Fish-Eye Disease - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Fish-eye disease, also known as partial LCAT deficiency, is a condition where the clear front part of the eyes, called the corneas, gradually becomes cloudy. This cloudiness, which typically starts to show up during teenage years or early adulthood, appears as small grayish dots made of cholesterol spread across the corneas. Cholesterol is a fatty substance produced by the body and found in animal-derived foods. While it serves various important bodily functions, excessive amounts can be harmful. As fish-eye disease advances, the cloudiness in the corneas worsens, potentially resulting in significantly impaired vision.

What Is the Cause of Fish-Eye Disease?

Fish-eye disease stems from changes in the LCAT gene, which directs the creation of an enzyme called lecithin-cholesterol acyltransferase (LCAT). This enzyme is crucial in eliminating cholesterol from the bloodstream and tissues by facilitating its attachment to lipoproteins. Lipoproteins act as carriers, transporting cholesterol to the liver, which can be redistributed or expelled from the body. The LCAT enzyme operates through two main pathways: alpha- and beta-LCAT activity. The alpha-LCAT activity aids in bonding cholesterol to high-density lipoprotein (HDL), while the beta-LCAT activity is involved in linking cholesterol to other lipoproteins like very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL).

Mutations in the LCAT gene associated with fish-eye disease hinder the alpha-LCAT activity, diminishing the enzyme's capability to attach cholesterol to HDL. This disruption in the cholesterol elimination process results in cholesterol deposits in the corneas, causing opacity. It remains unclear why these deposits specifically affect the corneas in this condition. Mutations impacting alpha- and beta-LCAT activities lead to a condition known as complete LCAT deficiency, characterized by corneal opacities and additional symptoms affecting other parts of the body.

What Are the Symptoms of Fish Eye Disease?

Symptoms of this disease can vary from person to person, so that the experience may differ from others. It is important to consult the healthcare team for personalized information.

The following are some symptoms associated with this condition, along with their descriptions and how often they occur:

• Corneal Opacity: A decrease in the clarity of the cornea.

1. Synonyms: Corneal clouding, corneal opacities, scarring, or cornea clouding.

2. Frequency: Uncommon, very frequent, always.

• Angina Pectoris: Intermittent chest pain during physical activity or stress is linked to reduced blood flow to the heart muscle.

1. Frequency: Uncommon, occasional, always.

• Atherosclerosis: Buildup of plaque in medium and large arteries, leading to narrowing or blockage of blood flow.

1. Synonyms: Atherosclerotic cardiovascular disease, narrowing and hardening of arteries.

2. Frequency: Uncommon, occasional, always.

• Hepatomegaly: Abnormal enlargement of the liver.

1. Synonyms: Enlarged liver.

2. Frequency: Uncommon.

Is It Possible for This Disease to Be Inherited From Parents to Their Children?

This disease can be passed from parent to child through genetic mutations. This process is called inheritance. Understanding if other family members have had this disease, known as family health history, is crucial information for the medical team.

Different diseases have different inheritance patterns depending on the genes involved. This disease follows an autosomal recessive pattern.

Autosomal means the gene is located on one of the numbered chromosomes. In contrast, recessive means a child needs to inherit two copies of the mutated gene, one from an individual parent, to be affected. A carrier has only one copy of the genetic mutation and typically doesn't show symptoms.

If both biological parents carry the gene mutation, there is a 25 percent likelihood that their child will inherit two copies of the mutated gene, resulting in the disease. Additionally, there is a 50 percent chance that the child will inherit only one copy of the mutated gene, making them a carrier.

How to Diagnose Fish-Eye Disease?

Diagnosing fish-eye disease entails a thorough clinical assessment and specific laboratory and genetic tests. The ophthalmologic examination may reveal corneal opacities and ocular abnormalities, while blood tests measure lipid levels and LCAT enzyme activity. Genetic testing confirms mutations in the LCAT gene. Differential diagnosis is crucial to distinguish fish-eye disease from similar conditions. Family history assessment aids in understanding inheritance patterns. Imaging studies may supplement diagnosis by assessing lipid deposition. Early and accurate diagnosis enables timely intervention and management strategies tailored to mitigate ocular and cardiovascular complications associated with this rare genetic disorder.

What Is the Management of Fish-Eye Disease?

Currently, there is no cure for fish-eye disease, and the treatment aims to manage symptoms and reduce the risk of complications. Management strategies may include:

• Dietary Modifications: To help control lipid levels in the bloodstream, individuals with fish-eye disease must adopt a low-cholesterol and low-fat diet. This involves limiting the intake of foods high in cholesterol and saturated fats, such as red meat, full-fat dairy products, and processed foods. Emphasizing a diet rich in fruits, vegetables, whole grains, and lean proteins can support overall cardiovascular health and help reduce the risk of complications associated with elevated lipid levels.

• Medications: Pharmacological interventions may be necessary to manage dyslipidemia and reduce the risk of cardiovascular disease in individuals with fish-eye disease.

• Statins: These medications inhibit the production of cholesterol in the liver and are commonly prescribed to lower LDL cholesterol levels.

• Fibrates: Fibrates help reduce triglyceride levels and increase HDL cholesterol levels, which can benefit individuals with dyslipidemia. Other lipid-lowering agents, such as bile acid sequestrants and cholesterol absorption inhibitors, may also be considered based on patient characteristics and lipid profiles.

• Eye Care: Regular ophthalmologic examinations are essential for monitoring the progression of corneal opacities and other ocular complications associated with Fish-Eye Disease. Treatment options for corneal opacities may include lubricating eye drops to alleviate dryness and discomfort. Surgical interventions such as corneal transplantation may improve visual function in severe cases.

• Lifestyle Modifications: Encouraging lifestyle changes can help improve overall health and lessen the risk of cardiovascular complications in individuals with Fish Eye Disease.

• Regular Exercise: Physical activity can help maintain a healthy weight, improve lipid metabolism, and reduce the risk of cardiovascular disease.

• Smoking Cessation: Quitting smoking is crucial for individuals with Fish-Eye Disease, as smoking can exacerbate lipid abnormalities and increase the risk of cardiovascular complications.

• Stress Management: Adopting stress-reducing techniques such as mindfulness meditation, yoga, or relaxation exercises can promote emotional well-being and cardiovascular health.

• Genetic Counseling: Genetic counseling plays a crucial role in helping individuals with Fish-Eye Disease, and their families understand the genetic pattern of the condition and make informed decisions about family planning. Genetic counselors provide support, education, and resources to individuals and families affected by genetic disorders, helping them navigate the complexities of genetic testing, inheritance, and risk assessment.

Conclusion

Fish-eye disease is a rare genetic disorder that affects lipid metabolism and can lead to various eye and cardiovascular complications. While there is currently no cure for the condition, early diagnosis and appropriate management can help individuals lead fulfilling lives and reduce the risk of complications. Further research into the underlying mechanisms of fish-eye disease is needed to develop more effective treatment strategies and improve outcomes for affected individuals.