I am surprised at how many requests I have gotten for my paper on
Neuro-Ophthalmology and PD.  I'll take Camilla's suggestion and divide it
into 2 parts to fit on the LISTSERV.

PART I


NEURO-OPHTHALMOLOGIC MANIFESTATIONS OF PARKINSON'S DISEASE

Jacqueline M.S. Winterkorn, Ph.D., M.D.
 New York, New York

1. INTRODUCTION - DEMOGRAPHICS
Parkinson's disease [PD] is known to affect over 1 million Americans and its
diagnosis is becoming increasingly common, including 50,000 new patients per
year26.  Some epidemiologic studies involving door-to-door canvassing suggest
underdiagnosis by as much as 25%14.  In the over-60 population, the incidence
is 1-2%.  Despite the common myth that Parkinson's affects only the elderly,
in fact the average age of symptom onset is 57, with over a third of all
victims starting symptoms in their 20's, 30's, and 40's.  PD is characterized
by tremor, rigidity, bradykinesia, and impaired balance26.  Most patients
with Parkinson's disease [PD] develop some ophthalmic complaints, e.g.
blurred vision, double vision, photophobia, asthenopia, or trouble reading.
As many as 75% of PD patients have oculomotor signs10.  PD is mainly a motor
disorder, caused by death of dopaminergic neurons in the substantia nigra
compacta, leading to loss of dopamine in the putamen. The depletion of
dopamine from the other regions of the brain, especially from the visual
cortex6 and from amacrine and interplexiform cells of the retina16, 30 in
patients with PD has prompted studies looking for visual perceptual
abnormalities19.
 It behooves us as neuro-ophthalmologists to know the eye signs of PD, which
ones the patients complain about, and what relief or management can be
offered.

2. NEURO-OPHTHALMIC DEFICITS
 Lawton Smith described an acrostic for PD problems 36, 37, which I present
here with modifications.

Pareses of gaze-- Clinical observations of patients with PD have described
slow, hypometric saccades and incomplete upgaze10. A differential response to
an optokinetic stimulus in the horizontal and vertical plane has been
described, with OKN present in the horizontal plane, but absent or
poorly-formed vertically 36, 37. These old studies may reflect the high
prevalence of post-encephalitic PD at that time. Although vertical gaze
abnormality has been associated with PD, limited upgaze to command is common
in older people33 and may be a non-specific defect.  Moreover, the eye
movement disorder characteristic of idiopathic PD is mild and may not be
apparent in the early stages of PD or in patients well-controlled by
levodopa39.
Pursuit gain is decreased, leading to jerky pursuit, referred to as
"cogwheel," since reminiscent of the ratchety limb movements in PD10,  41.
Saccades to novel stimuli usually remain unaffected, with normal latency,
peak velocity and duration 11.  However, saccades that are made not to an
actual visual stimulus, but rather to a remembered location, or repeated
predictive saccades tend to be dysmetric11.  These saccades are hypometric,
show delayed initiation, and may be slowed34.  In patients with hypometric
saccades, saccadic amplitude has been shown to normalize after a dose of
L-dopa. In patients having Levodopa-induced dyskinesias, eye movements may
become more frequent and saccades hypermetric.
  Imbalance and postural instability are reflected in poor stabilization of
images and impaired eye-head coordination 38, 41.  Head movements may also
become smaller and slower than normal.
If saccades are dramatically slow or downgaze is severely impaired, the
diagnosis of idiopathic PD should be questioned39.  Parkinson's Plus
syndromes should be differentiated from idiopathic PD, by severity of eye
movements abnormalities. Disorders such as Progressive Supranuclear Palsy
[PSP], cortical-basal ganglionic [corticobasal] degeneration and
olivopontocerebellar atrophy show far more severe eye movement deficits.  For
example, the eye movements of PSP are characterized by numerous square wave
jerks, very slowed saccadic speeds, and supranuclear vertical
ophthalmoplegia, with early absence of downgaze12, 13.  These signs do not
respond to L-dopa.

Accommodative paresis -- Accommodative insufficiency is a common problem in
people with PD, causing diplopia and difficulty with reading1, 33.
Difficulties with accommodation also can result from medications, especially
the anticholinergics [e.g. Artane, Cogentin, benedryl] given to control
tremor.   Normal  convergence amplitudes with a distant near point can be
demonstrated.  Convergence insufficiency has been described as a consistent
abnormality, contributing to asthenopia or diplopia at near33.  Less often,
divergence insufficiency leads to diplopia in the distance.

Reflex Blepharospasm and Blepharoplegia-- Eyelid abnormalities including
blepharospasm and apraxia of eyelid opening and  low blink rate are typical
in PD1.  Inability to open the eyes in a person with PD may be caused by [1]
blepharospasm, either reflexive or essential,  [2] apraxia of eyelid opening,
 [3] diplopia avoidance, or  [4] dry eyes.  Both  Essential Blepharospasm and
apraxia of eyelid opening have been associated with postencephalitic-PD42 and
PSP.  Frontal lobe activity may be abnormal35.
Having PD does not exempt a patient from common eye diseases such as cataract
and glaucoma. However, blepharospasm makes examination for these conditions
especially difficult, for example, by interfering with obtaining intraocular
pressure by applanation.

Keratitis Sicca -- Dryness of the cornea is the result of autonomic
dysfunction, exacerbated by medications1.  Seborrheic dermatitis affecting
the lids and face is common, especially in patients with compromised hygiene.
 Tear secretion is reduced with abnormal composition,  and chalazia may
develop.    A poor tear film also results from infrequent blinking24.  Eye
pain and blurred vision frequently are caused by corneal surface
abnormalities.

Infrequent Blinking -- Infrequent blinking contributes to the wide-eyed
expressionless stare characteristic of PD.  Hypokinesia of the levator make
the lids appear retracted. The blink rate may be as low as 1-2 per minute [nl
16-18 per minute]24.  This complicates management of the dry eye syndrome.

 No hemianopsia-- except after pallidotomy. Visual fields have not been shown
to be abnormal in patients with PD, except after surgical procedures, such as
pallidotomy.  In the early years of this surgery, as many as 40% of patients
were left with contralateral homonymous hemianopsias resulting from
involvement of the optic tract in the lesion intended for the adjacent ansa
lenticularis. Today, even with advanced neurosurgical methods of recording
VEPs in order to avoid lesioning the optic tract, pallidotomy surgery still
results in contralateral superior quadrantanopsias in 5-10% of patients4.

Sensory Abnormalities --  Although many studies of visual perception have
documented abnormalities, few clinical correlates are apparent 28.  [See
TABLE]  Visual acuity may be slightly decreased in PD patients compared with
controls 23 ,33 but more often it is normal after careful refraction and
corneal wetting.  Performance has been impaired on some more complex sensory
tests.  Contrast sensitivity [CS] is abnormal 8, 25, especially the form of
the CS curve 6, 7, 8. This reflects diminished CS at intermediate and high
frequencies, with relative absence of the low frequency drop-off.  Similarly,
latency of the VER is delayed to sinusoidal gratings of medium to high
spatial frequency 5, 25. This has been interpreted as an indication that
retinal dopaminergic cells are involved in refinement of center-surround
receptive field organization7. The finding that the CS abnormality is greater
for horizontal than for vertically-oriented gratings was interpreted to
implicate cortical function, since orientation selectivity is a property of
cells in the visual cortex 40. However, this might also reflect paucity of
eye movements affecting viewing of the gratings.  The degree of delay is
correlated with motor impairment, with improvement shown after L-Dopa 20, 25,
29.
     Poor performance on color discrimination has been reported, not improved
by medication 2, 9, 32.  Color vision in the blue/yellow axis seems
particularly affected18.   Pattern ERG's  show decreased amplitudes17, 29, 31.
 Temporal functions have been ascribed to amacrine cell abnormalities.
Flicker thresholds are impaired 7. Decreased motion detection has been
reported. Simple visual attention is normal, but more complex tasks may be
affected3.
Hallucinations are common in patients with PD, occurring in 25-40% of
patients. Patients who experience hallucinations are usually older, have poor
vision, or are receiving medications. As many as 10% may also have auditory
hallucinations21 .

Oculogyric Crises -- This unusual ocular deviation was a hallmark of
postencephalitic Parkinson's (common after the pandemic influenza outbreak of
1916-1930) and is rarely seen nowadays except as a side-effect of neuroleptic
drugs. It consists of an uncomfortable forced upward or up-and-lateral tonic
deviation of the eyes42.

No Nystagmus or Dementia -- Nystagmus is not seen in idiopathic PD in
contrast to postencephalitic PD, where it was common. Dementia is not found
in young-onset PD patients. In elderly patients with PD, dementia is present
far more often than in controls.

Signs -- Meyerson's sign is the failure of the blink reflex to habituate to
repeated glabellar tap.
Wilson's sign is the need to blink in order to change saccadic direction.