Types of myopia
There are several types of myopia, with different degree and complications. Types of myopia include:
1- Simple myopia: It is the most common variant of myopia; the degree of simple myopia usually ranges from minus one to minus three (-1 to -3) diopters.
2- Moderate myopia: In moderate myopia,myopia degree ranges from minus three to minus six (-3 to -6) diopters. Patients in this category are more liable to develop conditions like glaucoma, and pigment dispersion disease.
3- High or degenerative myopia: It is a serious and rare type of myopia, andaffects 2% of populations. In this type, the myopia degree exceeds minus six (-6) diopters. In degenerative or pathological myopia, the concern comes from the substantial risk of developing different serious conditions such as: retinal detachment, glaucoma, cataract, macular degeneration, and even complete loss of vision could happen. In degenerative myopia, the patient’s visual acuity is deteriorated quickly, constantly, and do not stabilize in early adulthood as in simple myopia.
4- Night myopia: One of the common types of myopia, which causes decrease in the visual acuity at the night or any similar dim-light conditions. Unlike the previous types, night myopia can occur to a healthy individual with no refractive errors. This condition is thought to be because of the inability of the accommodation system of the eye to adapt from high light conditions to dim light conditions.
5- Pseudo myopia: A temporary condition due to excessive near work conditions like reading or working on computers; the excessive near work causes stress to the eye and its accommodation system. Taking rest every while can resolve this problem, but continuous stress on the eye increases the risk of developing a fixed myopia.
6- Instrumental myopia: Atemporary condition occurs when using instruments like microscope, vision would be blurry for a while after using the microscope for long time.
7- Induced myopia: Instrumental myopia is a type of myopia that can be results from use of specific medications, and diseases like diabetes mellitus and oxygen toxicity.
