Fundus Albipunctatus - An Overview

Introduction

Fundus albipunctatus is a rare genetic eye condition where small, round, yellowish-white spots appear throughout the retina, except for the central area called the fovea. This condition usually shows up in childhood and causes night blindness that does not get worse over time. People with this condition take longer than usual to adjust their eyes to changes in light, both in bright and dark conditions. Sometimes, the central part of the vision, known as the macula, can also be affected, leading to a decrease in the sharpness of vision as they age.

What Is Fundus Albipunctatus?

Fundus albipunctatus is a condition where people have trouble seeing in low light, known as night blindness, and there are white or yellowish spots in the retina, which is the part of the eye that senses light. These spots can be seen when a person gets their eyes checked.

People with fundus albipunctatus encounter night blindness from a young age. Specifically, they face difficulty adjusting to dark environments after being in bright light, like driving into a tunnel on a sunny day. This adjustment can take several hours. Their vision under bright lighting conditions is typically unaffected.

The white or yellowish spots are particularly concentrated towards the retina's outer edge or periphery. The number of these spots varies among those affected; some may have overlapping spots, while others have fewer. Interestingly, in certain individuals, these spots tend to decrease in size or fade as they age, although their night vision remains unchanged.

Although fundus albipunctatus usually remains stable, some individuals may experience additional eye complications. These may include deterioration of the central part of the retina, called the macula, resulting in macular degeneration and loss of cone cells, which can impact vision in well-lit environments.

What Is the Cause of Fundus Albipunctatus?

Fundus albipunctatus mainly occurs because of changes in a gene called RDH5. This gene helps in the visual cycle, where light gets turned into signals the brain interprets as sight. Other gene changes can sometimes also cause this condition, but it is rare.

A molecule called 11-cis retinal needs to be reused in the visual cycle. This type of vitamin A molecule is crucial for turning light into signals. The RDH5 gene makes an 11-cis retinol dehydrogenase 5 enzyme, which helps with one part of this recycling. It changes a molecule called 11-cis retinol into 11-cis retinal.

This enzyme might not work well when there are changes in the RDH5 gene. This means there is not enough 11-cis retinal around. Without enough, the signals needed for vision do not happen properly, and sight is affected, especially in low light. In dim light, our eyes rely greatly on the 11-cis retinol dehydrogenase 5 enzyme to make 11-cis retinal. So, if there is not enough of this enzyme, it is harder to see in the dark. Scientists think that when the enzyme does not work right, other molecules like 11-cis retinol build up, leading to spots in the fundus albipunctatus.

How to Diagnose Fundus Albipunctatus?

Diagnosing fundus albipunctatus typically involves a thorough eye examination conducted by an ophthalmologist or a retina specialist. The diagnostic process may include the following steps:

• Medical History and Symptoms Assessment: The healthcare provider will begin by gathering information about the patient's medical history, including any family history of vision problems or retinal disorders. They will also inquire about symptoms such as night blindness or difficulties seeing in low-light conditions.

• Visual Acuity Testing: Using an eye chart, this standard eye test measures how well the patient can see at various distances. While fundus albipunctatus primarily affects night vision, assessing visual acuity helps determine if there are any additional vision impairments, especially those affecting central vision.

• Ophthalmoscopy: During this examination, the doctor uses a specialized instrument called an ophthalmoscope to examine the inside of the eye, including the retina. The characteristic yellowish-white lesions scattered across the retina are indicative of fundus albipunctatus. The macula, which may or may not be affected, is also evaluated for any signs of involvement.

• Electroretinography (ERG): Electroretinography is a diagnostic procedure used to assess the retina's electrical reactions when exposed to light stimuli. For individuals affected by fundus albipunctatus, Electroretinography (ERG) might detect irregularities in the retina's electrical signals, especially when exposed to dim light stimuli. This test helps confirm the diagnosis and assess the severity of retinal dysfunction.

• Genetic Testing: Genetic testing may be recommended to identify specific gene mutations associated with fundus albipunctatus, particularly the RDH5 gene. Molecular genetic analysis can provide definitive confirmation of the diagnosis and help determine the inheritance pattern of the condition, which can be valuable for genetic counseling and family planning.

What Is the Treatment of Fundus Albipunctatus?

Treatment for fundus albipunctatus primarily focuses on managing symptoms and optimizing visual function, as there is currently no cure for the condition. While full restoration of receptor cell function is not possible, certain interventions may help alleviate symptoms and improve the quality of life for affected individuals:

• High Oral Doses of Beta-Carotene: Beta-carotene, a precursor of vitamin A, has been suggested as a potential treatment option for fundus albipunctatus. Studies have shown that high oral doses of beta-carotene may improve night blindness, a common symptom of the condition. Beta-carotene supplementation aims to replenish retinal stores of vitamin A, which are crucial for the visual cycle. However, the efficacy of this treatment approach may vary among individuals, and it is important to discuss it with a healthcare professional before supplementation.

• Low Vision Aids: For individuals with fundus albipunctatus who experience central visual impairment, low vision aids can optimize remaining vision and enhance functional abilities. These aids may include magnifying glasses, telescopic lenses, specialized filters to reduce glare, and other visual assistive devices. Low-vision rehabilitation programs can provide comprehensive assessments and customized strategies to maximize visual performance and independence in daily activities.

• Genetic Counseling: Genetic counseling is essential to managing fundus albipunctatus, particularly for individuals and families affected by the condition. Genetic counselors can offer information and support regarding the disorder's genetic basis, inheritance patterns, and potential implications for family members. They can also facilitate genetic testing, guide family planning options, and connect families with resources and support networks within the genetic and rare disease community.

Conclusion:

Fundus albipunctatus poses significant challenges for affected individuals, impacting their ability to navigate low-light environments and potentially leading to central visual impairment over time. Through continued research efforts and advancements in genetic and therapeutic modalities, there is hope for improved diagnosis, management, and treatment of this rare retinal disorder, ultimately enhancing the quality of life for those living with fundus albipunctatus.