Why LASIK, PRK, SMILE and cataract surgery can affect the ocular surface.
Dry eye is a well-recognised consequence of LASIK, PRK, SMILE, cataract surgery and other ocular procedures. This does not mean that these surgeries inevitably cause chronic dry eye. For many people, postoperative changes are temporary.
But surgery can disturb several parts of the ocular-surface system at the same time, and in some patients that disturbance can persist.
There is no single mechanism. Depending on the procedure, surgery can affect:
Postoperative eye drops and preservatives can add another source of ocular-surface stress. And sometimes surgery does not create an entirely new problem. Instead, it can worsen pre-existing dry eye or MGD that was already present before the procedure.
The cornea contains an extraordinarily dense network of sensory nerves. Those nerves allow us to feel the ocular surface, but that is only one of their jobs. They are part of the feedback system that helps regulate:
When corneal surgery cuts or disrupts some of those nerve fibers, communication within this system temporarily changes. This is particularly important after refractive surgery. After LASIK, for example, corneal denervation has been proposed as a major mechanism behind postoperative reductions in corneal sensitivity, tear secretion and tear-film stability.
During LASIK, a corneal flap is created and the underlying corneal tissue is reshaped. Creating the flap and performing the ablation transects corneal nerves. After surgery, studies have documented changes including:
The nerves subsequently begin to regenerate. For many patients, ocular-surface function and symptoms improve as healing progresses. But recovery is not identical in everyone.
Usually, postoperative dry-eye changes improve with time. A review of post-LASIK dry eye describes symptoms and signs as generally most prominent early after surgery, with a much smaller group continuing to experience symptoms beyond one year. But it would be equally inaccurate to say:
“Post-LASIK dry eye always disappears.”
Some people do experience persistent symptoms. And when symptoms remain long after the ocular surface appears to have recovered, we need to consider another possibility: the nervous system itself may be contributing to the symptoms.
Yes. PRK, or photorefractive keratectomy, does not create a corneal flap. Instead, the corneal epithelium is removed and the underlying tissue is reshaped with a laser. PRK still disrupts corneal nerves and can produce temporary postoperative dry-eye changes.
But because the surgical techniques are different, their effects on corneal innervation and the ocular surface are not identical. A meta-analysis comparing several refractive procedures found a significant postoperative reduction in tear-film break-up time and tear production after LASIK, while pooled changes for PRK were smaller and not statistically significant in those particular analyses. That does not mean PRK cannot cause postoperative dry eye. It means the magnitude and pattern of ocular-surface disturbance differ between procedures.
SMILE, or small-incision lenticule extraction, reshapes the cornea through a much smaller incision and does not create a LASIK-style flap. Because fewer anterior corneal nerves are transected, SMILE was expected to have less effect on corneal innervation.
Comparative studies generally support that idea. Both LASIK and SMILE can temporarily worsen dry-eye parameters, but SMILE tends to preserve corneal sensitivity and nerve density better and may produce less postoperative ocular-surface disturbance, particularly during early recovery. But SMILE does not mean zero dry-eye risk. Dry-eye symptoms can still occur after SMILE.
So which refractive surgery is “best” for dry eye? There is no universal answer based on dry-eye risk alone. LASIK, PRK and SMILE differ in:
Dry-eye risk is only one part of surgical decision-making. What is particularly important is recognizing pre-existing ocular-surface disease before surgery.
Because sometimes the surgery is blamed for a problem that was already developing before it. A person may already have:
Symptoms may have been mild or intermittent before surgery. Then the additional stress of surgery can make them much more noticeable. Post-refractive dry-eye reviews consistently identify pre-existing ocular-surface disease as an important consideration before surgery.
This is why a proper preoperative ocular-surface assessment matters.
Cataract surgery is very different from LASIK. The cloudy natural lens inside the eye is removed and replaced with an artificial intraocular lens. But the procedure can still affect the ocular surface. Corneal incisions can disrupt corneal nerves. Surgical manipulation can produce inflammation. Postoperative topical medications, sometimes used several times per day, can also affect an already vulnerable ocular surface.
A recent review describes both cataract surgery and LASIK as capable of causing or exacerbating ocular-surface disease through overlapping mechanisms including corneal nerve disruption, tear-film instability, altered blink reflexes and postoperative topical treatment.
Not usually. Many postoperative ocular-surface changes improve during recovery. But again, individual responses vary. Older patients undergoing cataract surgery may already have dry eye or MGD before the procedure, sometimes without realizing it.
So cataract surgery can sometimes reveal or worsen a pre-existing ocular-surface problem rather than creating the entire condition from nothing. That distinction can matter when trying to understand persistent symptoms afterward.
Yes. After ocular surgery, patients may temporarily use several topical medications. The active ingredients themselves can sometimes affect the ocular surface, and repeated exposure to preservatives may add further stress in susceptible eyes. A 2025 review of LASIK and cataract surgery specifically identifies preservatives in perioperative topical medications as one factor that may exacerbate postoperative ocular-surface symptoms.
This does not mean postoperative drops should be avoided. They are prescribed for important reasons, including controlling inflammation and preventing infection. It simply means they can be another piece of the ocular-surface picture.
MGD is particularly important before and after eye surgery. A patient may already have abnormal meibomian gland function before surgery. If tear-film stability then decreases after the procedure, the pre-existing lipid-layer problem can become more clinically important. This creates a familiar problem: was the MGD caused by the surgery?
Not necessarily. It may have existed before surgery, worsened afterward, or become symptomatic only after the ocular surface was subjected to additional stress. Again, chronology matters.
Meibomian Gland Dysfunction (MGD) — coming soon
Corneal nerve recovery is gradual. Sensitivity may improve substantially within months, but anatomical nerve regeneration and functional recovery do not necessarily occur at exactly the same rate. And a nerve network that has regrown is not necessarily identical to the original network. This is one reason why it is too simplistic to say:
“The nerves grow back, therefore everything returns to exactly how it was before.”
Research after LASIK has found substantial recovery in corneal sensitivity and clinical dry-eye parameters over time while also documenting longer-lasting alterations in corneal innervation in some patients.
Yes. And this is especially important after procedures involving the cornea. One patient may have obvious tear-film abnormalities but relatively little discomfort. Another may have severe burning, dryness or pain despite comparatively modest surface findings. This symptom–sign mismatch is not unique to surgery, but corneal nerve injury makes neural mechanisms particularly relevant after refractive procedures.
So when symptoms are severe or persistent, the question should not always be “Which dry-eye test are we missing?” Sometimes another question is needed: “Could abnormal corneal sensation or neuropathic pain be part of this picture?”
One of the most useful steps is identifying ocular-surface problems before surgery. That may include evaluating:
When significant ocular-surface disease is present, treating or stabilizing it before elective surgery may improve the situation going into the procedure. Post-LASIK reviews specifically emphasize careful preoperative assessment and management in patients with existing dry eye.
Not necessarily. Timing is important. If symptoms begin immediately after surgery, the procedure is obviously a relevant potential contributor. But causality can still be multifactorial.
Perhaps there was already MGD. Perhaps contact lenses had affected the ocular surface for years. Perhaps the surgery altered corneal innervation. Perhaps postoperative medication added further surface stress. Perhaps several of these occurred together.
So instead of asking only “Did the surgery cause my dry eye?” it may be more useful to ask “What changed after surgery, and which abnormalities are still present now?”
Not necessarily. Persistent symptoms do not automatically mean that the ocular surface remains physically injured in exactly the same way it was immediately after surgery. Several possibilities may exist:
Those mechanisms require different ways of thinking about the problem. This is why persistent post-surgical symptoms deserve a fresh evaluation rather than simply repeating “You still have postoperative dry eye.”
Stapleton F, et al. TFOS DEWS III: Digest.
Recognizes surgical procedures alongside medications and contact lenses as causes of iatrogenic dry-eye disease.
Toda I. Dry Eye After LASIK.
Review of corneal denervation, tear and blink reflex changes, recovery and persistent symptoms after LASIK.
Post-refractive Surgery Dry Eye: A Systematic Review Exploring Pathophysiology, Risk Factors, and Novel Management Strategies.
Reviews nerve injury, inflammation, lacrimal dysfunction, risk factors and management following refractive surgery.
Dry Eye After SMILE.
Review comparing ocular-surface and corneal-nerve effects of SMILE and femtosecond LASIK.
Ocular Surface Disease Following LASIK and Cataract Surgery: A Review of Their Interrelated Complications.
Reviews nerve injury, tear-film instability, blink changes, inflammation and topical medication exposure after both procedures.