Congenital Hereditary Endothelial Dystrophy (CHED) is a rare, inherited eye condition impacting the cornea. This condition leads to progressive clouding of the cornea, which can significantly impair vision from birth or early childhood.
Understanding Congenital Hereditary Endothelial Dystrophy
CHED affects the corneal endothelium, the innermost layer of the cornea. This layer is responsible for maintaining the cornea’s clarity by pumping excess fluid out of the corneal tissue. When the endothelium is dysfunctional due to CHED, fluid accumulates within the cornea, causing edema. This fluid buildup causes the cornea to swell and become hazy, leading to clouding.
The genetic basis of CHED is typically an autosomal recessive inheritance pattern. This means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the condition. Both parents can be carriers of the gene without showing any symptoms themselves. The primary gene associated with CHED is SLC4A11, which encodes a transmembrane protein involved in ion transport within cells. Mutations in this gene disrupt the normal function of the corneal endothelial cells, leading to their degeneration and corneal edema.
Recognizing the Signs and Securing a Diagnosis
Signs of CHED typically appear in infants and young children. These include bilateral corneal clouding, which makes the eyes appear hazy or milky. Affected children often exhibit light sensitivity, known as photophobia, and may experience excessive tearing. In some cases, involuntary eye movements, or nystagmus, can also be present.
The diagnostic process for CHED usually involves a comprehensive eye examination. This examination often includes a slit-lamp examination, which allows the doctor to view the individual layers of the cornea in detail. Pachymetry, a test to measure corneal thickness, is also performed, as corneas affected by CHED can be two to three times thicker than normal. Genetic testing for mutations in the SLC4A11 gene confirms the diagnosis.
Treatment Approaches and Management
The primary treatment for CHED is corneal transplantation to restore corneal clarity and improve vision. The type of corneal transplant performed can vary, but penetrating keratoplasty (PK), a full-thickness corneal transplant, is often used, especially in infants. This procedure replaces the diseased corneal tissue with healthy donor tissue.
While surgical intervention is the main approach, some supportive, non-surgical management options may be considered, such as hypertonic saline drops to reduce corneal swelling. However, these drops offer limited effectiveness compared to surgery. Early intervention through transplantation is important for promoting proper visual development and preventing amblyopia, a condition where the brain favors one eye due to poor vision. The goal of these treatments is to provide the best possible visual outcome for the child.
Living with the Condition and Long-Term Outlook
Following a successful corneal transplantation, individuals with CHED can experience significant visual improvement. However, ongoing post-operative care is necessary to manage potential complications, such as graft rejection or glaucoma. Regular follow-up appointments with an ophthalmologist are important to monitor the health of the transplanted cornea.
The long-term prognosis for individuals with CHED who undergo successful transplantation is generally favorable, with many experiencing improved quality of life. Visual rehabilitation and support for overall development are also important aspects of managing the condition long-term. This includes addressing any visual impairments that may persist after surgery and supporting the child’s learning and social development.