After laser eye treatment, many patients ask themselves the question: Do I see colors differently? In fact, some people report a new visual experience in which colors are perceived more intensely and clearly. Thanks to the precise correction of vision defects such as short-sightedness or long-sightedness, the overall quality of vision can improve significantly – and this often also applies to colors, which previously appeared less vivid due to blurred vision. But how exactly does color vision change? And are there also possible temporary limitations? In this blog post, we shed light on why color perception can improve after laser eye surgery, what temporary effects such as halos and glare occur and what science has to say about this.

Influence of laser eye surgery on color perception: myth or reality for patients?

It is repeatedly claimed that laser eye surgery can significantly and permanently change color vision. But what is the truth of this claim?

How does color perception work?

Color perception is created by the interaction of light, the retina in the eye and the brain. There are special cells in the retina, known as cones, which react to different wavelengths of light. There are three types of cones, each of which is specialized for a specific color:

• S-cones: react to short-wave light (blue).
• M cones: react to medium-wave light (green).
• L cones: react to long-wave light (red).

The incident light hits these cones, which generate electrical signals. These signals are transmitted via the optic nerve to the brain, where they are processed and converted into the perception of colors. Our brain combines the information from the three types of cones to produce the full range of colors that we perceive.

Is this process influenced by laser eye surgery immediately after the operation?

The process of color perception is generally not directly affected by laser eye surgery. In procedures such as LASIK, Trans-PRK or Femto-LASIK, the cornea of the eye is treated to correct visual defects such as short-sightedness, long-sightedness or astigmatism. No surgical intervention is carried out on the cones in the retina or on the optical nerve pathways that are responsible for color perception.

Why might color perception change after laser treatment?

Nevertheless, some patients report after the procedure that their perception of colors has changed, usually for a short time – rarely permanently. And this cannot be ruled out, as certain effects of laser eye surgery can indirectly cause a minimal change in color perception. In most cases, however, it even changes for the better. Other side effects such as the feeling of having a foreign body in the eye or blurred vision must first disappear in order to determine whether shapes and colors are seen differently with or without visual aids.

Change in full visual acuity as a whole

Improved vision quality after laser eye surgery can also affect color perception, with colors appearing clearer, richer and more intense. This is mainly due to the fact that vision becomes sharper and more precise after the correction of visual defects such as myopia, hyperopia or astigmatism. Here are some reasons why color perception may change after the healing process or improvement in vision:

• Less stray light: In the case of defective vision, the light is not focused correctly on the retina. This can lead to a kind of “scattered light” that causes colors to fade or appear blurred. After laser treatment, the light is focused more precisely, resulting in a clearer perception of colors.
• Elimination of distortions: Visual defects such as astigmatism often lead to distortions in which colors appear less intense or blurred. The correction makes perception more harmonious, which is particularly noticeable in contrasts between colors.
• Increased contrast sensitivity: Many patients report increased contrast sensitivity after treatment, i.e. the ability to perceive differences between light and dark more clearly. This also results in colors appearing more intense in their purity.
• Relief for the visual system: Before the operation, the brain often has to work harder to compensate for blurred images. After the correction, it can concentrate fully on processing the clear visual information, which also has a positive effect on color vision.

These effects are generally positive, as they improve the overall viewing experience and make colors appear more brilliant.

Dry eyes and their effects on vision (visual impairment)

Dry eyes are a common but usually temporary side effect on the day after the operation. This dryness can affect general vision during the healing period and therefore also color perception in the days following the procedure. If the eyes are not sufficiently moisturized with tear fluid, small irregularities occur on the corneal surface. These affect the clarity of vision and can alter color perception. Fortunately, dry eyes are only temporary in most cases and can be treated well with moisturizing eye drops or adapted aftercare. As soon as the eyes recover and produce sufficient tear fluid, color perception also returns to normal. Such an effect would also occur when wearing glasses or contact lenses. So there is no need to worry.

Luminous halos, glare and colors

Halos and glare are possible temporary side effects after laser eye treatment, especially during the recovery phase. These phenomena often occur in poor lighting conditions, e.g. at night or with bright light sources, and can affect color perception. Here are the main effects:

Halos (halos):

Halos appear as luminous rings around light sources such as street lamps or headlights. They are caused by the healing of the cornea or by irregularities that may occur temporarily after laser treatment.

• Colors appear “overexposed”: Halos can cause bright colors – especially white, yellow or blue – to appear more intense and overexposed. This can make it difficult to perceive color nuances in the vicinity of such light sources.
• Reduced color depth: The halo effect can make colors appear less differentiated, as the light is scattered and the fine gradations become blurred.

Glare: Increased sensitivity to glare

Glare occurs when light is scattered on the cornea, usually due to postoperative irregularities. Bright light sources appear larger and more diffuse.

• Impairment of contrasts: Glare often reduces the contrast between light and dark colors. This makes it more difficult to see clear differences between colors, especially in high-light environments.
• Washed out colors: Glare can “wash out” colors, making them appear less intense or pale. This often affects saturated colors such as red or blue, which can lose depth in glare.

Halos and glare normally only occur in the first weeks to months after laser treatment and disappear as soon as the cornea has completely healed. This visual impairment can occur two to three weeks after laser surgery, particularly when driving in poor lighting conditions.

Temporary effects after laser surgery: Healing process and healing time after laser eye surgery

1. blurred vision

Immediately after the procedure, blurred vision is a typical side effect that can affect both visual acuity and color perception.

• Less color intensity: Colors may appear less vivid or clear because the overall quality of vision is not yet fully stable.
• Reduced contrast sensitivity: Fine differences between similar colors are more difficult to perceive, which can make colors appear washed out.

2. increased sensitivity to light

After laser treatment, the eyes are often more sensitive to light, which can also affect color vision.

• Overexposure of bright colors: In bright environments or in strong sunlight, bright colors can appear overly intense or “dazzled”.
• Difficulties with strong contrasts: A sudden change between light and dark areas can lead to a temporary shift in color perception, as the eyes adapt more slowly.

3. corneal edema (swelling of the cornea)

After laser eye treatment, there may be slight swelling of the cornea, which temporarily affects vision and thus color perception.

• Colors appear cloudy: Due to the swelling, the cornea can refract the incoming light less precisely, making colors appear less intense or blurred.
• Veil-like perception: Colors may appear through a “veil” until the swelling has subsided.

4. temporary impairment of contrast sensitivity

In the first days to weeks after laser eye surgery, the ability to see contrasts well may be impaired.

• Pale colors in low light conditions: Especially in dim light, such as at dusk or indoors, colors can appear less vibrant and more defined.
• Reduced color depth: Colors appear shallower or less deep because the eye needs time to fully adjust to the new visual acuity.

5. halo effects in daylight

Halos and glare do not only occur at night, but can also occur during the day with strong light sources or reflective light.

• Changed perception of intense colors: With halos in bright light, colors such as yellow or orange can appear more intense and radiant than before the operation, while darker tones lose intensity.

Different methods & procedures: Trans-PRK & Femto LASIK surgery

• Similarities: In the long term, there are no significant differences in color perception between the two methods. Studies have shown that both Femto-LASIK and Trans-PRK do not cause permanent changes in color vision. Once healing is complete, normal color vision returns or color vision has even improved.

Differences in the healing phase: The main differences lie in the length of the healing phase. Femto LASIK patients usually experience a faster return to normal vision quality, while trans-PRK patients have to deal with temporary effects such as halos and glare, which can affect color vision, for slightly longer.