Pathological myopia is a rare type of shortsightedness where the eyeball continues to grow, becoming longer than it should be. This can occur at any age, but mostly between the ages of 30 and 40. In people under age 50, pathological myopia is often associated with the growth of leaky blood vessels that grow in the back of the eye, a condition your doctor may call choroidal neovascularization.
Commonly, people with the condition see a grey spot in the middle of their visual field or see straight lines as being distorted. The development of choroidal neovascularization is associated with serious impairment of vision and, in some cases, profound vision loss.
Other signs of pathological myopia are:
- Bending or distortion of straight lines
- Altered color perception
- Reduced contrast sensitivity
- Increasing loss of central vision, making it difficult to read, watch television, drive or recognize faces
Eventually pathological myopia can cause functional blindness, with only some peripheral sight remaining.
Pathological myopia can often be detected during routine eye examinations. The condition is diagnosed when eyeball elongation is greater than 26 mm or when your lens prescription exceeds specific parameters. If you are suspected of having this condition (or have already been diagnosed), you should have an annual check-up by an ophthalmologist to detect:
- Abnormal blood vessel growth
- Possible retinal detachment
Until recently, there was very limited treatment for pathologic myopia. One therapy, laser photocoagulation, uses heat from a thermal laser to destroy abnormal blood vessels. Unfortunately, it also damages healthy tissues in the retina and its light-sensitive cells. The result is some immediate, permanent vision loss.
Now there is a new, safer alternative that can preserve vision. Visudyne(R) (verteporfin for injection), also known as photodynamic therapy (PDT), is the first clinically proven therapy to treat pathological myopia.
Visudyne is currently approved for treating pathological myopia in over 40 countries, including the U.S. and Europe.
Visudyne is generally well tolerated and has a well-established safety profile. Infusion-related transient back pain occurred with Visudyne only at an incidence of 2.5%. Infusion induces temporary photosensitivity; patients should avoid exposure of skin and eyes to direct sunlight or bright indoor light for 5 days.
Severe vision decrease was reported within seven days in 1-5% of patients. Partial recovery occurs in some patients. Do not re-treat these patients until vision completely recovers to pretreatment levels and potential benefits and risks of subsequent treatment are carefully weighed.
The most frequently reported adverse events (10-30% incidence) were injection site reactions (including extravasation and rashes), blurred vision, decreased visual acuity, and visual field defects.