* Longsightedness (hyperopia): one clinic offering treatment for this with LASIK and LASEK says “treatment is still considered experimental by many ophthalmic surgeons”. The clinic offers treatment only “to those who are alerted to the risks and have moderate expectations” (J Cataract Refract Surg, 2003; 29: 912-7). One study showed that, while the procedure was deemed “safe”, it corrected low-to-moderate hyperopia to target levels in only 50 per cent of eyes treated (J Refract Surg, 2001; 17: 670-5).

* Age-related macular degeneration (AMD): the most common cause of blindness in middle and old age. The ‘wet’ form of the condition (which is far less common than the ‘dry’ form) can sometimes be treated with laser therapy. However, it cannot reverse any damage caused by AMD, though it may prevent further loss of vision.

* Diabetic retinopathy: damaged and abnormal blood vessels caused by diabetes. Laser photocoagulation uses a laser to seal off leaking blood vessels and to retard the growth of abnormal vessels. Retinal detachment may be prevented if the laser is used to seal the retina to the eye.

* Glaucoma: increased pressure in the eye damages the optic nerve. Laser surgery can be used to remove tissue from different parts of the eye to reduce the pressure.