the time of their "hysteria" diagnosis — a total of 36 out of 85 patients had a serious missed or coexisting condition.

What is the key takeaway/caution from this data?

"We diagnose only in the limited universe in which we explore" — a functional diagnosis should not end the diagnostic workup, since serious organic or psychiatric disease may coexist or be missed.