Night vision and Refractive surgery: A comprehensive overview

PRK surgery has empowered millions to achieve clear, natural vision free from the constraints of glasses or contacts. But what about when the lights go out? Does PRK surgery affect your ability to see in low-light conditions? Some individuals may experience halos, glare, or difficulties driving at night after PRK surgery. This blog will explore the relationship between PRK surgery and night vision, uncovering the potential causes of these symptoms. More importantly, it will provide practical strategies to mitigate their impact, empowering you to confidently navigate your surroundings, even in the dark.

Night vision, the ability to perceive objects in low-light settings, is a complex process that depends on various factors. These factors, such as pupil size and sensitivity to contrast, can potentially impact night vision. Understanding these factors is crucial for managing any related issues.

• Higher-order aberrations (HOAs): These intricate vision defects, including spherical aberration and coma, are not corrected by spectacles or contact lenses and can affect night vision.

• Pupil Size: The pupils dilate at night to enable increased light penetration into the eye. Halos and glare can be caused by the pupil dilation going beyond the area that the PRK laser reshapes

• Sensitivity to Contrast: Corneal surface alterations can impact low-light contrast sensitivity.

PRK, a corneal reshaping procedure, can have a significant impact on night vision, as it enhances light focus on the retina. This effect can be either temporary or permanent.

How Is Night Vision Affected by PRK Surgery?

An excimer laser reshapes the cornea's surface to correct refractive defects during PRK surgery. This distortion can alter how light reaches the retina, especially in dim lighting.

Some ways PRK could impact night vision are as follows:

1. Glare: Some patients experience glare after PRK, characterized by an elevated sensitivity to solid lighting. Nighttime driving or staring at headlights or streetlights can cause glare.

2. Halos: These ethereal circles can be seen surrounding several types of light sources, including headlights, streetlights, or signage that is lighted. When the pupil is dilated at night, halos are more evident.

3. Starbursts: These dazzling lights produce beams that resemble stars and frequently combine with glare and halos. Because of this, the appearance of light sources might be distorted.

4. Diminutive Sensitivity: Some individuals may have trouble differentiating items against low-contrast backgrounds, such as nighttime driving on a dark road. This can make driving at night or in low-light conditions more difficult.

5. Higher-Order Aberrations (HOAs): PRK can occasionally exacerbate HOAs, particularly if the surgery is not well-centered or the corneal reshaping is irregular. When the pupil is dilated in low light, these aberrations can cause visual distortion.

Why does PRK affect night vision?

After PRK surgery, your night vision may vary for a few reasons:

1. Corneal Remodelling and Healing: Following PRK, the cornea goes through a healing phase, during which new corneal tissue is formed and the epithelium is replaced. Over a few weeks or months, the cornea's surface may become uneven, which can temporarily impair night vision.

2. Inconsistency in Pupil Size: PRK laser reshaping is usually customized for a specific optical zone. As the pupil dilates outside this treated zone at night, glare and halos can form due to light penetrating the untreated corneal periphery.

3. Corneal Haze: PRK can occasionally create corneal haze as a normal part of the healing process. This haze's ability to disperse light and diminish visual acuity can exacerbate glare, halos, and starbursts.

4. Patient History: Post-PRK night vision problems may be more common in patients with more prominent pupils, heavier prescriptions, or pre-existing higher-order aberrations.

5. Laser Technology and Treatment Zones: Contemporary PRK relies on sophisticated laser technology and custom treatments to mitigate night vision issues. However, the size of the treatment zone and its alignment with the patient's pupil size are critical factors.

How Long Does It Take to See at Night After PRK?

Glare, halos, and starbursts are common night vision problems that may occur after PRK surgery. However, these issues usually diminish as the eyes recover. Here's what you can expect:

• Night vision disturbances are typically most severe during the initial healing phase, which covers the first few days to weeks. The cornea heals, and the epithelium regenerates, although patients may notice severe glare, halos, and diminished contrast sensitivity at this time.

  
  

  Visual disturbances typically diminish as the cornea stabilizes, usually within 1 to 3 months. The night vision of the majority of patients is significantly enhanced within the first three months. Within three to six months following PRK surgery, most patients no longer experience night vision problems. Night vision may take longer to stabilize for specific individuals, especially those with high prescriptions or big pupils.

  
  

• After 6 Months: Night vision problems that last longer than six months are less prevalent. If these materialize, more testing may be necessary to determine the best course of action, including augmentation procedures or individualized wavefront-guided PRK.

Managing Night Vision Issues Following PRK

After PRK surgery, there are a variety of methods to deal with problems at night:

1. Wearing Anti-Glare Glasses: People who have trouble seeing in low light or at night may find that anti-reflective coated glasses help.

2. Medications and Eye Drops: Medications and lubricating eye drops can alleviate dryness and discomfort, which might sometimes worsen night vision problems. Some patients may be prescribed drops that narrow the pupil while sleeping to lessen the severity of untreated peripheral cornea.

3. Be patient and allow yourself time: Know that having trouble seeing at night is expected when you're recuperating. This will help you have reasonable expectations. As the cornea stabilizes, most patients experience significant improvement over time. Patients with chronic higher-order aberrations may find relief from their symptoms and improve their night vision with bespoke wavefront-guided PRK, which involves refining the corneal shape.

4. Custom wavefront-guided PRK can be a game-changer for patients with persistent higher-order aberrations. This advanced procedure can refine the corneal shape, thereby reducing these aberrations and significantly enhancing night vision.

5. Staying Away from High-Contrast Areas: To lessen the effects of glare and halos, try not to stare at bright lights in dark places, such as a phone screen in a completely black room.

Who is More Likely to Have Problems with Their Night Vision After PRK?

Some patients may be more likely to have problems seeing at night following PRK:

Some patients may be at an increased risk of experiencing night vision disturbances following PRK. Glare, halos, and starbursts are more common in low light, so taking extra precautions with patients with naturally big pupils is essential.

• Patients with naturally large pupils are more susceptible to experiencing dazzle, halos, and starbursts, particularly in low-light conditions.

• High Prescription Patients: The extensive corneal reshaping necessary may increase the risk of night vision issues for individuals with high levels of myopia or hyperopia. Patients with higher-order aberrations or corneal topography irregularities may have more difficulty seeing at night after surgery.

PRK surgery may result in temporary changes to night vision, including sparkle, halos, starbursts, and diminished contrast sensitivity, which may occur during the healing process. As the cornea heals and stabilizes, these problems usually disappear for most patients. Knowing the risks involved, anticipating a recovery period, and adhering to post-operative care recommendations can help you better manage your expectations and get the best possible results from your surgery.

If you are worried about having trouble seeing at night after PRK or have a higher risk profile, booking a free consultation at Eagle Eye Care can help you determine the best course of action based on your needs and vision goals.