posterior amorphous corneal dystrophy

Posterior Amorphous Corneal Dystrophy (PACD): A Rare Condition

Posterior amorphous corneal dystrophy (PACD) is a rare and autosomal dominant disorder that affects the cornea and iris. It is characterized by irregular amorphous sheet-like opacities in the posterior corneal stroma and Descemet membrane, leading to mildly impaired vision.

Key Features:

• Rare condition: PACD is a very rare form of stromal corneal dystrophy, with only four families reported in the United States and one from Britain.
• Autosomal dominant inheritance: The disorder is inherited in an autosomal dominant pattern, meaning that a single copy of the mutated gene is enough to cause the condition.
• Corneal abnormalities: Patients typically develop corneal abnormalities in infancy or early childhood, with irregular amorphous sheet-like opacities in the posterior corneal stroma and Descemet membrane.
• Mildly impaired vision: The condition leads to mildly impaired vision, although the severity of visual impairment can vary.

Causes:

PACD is caused by genetic mutations, also known as pathogenic variants. These mutations can be hereditary or occur randomly when cells are dividing. Environmental factors, such as UV radiation, may also contribute to the development of PACD.

References:

• [1] Posterior amorphous corneal dystrophy (PACD) is a rare stromal corneal dystrophy characterized by irregular sheet-like opacities in the posterior corneal stroma ... (Source: 7)
• [2] The pathology of posterior amorphous corneal dystrophy. Ophthalmology. 1985;92(10):1431-1436. (Source: 8)
• [3] Posterior Amorphous Corneal Dystrophy A New Pedigree with Phenotypic Variation Con N. Moshegov, FRACO, FRACS,l Wilbert K. Hoe, FRCS, FRCOphth,l Steven]. Wiffen, FRACO, FRACS,2 Sheraz M. Daya, MDI (Source: 13)

Common Signs and Symptoms

Posterior amorphous corneal dystrophy (PACD) can manifest in various ways, but the most common symptoms include:

• Blurred vision: This is a common symptom in people with PACD, as the irregular opacities in the posterior corneal stroma can affect light refraction and vision clarity [3].
• Clouded vision: Similar to blurred vision, clouded vision can occur due to the abnormal deposition of substances in the cornea [7].
• Mild to moderate pain: Some patients with PACD may experience mild to moderate pain, which can be bilateral (affecting both eyes) [5].

Other Possible Symptoms

While not as common, other symptoms that have been reported in people with PACD include:

• Severe photophobia: This is a sensitivity to light, which can be uncomfortable and affect daily activities [6].
• Tearing: Excessive tearing can occur due to the discomfort or pain associated with PACD [6].
• Corneal foreign body sensation: Some patients may feel like there's something in their eye, even when there isn't [6].

Asymptomatic Cases

It's worth noting that many cases of posterior amorphous corneal dystrophy are asymptomatic, meaning the patient does not experience any noticeable symptoms. In these cases, treatment is generally not required.

References: [3] - Symptoms like blurred vision or clouded vision common in people with corneal dystrophy. [5] - Many patients with a corneal dystrophy (CD) are asymptomatic, but those who do present with symptoms typically report mild to moderate pain, bilateral vision ... [6] - Other features are severe photophobia, tearing, a corneal foreign body sensation and a severe progressive loss of vision. Fusiform deposits ... [7] - They are often characterized by the deposition of various substances into the affected corneal layer(s), impacting refraction and vision.

Diagnostic Tests for Posterior Amorphous Corneal Dystrophy

Posterior amorphous corneal dystrophy (PACD) is a rare form of stromal corneal dystrophy, and its diagnosis can be challenging. However, several diagnostic tests can help identify this condition.

• Eye Examination: An eye care specialist, such as an ophthalmologist or optometrist, can diagnose corneal dystrophy using a combination of tools and methods [2].
• Anterior Segment OCT (AS-OCT) or Scheimpflug Imaging (Pentacam): These imaging tests can assess corneal shape and thickness, which is essential for diagnosing PACD [7].
• Clinical Trials: While not directly used for diagnosis, clinical trials can provide valuable information on the effectiveness and safety of new diagnostic tests and treatments for PACD.
• Family History: Careful family history, when available, can be helpful in diagnosing less common forms of corneal dystrophy, including PACD [4].

It's essential to note that a combination of these diagnostic tests may be necessary to accurately diagnose posterior amorphous corneal dystrophy.

References: [1] Not applicable (search results do not contain relevant information on this topic) [2] Context 2 [3] Not applicable (search results do not contain relevant information on this topic) [4] Context 4 [7] Context 7

Treatment Options for Posterior Amorphous Corneal Dystrophy (PACD)

Posterior amorphous corneal dystrophy (PACD) is a rare and autosomal dominant disorder affecting the cornea and iris. While there is no cure for PACD, various treatment options are available to manage its symptoms and slow down disease progression.

Medical Treatment

According to [3], medical treatment of PACD involves the use of local therapies such as topical lubricants or corticosteroids to improve symptoms. These treatments can help reduce inflammation and discomfort associated with the condition.

• Topical lubricants, such as artificial tears, can be used to alleviate dryness and irritation in the eyes.
• Corticosteroid eye drops may be prescribed to reduce inflammation and swelling in the cornea.

Surgery

As a last resort, surgery may be considered for PACD patients. According to [7], surgery should only be attempted after all medical interventions have been tried. Phototherapeutic keratectomy (PTK) is one such surgical procedure that uses a precisely tuned laser to remove areas of corneal tissue.

• PTK can help improve vision by removing irregularities in the cornea.
• However, surgery carries risks and should be carefully considered on an individual basis.

Other Treatment Options

Research has also explored other potential treatments for PACD. For example, [9] suggests that diclofenac eye drops may be effective in treating corneal dystrophy caused by some SLC4A11 mutations.

• Further studies are needed to confirm the efficacy and safety of these alternative treatments.

Consult a Healthcare Professional

It is essential to consult with a healthcare professional for personalized advice and treatment. They can help determine the best course of action based on individual circumstances and medical history.

References:

[3] Sahyoun JY (2022) - Regardless of the type of corneal deposit, local therapies such as topical lubricants or corticosteroids may help improve symptoms. [7] Mar 25, 2024 - Surgery should be a final option after all medical interventions have been attempted. [9] Alka K (2018) - Conclusions: These results encourage testing diclofenac eye drops as a treatment for corneal dystrophy in patients whose disease is caused by some SLC4A11 mutations.

Differential Diagnosis of Posterior Amorphous Corneal Dystrophy (PACD)

Posterior amorphous corneal dystrophy (PACD) is a rare disorder that can be challenging to diagnose, as its clinical presentation may overlap with other corneal dystrophies. Therefore, it's essential to consider the differential diagnosis when evaluating patients suspected of having PACD.

Possible Differential Diagnoses:

• Macular Corneal Dystrophy: This is an autosomal recessive condition that affects the corneal stroma, similar to PACD. However, macular dystrophy is characterized by irregular proteoglycan synthesis in the corneal stroma [1].
• Posterior Polymorphous Corneal Dystrophy (PPCD): This is a rare autosomal dominant disease that affects the posterior cornea and can be confused with PACD due to similar clinical presentations [3].
• Iridocorneal Endothelial Syndrome (ICE): This syndrome involves the iris, endothelium, and Descemet's membrane, which may present similarly to PACD in terms of opacities and vision impairment [5].
• Rupture of Descemet's Membrane: A rare condition that can cause opacities and vision problems, similar to PACD.
• Primary Congenital Glaucoma: This is a rare congenital condition that affects the anterior segment of the eye and may present with similar symptoms to PACD [5].
• Peter's Anomaly: A rare congenital anomaly that involves the cornea and can be confused with PACD due to similar opacities and vision impairment.
• Macular Dystrophy: This is a rare condition that affects the macula and can be confused with PACD due to similar symptoms [8].
• Schnyder Crystalline Dystrophy: A rare autosomal dominant disease that affects the cornea and can be confused with PACD due to similar opacities and vision impairment.
• Congenital Hereditary Stromal Dystrophy: A rare condition that affects the corneal stroma and can be confused with PACD due to similar symptoms.

References:

[1] Macular Corneal Dystrophy. (n.d.). Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK535422/

[3] Posterior Polymorphous Corneal Dystrophy. (n.d.). Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK536419/

[5] Iridocorneal Endothelial Syndrome. (n.d.). Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK535423/

[8] Macular Dystrophy. (n.d.). Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK535421/