Hyperopia Causes/Hyperopia also known as Farsightedness, is an eye condition that causes blurry near vision. People who are farsighted have more trouble seeing things that are close up (such as when reading or using a computer) than things that are far away (such as when driving).For normal vision, light passes through the clear cornea at the front of the eye and is focused by the lens onto the surface of the retina, which is the lining of the back of the eye that contains light-sensing cells. Some people who are farsighted have eyeballs that are too short from front to back. Others have a cornea or lens that is abnormally shaped.
Far-sightedness, also known as hyperopia, is a condition of the eye in which light is focused behind, instead of on, the retina.[rx] This results in close objects appearing blurry, while far objects may appear normal.[rx] As the condition worsens, objects at all distances may be blurry.[rx] Other symptoms may include headaches and eye strain.[rx] People may also experience accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus.[rx]
Types of Hyperopia
Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye’s accommodative status. There are three clinical categories of hyperopia.[rx]
- Simple hyperopia – Occurs naturally due to biological diversity.
- Pathological hyperopia – Caused by disease, trauma, or abnormal development.
- Functional hyperopia – Caused by paralysis that interferes eye’s ability to accommodate.
There are also three categories severity
- Low – Refractive error less than or equal to +2.00 diopters (D).
- Moderate – Refractive error greater than +2.00 D up to +5.00 D.
- High – Refractive error greater than +5.00 D.
Other common types of refractive errors are near-sightedness, astigmatism, and presbyopia.[rx]
Causes of Hyperopia
As hyperopia is the result of the visual image being focused behind the retina, it has two main causes
Farsightedness develops when the cornea and lens focus light behind the retina (back of the eye where images are formed) instead of on it. This problem with focusing can result from:
- An eyeball that is too short (from front to back)
- A flat shaped cornea (clear layer covering the front of the eye) or lens (clear disc that changes shape as it focuses)
- The lens becomes less flexible after about age 40 because of changes in its proteins.
- Muscles around the lens that help it change shape to focus may lose elasticity.
These age-related changes make it more difficult for your eyes to focus on close objects. You may notice that you need to hold reading material farther away to be able to see clearly enough to read.
- Low converging power of eye lens because of weak action of ciliary muscles
- Abnormal shape of the cornea
- Far-sightedness is often present from birth, but children have a very flexible eye lens, which helps to compensate.[rx]
- In rare instances hyperopia can be due to diabetes, and problems with the blood vessels in the retina.[rx]
Symptoms of Hyperopia
The signs and symptoms of far-sightedness are
- Blurry vision,
- Headaches, and
- Eye strain.
- Aching eyes and eyestrain
- Blurred vision, especially at night
- Difficulty reading small print without holding reading material at arm’s length
- Difficulty seeing objects up close
- Fatigue or headache after performing tasks that require close focus, such as reading or sewing
Farsightedness and presbyopia have different causes:
- Farsightedness occurs because the eye is too short and attempts to focus the image behind the retina (back of the eye). It usually is present at birth or develops in early childhood.
- Presbyopia occurs because the lens becomes more rigid with age, making it di
- Difficulty seeing with both eyes (binocular vision) may occur, as well as difficulty with depth perception.[rx]
- Squinting
- Blurry vision, especially for close objects
- Nearby objects may appear blurry
- You need to squint to see clearly
- You have eyestrain, including burning eyes, and aching in or around the eyes
- You experience general eye discomfort or a headache after a prolonged interval of conducting close tasks, such as reading, writing, computer work or drawing
Diagnosis of Hyperopia
You may have several of the following tests during the exam:
- Refraction test – Your optometrist determines your prescription for glasses, soft contact lenses or hard contact lenses with a phoropter, a device with lenses of different strengths.
- Retinal exam – The optometrist uses special eye drops to dilate your pupils, then examines the inside of your eye with a lighted instrument called an ophthalmoscope.
- Tonometry test – Our eye specialists measure pressure inside the eye using either a microscope and high-intensity light or an instrument that carefully touches the surface of the eye. High pressure can indicate glaucoma.
- Vision acuity test – This test uses an eye chart to assess your vision sharpness.
Several methods can be used for genetic testing
- Molecular genetic tests (or gene tests) study single genes or short lengths of DNA to identify variations or mutations that lead to a genetic disorder.
- Chromosomal genetic tests analyze whole chromosomes or long lengths of DNA to see if there are large genetic changes, such as an extra copy of a chromosome, that cause a genetic condition.
- Biochemical genetic tests study the amount or activity level of proteins; abnormalities in either can indicate changes to the DNA that result in a genetic disorder.
The American Academy of Ophthalmology (AAO) recommends the following intervals for eye exams
- Before age 3 – Vision screening during regular pediatric exams
- Age 3 to 19 – Vision screening every one to two years
- Age 20 to 39 – Complete eye exam to evaluate vision and check for eye diseases at least once by age 29 and at least twice by age 39
- Age 40 to 64
- Baseline screening for eye diseases at age 40, after which your eye specialist can recommend follow-up intervals.
- Vision testing each year for people who wear glasses or contact lenses
- Vision testing every two to four years for people with no vision or eye conditions
- Age 65 and over – Complete eye exam every one to two years to check for eye diseases and evaluate vision sharpness.
Treatment of Hyperopia
Your prescription will often contain three numbers for each of your eyes. These are:
- Cyl (cylinder) – this number will show whether or not you have astigmatism (a common eye condition where your lens or cornea isn’t perfectly curved – this can cause distorted or blurred vision) in either of your eyes
- Axis – describes the angle of astigmatism detailed above – if you have one
- Sph (sphere) – a negative number indicates you’re shortsighted, while a positive number will show you’re long sighted (have hyperopia)
Corrective lenses
The simplest form of treatment for far-sightedness is the use of corrective lenses, eyeglasses or contact lenses.[rx][rx] Eyeglasses used to correct far-sightedness have convex lenses.
- Glasses – can be an easy way to improve vision. Prescription glasses can fix refractive errors by altering the angle light rays enter the eye. Depending on your style and budget, there is an enormous selection of frames and eyeglass lenses to choose from.
- Contact lenses – work under the same principles as glasses. Contact lenses differ in materials (hard and soft) and duration of use (daily disposables or extended wear). It is important to understand that contact lenses are not without risks.
- Intraocular lens exchange – is another option that a doctor may recommend to correct hyperopia in certain patients. This is a surgical procedure in which an artificial lens is implanted in place of the natural lens. Intraocular lens exchange is a common procedure for patients suffering from cataracts, while refractive or clear lens exchange refers to patients without cataract. Your doctor can recommend this if it is an option for you as well as which IOL is right for you and your refractive error. Like all surgeries though, it is not without risks.
- Phakic intraocular lens (PIOL) – is an artificial lens, which is implanted in addition to the existing natural lens, and is used in refractive surgery to change the eye’s optical power. Like all surgeries though, it is not without risks.
Bifocal contact lenses
- Rigid gas permeable (RGP) lenses, the latest generation of hard contact lenses
- Soft lenses
- Hybrid lenses, which have an RGP center surrounded by a soft lens outer ring
Eyeglasses
- Bifocal with the top portion of the lens for far vision and the bottom portion for near
- Progressives, which are similar to bifocals but the lens sections are blended together rather than having a distinct separation between them
- Reading glasses to correct the near vision and help the person read and do other close tasks
Surgery
There are also surgical treatments for far-sightedness
- Photorefractive keratectomy (PRK) – Removal of a minimal amount of the corneal surface[rx][rx]
- Laser assisted in situ keratomileusis (LASIK) – Laser eye surgery to reshape the cornea, so that glasses or contact lenses are no longer needed.[rx][rx] It is another option to treat hyperopia. LASIK and PRK/LASEK both treat refractive errors. At this time, SMILE cannot treat hyperopia. Like all surgeries though, they are not without risks.
- Refractive lens exchange (RLE) – A variation of cataract surgery where the natural crystalline lens is replaced with an artificial intraocular lens; the difference is the existence of abnormal ocular anatomy which causes a high refractive error.[rx]
- Laser epithelial keratomileusis (LASEK) – Resembles PRK, but uses alcohol to loosen the corneal surface.[rx]
References
