Eye conditions are affected by age, heredity and lifestyle, and may lead to a number of short-term symptoms or long-term complications. These conditions can often be treated by daily eye care, corrective products or permanent solutions such as surgery. If you are concerned about any of the following conditions, visit a professional using our Find a Practice search.
(short-sightedness or nearsightedness)
Myopia occurs when the physical length of the eye is greater than the optical length.1 Myopia causes images to come into focus in front of the retina, rather than on the retina.2 As a result, a person sees closer objects clearly, but cannot focus correctly on distant objects.
Although myopia is largely caused by genetic factors, experts have also cited working up close, psychological stress and diet as possible causes of the condition.3
Symptoms of myopia include blurred vision of distant objects, squinting and headaches.
(hypermetropia, farsightedness or long-sightedness)
Hyperopia occurs when the physical length of the eye is less than the optical length.4 Hyperopia causes images to come into focus behind the retina, rather than on the retina, making nearer objects appear blurred.
Hyperopia is caused by genetic factors, and often newborns are hyperopic until their eye begins to grow. Since slow eyeball growth is also a cause of hyperopia, the condition usually does not disappear with age.5
Symptoms of hyperopia include blurred vision of close objects, eyestrain, squinting and headaches.6
Astigmatism is an irregularity in the curvature of the cornea or lens. This causes different planes of light (whether horizontal, vertical or diagonal) to be focused differently.7
Signs of astigmatism include certain lines being seen in better focus than others. This can differ in each eye. Astigmatism often occurs with myopia or hyperopia.7
Astigmatism can lead to headaches, eye strain and blurred vision at all distances.
Presbyopia is the loss of ability to see objects that are near.9 It generally begins to occur when people reach their early 40s10 and the eye’s lens loses its flexibility as a part of its natural ageing process.9
People with presbyopia have difficulty performing close-up work and may experience headaches, eyestrain or fatigue.11
Keratoconus is when the cornea gradually thins slightly, changes shape and becomes distorted. It usually begins to affect people between the ages of 15 and 25 and may require corneal transplantation in severe cases.12
Symptoms of keratoconus include moderate-to-severe distortion of vision (irregular astigmatism) or blurred vision (pseudo-myopia).13
Dry eye syndrome
Dry eye syndrome is a chronic lack of lubrication and moisture in the eye. This is caused either by the eye not producing enough tears or being unable to stop the tears from evaporating.14
Symptoms of dry eyes include irritation, itchiness, scratching, burning and inflammation of the front tissues of the eye.14 This can be corrected by using eye drops, ointments or tear-duct plugs to stimulate moisture in the eye.
Computer vision syndrome
Computer vision syndrome describes a group of vision-related problems that result from prolonged computer use.15
Symptoms of computer vision syndrome include eyestrain, headaches, dry or irritated eyes and blurred vision.1 Many of these symptoms are temporary, but some people may experience prolonged or exacerbated symptoms over time.15
Computer vision syndrome should be managed by reducing glare in the workplace, positioning a computer so the user looks down at the screen and taking regular breaks from the computer.
Blepharitis is the inflammation of the edges of the eyelids, possibly with scales, crusts, ulcers or inflamed oil glands.17 Blepharitis may affect the outside of the eyelid (anterior blepharitis) or the inner eyelid (posterior blepharitis).18
Causes of blepharitis include infection, dermatitis or acne in the eyelid area, which may lead to itching, burning, redness, sensitivity and swelling. 17
Keeping the eyes clean by regularly and gently scrubbing the edge of the eyelids each day will reduce infection while warm compresses may ease itching and burning.17
Meibomian gland dysfunction
Meibomian gland dysfunction occurs when the meibomian glands, responsible for producing the lipid fluid that prevents tear evaporation,19 release less lipid fluid than normal or lipid fluid with abnormal composition.20
This results in increased tear evaporation and loss of lubrication in the eye,14 causing the eyes to feel dry and irritable. Other symptoms may include itching, burning or the secretion of a yellowish, waxy substance from the glands.20
- Griggs, P. 2008, Nearsightedness, U.S. National Library of Medicine. Accessed 30 January 2009, available <http://www.nlm.nih.gov/medlineplus/ency/article/001023.htm>.
- Rehm, D. 1981, The Myopia Myth, International Myopia Prevention Association, PA, U.S.A., p. 3.
- Committee on Vision, Commission on Behavioural and Social Sciences and Education, National Research Council 1989, Myopia: Prevalence and Progression, <http://www.nap.edu/openbook.php?record_id=1420&page=91>.
- Griggs, P. 2008, Farsightedness, U.S. National Library of Medicine. Accessed 30 January 2009, available <http://www.nlm.nih.gov/medlineplus/ency/article/001020.htm>.
- Singh, D. 1998, Hyperopia, eMedicine. Accessed 4th February 2009, available <http://emedicine.medscape.com/article/1221201-overview>.
- Scheiman, M. 2002, Understanding and Managing Vision Deficits, SLACK Incorporated, p. 31.
- Colby, K. 2003, Symptoms and Diagnosis of Eye Disorders in The Merck Manual of Medical Information, 2nd Edition, West Point, PA, USA, p. 1278-1286.
- Lee, J. & Bailey, G. 2008, Astigmatism, Access Media Group. Accessed 4th February 2009, available <http://www.allaboutvision.com/conditions/astigmatism.htm>.
- Grayson, C. 2004, Presbyopia, MedicineNet. Accessed 4th February 2009, available, <http://www.medicinenet.com/presbyopia/article.htm>.
- Roat, M. 2003, Refractive Disorders in The Merck Manual of Medical Information, 2nd Edition, West Point, PA, USA, p. 1286-1290.
- Lee, J. & Bailey, G. 2007, Presbyopia, Access Media Group. Accessed 4th February 2009, available <http://www.allaboutvision.com/conditions/presbyopia.htm>.
- Roat, M. 2003, Corneal Disorders in The Merck Manual of Medical Information, 2nd Edition, West Point, PA, USA, p. 1299-1302.
- NIH 2008, US Department of Heath and Human services. Accessed 4th February 2009, available <http://www.nei.nih.gov/health/cornealdisease/#h>.
- Lee, J. & Bailey, G. 2007, Dry Eye Syndrome, Access Media Group. Accessed 4th February 2009, available <http://www.allaboutvision.com/conditions/dryeye.htm>.
- AOA 2008, Computer Vision Syndrome, American Optometric Association. Accessed 4th February 2009, available <http://www.aoa.org/x5253.xml>.
- Anshel, J. 2005, Visual Ergonomics Handbook, CRC Press, California, USA.
- Friedlaender, M. 2003, Eyelid and Tear Gland Disorders, in The Merck Manual of Medical Information, 2nd Edition, West Point, PA, USA, p. 1292-1295.
- White, G. 2009, Blepharitis, Access Media Group. Accessed 4th February 2009, available <http://www.allaboutvision.com/conditions/blepharitis.htm>.
- Goto, E., Monden, Y., Takano, Y., Mori, A., Shimmura, S., Shimazaki, J. & Tsubota, K. 2002, Treatment of non-inflamed obstructive meibomian gland dysfunction by an infrared warm compression device, British Journal of Opthomology, Vol. 86, No. 12, p. 1403-1407. Available <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1771385>.
- Garrity, J. 2007, Blepharitis, The Merck Manual Online Medical Library. Accessed 4th February 2009, available <http://www.merck.com/mmpe/sec09/ch100/ch100b.html>.