A PRACTICAL APPROACH TO UNEXPLAINED VISUAL LOSS
From the Annual Clinical Conference, presented by the Kansas City Society of Ophthalmology and Otolaryngology
Karl C. Golnik, MD, Professor, Departments of Ophthalmology, Neurology and Neurosurgery, University of Cincinnati
College of Medicine and the Cincinnati Eye Institute, Cincinnati, OH
Educational Objectives
| The goal of this program is to improve the diagnosis and management of unexplained visual loss. After hearing and
assimilating this program, the clinician will be better able to:
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 | List common evaluation tools that are effective in diagnosing an underlying refractive or media problem.
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| Explain the usefulness of color vision testing in identifying the cause of vision loss.
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| Recognize the clues in a patient’s history and signs on examination that suggest an underlying retinal or choroidal
problem, and select an ancillary test that will be helpful in establishing the diagnosis.
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| Discuss the different perimetric strategies for testing the patient’s visual field (VF), and explain the importance
of choosing the correct VF test.
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| Describe some of the techniques that can be used to identify the patient with a nonorganic visual problem.
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Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the
planning committee to disclose relevant financial relationships within the past 12 months that might create any personal
conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes
quality in health care and not a proprietary business or commercial interest. For this program, Dr. Golnik and the
planning committee reported nothing to disclose.
Acknowledgements
Dr. Golnik spoke at the Annual Clinical Conference, held January 9-10, 2009, in Kansas City, MO, and sponsored by
the Kansas City Society of Ophthalmology and Otolaryngology. The Audio-Digest Foundation thanks Dr. Golnik and
the Kansas City Society of Ophthalmology and Otolaryngology for their cooperation in the production of this program.
Refractive or Media Problems
| Case 1 (drinking dentist): 60-yr-old man; complains of gradual bilateral blurriness; medical history—hypertension;
one alcoholic drink/day; previously diagnosed with tobacco-alcohol amblyopia and advised to stop drinking (wanted second
opinion); on physical examination—visual acuity (VA) 20/60 both eyes (OU); near vision (NV) Jaeger(J) 2 OU;
color vision (10/10 Hardy-Rand-Ritter [HRR] color plates OU); pupils moderately reactive; no relative afferent pupillary
defect (RAPD); visual field (VF) and fundus normal; question—are these findings compatible with previous diagnosis?
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| Refractive or media problems: occult refractive or media problems that may account for unexplained visual loss include
irregular astigmatism, oil-droplet cataracts, and occult corneal disease; common tools for evaluation—pinhole; NV
(disparity between distance vision [DV] and NV indicates media or refractive problem); retinoscopy/corneal topography;
rigid contact lens over-refraction (good substitute for corneal topography); direct ophthalmoscopy (best way to diagnose
media problems); color vision testing can be very helpful (color vision not affected by refractive or media problems, unless
patient’s VA very bad); HRR color plates more sensitive, and speaker prefers to use them if VA near 20/25 to 20/40;
in cases in which patient’s VA 20/50 or worse, speaker uses Ishihara plates interchangeably with HRR)
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| Comments: findings from patient’s examination do not support diagnosis of tobacco-alcohol amblyopia (color vision
and disparity between NV and DV suggest condition other than optic neuropathy); further testing—direct ophthalmoscopy
(blurred view); potential acuity meter (20/20 OU); diagnosis—oil-droplet cataracts identified on repeat slit-lamp
examination (SLE)
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Retinal or Choroidal Issues
| Case 2 (disabled secretary): 49-yr-old woman complains vision (NV and DV) becomes blurry after reading; on
examination—initially, VA 20/20 OU; NV J1+ OU, examination otherwise normal; after reading for 30 min, patient’s VA
20/30 OU and NV J2 OU; vision returns to baseline 20 min after patient stops reading; corneal topography done before
and after reading (difference map shows induced change in curvature of cornea); speaker and colleague have reported on
3 patients with this problem; all wore bifocals; diagnosis—problem appears to be caused by pressure (presumably of
lower eyelid) on cornea, resulting from prolonged reading in downgaze; treated by switching patients to full-field readers
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| Retinal or choroidal issues: patient history can be important (when patient uses terms like “distorted” or “crooked” to
describe vision [metamorphopsia], speaker suspects occult retinal problem); tiny central scotomas more often retinal than
central nervous system (CNS) issue; on examination, patient with retinal or choroidal problem should have no or small
RAPD; Amsler grid helpful diagnostic tool; ancillary tests, eg, fluorescein angiography (FANG), indocyanine green
chorioangiography (ICG), optical coherence tomography (OCT), electroretinography (ERG), also helpful
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| Case 3 (peripheral vision loss after colonoscopy): 57-yr-old woman; history—hypertension; lung cancer; on
examination—VA 20/25 OU; color vision normal; pupils moderately reactive, no RAPD; SLE shows rare anterior vitreous
cell OU; VF poor; fundus (including peripheral retina) appears normal; ERG flat (indicating retinal problem);
diagnosis—cancer-associated retinopathy (CAR)
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| CAR: positive visual phenomena (eg, flashing lights) often prominent; can produce anterior vitreous cells; early on, may
see ring scotomas that lead to peripheral field loss and can ultimately wipe out entire retina; abnormal ERG diagnostic;
tests for antiretinal antibodies available
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Visual Loss Involving Optic Nerve or Visual Pathway
| Case 4 (intermittent spots in vision): 63-yr-old man; has had problem for 3 mo; history—diabetes and hypertension
for 6 yr; patient taking metformin (eg, Glucophage) and amlodipine (eg, Norvasc); on examination—VA 20/20, 20/30 (in
eye in question); pupils brisk, no RAPD; dilated fundus examination normal, except for one small blot (intraretinal hemorrhage
temporal to fovea of left eye [OS]); patient had Hollenhorst plaque; plaque detectable only when digital pressure
applied to eye (speaker offers this as examination technique; digital pressure pushes Hollenhorst plaque into position that
reflects light back; later, after having patient do CO2 rebreathing to dilate pupils, can apply digital pressure to eye to facilitate
migration of plaque downstream); treatment—patient started on aspirin; carotid Doppler ultrasonography (US)
showed minimal plaque in right internal carotid artery and 40% stenosis in left internal carotid artery; follow-up—
treatment with aspirin resulted in no more spots (diagnosed as amaurosis fugax) at 2 mo follow-up
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| Visual loss involving optic nerve or visual pathway: RAPD—patient presenting with unexplained visual loss
should have his or her pupils examined by physician (task should not be delegated to technician or resident); test for
RAPD straightforward (requires dark room, bright light, 2 eyes, ≤1 working pupil; have patient fixate at distance target);
color vision testing—also helpful in identifying optic neuropathy; unlike refractive or media problems, in which VA must
be terrible before color vision affected, patient with optic neuropathy can have VA of 20/20 and still miss 50% of color
plates; color vision testing most helpful if one eye good and other eye bad; strategies for testing VF—Goldmann manual
perimetry; automated perimetry (Humphrey visual field [HVF] analyzer [24-2, 30-2, and 10-2 programs]); Amsler grid
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| Case 5 (difficulty reading): 75-yr-old woman; complains of difficulty reading since previous day; history—
hypertension; mild dry age-related macular degeneration (AMD); previous cataract surgery; no other symptoms or problems;
on examination—VA 20/20 OU; color vision good; VF full at confrontation; intraocular lenses (IOLs) in good position;
when asked to clarify “difficulty reading,” patient reports seeing only part of word she is looking at (with both eyes
open); suspected diagnosis—occipital stroke; recommended VF test—HVF 10-2 program (same protocol as HVF 24-2
program, but has smaller grid density; can pick up small scotomas that fit between tested points on HVF 24-2);
conclusion—good example of importance of ordering correctt VF test
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| Case 6 (difficulty reading): 71-yr-old man; has seen 3 physicians and has 5 new pairs of glasses; wife notes patient exhibits
occasional clumsiness; on examination—VA (DV and NV) 20/20 OU; VF normal on HVF 24-2 and 10-2 programs
and Amsler grid; patient asked to read; difficulty appeared to be cognitive (did not demonstrate problem using
vision); patient then asked to describe what he saw in illustration from Boston Diagnostic Aphasia examination;
diagnosis—determined that patient had visual processing problem; diagnosed with visual variant of Alzheimer’s disease
(VVAD)
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| VVAD: not uncommon; may occur in patients with previously diagnosed AD, but sometimes visual symptoms first sign of
AD; 90% of patients with VVAD have difficulty reading; take-home point—when patient complains of difficulty reading,
has normal visual examination, and is in appropriate age range, important to consider cognitive issues and visual
processing; these patients can also have simultanagnosia, spatial disorientation, ocular apraxia, or homonymous VF defects
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Nonorganic Visual Loss
| Case 7 (kicked in eye): 28-yr-old woman; complaint of poor vision OS after being kicked in eye; ocular history—
HLA antigen B27+ uveitis; mild “smoldering” macular edema; baseline vision 20/40 OU; on examination—VA 20/40
in right eye (OD), counting fingers OS; no RAPD; fundus appears normal on SLE
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| Comments: “nonorganic” encompasses number of other terms (eg, malingering, Munchausen, conversion disorder, hypochondriac);
however, these terms psychiatric diagnoses, and speaker not comfortable using these, as he does not know
why patient claims to have vision loss (eg, patient may be faking to get disability or attention; could be hypochondriac or
have psychiatric conversion problem); speaker much prefers, and encourages colleagues, to use term “nonorganic” (and
to avoid terms like “malingering”) in notes and when making diagnosis
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| Testing nonorganic visual loss: approach depends on laterality and severity; patients present with different forms of
nonorganic visual problems (usually poor vision in one eye); easy to evaluate patients complaining of severe bilateral,
unilateral, or moderate unilateral vision loss; very difficult in cases of mild to moderate bilateral loss; keep in mind that
patient who appears to have nonorganic visual loss may have true medical problem (do not just dismiss patient)
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| Evaluating severe bilateral vision loss: observe ambulation (watch patient walk through waiting room); sunglasses
proven “red flag” for nonorganic visual loss; optokinetic nystagmus (OKN) drum (before using, first ask whether patient
can see black and white stripes on drum; technique helpful only if patient cannot see stripes); moderate to severe
unilateral visual loss—start with small letters on eye chart (20/10 line); “doctor killing refraction” (DKR) takes too
much time; gradual fogging of patient’s good eye in Phoropter vision tester (so that patient thinks he or she is looking
with good eye when actually looking with bad eye; again, takes time); stereopsis helpful in checking patient who complains
of decreased NV; vertical prism test
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| Vertical prism test: simple; requires patient with asymmetric or unilateral loss of vision; display single letter on Snellen
distance chart that is 1 line higher than best VA in good eye; place 4-prism-diopter (4-PD) prism base-down over good
eye; with both eyes open and best correction, ask patient what he or she sees; if patient being truthful and really has bad
vision in one eye, will only see one letter (depending on VA, may be able to see another chart, but will not be able to
see what is in it); if patient faking, or has nonorganic visual loss, will see 2 letters, one above the other; when speaker
gets this response, he asks patient if letters are approximately the same clarity; if patient responds “yes,” have proven
that eyes have equivalent VA (patients often claim that letter above is slightly clearer, which is in fact image seen by
bad eye); test can be conducted quickly and does not arouse patient’s suspicion because physician not checking patient’s
other eye; if patient with suspected nonorganic vision problem does report seeing only one letter, need to look
very hard for etiology of his or her visual loss
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| Comments: patient from case study did see 2 letters on vertical prism test; doctors reassured her that her eyes looked
good and that her vision would get better; patient called few days later to report vision had returned to normal
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| Case 8 (blurry vision OU): 46-yr-old man; has had problem for 2 mo; referred by retina specialist who noted patient
viewing small pocket calendar; nonorganic visual loss suspected; on examination—VA 20/60 OD, 20/200 OS; no RAPD;
SLE/fundus normal; VF test correlated with findings of visual examination (showed central depression and asymmetry in
VA); on vertical prism test, patient saw only one letter, which indicated patient truly had visual problem; speaker ordered
focal ERG, which showed partial cone dystrophy; patient sent back to retina specialist
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| Case 9 (“clearly blind” man in need of handicapped sticker): 60-yr-old man; referred by retina specialist; patient
reports having had poor vision since childhood; walks with cane “and clearly he’s blind”; history—hypertension;
recently released from prison after 25 yr; on examination—VA hand motion OU; pupils briskly reactive, no RAPD; VF
(sees motion in all quadrants); fundus and ERG normal; speaker’s supposition that fact that patient partially cortically
blind could account for results of examination and tests; however, speaker also suspicious that something else going on;
ways to evaluate whether patient’s vision as bad as claimed include observing patient’s ambulation and performing OKN
drum test (which, in this case, showed nystagmus); speaker now knew patient had at least one component of nonorganic
visual loss, but this did not mean VA 20/20 (person can have VA of 20/400 and still develop OKN nystagmus); speaker requested
patient’s MRI records from prison; after patient returned to sign release forms, speaker’s assistant observed patient
walk across parking lot with cane, get into driver’s side of car, and drive away; assistant surmised all patient wanted
was handicapped parking sticker; speaker looked at website, and discovered patient had been in prison for first- and second-degree
murder; he issued patient handicapped sticker and never saw him again
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| Concluding statements: when evaluating patient with unexplained visual loss, must first determine where problem located
(ie, is it front of eye, back of brain, somewhere in between, or not physical problem [ie, nonorganic]); use common
diagnostic tools (eg, color vision testing, direct ophthalmoscopy); obtain correct visual field test; must prove (not just suspect)
that patient has nonorganic loss of vision; advantage of vertical prism test is that one can not only prove problem is
nonorganic but that patient has very good vision
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Suggested Reading
Bengtzen R et al: The "sunglasses sign" predicts nonorganic visual loss in neuro-ophthalmologic practice. Neurology
70:218, 2008; Buono LM et al: Unexplained visual loss. Surv Ophthalmol 48:626, 2003; Goetgebuer G et al:
Cancer-associated retinopathy (CAR) with electronegative ERG: a case report. Doc Ophthalmol 116:49, 2008;
Golnik KC, Eggenberger E: Symptomatic corneal topographic change induced by reading in downgaze. J Neuroophthalmol
21:199, 2001; Golnik KC et al: The monocular vertical prism dissociation test. Am J Ophthalmol
137:135, 2004;
Griffiths PG, Ali N: Medically unexplained visual loss in adult patients. Curr Opin Neurol 22:41, 2009; Griffiths
PG, Eddyshaw D: Medically unexplained visual loss in adult patients. Eye 18:917, 2004; Heher KL et al: Oil-
drop cataracts. J Cataract Refract Surg 19:306, 1993; Leavitt JA: Diagnosis and management of functional visual
deficits. Curr Treat Options Neurol 8:45, 2006; Lee AG, Martin CO: Neuro-ophthalmic findings in the visual variant
of Alzheimer's disease. Ophthalmology 111:376, 2004; McBain VA et al: Assessment of patients with suspected
non-organic visual loss using pattern appearance visual evoked potentials. Graefes Arch Clin Exp Ophthalmol 245:502,
2007; McCulley TJ et al: The effect of decreased visual acuity on clinical color vision testing. Am J Ophthalmol
141:194, 2006; Murtha T, Stasheff SF: Visual dysfunction in retinal and optic nerve disease. Neurol Clin 21:445,
2003; Reddy AR, Backhouse OC: Medically unexplained visual loss. Eye 20:859, 2006; Renner AB et al: Recording
of both VEP and multifocal ERG for evaluation of unexplained visual loss electrophysiology in unexplained
visual loss. Doc Ophthalmol 111:149, 2005; Scott JA, Egan RA: Prevalence of organic neuro-ophthalmologic disease
in patients with functional visual loss. Am J Ophthalmol 135:670, 2003; Shindler KS et al: Functional Visual
Loss. Curr Treat Options Neurol 6:67, 2004; Zinkernagel SM, Mojon DS: Distance doubling visual acuity test: A
reliable test for nonorganic visual loss. Graefes Arch Clin Exp Ophthalmol Epub: Dec 17 2008.
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