Changes in Corneal Parameters after DMEK Surgery: A Swept-Source Imaging Analysis at 12-Month Follow-Up Time

Severe Corneal Flattening After Endothelial Keratoplasty: Collagen Compaction Syndrome

PURPOSE

The purpose of this study was to present a case series of patients with extreme corneal flattening after uneventful endothelial keratoplasty (EK): collagen compaction syndrome.

METHODS

Four patients (2 men, 2 women, mean age 64.8 ± 11.8 years) underwent successful EK after a period of chronic corneal edema (4-7.5 months): 3 received Descemet membrane endothelial keratoplasty after unsuccessful Descemet stripping only for Fuchs dystrophy and 1 received Descemet automated endothelial keratoplasty after prolonged pseudophakic bullous keratopathy.

RESULTS

All patients developed significant corneal flattening, affecting their vision and inducing a large hyperopic refractive outcome, best-corrected visual acuities ranging from 20/40 to 20/200.

CONCLUSIONS

Chronic corneal edema may result in severe corneal flattening after EK. Preoperative duration of stromal edema might affect the outcome of EK and should, therefore, be considered in the timing of surgery. In cases of dense focal edema, including post-Descemet stripping only surgery, rescue treatment at week 8 should be considered.

Deformable Biomechanics of DMEK Tissue Scrolls Traveling Through Narrow Lumens: The Inverse Relationships Between Fluid Velocity, Scroll Width, and Wall Contact and Their Clinical Implications for Preloading

PURPOSE

The aim of this study was to evaluate Descemet membrane endothelial keratoplasty (DMEK) scroll width and length in relation to variable velocities as the tissue transits through wide and narrow lumen glass tubes.

METHODS

Sets of DMEK tissue were processed using the Iowa Lions Eye Bank standard DMEK protocol and were passed through 2 glass tube widths at variable speeds. Two hourglass-shaped glass tubes were created, one "wide" and one "narrow." A syringe pump, valve, and pressure gauge were used to modulate tissue speed through each tube. For both tube sizes, DMEK tissue was passed through their lumens with incrementally increasing velocity and visualized with a high-speed camera at frame rates from 1000 to 8000 fps. Scroll width and length were measured using IDT Motion Studio software and digital calipers.

RESULTS

There was a significant, indirect correlation between scroll velocity and width in both the wide (R 2 = -0.98, P < 0.001) and narrow (R 2 = -0.84, P < 0.001) tubes. There was a significant, direct correlation between scroll velocity and length in both the wide (R 2 = 0.84, P < 0.001) and narrow (R 2 = 0.83, P < 0.001) tubes. The resting widths of the scrolls were 105% and 207% wider than the wide and narrow tubes, respectively. All transits recorded scroll widths that were equal to or smaller than their respective tube's internal diameter.

CONCLUSIONS

There is a significant, inverse correlation between DMEK scroll velocity and width as well as a direct correlation between scroll velocity and length, allowing DMEK scrolls to transit through a tube that is narrower than its resting width without sustained lumen wall contact.

Optical quality of the cornea after Descemet membrane endothelial keratoplasty surgery: early results from Türkiye

Background

Descemet membrane endothelial keratoplasty (DMEK) is increasingly favored in the treatment of endothelial dysfunction due to its benefits, which include swift visual rehabilitation and recovery, a relatively low rejection rate, and superior refractive stability. In this study, we examined alterations in corneal clarity among patients who underwent DMEK and correlated these densitometry findings with other optical parameters of corneal topography.

Methods

The study incorporated 35 eyes from 35 patients who had previously undergone DMEK surgery for pseudophakic bullous keratopathy at Ankara Bilkent City Hospital. The results from these patients were compared with those from a healthy control group. The preoperative and postoperative optical parameters of the patients were assessed using Pentacam Scheimpflug topography (Oculus).

Results

We observed significant decreases in corneal densitometry in the 0-2 mm and 2-6 mm zones of the anterior, posterior, central, and total layers at the sixth month postoperatively compared to the preoperative period (P<0.05). The corneal densitometry values at postoperative month 6 were elevated in all layers and zones relative to the healthy group (P<0.05). The root mean square of higher-order aberrations in postoperative period was elevated significantly (P<0.001).

Conclusions

Six months after operation, the optical quality of the cornea following DMEK surgery did not achieve the level of a healthy cornea.

Comparative Analysis of Corneal Parameters in Swept-Source Imaging between DMEK and UT-DSAEK Eyes

Background: The need to provide a comparative analysis of corneal parameter changes compared to their preoperative values between Descemet membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) patients. Methods: The study included 24 eyes after UT-DSAEK and 24 eyes after DMEK. Visual acuity, endothelial cell count (ECC), central corneal thickness (CCT), mean keratometry (MK), mean astigmatism (MA), astigmatism asymmetry (AA) and higher-order aberrations (HOAs) were assessed at baseline and 1, 3, 6 and 12 months after the surgery. Results: From the 3rd month post operation, ECC was higher in the DMEK eyes than in the UT-DSAEK eyes (p = 0.01). In a bivariate analysis that was adjusted for age, DMEK was associated with a smaller decrease in posterior MK at the 1-month (β = −0.49, p = 0.002), 3-month (β = −0.50, p < 0.001), 6-month (β = −0.58, p < 0.001) and 12-month (β = −0.49, p < 0.001) follow-up visits. There were no significant differences in changes in anterior or combined surface MK throughout the observation period. Accordingly, no significant differences in changes in MA, AA or HOAs compared to the baseline values were identified between the eyes after DMEK and UT-DSAEK at any follow-up time point. Conclusions: UT-DSAEK seemed to be an easier and safer technique than DMEK while maintaining similar outcomes regarding irregular astigmatism and total keratometry values.