There is a wide range of anterior-segment (AS) imaging technologies on the market today. Some AS imaging devices are better than others in anterior-segement surgeries, and surgeons must decide which options are best suited for their practices.
This article was reviewed by Dipika V. Patel, MRCOphth, PhD
A wide range of anterior-segment (AS) imaging technologies are available, but not all of these are of practical benefit for AS surgeons. Some are more useful for diagnosing, managing, and assessing the prognoses of patients undergoing keratoplasty, Dipika V. Patel, MRCOpht, PhD, pointed out.
Dr. Patel is a professor of ophthalmology, University of Auckland, Auckland, New Zealand.
Ultrasound biomicroscopy (UBM) provides a view of the AS that can be obscured by corneal opacities on slit lamp examination. The surgeon can have a robust view of the anterior chamber depth, angle, lens and anterior capsule, membranes, adhesions, and vitreous in the anterior chamber using UBM, she commented.
The disadvantage of UBM is that the patient must be supine and water immersion is usually needed (although recent models overcome these issues), both of which require patient cooperation or use of general anesthesia.
“Having the knowledge of the status of the eye behind an opaque cornea aids in planning the surgery as well as discussing the prognosis with the patient,” Dr. Patel emphasized.
With the information provided by this imaging, the surgeon can select the most appropriate surgical intervention, Dr. Patel noted. She then described a case of stromal haze that developed following implantation of a Kamra inlay (SightLife Surgical) that ultimately was removed.
At the slit-lamp, the depth of the haze could not be clearly ascertained. OCT demonstrated that the haze was maximal at the interface, including the location of the inlay, and extended both anteriorly and posteriorly to the deep stroma.
The disadvantages of AS-OCT include poor visualization of both the ciliary body and through corneal opacities.
In vivo confocal microscopy (IVCM) is useful preoperatively for looking at and differentiating among the endothelial diseases, such as bullous keratopathy, Fuchs’ endothelial dystrophy, or ICE syndrome.
Dr. Patl noted that the images may be viewed through the surgeon’s microscope on a heads-up display or an external screen.
“The availability of these images affects decision-making intraoperatively and is thought to reduce the length of the surgery,” she explained.
This technology can be applied to deep anterior lamellar keratoplasty (DALK) to evaluate the depth of the needle and dissection, the plane of big-bubble dissection, the residual stromal thickness, and to detect any microperforations.
In Descemet’s stripping automated endothelial keratoplasty (DSAEK) and Descemet’s membrane endothelial keratoplasty (DMEK), intraoperative OCT can evaluate graft-host apposition, assess the interface fluid, check the graft orientation in DMEK, and facilitate faster positioning of the graft with less manipulation.