- Course gives insights on gonioscopy, ‘the golden tool’
- Experts update on the ‘why, which one, and how’ for intracameral antibiotics
- Keratoplasty topics
- Complex penetrating keratoplasty
- Crosslinking in post-refractive ectasia and post-penetrating keratoplasty
Course gives insights on gonioscopy, ‘the golden tool’
An instructional course at the 2022 AAO Annual Meeting highlighted the topic of gonioscopy, describing it as “the golden tool.” The course covered the use of gonioscopy for diagnostic and decision-making purposes, the surgical aspects of gonioscopy, and what to do when gonioscopy doesn’t give you the full story.
Ahmed Abdelrahman, MD, presented on using gonioscopy to make diagnostic and subsequent management decisions. He described the two types of gonioscopy: direct and indirect, getting into specifics for each.
He then provided tips and tricks for gonioscopy, which included preparing your “stuff” (the lens, anesthesia, coupling agent, etc.), dim the room (you don’t want the pupil too dilated), and reassure the patient (it’s important there is no pain and to manage it). From there, the patient looks upward, and the surgeon supports the upper lid, pulls the lower lid downward, and applies pressure (don’t push). It’s important when using the lens, Dr. Abdelrahman said, to use verbal anesthesia at this stage. Dr. Abdelrahman also advised viewing the inferior angle because it is the widest and has darker pigmentation.
Dr. Abdelrahman described the 0–IV stages of angle grading and the different grading systems. He also discussed the importance of pigmentation and gave several case examples that showed how gonioscopy informed his management decisions.
Zeynep Aktas, MD, presented on surgical gonioscopy, which she said is key to angle surgery and of importance in the MIGS era. Even surgical gonioscopy pearls begin with office-based gonioscopy, Dr. Aktas said. Office-based gonioscopy is important for surgical planning, becoming familiar with angle structures, and testing patient tolerability and informing anesthesia selection. It’s important to know angle anatomy, with the scleral spur being the surgical landmark that separates the ciliary body and the pigmented trabecular meshwork.
In the OR, for success with surgical gonioscopy, the surgeon needs to have a stable globe; there needs to be no Descemet’s folds; the surgical area should be clear; the surgeon should have a simultaneous view with manipulation possible; and surgical instruments should be accessible, Dr. Aktas said.
Positioning in the OR is the “most important part,” Dr. Aktas continued. Take a temporal approach, tilt the head 30–40 degrees away, tilt the microscope 30–40 degrees toward you, and increase magnification and light intensity.
Other surgical basics that Dr. Aktas shared included to keep the gonioscopic view clear throughout surgery, use enough coupling agent, pay attention to the limbal vascular structures, pressurize the eye, and if bleeding occurs, wash out the AC and reinject OVD.
With so many different surgical techniques and implants relying on gonioscopy, Dr. Aktas said, “we should definitely be familiar with angle structures to do these procedures well.”
In the last presentation of the course, Mohamed Sayed, MD, described a case where gonioscopy did not tell the whole story, where it was not the golden tool.
The case involved a 67-year-old phakic male who had hypotony in his right eye. In this eye he had a history of exudative AMD for which he was receiving intravitreal bevacizumab; he denied a history of trauma. Three days after an intravitreal injection, the patient presented with hypotony, anterior chamber cells, and vitreous hemorrhage. He was started on treatment but recurrent hypotony continued, and he was referred to Dr. Sayed for further care.
Dr. Sayed said he expected cyclodialysis cleft, but careful gonioscopy looked normal 360 degrees and was comparable to the fellow eye. From there, UBM identified a posterior cyclodialysis cleft in the right eye. This is the rarer variant of cyclodialysis cleft, with 99% of them being anterior.
Dr. Sayed said he wasn’t sure the cleft and ciliary body detachment viewed on UBM was the only factor for hypotony, so he consulted uveitis service and despite subsequent uveitis treatment, vision remained poor and pressure low. The patient was consented for pneumatic retinopexy with cryotherapy to achieve cleft closure, but prior to that procedure he presented to the ER with severe pain in his right eye. Pressure at that time was 60 mm Hg. UBM showed spontaneous closure of the cyclodialysis cleft and complete resolution of the ciliary body detachment.
Dr. Sayed said his take-home message was that UBM can be a useful adjunctive tool when gonioscopy is inconclusive. Unrelated to this case, Dr. Sayed also said gonioscopy is important for postop evaluation of patients with tube shunts. He said evaluating proximity of tube entry site to the cornea at the anterior chamber angle can be useful in predicting endothelial cell loss. The ideal tube locations bisecting the angle at the scleral spur, and early revision should be considered if the tube entry site is anterior to the trabecular meshwork.
Editors’ note: The physicians have no financial interests related to their comments.
Experts update on the ‘why, which one, and how’ for intracameral antibiotics
David Chang, MD, Neal Shorstein, MD, and Steve Arshinoff, MD, hosted an instructional course about intracameral antibiotics. Each shared a wealth of peer-reviewed literature and perspectives on intracameral antibiotic prophylaxis.
“This is really an area still with some controversy,” Dr. Chang said, noting that all antibiotic prophylaxis is off label, even topical.
The ESCRS study of prophylaxis of postoperative endophthalmitis after cataract surgery, which found the efficacy of intracameral cefuroxime significantly reduced incidence of endophthalmitis and led to the approval of an antibiotic in Europe, was published 16 years ago, Dr. Chang said. Since then, ASCRS has conducted several surveys with some questions about antibiotic prophylaxis. In 2007, for example, 30% of ophthalmologist respondents said they used intracameral antibiotics; in 2021, that number was 66%. In earlier years, most were using it in the bottle, and now most are directly injecting it, Dr. Chang said. The 2021 survey also found that 93% of ophthalmologists would use an intracameral antibiotic if one were approved.
In the U.S., moxifloxacin is the most common antibiotic being used intracamerally (73%). Vancomycin, as of 2014, was used among 52% of ophthalmologists who used intracameral antibiotics, but after published reports of HORV and recommendations against its use due to this rare complication, its use significantly dropped. Dr. Chang gave several details regarding investigation of HORV associated with intracameral vancomycin.
Dr. Chang also spoke about data regarding moxifloxacin, such as that from Aravind Eye Hospital that found a four-fold reduction in endophthalmitis with moxifloxacin use. More specifically, Dr. Chang also shared that intracameral antibiotic use is even more beneficial if you break the capsule (he cited research that has found a seven-fold increase in infection risk with PCR, but it is lower if you use intracameral moxifloxacin).
“Even if you think you don’t need intracameral antibiotics, if you break the capsule, that changes it … that’s when you should use it,” Dr. Chang said.
He later said that secondary IOLs are another group where you should consider intracameral antibiotics.
Dr. Chang talked about the different ways to obtain intracameral antibiotics in the U.S. (again, for off-label use), either the branded topical version (Vigamox, Novartis) or from a compounding pharmacy. Dr. Chang said that if you’re getting the drug from a compounding pharmacy, 503B pharmacies are FDA registered. Compounded options, Dr. Chang said, are affordable and have a long shelf life.
There are three methods for using moxifloxacin intracamerally, Dr. Chang said: 1) 0.1 mL of 0.5% moxifloxacin; 2) 0.3–0.4 mL of 0.15% moxifloxacin; 3) 0.5 mL of 0.1% moxifloxacin. Dr. Shorstein detailed in his presentation that moxifloxacin is a concentration-dependent drug. As such, he said that he prefers to use a more dilute concentration (0.1%) at 0.5 mL.
“We think we get consistently higher doses injected with 0.5 mL of 0.1% moxi,” he said.
Editors’ note: The physicians have no financial interests related to their comments.
Keratoplasty topics
During a subspecialty day section relating to cornea, experts presented on keratoplasty topics.
Massimo Busin, MD, discussed superficial anterior lamellar keratoplasty (SALK), deep anterior lamellar keratoplasty (DALK), and variants. He noted that anterior lamellar keratoplasty dissection techniques may include using manual, “big bubble,” microkeratome, and femtosecond laser techniques. However, he noted that manual technique is difficult, and he said that femtosecond laser is not good because though it cuts nicely, the deeper you go with the dissection, the worse the quality of the surface.
This leaves the options of using “big bubble” or microkeratome. The “big bubble” technique works well, Dr. Busin said, but it has the problem that it removes all the stroma, and sometimes that’s not necessary. He said that microkeratome is another option, but the problem is that you can’t go that deep because you’re risking perforation.
Dr. Busin said that SALK is not as popular as DALK. SALK compared to LASIK, he said, is like having a “living contact lens,” and it also has fast healing (around 1 month) and minimal postop refractive error. Meanwhile, he said that DALK compares to PK, with sutures, 1-year healing, and potential problems with astigmatism.
He added that SALK doesn’t work for surface irregularity, like after a corneal ulcer.
DALK, Dr. Busin said, can offer results as good as PK. However, he noted that there are no short-term advantages over PK, as it may take years to appreciate the greater advantage of DALK.
With PK, Dr. Busin said surgeons are limited to 8 mm because, if you make it larger, the rejection risk rises dramatically. With DALK, larger grafts (9 mm) can be used, he said.
Before wrapping up his presentation, Dr. Busin also mentioned Descemet stripping only (DSO).
Editors’ note: Dr. Busin has no relevant financial interests.
Complex penetrating keratoplasty
Irit Bahar, MD, gave a presentation on complex penetrating keratoplasty, noting that she considers these “complex” cases either high risk or surgically challenging.
The first high risk she discussed was chemical burns, which present the challenge of limbal stem cell deficiency (LSCD), corneal neovascularization, delayed healing, and high risk of rejection. Solutions in these cases may include using amniotic membrane, tarsorrhaphy, limbal stem cell implantation before PKP, or keratoprosthesis, Dr. Bahar said.
Dr. Bahar noted that when LSCD is present, PKP is not normally performed as the primary procedure. The appropriate strategy, she said, is to first perform a limbal stem cell transplant followed by a later keratoplasty if it’s still necessary.
She added that amniotic membrane implantation associated with PKP reduces early and mid-term complications of corneal grafts in patients with high risk of failure.
Another challenging type of case that Dr. Bahar highlighted were significantly vascularized corneas. Solutions for this, she said, include anti-VEGF injection, cautery, crosslinking, or mitomycin intravascular chemoembolization (MICE).
Significantly vascularized corneas, she said, have a much higher risk of graft rejection. According to the Collaborative Corneal Transplantation studies, corneas with deep stromal NV in two or more quadrants are considered “high risk,” she said, adding that the onset and severity of rejection is determined by degree and depth of preoperative corneal NV.
One solution, she said, is to use perilimbal anti-VEGF injection. Once corneal rejection occurs, the likelihood of reversal depends on the degree of corneal vascularization. Experimental studies have shown that anti-VEGF improves corneal graft survival, Dr. Bahar said, however, this strategy is only able to inhibit progressive corneal NV. The regression of well-established blood and lymphatic vessels is still a challenge, she said. Other potential treatment options are to use corneal crosslinking or MICE.
Editors’ note: Dr. Bahar has financial interests with a variety of ophthalmic companies.
Crosslinking in post-refractive ectasia and post-penetrating keratoplasty
Kathryn Hatch, MD, discussed using crosslinking for post-refractive ectasia and post-penetrating keratoplasty.
In general, you want to detect ectasia and keratoconus very early, she said, and you should be performing regular topographies in patients, especially after refractive surgery, RK, and transplant surgery to help detect earlier.
Crosslinking strengthens the corneal biomechanics and increases tensile strength of the collagen fibrils. You want to have patients undergo crosslinking as soon as possible to prevent further steepening of the cornea, Dr. Hatch added.
During her presentation, Dr. Hatch also highlighted pearls for crosslinking in certain scenarios. For crosslinking post-LASIK, she said to look for change in refractions and topography changes. She also said to be mindful of flaps and incisions post-RK. She stressed that it’s important to treat the ocular surface, as these eyes tend to have a high incidence of dry eye. She added that it’s important to always ask about and discuss eye rubbing and sleep patterns.
For post-RK eyes, Dr. Hatch noted that there may be diurnal fluctuations, and it’s important to be mindful of RK incisions and watch for potential wound gape. Similarly to post-LASIK eyes, she said to look for change in refractions and topography changes, to treat the ocular surface, and to ask about the eye rubbing and sleep patterns in these patients as well.
Post-PKP, Dr. Hatch said it’s important to perform regular topography and do comparison maps. She suggested considering prolonged bandage contact lens use, as epi defects can take longer to heal.
Editors’ note: Dr. Hatch has financial interests with a variety of ophthalmic companies.
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