Scleral Jaundice: Color Characteristics
Scleral jaundice appears as a yellow discoloration of the sclera (the white part of the eye), which becomes clinically visible when serum bilirubin levels exceed 2.5 to 3 mg/dL. 1
Clinical Appearance and Detection
The sclera transitions from its normal white color to yellow when bilirubin accumulates in tissues, with this yellowing being one of the earliest and most reliable physical signs of hyperbilirubinemia 1
Clinical jaundice manifests as yellowing of both the eyes (sclera) and skin, though scleral icterus typically becomes apparent before skin changes due to the high elastin content in scleral tissue, which has particular affinity for bilirubin 1
The yellow coloration ranges from pale yellow in mild cases to deep yellow or even greenish-yellow in severe or prolonged cholestasis 2
Spectrum of Yellow Discoloration
In early or mild jaundice (bilirubin 2.5-5 mg/dL), the sclera shows a subtle pale yellow tint that may be most visible in natural daylight 1
In moderate jaundice (bilirubin 5-15 mg/dL), the yellow color becomes more pronounced and easily recognizable on routine examination 1
In severe jaundice (bilirubin >15 mg/dL), the sclera may appear deep yellow to orange-yellow, and in cases of prolonged cholestasis, a greenish tinge may develop due to biliverdin accumulation 2
Special Considerations in Cholestatic Disease
In cholestatic conditions like primary sclerosing cholangitis (PSC) or primary biliary cholangitis (PBC), the scleral yellow color may be accompanied by other signs of chronic liver disease, though total bilirubin levels are typically normal at initial diagnosis in the majority of PSC patients 2
An elevated serum bilirubin in PSC patients is a marker of poor prognosis and indicates more advanced disease 2
In drug-induced cholestatic liver injury, the scleral jaundice develops with predominantly direct (conjugated) hyperbilirubinemia, usually greater than 35% of total bilirubin 2
Bronze Discoloration: A Rare Variant
In infants with cholestatic jaundice who receive phototherapy, a rare complication called "bronze infant syndrome" can occur, where the skin, serum, and urine develop a dark, grayish-brown discoloration rather than typical yellow 2
This bronze discoloration is thought to result from accumulation of porphyrins and other metabolites in patients with cholestasis, though the pathogenesis remains incompletely understood 2
Diagnostic Implications
The presence of scleral icterus indicates that bilirubin is being produced and circulating, but the specific yellow hue does not reliably distinguish between hepatocellular versus obstructive causes of jaundice 1
Scleral imaging using smartphone technology has demonstrated that scleral chromaticity correlates with total serum bilirubin levels (r = 0.75), with sensitivity of 100% for detecting TSB >250 μmol/L when using ambient-subtracted sclera color analysis 3
The conjunctival absorption spectrum shows distinct peaks at 460 nm and 600 nm that correlate with bilirubin concentration, providing objective measurement of the yellow pigmentation 4
Clinical Pitfalls
Do not rely solely on visual assessment of scleral color to quantify jaundice severity—always obtain serum bilirubin levels, as clinical detection is subjective and influenced by ambient lighting conditions 1, 3
In patients with Gilbert's syndrome, intermittent mild scleral icterus may occur with unconjugated hyperbilirubinemia (typically <4-5 mg/dL) during periods of stress, fasting, or illness, but this does not indicate liver disease 2
Scleral yellowing must be distinguished from other causes of scleral discoloration, including pinguecula (yellowish deposits on the conjunctiva unrelated to bilirubin) and carotenemia (which causes yellow skin but spares the sclera) 1