Risks & Side Effects

Risks

At Perfect Vision Laser Correction, we won’t take unnecessary risks with your eyesight. Our surgeons will not accept a patient for any eye treatment unless confident they can improve their vision. Perfect vision can be achieved in many, but not all of our patients.

The final outcome of laser procedures is very dependent on the individual healing process of each patient and this may result in under or overcorrection. Although a final visual outcome can be suggested from studies of large numbers of patients, and therefore the visual results can be considered reasonably predictable, the final amount of correction cannot be absolutely guaranteed.

Use the information below to find out about certain side effects that can occur, and how they can be treated. Fortunately, most side effects and complications resolve within three months of surgery and they do not result in long-term vision problems.

Dry Eye

Cause

A temporary reduction in neural communication between the cornea and Lacrimal gland, due to loss of corneal nerves when forming the flap. The exact mechanism of control is unknown, but viable corneal innervation is thought to be instrumental in the regulation of baseline tear gland output.

Incidence

Making a LASIK flap severs corneal nerves. Some drying effect is therefore inevitable in all patients, but it is only symptomatic in 50%. CSA treatment preserves more of the corneal nerves, thereby resulting in 20% of patients reporting dry eye symptoms.

Management

Patients are routinely given tear supplements for 4 weeks post treatment; those who remain symptomatic after this time (5%) are managed with gel tear substitutes and/or punctal occlusion.

Glare

Cause

The corneal wound healing response to the treatment process involves a build-up of haze within the cornea. This is an effect of the biochemistry of the corneal reaction to the laser treatment. This haze causes forward light scatter, which results in extraneous light causing loss of contrast of the retinal image.

Incidence

All patients experience photophobia (light sensitivity) in the immediate hours following the treatment. iLasik patients see an improvement within 24 hours and the phenomenon dissipates within 7 days. CSA patients can see more persistent haze, due to the necessity to replenish those epithelial cells, which have died in the formation of the intra-epithelial flap. As in the past with PRK patients, for whom haze was a significant complication, all residual haze improves with time to the point where it is not symptomatic.

Management

Patients are advised to attend for their treatment appointment with dark glasses to give comfort during the first 3-5 hours. Patients are also advised not to use their eyes excessively, avoid brightly lit environments, and not to watch television or use computer equipment immediately post-treatment.

Haloes/Starbursts

Cause

Altering the shape of the cornea with Excimer laser treatment results in a temporary increase in the higher order aberration of the eye. These have the effect of creating haloes around lights (induced spherical aberration), or distorting bright points of light into starburst effects (coma and trefoil aberration). These are more evident in low ambient illumination, hence the fact that they are only reported at night. 

Incidence

Temporary night vision difficulties of this type are reported in the immediate post-treatment period by most individuals. Persistent night vision difficulties occur in less than 5%.

Management

The healing process takes time to complete and the aberration increase is evident for approximately 3 months. Individuals who are particularly susceptible can be identified by pre-operative aberrometry (now routinely carried out on all Perfect Vision Laser Correction patients). These individuals are advised to opt for Wavefront-guided laser treatment, which is specifically customised to reduce total post-operative aberrations.

Night Vision Problems

Cause

The cornea’s healing process causes a loss of contrast sensitivity, which can result in poorer quality vision in low illumination. Very similar to haloes/starbursts and haze, in that these difficulties are related to the healing processes and are temporary in nature.  

Incidence

Loss of low contrast vision is a normal consequence of treatment, but is symptomatic in only a minority of patients.

Management

Once the healing process is complete, the contrast sensitivity shows a return to normal levels without intervention.

Epithelial in-growth 

Cause

In making the flap, but more usually in lifting a flap for a second treatment, some corneal epithelial cells can become trapped under the flap. In most cases they will be reabsorbed but, rarely, cytokines (chemicals promoting cell replication) will reach the cells and encourage them to grow through the flap tissue, with the damaging result of tissue loss ("corneal melting").

Incidence

.9% of primary treatments, 1.7% of re-treatments.

Management

The flap must be lifted and carefully cleaned to remove these cells.