What can go Wrong? Early Postoperative Complications A subconjunctival hemorrhage is a common and minor post-Lasik complication. The incidence of refractive surgery patients having unresolved complications six months after surgery has been estimated from 3% to 6%. The following are some of the more frequently reported complications of Lasik: * Dry eyes * Overcorrection or undercorrection * Visual acuity fluctuation * Halos or starbursts around light sources at night * Light sensitivity * Ghosts or double vision * Wrinkles in flap (striae) * Decentered ablation * Debris or growth under flap * Thin or buttonhole flap * Induced astigmatism * Epithelium erosion * Posterior vitreous detachment * Macular hole Late Postoperative Complications Glare is another commonly reportedly complication of those who have had Lasik . Halos or starbursts around bright lights at night are caused by the irregularity between the lasered part and the untouched part. It is not practical to perform the surgery so that it covers the width of the pupil at full dilation at night, and the pupil may expand so that light passes through the edge of the flap into the pupil. In daytime, the pupil is smaller than the edge. Newer equipment is available to properly treat those with large pupils, and responsible physicians will check for them during examination. Safety and Efficacy The reported figures for safety and efficacy are open to interpretation. In 2003, the Medical Defence Union (MDU), the largest insurer for doctors in the United Kingdom, reported a 166% increase in claims involving laser eye surgery; however, the MDU averred that these claims resulted primarily from patients' “unrealistic expectations” of Lasik rather than “faulty surgery”. A 2003 study reported in the medical journal Ophthalmology found that nearly 18% of treated patients and 12% of treated eyes needed retreatment. The authors concluded that “higher initial corrections, astigmatism, and older age are risk factors for Lasik retreatment.” In 2004, the British National Health Service's National Institute for Health and Clinical Excellence (NICE) considered a systematic review of four randomized controlled trials before issuing guidance for the use of Lasik within the NHS. Regarding the procedure's efficacy, NICE reported, "Current evidence on Lasik for the treatment of refractive errors suggests that it is effective in selected patients with mild or moderate short-sightedness" but that "evidence is weaker for its effectiveness in severe short-sightedness and long- sightedness." Regarding the procedure's safety, NICE reported that "there are concerns about the procedure's safety in the long term and current evidence does not appear adequate to support its use within the NHS without special arrangements for consent and for audit or research." Leading refractive surgeons in the United Kingdom and United States, including at least one author of a study cited in the report, believe NICE relied on information that is severely dated and weakly researched. Satisfaction Various surveys have been performed to determine patient satisfaction with Lasik. According to a 2005 survey, 92.2% of patients reported that they were satisfied or very satisfied with their surgery.