Defects Of Human Eye And How To Choose Glasses And Lenses

Eye problems can affect anyone of us, at one time or the other. Some defects of human eye are minor and can get treated on their own such as momentary sensitive eyes or watery eyes. These are generally the result of rising pollution. On the other hand, there are refractive issues that can be major. These are the defects of human eye that can last forever. Defects such as astigmatism, presbyopia, near- and far-sightedness. These become severe with time and result in partial or complete vision impairment if not addressed well on time.

As a practice, you must get regular eye check-ups done by an optometrist for any signs of vision problems. If routine testing indicates that your eyes have any refractive errors, your optometrist may suggest wearing corrective prescription eyeglasses or contact lenses. This is to improve your eyesight or undergo surgical correction.

Eye defects - Eye lenses

Different defects of human eye and how do they affect the choice of contact lenses/glasses:

1. Astigmatism

Astigmatism is a common human eye defect. It causes blurred vision due to an irregular shape of the cornea or an uneven curvature of the eye lens. Other symptoms of astigmatism include squinting, headaches, eye strain, and fatigue. 

Corrective glasses or contact lenses can help treat astigmatism. Usually, eyewear with cylindrical lenses (these lenses curve more in one direction than the other) is used to treat moderate to severe astigmatism. 1

Contacts can also be used to treat astigmatism by providing optimal on-eye stability. These are combined with ease of fit and vision acuity. 

Myopia (Near-sightedness) eye defects
Image source – Shutterstock

2. Hyperopia (Far-sightedness)

Hyperopia or Far-sightedness refers to the ability to clearly view objects at a far distance than those at a close range. 

Far-sightedness occurs when your cornea has too little curvature, or your eyeball is shorter than average (the measurement is done from front to back.) The smaller curvature reduces the distance between the retina and cornea. This causes incident light to converge behind the retina instead of on it.2

If you are moderately or severely hyperopic, you have the option to use eyeglasses, contact lenses or get surgery [LASIK or Photorefractive Keratectomy (PRK)]. Both contact lenses and glasses help correct far-sightedness. This is done by increasing the focusing power of your eye so that the light falling on your eyes converges on your retina. 

Eyewear with convex lenses (these lenses are thickest in the middle, similar to a magnifying glass) is used to improve sight in case of hyperopia. The numerical prescription for such glasses and contact lenses (in Dioptres) is marked with a Plus (+) sign. If you are not much keen on wearing glasses, you can choose from different types of contact lenses depending upon their comfort, breathability, and glare reduction properties.

Hyperopia (Far-sightedness)
Image source – Shutterstock

3. Myopia (Near-sightedness)

Myopia, also known as near-sightedness or short-sightedness, refers to the problems related with the eye’s focusing capability to look at distant objects. This happens because the eyeball is longer than average, as measured from front to back.

If you are near-sighted, the incident light converges too early inside the eye – focusing on a point in front of the retina, and not on it3. Both contact lenses and glasses correct myopia by diverging the incident light rays in the eye so that the eye’s focal point falls onto the retina. 

Near-sightedness is generally diagnosed during routine eye check-ups. If diagnosed, your optometrist may suggest possible corrective treatments. These methodologies may include prescription eyeglasses and contact lenses. The 

 optometrist may also suggest surgical vision correction through LASIK, (RK), , or photorefractive keratotomy (PRK), in more severe cases. Many individuals also opt for surgical visual correction themselves, under the care of an optometrist to achieve vision acuity. 

Eyewear with concave lenses (these lenses are thinnest in the centre) is used to correct myopia, and these lenses have numerical power description in dioptres (D) 4, denoted by the Minus (-) symbol

Astigmatism

4. Presbyopia

Presbyopia, commonly known as aging eyes, is an eye condition in which the lens of your eye may gradually lose its flexibility. Subsequently, it will become harder for you to focus clearly on objects placed close by, such as printed words in newspapers. On the other hand, your ability to see distant objects is usually not affected or remains the same as it was before Presbyopia

Presbyopia is inevitable with ageing. Thus, you cannot prevent it through dietary or lifestyle improvements. However, the condition is treatable with different types of contact lenses and glasses (such as bifocals, trifocals, progressives, multifocal contact lenses, single-vision reading glasses, and monovision therapy). 

Have impaired vision? Contact lenses got your back:

Different types of eye defects can hamper your vision if left untreated. Over the years, however, there has been tremendous improvement in eye care techniques and devices – meaning that you can quickly correct almost any visual impairment with contact lenses and eyeglasses. 

Soft contact lenses (both silicone hydrogel and hydrogel contact lenses) from leading brands such as Bausch + Lomb provide optimal vision correction These different types of contact lenses also help provide differential lens power across different meridians of the design to correct conditions such as astigmatism. In contrast, multifocal contact lenses (such as bifocal contact lenses) can help correct presbyopia. 

Sources: 1,2,3,4

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