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Thyroid Disease and the Eye: What We Must Know
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The endocrine system
A Goal- maintaining homeostasis
1 Organisms are exposed to constant change
2 The ability to respond to change is inherent in living things
3 Maintenance of homeostasis is vital to survival!
4 Homeostasis is the job of the of the endocrine system
B Communication and homeostasis
1 Some situations require rapid, focal response (nervous system)
a Speed is the critical issue
b Resources used are of minimal importance
2 Some situations require slower, widespread response (endocrine
system)
a Speed not the critical issue
b Reaching a very large number of target tissues is crucial
c Resources need to be conserved
3 Selectivity-To affect a target cell receptors specific for a given
hormone must be present
a Cells lacking receptors to a specific hormone will not react to it,
regardless of concentration
b Hormonal selectivity is crucial to proper functioning of the
endocrine system
4 Hormone glands and functions
a Hypothalamus – region not gland
I Releasing hormones
II Inhibiting hormones
b Pituitary gland
I Hormones reach circulation & act on:
II Other glands
III Target organs
c Adrenal glands-cortisol
d Gonads- sex hormones
e Thyroid
I Hormones that can affect entire body
II Parathyroid- parathyroid hormone
f Pancreas- insulin, glucagon
5 Thyroid produces thyroxine (T4)= 90% and triiodothyronine (T3)=10%
6 Liver, kidneys convert T4 to the more powerful & rapidly acting T3
7 Thyroid hormones increase:
a Heart rate
b Body temperature
c Mood, alertness
d Protein production
e Lipid metabolism
f Overall metabolic rate
8 Thyroid gland anatomy, physiology
a Butterfly shaped gland located on anterior larynx
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b Follicles- sub-units that produces thyroid hormones
I Each follicle filled with colloid, site of thyroid hormone synthesis
II Follicles richly supplied by fenestrated capillaries
9 Biosynthesis of thyroid hormones
a TSH reaches follicle via circulation- stimulates hormone biosynthesis
b Follicle epithelial cells transport iodide into colloid
c Thyroglobulin binds iodide to form T3 & T4
d T3 & T4 released into circulation – act on target organs-produce
desired effects
10 Functions of thyroid hormones
a Increase basal metabolic rate
b Stimulate fat mobilization
c Increase concentrations of fatty acids in plasma
d Lower cholesterol
e Stimulate carbohydrate metabolism & protein synthesis
f Increase heart rate, cardiac contractility and cardiac output
g Increase alertness, positive mental state
Thyroid diseases
A Risk factors
1 Gender: women
a Five to eight times more likely to suffer from a thyroid disorder
b Higher risk of developing a thyroid disorder with increasing age
2 Age:
a Individuals over 50 have the highest risk of thyroid disease
b Male risk of developing thyroid disease increases after age 60.
3 Radiation exposure - head and neck region during childhood
increases the risk of thyroid disease.
B Hypothyroidism
1 Second most common endocrine disorder in the United States
2 Thyroid gland produces reduced levels of thyroid hormones
3 Body functions at a lower metabolic rate.
4 Can contribute to heart disease
5 Increased amount of LDL (bad) cholesterol
6 Hashimoto’s Disease
a Autoimmune disease first described in 1912 by Dr. Hakaru
Hashimoto
b The immune system attacks & ultimately destroys thyroid gland
c Gender: 5-10 times more common in women
d Histological findings
I Thyroid-specific lymphocytes attack & infiltrate the thyroid
II Lymphoid cellular infiltration
III Follicular epithelial cell destruction
e Signs, Symptoms
I Fatigue
II Depression
III Modest weight gain
IV Cold intolerance
V Excessive sleepiness
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VI Dry, coarse hair
VII Constipation
C Hyperthyroidism
1 Thyroid gland produces excessive T3 & T4
2 Increases metabolic rate of the body
3 Symptoms & complications of hyperthyroidism
a Nervousness
b Decreased menstrual flow
c Weight loss
d Irregular heartbeat
e Infertility and miscarriage
4 Graves’ Disease- autoimmune disease affecting thyroid gland
metabolism
a First described 1835-Dr. Robert Graves
b Triad of:
I Goiter- swelling of thyroid gland
II Exophthalmos
III Hyperthyroidism
c Most common cause of hyperthyroid and diffuse goiter
d Plasma cells make antibodies to the thyroid-stimulating hormone
receptor (TSHR)
e Auto-antibodies not subject to negative feedback
f Unlimited thyroid hormones are produced, released into circulation
III Thyroid associated eye disease (TAED)
A 20% of patients state ocular morbidity troublesome than thyroid disease
B Dry eye (with hyperthyroid and hypothyroid)
1 Gilbard JP, Farris RL. Ocular surface drying & tear film osmolarity in
thyroid eye disease. Acta Ophth 1983
a Evaluated 17 patients w/ Graves’ DZ
b 94% had dry eye symptoms
c 42% had increased tear film osmolarity
d Increased palpebral fissure width
e Rose bengal staining proportional to PFW
f Increased blink rate associated w/ Rose bengal staining
2 Management
a Well designed artificial tears
I Goebels & Spitzmas- NO BAK
II Blink Tears- CMC based, comfort excellent, duration issues?
III Soothe- lipid component for reduction of evaporative dry eye
IV Systane Balance- lipid component present up to 90 minutes
b Punctal occlusion
I Positive prognostic indicators
II Moderate to adequate aqueous layer
III Minimal inflammatory indicators
IV Anterior blepharitis and or posterior blepharitis
V Meibomian gland & lid margin scarring
c Negative prognostic indicators
I Minimal to no aqueous layer
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II Significant inflammatory indicators
III Anterior blepharitis and or posterior blepharitis
IV Meibomian gland & lid margin scarring
V Lid configuration issues
VI Punctal ectropion
d Restasis- Excellent therapy for thyroid-associated dry eye
A Expect a three month lag between TX & improvement
B Prescribe for optimal financial benefit
C Ophthalmopathy
1 Upper lid retraction (Dalrymple sign) #1 sign
2 Proptosis- sympathetic drive of Müller muscleCompressive neuropathy
a Increased surface area > drying
3 Visual field loss
4 Diplopia
a Upgaze restriction- fibrosis of the levator
b Estropia- fibrosis of medial rectus
c Contralateral ptosis (myasthenia)
D Management/Triage
1 Lid evaluation at office visits
2 EOM evaluation, history of diplopia
3 Proptosis, EOM changes
a May change significantly over time
b Obtain (and bill for) baseline photos for future reference
c Work with a competent and conservative lid specialist
d Protect the anterior surface from dryness secondary to exposure
4 Surgical options
a Botulinum toxin injections
I Duration @ 3 months-40 months
II Complications- ptosis, diplopia
b Surgery
I May use weights or relaxing procedure to reduce lid lag
II Delay consultation until stable
IV Thyroid-associated ophthalmopathy
A Definition
B Pathogenesis
1 Lymphocytic infiltration of orbital tissue  release of cytokines i.e. IL-1
2 Cytokines activate quiescent fibroblasts, secrete hyaluronic acid
3 Doubling hyaluronic acid content 5-fold increase in osmotic load
4 Osmotic damage results in muscle edema
5 May occur despite well controlled hyperthyroidism
6 Usually a self-limited course over one or more years.
7 Strongly associated with smoking
C Treatment options
D Goals of therapy
1 Cosmetic (disfiguring proptosis, exophthalmos, strabismus)
2 Functional (reduce dryness, diplopia)
3 Sight preservation (compressive optic neuropathy)
4 Approx 5% of TAO patients require surgery
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Orbital decompression
a Surgery generally delayed until after the inflammatory phase
b May be forced to operate sooner if vision loss is present
c Two orbital walls decompressed
I Traditional: the medial wall and floor of the orbit
II Decompression of the medial & lateral orbital walls is gaining
popularity
d Three walls orbital decompression increasingly common
a Delay until patient is stabilize
V The optometrist’s role in thyroid associated ocular conditions
A Detection
1 High index of suspicion especially in females
2 Recent onset severe dry eye no other
3 Weight gain, loss, pretibial edema
4 Changes in mentation, personality
5 Obvious changes in lids, adnexae
B Consultation when indicated
1 Internist or endocrinologist
2 Send reports after your visits: (Forms in MS Word)
C Long-term care, reassurance, remediation
VI Conclusion
A OD’s may be the first health care providers with the opportunity to detect
thyroid disease
B ODs may be the first health care providers to diagnose TAED
C Management of most patients with these conditions within our scope and
expertise
D Have an index of suspicion for any patient who presents with the diverse
signs & symptoms of TAED