The femtosecond laser is often synonymous with laser in-situ keratomileusis (LASIK). However, its usefulness extends beyond refractive corrections to other ophthalmic procedures such as keratoprosthesis.
According to Dr. Olga Nefedova from the Russian Federation, sometimes keratoprosthesis is the only possibility to restore eyesight in patients with corneal opacities that cannot be treated with optical keratoplasty or stem cell transplant.
“In Russia, the Fyodorov-Zuev keratoprosthesis has been shown to be most effective. It consists of two parts: the keratoprosthesis supporting plate (KSP) made from titanium, and an optical cylinder made from glass. The procedure is done in two stages – first, the implantation of the KSP in the patient or donor cornea, and second, the installation of the optical cylinder after five to six months,” she explained.
Nevertheless, the most common complication of keratoprosthesis is protrusion (33%), whereby the donor/patient’s cornea is perforated with a blade at the time of manual pocket formation.
“According to our observation, the femtosecond laser helps to form a smooth pocket for the implantation of the Fyodorov-Zuev keratoprosthesis with precise control over the depth, width and length of the pocket. Stable positioning of the KSP inside the pocket decreases the risk of protrusion. So far, no tissue bridges within the pocket have been encountered. The use of a femtosecond laser reduces the time for preparation of the corneal-prosthetic complex from an average of 30 minutes to three minutes. In a nutshell, the femtosecond laser simplifies the formation of a Fyodorov-Zuev corneal-prosthetic complex as compared to the standard method using manual microsurgical instruments,” she said.
An Unusual Case of Epithelial Ingrowth
Epithelial ingrowth, which can be due to various reasons, can result in a decrease in best-corrected vision. Dr. Isabeau Houben from the United Kingdom presented a rare occurrence of epithelial ingrowth imitating infection following Descemet’s membrane endothelial keratoplasty (DMEK) surgery.
An 81-year-old Caucasian lady presented at her clinic with Fuchs’ endothelial dystrophy (FED) and cataract. “Because of reduced vision acuity (VA), an uncomplicated left triple DMEK procedure was performed. In the first month post-op, her corneal edema improved and the graft was nicely attached,” she said.
However, seven weeks post-op, the patient returned to the clinic with multiple white interface opacities spread on her cornea, of which a few had a translucent zone surrounding a white mark. Although her corneal edema has resolved, the white interface opacities remained unchanged a few weeks later, even with anti-fungal drug treatment. Ten months later, the white interface opacities increased further although the patient remained asymptomatic and stable. A clinical diagnosis of epithelial ingrowth was subsequently made.
“Epithelial ingrowth is a possible (but not well known) complication after DMEK surgery which can imitate an insidious infection at the graft-host interface. Therefore, interface infectious keratitis needs to be ruled out and whenever in doubt, it is best to start an empirical antimicrobial treatment.
“Epithelial ingrowth can be diagnosed via histopathology (surgical intervention) or confocal microscopy. The best initial course of action is observation. However, in progressive and visually significant cases, surgical intervention (such as DMEK, PK or YAG laser treatment) may be needed. Keep in mind that there’s limited data available about this disease entity,” she said.
A Novel Type of Corneal Availability
As DMEK is increasing in popularity as a procedure to address corneal endothelial dysfunctions, a novel device has emerged which may serve as a better alternative for the treatment of chronic corneal edema.
Prof. Dr. Gerd Auffarth from Germany talked about the EndoArt® artificial endothelial layer implantation in treating chronic corneal edema. The EndoArt® (EyeYon Medical, Israel) is a flexible, 50-μm thin artificial endothelial layer that matches the cornea’s posterior curvature and functions as a fluid barrier at the posterior stroma, replacing the diseased endothelium. The implant works by impeding the transfer of aqueous humor into the cornea, thus reducing corneal edema.
He shared a case of a 58-year-old patient with a severely compromised cornea in the form of corneal endothelial decompensation and optic atrophy, as well as severe pain after bullous keratopathy. On the first day after the EndoArt® procedure, there was already a marked decrease in corneal thickness. “In the first couple of weeks after the implantation, we learnt a lot on how the implant can be manipulated. Sometimes it can be detached from the center but we can reattach it easily. Sometimes it completely integrates into the cornea. Seventeen months post-op, the cornea is very nicely formed. And two-and-a-half years later, corneal central thickness is 547 μm,” he said.
According to Prof. Auffarth, EndoArt® provides various benefits. “The surgery is easier to perform than conventional DMEK, the implant is very forgiving in terms of intraoperative handling, and surgical techniques have been improved and fine-tuned over the years. There is no implant material degradation, and no immunosuppression therapy needed. We can effectively reduce corneal swelling and reduce the pain from bullous keratopathy,” he said.
Endothelial Keratoplasty in Eye with TASS Syndrome
Lastly, Dr. Boris Malyugin from the Russian Federation described a case of endothelial keratoplasty in a patient with toxic anterior segment syndrome (TASS).
The 66-year-old patient was present with low vision, tearing and photophobia in his left eye. Preoperative examinations showed a significant increase in central corneal thickness, which was 1,183 μm.
Surgery started with corneal epithelial removal with a blunt instrument before pupilloplasty was performed.
“Critical steps of the surgical procedure were: pupilloplasty which restores iris anatomy and function, removal of the retrocorneal membrane attached to the iris surface, and express shunt repositioning in order to restore the outflow of the aqueous humor,” he said.
On the third day post-op, VA was 0.1 (20/200) with normal intraocular pressure. The graft was attached and the central corneal thickness gradually decreased – from 713 microns on the third day to 668 microns on day 14. Two weeks post-op, VA was 0.3 (20/63). The central corneal thickness was 585 microns and the graft thickness was 114 microns.
“TASS is one of the most serious complications of cataract surgery. It should be differentiated from postoperative endophthalmitis. Endothelial keratoplasty is recommended within three months after TASS development and it provides favorable visual and anatomical outcomes,” he suggested.
Editor’s Note: The 26th European Society of Cataract & Refractive Surgeons Winter Meeting (ESCRS Winter Meeting 2022)was held virtually from February 18-20, 2022. Reporting for this story took place during the event.
