Pompe disease, also known as glycogen storage disease type II, is a rare genetic disorder caused by a deficiency in the enzyme acid alpha-glucosidase (GAA). This enzyme is responsible for breaking down glycogen, a sugar molecule stored in muscles, into glucose. When GAA is deficient or absent, glycogen accumulates in the muscles, including the heart, skeletal muscles, and respiratory system. Although primarily associated with muscular and respiratory issues, Pompe disease can also have notable ocular manifestations, which can play a key role in diagnosis and patient care.

Pompe disease exists in two main forms, which can affect ocular health in varying degrees:

• Infantile-Onset Pompe Disease (IOPD): This severe form appears shortly after birth and leads to rapid muscle weakness, heart enlargement, and respiratory problems. Ocular involvement, though less prominent, can arise early in the disease’s progression.
• Late-Onset Pompe Disease (LOPD): Symptoms in LOPD may not appear until later in childhood, adolescence, or adulthood. While muscle and respiratory symptoms predominate, ocular findings become more significant due to the slower progression of systemic symptoms.

Although the systemic effects of Pompe disease are widely recognized, ocular findings are less commonly discussed. Ocular involvement is generally non-specific and can affect various parts of the eye. The findings are subtle and do not typically impair vision early on, but certain signs can aid in the diagnosis of Pompe disease. These ocular manifestations include:

• Ptosis (Drooping of the Eyelid)

• • • Ptosis is one of the most common ocular findings in Pompe disease. It results from weakness in the levator palpebrae superioris muscle, which is responsible for lifting the eyelid. This condition may be mild at first, but can worsen over time, particularly in LOPD.
      • Clinical presentation: Unilateral or bilateral drooping of the upper eyelid.
      • Impact: Vision may be obstructed in severe cases, but more often, ptosis is a cosmetic concern.

• Ophthalmoplegia (Weakness or Paralysis of Eye Muscles)

• • • Ophthalmoplegia, or impaired movement of the eyes, can also occur in Pompe disease due to the accumulation of glycogen in the extraocular muscles. This can result in restricted eye movement, which may affect how patients perceive their environment.
      • Clinical presentation: Difficulty in moving the eyes in specific directions, leading to double vision (diplopia) in some cases.
      • Impact: While this condition can cause discomfort, it typically does not lead to blindness.

• Strabismus (Misalignment of the Eyes)

• • • Strabismus, or crossed eyes, occurs when the muscles that control eye movement are weakened or paralyzed. In Pompe disease, muscle dysfunction due to glycogen buildup can lead to misalignment of the eyes.
      • Clinical presentation: Eyes that do not move together in a coordinated way, potentially leading to double vision.
      • Impact: If untreated, strabismus can affect depth perception and vision development in children.

• Refractive Errors and Visual Acuity

• • • Although less common, some patients with Pompe disease may experience changes in refractive error, such as nearsightedness (myopia) or farsightedness (hyperopia). These are typically mild and not directly linked to the disease’s progression but can be secondary to muscle imbalances affecting eye structure.
      • Clinical presentation: Blurred vision due to improper focus of light on the retina.
      • Impact: Corrective lenses often resolve these issues, but underlying muscle dysfunction may persist.

• Optic Neuropathy

• • In rare cases, Pompe disease can affect the optic nerve, leading to optic neuropathy. This condition arises from glycogen accumulation in the optic nerve and surrounding tissues, potentially compromising the nerve’s ability to transmit visual signals to the brain.
    • Clinical presentation: Progressive loss of vision, changes in color vision, or visual field defects.
    • Impact: Optic neuropathy is a serious but rare manifestation of Pompe disease and can result in partial or complete vision loss if not addressed.

The ocular manifestations of Pompe disease can aid in its diagnosis, particularly in patients with milder or later-onset forms of the disease where systemic symptoms may be less pronounced. Early recognition of ptosis, ophthalmoplegia, and other eye abnormalities can prompt further genetic testing and enzyme assays for accurate diagnosis.

• Ocular Exams: Comprehensive eye exams, including tests for eye muscle function, visual acuity, and optic nerve health, are essential in detecting ocular involvement in Pompe disease.
• Genetic Testing: If ocular symptoms are present alongside muscular weakness, a genetic test for GAA mutations may confirm Pompe disease.

While enzyme replacement therapy (ERT) with alglucosidase alfa has revolutionized the treatment of Pompe disease, ocular symptoms may persist even with therapy. Therefore, managing ocular findings in Pompe disease involves a combination of the following:

• Surgical intervention: Ptosis may be corrected surgically if it significantly impacts vision. Similarly, strabismus surgery can help align the eyes and improve vision quality.
• Vision therapy: For patients with strabismus or ophthalmoplegia, vision therapy may help improve eye muscle coordination and reduce double vision.
• Corrective lenses: Refractive errors associated with Pompe disease can be managed with glasses or contact lenses.

Traumatic eyeball luxation carries a risk of several complications that can affect long-term vision and ocular health, including:

• Optic nerve damage: If the optic nerve is stretched or compressed during luxation, there may be irreversible damage, leading to permanent vision loss.
• Muscle damage: The extraocular muscles that control eye movement may be torn or damaged, resulting in diplopia (double vision) or strabismus (misalignment of the eyes).
• Exposure keratitis: Inability to fully close the eyelids can leave the cornea exposed, leading to dryness, irritation, and potentially vision-threatening corneal ulcers.
• Infection: The exposed globe is susceptible to infection, particularly if the eye has been damaged by a foreign object or contaminated during the injury.
• Enucleation: In severe cases where the globe is severely damaged or vision cannot be salvaged, enucleation (removal of the eye) may be necessary to alleviate pain or prevent infection.

Ocular findings in Pompe disease, although not the most prominent features, offer valuable insight into the diagnosis and management of this complex disorder. Recognizing the early signs, such as ptosis and ophthalmoplegia, can aid in timely diagnosis, leading to more effective management of both systemic and ocular symptoms. As treatments continue to advance, addressing these eye-related issues remains crucial in improving the quality of life for individuals with Pompe disease.

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