Pathological myopia is not simply a high glasses prescription. It’s a condition where structural damage develops in the back of the eye, specifically in the retina and surrounding tissues, leading to progressive and sometimes irreversible vision loss. Unlike ordinary nearsightedness, which can be fully corrected with lenses, pathological myopia involves physical changes that glasses alone cannot fix.
The condition is defined by the presence of specific complications visible in the back of the eye: either a posterior staphyloma (an outward bulging of the eye wall) or myopic maculopathy at or beyond the stage of diffuse choroidal atrophy. Importantly, there is no strict prescription cutoff. While most people with pathological myopia have high prescriptions (typically beyond -5.00 diopters), the defining feature is structural damage, not the number on your lens.
How It Differs From High Myopia
High myopia and pathological myopia overlap but are not the same thing. High myopia refers to any prescription of -5.00 diopters or greater. Many people with high myopia live their entire lives with stable vision that corrects well with glasses or contacts. Pathological myopia is a subset where the eye’s elongation has caused tissue damage that threatens sight.
Posterior staphylomas, the hallmark finding, have been documented in eyes with normal axial length and in eyes shorter than 26.5 mm, which is only slightly longer than average. This is why clinicians moved away from using a specific prescription or eye length as the diagnostic boundary. The damage itself is what matters.
What Happens Inside the Eye
In a myopic eye, the eyeball is longer than normal from front to back. In pathological myopia, this elongation stretches the tissues at the back of the eye beyond their ability to adapt. The sclera, the tough white outer shell of the eye, thins as it stretches. At a cellular level, the fibers that give the sclera its strength break down faster than they’re replaced. Collagen production drops, while enzymes that degrade collagen become more active. The result is a sclera with less tensile strength, almost like a balloon that’s been inflated too far and can’t return to its original shape.
This thinning and stretching cascade inward. The choroid, a layer of blood vessels that nourishes the retina, becomes compressed and atrophied. Bruch’s membrane, a thin barrier between the choroid and retina, can crack under the mechanical stress. The retina itself, now draped over a misshapen surface, develops areas of thinning, splitting, or detachment. These changes are irreversible because the structural remodeling of the sclera cannot be undone.
The META-PM Staging System
Ophthalmologists classify the severity of damage using the META-PM system, which grades myopic maculopathy based on what’s visible in photographs of the back of the eye:
- Category 0: No myopic retinal lesions
- Category 1: Tessellated fundus, where the underlying blood vessel pattern becomes visible through a thinning retina
- Category 2: Diffuse choroidal atrophy, where the nourishing blood vessel layer has visibly thinned across a broad area
- Category 3: Patchy choroidal atrophy, with well-defined patches of tissue loss
- Category 4: Macular atrophy, where the central vision area has lost its supporting tissue
Pathological myopia is diagnosed at category 2 or higher, or when certain “plus lesions” are present regardless of category. These plus lesions include lacquer cracks, choroidal neovascularization, Fuchs spots, and posterior staphyloma.
Vision-Threatening Complications
The complications of pathological myopia are what make it dangerous, and they tend to build on one another over time.
Lacquer cracks are breaks in Bruch’s membrane caused by mechanical stretching. They appear as fine yellowish lines in the back of the eye and are unique to pathological myopia. On their own, they may not cause noticeable symptoms, but they create weak points where abnormal blood vessels can grow through.
Myopic choroidal neovascularization (CNV) is the most common cause of abnormal blood vessel growth beneath the retina in people under 50. These fragile new vessels leak fluid and blood into the retina, causing sudden blurring or distortion of central vision. This is the complication most likely to trigger urgent treatment.
Fuchs spots develop as a later consequence, often progressing from lacquer cracks or resolved CNV. They appear as pigmented scars in the macula and are strongly associated with central vision loss.
Myopic traction maculopathy occurs when the retina splits into layers or pulls away from the underlying tissue. Imaging studies show that the severity of this splitting predicts how quickly the condition worsens.
Who Is Most at Risk
Both genetics and environment play roles, though they interact in complex ways. Molecular studies have identified hundreds of common genetic variants that each contribute a small amount to myopia risk, measured through polygenic risk scores. Rarer single-gene mutations can cause high myopia in a more direct, deterministic way.
Environmental factors operate largely on top of genetic predisposition. Two exposures stand out. The first is intensive near work, particularly the kind associated with modern education systems: early schooling, heavy homework loads, and supplemental tutoring. The second is insufficient time outdoors. Higher light levels during daylight hours stimulate dopamine release in the retina, which appears to slow the eye’s elongation. The higher visual complexity of outdoor scenes may also play a protective role.
Geographically, the burden is heaviest in East Asia. In China, Japan, South Korea, and Singapore, 80 to 90% of 17- to 18-year-olds are myopic, and 10 to 20% are highly myopic. By contrast, high myopia prevalence among children in Africa is around 0.6%. In the United States, high myopia saw an eightfold increase between the early 1970s and early 2000s. Global projections estimate that by 2050, 10% of the world’s population will be highly myopic, a pool from which pathological cases emerge.
How It’s Monitored
Optical coherence tomography (OCT), a scan that creates cross-sectional images of the retina, is the primary tool for tracking pathological myopia over time. It can detect thinning of the choroid, splitting of retinal layers, fluid accumulation beneath the retina, and early signs of abnormal blood vessel growth before they cause symptoms.
Wide-field OCT is considered the best method for identifying posterior staphylomas, because it captures a broad enough view to show the full extent of the eye wall’s outward bulging. Choroidal thickness measured on OCT correlates with disease progression: thinner readings suggest more advanced damage. The presence of retinal splitting at baseline predicts a faster rate of worsening, which helps guide how frequently you need follow-up visits.
Treatment for Abnormal Blood Vessel Growth
When myopic CNV develops, the standard treatment is injections of medication that blocks the growth signal driving the abnormal blood vessels. These injections are given into the eye, typically starting with a single treatment followed by additional injections only if the disease remains active on follow-up scans.
Compared to older treatments like photodynamic therapy, these injections produce substantially better results. At one year, treated patients gained the equivalent of about 7 letters on a standard eye chart compared to photodynamic therapy. By two years, that advantage widened to about 13 letters. Patients receiving injections were also roughly 3.4 times more likely to gain three or more lines of vision at the two-year mark. Compared to no treatment at all, the benefit at six months was about 14 letters, with patients four times more likely to gain significant vision.
These results are encouraging, but treatment addresses the complication, not the underlying stretching. New episodes of CNV can occur, and the progressive atrophy of supporting tissue continues regardless of injection therapy.
Long-Term Vision Outlook
Pathological myopia is a leading cause of legal blindness in many countries, particularly in East Asia. A 10-year follow-up study of adults in Taiwan with high myopia (defined as -6.00 diopters or greater) found that 15.9% of those aged 60 to 69 and 26.2% of those aged 70 and older had vision of 20/200 or worse by the end of the study period. That threshold, 20/200, is the definition of legal blindness in the United States.
The risk of severe vision loss increases with age because the degenerative changes accumulate over decades. Someone diagnosed with pathological myopia in their 30s faces a longer window of potential progression than someone diagnosed at 60, making consistent monitoring over a lifetime essential. Early detection of treatable complications like CNV can preserve years of functional vision, even though the underlying condition itself cannot yet be reversed.