Hypermetropia, hyperopia or far-sightedness is a type of ametropia. The term ametropia means that due to abnormalities within the refractive structures of the eye or due to an abnormal size and/or shape of the eye, light rays from a distant object cannot be focused onto the part of the retina (the innermost, light-sensing layer of the eye) which forms the clearest image (the fovea centralis).
In hypermetropic or far-sighted individuals, if the crystalline lens is relaxed (I.e. there is no accommodation), light rays from a distant object are refracted in such a way that they are focused behind the retina. Thus individuals suffering from hypermetropia (or hyperopia) are able to properly visualise far objects but have trouble seeing near objects clearly. This phenomenon may occur due to:
- Decreased curvature of the refractive media of the eye (cornea or lens)
- Decreased axial length of the eyeball: This may cause the light rays to be focused behind the eyeball even if there are no abnormalities within the refractive media of the eye
- Decrease in the refractive index of the crystalline lens: This may occur due to opacification
- If the crystalline lens is displaced posteriorly, or is absent all together, the light will be focused behind the retina
Almost all newborn babies suffer from hyperopia because their eyes are underdeveloped. This refractive error typically corrects itself as the child grows older. However, if the baby has a different amount of untreated refractive error in either eye, then a serious condition called ‘amblyopia’ may develop. In this condition the child is only able to see from one eye because the brain is not used to interpreting signals from the other eye. It may also cause the child to develop a squint. This condition, however serious it may be, can easily be treated by an ophthalmologist if caught early. Hence, it is imperative that an eye doctor be consulted if any suspicions are present with regards to a baby’s vision.
Total refractive error
The total refractive error ailing a hyperopic individual consists of two components. These include:
- Latent Hypermetropia: This is the amount of refractive error that is generally not experienced by the individual because the normal convexity of their crystalline lens compensates for the abnormality without the need of accomodation.
- Manifest hypermetropia: This is the refractive error that actually ails the individual. It further consists of two components:
- Facultative hypermetropia: This term refers to the refractive error which may be compensated for by the changes in the shape of the crystalline lens (accommodative reflex).
- Absolute hypermetropia: This is the amount of refractive error which can not be fixed by the normal accommodative reflex of the eye. Absolute hypermetropia is the error which is fixed with the use of spectacles or contact lenses.
The main complaints of hyperopic individuals include:
- Blurring of near vision
- Sudden dimness
- Eye Strain (Asthenopic) symptoms are experienced due to exhaustion of the eye produced by sustenance of the accommodative reflex. These include:
- Watering of the eyes
- Tiredness of the eyes
- Photophobia (bright light hurts the eyes)
- Squinting of the eyes
Evaluation of disease:
To confirm the diagnosis, your doctor may ask you to read alphabets/signs placed at a certain distance. Your eyes may also be examined using different apparatus. An ultrasound test, or a test to chart the curvature of your cornea may also be ordered.
Treatment of hyperopia may be conservative or surgical.
- Conservative (optical) therapy options are preferred for individuals less than the age of 25. This is because after the age of 25, the eyeball stops growing and the refractive error stabilises. Conservative therapies include the use of:
- Spectacles which have biconvex lenses
- Contact lenses
- Surgical therapies: Your doctor is best equipped to decide whether or not surgery will correct your hyperopia. Surgical correction of hyperopia is done by performing surgery on the cornea or by replacing the crystalline lens.
Important points to know:
Cigarette smoking during pregnancy is linked to the development of hyperopia in the baby. As mentioned before, amblyopia is a serious complication of hyperopia in newborns that can be easily treated if diagnosed at an early age. Proper eye care and follow-up is essential to promote eye health.
Neil Charman, W., Plainis, S., Rozema, J., & Atchison, D. A. (2015). Hypermetropia or hyperopia?. Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists), 35(1), 2–7. https://doi.org/10.1111/opo.12168
Majumdar S, Tripathy K. Hyperopia. [Updated 2021 Jul 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560716
Schiefer, U., Kraus, C., Baumbach, P., Ungewiß, J., & Michels, R. (2016). Refractive errors. Deutsches Arzteblatt international, 113(41), 693–702. https://doi.org/10.3238/arztebl.2016.0693
Disclaimer: The information on this blog is intended to educate and inform and is not a substitute for medical advice, diagnosis or treatment. Prior to acting on the information provided on this blog, you should consult your doctor/healthcare professional.