Air Pump-Assisted Graft Centration, Graft Edge Unfolding, and Graft Uncreasing in Young Donor Graft Pre-Descemet Endothelial Keratoplasty

DMEK surgical training: An instructional guide on various wet-lab methods

Descemet membrane endothelial keratoplasty (DMEK) is a partial-thickness corneal transplantation procedure that involves selective transplantation of the Descemet membrane and endothelium. DMEK offers significant advantages over other keratoplasty techniques, such as faster visual rehabilitation, better final visual acuity due to minimal optical interface effects, lower risk of allograft rejection, and less long-term dependence on topical steroids. Despite all its advantages, DMEK has been found to be more challenging than other corneal transplantation techniques, and its steep learning curve appears to be an obstacle to its widespread use and adoption by corneal surgeons worldwide. DMEK surgical training laboratories (wet labs) provide a window of opportunity for surgeons to learn, prepare, manipulate, and deliver these grafts in a risk-free environment. Wet labs are a significant learning tool, especially for those institutions that have limited tissue availability in their local centers. We provide a step-by-step guide for preparing DMEK grafts using different techniques on human and nonhuman models with instructional videos. This article should eventually help the trainees and the educators understand the requirements for performing DMEK and conducting a DMEK wet lab and develop their skills and interests from a wide variety of available techniques.

Bilateral posterior central corneal steepening with decreased visual acuity

A 40-year-old woman was referred for the assessment of bilateral corneal opacities with gradual visual decline over the course of the past decade. Her past ocular history is significant for bilateral amblyopia and strabismus surgery in both eyes before age 5. The patient's parents were told by her childhood ophthalmologist that she had a hereditary disorder. Her systemic review was significant for anal fissure and human leukocyte antigen-B27 ankylosing spondylitis. Her past ocular record revealed corrected distance visual acuity (CDVA) of 20/80 in both eyes in 2018 with central corneal haze. On presentation, her uncorrected distance visual acuity was 20/150 in both eyes. Her CDVA was 20/100 in both eyes with manifest refraction of +0.50 -2.50 × 075 in the right eye and +5.00 -2.25 × 094 in the left eye. Corneal topography reflected keratometry of 35.75/38.97 × 171 in the right eye and 36.45/38.35 × 32 in the left eye. Central corneal thickness was 669 μm and 652 μm, respectively. External slitlamp examination revealed a central faint stromal opacity inferior to the visual axis in the right eye and a central faint stromal opacity in the left eye, and both were associated with steep posterior curvature of the cornea (Figure 1). Further findings included 0.5 corneal haze with mild guttata, normal irides, and clear lenses in both eyes. Intraocular pressure was 23 mm Hg and 26 mm Hg, respectively (Figure 2, Supplemental Figures 1 and 2, http://links.lww.com/JRS/A543). Gonioscopy was unremarkable. Dilated fundus examination revealed a 0.15 cup-to-disc ratio bilaterally, but otherwise no pertinent vitreoretinal pathologies were noted. What is the most likely diagnosis? What medical or surgical interventions would you recommend for this patient? What is the prognosis for this patient?

i-PDEK: Microscope-integrated OCT-assisted pre-Descemet endothelial keratoplasty

Four patients with pseudophakic corneal edema were subjected to pre-Descemet endothelial keratoplasty (PDEK) under the direct guidance of microscope-integrated optical coherence tomography (i-OCT). i-OCT facilitated successful type 1 big bubble formation during donor preparation, debridement of the hypertrophic epithelium, planning and placement of surgical wounds, descemetorrhexis with removal of remnant Descemet membrane tags, and identification of correct donor orientation and interface details. It was also possible to discern the stability of intraocular lens, flat iris configuration, adequate stromal hydration, and wound apposition on i-OCT. Preoperative visual acuity was counting fingers (50%), 0.78 logMAR (25%), and 1.48 logMAR (25%), whereas postoperative visual acuity was 0.6 logMAR (50%) and 0.3 logMAR (50%). At 6-months of follow-up, all grafts were clear and well attached, the mean central corneal thickness, graft size, graft thickness, and endothelial cell loss were 557.25 ± 13.45 μm, 7.75 ± 0.20 mm, 25.5 ± 2.64 μm, and 21.6 ± 0.02%, respectively. To conclude, i-OCT helped during various surgical steps of PDEK.

Use of Pressurized Air Infusion For Pre Descemet's Endothelial Keratoplasty (PDEK) - The Air Pump Assisted PDEK Technique

Purpose:

To assess the advantages offered by the air pump assisted PDEK technique that utilizes pressurized Anterior Chamber (AC) air infusion.

Methods:

Pressurized air infusion was provided through an anterior chamber maintainer connected to the fluid air exchange system of a posterior vitrectomy machine during surgery.

Results:

Pressurized air infusion within the AC helped perform Descemetorhexis, prevented bleeding during Peripheral Iridectomy (PI) and synechiolysis, prevented oozing of blood from peripheral corneal neovascularization into the AC and thus helped maintain a non-fibrinous AC environment. In addition, it helped in precise graft manipulation, centration, edge unfolding and unwrinkling after it was floated against the stroma as well as faster graft adhesion. It also prevented AC depth fluctuations during intra-cameral maneuvers and prevented intra-operative as well as post-operative graft detachment.

Conclusions:

This technique makes several steps of surgery easier and improves graft adhesion.

Recognizing and Managing Bullous Descemet Detachment Secondary to Accidental Hydroseparation During Phacoemulsification/Cataract Surgery by Relaxing Descemetotomy

PURPOSE

To report a new technique called relaxing Descemetotomy for treatment of bullous Descemet detachment (BDD) secondary to accidental hydroseparation of Descemet membrane (DM) during stromal hydration in cataract surgery.

METHODS

A clear corneal keratome entry was created close to the limbus extending inward to create a relaxing cut (ab externo relaxing Descemetotomy) on taut DM, thus creating an egress route for supra-Descemetic fluid (SDF). This was followed by pneumodescemetopexy to drain SDF internally.

RESULTS

Three patients with a history of unsuccessful pneumodescemetopexy and with planar or mildly convex separation of DM without break on anterior segment optical coherence tomography (ASOCT) underwent this procedure. All had successful reapposition of DM clinically and on ASOCT. All showed resolution of stromal edema and improved uncorrected and best-corrected visual acuity postoperatively.

CONCLUSIONS

Rarely stromal hydration performed with an irrigating cannula positioned too close to the posterior stroma can result in hydroseparation of DM creating BDD, seen intraoperatively as a fluid wave propagating across the posterior aspect of the cornea. Large folds, free mobility, and DM tear classically seen with rhegmatogenous Descemet detachment are not seen clinically or on ASOCT in BDD. Pneumodescemetopexy alone cannot resolve BDD because without a DM tear, SDF cannot evacuate. Combining relaxing Descemetotomy with pneumodescemetopexy allows SDF to drain internally and Descemet detachment to resolve. This technique has numerous advantages over classical venting incisions in terms of ease, preferable limbal location, larger incision size, absence of complications such as visual axis scars, irregular astigmatism, epithelial ingrowth, infectious keratitis, etc.