Overview

Fucosidosis is a rare genetic condition caused by genetic changes in the FUCA1 gene. The severity of Fucosidosis features can vary widely. Individuals with Fucosidosis often present with a decline in brain function, skin abnormalities, skeletal issues, growth challenges, and changes in facial features.¹ Fucosidosis is categorised into 2 types. Type 1 usually presents in early infancy and is associated with quick progress of features and high mortality.

On the other hand, type 2 begins before age 2 and advances at a slower pace.³ This article will provide a comprehensive overview of ocular abnormalities associated with Fucosidosis, along with their diagnosis methodology and management strategies.

Common ocular abnormalities in Fucosidosis

Approximately 120 cases have been reported globally, with a small portion of cases documenting ocular abnormalities.⁹ The following section will detail abnormalities found with eye development, the eye's anterior (front) segment, and the eye's posterior (back) segment.

Abnormalities of the anterior segment

1. Corneal abnormalities 

The cornea is the clear, curved surface covering your eye's front. In Fucosidosis individuals can present with clouding of the cornea and 11% of individuals can have corneal opacities.^5,7 Corneal opacification is when the cornea does not allow any light to enter and can leave an individual with blurred vision.

2. Abnormalities of conjunctival vessels 

The conjunctiva is a thin, clear layer that protects your eye. The conjunctiva lines the inside of the eyelid and covers the white part of the eye (sclera). Approximately 53% of individuals with Fucosidosis can present with dilated (enlarged) and tortuous (twisted) conjunctival vessels, and 41% of individuals showed conjunctival vessel microaneurysms.^2,5 

3. Blepharospasm 

Blepharospasm is where the muscles around your eyes twitch or spasm rapidly and uncomfortably.⁶ In some severe cases blepharospasm can cause your eyes to close involuntarily. 

Abnormalities of the posterior segment 

1. Tortuous retinal vessels 

The retina is a light-sensitive layer at the back of the eye that captures visual signals from the optic nerve and turns them into images for an individual to see. 54% of individuals with Fucosidosis present with dilated and tortuous retinal veins.⁵ 

2. Pigmentary retinopathy

Pigmentary retinopathy is an eye condition where the retina develops abnormal deposits of pigment. This can lead to a gradual loss of vision, often starting with difficulty seeing in low light. 7% of individuals with Fucosidosis present with pigmentary retinopathy.⁵

Diagnosis of ocular abnormalities in Fucosidosis

The following sections will give an overview of how ocular abnormalities can be investigated.

Examining the anterior segment of the eye

A slit-lamp, which acts as a microscope with a light can be used to examine the front part of the eye, which includes; the eyelids, cornea, iris, and lens.² 

Examining the posterior segment of the eye 

A slit lamp can also be used to examine the back of the eye which includes the retina and the optic nerve. For a more in-depth examination, a clinician may put dilating drops in an individual's eyes to dilate (widen) the pupil to provide a better view of the optic nerve and the retina for examination.

An OCT (Optical coherence tomography) can also be used to take pictures at the back of the eye to help visualise the retina and optic nerve. 

Management and treatment of ocular abnormalities 

While there is no cure for Fucosidosis, treatment aims to manage the various ocular abnormalities and symptoms associated with the condition. The following section will detail ocular treatment options. 

Correcting refractive error

A refractive error examination can assess whether someone needs glasses or contact lenses, which is crucial for visual development, especially in children. If vision in one or both eyes is affected, it may lead to amblyopia (reduced vision). 

Visual aids 

Devices like magnifying glasses, specialised lenses, and electronic aids can help individuals utilise their vision better.⁸

Supplements 

Some forms of pigmentary retinopathy, like retinitis pigmentosa, may benefit from supplementary vitamin A, which can slow the progression of vision loss.⁸ 

Surgery 

Corneal transplant 

A corneal transplant is a surgical procedure where an opacified or cloudy cornea is replaced with a healthy cornea from a donor.⁴ This can help improve vision, relieve pain, and fix any damage to the cornea.

Counselling

There is no cure for pigmentary retinopathy, but for families affected by Fucosidosis, genetic counselling is recommended to understand the inheritance patterns and risks for future pregnancies.²

Impact of ocular abnormalities on quality of life

Severe visual impairment is uncommon, approximately 6% of individuals with Fucosidosis experience vision loss.^1,5 

Good visual acuity is key for overall development and independence. The following suggestions can support an individual’s quality of life.⁸

• Early detection and treatment: Identifying ocular abnormalities early allows healthcare teams to maintain or improve vision and prevent more complex issues
• Informed decisions: After ocular exams, individuals and caregivers can make well-informed choices about treatments that best suit their needs
• Tailored care: Diagnosing ocular conditions helps healthcare teams, individuals and caregivers create specialised treatment plans, ensuring individuals receive the support they need for their eye health

Summary 

Ocular abnormalities associated with Fucosidosis include clouding of the cornea, dilated and tortuous retinal veins, and dilated and tortuous conjunctival vessels. A very small portion of individuals may experience visual loss. Healthcare typically prioritises protecting the eyes, reducing discomfort, and enhancing quality of life. Early detection and specialised care are key for managing ocular abnormalities associated with Fucosidosis.