- When to still use DSAEK
- Differentiating between bacterial and fungal keratitis
- Best practices for angle-based surgery
- Late-breaking retina topics
When to still use DSAEK
During a cornea session at the AAO Annual Meeting, Jodhbir Mehta, MD, PhD, discussed “DSEK: When DMEK Just Won’t Do,” specifically highlighting cases in which he will still use DSAEK.
He began by broadly discussing corneal transplantation and the various techniques that are available and how the field has shifted over the years; EK is the most dominant now. Dr. Mehta started doing DSAEK around 2005.
In terms of PK vs. EK, Dr. Mehta noted that PK greatly affects the refractive quality of the cornea, while EK maintains the host corneal shape and refractive quality and gives better VA and faster visual rehabilitation.
A change in DSAEK technique helped to improve outcomes, Dr. Mehta said. Changing donor insertion had several downstream effects including reduced IPGF, better endothelial cell count, and reduced risk of donor inversion. There were expanded indications for EK since you did not have to have perfect clarity. This increased the rates of DSAEK surgery, he said.
Now we’re in the era of DMEK, Dr. Mehta said. It offers faster visual rehabilitation vs. DSAEK over the first 6–9 months, lower rates of rejection, and less aberration from the posterior corneal surface (better VA). However, there is a higher rate of cell loss/rebubbling vs. best DSAEK results, he said.
In 2015, the challenges with DMEK insertion were that you needed good visibility in order to manipulate the graft in the anterior chamber; there were higher rates on inversion; there were higher rates of IPGF; and you needed an intact iris lens diaphragm. A change in DMEK technique help to remedy some of these concerns. By changing the technique from an endo-out procedure to an endo-in, there is more control of the graft, he said. There is no reliance on the lens iris diaphragm, minimal manipulation in the anterior chamber, no need to shallow the anterior chamber, and the graft opens in a natural position.
Despite these improvements, Dr. Mehta said there is still a need for DSAEK in 2023. Dr. Mehta shared several case in which he would prefer to use DSAEK: patients who present later and have severe stromal edema with very poor visibility, patients with severe stromal edema with chronic changes where they may need to undergo DALK, and children in whom posturing is an issue and multiple general anesthesia for DMEK rebubbling is a higher risk.
DSAEK is still the most common EK procedure performed worldwide, Dr. Mehta said. While it was limited in the early days to cases with moderate corneal clarity, change in graft insertion techniques has allowed DASEK to be performed in more challenging cases. DMEK numbers have also been rising and are equivalent or have surpassed DSAEK in certain centers, he said.
In standard endo-out DMEK, good visibility is a must, but changes in technique to the endo-in technique have allowed DMEK to be performed in more complex cases, Dr. Mehta said. However, he stressed that DSAEK is still useful in cases of severe stromal edema, patients with chronic stromal scarring who may need to undergo DALK, or children in whom posturing is an issue.
Editors’ note: Dr. Mehta has no relevant financial interests.
Differentiating between bacterial and fungal keratitis
Prashant Garg, MD, shared ways to differentiate between bacterial and fungal keratitis. Timely institution of appropriate therapy is crucial in these cases, he said, and they can be caused by a variety of microorganisms.
Dr. Garg noted that clinical distinction is not easy, and he shared several examples where he thought an infection was bacterial and it turned out to be fungal, and vice versa. Lab diagnosis may prove to be helpful in narrowing down the type.
He said you can use corneal scraping, smear, and culture. The pros of this are visualization of organisms on microscopy and immediate treatment, identification of growth on culture, antibiotic susceptibility, and it helps identify rare or uncommon organisms. However, cons are that it requires a well-equipped laboratory and the support of a trained microbiologist, as well as an additional cost.
In vivo confocal microscopy can also be used in the clinic, Dr. Garg said. Advantages of this are the prompt treatment initiation, it helps assess the depth of infection, it can be repeated during treatment for monitoring response, and it has a high sensitivity and specificity. But disadvantages are bacteria are too small to be visualized, patient cooperation is essential, it is user dependent, and comes with a high cost and low availability.
There are also other tests in the market under investigation. Dr. Garg mentioned molecular assays, and he said that machine learning is gaining momentum as well.
In terms of treatment, Dr. Garg covered different options, depending on the type of ulcer. If you have a non-severe ulcer that is unlikely to be fungal or Acanthamoeba, and the smear is negative or shows bacteria, he said a broad-spectrum antibiotic can be used. You can also use monotherapy or combination, depending on the size of the infiltrate.
For a non-severe ulcer that is likely fungal, and the smear shows fungal filaments, Dr. Garg recommended treatment with antifungal agents. Treatment with antifungal agents must be started only once fungi have been documented, he added.
Dr. Garg also said to avoid cocktail therapy because there is risk of drug toxicity.
For a non-severe ulcer that is likely fungal, but the smear is negative, refer to a center equipped with a microbiology facility.
Severe keratitis cases must be treated at a center with requisite expertise, Dr. Garg stressed. Clinical examination is valuable but not perfect, and simple microscopy offers a reasonable option to start treatment.
Editors’ note: Dr. Garg has no relevant financial interests.
Best practices for angle-based surgery
During a glaucoma session, Arsham Sheybani, MD, discussed best practices in angle-based surgery. The best practice for angle surgery is doing it, he said, adding that it’s hard when you’re just doing a procedure once a month.
He suggested that before you incorporate MIGS, incorporate gonioscopy. Dr. Sheybani offered several other glaucoma surgery pearls:
- Document the TM pigmentation (use trypan)
- Be mindful of under-turning the eye
- Control heme – pre- and post-procedure
- Consider performing your TM-based procedure pre-phaco
- Do not overfill the eye with OVD (except for pressurized viscodilation)
- Make space if the device meets resistance
- Do not leave devices in the wrong tissue plane
Editors’ note: Dr. Sheybani has financial interests with several ophthalmic companies.
Late-breaking retina topics
During a session covering late-breaking developments in the retina field, Sumit Sharma, MD, presented “Intravitreal Sustained-Release Dexamethasone Implant for Diabetic Macular Edema and RVO: Six-Month Results from the First-in-Human Phase 2 RIPPLE-1 Trial.”
The IBE-814 IVT technology (Ripple Therapeutics) offers advantages over polymer-based delivery systems, Dr. Sharma said. The IBE-814 IVT has durability of 6–9 months, uses a small needle size, no pro-inflammatory polymer degradation products, and a low dose.
The RIPPLE-1 was the first-in-human study designed to evaluate the safety and efficacy of the IBE-814 IVT implant, Dr. Sharma said. It was done at 21 clinical sites in four countries, with 60 subjects in 2 dose groups (a low dose group with a single 70-microgram injection and a high dose group with two 70-microgram injections).
Dr. Sharma shared the 6-month results, which showed reduced CST in all cohorts and improved or stable BCVA in all cohorts. In terms of safety, he said the results were comparable to other intravitreal steroids. Comparison to historical treatment data showed reduction in treatment burden with IBE-814 IVT. Further long-term follow-up is in progress, and the study concludes in 2024.
W. Lloyd Clark, MD, presented “First Ever Home OCT-Guided Management of Treatment Experienced Neovascular AMD Patients.” Previously, there has been observation study on this. Studies to date provided daily OCT imaging, and gave unique insights into fluid exposure and dynamics between office visits. However, office visit decisions were still made based on in-office exams. This study takes it a step further, he said. The purpose of the study was to understand feasibility and impact of nAMD management using home OCT data. The key elements were patients scanning images at home, a monitoring center, an AI-based cloud, and the treating retina specialist. This study included 15 patients with diagnosed nAMD in at least one eye. There was a 6-month follow-up period, and patients were to perform daily home OCT scan. Patients were invited to the office based on physician review of the home OCT data.
While there were several study limitations (a small cohort, non-randomized study with retrospective treatment history as a comparator, treatment types varied based on investigator discretion, and the study used Snellen VA measurements), Dr. Clark said there was a statistically significant reduction in treatment frequency and increase in treatment interval from 8 to 15.3 weeks. There was no change in VA at 6 months. He said that home OCT was easy for subjects to use, resulting in good compliance with the home imaging schedule and early disease activity detection.
Editors’ note: Dr. Sharma has financial interests with several companies. Dr. Clark has financial interests with Notal Vision.
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