High myopia is defined by a refractive error of at least \(-6.00\) Diopters (D) or an axial length of 26.0 millimeters or greater. This severe form of nearsightedness fundamentally alters the structure of the eye. Retinal detachment (RD) occurs when the light-sensitive tissue at the back of the eye separates from its underlying supportive tissue. The structural changes associated with high myopia place individuals at a substantially higher risk for this sight-threatening event compared to the general population.
The Structural Link Between High Myopia and Detachment
The fundamental cause of increased risk is the physical elongation of the eyeball, which stretches the retina over a larger surface area. As the eye grows longer, the delicate retina becomes progressively thinner and more susceptible to damage, especially in the peripheral areas.
The stretching leads to the formation of weak spots or areas of abnormal thinning, such as lattice degeneration, which are prone to developing tears or holes. Furthermore, the vitreous humor—the gel-like substance filling the eye—liquefies and separates from the retina at a younger age in myopic eyes (posterior vitreous detachment). This separation can create abnormal traction that tugs on the fragile retina, causing a tear and initiating a rhegmatogenous retinal detachment.
Statistical Risk of Detachment in High Myopia
The risk of experiencing a retinal detachment is directly proportional to the degree of nearsightedness. Individuals with high myopia have a risk estimated to be approximately 10 times greater than that of people with normal vision, and up to 20 times higher for those with a refractive error of \(-5.00\) D or worse.
Eyes with myopia exceeding \(-6.00\) D showed an incidence of retinal detachment around 3.2%, significantly elevated compared to the 0.71% incidence observed in non-myopic eyes. The risk increases exponentially with the eye’s axial length; eyes longer than 28 millimeters face a steep rise in associated complications. This elevated risk is compounded following cataract surgery, where high myopes may have up to a seven-fold increased risk of subsequent retinal detachment compared to non-myopes.
Immediate Warning Signs and Symptoms
Recognizing the acute symptoms is of utmost importance because retinal detachment is a medical emergency. A common warning sign is the sudden appearance or dramatic increase in floaters—small specks or cobwebs that drift across the field of vision. These are caused by debris casting shadows on the retina as the vitreous gel changes.
Another sign requiring immediate attention is the sudden onset of flashes of light, known as photopsia, often seen in the peripheral vision. These flashes indicate that the vitreous gel is pulling on the retina, causing mechanical stimulation. A more advanced symptom is the perception of a shadow or a dark curtain moving across the field of vision, suggesting that the detachment is already underway.
Managing and Monitoring High Myopia
Proactive monitoring is the most effective defense against permanent vision loss in high myopes. Comprehensive eye examinations must be conducted regularly, often annually or semi-annually, using a fully dilated pupil. These exams allow the eye care professional to thoroughly inspect the peripheral retina, where tears and degenerations are most likely to occur.
Special attention is given to detecting weak areas like lattice degeneration or early retinal holes before they progress to a full detachment. If an examination identifies a retinal tear or a highly suspicious area of degeneration, prophylactic treatment such as laser retinopexy may be performed to seal the edges and prevent fluid accumulation. Individuals should also discuss protective measures, such as wearing protective eyewear for sports, to minimize the risk of eye trauma that could precipitate a tear.