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Dr. ICL LEE DONG HOON
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Avellino corneal dystrophy is a hereditary disorder in which abnormal protein accumulates in the stroma, the transparent part of the outermost corneal tissue, causing progressive clouding over time. It is caused by a mutation in the TGF-β1 gene and is inherited in an autosomal dominant manner.
Type GCD 1 is widespread across Europe, while Type GCD 2, first described in 1988, was discovered in four patients who shared a common ancestor from the Avellino region of Italy, giving the disease its name, Avellino Corneal Dystrophy. However, subsequent research has shown that this condition can also occur in populations without Italian heritage. Today, it is the most common form of corneal dystrophy in certain Asian countries, particularly South Korea and Japan.
There are multiple forms and subtypes of corneal dystrophies besides granular dystrophy, but in Korea, Avellino is overwhelmingly common. Therefore, I will focus on Avellino rather than other types (such as lattice corneal dystrophy (LCD), macular corneal dystrophy (MCD), fleck corneal dystrophy (FCD), Schnyder corneal dystrophy (SCD), posterior amorphous corneal dystrophy (PACD), etc.), which all have subtly different clinical features. If patients with other forms of corneal dystrophy visit for consultation, I will provide detailed information individually. The severity of Avellino corneal dystrophy varies greatly among individuals. As seen in the examples below, even among people in their 20s, the degree of opacity varies widely. Moreover, even within the same individual, the size, depth, and density of opacities may differ, and vision varies depending on how much the opacity covers the visual axis (usually referring to the inner area of the pupil where light passes through).
Age 27, Best Corrected Vision 0.5/0.6 : Although the opacity is severe, the vision is relatively decent.
Age 28, Current Best Corrected Vision 1.0/1.0 : There are numerous opacities, but they are not dense.
Unaided Vision 1.0/1.0 (Received ICL Surgery 5 years ago) : Although the opacity is dense, there are few of them, and crucially, they are outside the visual axis, near the periphery of the pupil.
Age 26, Best Corrected Vision 1.0/1.0 : There is almost no opacity, detectable only under a microscope.
of Avellino corneal dystrophy in Korea varies by study, ranging from 1 in 870 to 1 in 1,320.
It is not a rare disease; in contrast to rare conditions with a prevalence of 1 in 10,000 or more, Avellino is relatively common. This is because it has an autosomal dominant inheritance pattern, making it easy to pass down, and it is non-lethal. Unlike conditions with a high fatality rate, which tend to diminish over generations, this condition persists as it has no effect on health outside the eyes, and symptoms often progress slowly, affecting vision only in middle age or later, allowing for natural transmission of the gene. It is similar to how the common cold virus, which is less fatal, has survived longer than deadly pathogens like the plague or smallpox.
Avellino corneal dystrophy is inherited in an autosomal dominant pattern, occurring in families. Unsurprisingly, homozygous individuals (both parents have Avellino) tend to have larger, more fused, and more severe corneal opacities than heterozygous individuals (only one parent has Avellino).
< Heterozygous: If only one parent has Avellino >
< Homozygous: If both parents have Avellino >
The probability of a child inheriting the disease is 50% with one affected parent, regardless of gender. With both parents affected, the probability increases to 75%, still with no gender difference. In most cases, individuals with Avellino are heterozygous. Autosomal dominant inheritance means that men and women are equally likely to inherit the condition, with a 50% chance for a child to inherit the gene from an affected parent. Let’s say a mother has Avellino. In this case, her child has a 50% chance of inheriting her affected chromosome. The child’s sibling also has a 50% chance of inheriting Avellino, regardless of the sibling's status. This inheritance pattern is independent; if I do not inherit the Avellino gene, my descendants will not inherit it either.
Avellino corneal dystrophy is typically diagnosed when an ophthalmologist detects characteristic corneal opacities incidentally during a microscopic examination. If suspicious findings are observed, a simple genetic test can confirm the diagnosis by identifying mutations in the TGF-β1 gene.
< The severity of the opacities
can be classified from mild to severe. >
Most patients with Avellino corneal dystrophy initially have no symptoms or only experience mild glare and halos around lights. As the disease progresses, unique symptoms such as decreased vision and recurrent corneal pain (a phenomenon known as recurrent corneal erosion, where the corneal epithelium above deposits becomes painful when it detaches) may occur, usually only in severe cases and often in the later stages of the disease, typically in individuals in their 50s or 60s. Therefore, it is rare for patients to visit the hospital due to subjective symptoms. Instead, most people discover they have Avellino corneal dystrophy unexpectedly during visits for other reasons, such as conjunctivitis, vision testing, or preoperative exams for refractive surgery, which often surprises them. However, in most cases, symptoms are not severe, and the prognosis is not particularly poor, so there is no need to feel prematurely discouraged or hopeless.
It is natural to be concerned about the disease itself, but it is more important to respond calmly, undergo genetic testing to identify any family members with the gene, and monitor disease progression with annual check-ups. If the disease progresses slowly, most patients can live without treatment and can even undergo vision correction safely with ICL lens implantation.
In addition to the traditional method of comparing enlarged corneal images over time to check for changes in opacity size, position, or number, Dr. ICL Eye Clinic also utilizes corneal tomography with devices like CASIA2, which provides cross-sectional images of the cornea. This is beneficial in determining the depth of treatment needed if therapeutic laser corneal opacity removal or partial corneal transplant is considered in the future.
Since Avellino corneal dystrophy is a genetic disorder, there is no fundamental cure. However, in cases of mild Avellino that do not significantly impair vision or lead to frequent corneal injuries, treatment is generally unnecessary for the first few decades of the disease’s progression. Still, it is important to avoid habits that can damage the cornea, such as wearing contact lenses or rubbing the eyes, as corneal injuries can accelerate disease progression.
If recurrent erosions develop, artificial tears or ointments can help relieve dryness and irritation.
Phototherapeutic keratectomy (PTK) can smooth the corneal surface and reduce some opacity for patients with recurrent corneal erosions or severe surface irregularities. However, since opacity may recur after some time, PTK should be considered a temporary solution rather than a fundamental treatment. If corneal opacity progresses significantly, causing substantial vision loss, corneal transplantation (penetrating keratoplasty (PKP), deep anterior lamellar keratoplasty (DALK), or femtosecond-assisted lamellar keratoplasty (FALK)) may be considered.
Precautions for Avellino Patients
The most crucial point for patients with Avellino corneal dystrophyis to absolutely avoid any form of laser refractive surgery, such as LASIK, LASEK, or SMILE. Trauma from the surgery can accelerate the formation of corneal deposits, leading to rapid vision deterioration.
Avellino dystrophy is primarily characterized by small, separated white granular opacities in the corneal stroma. Typically, there are clearly transparent areas between these deposits. The granules are usually located in the central part of the cornea (within a 6mm diameter from the center), with few deposits in the peripheral area (outside a 9mm diameter). These deposits resemble broken breadcrumbs or snowflakes. As the disease progresses, the size and number of opacities increase. However, since patients can see through the transparent spaces between the opacities, vision may remain relatively good despite the severity of the opacities.
Avellino Corneal Dystrophy Before Laser Vision Correction Surgery
Although there may be numerous opacities, corrected vision may still reach 1.0 due to visibility through the transparent areas between them.
However, over time, corneal opacity gradually extends into these transparent spaces, which become less clear with age. This terminal stage of opacity, occurring over decades, is typically thinner and situated closer to the corneal surface than the dense white granules. Once the transparent areas—previously acting as "pinholes" between the granular opacities—become opaque, vision deteriorates rapidly, making it seem to the patient as though the disease has suddenly progressed. Even though the patient has had the condition for decades, it may feel like a sudden new development within months. That said, only a subset of patients progress to this end stage, so those diagnosed with Avellino should not immediately assume the worst-case scenario.
If an Avellino patient, especially a younger one with a mild phenotype where the cornea appears nearly transparent with minimal opacities, unknowingly undergoes laser vision correction (such as LASIK or LASEK), severe complications can arise. This is similar to how keloid-prone individuals may develop irregular scarring at the incision site; in Avellino patients, opacity and protein deposits form at the laser-treated area. Laser vision correction inherently involves creating a wound in the cornea, specifically by ablating tissue to reshape it. This creates unavoidable injury, and the procedure is based on the assumption that natural wound healing will restore the treated area smoothly. However, for individuals with keloids, severe dry eye, connective tissue diseases (such as lupus or rheumatoid arthritis), certain metabolic diseases, or conditions like Avellino with impaired wound healing, the recovery may result in scarring rather than healing. Particularly, opacities in the previously transparent areas may increase rapidly, as if decades of Avellino progression occurred in an instant.
For Avellino Patients in Their 20s
Pre-laser corrected
vision of 0.9.
Although there is some opacity, it is minimal and located away from the central visual axis. The transparent areas between the opacities are well-maintained, so there is little negative impact on vision.
Post-LASIK, maximum corrected vision of 0.2,
unaided vision unmeasurable.
Dense opacity developed as scarring appeared at the laser-treated area, almost eliminating the transparent areas between the opacities.
Case of a 44-Year-Old Male Patient
This patient underwent LASIK 8 years ago without issues, but recently presented with severe glare and halos at night. Maximum corrected vision is 0.5. Especially in the optical zone, the laser-treated area near the central visual axis has developed a circular scar with dense opacities, making it difficult to expect improvement in vision.
After an urgent phototherapeutic keratectomy (PTK) procedure to smooth the superficial opacities, a week later, transparent areas between the opacities increased slightly. However, due to the irregular astigmatism caused by corneal ablation, the maximum corrected vision decreased to 0.2, and the patient eventually needed corneal transplant surgery.
"Safe and Effective Vision Correction for Avellino Corneal Dystrophy"
ICL lens implantation is the only treatment that can achieve uncorrected vision nearly equal to maximum corrected vision without worsening the corneal condition in mild cases of corneal dystrophy.
Many Avellino patients who have received ICL surgery continue to do well, and regular ICL check-ups allow for careful monitoring of any changes in their Avellino status. This helps monitor the disease, which can be easily overlooked due to the lack of symptoms. An important consideration for ICL vision correction in Avellino patients is that residual astigmatism cannot be corrected with laser treatment. Therefore, special care must be taken with the design and implantation of the Toric ICL to ensure it remains in a fixed position. Proper ICL sizing is the top priority. Just as with a ring that fits securely without rotating or slipping, the size of the ICL lens is crucial. Precise measurement of the intraocular space and the selection of a perfectly fitting lens size are the foundational steps that require careful attention.
Case of a 35-Year-Old Avellino Patient Maintaining 1.2 Vision for 10 Years After ICL Surgery
Most opacities are located away from the central visual axis, so they have minimal impact on vision and are expected to remain stable over time. The patient's 70-year-old mother also has Avellino corneal dystrophy without any significant vision impairment, suggesting a mild phenotype within the family. Consequently, the patient has achieved average expected ICL vision with high quality, leading to a satisfactory outcome.
The progression and severity of Avellino corneal dystrophy vary widely among individuals.
Severe vision loss is rare, so there is generally no need for excessive concern. While some individuals may remain relatively asymptomatic throughout their lives, others may experience significant vision loss and recurring painful symptoms. By undergoing precise ophthalmic examinations to understand the current condition and monitoring progression with regular check-ups, one can reduce undue worry and receive timely treatment if needed.
However, if the cornea is damaged due to inflammation, trauma, disease, or laser surgery, opacities can worsen rapidly, so caution is necessary. Although glasses are the best option, many people wear contact lenses due to professional or environmental reasons. Since contact lenses are a major cause of keratitis, it is generally advisable to opt for ICL lens implantation, which does not harm the cornea, instead of continuing with contact lenses.
