Corneal Endothelial Cell Loss in Glaucoma and Glaucoma Surgery and the Utility of Management with Descemet Membrane Endothelial Keratoplasty (DMEK)

A computational fluid dynamics investigation of endothelial cell damage from glaucoma drainage devices

Glaucoma drainage devices (GDDs) are prosthetic-treatment devices for treating primary open-angle glaucoma. Despite their effectiveness in reducing intraocular pressures (IOP), endothelial cell damage (ECD) is a commonly known side-effect. There have been different hypotheses regarding the reasons for ECD with one being an induced increase in shear on the corneal wall. A computational fluid dynamics (CFD) model was used to investigate this hypothesis in silico. The Ahmed Glaucoma Valve (AGV) was selected as the subject of this study using an idealised 3D model of the anterior chamber with insertion angles and positions that are commonly used in clinical practice. It was found that a tube-cornea distance of 1.27 mm or greater does not result in a wall shear stress (WSS) above the limit where ECD could occur. Similarly, a tube-cornea angle of 45° or more was shown to be preferable. It was also found that the ECD region has an irregular shape, and the aqueous humour flow fluctuates at certain insertion angles and positions. This study shows that pathological amounts of WSS may occur as a result of certain GDD placements. Hence, it is imperative to consider the associated fluid force interactions when performing the GDD insertion procedure.

Clinical and surgical outcomes of glaucoma drainage device tube in ciliary sulcus versus anterior chamber in North Indian glaucoma patients

Purpose

To evaluate the outcome of glaucoma drainage device (GDD) insertion of tube through ciliary sulcus (CS) versus anterior chamber (AC) placement in the North Indian population.

Methods

This retrospective comparative case series included 43 patients in CS group and 24 in AC group, who underwent GDD implantation, from March 2014 to February 2020. The main outcome measures were intraocular pressure (IOP), number of anti-glaucoma medications, best corrected visual acuity (BCVA), and complications.

Results

Sixty-seven eyes of 66 patients were included in study with mean follow-up of 25.04 months (range, 12-69 months) in the CS group and 17.4 months (range, 13-28 months) in the AC group. Preoperatively the two groups were similar except for postpenetrating keratoplasty glaucoma (PPKG) and pseudophakic patients, which were higher in the CS group (P < 0.05). Both groups showed statistically insignificant difference in postoperative IOP and BCVA at last follow-up (P = 0.173, P = 0.495, respectively). Postoperative complications were similar, except for corneal decompensation which was significantly higher in the AC group (P = 0.042).

Conclusion

Our findings suggest that there was no statistically significant difference in mean IOP between the CS and AC groups at the last follow-up. CS placement of tube of GDD appears to be effective and safe technique. However, CS placement of tube resulted in lesser corneal decompensation and thus should be preferred in pseudophakic/aphakic patients, especially PPKG.

The Descemet Membrane Endothelial Keratoplasty (DMEK) "Wave Maneuver"

A novel technique for Descemet membrane endothelial keratoplasty (DMEK) graft handling and centration without the endothelium touching the posterior part of the anterior chamber (AC), is presented here. It is particularly suitable for vitrectomized eyes, deep AC, and AC intraocular lenses (ACIOLs), potentially reducing surgery time and endothelial cell loss during surgery. This retrospective interventional case series includes 27 eyes with complex ocular pathology. All utilized a “Wave maneuver” to center an early elevated graft without completing graft centration on the bottom of the AC. Successful graft attachment and centration were evaluated intra and post-operatively. Best-corrected visual acuity (BCVA), central corneal thickness (CCT), and donor endothelial cell density (ECD) were measured pre-operatively, and three and six months post-operatively. DMEK grafts were successfully attached and centered in all cases. No maneuver-related complications were observed intraoperatively. BCVA improved from a pre-operative 0.2 ± 0.63, to 0.43 ± 0.49 and 0.76 ± 0.51 at the three- and six-month follow-ups, respectively (p < 0.01). CCT decreased from a pre-operative 742 ± 118, to 546 ± 87 and 512 ± 67 at three and six months, respectively (p < 0.01). ECD decreased from 2878 ± 419 cells/mm2 to 1153 ± 466 cells/mm2 at three and six months, respectively (p < 0.01). The “Wave maneuver” may be very beneficial in DMEK cases where the AC is either very deep or the bottom of the AC is compromised. The “Wave maneuver” learning curve was brief.