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Table of Contents
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1. Introduction
2. Diabetic disease
o 2.1 Screening for diabetic retinopathy
o 2.2 Treatment of diabetic retinopathy
3. Sickle cell anaemia
4. Hypertension
o 4.1 Arteriolar sclerosis
o 4.2 Elevated blood pressure
o 4.3 Screening for hypertensive retinopathy
5. Inflammatory conditions
6. Systemic infections
7. Thyroid disease
8. Myasthenia gravis
9. Cancer and the eye
References
1. Introduction
An understanding of the significance and implications of ocular presentation of systemic
disease is vitally important in primary care practice.
Some patients suffering from systemic disease are at particular risk of ocular complications,
many of which are sight threatening. General practitioners play an important role in ensuring
that these patients have regular ophthalmic review. Diabetes, hypertension and autoimmune
disorders in particular predispose patients to complications.
Golden Rule!
Patients with systemic infections or autoimmune diseases presenting with red eye,
decreased vision, photophobia or floaters should be referred ASAP to look for
intraocular inflammation.
Systemic disorders may present initially with ocular symptoms and signs. An awareness of
the possible presentations of systemic disease is essential to diagnosis.
Golden Rule!
Remember, rare diseases present to common doctors.
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2. Diabetic disease
Eye disease resulting from diabetes mellitus is the predominant cause of onset of blindness
from the ages of 25-74 years. Only 2/3 of high risk diabetic retinopathy patients receive
adequate care. 21-36% of people suffering from diabetes mellitus have retinopathy (6-13%
have vision threatening retinopathy).
Diabetes, hypertension and atherosclerosis are the most common causes of III and VI nerve
palsies and the second most common cause (after trauma) of IV nerve palsy. III nerve palsy
presenting with periorbital pain may in fact be the first clinical sign if diabetes and further
diagnostics (eg blood glucose) are warranted. Trauma, aneurysms, neoplasms and
inflammation may also cause nerve palsies.
Diabetic retinopathy risk factors
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Duration of diabetes
- Type 1 (IDDM) sufferers are retinopathy free for the first 5 years or to puberty, after
that retinopathy increases with time.
- Type 2 (NIDDM) sufferers also demonstrate increased retinopathy with duration of
diabetes. 10-15% present with significant retinopathy at diagnosis.
Poor glycaemic control
- Good glycaemic control in IDDM patients has been shown to have a significant
effect in reducing retinopathy risk.
Hypertension
Hyperlipidaemia
Nephropathy
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2.1 Screening for diabetic retinopathy
All patients with diabetes mellitus should have regular fundus examination, even if their vision
is normal. Patients with retinopathy requiring laser treatment may still have normal vision.
NIDDM patients should be examined at diagnosis, and yearly thereafter. IDDM patients
should have an ophthalmological exam 5 yrs after diagnosis followed by an annual check-up.
Patients complaining of new visual symptoms should be seen sooner than these
recommended intervals.
Reflect!
How many diabetic patients do you look after? Do they all have regular ophthalmic
examination? Do you routinely check this when you see them?
Classification Features
Minimal Nonproductive
Diabetic
Retinopathy
(NPDR)
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Microaneurysms
only
Mild NPDR
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Microaneurysms +
haemorrhages
Hard exudates
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ModerateSevere NPDR
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As above + venous
beading
Proliferative
Diabetic
Retinopathy or
macular
oedema
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Fundus obscured
due to vitreous
haemorrhage
Retinal detachment
involving macula
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2.2 Treatment of diabetic retinopathy
Management of diabetic retinopathy involves control of the underlying diabetes, and
optimisation of blood pressure and cholesterol (if elevated). Laser treatment of diabetic
retinopathy is primarily to stabilise vision due to macular oedema, and to prevent
haemorrhage and tractional retinal detachment complicating proliferative retinopathy.
Caution!
Early diagnosis and referral of diabetic retinopathy is crucial to eventual success of
treatment.
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3. Sickle cell anaemia
Like diabetes mellitus, sickle cell anaemia can cause vitreous haemorrhage and retinal
detachment. Patients with the SC and S Thal form of the disease are more likely to have
ocular complications then the SS form. Ocular manifestations generally result from
intravascular sickling, haemolysis, haemostasis and resultant thrombosis leading to arteriolar
occlusion. This arteriolar occlusion causes restricted capillary perfusion and compensatory
neovascularization results.
Identification of preliminary signs such as thrombi and vascular occlusion are important for
early referral.
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4. Hypertension
Ocular manifestations of systemic hypertension are best understood if divided into two
classifications: those due to arteriolar sclerosis; and those due to elevated blood pressure.
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4.1 Arteriolar sclerosis
Systemic hypertension (with a diastolic pressure higher then 100mm Hg) accelerates the
normal process during aging of thickening and sclerosis of the arterioles. These changes in
the walls of the retinal arterioles can be readily observed during a routine fundus examination.
In a normal eye, ophthalmoscopic examination of the retina displays the retinal arterioles as
transparent tubes of blood with a streak of light reflected from the convex side of the vessel
(the central light reflex). As the retinal arterioles thicken due to the sclerosis, the light reflex
from these vessels also increases in width. As the arteriolar sclerosis advances and the light
reflex comes to occupy most of the with of the vessels; at this stage the vessels are called
copper-wire arterioles.
Changes in the arteriovenous crossing may also indicate systemic hypertension. The
arterioles and veins within the retinal tissue share a common sheath at crossing sites. Zones
of concealment (where the vein is hidden in the region it crosses underneath the artery) may
indicate hypertension. The vein may also be elevated or depressed by the arteriole and in
more severe cases may change direction up to 90 degrees as it reaches the arteriole.
Compression or constriction at the A/V crossing may result in dilation of the portion of the vein
distal to the crossing or other changes in vein integrity.
The changes in arteriovenous crossings listed above are most serious when located at or
beyond the second bifurcation of the arteriole (~1 disc diameter form the optic disc margin).
They can potentially lead to a decrease in visual acuity via occlusion of branch retinal veins.
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4.2 Elevated blood pressure
A moderate, acute increase in blood pressure causes a compensatory constriction of retinal
arterioles. If the rise in blood pressure is severe (diastolic pressure over 120mm Hg), fibrinoid
necrosis of the vessel wall may result with exudates, flame-shaped haemorrhages, cottonwool spots and occasionally whitish swelling and oedema of significant portions of the retina.
An optic disc resembling the swelling present in papilloedema may also be seen in the most
severe form of hypertensive retinopathy.
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4.3 Screening for hypertensive retinopathy
The thickening of vessel walls in arteriolar sclerosis guards against fibrinoid necrosis.
Because of this, changes due to acute hypertension are best seen in previously normal
arterioles. Differentiation between normal age related changes and chronic hypertensive
vascular changes are difficult. The best indicators of hypertension are, in order of importance;
changes in the retinal arterioles; focal narrowing; changes in arterioventricular crossing.
Caution!
If blood pressure must be lowered (eg due a severe acute increase in blood pressure), it
is imperative to do so in a controlled fashion to reduce risk of optic nerve infarction.
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5. Inflammatory conditions
A number of systemic inflammatory conditions may have clinical implications in the eye.
They include:
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ankylosing spondylitis
Reiter's syndrome
psoriatic arthritis
sarcoidosis
juvenile rheumatoid arthritis
all of which may cause uveitis and other ocular complications.
Juvenile rheumatoid arthritis is a childhood inflammatory disease with serious ocular
implications. Iritis is present in 10% of sufferers and if not recognised can lead to
complications such as glaucoma, cataract and corneal calcification.
Golden Rule!
Patients who have juvenile rheumatoid arthritis should have quarterly visits with the
ophthalmologist.
Other inflammatory conditions, such as rheumatoid arthritis and systemic lupus
erythematosus, may also appear in the eye. They primarily present as dry eye with symptoms
of grittiness and burning in the eye. Lubricating ointment or artificial tears is adequate
treatment in all but the most severe cases.
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6. Systemic infections
AIDS
AIDS has various manifestations in the eye. Amongst the most common are cotton-wool
spots (AIDS retinopathy), cytomegalovirus retinitis and Kaposi's sarcoma of the eyelids.
Cotton-wool spots are the sole ocular finding in approx 50% of AIDS patients. They occur due
to occlusions of retinal capillaries that result in accumulation of axoplasm in the retinal nerve
fibre layer. Occasionally, herpes zoster, herpes simplex, conjunctival microangiopathy, luetic
and toxoplasmic uveitis and CNS involvement causing visual field and oculomotor defects are
seen.
(Illustration: Kaposi's sarcoma of the eyelid. Photo courtesy of Alex Mackay)
Golden Rule!
Any patient diagnosed with HIV should be referred to an ophthalmologist for a complete
ophthalmological examination.
Other Systemic Infections and Infestations
All of the following may cause significant ocular complications:
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tuberculosis,
leprosy,
toxoplasmosis,
herpes zoster
herpes simplex
Herpes zoster and simplex are dealt with in detail elsewhere.
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7. Thyroid disease
Thyroid diseases, eg Graves' disease, are important autoimmune diseases that present
clinical features in the eye. A common characteristic of thyroid disease is exophthalmos
(protrusion of the globes), presenting with retraction of the upper and lower eyelid with upperlid lag on downgaze. The resulting appearance is commonly called the "Thyroid stare".
Upper and lower eyelid retraction and exophthalmos can cause the patient to complain of
irritation, foreign body sensation and tearing as a result of corneal exposure and drying.
These symptoms can be remedied with artificial tear preparations and lubricating eye
ointment at night.
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8. Myasthenia gravis
Myasthenia gravis is an autoimmune disease caused by an abnormality at the neuromuscular
junction. It is characterized by abnormal and excessive fatigability of skeletal muscles and
usually presents in women aged 20-40. Around 60% of patients suffering from myasthenia
gravis show ocular symptoms as their primary presentation so it is important not to overlook
the clinical features involved.
Clinical features:
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Bilateral but asymmetrical ptosis, worse towards the end of the day or when the
patient is tired
Test for the 'twitch sign of Crogan' by asking the patient to rapidly redirect his/her
gaze from the downward position to the primary position. A positive twitch test will be
indicated by the upper lid twitching upward and then slowly resettling to its ptotic
position.
Diplopia - extraocular muscle involvement appears to follow no set pattern by all
fields of gaze should be examined to check for diplopia.
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9. Cancer and the eye
Primary cancer in the eye is uncommon. Most ocular cancers arise secondarily. At autopsy,
approximately 5% of cancer patients have ocular or orbital metastases. Approximately 3% of
systemic lymphoma sufferers have proptosis or reduced eye motility. Leukaemic infiltration of
ocular tissues can occur in children and patients with leukaemia commonly develop
superficial retinal, pre-retinal or subconjunctival haemorrhages as a result of
thrombocytopenia.
Cancer treatments may have deleterious effects on the eye. Radiation of tumours close to the
eye may produce cataract, as the lens is sensitive to radiation in the 2000 rads range.
Some types of cancer chemotherapy may have ocular repercussions.
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Vincristine injections may cause optic neuropathy.
Superficial keratitis may develop from cytosine arabinoside
BCNU injection into the carotid may cause retinal artery occlusion.
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References
1. Hunyor, A.P., 2001, Age related macular degeneration and diabetic eye disease,
Chatswood Retinal Service.
2. Bradford, C.A.,1999, Basic ophthalmology for medical students and primary care
residents, 7th edn., American Academy of Ophthalmology, San Francisco, CA .