5th Annual Refractive Surgery Report
Here Come the Hyperopes

Investigational Procedures for the Hyperope

The success of laser correction for nearsightedness has many farsighted patients asking, 'Why not me?' Here's what you can tell them.

by John Sloat, O.D., King of Prussia, Pa.

With growing ranks of myopes seeking laser vision correction, legions of hyperopes are beginning to ask if they too can go under the laser to obtain clearer vision. Although the population of hyperopes isn't as large as that of myopes, patients with farsightedness are increasingly interested in lessening their dependence on glasses and contact lenses.

Optometrists play a critical role in imparting accurate information to hyperopic patients about the available options. You can help these patients moderate their expectations and hopes. For most, surgical correction of hyperopia—whether by laser-assisted in-situ keratomaleusis or the use of implantable devices—is a notion for the near future. 

Although none of these procedures is FDA-approved for treatment of hyperopia, they are in various stages of clinical investigation. Motivated patients with lower levels of hyperopia may be eligible for one or more of these procedures today. You need to know how to screen patients and explain the various corrective procedures. I'll discuss how to screen patients for LASIK and other corrective procedures, how you should go about your clinical work-up, and how each of the procedures works.

Patient Selection
Determining who is a good candidate for LASIK is much the same for hyperopes as with myopes. Among the key anatomical contraindications:

Keratoconus. Hyperopes with this corneal disorder are not good candidates for any laser procedure. Their thin corneas will not provide enough corneal thickness after laser ablation. Also, the procedure may precipitate corneal ectasia.

Previous herpetic eye disease. Some surgeons hesitate to ablate these corneas for fear that it will reactivate the virus. Others will do it, depending on the surgeon's skill and confidence, and the patient and the circumstances. We've done some of these in our clinic and they've turned out fine without any recurrence of herpes.

Active inflammation or infection. The key with these eyes is to treat first and make sure they are quiet before considering any surgery. With these patients, it's especially important to have their informed consent. You'll want to evaluate the patient's situation and carefully review it with him, but that doesn't mean he can't have the surgery.

Collagen vascular disease. There is a concern, especially with LASIK, that this could cause a corneal reaction that might lead to flap melt, although we haven't seen this.

Diabetes. A concern with diabetic patients is their thickened epithelial membrane. You must also make sure their blood sugar is stable and they have a stable refraction prior to surgery. Much depends on the patient, too. If the patient was diagnosed with diabetes 10 years ago and knows what his blood-sugar levels have been, and he's been under control, then this person may be a good candidate for surgery.

If the patient has only known he's had diabetes for six months or a year, and does not yet have his blood-sugars under control, that person could have subtle refractive changes that could affect the outcome. You want to know that a diabetic patient has a stable refraction before going ahead with LASIK or any other cornea-altering procedure.

Severe dry eye. Again, many surgeons differ on whether this is a true contraindication. Some say it is, others will talk to the patient about it and explain that sometimes dry eye can worsen after surgery. They'll educate their patients and treat the dry eye aggressively. Always perform a Shirmer's or Zone Quick test on these patients, and evaluate their tear breakup times and rose Bengal staining.

Patient Expectations
Managing patient expectations is as critical in the patient selection process as the physiological factors. It's important that you flesh out what each patient is looking for. We have our patients fill out a form that basically says, "I want to have refractive surgery because ..." We let the patient fill in the blank. We review this before sitting down with patient. This will give you much insight into what the patient really wants.

If the patient says, "I don't want to use glasses as much," this indicates his expectations make him a good candidate for the procedure. On the other hand, if the patient says, "I want to see 20/20 all the time without glasses far and near," chances are, he'll be disappointed with any surgery that's less than perfect.

Not that you have to write off the latter type of patient. Of course, you'll need to do some counseling. When you look at the preoperative care, 90 percent is spent on counseling. Sometimes you have to be blunt with these patients: "Look, you're starting with such a high prescription, you're not being very realistic about the surgery." Of course, with hyperopes this is more difficult now because of the success of LASIK for myopia. Most people know someone who has had that procedure and is doing well. That only raises the expectations of hyperopes. We're just not at the point with hyperopic LASIK that we're at with the myopic procedure.

It's also challenging to manage the expectations of presbyopes who are already wearing bifocals. Often they'll ask, "Let's do it so I don't need any glasses." For those with low levels of hyperopia, +1.00D to +2.00D, you can shoot for a –1.00D or –2.00D for monovision. We will take a monovision approach with them. However, if they're starting off with +5.00D, we just don't have that room to work with to get them down as far where they want to be for monovision. 

We usually recommend monovision LASIK only to patients who have experienced this approach with contact lenses. That's critical, because some patients cannot adapt to monovision, and you want to know that before you do a surgical procedure on them. In a few cases we've done modified monovision, leaving about -0.50D of nearsightedness. It's been mild enough so the difference between the eyes doesn't pose an adaptation problem for the patient.

Since we tend to see amblyopia in either or both eyes more often with hyperopes than myopes, this is an additional consideration when screening the former for LASIK. If one eye is 20/20 and the other 20/30, we'll tell them the best-case scenario is that this difference between the eyes will still exist, except without glasses.

I just can't stress enough how important it is to sit down and talk with the patient and find out what he wants to get out of the surgery. It sounds odd, but most of the time we spend with the patient goes into the pre-op.

The Clinical Work-up
Your pre-op exam of the hyperopic refractive surgery candidate varies little from that of the myope. Of course, you must obtain corrected and uncorrected visual acuities. Bear in mind that young hyperopes might be able to accommodate well, say +1.00D to +1.25D, sometimes +1.50D. They tend to be 20/20 uncorrected through accommodation. We won't operate on these patients because they are 20/20 uncorrected and we can't improve their vision that much. We usually tell them to enjoy their vision now, but at some point their hyperopia will catch up with them and their visual acuity will decrease. At that point they would be candidates for surgery.

Other components of the preoperative work-up for hyperopes are:

    • Manifest and cycloplegic refraction.

    • Keratom-etry and corneal topography.

    • If considering laser or ring, corneal thickness measurement.

    • Dilated fundus exam.

    • Tear testing—Zone Quick or Shirmer's test.

    • Pupil testing—in bright and dim illumination, to assess if they're at greater risk for glare and night haloes.

LASIK for Hyperopes
This procedure for +1.00D to +5.00D of hyperopia is in an FDA-approved investigation. From a physiological perspective, it's similar to myopic LASIK, with a couple key exceptions. There is little or no ablation centrally. Rather, the ablation is concentrated toward the periphery of the stromal bed. Where the goal in treating myopia is to leave a bowl-like shape, in hyperopia the goal is to create more of a hill. Post-op comanagement of hyperopic LASIK is similar to that of myopia.

A few years ago we tended to see a higher incidence of epithelial cells in hyperopic interfaces vs. myopic ones. However, with the masking devices surgeons now use, the incidence these days is about the same.

How you treat interface cells depends on the presentation. If they appear on the edge of the flap and cause no astigmatism changes, just monitor them. Watch for cell buildup that can cause flap melt. Monitor striae or wrinkles in the flap as well. If they're peripheral and the patient is asymptomatic, determine if it's worth trying to get them out. Refer cases of central of visually significant striae back to the surgeon for treatment as soon as possible. Don't sit on these patients; the longer you wait, the harder it is to remove straie. Sometimes what looks bad to the doctor isn't so bad for the patient. Of course, when any of these signs appears, we strongly recommend you confer with the surgeon on how to manage it.

There are some visual complications unique to hyperopic LASIK. Over- or undercorrection takes a little longer to stabilize in hyperopes than in myopes. Usually we see slight overcorrection, and this can show a little regression back toward hyperopia over time. This is where your pre-op counseling is valuable. Advising the patient of fluctuations in visual acuity before surgery can save those hectic phone calls afterward.

Another complication of hyperopic LASIK: glare or decreased night vision. Earlier, this seemed to occur more in hyperopes than in myopes; now it's at about same level—no more than 1-2 percent of patients. There's an ongoing debate on whether pupil size or corneal shape contributes to this phenomenon. A study published in the Journal of Refractive Surgery found little correlation. For some hyperopes it probably is related to the pupils, while for others it may have to do with the shape of cornea. For others it may be a combination of the two. In any event, it typically resolves within two to three months. In rare cases it can be permanent.

Perioperative flap complications are also an issue, but no more so in hyperopic LASIK than in myopic. Another complication is irregular astigmatism. This is uncommon, but you may encounter it any time after surgery. The cornea looks fine, but the K-readings may be distorted. If you have any doubt, do topography. There are three approaches to handling irregular astigmatism: let it heal; prescribe an RGP to sharpen the vision; or phototherapeutic keratectomy (PTK).

We work with the Biomask gel, but other surgeons use different coupling solutions. The idea is to apply the solution to the cornea, overlay the RGP and let it cool. In theory this should give the cornea the same curvature as the lens after ablating the gel with the excimer laser.

Other Options
PRK. Again, this is essentially the same procedure as that used for myopes. One difference is in the mechanics: the surgeon uses the scanning laser in the hyperopic mode or applies a masking agent to direct more ablation peripherally vs. centrally.

Recovery is fairly typical of PRK. The patient takes drops for one to three months, wears a bandage contact lens and waits two to five days for re-epitheliazation to occur. Of course, PRK is done monocularly, and vision takes a little longer than LASIK to stabilize, typically three to six months. The patient has the other eye done well before that, but from a counseling standpoint, you may have to do more hand-holding with PRK than with LASIK.

Complications are no different than those that occur in myopes—haze and over- or undercorrection. Doctors differ in how they handle these problems. For overcorrected myopes, some doctors use steroids to push the refraction and slow down healing. In hyperopes who are overcorrected and seem to be staying that way, doctors may use steroids to nudge the refraction back toward emmetropia.

As with any surgical patient, you need to be vigilant for infections. Irregular astigmatism is a possibility, as it is in LASIK patients. The management is the same.

LTK. Laser-thermal keratoplasty is another option. Sunrise Technologies makes the holmium laser for this procedure, which has been proven safe. However, the FDA Advisory Committee has yet to issue an approval letter for LTK because its members had a question with the long-term drift and correction.

The theory is to place spots around the periphery of the cornea. This causes contraction of fibrils, steepening the cornea. Because this procedure is safe, it's a good option for +2.50D of hyperopia or below.

With hyperopes, as with myopes, properly screening and counseling about the surgery is 90 percent of ensuring a satisfactory outcome. From a technology standpoint, we really aren't as advanced with treating hyperopia as we are with myopia. Some technologies look terrific at this point. But we're taking a cautious approach with hyperopes. We'll tell them that, yes, they may be candidates numerically, but the technology might not be quite ready for them.

Dr. Sloat is an associate with Kremer Laser Eye Center near Philadelphia.

Investigational Procedures for the Hyperope

Here's a look at some procedures that may hold out hope for correcting hyperopia.

Corneal implants. KeraVision makes Intacs for myopia and is studying implants for hyperopia.

LASIK for high hyperopia. LaserSight will be investigating treatments of up to +8.00D of hyperopia.

Lens implants. The Artisan lens by Ophtec USA is an implantable phakic lens that's investigational at this point. Lens implants for hyperopia have similar risk profiles as those for cataract: potential for anterior capsule rupture or infection, endothelial cell loss, glaucoma, cataract formation and chronic iritis and potential endophtalmitis.

Implantation of the Artisan lens requires an A-scan reading to determine axial length measurements and, more importantly, anterior chamber depth. The problem with hyperopes is that their chambers are shallow to begin with; many do not have adequate chamber depth to accommodate the implant.

While this lens does offer spherical correction, it cannot treat cylinder at this point. With the lens, you need less than 2.25D of cylinder.

Starr Surgical is also investigating an Implantable Contact Lens that goes in front of the natural crystalline lens. It's not an anterior chamber lens. The complication profile resembles that of the Artisan lens.

Clear lens extraction and implant. This is basically like cataract extraction and lens implantation, except that there's no cataract and the lens is clear. The risk profile is the same as with cataract surgery. Retinal detachment is always a concern with lens removal and implantation, but is more common if the patient is myopic vs. hyperopic.

For aphakes with high-plus powers, a secondary lens can be done—either an anterior chamber lens or a sutured posterior chamber lens.

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