Eye health

Scleral icterus-Causes, Diagnosis and Treatment

Scleral icterus is a part of Jaundice which we might have heard very commonly. Scleral icterus is the colored pigmentation of the white part of the eye or the sclera. Due to scleral icterus, our eye appears very yellow. In some people, the eyes may also appear greenish or orangish due to sclera icterus.

Scleral icterus is only a symptom of other diseases. For example, it can be a symptom of liver disorders, and it can also occur due to many other disorders which we shall discuss in this article. If the disease-causing scleral icterus is treated, sclera icterus also disappears on its own.

Types of Scleral icterus, Causes of scleral icterus and the mechanism of developing scleral icterus:

scleral icterus
Image source: mmgazette.com

There are 3 main types of scleral icterus based on the pathophysiology involved in developing the disease. They are:

  1. Prehepatic scleral icterus
  2. Intrahepatic scleral icterus
  3. Posthepatic scleral icterus

All these types of scleral icterus are divided based on the liver, and the pathophysiology or mechanism of developing the disease in relation to the liver. Let us first try to understand the pigment called bilirubin.

Bilirubin is a byproduct of hemoglobin metabolism. We all know that hemoglobin is a part of the red blood cells. When the red blood cells become old and break down, the hemoglobin is metabolized and develops into bilirubin. This form of bilirubin produced by breaking down of RBC’s id called unconjugated bilirubin.

This unconjugated bilirubin goes to the liver, where the liver converts the unconjugated bilirubin to a product called conjugated bilirubin. Unconjugated bilirubin is water-insoluble, and it is carried by albumin in the blood. Conjugated bilirubin is water soluble, and it is secreted by the liver into the bile. This bile is released into the intestines to help with the digestion of the food.

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Then the bile is reabsorbed into the blood and then it also reaches the kidneys and is excreted through the urine and also through the stool or feces. Bile pigments make our urine and stool look yellowish.

If there is any impairment in this mechanism of normal bilirubin and bile metabolism due to any disease, bilirubin pigment gets accumulated in the blood. Then this pigment gets deposited in the sclera and conjunctiva of the eyes, leading to their yellowishness. This is called scleral icterus. This excess bilirubin in the blood also gets deposited in the skin, leading to yellowishness and itching of the skin. The sclera icterus and yellowishness of the skin together are called Jaundice, which is very popularly known amongst the people.

Prehepatic scleral icterus or jaundice:

In this condition, the RBC’s break down more frequently than normal leading to the accumulation of unconjugated bilirubin in the blood, leading to scleral icterus and jaundice. There are many conditions which cause prehepatic scleral icterus. Some of them are:

  1. Malaria: Disease caused by a parasite called plasmodium (with species like vivax, ovale, malariae, and falciparum), and transmitted by mosquitoes.
  2. Thalassemia: Disease in which RBC shape is abnormal due to which it breaks down prematurely. It is a genetic disorder which is more common in people of certain races like African, Middle Eastern and Mediterranean people.
  3. Sickle cell anemia: It is also a disease which is similar to Sickle cell anemia as it has abnormal shaped Red blood cells which break down prematurely. It is also more common in Black Africans, etc.
  4. Hereditary Spherocytosis: In this condition, the red blood cells have a round shape instead of the normal shape of the RBC’s. Due to this, they break down when passing through narrow blood vessels and capillaries. This condition also leads to scleral icterus. It is also a genetically acquired condition.
  5. Criggler Najar syndrome: In this syndrome, the enzyme which facilitates the transport of the bilirubin from the blood into the liver is absent in the person leading to increasing of unconjugated bilirubin in the blood and then to scleral icterus. It is also a genetically acquired disorder.
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Intrahepatic scleral icterus or jaundice:

In this type of scleral icterus, there is some sort of abnormality within the liver to convert unconjugated bilirubin to the conjugated form. Some of the causes of this type of scleral icterus are:

  • Viral hepatitis: It is caused by various types of viruses. All types of viral hepatitis cause scleral icterus. The types of viral hepatitis are Hepatitis A, B, C, D and E. Hepatitis A and E are transmitted through feco-oral route, that is through contaminated food and water. Hepatitis B, C, and D are transmitted through sexual transmission, using contaminated IV needles, IV drug abuse, transmission from infected mother to fetus, getting a blood transfusion with contaminated blood.
  • Infectious mononucleosis: It is also known as glandular fever. It is caused by a virus called Ebstein Barr virus or EBV. It also causes scleral icterus.
  • Alcoholic liver disorders: Excess alcohol consumption on a long-term basis can damage the liver
  • Drugs: Excess consumption or overdose of certain drugs like Paracetamol can also damage the liver
  • Gilbert syndrome
  • Autoimmune hepatitis
  • Primary biliary cirrhosis
  • Dubin Johnson syndrome
  • Harmful chemicals exposure
  • Primary sclerosing cholangitis
  • Liver carcinoma or liver cancer or hepatocellular cancer

Posthepatic scleral icterus or jaundice:

The bilirubin is secreted from the liver into the duodenum through the common bile duct. Common bile duct ultimately joins the pancreatic duct to form hepatopancreatic duct and releases bile into the liver. If there is any obstruction in the pathway of the release of bilirubin, it is called posthepatic scleral icterus or jaundice.

This leads to increased levels of conjugated bilirubin in the blood. The conditions causing this type of scleral icterus also cause other symptoms like fatty white stools or steatorrhea, dark-colored or yellow colored urine, weight loss, etc in addition to icteric sclera or jaundice. The most common condition leading to posthepatic icterus of sclera are:

  • Cholelithiasis or Gallstones
  • Pancreatitis: It can be due to acute pancreatitis lasting for few days or chronic pancreatitis lasting over years
  • Pancreatic cancer
  • Gallbladder cancer

Most common causes of scleral icterus:

Although we have discussed many causes of jaundice, only a few of them are common. Many of these conditions occur rarely in some people. So, the most common causes of icterus of sclera are:

  • Viral hepatitis (Hepatitis A, B, C, D, E)
  • Alcoholic hepatitis
  • Cholelithiasis or Gallstones
  • Infectious mononucleosis
  • Gallbladder disorders
  • Biliary colic
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30 plus causes scleral icterus or jaundice:

  • Liver damage or injury
  • Esophageal varices
  • Leptospirosis
  • Budd Chiari syndrome
  • Cirrhosis
  • Boutonneuse fever
  • Erythroblastosis fetalis
  • Galactosemia
  • G6PD deficiency
  • Porphyria cutanea tarda
  • Dubin Johnson syndrome
  • Gilbert syndrome
  • Rotor syndrome
  • Criggler Najar syndrome
  • Malaria
  • Primary biliary cirrhosis
  • Primary sclerosing cholangitis
  • Hereditary spherocytosis
  • Thalassemia
  • Sickle cell anemia
  • Yellow fever
  • Toxoplasmosis
  • Scurvy
  • TTP or Thrombotic Thrombocytopenic purpura
  • Wilson disease
  • Histoplasmosis
  • Hepatocellular carcinoma
  • Pancreatic carcinoma
  • Hemochromatosis
  • Echinococcus granulosus or Hydatid disease
  • Cholangiocarcinoma
  • Hepatic abscess
  • Amebiasis affecting the liver

Diagnosis of scleral icterus or jaundice:

In order to treat the underlying cause of icteric sclera, the doctors need to perform several tests to identify the disorder causing scleral icterus. The first step is to perform liver function tests, which include the levels of total bilirubin, conjugated bilirubin, unconjugated bilirubin, levels of enzymes like AST, ALT. GGT, ALP, etc in the blood.

This helps the physicians to arrive at a diagnosis of the underlying cause of icteric sclera to some extent. If necessary another test might also be done like urine exam to detect bile pigments in urine, USG abdomen, etc.

Treatment of scleral icterus or jaundice:

The treatment of icteric sclera depends on the cause of scleral icterus. If the patient is having the G6PD deficiency, he will have to avoid taking drugs which trigger hemolysis or break down of RBC’s. So, you need to mention to your doctor about G6PD deficiency whenever you go for any treatment.

If you are having viral hepatitis, you might be given antiviral drugs or managed conservatively based on the type of viral hepatitis you have. If you have liver failure, you will need a liver transplant. In newborns with scleral icterus or jaundice, called neonatal jaundice, either phototherapy or exchange transfusion is done based on the levels of bilirubin in them and whether they are preterm or term baby, etc.

Whatever the cause of scleral icterus is, it will be resolved if the underlying cause of the problem is resolved.

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