Refractive lensectomy challenges laser iridotomy as management for narrow angles
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Welcome to another edition of CEDARS/ASPENS Debates. CEDARS/ASPENS is a society of cornea, cataract and refractive surgery specialists, here to discuss some of the latest hot topics in ophthalmology.
Peripheral iridotomy placement for the management of narrow angles and angle closure has long been thought of as the standard of care. Over the years, many have advocated another treatment, lens extraction, even if no cataract is present. This month, Gregory D. Parkhurst, MD, FACS, and Nathan M. Radcliffe, MD, discuss their approaches to this condition. We hope you enjoy the discussion.
Kenneth A. Beckman, MD, FACS
OSN CEDARS/ASPENS Debates Editor
Refractive lensectomy for narrow angles in glaucoma
When we see a patient with narrow angles, we can expect them often to be hyperopic. Having a shorter eye usually means that their anterior chamber and angles are overcrowded as well.
Such patients in their late 40s or 50s who become presbyopic usually have hyperopia of at least 2 D to 3 D, but sometimes 5 D to 6 D or more when they present seeking laser vision correction. For this patient population, laser refractive surgery has limitations.
In the U.S., we do not have a multifocal variant of laser vision correction approved, only the option to correct for distance vision or to perform a blended vision LASIK procedure, in which one eye is corrected more for near. The problem is that we often bump up against the limits of how much hyperopic ablation we want to perform in that setting. So, laser vision correction is often not ideal to treat patients seeking refractive surgery in that demographic.
Is there another option for fixing their refractive error? There is. Refractive lens exchange is a great solution for hyperopia. Especially in patients with narrow angles. We can deepen the angle, lower the IOP and eliminate the refractive error for distance, middle and near if we use a trifocal IOL.
For patients with the same clinical conditions who are referred for laser peripheral iridotomy (LPI) but not for refractive surgery, I have a similar thought. I often consider clear lens extraction as a better solution than LPI because the clinical scenarios are the same. The difference is only the reason for the referral or presentation of the patient.
In 2016, Azuara-Blanco and colleagues published the EAGLE study, a prospective multicenter clinical study specifically looking at the clinical efficacy and safety of performing early clear lens extraction in the setting of patients with just narrow angles and elevated IOP and then a second subset of patients who actually have narrow-angle glaucoma showing nerve damage. Patients underwent either clear lens extraction or LPI. It turns out that patients who underwent clear lens extraction had both lower IOP and were on fewer medications than patients in the iridotomy group. Furthermore, patients in the clear lens extraction group had less glaucomatous vision loss compared with those in the iridotomy group who were also being treated for narrow-angle glaucoma.
Another primary endpoint in the EAGLE study looked at improvement in quality of life as measured by the EQ-5D questionnaire. The clear lens extraction group had an improvement in their EQ-5D scores, whereas patients in the LPI group had a reduction.
And so, this well-done, well-designed, well-run clinical trial performed on three continents with more than 400 subjects demonstrates that early clear lens extraction should be considered as an alternative to doing LPI.
From a surgical perspective, many patients who undergo LPI at some later point are going to need cataract surgery. By performing early lens extraction, the patient is subjected to intraocular surgery at an earlier age, and there is some potential risk involved. However, that risk is low. In patients who undergo LPI and later cataract surgery, especially when the iridotomy is placed temporally, cataract surgery can be more complicated and difficult to perform. The patients often do not dilate well, sometimes have synechiae or the iris may prolapse during surgery.
Those are just a few reasons why I believe clear lensectomy is often a better way to treat narrow angles than LPI. You fix the IOP problem, you fix the angle, and most noticeably to the patient, you eliminate the refractive error and help them see better.
Who wants to go around wearing Coke bottle glasses anyway?
- Reference:
- Azuara-Blanco A, et al. Lancet. 2016;doi:10.1016/S0140-6736(16)30956-4.
- For more information:
- Gregory D. Parkhurst, MD, FACS, can be reached at Parkhurst NuVision, 9725 Datapoint Drive, Suite 106, San Antonio, TX 78229; email: gregory.parkhurst@gmail.com.
Laser iridotomy for narrow angles in glaucoma
What iridotomies do is prevent fluid buildup behind the iris in the event that the fluid buildup is pushing the angle closed. In cases of narrow angles due to fluid buildup and not due to cataract or abnormal anatomy, we see a good effect from laser iridotomy.
The best evidence we have that laser iridotomy works comes from the Zhongshan Angle Closure Prevention trial, which showed risk for developing angle closure or angle-closure glaucoma was reduced by half in iridotomy-treated eyes compared with non-treated eyes.
In the study of 889 patients with suspect bilateral primary angle closure randomized to either a laser or observation group, angle closure developed in statistically significantly fewer treated eyes than untreated eyes (P = .024). Angle-closure glaucoma, characterized by high IOP and scarring, developed in only 19 treated eyes compared with 36 untreated eyes (P = .0041).
In both cases, the rate of people running into trouble from this problem is relatively small.
The problem with citing the EAGLE study for this debate is that, even though the lens extraction group did well, participants in the study had pressure greater than 30 mm Hg, a damaged optic nerve and no cataract. In eyes with narrow angles, the pressure is not elevated yet. This is the time when laser could be beneficial, before there is damage.
There is a caveat that iridotomy in patients with dark-pigmented irises that are thick may be more traumatic than in lighter, thinner irises. For those patients, cataract extraction may be the better choice.
One of the reasons to choose laser iridotomy is because it is a procedure that can be done moments after disease is diagnosed in the office. Although it could be performed at a surgery center, in the best case, the physician could diagnose the condition, discuss and consent with the patient, and perform the laser procedure. The whole process can be done on the order of minutes rather than over multiple visits.
In fact, both eyes could be treated on the same day if the patient needs to travel, for example. There are no restrictions after the procedure, there is zero risk of infection, and there is only a small risk of resultant linear dysphotopsia (laser temporally or nasally, not superiorly, to significantly reduce this). There is an even smaller risk of inflammation lasting not more than a day or two, and that is almost always treatable with eye drops.
While it may be true that people with narrow angles are often farsighted, there are also a lot of narrow-angle patients who are emmetropes with perfect distance vision, which means a clear lensectomy will not improve on spectacle requirements in someone who does not need glasses to begin with.
The pros of iridotomy in many patients is that they see perfectly fine and do not need refractive correction. They are diagnosed with this sort of surprise problem. And you can do the laser and have them out of the office in 5 minutes, going back to live their life. It is minimally invasive.
The cons of cataract extraction are that there can be some pretty severe rare complications: infection, inflammation, macular edema. The refractive errors can be missed, which is more likely in eyes that already have some anatomical abnormalities. And there is a significant quality of life disruption and patient time commitment that needs to be factored in.
- References:
- He M, et al. Lancet. 2019;doi:10.1016/S0140-6736(18)32607-2.
- Yan YJ, et al. Invest Ophthalmol Vis Sci. 2014;doi:10.1167/iovs.14-14426.
- For more information:
- Nathan M. Radcliffe, MD, can be reached at New York Eye Surgery Center, 1101 Pelham Parkway North, Bronx, NY 10469; email: drradcliffe@gmail.com.
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