Overview

Floating-Harbour Syndrome is a rare genetic disorder resulting from mutations in the SRCAP gene. Individuals with Floating-Harbor Syndrome often present with various conditions including; skeletal malformation, cognitive impairments and distinctive facial features.¹ This article will explore ophthalmologic issues associated with Floating-Harbor Syndrome, along with their diagnosis and management strategies, offering a clear and comprehensive overview. 

Ophthalmological conditions associated with Floating-Harbor Syndrome

The following sections will discuss structural and functional ophthalmological issues related to Floating-Harbor Syndrome. 

Structural ophthalmological anomalies

Structural eye abnormalities are physical malformations which can affect how the eye or eyes look or work. The list below gives details of associated structural ophthalmological issues with Floating-Harbor Syndrome: 

• Enopthalomos, also referred to as ‘deep-set eyes.’² 
• Long eyelashes^1,3
• Chorioretinal coloboma which is characterised by a defect in the retina and the choroid layers of the eye.⁴ Sometimes individuals with chorioretinal coloboma will not notice any visual symptoms, however some individuals can experience visual field loss⁷ 

Functional ophthalmological issues

Floating-Harbor Syndrome can have associated functional ophthalmological issues which can affect how well an individual can use their eye or eyes. The list below gives details of associated functional ophthalmological issues with Floating-Harbor Syndrome: 

• Refractive error - This term refers to the natural shape and size of an individual’s eye. An individual’s refractive error can be corrected with a glasses or contact lens prescription. Uncorrected refractive error can cause reduced visual acuity. The most common type of refractive error reported in Floating-Harbor Syndrome is hyperopia, which indicates that an individual may find their vision up close may be blurry
• Strabismus - This is where one eye or both be misaligned from the visual axis. Depending on the amount of misalignment and classification of the type of misalignment will dictate if it will impact an individual's visual acuity and or binocular vision

Prevalence of ophthalmological issues 

Due to the small sample sizes in many case studies examining prevalence data is limited. Overall, case studies indicate that strabismus and hyperopia are rarely observed in Floating-Harbor Syndrome compared to features like long eyelashes and enophthalmos.⁶ 

Diagnosis and treatment approaches of ophthalmological issues 

Structural and functional ophthalmological issues can be investigated and diagnosed by utilising a variety of ophthalmological examinations. It is recommended that individuals with Floating-Harbor Syndrome should have an annual ophthalmological assessment.⁵ The following sections will give an overview of specific ophthalmological examinations to assess structural and functional ophthalmological issues discussed above. 

Examining the front part of the eye 

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

Examining the back of the eye 

The 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, clinicians in the ophthalmology team may put dilating drops in an individual's eyes to dilated (widen) the pupil. A dilated pupil can provide a better view for a clinician to examine the optic nerve and the retina. 

Assessing visual fields 

A visual field assessment examines the extent to which each eye can see in each direction whilst maintaining eye contact straight ahead. During the assessment an individual is requested to stare at a target straight ahead, this can be done with each eye separately as well as both eyes together. A light is presented in different sizes as well as different levels of brightness which also enables an assessment of the sensitivity across an individual’s visual field. 

Assessing vision

Visual acuity can be assessed by asking an individual to look at an eye chart and different distances. This is conducted with both eyes open and each eye individually. This will determine the level of vision. 

Assessing for refractive errors 

Refractive error examination determines if a glasses or contact lens prescription is required for an individual. This is important as this can impact visual acuity development especially in childhood. Amblyopia is referred to when vision in one or both eyes is impacted. This can be caused by functional ophthalmological issues such as strabismus, refractive error or even broader structural ophthalmological issues.⁸ 

Eye movement assessment 

To assess for strabismus an assessment called ocular motility can be conducted to assess how well the eyes move as a pair as well as individually. The assessment is conducted by a clinician, who uses a light to examine eye movement by instructing an individual to follow the light in different directions. During the examination, eye muscle function can be examined in addition with the degree of eye alignment in relation to the visual axis. 

Impact on quality of life

Depending on the type and severity of ophthalmological diagnosis, quality of life can be impacted. Therefore, it can be important to understand ophthalmological issues associated with Floating-Harbor Syndrome, so individuals can be supported appropriately. A good level of visual acuity is important for overall development and independence in life. The following steps can be taken into consideration to support a positive impact on an individual’s quality of life: 

• Early detection and treatment - Checking for potential eye issues early on can help healthcare teams to maintain, and improve vision and or prevent further complex ophthalmological issues
• Informed decisions - Upon ophthalmological investigation individuals and caregivers can be supported so they can advocate for treatments that are appropriately suited
• Tailored care - Diagnosing eye issues can assist healthcare teams, caregivers and individuals to collaborate upon specialised treatment plans to suit an individual’s needs
• A specialised plan can ensure individuals are supported with their ophthalmological issues

Summary 

Floating-Harbor Syndrome is a rare genetic condition that can have associated ophthalmological issues. Unlike common features such as skeletal abnormalities, Floating-Harbor Syndrome reports a limited number of cases in association with ophthalmological issues. Of the cases reported common ophthalmological issues included deep-set eyes and long eyelashes. Hyperopia and strabismus are infrequently reported. However, it is recommended that an individual who is diagnosed, or under investigation for Floating-Harbor Syndrome to have an annual ophthalmological examination. This can aid in the early detection and intervention of ophthalmological issues.