"Bad" eyesight is generally defined as anything less than 20/20 vision, requiring correction for clear vision and safe navigation. However, the severity of vision impairment varies greatly.
Understanding Eye Power (Prescription)
Your eyeglass or contact lens prescription indicates the correction needed to achieve optimal vision. The numbers represent the degree of nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. These are measured in diopters.
Severity Levels:
- Mild: Nearsightedness between -0.25 and -2.00 diopters or farsightedness of a similar magnitude. Blurry distance vision may be experienced.
- Moderate: Nearsightedness between -2.25 and -5.00 diopters or farsightedness within a comparable range. Blurred distance vision is more pronounced. A prescription of -1.75, for example, indicates moderate vision impairment.
- Severe: Nearsightedness exceeding -5.00 diopters or farsightedness of a similar degree. Extremely blurry distance vision is common. Severe myopia ranges from -6.00 to -9.00 diopters, while extreme myopia is > -9.00 diopters.
Factors Affecting Severity:
Several factors influence how "bad" your eyesight is, and a single number on a prescription doesn't encompass the full picture. These factors include:
- The specific numbers in your prescription: The higher the diopter, the more correction is needed.
- The presence of astigmatism: Astigmatism, an uneven curvature of the cornea, further complicates vision correction.
- Individual tolerances: Some individuals tolerate lower vision levels better than others.
- Age-related changes: Conditions like presbyopia affect focusing ability and worsen near vision with age.
Conclusion
The "badness" of eye power is relative and depends on multiple factors beyond a simple numerical prescription. It's crucial to consult an eye care professional for a proper diagnosis and personalized management plan.
