- Surgical management of infectious keratitis
- Complex keratoplasty
- Virtual reality perimetry
- Additive corneal surgery for keratoconus
Surgical management of infectious keratitis
During a cornea-focused session, Sonal Tuli, MD, discussed the surgical management of infectious keratitis, going through options for these patients and why you need a surgical intervention.
Sometimes you need a temporary fix to get people stabilized, she said, and you can do medical or surgical treatment. You also may need surgical management if there’s a lot of inflammation that won’t let the eye heal or if the infection is out of control.
She shared several principles for management, with three modalities: maintain structural integrity temporarily to allow the underlying tissue to heal; scaffold with tissues that reduce inflammation/infection or enhance healing; and replace infected tissue by corneal grafting.
Dr. Tuli said the easiest thing she likes to address is peripheral ulcer. It’s usually easy to use a glue in these cases, and there are several glue options available. She noted that these come in pipettes, are soft, and release about a molecule at a time. You want to paint it in and mind the amount of glue you’re using, Dr. Tuli said, because it does expand as it dries. If you have peripheral ulcer, let it heal, and a few months later, the glue falls off, and you don’t need surgical intervention. However, if you have a lot of inflammation, glue will cause even more inflammation.
Amniotic membrane could work well, as this helps with inflammation and has growth factors that let the epithelium heal over it.
You don’t always have to cover the entire cornea. Dr. Tuli went on to discuss micro PKP, which she said are nice for peripheral infections. The advantage is that only a small percentage of corneal endothelium is replaced, so rejection is not an issue. You don’t have to make a big central corneal graft.
Also for peripheral infections, a crescent graft could be used. Dr. Tuli described this as using a smaller size trephine to make the outer edge and larger trephine to make the inner curve. You make a crescent in the donor as well and sew it on. You’ve only replaced a small amount, and they heal very well, she said.
Lastly, Dr. Tuli noted that intrastromal injections are particularly useful in fungal keratitis.
Editors’ note: Dr. Tuli has no relevant financial interests.
Complex keratoplasty
W. Barry Lee, MD, shared tips for success in complex keratoplasty. He first noted a number of complex situations where keratoplasty may be required: keratolysis/impending perforation/perforation (could include infectious keratitis, autoimmune keratitis, or neurotrophic keratitis), anterior segment trauma, prior glaucoma surgery, multiple grafts failures, or limbal stem cell deficiency.
For perforation or complex cases, it’s easier to do them under general anesthesia, Dr. Lee said. Local blocks are ineffective with prior infection.
For infectious keratitis, Dr. Lee suggested treating it medically for as long as you can. You want the eye to be as quiet as possible when you go to the OR, though he recognized that sometimes it’s not possible to wait. If there’s a small perforation, using a glue adhesive to stabilize a small perforation is helpful. It can buy time to get the eye more quiet.
Dr. Lee did offer one exception to waiting: aggressive fungal infections, like Scedosporium or Paecilomyces. These can be tough to manage.
Make sure you include the entire zone of infection or perforation in the recipient trephination, Dr. Lee said. If you leave a bit behind, the edge will likely get re-infected.
For cases requiring large donor diameters, Dr. Lee said to oversize the donor more than your typical routine case. You may need to oversize by 0.75 to 1 mm if limbus to limbus graft is required.
He also said to reorganize the anterior chamber. The iris can be our enemy in these situations. Break peripheral synechiae and sweep the angle with a cannula or iris spatula. Break posterior synechiae, and remove anterior chamber debris.
One of the most important things with complex or infectious cases, Dr. Lee said, is to make a generous peripheral iridectomy, and you may even want two. These cases are at high risk of pupillary membranes and subsequent pupillary block from synechiae and membranes.
For prior glaucoma surgery, you may need to reposition or shorten a prior tube shunt. If those are hitting the cornea, it’s not a good sign, he said.
Dr. Lee also said to avoid running sutures in therapeutic keratoplasty. There is high risk of suture loosening, vascularization, and cheese wiring as the wound contracts, causing early wound dehiscence.
Dr. Lee also offered some postoperative tips. He noted that autoimmune melts are a particular problem. You must get systemic therapy, and he suggested referring to rheumatology for management of systemic disease.
With therapeutic keratoplasty cases for infection, continue a topical antimicrobial for several weeks after surgery, and watch for recurrent infection. The goal is two-step surgery. The first graft stabilizes the eye and eradicates infection, and the second graft is for optical improvement and corneal clarity.
He suggested holding your steroids in therapeutic keratoplasty for infectious keratitis. Make sure there is no recurrence prior to starting, and consider cyclosporine as a temporary alternative.
Glaucoma risk is high after therapeutic keratoplasty, Dr. Lee said, adding that posterior and peripheral synechiae are common, trabecular meshwork damage is common, and intraoperative PI is helpful.
In terms of neurotrophic corneal melt repairs, tarsorrhaphy may be necessary. You may need to enlarge if delayed epithelial healing persists. Consider adjuncts to postoperative healing like autologous serum, cenegermin, or amniotic membrane.
For those who have had multiple graft failures, Dr. Lee suggested testing for CMV with PCR of the tissue and aqueous. He also suggested an aggressive postoperative topical steroid regimen, and consider oral immunosuppressive therapy.
Editors’ note: Dr. Lee has no relevant financial interests.
Virtual reality perimetry
During a ‘Hot Topics’ session, Natasha Nayak Kolomeyer, MD, discussed virtual reality perimetry. She first noted that virtual reality is an immersive technology that uses a head-mounted device. While VR has transformed the gaming industry, the technology has growing applications in the health space as well. Perimetry is the systematic assessment of visual function across the visual field (VF), and it plays a pivotal role in diagnosis and monitoring of glaucoma and other optic neuropathies.
Dr. Kolomeyer noted that AAO recommends at least an annual VF testing for glaucoma, and recent studies recommend even more frequent testing to identify progression early. However, she said that more than 75% of glaucoma patients received less than one VF test per year. Additionally, standard perimetry can be burdensome for patients and the practice.
Dr. Kolomeyer listed a number of theoretical advantages of VR including: reduced space and lighting requirements compared to standard perimetry, the fact that it’s portable (allowing for home and remote monitoring), improved patient comfort and access with more flexible positioning, easier to capture children’s interest, automated gaze tracking and instructions could free up technician time, potentially time-saving and improvements to workflow, and potentially money-saving. Reducing barriers to VF testing with VR may allow more frequent testing and may promote earlier identification of progression, Dr. Kolomeyer said.
There has been an explosion of devices in this space, but many of them vary. She said the VR perimeters may vary in terms of stimulus, response, or processing. One big way they also vary is validation. Data from one VR perimeter does not validate another.
So, how should you critically analyze each VR perimeter? Dr. Kolomeyer noted patient comfort, satisfaction, and feasibility; the ability to stratify different severity of disease; sensitivity to disease progression; and other factors. While VR perimeters might not be able to replicate standard perimetry, we want to be assured that they are not inferior to what we already have in our office, Dr. Kolomeyer said. Keep in mind that standard perimetry has pitfalls as well, including test-retest variability, pre-perimetric glaucoma, and disagreement between structural and functional tests.
Dr. Kolomeyer noted that there is room for improvement. She said there is varying degree of validation for specific VR perimeters. Small sample size and often single center enrollment limit generalizability, and the quality of study design is variable. She added that we need more longitudinal data.
Editors’ note: Dr. Kolomeyer has financial interests with AbbVie, Allergan, Aerie, Diopsys, Elios, Equinox, Glaukos, Guardion Health Sciences, Nicox, Olleyes, Santen, and Thea.
Additive corneal surgery for keratoconus
William Wiley, MD, also shared a hot topic during his presentation. He discussed options for patients with keratoconus. Penetrating keratoplasty (PK) has been the mainstay of keratoconus treatment since Castroviejo’s pioneering work in 1936, he said.
He noted the crosslinking is another amazing technology, which helps stop the progression of keratoconus. While this can help prevent or delay the need for PK, it is not necessarily designed to improve visual outcomes. It’s ideally done early, but many patients present after already having significant visual loss.
He went on to mention Intacs, full lamellar grafts, CAIRS, and CTAK. Intacs has shown promise but has its drawbacks, he said, adding the cornea generally doesn’t like artificial objects placed in it. A full lamellar corneal transplant helps thicken the cornea but has a graft/host interface that crosses the visual axis and may decrease best corrected visual acuity. Meanwhile, CTAK (corneal tissue addition keratoplasty) and CAIRS (corneal allogenic intrastromal rings segments) are customized processed partial lamellar transplants.
Dr. Wiley showed a case of a 27-year-old female with keratoconus where CTAK was used. With CTAK, Dr. Wiley explained that you send away the Pentacam (Oculus) customized map, individualized from the patient. A plan is created for the patient based on topography and tomography. It customizes size, shape, and placement of tissue.
He also outlined the steps of CTAK, starting with channel creation with the femtosecond laser, channel preparation (using the same tools as Intacs, where you dissect and open up that channel), and finally tissue implantation. CTAK tissue is irradiated, so it’s a little stiffer and easier to place, Dr. Wiley said. You place by hand over hand and push the tissue into the cornea. It’s easy for the surgeon and the patient.
Editors’ note: Dr. Wiley has financial interests with AcuFocus, Alcon, Allergan, Bausch + Lomb, Beaver-Visitec International, Carl Zeiss Meditec, CorneaGen, Dompe, Glaukos, ImprimisRx, Johnson & Johnson, LENSAR, New World Medical, RxSight, Sight Sciences, and STAAR Surgical.
EyeWorld Onsite is a digital publication of the American Society of Cataract and Refractive Surgery.
For sponsorship opportunities or membership information, contact: ASCRS • 12587 Fair Lakes Circle • Suite 348 • Fairfax, VA 22033 • Phone: 703-591-2220 • Fax: 703-591-0614 • Email: ascrs@ascrs.org
Opinions expressed in EyeWorld Onsite do not necessarily reflect those of ASCRS. Mention of products or services does not constitute an endorsement by ASCRS.
Click here to view our Legal Notice.
Copyright 2024. All rights reserved.
