What is AV nicking and what does it indicate?

AV (arteriovenous) nicking occurs where retinal arterioles cross retinal veins. In hypertensive retinopathy, arteriolar walls thicken and the arteriole compresses the underlying vein at the crossing point, causing the vein to appear to narrow or disappear on each side of the arteriole. AV nicking is a sign of chronic hypertension and arteriolar sclerosis. It is associated with an increased risk of retinal vein occlusion at the crossing point.

What is a relative afferent pupillary defect (RAPD) and what causes it?

A RAPD (also called a Marcus Gunn pupil) is detected with the swinging flashlight test. When light is swung from the normal eye to the affected eye, the affected pupil paradoxically dilates (or dilates more) instead of constricting equally. This indicates a significant asymmetry in optic nerve function between the two eyes. RAPD is present in optic neuritis, optic neuropathy, large retinal lesions, and severe amblyopia. It is an objective sign of optic nerve disease.

Why do children with juvenile idiopathic arthritis need regular eye exams if their eye looks normal?

JIA can cause a chronic, non-granulomatous anterior uveitis that is typically asymptomatic and does not cause redness, pain, or photophobia, which is why it is called 'white-eye uveitis.' Despite looking externally normal, the eye can develop serious complications including posterior synechiae (iris adhesions), cataract, band keratopathy, and glaucoma from untreated intraocular inflammation. Regular slit lamp examinations, every 3 to 6 months depending on JIA subtype and ANA status, are essential to detect and treat uveitis before complications develop.

What is proptosis and what causes it in thyroid eye disease?

Proptosis (exophthalmos) is forward displacement of the globe from the orbit. It is measured with a Hertel exophthalmometer, and values above 20 mm (or asymmetry of more than 2 mm between eyes) are considered abnormal. In thyroid eye disease, the immune system targets orbital fibroblasts, causing them to produce excess glycosaminoglycans and expand the extraocular muscles and orbital fat. Because the orbital bony walls cannot expand, the increased orbital volume pushes the globe forward. Severe proptosis exposes the cornea, risking exposure keratopathy, and compresses the optic nerve at the orbital apex.

What is optic neuritis and how does it present?

Optic neuritis is inflammation of the optic nerve, most commonly associated with demyelinating disease (MS) but also occurring with infections, autoimmune diseases, and other causes. It typically presents with subacute unilateral vision loss over days, pain with eye movement, dyschromatopsia (reduced color saturation, especially red), and a RAPD on the swinging flashlight test. The optic disc may appear normal (retrobulbar optic neuritis, most common) or swollen (anterior optic neuritis, papillitis). Vision often recovers significantly within weeks to months, particularly after IV corticosteroid treatment, though deficits may persist.

Systemic Disease & the Eye for the CPO Exam

The eye is often called a "window to the body" because many systemic diseases leave characteristic signs in the ocular vasculature, nerves, and adnexa. Recognizing these ocular manifestations can help diagnose systemic conditions or monitor their progression. This is an important topic for the CPO exam and for clinical practice.

Hypertensive Retinopathy

Chronic or acute elevation of blood pressure damages retinal arterioles. The stages of hypertensive retinopathy progress from arteriolar narrowing to more serious complications:

Mild (Grade 1-2): Arteriolar narrowing and increased light reflex (silver or copper wire appearance), arteriovenous (AV) nicking where arterioles cross veins and compress them.
Moderate (Grade 3): Flame hemorrhages, cotton wool spots, and hard exudates.
Severe (Grade 4, Malignant Hypertension): All of the above plus papilledema (swelling of the optic disc). This indicates hypertensive emergency requiring immediate systemic treatment.

Papilledema (bilateral disc swelling from elevated intracranial pressure) is different from papillitis (unilateral disc inflammation from optic neuritis). Hypertensive papilledema occurs bilaterally. Any patient with disc swelling requires urgent evaluation.

Thyroid Eye Disease (Graves Orbitopathy)

Thyroid eye disease (TED), also called Graves orbitopathy, is an autoimmune condition usually associated with hyperthyroidism (Graves' disease). The immune system attacks orbital and periorbital tissue, causing inflammation and expansion of the extraocular muscles and orbital fat. Key features include:

Proptosis (exophthalmos): Forward displacement of the globe due to orbital tissue expansion.
Lid retraction: Upper lid appears elevated, revealing white sclera above the cornea (scleral show). The classic "staring" appearance.
Restrictive myopathy: Inferior rectus is most commonly affected, causing limitation of upward gaze and vertical diplopia.
Optic nerve compression: In severe cases, enlarged extraocular muscles compress the optic nerve at the orbital apex, causing optic neuropathy.

Multiple Sclerosis

Multiple sclerosis (MS) frequently manifests with ocular symptoms, sometimes as the presenting sign:

Optic neuritis: Inflammation of the optic nerve, causing sudden unilateral vision loss, pain with eye movement, and a relative afferent pupillary defect (RAPD). Often the first symptom of MS. Treated with IV corticosteroids.
Internuclear ophthalmoplegia (INO): A characteristic eye movement disorder caused by demyelination of the medial longitudinal fasciculus (MLF), causing impaired adduction on horizontal gaze with contralateral nystagmus. Bilateral INO in a young adult is highly suggestive of MS.

Rheumatologic Conditions

Many autoimmune and inflammatory conditions affect the eye:

Condition	Ocular Manifestation
Rheumatoid arthritis	Dry eye (keratoconjunctivitis sicca), scleritis, peripheral ulcerative keratitis
Ankylosing spondylitis	Acute anterior uveitis (recurrent, unilateral)
Juvenile idiopathic arthritis (JIA)	Chronic anterior uveitis, often asymptomatic (white-eye uveitis)
Sarcoidosis	Granulomatous uveitis, retinal vasculitis, optic nerve granulomas
Sjogren's syndrome	Severe dry eye, corneal staining

Sickle Cell Disease

Sickle cell retinopathy results from vaso-occlusion of retinal vessels by sickled erythrocytes. The most visually threatening complication is proliferative sickle cell retinopathy, characterized by sea-fan neovascularization in the peripheral retina that can cause vitreous hemorrhage and tractional retinal detachment. SC and S-thal genotypes carry higher risk of retinopathy than SS disease.

Key Takeaways

Hypertensive retinopathy progresses from arteriolar narrowing to AV nicking, hemorrhages, cotton wool spots, and papilledema in malignant hypertension.
Thyroid eye disease causes proptosis, lid retraction, restrictive myopathy (inferior rectus most common), and can cause compressive optic neuropathy.
MS commonly presents with optic neuritis and internuclear ophthalmoplegia; bilateral INO in a young adult is a red flag for MS.
Ankylosing spondylitis is the classic systemic cause of recurrent acute anterior uveitis; JIA causes a silent chronic uveitis requiring regular screening.
Recognizing ocular signs of systemic disease allows CPOs to alert the physician and facilitate appropriate systemic workup.