LASIK Refractive Program at Vance Thompson Vision

LASIK Top Line

  • Age — patient must be at least 18 years old and have a stable refraction.
  • Myopia* — up to -11.00 D
  • Hyperopia* — up to +6.00
  • Astigmatism* — up to -6.00 D

*The above indications are only valid if there’s enough corneal thickness.

  • Corneal Thickness — at least 500 microns of total corneal tissue prior to surgery.

Corneal Thickness Following LASIK:

  • The posterior residual cornea should be equal to or greater than 300 microns
  • The total corneal thickness should never be less than 400 microns

Make sure patients are not rubbing their eyes.

Treat dry eye aggressively pre- and post-op.

Be on alert for epithelial ingrowth, especially with enhancements.

Pred/Gati: 1 drop qid x 1 week, bid x 1 week then D/C.

Non-preserved Artificial Tears: prn or as directed for the first three months. After that, it’s ok to use an artificial tear with a preservative

*All drops should be spaced out 10 minutes to avoid washing the first drops out.

For the most updated Post-Op Report Form, please email [email protected]

VTV has both Wavefront Guided (Visx) and Wavefront Optimized (Wavelight) excimer lasers.

VTV has both IntraLase iFS and Alcon FS 200 femptosecond lasers for flap creation.

For the most updated Referral Form, please email [email protected]

What is the procedure?

At Vance Thompson Vision, we feel that we have minimized risk and improved the quality of outcomes through our experience and commitment to technology. We can now perform three different methods of LASIK including: conventional, wavefront optimized, and wavefront guided LASIK. We exclusively use the femtosecond lasers (IntraLase iFS and Alcon FS 200) to create the flap because of its safety and accuracy. Two of the biggest improvements in LASIK have been the advent of the customized wavefront guided/optimized ablation and the femtosecond laser. In the past, if we were to see any complications, they were either blade flap complications or a reduced nighttime image quality from the induction of high order aberrations (HOA). With our femtosecond laser and customized wavefront guided/optimized lasers, we feel that we have lessened procedural risk and helped patients retain a crisp nighttime image quality. The femtosecond lasers have also reduced the risk for any “flap surprises” (i.e. partial flaps, free caps or buttonhole flaps, which could create a scar over the pupil).

Our corneal thickness calculations are now more predictable because of the precision of the femtosecond lasers. Further, they can make a thinner flap in the cornea, enabling us to do higher prescriptions. Another advantage the femtosecond lasers have over blade LASIK is that the femtosecond lasers create a much more accurate flap, with consistent flap thickness across the entire flap. This flap, which has even thickness from edge to edge, is called a planar flap. A planar flap lessens the induction of higher order aberrations (HOAs). And, studies have shown that to get the best outcomes, a customized wavefront guided or optimized ablations should be preceded by a laser controlled flap maker: the Intralase iFS or Alson FS 200. A flap made by a microkeratome is thicker at the edges than it is in the center. This variance in blade flap thickness increases the chance of a buttonhole and can induce some HOAs, which can hinder a person’s nighttime image quality.

When and Why Do It?

  • Age — patient must be at least 18 years old and have a stable refraction.
  • Myopia* — up to -11.00 D
  • Hyperopia* — up to +6.00
  • Astigmatism* — up to -6.00 D

*The above indications are only valid if there’s enough corneal thickness.

Corneal Thickness — at least 500 microns of total corneal tissue prior to surgery, dependent upon Rx.

Corneal Thickness Following LASIK:

The posterior residual cornea should be equal to or greater than 300 microns

The total corneal thickness should never be less than 400 microns

Our corneal thickness calculations are as follows:

[Total Overall Corneal Thickness - Flap Thickness (usually 110 microns) - Tissue Removed (usually 15-20 microns/diopter)] = Posterior Residual “Untouched” Cornea.

PRE-OPERATIVE EXAMINATION

As with all refractive procedures, an exhaustive ocular examination is performed to ensure LASIK as the best procedure for our prospective patient. Further, to get the most accurate measurements, we like to have our patients out of their soft contact lenses 2 weeks and their RGPs 4-6 weeks prior to getting pre-operative measurements.

Also, to minimize post-operative complications, it’s important to be very sensitive to surface dryness. A thorough evaluation of the meibomian glands and tear film (TBUT, anesthetized shirmers, flurouscein and lisamine green staining and LipiView meibomian gland imaging) is very important in detecting any tear film abnormalities (See: Ocular Surface and Anterior Segment Surgery Tab for further information on importance of rehabbing the tear film prior to refractive surgery).

Pre-op measurements: VA (with and without correction, distance and near), manifest refraction, cycloplegic refraction, pupil size (photopic and scotopic), IOP, slit lamp exam, endothelial cell count (if any guttata are seen), Oculus Pentacam, ORA (Ocular Response Analyzer), Wavefront Analysis, and a dilated fundus exam (See: Diagnostic Technology Advances Tab for description of these instruments). While all these pre-operative measurements are very important, it is equally important to take into consideration the patient’s dominant eye, age, occupation, goals and expectations. Also, we like to have a good discussion with the patient regarding how they use their vision on a daily basis. With this information, we can tailor the best, safest refractive surgery procedure to meet their goals and expectations allowing them to perform these daily activities with less dependency on their glasses or contacts.

MYOPIA DISCUSSION

When discussing LASIK with our myopic patients, we take six key factors into consideration. These factors include: refractive error, pupil size, corneal thickness, low light image quality and wavefront analysis, age and eye rubbing.

We split refractive error into 3 groups:

Mild (plano to -2.00D)

Moderate (-2.00 to -6.00 D)

High (-6.00 D and above)

A patient with a mild refractive error (Plano to -2.00D) can usually choose either a conventional or a customized LASIK. However, if a patient with a mild refractive error has a large night-time pupil, poor low-light image quality and lots of high order aberrations (HOA), then we would recommend a customized (WFG or WFO)) ablation. Another good reason for a customized treatment, regardless of refractive error, would be if a patient is a truck driver or has an occupation where night-time vision is critical.

Patients with a moderate refractive error (-2.00 to -6.00) will almost always benefit from a Customized (WFG or WFO) treatment. Even if a person has a small pupil, a good night-time image quality and minimal HOAs, a customized treatment will lessen the induction of HOAs and keep the person’s night-time image quality as clean as possible. We do feel comfortable, in some cases, with a conventional treatment if the patient has a refractive error less than -4.00, a small pupil, a great night-time image quality and a clean wavefront, as long as the patient understands that there is an increased risk of HOA induction resulting in glare/halos at night.

A patient with a high refractive error (-6.00 and above) will almost exclusively receive a customized (WFG or WFO) treatment. The only exception would be if the refractive error is too high or the cornea is too thin. In this instance, the patient is best suited either for a phakic IOL (PIOL), Refractive Lens Exchange (RLE) or nothing at all. We’ve found that when too much corneal tissue is removed or when the cornea is made too flat (<35 diopters), the visual quality may be reduced. In these cases, a PIOL or RLE will often give the patient better visual quality than LASIK.

THE PRESBYOPIC MYOPE

Patients older than 45 to 50 years of age with a clear lens and good night time image quality can achieve great results with conventional or customized LASIK. However, these patients may start to demonstrate some early lens changes. And, sometimes it is hard to appreciate early lenticular changes with the slit lamp alone. So, for these patients, we like to ask about night time image quality and perform an Oculus Enhanced Pentacam to assess lens density, an HD Analyzer to assess light scatter, an ITrace to distinguish between corneal and lenticular aberrations (Figures 1 and 2). If we are concerned about any lenticular changes a refractive lens exchange or waiting until a visually significant cataract forms would be the best option.

HYPEROPIA DISCUSSION

When discussing LASIK with our hyperopic patients, we take into consideration the same components that we do with our myopic patients: refractive error, pupil size, corneal thickness, low light image quality, wavefront and Oculus Pentacam measurements, and age.

Patients younger than 45 to 50 years of age, with a refractive error of <+5.00, and a clear lens can benefit from conventional or customized LASIK. These same patients with a refractive error of >+5.00 to +6.00 typically have better visual outcomes with a PIOL or RLE. The reason patients with >+5.00 have better visual quality from a PIOL or RLE than with LASIK is that when we steepen a cornea too much with laser , a patient’s visual quality can decrease.

THE PRESBYOPIC HYPEROPE

Patients older than 45 to 50 years of age with a clear lens and good night time image quality can achieve great results with conventional or customized LASIK. However, these patients may start to demonstrate some early lens changes. And, sometimes it is hard to appreciate early lenticular changes with the slit lamp alone. So, for these patients, we like to ask about night time image quality and perform an Oculus Enhanced Pentacam to assess lens density, an HD Analyzer to assess light scatter, an ITrace to distinguish between corneal and lenticular aberrations (Figures 1 and 2). If we are concerned about any lenticular changes a refractive lens exchange or waiting until a visually significant cataract forms would be the best option.

PRESBYOPIA DISCUSSION

With all our presbyopic patients, whether they’re myopic or hyperopic, we discuss with them four different techniques to correct their vision.

Option #1:

We can correct both eyes for distance and have the patient wear reading glasses, bifocals, or trifocals for intermediate and near vision.

Option #2:

We can perform a “modified” monovision, in which we correct one eye (typically the dominant eye) for distance and the other eye for intermediate; we instruct the patient to wear readers for near.

Option #3:

The third option we have is a “full” monovision, in which we correct one eye (typically the dominant eye) for distance and the other eye for near. This will usually only be done if the patient has already adapted to this form of monovision with contact lenses. If this is the case, we can duplicate this vision with LASIK.

Option #4:

We can perform LASIK in both eyes followed by the Kamra corneal inlay in the non-dominant eye a month later. This works best if the non-dominant eye is targeted around -0.50 to -0.75. The advantage of the combination LASIK and Kamra is that it won’t blur distance as much and achieve better near vision. (See Corneal Inlay Section)

Absolute Contraindications: keratoconus, active herpes zoster ophthalmicus, cataracts

Relative Contraindications: endothelial dystrophies (cell counts <1500), monocular patients, abnormal eyelid closure, anterior basement membrane dystrophy, active autoimmune or collagen vascular disease, pregnant or nursing, unstable or uncontrolled diabetes, progressive myopia or hyperopia, uncontrolled glaucoma, active or residual diseases likely to affect wound healing, dry eye syndrome, forme fruste keratoconus, pellucid marginal degeneration, reduced best corrected VA, and inactive herpes (which can be reactived by the laser).

LASIK After Previous Corneal Surgery

Patients who have had previous LASIK can have their flap lifted and have more LASIK as long as there is enough room under the previous LASIK flap (usually within 2 years from prior LASIK procedures). Special attention also needs to be paid to the flap edges when deciding whether to lift the flap or perform PRK over the previous flap. If there is any irregularity at the flap edge there could be an increased risk of epithelial ingrowth and PRK would be a better option.

Patients with a history of RK or PKP can still have LASIK. Although RK is not a contraindication to LASIK, there is a risk that an incision can separate, especially when an incision is spilt or has epithelial plugs in it. Most of the time, the femtosecond is the best mechanism to create the flap in these RK patients, otherwise we will consider performing PRK. LASIK can be performed successfully on patients after PKPs. Corneal scars usually do not present difficulties in LASIK, but must be evaluated carefully to determine that they are well-healed and and not visually significant. If the scar is visually significant, it should be removed with PTK and then LASIK performed at a later date.

HOW IS THE PROCEDURE DONE?

The LASIK procedure is divided into two stages: making the flap and reshaping the cornea. The actual LASIK procedure itself takes approximately 10 minutes. We use a topical anesthetic to numb the eye and offer Valium to help calm people’s nerves. A lid speculum is placed to control blinking and provide adequate corneal exposure. Most patients feel that this is a relatively painless procedure. Most will say that the first 15 seconds of the procedure, the flap making step, is where they feel pressure from the suction ring. During this stage their vision will go dim. After the flap has been made, most patients’ vision is blurry for the rest of the procedure. The next step is reshaping the cornea by removing corneal tissue. During this step, the patient is instructed to focus on the fixation light. The laser tracker is engaged and the laser procedure is performed. Following this step, the flaps are laid back down and smoothed into position.

We utilize both Wavefront guided and Wavefront optimized platforms. The advantage of having both technologies available is that we can customize our treatments according to what best fits the patient’s needs. Wavefront guided technology works great for patients who have 0.3 or more of high order aberrations. Wavefront optimized works great for patients with less than 0.3 of high order aberration or for patients 45 years of age and older where we would be concerned about lenticular changes affecting our wavescan.

Risks

In the past, we would typically see two different types of complications: flap-related complications and reduced low-light image quality. With the advent of the femtosecond and Wavefront guided and optimized laser vision correction, we feel that we have minimized risk as much as any laser center in the world. However, we are working with human tissue and every eye responds to the laser differently and has a different healing tendency.

Most post operative complications are flap related. Some of these flap complications include: button hole flaps, partial flaps, poor night-time vision and free flaps all of which typically result from blade LASIK. These blade flap complications can be visually devastating. Thus, it is important that all our patients understand the difference between flaps created with blades and flaps created with lasers.

Flap striae is another common flap complication. Sometimes striae affect the vision enough to warrant lifting and smoothing the flap. One way to determine if striae are affecting the vision enough to need a smooth will be at your one week refraction. If the BCVA is less than 20/20 and the striae are central, the flap should be smoothed. If the refraction results in a “crisp” 20/20, the striae are not visually significant and will usually “iron” themselves out over time (Figure 4).

Although it is one of the most common complications in LASIK, epithelial ingrowth requiring surgical intervention occurs in approximately 1% of the LASIK population. It is usually detected within the first month following surgery. One of the primary causes of epithelial ingrowth is dry eye syndrome. In most cases, patients with epithelial ingrowth are asymptomatic. Epithelial ingrowth can cause a stromal melt within weeks. Thus, it is important to refer all epithelial ingrowth back to us. This way a decision can be made whether or not to lift the flap and clean.

Another type of complication that we see in our center is photophobia, especially at one month post-op after LASIK. We can start this patient on a steroid q.i.d. for one week and typically reduce the photophobia. It is important to assess these patients’ tear film. Many of these patients have dry eye that is contributing to this photophobia needs to be treated.

Diffuse lamellar keratitis (DLK), or “Sands of the Sahara” is another type of LASIK complication. This flap interface inflammation is usually seen starting at the edges of the flap at the 1 day or 1 week post-op visit. This needs to be referred immediately, and we will make the decision whether the flap should be lifted and the interface inflammation irrigated or if increasing steroids will be sufficient.

Figures 7 and 8 demonstrate how DLK can progress centrally and start affecting vision.

Permanent stromal scarring and vision loss can occur if DLK progresses without aggressive treatment (Figure 9).

Figure 7. Grade 2 DLK. Inflammation moving centrally. BCVA usually not reduced during this stage.

Figure 9. Grade 4 DLK. Permanent scarring.

Dry eyes are another potential complication after LASIK surgery. The best way to prevent dryness complications after surgery is to aggressively treat the dryness before surgery. Dry eyes can be treated with artificial tears, ointments, pulse doses of anti-inflammatories, Restasis, punctal plugs, and even bandage contact lenses (See: The Ocular Surface and Anterior Segment Surgery Tab).

Post-Op Care

General Rules:

  • No make-up for 1 week.
  • No water -related activities for 2 weeks.
  • Shields must be worn for 1 week while sleeping.
  • No rubbing of the eyes.
  • Follow drop instructions. See below.

Follow-up Regimen: 1 Day, 1 Week, 1 Month, 3 Months, 6 Months, 1 Year.

Day of Surgery:

We tell our patients that some hazy or foggy vision is also normal. Much like driving through morning fog. The haziness will improve throughout the day. We also tell them to expect 2-6 hours of some discomfort immediately following surgery. This discomfort can range from a mild, foreign body sensation to severe burning, watering, photophobia and stinging. However, no matter what type of discomfort the person has, it will typically only last 2-6 hours.

If their discomfort lasts longer than 6 hours or if it feels like there is a contact lens is balled up in their eye, we instruct them to call us immediately. We also instruct our patients not to sleep for 4-6 hours following their procedure. If they have documented dry eye we may have them use Erythromycin ophthalmic ointment at bedtime for the first week or so.

Drop Instructions

Pred/Gati: 1 drop qid x 1 week, bid x 1 week then D/C.

Non-preserved Artificial Tears: prn or as directed for the first three months. After that, it’s ok to use an artificial tear with a preservative

*All drops should be spaced out 10 minutes to avoid washing the first drops out.

LASIK Medication

1 Day Post-op:

Tests to Perform: visual acuity, refraction, slit lamp exam

The day following surgery is when most patients feel their vision has improved a lot. Most patients are not only comfortable, but drive to their 1 day post-op exam and go back to work this day. Your patient can have some dryness on this visit. If so, artificial tears and possibly night time ointment can be added at this stage. Of course, punctal plugs (temporary or permanent) are also an option. Diffuse lamellar keratitis (DLK) will sometimes be seen at this time. If so, notify us and then we can determine whether to increase steroids or consider a potential lift flap and interface rinse. If there are any flap striae, we should also be notified for a potential lift and smooth. Subconjunctival hemorrhages can be noted at this visit. We are not too concerned with this, as these will usually resolve within the first few weeks.

1 Week Post-op:

Tests to Perform: Visual acuity, refraction, slit lamp exam

This is when your patient will typically start tapering their drops. If your patient is not correctable to the preoperative visual acuity, and you can see some striae, it would be appropriate to have our surgeon smooth the flap. Evaluate the flap edge for epithelial ingrowth. This is another time DLK can be observed, and we should be notified.

1 Month Post-op:

Tests to Perform: Visual acuity, refraction, slit lamp exam, IOP (if applicable)

Patients sometimes complain of photophobia at this visit due to a rebound inflammation. This can usually be remedied with a steroid qid for 1 week.



3 Month Post-op:

Tests to Perform: Visual acuity, refraction (if considering enhancement), slit lamp exam, IOP (if applicable).

This is typically the earliest we will want to consider an enhancement. Although we would prefer to wait until the six month post-op exam. We also want to see a stable refraction before considering an enhancement. If we are considering an enhancement, then a cycloplegic exam, corneal thickness and topography must also be performed. Before considering an enhancement it’s also important to assess the tear film. In many situations, if a person has not achieved their target following LASIK, it is secondary to an underlying dry eye. If we are going to consider an enhancement, we want to ensure that there’s a minimum of 400 microns of total corneal tissue and at least 300 microns of untouched corneal tissue under the flap before we will consider re-lifting the flap, as well as the duration of time since their primary procedure. If we are uncomfortable with lifting the flap, we will perform a PRK enhancement instead of a LASIK enhancement.

6 Month Post-op:

Tests to Perform: visual acuity, refraction, slit lamp exam, IOP (if applicable)

If we are considering an enhancement, then a cycloplegic exam, corneal thickness and topography must also be performed. We also want to a stable refraction at this point before considering an enhancement.

1 Year Post-op:

Tests to Perform: visual acuity, refraction, slit lamp exam, IOP

If we are considering an enhancement, then a cycloplegic exam, corneal thickness and topography must also be performed. A stable refraction is also important for a successful enhancement.

Maximizing Patient Outcomes

There are three primary components to maximizing patient outcomes: Pre-operative examination, Intra-operative technology and experience and Post-operative management.

During the pre-operative examination it is important to not only get the appropriate measurements (Refraction, Topography, Corneal thickness, Wavefront, Cycloplegic refraction and Tear film assessment), but this is also an important time to set appropriate patient expectations and discuss the different types of LASIK technologies, e.g. Blade vs. Bladeless LASIK, Custom vs. Conventional. The pre-operative examination is also a critical time to prepare the ocular surface when appropriate with plugs and/or Restasis prior to surgery to maximize outcomes and minimize risk.

During surgery it’s important to have an experienced surgeon along with ALL the different technologies to allow a procedure to be matched to a patient’s surgical needs. It’s important to not only have Wavefront guided, but also Wavefront optimized technology. Eye tracking is also a must. Making flaps with a laser instead of a blade has been one of the biggest advances in LASIK technology.

During the post-operative period it’s important to be able to manage patient expectations and counsel them on the LASIK healing process as everybody has different healing tendencies. This is the time to “keep the pedal to the metal” on treating dry eye as well. The tears are critical in helping the patient feel comfortable, see clearly and heal predictably and accurately during this post-operative period.

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