Following treatment for mild to moderate myopia (up to -5.0 dioptres) over 95% of patients will not require spectacles or lenses for most everyday activities, the remaining 5% may require them for visually demanding tasks such as driving.
For higher levels of myopia (greater than -5.0) it is less likely that patients will be able to see perfectly unaided. Unaided vision will however, be greatly improved and spectacles considerably thinner. Above -5.0 dioptres, 90% can expect 6/12 or better unaided vision.
It should be explained that 6/12 is approximately the visual acuity required to drive a car, play most sports and perform many day to day tasks. 6/6 vision is “perfect” or “normal” vision (which is probably the vision that you presently obtain with spectacles).
The degree of myopia can fluctuate a little for up to six months after laser treatment but thereafter the effects are usually stable. Although it is established that the various treatment options can reduce the degree of short-sight, the exact amount in each case cannot be guaranteed.
The results of excimer laser treatments performed at Sunderland Eye Infirmary are continuously audited.
The response of astigmatism to excimer laser is more variable than myopia alone and if you simply have myopia your outcome may be slightly more favourable than the results above.
Patients with low degrees of hypermetropia (up to +3.0 dioptres) 95% can expect to achieve 6/12 or better unaided vision following treatment.
Higher degrees of hypermetropia (over +3.0 to +6.0 dioptres) are more difficult to correct but patients can expect an 85% chance of 6/12 or better unaided vision with treatment.
For those with extreme long-sight of over +6.0 dioptres results are much less predictable and outcomes would need to be discussed at the assessment consultation.
The visual outcome following treatment for astigmatism will depend partly on the degree of astigmatism and the underlying amount of short or long-sight, together with the type of treatment performed.
On average, patients can expect to have a reduction of 66-75% in the amount of astigmatism with treatment. Some may however, do better or worse.
If the residual astigmatism after treatment is less than 1.0 dioptre and there is no significant short or long sight then the unaided vision should be good.
Higher degrees of residual astigmatism may mean that glasses or contact lenses are required to achieve the best vision.
All forms of surgery carry some degree of risk and complications are possible
Refractive surgery enjoys a high safety record. It is however an elective procedure and there are certain potential complications and risks that you should be aware of before considering treatment.
The surgeon is able to predict, fairly accurately, your expected result but as each person has a different prescription and healing rate it is not possible to give an absolute guarantee.
Short term side effects
(which should not permanently affect vision)
Glare/light sensitivity: post treatment sensitivity to sunlight and glare usually settles within a few days.
Fluctuations in vision: Fluctuations in vision are a normal part of the healing process. These usually last for less than one month.
Difference in refractive error between eyes: If only one eye is treated at a time it does mean that for a period of time (depending on the timing of the treatment of the second eye), the untreated eye will be short (or long) sighted and the treated eye may be normally sighted. If you have a high prescription you may not be able to wear glasses that correct the vision in both eyes during this time.
Dry eyes: A few patients may experience some discomfort due to dry eyes after laser. This may require the use of lubricating treatment. Symptoms will normally resolve within six months.
(which should not affect best corrected vision)
Overcorrection or undercorrection: as all patients’ eyes differ in the rate and method of healing, treatment might not result in the expected correction. Over 90% of patients with lower levels of myopia might achieve 6/12 without glasses. Some, however, will be a little over or under corrected and will require glasses or contact lenses to obtain best vision. There can be no guarantee of the final accuracy of treatment. In general, all patients obtain a significant improvement with unaided vision and if glasses are still required these are usually much thinner than before.
Reading glasses: Presbyopia, the term used to describe the need for reading glasses usually occurs in middle age as a result of the eye’s natural ageing. Most people require reading glasses in mid to late forties, they are often not required by short-sighted people of this age. A person with normal vision when younger will require reading glasses from the age of about 45 years. If myopia is corrected, the patient will effectively become “normal sighted” and though glasses may not be required for everyday tasks, when the person reaches middle age, reading glasses may be required for near work.
Decrease in Best-Corrected Visual Acuity: It is possible that surgery could affect your best corrected vision (the level of vision you can currently achieve with your glasses or contact lenses). If so, your best vision, with glasses, may not be as good after surgery as it was before.
Starburst/Night Haloes: Following treatment individuals may experience halos, starbursts or similar effects around street lights and car lights at night. This tends to get less and less with time, but may not disappear completely. It can make driving at night difficult for some people.
You will have the opportunity to discuss any of these risks in more detail at your consultation.