Around four per cent of all newborn children have a squint. In about 50 per cent of cases, this can be corrected with appropriate glasses, however the other half require treatment for their squint and in some cases even squint surgery. To mark World Sight Day tomorrow, Thursday 9th October 2014, and Sight Week (8th - 15th October), Guido Dorner from the University Department of Ophthalmology and Optometry at the MedUni Vienna / Vienna General Hospital is pointing out that the surgical treatment of strabismus (squinting) can be carried out at any age - including with minimally invasive methods and with maximum care even during childhood.
"Essentially, almost all children are born long-sighted, at plus 1.5 Dioptres", explains Guido Dorner, Head of the Paediatric Ophthalmology and Squint Therapy Outpatient Clinic at the MedUni Vienna / Vienna General Hospital's University Department of Ophthalmology and Optometry. "This long-sightedness resolves in most children as time passes and their eyes grow longer. If their long-sightedness is more pronounced, however, from around plus 3.5 Dioptres, for example, then this is the most significant risk factor for the development of squints. Even in the first year of life, the prescription of glasses is unavoidable in such cases. In the second group of children, the eye positioning reflexes are too weak at birth. Strabismus generally cases amblyopia in one eye. This must be diagnosed in the first or second year of life and treated with consistent eye occlusion, known as the "pirate's plaster" over one eye, otherwise the lazy eye will remain for life."
Early examination with the paediatric ophthalmologist
Until the start of the 1980s, it was normal not to carry out squint surgery before age of five or six, especially in view of the risks of anaesthesia in children. Since then, however, paediatric anaesthesia alone has come a long way. Additionally, in 1981, the American-Swedish scientists David Hunter Hubel and Torsten Nild Wiesel were awarded the Nobel Prize for Physiology and Medicine for discovering that binocular vision and information processing in the visual perception system is essentially developed during the first year of life.
Says Dorner: "As a result, early examination by a paediatric ophthalmologist is advisable, especially if there is a family history of squinting, if there are any other indicators of squinting or in cases of premature birth." In younger children, correct treatment can ensure full vision with both eyes, promotes the development of spatial vision and guarantees long-term success.
Why do people squint anyway?
Each eye is moved by six external eye muscles. If there is a marked imbalance between the muscle tension and/or if the brain's ability to merge information from the two images that the eyes "send" to the brain is inadequate, a squint develops. During squint surgery, overlaying or folding of the eye muscles restores a balance in the muscle tension - without the need for any intervention inside the eye itself. The tendon attachment points are located underneath the conjunctiva and are accessible via a small, minimally invasive conjunctival incision in the orbit. A squint operation takes around 30 - 60 minutes and is carried out as a day case at the MedUni Vienna / Vienna General Hospital. "We were one of the first facilities in Austria to offer day-case surgery for this condition," says Dorner.
The squint outpatient clinic in Vienna is regarded as highly innovative, offering high-end services that are renowned all over the world. Says Dorner: "State-of-the art diagnostic equipment (such as RetCam, portable OCT) and treatment facilities are available, the team has four ophthalmology specialists, two assistants and six orthoptists, as well as qualified practitioners with specialist knowledge, especially of dealing with very young children." Each year, more than 3,500 outpatient appointments and over 280 squint operations are carried out at the MedUni Vienna / Vienna General Hospital.
Squint treatment is also very important in adults, for example in the case of phoria (marked malpositioning of the eyes, for instance when tired) or if paralytic squints occur with double vision due to cranial nerve deficits, which can often be the consequence of poorly controlled diabetes, hypertension or arteriosclerosis.