The halo effect – when it occurs, what it signals

The halo effect is an aberration that involves seeing luminous halos around light sources.

It can occur in the following situations:

• As a harbinger of an eye disease: this happens, for example, during the development of cataracts, glaucoma or corneal cone. If the deterioration of visual acuity is accompanied precisely by symptoms such as the halo effect and blurring of the image, you should visit an ophthalmologist as soon as possible.

• As an additional symptom in such visual defects as hyperopia or astigmatism. If they are not corrected with eyeglasses or contact lenses, as a result of constant squinting and repeated attempts to catch optimal visual acuity, objects far away from the eye are not only seen as blurry, blurred, but such behavior also leads to the halo effect.

• As a temporary effect in the recovery process after laser eye surgery. Regardless of the surgical method, the patient must expect that for the first 24 hours after surgery, the glare or halo effect may also appear. A particularly intense halo effect appears after the LASIK procedure – It afflicts patients mainly at night, in which case it is recommended to wear glasses with anti-reflective lenses for driving.

• As a side effect of implanting certain types of artificial lenses. This is the case, for example, with refractive lenses, which use the phenomenon of refraction, which involves the refraction of light after it passes through an optical medium. Their significant disadvantages include precisely the increase in higher-order aberrations and undesirable photo-optical phenomena of the glare and halo types, which are especially aggravated in scotopic conditions (that is, at night). At the other extreme, as far as the halo effect is concerned, we have, for example, lenses from EVO Visian ICL (phakic lenses are made of a material with properties very similar to the natural lens of the eye), which guarantee a smaller halo effect due to fewer induced aberrations and a larger optical zone.

• As one of the most common post-operative inconveniences after corneal scar removal: excessive sensitivity to light and the formation of glows around light sources (halo effect) can last up to several months.

It is worth knowing that one of the tests during the diagnosis before laser vision correction is the measurement of the pupil width. It is performed because, as a standard, laser correction is performed on an area slightly larger than the pupil of the eye in the dark.

This ensures that after laser vision correction the eye will see equally well in all lighting conditions. Too small a surgical field would result in strong halo and glare effects and poor vision after dark and at night.