LASIK Risks
While the overwhelming majority of patients are very pleased with the results of their LASIK, it is important for you to review potential risks and complications.
Here are three very good sources:
First: Read over the information provided on this site. We have done our best to make it as complete as possible.
Second: Discuss this information with Dr. Seibel so that it can be put in the context of your individual case.
Third: Review actual studies of risks related to laser eye surgery. Many are already included on our site.
Be sure to base your decision to have laser vision correction upon your own personal value system; avoid being influenced by friends that have had the procedure or encouraging sales personnel.
Potential complications can be divided into two distinct categories:
- Intra-operative – occurring during the procedure
- Post-operative – occurring during the healing phase
Intra-operative refers to surgical complications that occur during the procedure itself.
INTRAOPERATIVE
MICROKERATOME-RELATED
Potential intra-operative problems with LASIK typically involve the flap, and these issues are usually related to the mechanical devices and steel blades (similar to a carpenter’s plane using a razor blade), called microkeratomes. Until recently, microkeratomes been the only way to create the flap.At Seibel Vision Surgery, our LASIK procedures do not include the use microkeratomes, so any related risk factors involved are ZERO.
With the advent of the IntraLase all-laser LASIK procedure, the previously associated risks have been virtually eliminated. LASIK now utilizes the IntraLase machine to create the flap with a special cold laser. This laser was created especially for this purpose and is separate from the excimer laser (that will be used to reshape the cornea with ablation). IntraLase technology results in a safer and more precise procedure as compared to the older steel bladed technology.
Some doctors have been known to offer IntraLase as a more expensive option, thus allowing the patient to opt for older technology in order to cut expenses. However, Dr. Seibel feels that the safety and precision of IntraLase are vital and he does not offer outdated options; he will only do what is best for his patients.
Similarly, Dr. Seibel uses Wavefront technology on all LASIK approved candidates, because this gives the best potential of visual success.
EXCIMER LASER ABLATION-RELATED
As excimer laser technology and the surgical technique have been refined and advanced to include Wavefront guidance systems, complications are rarely seen today. Of the clinical studies submitted to the US FDA for approval of modern excimer laser systems, none reported decentered ablations or central islands.POST-OPERATIVE:
Surgical complications associated with the healing that occurs after the patient leaves the operating room.
These complications included corneal edema (0.6%), corneal scarring (0.1%), persistent epithelial defect (0.5%), significant glare (0.2%), persistent discomfort or pain (0.5%), interface epithelium (0.6%), cap thinning (0.1%) and interface debris (3.2%).
It is important to note that interface debris – retained metallic particles, lint, etc. under the flap – almost always causes no harm to the health or vision of the eye. None of these complications resulted in a loss of two or more lines of BCVA, and there were no infections among the study population.
Keep in mind that many advances have been made since then. A more recent study of 598 eyes noted post-operative complications in 0.9% of cases.
A number of names including Sands of the Sahara have been used to describe this condition, which is characterized by an accumulation of inflammatory cells under the flap. The condition usually appears at one to three days after LASIK. However, there have been reports of late onset DLK. Multiple causes have been hypothesized, but no single explanation accounts for all cases.
At the early stages of this condition, there would most likely be no discernible symptoms, and only an examination by your doctor could reveal its existence. When caught early, the inflammation associated with DLK is easy to treat.
Approximately 80% of DLK will clear up within the first 24 to 48 hours, although it could take several weeks until it completely subsides.
DLK can be treated without visual loss when it is detected and treated early. Therefore it is imperative that you maintain your surgeon’s recommended post-operative follow-up examination schedule.
Carefully review your immediate post-operative expectations with Dr. Seibel prior to your surgery. Review your follow-up schedule and all post-surgical instructions. Then, if you notice something about your vision that deviates from Dr. Seibel’s expectations, notify him immediately.
To remove the striae, the flap might be lifted, gently smoothed out, and then laid back down in the proper position. In cases of persistent striae, sutures may be necessary.
According to a study involving 1019 eyes, 11 eyes experienced folds in the flap that required repositioning because of poor vision. The average postoperative time for repositioning was six days. In one eye, the folds persisted to the next day, so the flap was repositioned again and sutured.
There are a number of causes of striae. Sometimes, rubbing the eyelids before the flap has had a chance to bond can cause subtle wrinkles. You can significantly reduce this risk by keeping your hands away from your eyes for several weeks after surgery.
Sometimes, striae form without an apparent cause. They seem more common in very high myopes than in other patients.
One study of 1013 eyes demonstrated a 14.7% incidence rate, with 1.7% of eyes requiring surgical removal because it interfered with vision.
Another study of 783 eyes noted only 3 eyes experienced this complication. Another study of 589 eyes noted that peripheral epithelial ingrowth occurred in 4 cases (0.6%).
In such cases, many doctors will simply leave the ingrowth alone and monitor it at post-operative visits. However, in about 1-2% (of the cases), epithelial ingrowth occurs within the field of vision or affects an area wide enough to require surgical treatment or removal.
Central visually significant epithelial ingrowth can appear as early as 1-2 days post-operatively, but most often appear at 1-3 months post-operatively. Left unattended, the cells that characterize visually significant epithelial ingrowth can release enzymes that melt the flap, causing vision loss. Therefore, it is important that you attend all follow-up visits with Dr. Seibel, especially for the first 6 months post-operatively.
Treatment usually involves prescribed eye drops to minimize the effects. At other times a more aggressive approach will be necessary. Removing the epithelial cells is a relatively simple procedure.
The flap is lifted (e.g. using the Seibel Flap Lifter or the Seibel Vari-edge Flap Lifter), the exposed interface surfaces are wiped, and the flap is then carefully replaced. In rare cases where the epithelial ingrowth persists despite such removals, sutures may be required to secure the flap down and ensure that ingrowth cannot re-occur.
The symptoms can vary widely – from being relatively asymptomatic, to intermittent dryness at certain times during the day, to feeling the typical dry sensation much or all of the day, sometimes accompanied by blurry vision or an increase in glare and halos. When dry eye is treated, those symptoms typically diminish.
Clinical dry eye is comparatively easy to diagnose and the great majority of patients respond well to treatment options ranging from using preservative-free eye drops to the insertion of punctal plugs, depending on the severity of the case. For almost all patients, dry eye symptoms gradually subside over the first few weeks or months after LASIK surgery.
As early as December 1999, ophthalmologists were paying attention to the possible connection between LASIK and dry eye. At the 1999 joint meeting of the American Academy of Ophthalmology and the Pan-American Association of Ophthalmology, the results of a survey of 550 patients after LASIK were reported. Forty to fifty percent noted experiencing dry eyes at some time of the day 3 months post-operatively. Dr. Richard Lindstrom noted that while the overall frequency of complications after LASIK is decreasing, the incidence of dry eye after LASIK is increasing. Dr. Roger Steinert supported Dr. Lindstrom’s assertion and provided a possible explanation:
Dr. Marguerite McDonald noted several other possible explanations for the increased frequency of this condition post-operatively:
Since then, several studies have demonstrated that some patients may experience a decrease in corneal sensation following LASIK for the first six months following the procedure as the nerves of the cornea regenerate.
Corneal sensation is characterized by a feedback loop. When the eye is dry, a message is sent to the brain. The brain then stimulates the eye’s lacrimal glands to produce tears. However, creating the flap cuts the nerves of the cornea. For some eyes, this process temporarily affects the cornea’s ability to respond to dryness. When corneal sensation decreases, the feedback loop is disrupted, and the eye will experience dry eye symptoms.
Dry eye symptoms may exist for patients for several months following LASIK, even if there were no symptoms or signs of dry eye prior to surgery. Those patients who have severe conditions pre-operatively need to be aware that, because surgery can exacerbate the symptoms, they may be deemed ineligible for surgery.
- Diffuse lamellar keratitis (DLK)
- Flap Striae (folds or wrinkles)
- Epithelial in growth
- Dry eyes
These complications included corneal edema (0.6%), corneal scarring (0.1%), persistent epithelial defect (0.5%), significant glare (0.2%), persistent discomfort or pain (0.5%), interface epithelium (0.6%), cap thinning (0.1%) and interface debris (3.2%).
It is important to note that interface debris – retained metallic particles, lint, etc. under the flap – almost always causes no harm to the health or vision of the eye. None of these complications resulted in a loss of two or more lines of BCVA, and there were no infections among the study population.
Keep in mind that many advances have been made since then. A more recent study of 598 eyes noted post-operative complications in 0.9% of cases.
DIFFUSE LAMELLAR KERATITIS (DLK)
Diffuse lamellar keratitis is a unique and relatively uncommon post-operative condition following LASIK. Non-severe forms have been estimated in less than 1% of cases; severe cases comprise an even lesser amount.A number of names including Sands of the Sahara have been used to describe this condition, which is characterized by an accumulation of inflammatory cells under the flap. The condition usually appears at one to three days after LASIK. However, there have been reports of late onset DLK. Multiple causes have been hypothesized, but no single explanation accounts for all cases.
At the early stages of this condition, there would most likely be no discernible symptoms, and only an examination by your doctor could reveal its existence. When caught early, the inflammation associated with DLK is easy to treat.
Approximately 80% of DLK will clear up within the first 24 to 48 hours, although it could take several weeks until it completely subsides.
DLK can be treated without visual loss when it is detected and treated early. Therefore it is imperative that you maintain your surgeon’s recommended post-operative follow-up examination schedule.
Carefully review your immediate post-operative expectations with Dr. Seibel prior to your surgery. Review your follow-up schedule and all post-surgical instructions. Then, if you notice something about your vision that deviates from Dr. Seibel’s expectations, notify him immediately.
FLAP STRIAE (FOLDS OR WRINKLES)
Flap striae are wrinkles or folds in the flap after LASIK surgery. Minor flap striae usually do not interfere with vision. In such cases, treatment is unnecessary. Occasionally, the striae are serious enough to decrease visual acuity and intervention is necessary.To remove the striae, the flap might be lifted, gently smoothed out, and then laid back down in the proper position. In cases of persistent striae, sutures may be necessary.
According to a study involving 1019 eyes, 11 eyes experienced folds in the flap that required repositioning because of poor vision. The average postoperative time for repositioning was six days. In one eye, the folds persisted to the next day, so the flap was repositioned again and sutured.
There are a number of causes of striae. Sometimes, rubbing the eyelids before the flap has had a chance to bond can cause subtle wrinkles. You can significantly reduce this risk by keeping your hands away from your eyes for several weeks after surgery.
Sometimes, striae form without an apparent cause. They seem more common in very high myopes than in other patients.
EPITHELIAL INGROWTH
Epithelial ingrowth is a condition in which epithelial cells, which normally cover the surface of the cornea, grow beneath the flap. Most epithelial ingrowth does not affect vision and does not require treatment.One study of 1013 eyes demonstrated a 14.7% incidence rate, with 1.7% of eyes requiring surgical removal because it interfered with vision.
Another study of 783 eyes noted only 3 eyes experienced this complication. Another study of 589 eyes noted that peripheral epithelial ingrowth occurred in 4 cases (0.6%).
In such cases, many doctors will simply leave the ingrowth alone and monitor it at post-operative visits. However, in about 1-2% (of the cases), epithelial ingrowth occurs within the field of vision or affects an area wide enough to require surgical treatment or removal.
Central visually significant epithelial ingrowth can appear as early as 1-2 days post-operatively, but most often appear at 1-3 months post-operatively. Left unattended, the cells that characterize visually significant epithelial ingrowth can release enzymes that melt the flap, causing vision loss. Therefore, it is important that you attend all follow-up visits with Dr. Seibel, especially for the first 6 months post-operatively.
Treatment usually involves prescribed eye drops to minimize the effects. At other times a more aggressive approach will be necessary. Removing the epithelial cells is a relatively simple procedure.
The flap is lifted (e.g. using the Seibel Flap Lifter or the Seibel Vari-edge Flap Lifter), the exposed interface surfaces are wiped, and the flap is then carefully replaced. In rare cases where the epithelial ingrowth persists despite such removals, sutures may be required to secure the flap down and ensure that ingrowth cannot re-occur.
DRY EYES
It is not uncommon to experience some symptoms of dry eyes post-operatively; especially during the first few weeks while the majority of corneal healing takes place.The symptoms can vary widely – from being relatively asymptomatic, to intermittent dryness at certain times during the day, to feeling the typical dry sensation much or all of the day, sometimes accompanied by blurry vision or an increase in glare and halos. When dry eye is treated, those symptoms typically diminish.
Clinical dry eye is comparatively easy to diagnose and the great majority of patients respond well to treatment options ranging from using preservative-free eye drops to the insertion of punctal plugs, depending on the severity of the case. For almost all patients, dry eye symptoms gradually subside over the first few weeks or months after LASIK surgery.
As early as December 1999, ophthalmologists were paying attention to the possible connection between LASIK and dry eye. At the 1999 joint meeting of the American Academy of Ophthalmology and the Pan-American Association of Ophthalmology, the results of a survey of 550 patients after LASIK were reported. Forty to fifty percent noted experiencing dry eyes at some time of the day 3 months post-operatively. Dr. Richard Lindstrom noted that while the overall frequency of complications after LASIK is decreasing, the incidence of dry eye after LASIK is increasing. Dr. Roger Steinert supported Dr. Lindstrom’s assertion and provided a possible explanation:
- Some patients seek LASIK precisely because they are contact lens intolerant, and such intolerance is often indicative of dry eyes
Dr. Marguerite McDonald noted several other possible explanations for the increased frequency of this condition post-operatively:
- Use of post-operative steroids after LASIK may exacerbate pre-existing dry eye
- Previous contact lens wear disrupts normal corneal physiology
- Hormonal changes during menopause or birth control pills can cause dry eye
- Surgery itself may cause dry eye by cutting the nerves of the central cornea or damaging cilia
Since then, several studies have demonstrated that some patients may experience a decrease in corneal sensation following LASIK for the first six months following the procedure as the nerves of the cornea regenerate.
Corneal sensation is characterized by a feedback loop. When the eye is dry, a message is sent to the brain. The brain then stimulates the eye’s lacrimal glands to produce tears. However, creating the flap cuts the nerves of the cornea. For some eyes, this process temporarily affects the cornea’s ability to respond to dryness. When corneal sensation decreases, the feedback loop is disrupted, and the eye will experience dry eye symptoms.
Dry eye symptoms may exist for patients for several months following LASIK, even if there were no symptoms or signs of dry eye prior to surgery. Those patients who have severe conditions pre-operatively need to be aware that, because surgery can exacerbate the symptoms, they may be deemed ineligible for surgery.
QUALITY OF VISION
Risks associated with laser vision surgery range from occasional minor temporary setbacks to rare major permanent conditions.
If your eye heals in a different manner (more aggressively or slower) than the “average eye”, an over or under correction of the refractive error may result.
In addition, after LASIK, the stroma (the thickest part of the cornea and where the laser ablation takes place) may experience some slight remodeling, and/or the epithelium (the thinnest and outermost layer of the cornea) may thicken.
Either of these conditions might result in a slight loss of refractive surgical effect postoperatively. This loss, or going back towards the original refraction, is called regression; this would represent a patient under-responding to the laser.
Conventionally, regression is defined as a shift in visual outcome. In this situation, the sharpness of vision that occurs soon after surgery diminishes as the eye regains a small amount of its original nearsightedness, farsightedness, or astigmatism. Regression can occur quickly, within the first few weeks after surgery, but it also can occur slowly over time.
Patients who experience regression will notice their vision changing progressively over days and weeks (not as a fluctuation during the day). Typically, the Dr. Seibel will evaluate the regression to determine its cause and review treatment options with you. An enhancement procedure can usually be performed to correct the residual error, just as is done to treat an under-correction or over-correction.
In general, the higher the correction undertaken, the more likely regression is to occur;this is especially true for treatment of hyperopia greater than +5 diopters, which may benefit more from Clear Lens Extraction.
In most cases, under-correction (where the patient’s cornea responds insufficiently to yield the desired change in vision) and regression (where part of the surgical effect is lost during the healing process) can be treated with an enhancement procedure.
An over correction of myopia may be corrected by performing a hyperopic LASIK enhancement, whereas a hyperopic over correction would, in most cases, be correctable using a myopic LASIK enhancement.
However, eyes with very thin or steep corneas or high degrees of refractive errors may not be eligible for enhancements. If this refers to you, be sure to speak with Dr. Seibel about your potential eligibility for an enhancement.
If you are among the relatively few people who significantly over-respond or under-respond to the laser treatment, Dr. Seibel will discuss your treatment options. Generally, he prefers to wait approximately 3-6 months to perform an enhancement to ensure that the final vision has been achieved.
As that point, either a hyperopia or myopia LASIK procedure will be performed to correct the residual error, if you and Dr. Seibel believe it is appropriate. This is typically accomplished by gently relifting the original LASIK flap rather than creating a new one.
These symptoms usually subside within a few days or weeks for the vast majority of patients who experience them. However, some will continue for a greater length of time and there may be a need to wear glasses to drive at night. These effects are most usually temporary, but could be permanent and uncorrectable.
There are several potential causes of decreased night vision. The most common is the normal mild swelling of the LASIK flap, which resolves within a few weeks of surgery.
Many researchers believe that patients who have pupils that exceed the ablation zone may be more likely to experience decreased night or low-light vision following LASIK than the general population. Another cause is incomplete correction of the nearsightedness, farsightedness or astigmatism; this is probably more significant than pupil size according to recent research performed by Dr. Steve Schallhorn at the Navy Medical Hospital. Clinical dry eye can also contribute to the experience of glare and halos.
- Over-correction, Under-correction or Regression
- Night or dim-light vision complications
- Increased light sensitivity or fluctuating vision
- Optical imbalance in eyes
OVER-CORRECTION, UNDER-CORRECTION & REGRESSION
Every eye heals differently. Surgical plans are generally based upon an “average eye” healing response. Recall that these plans are typically quite accurate for most people, yielding a 98% rate of 20/20 vision after 12 months in the FDA validation study of VISX CustomVue in which Dr. Seibel was an investigator.If your eye heals in a different manner (more aggressively or slower) than the “average eye”, an over or under correction of the refractive error may result.
In addition, after LASIK, the stroma (the thickest part of the cornea and where the laser ablation takes place) may experience some slight remodeling, and/or the epithelium (the thinnest and outermost layer of the cornea) may thicken.
Either of these conditions might result in a slight loss of refractive surgical effect postoperatively. This loss, or going back towards the original refraction, is called regression; this would represent a patient under-responding to the laser.
Conventionally, regression is defined as a shift in visual outcome. In this situation, the sharpness of vision that occurs soon after surgery diminishes as the eye regains a small amount of its original nearsightedness, farsightedness, or astigmatism. Regression can occur quickly, within the first few weeks after surgery, but it also can occur slowly over time.
Patients who experience regression will notice their vision changing progressively over days and weeks (not as a fluctuation during the day). Typically, the Dr. Seibel will evaluate the regression to determine its cause and review treatment options with you. An enhancement procedure can usually be performed to correct the residual error, just as is done to treat an under-correction or over-correction.
In general, the higher the correction undertaken, the more likely regression is to occur;this is especially true for treatment of hyperopia greater than +5 diopters, which may benefit more from Clear Lens Extraction.
In most cases, under-correction (where the patient’s cornea responds insufficiently to yield the desired change in vision) and regression (where part of the surgical effect is lost during the healing process) can be treated with an enhancement procedure.
An over correction of myopia may be corrected by performing a hyperopic LASIK enhancement, whereas a hyperopic over correction would, in most cases, be correctable using a myopic LASIK enhancement.
However, eyes with very thin or steep corneas or high degrees of refractive errors may not be eligible for enhancements. If this refers to you, be sure to speak with Dr. Seibel about your potential eligibility for an enhancement.
OVERALL:
- Nearsighted patients who experience an over-correction become farsighted and notice that they can no longer see near objects as well
- Nearsighted patients who have been under-corrected notice that objects in a distance are still not perfectly clear although vision is still typically better than preoperatively
- Farsighted patients who experience an over correction become nearsighted and notice that objects at a distance are still blurred although near objects can be seen more clearly.
- Farsighted patients who have been under-corrected notice that both far and near objects are not totally in focus, just as with the original hyperopia, although typically still improved from the pre-LASIK vision.
If you are among the relatively few people who significantly over-respond or under-respond to the laser treatment, Dr. Seibel will discuss your treatment options. Generally, he prefers to wait approximately 3-6 months to perform an enhancement to ensure that the final vision has been achieved.
As that point, either a hyperopia or myopia LASIK procedure will be performed to correct the residual error, if you and Dr. Seibel believe it is appropriate. This is typically accomplished by gently relifting the original LASIK flap rather than creating a new one.
NIGHT OR DIM-LIGHT VISION COMPLICATIONS
Many LASIK patients notice a temporary decrease in vision at night or in dim light with symptoms that include decreased contrast sensitivity, glare, halos, and starbursts. The experience of these phenomena can range from mild to severe.These symptoms usually subside within a few days or weeks for the vast majority of patients who experience them. However, some will continue for a greater length of time and there may be a need to wear glasses to drive at night. These effects are most usually temporary, but could be permanent and uncorrectable.
There are several potential causes of decreased night vision. The most common is the normal mild swelling of the LASIK flap, which resolves within a few weeks of surgery.
Many researchers believe that patients who have pupils that exceed the ablation zone may be more likely to experience decreased night or low-light vision following LASIK than the general population. Another cause is incomplete correction of the nearsightedness, farsightedness or astigmatism; this is probably more significant than pupil size according to recent research performed by Dr. Steve Schallhorn at the Navy Medical Hospital. Clinical dry eye can also contribute to the experience of glare and halos.
- Decreased contrast sensitivity
Contrast sensitivity deals with a patient’s ability to discern images of varying shades from the background – in other words, how faded an image can be before it is indistinguishable from the background.Imagine driving in fog – the thicker the fog, the grayer all objects become and the more difficult to distinguish their features. Because contrast sensitivity is important to the quality of vision, several studies have been conducted over the last several years to determine the affect of LASIK on it.
- All noted a decrease in contrast sensitivity, which lasted from one to six months post-operatively.
- However, all but one also noted a return to pre-operative function by the six-month visit.
- The first assessed 174 eyes that were treated between November 1997 and October 1998. Of them, 29% reported reduced night vision – however, it’s important to note that 97% of patients indicated they would decided to have LASIK again.
- The second involved questionnaires sent to 50 patients; 8.8% reported difficulty with nighttime driving. Again, 98% noted overall satisfaction with their outcomes.
Many improvements and technological advancements have been made since that time. The “Summary of Safety & Effectiveness Data” required by the United States FDA tabulates the subjective reporting of glare, halos and difficulty with nighttime driving pre-operatively and post-operatively at various time intervals.
Overall, two reports noted improvement of nighttime vision as compared to the pre-operative assessment and one noted a split, with between 5-9% of patients noting a significant improvement and the same number noting the symptoms were significantly worse.
Using the latest technology with the VISX CustomVue Wavefront system, more patients were satisfied or very satisfied with their night vision without glasses or contacts after LASIK compared to their level of satisfaction with glasses or contacts before LASIK. - Glare/halos/starbursts Those patients who experience persistent glare, halos or starbursts do have several treatment options, including prescription eye drops to help constrict the pupil at night to reduce the symptoms of decreased night vision.This pharmaceutical approach is not successful for all people, and it also can represent a significant expense over time. Similarly, enhancement procedures may be an option, though not everyone is eligible for an additional procedure. Eligibility for enhancements depends on a number of factors that a doctor must evaluate.