Senilis

Alan R. Forman


BASICS


DESCRIPTION


• Arcus senilis is a yellowish-white ring of extracellular lipid deposition in the peripheral cornea separated from the limbus by a narrow (<1 mm) clear zone. It is seen most frequently in the elderly, but can present in children and rarely at birth. In younger patients, there is an association with hyperlipidemia and cardiovascular disease risk factors. It does not interfere with vision and requires no treatment.


• Synonyms: Corneal arcus, gerontoxon


– In children: Arcus juvenilis, anterior embryotoxon


EPIDEMIOLOGY


Prevalence


• Increases with age (13)


• Higher in black population (1,3)


• Higher in men (3)


• Estimates of prevalence vary


• Approximately 65% of those 50 years or older (4)


RISK FACTORS


• Older age


• Hypercholesterolemia


Genetics


• Early onset arcus (by age 45) is common in familial hyperlipoproteinemias.


– Familial hypercholesterolemia is an autosomal dominant inherited defect in lipoprotein metabolism.


Homozygotes often present with arcus earlier than heterozygotes (5).


PATHOPHYSIOLOGY


Cholesterol, cholesterol esters, triglycerides, and phospholipids deposit within the cornea causing no functional limitations


ETIOLOGY


• Product of aging and unlikely to represent disturbed metabolism in elderly patients


• In familial hyperlipoproteinemias, development of premature arcus relates to age of patient.


– In these cases, it is the duration of the dyslipidemic disease, not its severity, that is associated with formation of arcus (6).


COMMONLY ASSOCIATED CONDITIONS


• Most closely associated with aging


• Associated with hyperlipidemia and cardiovascular disease:


– Early onset arcus (childhood and early adulthood) is seen with familial hypercholesterolemia, and with type III, IV, and V hyperlipoproteinemia.


– Corneal arcus before the age of 45 is included in the criteria for diagnosing familial hypercholesterolemia (5).


– Reported as a prognostic factor for cardiovascular disease mortality in hyperlipidemic men aged 30–49 years (1)


– Also reported as a prognostic factor for coronary artery disease in men aged 30–49 years independent of its association with hyperlipidemia (1)


• When present in children it is called arcus juvenilis:


– Associated with certain congenital ocular anomalies, such as blue sclera, megalocornea, and aniridia


– Also associated with familial hyperlipoproteinemias, as stated above


DIAGNOSIS


HISTORY


• Gradual formation of a bilateral white corneal ring. Some patients complain of “changing eye color.”


– For example, a patient with a dark brown iris may state that his or her peripheral iris is becoming lighter.


• Arcus does not cause any visual disturbances.


PHYSICAL EXAM


• A yellowish-white ring is visible in the peripheral cornea with a narrow clear zone separating it from the limbus.


– While examination is aided by the use of a slit lamp, arcus can be detected by examination with the naked eye and the use of a light source.


• On slit lamp examination, the distribution of lipid deposit is better appreciated.


– Deposits are most concentrated in the area of Descemet’s membrane (a deep corneal layer) and Bowman’s membrane (a superficial corneal layer).


– Appears as two wedge-shaped opacities:


One wedge with the base on the superficial membrane and the apex pointing posteriorly into the corneal stroma


The other wedge with the base on the deep membrane and the apex pointing anteriorly into the corneal stroma


• Peripheral margin of the arcus forms a sharply defined edge, whereas the central margin is less distinct.


DIAGNOSTIC TESTS & INTERPRETATION


Lab


Patients younger than 50 years require serum lipid measurements (1)[A].


Imaging


In patients less than 50 years of age, consider echocardiogram/stress echocardiogram in the context of other findings.


Diagnostic Procedures/Other


• Any patient younger than 50 years requires detailed work-up for cardiovascular risk factors (1)[A].


– Assess for history of hypertension, diabetes, family history, symptoms of angina, exercise, and smoking


– EKG, stress test


• Children must be investigated for dysfunction of lipoprotein metabolism.


Pathological Findings


• Grossly, a white ring of lipid deposit limited to the peripheral cornea with a 0.3–1 mm clear zone separating it from the limbus:


– Ring begins as two arcs, one near the superior corneal margin and one near the inferior margin. Arcs grow until they meet circumferentially completing a 360° ring.


• Histologically, two concentric rings form within the cornea and extend toward one another in the anterior–posterior plane.


– Extracellular lipid deposits initially appear in Descemet’s membrane forming a triangular shape with the base along Descemet’s membrane and the apex extending into the corneal stroma.


– Lipid deposits also form an anterior triangular shape with the base along Bowman’s membrane and the apex extending into the stroma.


– As more lipid is deposited, the apices of the triangles extend toward one another and eventually fuse forming one ring.


• Deposits consist of cholesterol, cholesterol esters, phospholipids, and triglycerides (2,3).


• Similar lipid deposits also form within the sclera, but cannot be seen clinically because of the normal white scleral color.


DIFFERENTIAL DIAGNOSIS


• Kayser–Fleischer ring: Red, brown, or green ring of abnormal corneal copper deposition forming on Descemet’s membrane (deep corneal layer) in Wilson’s disease


• Chalcosis: Copper deposition in the cornea from an intra-ocular foreign body


• Band keratopathy: Calcium deposition in the superficial corneal layer; may cause decreased vision and foreign body sensation


• Limbal girdle of Vogt: White semicircular arc causing peripheral opacity in the nasal region of the cornea bilaterally


• Terrien’s marginal degeneration: Bilateral thinning of the peripheral corneal stroma forming a 1–2 mm gutter


• Idiopathic furrow degeneration: Thinning of the peripheral cornea; usually requires no treatment


• Staphylococcal marginal keratitis: Infectious corneal infiltrate, often with overlying epithelial defect


• Lecithin-cholesterol acetyltransferase (LCAT) deficiency: Corneal opacity resembling arcus senilis in patients with LCAT gene mutation, associated with anemia, proteinuria, and premature atherosclerosis


TREATMENT


ADDITIONAL TREATMENT


General Measures


No treatment required


ONGOING CARE


FOLLOW-UP RECOMMENDATIONS


• No follow-up is required for patients older than 50 years.


• Patients younger than 50 years must follow up with a cardiovascular risk factor evaluation with a primary care provider.


PATIENT EDUCATION


• Older patients should be reassured that corneal arcus is a common finding with aging. There are no complications, no treatment is required and it will not interfere with vision.


• Younger patients with arcus should be educated that it may indicate hyperlipidemia and an evaluation is recommended.



REFERENCES


1. Chambless LE, Fuchs FD, Linn S, et al. The association of corneal arcus with coronary heart disease and cardiovascular disease mortality in the Lipid Research Clinics Mortality Follow-up Study. Am J Public Health 1990;80:1200–1204.


2. Cogan D, Kuwabawa T. Arcus senilis: It’s pathology and histochemistry. Arch Ophth 1959;61:353.


3. Barchiesi B, Eckel R, Ellis P. The cornea and disorders of lipid metabolism. Surv Ophthal 1991;36(1):1–22.


4. Chua BE, Mitchell P, Wang JJ, et al. Corneal arcus and hyperlipidemia: Findings from an older population. Am J Ophthalmol 2004;137:363–365.


5. Civeira F. Guidelines for the diagnosis and management of heterozygous familial hypercholes- terolemia. Atherosclerosis 2004;173:55–68.


6. Winder AF. Relationship between corneal arcus and hyperlipidaemia is clarified by studies in familial hypercholesterolaemia. Br J Ophthalmol 1983;67:789–794.

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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Senilis
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