Published in Refractive Surgery
The Intersection of Refractive Surgery and Therapeutics
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Therapeutic refractive surgery can be used to enhance other ocular therapies or to provide alternative treatment plans. Learn more about this growing field of ophthalmology and review supporting case studies.
Dr. Evan D. Schoenberg, MD is a highly respected corneal surgeon based out of Atlanta, Georgia, who specializes in restoring sight and improving patients' quality of life through therapeutic refractive surgery.
Eyes On Eyecare sat down with Dr. Schoenberg to discuss the intersection of refractive surgery and therapeutics and what residents should know about this specialty. What follows is the transcript of a verbal interview.
Schoenberg: When I say "therapeutic refractive surgery," I am referring to surgery that uses the traditional tools of a refractive surgeon to rehabilitate vision rather than for the primary purpose of eliminating glasses or contact lenses.
It's important to establish from the start that the mindset of both the surgeon and the patient needs to be very different than that of the classic case of a routine myopic patient who is getting LASIK to see well without glasses.
This is someone who comes in with a problem with their vision quality or a problem with their vision function, and we're using refractive surgery to address that problem. Not always to perfect it, but to make it better.
Schoenberg: There's a lot of overlap. There are a lot of situations where an alternative to therapeutic refractive surgery might be a well-fitting contact lens.
Still, that lens may not be the best choice for the patient based on other factors. A contact lens doesn't do them any good sitting on their bedside stand. They may not be able to master insertion and removal, may find that their work requirements or recreation goals aren't compatible with safe contact lens wear, or they may not be able to achieve good comfort with a lens. Those are situations where surgery can step in for those therapeutic purposes.
Schoenberg: The biggest category would be keratoconus and other corneal ectasias, as well as irregular astigmatism produced by both keratoconus and post-refractive corneal ectasia. These have been huge topics of interest in the cornea world and a major focus for optometrists specializing in scleral lenses, but it has not had as much appreciation among refractive surgeons.
This is unfortunate as it is fertile ground to make a big difference using the tools we've developed for our refractive practices. The top one that comes to mind is topography-guided photorefractive keratectomy (PRK), which allows us to take a topographic map and normalize it towards a better focusing system. It's similar to when a patient puts on a scleral contact lens, the difference being that this can work with them all the time.
The same can be said about irregular astigmatism from other sources. For example, we would treat localized changes and the cornea's focusing power for patients who have had previous ectasia keratitis and developed a scar or thinning. These things can be accounted for by using topography-guided PRK, and the results can be night and day for a patient who needs it, especially one who has been unable to have success with nonsurgical alternatives.
The other place where refractive surgery is used therapeutically is to remove corneal scars. It is here where a refractive surgeon may have a different mode of thinking than a traditional corneal surgeon. Often, our goal is to avoid a corneal transplant by using a laser to remove the scar or to reduce its density. If a patient's only alternative is a corneal transplant, they will not lose anything by trying.
Schoenberg: It's about the mindset as much as the approach.
If a patient has an irregular cornea where their best-corrected acuity is 20/80, and they get improved to 20/30 as a result of intervention, which in many cases is a very reasonable improvement for the patient who is hoping to have functional vision again, this is a celebration.
For the same patient, if they were expecting that it would be the same as the fellow eye or that they were going to fly fighter jets for the Air Force with that vision, they might be sorely disappointed. The same result with different expectations can feel very different.
When performing a topography-guided PRK for therapeutic purposes, you may not target the patient's full myopia because they're expecting to wear glasses. By doing so, you can reduce the intervention and reduce tissue removal by not treating the full prescription.
Therapeutic refractive surgery is not always about removing the need for contacts or glasses, but making those aids work. If you told a routine LASIK patient that our expectation after surgery is that they will still need to use glasses or contacts, that patient would go to a different surgeon.
However, if you tell a keratoconus patient who is nonfunctional without wearing a scleral lens that we're going to surgically reduce the aberrations, reduce their myopia and astigmatism, and get them a few lines better on the chart; that's a reasonable conversation.
It's also collaborative; in many cases, we first think of what nonsurgical tools we have, work closely with optometrists, and suggest their options to the patient.
A 24-year-old male with progressive keratoconus and contact lens intolerance, having tried soft lenses, RGPs, hybrid lenses, and scleral lenses, presented with severe frustrations. He stated that he couldn't get a driver's license due to his vision, preventing him from employment, though he sincerely wanted to work. His better-seeing eye had uncorrected acuity of 20/400 and best spectacle-corrected acuity of -0.25 -4.50 x 175 = 20/80.
Figure 1 outlines the patient's corneal topography with an axial curvature map and keratometry map.
Figure 2 shows the ablation pattern of the patient when treated with Epithelium-off crosslinking (Dresden protocol) using topography-guided PRK.
After 6 months, the patient reported he had been able to obtain a driver’s license and was now gainfully employed. Uncorrected acuity was now 20/70. Spectacle-corrected acuity was now -0.75 -1.25 x 45 = 20/40. This was stable at follow up 4 years later.
I highlight this case, rather than any number of cases with more “impressive” final visual acuity measures, because of the importance of setting expectations and recognizing that massive improvement in quality of life does not require a 20/20 result.
Figure 3 demonstrates the patient's corneal topography after receiving treatment.
Figure 4 features the clinical appearance of the patient's eye after receiving treatment.
A 41-year-old male with stable keratoconus, contact lens intolerance, and a very poor spectacle-corrected visual acuity of -4.00 +2.50 x 132 = 20/100 came in for treatment.
Figure 5 displays Pentacam imaging of the patient's cornea.
His goal was to achieve manageable vision in glasses, with a “stretch goal” of eliminating glasses if possible. We opted to place only the infratemporal Intacs segment. The postoperative result was -2.25 -3.50 x 123 = 20/30+2. Now that he could achieve functional vision in glasses, we proceeded to a toric ICL. The postoperative result was uncorrected acuity of 20/25 and best-corrected acuity of -0.25 -0.25 x 30 = 20/20-2.
It is common to see a one-line improvement in measured Snellen acuity when replacing a moderate or high myopic spectacle correction with intraocular correction. The myopic glasses act as a backwards telescope, creating image minification; once the correction is moved internally, the same source image has a larger retinal representation. The same effect occurs when moving from glasses to contact lenses.
This patient is a 62-year-old phakic male with a history of herpes simplex causing severe central corneal scarring. The scar depth was up to 220 microns from the surface (measured with anterior segment OCT) and associated with moderate stromal thinning. The best corrected acuity was 20/200, with no improvement with a scleral contact lens diagnostic trial.
Figure 6 highlights the patient's corneal scarring caused by herpes simplex.
Figure 7 features an anterior segment OCT image demonstrating anterior scarring and irregular epithelial hypertrophy overlying the scar.
Figure 8 illustrates the patient's corneal topography with an axial curvature map.
The treatment plan was to reduce the scar via a transepithelial PTK treatment, then to perform lens-based surgery to correct the induced refractive error. A double card treatment was -10.75 @ 7.0 mm optical zone followed immediately by -2.25 @ 8.0 mm optical zone and was calculated to ablate a total depth of 224 microns centrally, sufficient to reach the bottom of the scar.
Figure 9 is a clinical image of the patient's eye after receiving a transepithelial PTK treatment and lens-based surgery.
After 4 months following the laser treatment, the best-corrected acuity was +9.00 sph = 20/40.
This was followed by cataract surgery with a high power IOL. Starting 3 days before and continuing for 2 weeks after each of the PTK and cataract surgeries, we prescribed valacyclovir 1 g PO TID to reduce the risk of herpetic reactivation. The final result was +1.00 sph = 20/40, and the patient was very satisfied with the outcome.
Schoenberg: Topography-guided ablation, topography-guided PRK, Intacs, phototherapeutic keratectomy, and surprisingly, surgeries that seem like they would be less therapeutic and purely refractive can be included as well.
We can also use ICL to handle intolerable anisometropia or high refractive errors. If a patient can't wear a contact lens and they're a -16.00 myope, their whole world wearing those -16.00 glasses is of lower quality. Implanting a lens in this highly myopic person is more than just "now you can play tennis without glasses." It's life-changing. That's a therapeutic surgery.
While we approach each patient aiming at the bullseye, they're likely to be extremely satisfied even if you serve only to debulk rather than completely cure their nearsightedness. The same applies to using lens exchange techniques or piggyback IOL to treat hyperopia after surgery.
I saw a patient recently who was left hyperopic in one eye after cataract surgery. They were told their only option was to wear a contact lens because they couldn't tolerate the anisotropia between that eye and the fellow eye. The original surgeon hadn't offered them a lens exchange, as some time had passed since the initial surgery, and there was a lot of fibrosis to the capsule.
In addition to their poor vision, the patient we treated had been getting increasingly dry eyes, making contact lens tolerance difficult. It wasn't just a convenience factor—they were running out of the ability to tolerate that intervention.
Schoenberg: There is not any insurance coverage for topography-guided PRK. It has not yet reached a level of penetration that a code has been assigned for insurance to accept. As a result, it is an out-of-pocket procedure; however, that is rarely a barrier to motivated patients. In the rare case that someone needs it but can't afford it, I'm fortunate to work in a practice where I have enough flexibility to work with that patient.
That's very rare, though. In the vast majority of patients, when they say, "Wait, you can cure my blindness for a modest price?" they tend not to bat an eye. That being said, I believe that practices should offer financing options that provide better access to care. For example, many finance providers can offer 2 year no-interest plans.
In certain select cases, insurances provide coverage for the therapeutic laser side of PTK that reimburses at a much lower rate than at which surgeons typically perform their procedures. It can be worthwhile to address it as a combined therapeutic refractive approach and present it to the patient.
ICL doesn't have any coverage by insurance. IOL-based procedures, depending on the diagnosis, can be covered. For example, for the patient I discussed with the piggyback lens, their insurance came under the diagnosis of anisometropia, and we were therefore reimbursed.
Schoenberg: It's the intersection of performing an acceptable benefit-risk ratio regarding ocular health.
In an ectasia situation, it's common that I'm either combining the procedure with crosslinking or we're first performing crosslinking, then doing the therapeutic refractive laser once the cornea is fully healed and stabilized. This way, we feel more secure about treating a crosslinked cornea than a virgin (potentially unstable) cornea. If it's a very thin cornea and I'm worried we're going to thin it too much with laser, we might not treat it with that approach.
Then there's the aspect of patient expectations; you don't want to do a surgery where the patient's not on the same page as the surgeon. It's all about the conversation and making sure there's a good chance of visual success, which is where I will often have them do a contact lens trial as a diagnostic test to understand what changes to their topography are possible.
Schoenberg: These patients can call for more calculation and handholding, but I think the time invested is well worth it.
It's a very rewarding space in terms of visual benefit, and a huge number of patients could benefit from it but don't realize they have surgical options.