EyeWorld/ASCRS reporting live from Cornea Subspecialty Day and Glaucoma Subspecialty Day at AAO in San Francisco, Saturday, October 12, 2019
Subspecialty programming continued on Saturday, with sessions dedicated to cornea, glaucoma, and more.
The theme of this year’s Cornea Subspecialty Day was ‘Keeping Disease at Bay,’ and the first section explored topics in ectasia. Michael Belin, MD, Marana, Arizona, discussed imaging keratoconus.
Kmax has been used for a number of years, but it’s a limited parameter because it only measures one point, he said. The “holy grail” would allow for the earliest possible identification with the goal of preserving or improving vision, not limiting damage after the fact, Dr. Belin said.
Dr. Belin then went on to discuss the ABCD classification, which is measured at the cone. He described it as: A) Anterior radius of curvature from a 3.0-mm zone centered on the thinnest point. B) Posterior (back) radius of curvature from a 3.0-mm zone centered on the thinnest point. C) Minimal corneal thickness (not apical). D) Best spectacle-corrected visual acuity.
The real goal of this wasn’t just the classification, Dr. Belin said, but it was to determine method and document true progression of the disease. This classification tells you when you have statistically significant change on each anatomical layer, he said.
Deborah Jacobs, MD, Boston, discussed expanding options in rigid contact lenses, especially designs for keratoconus. She noted lenses that have innovative base curves to accommodate the cone and also innovative optics to neutralize characteristic decentration and coma.
Asim Ali, MD, Toronto, Canada, discussed management of pediatric keratoconus, which he said can be seen in children as young as 4 years. In pediatric patients, it’s a more severe stage of disease, he said, and can be associated with trisomy 21, vernal keratoconjunctivitis, and other conditions.
Diagnosis criteria is the same as with adults, Dr. Ali said, and reliable topography/tomography is critical. It’s also key to have experienced technicians, he said. If topography is not possible, pachymetry/keratometry may be used or an exam under anesthesia, if needed. Retinoscopy generally detects late-stage disease, he added.
Dr. Ali also stressed caution in trisomy 21 patients because they may have thinner and steeper corneas at baseline. Progression can be much faster than in adults (but not in all patients). If the patient is suspect, he recommended following closely.
Corneal crosslinking is approved in patients over age 14, Dr. Ali said. For younger patients, it’s off label. Criteria for treatment varies between studies, he noted, and some advocate for treatment after diagnosis without waiting for progression.
In terms of crosslinking outcomes, Dr. Ali said that most studies report only 2-year outcomes (or less). He also stressed the importance of following children in the long term because of the high recurrence rate.
However, crosslinking is not the same as visual rehabilitation, Dr. Ali said. Many patients who cannot tolerate contact lenses will need to have surgery. He added that there are good outcomes in children with DALK and PKP, but there are no comparative studies between the procedures.
Dr. Ali prefers DALK, because it is advantageous in eye rubbers, developmental delay, and trisomy 21. He said it also offers greater tectonic strength and a decreased risk of rejection. He also considers tarsorrhaphy with trisomy 21.
Keratoconus is often detected late in children and can progress quickly, Dr. Ali said. Crosslinking is an effective therapy but is associated with long-term failure and patients need ongoing follow up. Surgical therapy is often required in these patients.
Editors’ note: Dr. Belin has relevant financial interests with Oculus, Avedro, and CXLO. Dr. Jacobs has no relevant financial interests. Dr. Ali has no relevant financial interests.
Dry eye and ocular surface disease
Another section of Cornea Subspecialty Day covered topics relating to dry eye and ocular surface disease. Clara Chan, MD, Toronto, Canada, highlighted a stepwise approach to management of ocular cicatricial diseases, stressing the importance of staged management.
Step 1: Get any glaucoma optimized. This involves early placement of a tube shunt.
Step 2: Correct lid abnormalities. If uncorrected, there is poor prognosis for any reconstruction efforts.
Step 3: Suppress inflammation and autoimmune responses. This can be done topically or systemically, but it can also take months to years.
Step 4: Do a trial scleral contact lens. Dr. Chan said this has “revolutionized” how she’s managed these patients. The PROSE device (BostonSight) or impression molded EyePrintPro (EyePrint Prosthetics) can be used.
Step 5: Ocular surface stem cell transplant. You can replace conjunctiva or stem cells. Fornix reformation is important because patients can then wear protective contact lenses.
Step 6: Optical cornea transplant. Continue ongoing surveillance for glaucoma, infection, corneal melt, retinal detachment, sterile vitritis, endophthalmitis, etc.
Dr. Chan shared several things to have in your “ocular surface optimization tool box,” including lubricants, anti-inflammatories, nutritional support, lid margin disease management, and adjuncts.
Editors’ note: Dr. Chan has no relevant financial interests.
Updates in keratoplasty and keratoprosthesis
During an afternoon session focusing on keratoplasty and keratoprosthesis topics, Mark Terry, MD, Portland, Oregon, shared instances where he still turns to PK.
He first went through the obvious clinical settings for PK and also noted that there are a number of clinical settings where PK is just one option among many. He then went into detail on when he would choose PK in “controversial clinical settings.” For fungal infections of the interface after DALK or EK, for example, Dr. Terry recommended doing a PK.
Interface infections are sequestered from medical treatment, he said, and greater than 80% go on to PK even after medical treatment. You can also risk fungal endophthalmitis if medical therapy fails, he said.
Dr. Terry also mentioned ulcerations/infections requiring a 10-mm or larger graft, in which case he recommended a hybrid graft. PK grafts that go to the limbus and beyond destroy the angle and get extensive iridocorneal adhesions that destroy the endothelium over time, he said. Dr. Terry defined a “hybrid” graft as a full thickness graft that is laid over a recipient bed that has a deep lamellar periphery and a central full thickness trephination. Using this, the angle is preserved, glaucoma is avoided, iridocorneal adhesions are prevented, and astigmatism is minimized, Dr. Terry said.
Editors’ note: Dr. Terry has no relevant financial interests.
Everyday topics in glaucoma rethought
A morning session at Glaucoma Subspecialty Day addressed a variety of topics, including medication after MIGS, neuroprotection in glaucoma, and how much medication is too much, among other presentations.
Alex Huang, MD, PhD, Pasadena, California, described how trabecular meshwork MIGS that target the proximal region could complement drugs that hit the distal region. He also said with trabecular meshwork MIGS a quick steroid taper is recommended to avoid a prolonged steroid response. Just how collaborative MIGS and medicines will be has not been well researched. Dr. Huang said time has yet to tell whether 2+2 is going to equal 3, 4, or 5 with MIGS and meds.
One of the unmet needs in glaucoma is finding better treatments beyond IOP (neuroprotection, regeneration, and neuroenhancement), Jeffrey Goldberg, MD, PhD, Palo Alto, California, said. There is a window of time between cell dysfunction cells and cell death where treatments could be targeted, he said.
One drug that is in Phase 2 clinical trials is Renexus (NT-501, NeuroTech), which is loaded with RPE cells expressing a high dose of ciliary neurotrophic factor. In the Phase 1 trial that included 11 patients, researchers saw rapid thickening of the nerve fiber layer, improvement in the visual field index, and no adverse events, Dr. Goldberg said. Phase 2 1-year data is closing this month, and Dr. Goldberg said they are initiating an extension to add an arm to the study that will investigate whether two implants have more of an effect. Other trials include a Phase 1/2 with recombinant human nerve growth factor as an eye drop, a Phase 1b anti-C1A intravitreal injection, and virtual reality goggles to look at visual stimulation.
What about medications—how much is too much? Janet Serle, MD, New York, said there are now seven glaucoma medications, providing a “great boom for us as clinicians and treating our patients.” Overall, there is limited data on newer drugs and efficacy of combinations and delaying surgery, Dr. Serle said. There is also “no magic number” of medications—what works for one patient might be a burden for another. According to the literature reported by Dr. Serle, the max number of medications that are effective, tolerated, and complied with varies widely.
Editors’ note Dr. Huang, Dr. Goldberg, and Dr. Serle have financial interests related to their comments.
Glaucoma and the cornea
Several presentations during an afternoon Glaucoma Subspecialty Day session discussed aspects of glaucoma and corneal disease.
Glaucoma is profoundly interrelated to corneal diseases, Keith Barton, MD, London, U.K., said. Not only are there challenges in measuring pressure accurately in the presence of corneal disease, but glaucoma medications in and of themselves can exacerbate preexisting ocular surface conditions. The latter is related to preservatives and, sometimes, drug allergies. Glaucoma surgery also exacerbates corneal endothelial cell loss and is the biggest risk factor for graft failure, Dr. Barton said.
Dr. Barton discussed research that supports selective laser trabeculoplasty (SLT) to reduce medication burden. Patients with significant corneal problems might not be candidates for SLT, but Dr. Barton said they need good IOP control before endothelial transplants. He noted tube shunts for long-term IOP control and cyclophotocoagulation for emergency control.
Michael Banitt, MD, Seattle, cited data in his presentation that found limited graft survival in the presence of tubes or trabs, due to significant, persistent corneal edema. There is nothing to be done with corneal edema after tubes or trabs, but he said hypotony and shallowing of the anterior chamber should be avoided, and, in the case of tubes, one should use gonioscopy to make sure the tube enters the trabecular meshwork not anterior to Schwalbe’s line.
John Berdahl, MD, Sioux Falls, South Dakota, discussed MIGS in the context of corneal disease. MIGS procedures, he said, lower IOP and medication burden, which can improve ocular surface conditions exacerbated by drops. He described a study that saw a lower OSDI score and increased tear breakup time after phaco-iStent (Glaukos).
On the flip side, some MIGS procedures have been associated with corneal issues. Dr. Berdahl noted the CyPass (Alcon) withdrawal due to instances of endothelial decompensation. He also highlighted trimming CyPass if it is sticking up too much. He specifically mentioned cutting forceps developed by MST, which retain the trimmed device and avoid side-to-side cutting motion that could cause cyclodialysis cleft.
Editors’ note: Drs. Barton and Berdahl have financial interests related to their comments. Dr. Banitt does not have financial interests related to his comments.
Considerations for cataract surgery in presence of glaucoma
The final section of Glaucoma Subspecialty Day addressed the implications of glaucoma on cataract surgery. Presentations by Thomas Samuelson, MD, Minneapolis, and Constance Okeke, MD, Norfolk, Virginia, addressed cataract surgery in eyes with preexisting tubes or trabs.
In eyes with a preop IOP within target range on no meds, Dr. Samuelson said he will perform routine phaco if the bleb is diffuse and uninflamed. If it is contracted and inflamed, he will consider perioperative antimetabolites. For both situations, he will consider prolonged steroid treatment and will anticipate that IOP may not be as well controlled postop as it was preop.
In eyes with a higher preoperative IOP or those on a complex medication regimen, Dr. Samuelson considers adjunct glaucoma interventions, such as GATT. He might needle the bleb with mitomycin-C and might repeat the trab or tube, depending on the status of the limbal tissue.
For eyes with a lower preop IOP than target range, Dr. Samuelson offered caution for IOL calculations, said axial length should be compared with the fellow eye. He noted that phaco could bring IOP within normal range. If hypotony-related maculopathy is evident, he considers revision prior to phaco.
Dr. Okeke offered a few pearls for cataract surgery in these patients as well. Preop evaluations need more time and thought, she said, and patient expectations need to be addressed early. MIGS offers the potential to minimize IOP spike risk, and inflammation should be treated aggressively, Dr. Okeke said. Surgeons need to be prepared for the potential to reposition themselves and incisions depending on bleb positioning. Tubes should be assessed and managed during the procedure if too long or anterior, Dr. Okeke said.
Editors’ note: Dr. Okeke has financial interests related to her comments. Dr. Samuelson does not have financial interests related to his comments.