MIGS, premium IOLs, VMT propel optometric care to the next level
More optometrists are managing and comanaging glaucoma, cataract and retina patients, and advances in the areas of minimally invasive glaucoma surgery, premium IOLs and vitreomacular traction diagnosis are rapidly developing.
Minimally invasive glaucoma surgery
The iStent (Glaukos) was approved by the FDA for use in cataract surgery in 2012.
“The single trabecular bypass element was initially designed in such a way that the procedure to place it was slightly more complex, and I think there was a lack of uptake on the device as a result,” J. James Thimons, OD, of Ophthalmic Consultants of Connecticut, told Primary Care Optometry News. “It was looked at as more of a glaucoma specialty device, but the goal was to make it available to any surgeon who had glaucoma patients.”
A prospective, randomized study by Katz and colleagues showed sustained efficacy through 18 months after single or multiple iStents were used as the sole therapy in patients with open-angle glaucoma.
The FDA approved the new iStent Inject (Glaukos) in June.
Thimons said that this newer device corrects some of the initial challenges, such as manipulation and manual dexterity.
“It’s a very simple, straight cross chamber insert, and it looks like a punctal plug,” he said.
The device provides better IOP control, and the placement is less challenging, Thimons said.
“I anticipate that the iStent Inject will become a very successful device as a result of resolving the mechanical and placement issues, and implanting two stents at the same time will result in better outcomes with less complexity,” he said.
The iStent Inject is effective for patients taking one glaucoma medication, Thimons said.
“Unfortunately, it is not approved for use outside of cataract surgery, and there is a large block of patients who do not qualify for reimbursement, as they have already had cataract surgery,” he said.
In the iStent Inject clinical trial, 387 subjects were randomized to iStent Inject in combination with cataract surgery, and 118 subjects were randomized to cataract surgery only.
At 24 months, 75.3% of the iStent Inject cohort achieved a 20% or greater reduction in unmedicated IOP, compared to 61.9% for the cataract-only cohort. At 24 months, the mean unmedicated IOP reduction was 6.9 mm Hg for the iStent inject cohort, compared to 5.4 mm Hg for the cataract-only cohort.
In 2016 the FDA approved the Xen Gel Stent (Allergan), a transscleral device that can be used during cataract surgery or outside of it.
“The initial viewpoint that I’m getting is that it’s for more advanced cases, for the patient on two or more medications,” Thimons said.
The device is effective, but there are slightly more complications with insertion than with the iStent, such as bleeding at time of the procedure, he added.
The device lowers pressure considerably, about 40% from baseline according to the major trials, Thimons said.
He noted a need to re-needle or recreate the bleb more frequently than with trabeculectomy, but much less hypotony and macular pucker and fewer choroidal effusions.
Depending on surgeon experience, Thimons estimated that one of every seven procedures may need a revision.
In clinical trials, 76.3% of subjects achieved at least a 20% mean diurnal IOP reduction on the same or fewer number of medications versus baseline. The mean diurnal IOP reduction from baseline was 6.4 mm Hg. Further, Xen reduced mean IOP by at least 25% in 80.8% of eyes.
Thimons noted that because Xen operates with a different mechanism, it could be used in conjunction with an iStent to lower IOP from a different perspective.
Another trabecular bypassing system, Hydrus (Ivantis), was approved by the FDA in August.
The iStent and Hydrus lower IOP in a similar manner, Thimons said.
In the HORIZON trial, which involved 556 mild to moderate glaucoma patients undergoing cataract surgery, 77.2% of patients in the Hydrus Microstent group achieved a statistically significant decrease at 24 months postoperative, compared to 57.8% in the cataract surgery-alone group.
Alcon’s Cypass is a supraciliary device effective for moderate glaucoma.
The 2-year clinical data showed great promise, according to Thimons. However, the 5-year data showed a change in endothelial cell count that was statistically significant, causing the company to initiate a worldwide product recall.
“It seems to be an anatomic issue relative to device placement – how deep the device was placed versus how shallow,” Thimons said. “We are currently recommending endothelial cell counts at a 6-month cycle along with gonioscopy. If a patient shows endothelial count change, and the device shows more than one ring visible, the current guidelines from the American Society of Cataract and Refractive Surgery (ASCRS) recommend truncation as the first step.”
He anticipates a significant number of patients will be unaffected.
“This will likely put a dimmer switch on the MIGS process,” Thimons said. “I suspect doctors will be a little more conservative with how they approach implantation of these devices until each of the companies shows little or no endothelial cell count damage over time.”
In eyes with none or one ring of the CyPass device visible in the anterior chamber by gonioscopy, without clear evidence of corneal decompensation, the consensus was that no action other than clinical monitoring is recommended, according to the Preliminary ASCRS CyPass Withdrawal Consensus Statement.
In eyes with two or three rings, there is a greater risk of corneal endothelial cell loss. “However not all eyes in this category will experience clinically meaningful endothelial cell loss. Without clinically significant evidence of corneal decompensation, no action other than monitoring is indicated,” the statement reads.
Furthermore, “gonioscopy should be performed on patients with an indwelling CyPass device with attention to device position – the presence or absence of contact between the corneal endothelium and the CyPass device, the position of the device lumen anterior to Schwalbe’s line and the number of retention rings visible in the anterior chamber,” according to the statement.
Comanaging patients after MIGS
During the first 3 months of the MIGS postoperative period, IOP spikes need to be managed with topical glaucoma medication, oral medication or – if optometrists are comfortable with it – anterior decompression, Justin Schweitzer, OD, FAAO, who practices at Vance Thompson Vision in South Dakota, told PCON.
Patients need to be educated that their pressure can fluctuate up and down because they just had surgery, “and these are glaucoma patients already prone to have IOP issues,” Schweitzer added.
Hypotony due to MIGS is different than with a tube shunt or trabeculotomy, he said.
“With MIGS, you don’t usually see a flat anterior chamber and you don’t usually see large choroidal effusions. There is a lot more waiting and watching with MIGS hypotony,” Schweitzer said.
Before surgery, he educates patients that there is a chance for blood in the eye and clouded vision. He said a little hyphema inside the eye is not a big problem, but if it fills the entire anterior chamber, the patient should be sent back to the surgeon.
Also, 3 months postoperatively Schweitzer recommends re-establishing baseline testing. Patients will need new visual fields, new OCTs and a new target range of IOPs. He also recommends looking at the device with a gonioscopy mirror in the postoperative period to make sure that it is placed properly and a little tuft of iris is not plugging the stent.
New therapeutic delivery systems for glaucoma
Thimons is excited about potential new delivery systems in this space.
Bimatoprost SR (Alcon) is an injectable pellet that goes into the anterior chamber and slowly dissolves over an extended period. Once the pellet dissolves, another one is placed.
Bimatoprost ring (Allergan) is currently in clinical trials. The ring’s base allows it to slowly elute from its position in the superior and inferior fornix.
“I like the concept, but I don’t know what patients will think; you can see a little bit of it when it’s in the eye,” Thimons said.
Eye Dose (Glaukos) is an insert that contains travoprost. Phase 2 clinical trials were recently completed.
“I anticipate that this product and Allergan’s will end up with good results. They have very good IOP responses; they are both completely reversible and short term,” Thimons added.
Mati Therapeutics is working on a punctal plug system that features one closed end and one open end with a small flute at the top, where the drug is placed to elute evenly.
“The Holy Grail is how to get glaucoma under this umbrella, because it’s a lifelong treatment,” Thimons said. “There are already codes and billable diagnostic entities to allow it to take place. If you can envision a platform where you have basic structural success, you can place any kind of drug in it. There are many options. It’s fascinating and removes the patient from the compliance problem.”
Advances in the area of premium IOLs are also occurring rapidly.
“There’s now an increased market share to get optometrists and ophthalmologists back into the game and excited about advanced IOLs,” Josh Johnston, OD, FAAO, of Georgia Eye Partners, said in an interview.
Alcon’s AcrySof IQ Restor Multifocal IOL features an apodized-diffractive optical structure, meaning it is designed using gradual step heights toward the periphery of the diffractive zone, Johnston wrote in a recent blog for PCON.
Tecnis Multifocal IOL (Johnson & Johnson Vision) has a full-diffractive profile on the posterior surface of the optic. The relief height of the diffractive rings leads to an equal light distribution to distance and near, regardless of pupil size or add power, he wrote.
Tecnis Symfony is an extended-depth-of-focus (EDOF) IOL. While it also uses diffractive technology, it does not split the light into two focal points. “The implant’s proprietary echelette design produces a pattern of light diffraction that elongates the focus,” Johnston explained.
Bausch + Lomb’s Crystalens AO is an accommodating implant that requires less neuroadaptation compared to multifocals and is less sensitive to lens misalignment and pupil size, he continued.
“The implant provides superior intermediate vision and quality of vision over a more natural range by using 100% of light at all times,” he said.
RxSight’s Light Adjustable Lens IOL was approved by the FDA at the end of 2017. The lens is unique in that it can be adjusted postoperatively to improve uncorrected visual acuity, he said.
FDA approval was based on results from a study comparing the Light Adjustable Lens to a commercially available monofocal lens in 600 patients with pre-existing astigmatism. Patients receiving the Light Adjustable Lens followed by light treatment with the Light Delivery Device achieved uncorrected visual acuity of 20/20 or better at 6 months postoperatively at approximately twice the rate of patients receiving a monofocal lens.
“We now have lenses from Alcon and Johnson & Johnson Vision that can give distant, intermediate and near vision, trying to mimic the functional vision we were born with,” Johnston told PCON. “The newer IOLs have more of a commitment to distance vision, less loss of energy, less glare and halos, and fewer side effects.”
EDOF IOLs can lead to less chair time, fewer unhappy patients and better outcomes with customized vision based on demand, Johnston added. In general, the older-generation multifocals have a different approach for comanaging, with more hand-holding, more chair time and increased customer service.
Today’s IOLs are more customizable, whether the patient desires near or distance dominance, and chair time is reduced, Johnston said. Fear of explantation holds surgeons back, and price is generally what holds patients back. However, in the future, IOLs might be easier to exchange when there is a problem, he said.
Omega Ophthalmics is a company developing a refractive capsule that can be implanted in the capsular bag at the time of surgery, Johnston continued.
“This capsule allows surgeons to easily implant new technologies, explant IOLs and exchange IOLs based on what technology is in favor at the time,” he said. “This platform promises to allow patients that can’t adapt to advanced technology IOLs to have a less invasive IOL exchange compared to current methods used today. That’s the future: Take them in and out as much as we need to, as much as the technology allows.”
Surgeons can correct corneal astigmatism by implanting toric IOLs, creating laser arcuate incisions or performing limbal-relaxing incisions, he added.
“To be able to manage even low levels of cylinder at the time of cataract surgery is a must for today’s cataract surgeons,” Johnston said in his blog.
The industry’s understanding of vitreomacular adhesion (VMA)/vitreomacular traction (VMT) has vastly improved in recent years, according to Sherrol Reynolds, OD, FAAO, an associate professor at Nova Southeastern University and a clinical attending in the diabetes and macular clinic.
Optometrists can diagnose and monitor VMA and VMT with OCT.
“We now know that in patients with pathologic myopia, VMT can result in myopic maculopathy (myopic macular schisis) that can compromise vision,” Reynolds told PCON, “and VMT may reduce the effectiveness of anti-VEGF therapy in conditions such as diabetic macular edema.”
VMA becomes VMT when there is persistent or chronic traction causing distortion of the macula, Reynolds said. VMA patients need to be educated on the signs of VMT (visual blur, photopsia, micropsia or metamorphopsia), use an Amsler grid daily and be monitored every 3 months with serial OCTs.
“What really drives surgeons to do surgery on any vitreomacular traction is symptoms over structure, Diana L. Shechtman, OD, FAAO, Retina Macula Specialists of Miami, said in an interview. “Are they bothered by metamorphopsia? Are they aware of decreased vision?”
She added that surgeons have a lower threshold to treat if the other eye had a macular hole in the past. If a macular hole is present in one eye and VMT in one eye, there is a 10% to 15% chance the patient will have a macular hole in the other eye as well, she said.
VMT with mild symptoms and clinical features (cystoid changes) can be monitored with OCT every 3 months to see if spontaneous resolution occurs, Reynolds said.
“Studies have found that VMT resolves spontaneously in up to 53% of patients in about 15 to 18 months,” she said.
Prognostic features, such as focal (up to 1,500 µm) or V-shaped VMT have been reported to be associated with impending full thickness macular hole (FTMH) and cystoid macular edema (CME), while broad (greater than 1,500 µm) or J-shaped VMTs are associated with epiretinal membrane (ERM), diffuse retinal thickening and less FTMH, Reynolds said.
Patients with VMT and worsening vision and symptoms that may impact their quality of life or exacerbate clinical findings such as ERM or lamellar or FTMH should be referred to a retinal specialist, Reynolds said.
Shechtman agreed, adding, however, that because the condition cannot be detected without OCT evaluation, patients with VMT are commonly undiagnosed.
Reynolds said there are currently no published consensus guidelines for VMT management. The general recommendation is observation every 2 to 3 months and daily Amsler grid to check for spontaneous resolution.
In the case of a VMT patient with a clinically significant cataract, the retinal specialist needs to evaluate and clear the patient before cataract surgery, according to Reynolds. The vitreous can shift forward or exacerbate VMT post-cataract surgery, and the patient is at risk for complications such as CME.
“This can be addressed with combined vitrectomy-cataract surgery to improve visual outcome,” she said.
“The presence of a cataract may change the dynamics of VMT and may remove the need for doing a vitrectomy,” Shechtman added.
Reynolds tells patients with VMT/ERM that the need for surgical intervention, an ERM peel, depends on the severity of symptoms and its impact on their daily tasks such as driving or reading.
“If their vision is less than 20/40 or they have symptoms (like metamorphopsia), it may be time to get a consult from the retinal specialist, as earlier intervention may result in better long-term visual acuity recovery,” Shechtman said.
Jetrea (ocriplasmin injection, ThromboGenics) is indicated for symptomatic VMA; however, Reynolds said that cost (versus vitrectomy) and reported adverse effects (including severe vision loss, vitreous floaters, central scotoma, color vision anomaly and disruption of the photoreceptor layer) may limit its use.
It can be an effective nonsurgical alternative in select patients symptomatic for VMT and FTMH (no more than 400 µm), she noted.
- Allergan website. Clinical effectiveness of Xen. https://hcp.xengelstent.com/clinical-efficacy. Accessed October 22, 2018.
- Glaukos press release. IDE pivotal trial results for Glaukos’ iStent Inject show significant reductions in unmedicated IOP in glaucoma subjects undergoing cataract surgery. http://investors.glaukos.com/investors/press-releases/press-release-details/2018/IDE-Pivotal-Trial-Results-for-Glaukos-iStent-inject-Show-Significant-Reductions-in-Unmedicated-IOP-in-Glaucoma-Subjects-Undergoing-Cataract-Surgery/default.aspx. April 14, 2018
- Ivantis press release. Ivantis announces FDA approval for its innovative Hydrus Microstent device for minimally invasive glaucoma surgery (MIGS) https://www.prnewswire.com/news-releases/ivantis-announces-fda-approval-for-its-innovative-hydrus-microstent-device-for-minimally-invasive-glaucoma-surgery-migs-300695920.html. August 13, 2018.
- Johnston J. BLOG: Astigmatism correction essential to 20/happy cataract outcomes. https://www.healio.com/optometry/cataract-surgery/news/blogs/%7B11a9f70d-935a-4b39-9e87-f7484b2d928f%7D/josh-johnston-od-faao/blog-astigmatism-correction-essential-to-20happy-cataract-outcomes. Posted May 14, 2018
- Johnston J. BLOG: Why ODs should comanage cataract surgery. https://www.healio.com/optometry/comanagement/news/blogs/%7B86f70f7a-c18a-430f-8fcc-1951da377748%7D/josh-johnston-od-faao/blog-why-ods-should-comanage-cataract-surgery. Posted April 12, 2018.
- Katz LJ, et al. Clin Ophthalmol. 2015;doi:10.2147/OPTH.S96695.
- Rx Sight press release. FDA approves RxSight’s Light Adjustable Lens, first IOL to enable refractive correction after cataract surgery https://www.rxsight.com/media/1002/pr_2017_nov_22_rxsight.pdf. November 22, 2017.
- For more information:
- Josh Johnston, OD, FAAO, is clinical and residency director at Georgia Eye Partners in Atlanta and a blogger for PCON. He can be reached at: email@example.com.
- Sherrol Reynolds, OD, FAAO, is an associate professor at Nova Southeastern University, a clinical attending in the diabetes and macular clinic and a member of the PCON Editorial Board. She can be reached at: firstname.lastname@example.org.
- Justin Schweitzer, OD, FAAO, practices at Vance Thompson Vision in Sioux Falls, S.D., and is a member of the PCON Editorial Board. He can be reached at: email@example.com.
- Diana L. Shechtman, OD, FAAO, is the consultative optometric physician at Retina Macula Specialists of Miami and a member of the PCON Editorial Board. She can be reached at: firstname.lastname@example.org.
- J. James Thimons, OD, practices at Ophthalmic Consultants of Connecticut in Fairfield and is a member of the PCON Editorial Board. He can be reached at: email@example.com.
Disclosures: Johnston reports he is a consultant to Akorn, Alcon, Allergan, Avellino, Bio-Tissue, Bruder, Kayla Pharmaceuticals, Johnson & Johnson Vision, Sun Pharma and Shire. Reynolds reports no relevant financial disclosures. Schweitzer reports he is a consultant and lecturer for Alcon, Allergan and Glaukos. Shechtman reports she has received lecture honoraria or serves on the advisory boards or speakers’ bureaus of Alcon, Allergan, Bausch + Lomb, Essilor, Optos, ScienceBased Health, Zeavision and Carl Zeiss Meditec. Thimons reports no relevant financial disclosures.