The eye functions like a camera. Light rays enter the eye through the cornea (the clear window in front), pass through the pupil (the opening in the center of the iris), focused through the lens, and finally reaching the retina at the back of the eye. The retina is analogous to the film of a camera. When light rays land on the retina, they form an upside-down image. The retina converts the image into impulses that travel through the optic nerves to the brain, converting them into upright visual images.
Vision is clear only if the cornea and lens correctly bend or "refract" the light rays and focus them at the point on the retina known as the fovea. The cornea's focusing power is matched to the eye's length in the normal eye. Blurry vision may be due to what is called a "refractive error" - the failure of the cornea and lens to focus light properly. Prescription eye glasses, contact lenses, and refractive surgery correct or improve refractive errors by focusing light rays closer to or directly onto the retina.
Some common eye conditions include:
Myopia, or short-sightedness, is a refractive error where distant objects appear blur but near objects can be seen clearly. Myopia arises when the cornea is overly curved (focusing power is too high) or the eyeball is too long. This causes images of distant objects to be focused in front of the retina instead of on the retina. A blurred image falls on the retina as the light rays spread apart after the focal point. Singapore has one of the highest rates of myopia in the world with an estimated 28 per cent of Primary 1 students, 65 per cent of Primary 6 students, and 80 per cent of young adults being myopic. To learn more about myopia in children and their treatment options, please click here. |
What are the treatment options for Myopia (Short-sightedness)? Myopia can be corrected with corrective lenses such as glasses and contact lenses, or refractive surgery (LASIK). Contact Lenses Contact lenses provide a safe and effective way to correct vision as they allow light to be focused more precisely on the retina. Refractive Surgery (LASIK) Refractive surgery, such as LASIK, is a common surgical procedure that uses laser to correct myopia. |
Astigmatism is a refractive error that occurs when the cornea of your eye is curved more in one direction or has a non-spherical shape (like a rugby ball or the back of a spoon). It does not bring the light rays to focus at a single point. Instead, it focuses images over a spread of points producing a blurred image. Astigmatism often occurs in combination with near-sightedness or far-sightedness. |
What are the signs & symptoms of Astigmatism? Signs and symptoms for astigmatism include blurred and distorted vision, eye strains and headaches. |
What are the treatment options for Astigmatism? Astigmatism can be corrected with corrective lenses such as glasses and contact lenses, or refractive surgery (LASIK). Contact Lenses Contact lenses provide a safe and effective way to correct vision as they allow light to be focused more precisely on the retina. Refractive Surgery (LASIK) Refractive surgery, such as LASIK, is a common surgical procedure that uses laser to correct astigmatism. |
Hyperopia, or far-sightedness, is a refractive error where distant objects can be seen clearly but near objects appear blur. Hyperopia arises when the cornea of the eye is not curved enough (focusing power too low) or the eyeball is too short. This combination of factors results in the focal point to fall behind the retina. A blurred image is seen as light rays have not yet been brought into focus when they reach the retina. |
What are the treatment options for Hyperopia (Far-sightedness)? Hyperopia can be corrected with corrective lenses such as glasses and contact lenses, or refractive surgery (LASIK). Contact Lenses Contact lenses provide a safe and effective way to correct vision as they allow light to be focused more precisely on the retina. Refractive Surgery (LASIK) Refractive surgery, such as LASIK, is a common surgical procedure that uses laser to correct hyperopia. |
Presbyopia, known commonly as old-sightedness, is a refractive error caused by the eye’s natural ageing process resulting in an inability to focus on near objects. As the normal eye ages, the lens loses its elasticity and ability to change its shape. Focusing for near tasks, including reading, will then require the help of reading glasses. This usually begins to affect most people from the age of 40 onwards. |
What are the treatment options for Presbyopia (Old-sightedness)? Presbyopia can be corrected with bifocal contact lenses and glasses, or refractive surgery (LASIK, PRK or PRESBYOND). Contact Lenses Contact lenses provide a safe and effective way to correct vision as they allow light to be focused more precisely on the retina. Refractive Surgery Presbyopia can also be treated with either LASIK or PRK. One eye can be corrected to see far and the other eye corrected to see near. This is also known as monovision. By doing this, the person can then see both far and near without the need for glasses or contact lenses. Confusion does not occur and the brain easily adapts to this new vision after one to two weeks. There is also no problem with activities such as driving or playing golf. The blending of vision between the two eyes can be further enhanced using aspherical treatment to increase the depth of focus of both eyes. |
Low vision refers to visual impairment that cannot be corrected with standard glasses, contact lenses, medical treatment and surgery. A person with low vision has severely reduced visual acuity, contrast sensitivity and/or significantly obstructed field of view. Low vision may affect a person's daily living activities such as recognising faces, reading small prints and large signs, difficulty in recognising obstacles and reduced independent mobility. The common causes of low vision are age-related macular degeneration, diabetic retinopathy, glaucoma, neurological conditions and trauma. |
What are the treatment options for Low Vision? Persons with low vision usually retain some usable vision. In our institutions, there is a Low Vision Enabling Programme that comprises a multidisciplinary team of optometrist and occupational therapist who specialises in low vision rehabilitation. The team works closely with the patient and family to help the patient regain function lost by visual impairment. This involves a comprehensive approach in addressing visual and functional issues that results in problems with reading, safety, daily living activities, community participation and psychological adjustment to vision loss. Low vision rehabilitation aims to reduce the functional impediments imposed by vision loss. It begins with a low vision consultation, which involves optometric low vision evaluation and occupational therapy assessment. This may be followed by prescription and dispensing of low vision optical devices such as magnifiers, telescopes, assistive technology and sensorial adaptive devices as appropriate. In addition, visual skills trainings and adaptive therapies may be provided to maximise function, safety and independence of the individual with low vision. The comprehensive rehabilitation service will be conducted at home and/or in the clinic. |
Click here to access our Find A Doctor directory for a list of doctors treating this condition across our NUHS institutions.
