Eye Health Refractive Errors

Refractive Errors

The retina is a layer at the back of the eyeball containing the light-sensitive tissue that triggers nerve impulses that pass via the optic nerve to the brain to form a visual image. A clear vision required light to be focused on the retina. Refractive errors refer to conditions in which the eye is unable to focus light onto the retina. There are 4 common types of refractive errors.

  1. Myopia
  • Also known as shortsightedness, is a condition in which light is focused in front of the retina.
  • A person with shortsightedness has a clear near vision but a poor distance vision. The typical complaint of shortsighted people is the difficulty in seeing distant objects clearly such as the whiteboard at school and road signs or in recognizing people.
  • Myopia is becoming the most common refractive error among children. Myopia typically progresses throughout the young age as the body grows.
  • Myopia is influenced by both genetic and environmental factors. Having one or both parents with myopia and too much time reading up close or screen time can increase the risk of developing myopia.
  • A person with high myopia is exposed to an increased risk of retinal detachment, glaucoma and macular degeneration.
  • Some people cannot realize the problem until it progresses, but an eye examination by an optometrist will reveal the problem from the very early onset.
  • There is so far no cure or prevention for myopia. However, there are measurements that can correct your vision and medical breakthroughs that can slow down myopia progression. Our optometrist can advise you the latest developments and treatments and whether they would be appropriate for you

 

  1. Hyperopia
  • Longsightedness is a condition in which light is focused behind the retina.
  • Generally, people with little hyperopia do not have complaints with their vision in distance but may have blurred vision at near. The greater the hyperopia, the harder it is to focus. ┬áSignificant hyperopia may result in blurry visions at both distance and near.
  • The typical complaints are tired eyes and headache after a period of visual work. Reading and schoolwork are usually affected.
  • Low hyperopia found in kids is usually not problematic as their eye muscles can adjust to compensate. However, children who experience headache and eyestrain with constant concentration at near need to see an optometrist.
  • Glasses, eye exercise or regular eye break from close up work can relieve symptoms of longsightedness.

 

  1. Astigmatism
  • Is a focusing error leading to asymmetric blur. That is to say, some directions in an image are more out of focus than others.
  • Usually caused by the irregularity or imperfection of the cornea (the front surface of the eye). Instead of having a nice spherical shape, the astigmatic cornea has an oval shaped, making light passing through it bend differently in different directions.
  • A person with astigmatism has difficulty seeing objects at both distance and near. The image can sometimes be described as shadowy. Even a low amount of astigmatism can cause headache and fatigue or may reduce concentration.
  • Astigmatism can be hereditary or acquired from aggressive rubbing on the cornea, especially in children who has hay fever.
  • Astigmatism can occur alone or in combination with longsightness and shortsightness. Most types of astigmatisms can be corrected with glasses or contact lenses.

 

  1. Presbyopia
  • A common condition of the eye that makes vision difficult at a normal reading distance due to the continued growth of the biological lens inside the eye, which is part of ageing. The distance vision is not affected.
  • It typically occurs around the age of 40-50 years old and progresses from the age of 45 to 65 years, hence people find their prescription changes significantly within this period.
  • As we are ageing, the lens in the eye loses its flexibility in changing its shape hence the eye loses its capacity to change its focus from distance to near.
  • A person with presbyopia usually finds it hard to do close tasks such as reading books or sewing. They tend to put things further away from the eyes to obtain better visions.
  • Presbyopia can be corrected with glasses, which are designed for near focus only. That is to say, correction for presbyopia creates clear close vision but blurry distance vision. Therefore, different glasses for different tasks may be required.
  • Multifocal or Bifocal glasses are usually the best solution in this case to allow this person to have both corrections at Distance and near in a single pair of glasses.
  • Moreover, our optometrist will provide you with the best advice and glasses designed that will bring you the best comfort.