In vivo evaluation of DSAEK interface with scanning-laser confocal microscopy

Evaluation of interface reflectivity and corneal aberrations following Descemet's stripping automated endothelial keratoplasty

PURPOSE:

This study aims to evaluate visual outcome after Descemet's membrane stripping automated endothelial keratoplasty (DSAEK) and relate to interface and corneal higher-order aberrations (HOAs).

MATERIALS AND METHODS:

We enrolled 16 eyes of 16 patients (eight males and eight females) in this interventional case series and followed DSAEK operation for about two to 20 months. OCULUS Pentacam, as well as other ophthalmic evaluations in follow-up visits, examined interface reflectivity and HOAs. Statistical relations were analyzed.

RESULTS:

There was statistically significant correlation between interface reflectivity and best corrected visual acuity (BCVA) (r = 0.56, P = 0.021). Pachymetry (central corneal thickness) and BCVA had a moderate correlation (r = 0.6, P = 0.013). There was no statistically significant correlation between pachymetry and follow-up time (r = −0.36, P = 0.16). Negative correlation between follow-up and interface reflectivity was also not statistically significant (r = −0.24, P = 0.35). Coma had a significant correlation with BCVA in cornea and cornea front maps (r = 0.74, P = 0.009 and r = 0.71, P = 0.013, respectively).

CONCLUSION:

Significant correlation between interface reflectivity and BSCVA was found, and anterior corneal HOAs are significantly higher than posterior HOAs.

Descemet stripping automated endothelial keratoplasty in Fuchs' corneal endothelial dystrophy: anterior segment optical coherence tomography and in vivo confocal microscopy analysis

Background

To evaluate the in vivo corneal changes using in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS-OCT) in patients with Fuchs’ dystrophy who underwent Descemet stripping automated endothelial keratoplasty (DSAEK) and the relationship between these changes and the postoperative visual recovery up to 1-year follow-up.

Methods

Before DSAEK and 1 day, 3, 6 and 12 months after surgery 31 patients (39 pseudophakic eyes) underwent a complete ophthalmological evaluation including best corrected visual acuity (BCVA), IVCM (subepithelial haze, interface haze, graft thickness) and AS-OCT (graft thickness).

Results

Graft thickness measurements by AS-OCT were strongly correlated to those obtained using IVCM at every follow-up stage (intraclass correlation coefficient = 0.95 to 0.97 between 3 and 12 months, P < 0.001 for all coefficients). No correlation between BCVA and graft thickness measured by AS-OCT at any follow-up stage was found, while at 3 and 6 postoperative months the correlations between BCVA and preoperative subepithelial haze (r = 0.61, P < 0.001 and r = 0.46, P = 0.002), interface haze (r = 0.51, P < 0.001 and r = 0.46, P = 0.003), postoperative subepithelial haze (r = 0.43, P = 0.004 and r = 0.39, P = 0.001) were significant.

Conclusions

The study confirmed corneal subepithelial haze and interface haze as important factors limiting visual acuity after DSAEK, while graft thickness was not related to BCVA.

Anterior-segment optical coherence tomography investigation of corneal deturgescence and epithelial remodeling after DSAEK

PURPOSE

The aim of this study was to evaluate via Fourier-domain anterior-segment optical coherence tomography 3-dimensional corneal, epithelial, and graft thickness changes after Descemet stripping automated endothelial keratoplasty (DSAEK).

METHODS

Sixteen eyes were investigated preoperatively and up to 6 months postoperatively for preoperative and postoperative central corneal thickness (CCT), minimum corneal thickness, central graft thickness (CGT), and for epithelial topographic thickness variability. An age-matched and gender-matched control group of 32 healthy eyes was used for comparison.

RESULTS

In the DSAEK group, the preoperative CCT was 582.32 ± 45.24 (550-615) μm. One-month postoperatively, the CCT was 736.26 ± 34.52 (713-771) μm, and the CGT was 210.42 ± 34.52 (145-243) μm. Three months postoperatively, the CCT was 641.39 ± 38.75 (569-684) μm, and the CGT was 171.23 ± 27.54 (119-185) μm. The preoperative center epithelial thickness was 55.74 ± 9.29 (45-74) μm, the minimum was 32.53 ± 14.30 (13-53) μm, the maximum was 76.00 ± 11.32 (64-105) μm, and the topographic thickness variability was 10.84 ± 4.09 (5.90-18.80) μm. Three months postoperatively, the center epithelial thickness was 47.21 ± 5.45 (43-56) μm, the minimum was 35.11 ± 4.70 (30-41) μm, the maximum was 58.11 ± 6.51 (49-65) μm, and the topographic variability was 4.77 ± 1.48 (2.90-6.50) μm. The average differences were -8.53, +4.53, and -17.89 μm for the center, minimum, and maximum (P < 0.001, <0.001, and <0.001). Similar results were obtained 3 and 6 months postoperatively.

CONCLUSIONS

We present a near-term postoperative investigation of the corneal and epithelial thickness changes after DSAEK for bullous keratopathy, by in vivo, clinical anterior-segment optical coherence tomography. Epithelial thickness recovery and normalization and corneal deturgescence were noted as early as in the first postoperative month.

Post-DSAEK optical changes: a comprehensive prospective analysis on the role of ocular wavefront aberrations, haze, and corneal thickness

PURPOSE

The aim was to assess the visual impact of ocular wavefront aberrations, corneal thickness, and corneal light scatter prospectively after performing a Descemet stripping automated endothelial keratoplasty (DSAEK) in humans.

METHODS

Data were obtained prospectively from 20 eyes preoperatively and at 1, 3, 6, and 12 months post-DSAEK. At each visit, the best spectacle-corrected visual acuity and visual acuity with glare (brightness acuity testing) were recorded, and ocular wavefront measurements and corneal optical coherence tomography (OCT) were performed. The magnitude and the sign of individual Zernike terms [higher-order aberrations (HOAs)] were determined. Epithelial, host stromal, donor stromal, and total corneal thicknesses were quantified. The brightness and intensity profiles of OCT images were generated to quantify light scatter in the whole cornea, subepithelial region, anterior and posterior host stroma, interface, and donor stroma.

RESULTS

The mean best spectacle-corrected visual acuity and glare disability at low light levels improved from 1 to 12 months post-DSAEK. All corneal thicknesses and ocular lower-order aberrations and HOAs were found to be stable from 1 to 12 months, whereas total corneal, host stromal, and interface brightness intensities decreased significantly over the same period. A repeated measures analysis of variance performed across the follow-up period revealed that the change in scatter, but not the change in the HOAs, could account for the variability occurring in the acuity from 1 to 12 months post-DSAEK.

CONCLUSIONS

Although ocular HOAs and scatter are both elevated over normal values post-DSAEK, our results demonstrate that the improvements in visual performance occurring over the first year post-DSAEK are associated with decreasing light scatter. In contrast, there were no significant changes in the ocular HOAs during this time. Because corneal light scatter decreased between 1 and 12 months despite there being stable corneal thicknesses over the same period, we conclude that factors that induced light scatter, other than tissue thickness or swelling (corneal edema), significantly impacted the visual improvements that occurred over time post-DSAEK. A better understanding of the cellular and extracellular matrix changes of the subepithelial region and interface, incurred by the surgical creation of a lamellar host-graft interface, and the subsequent healing of these tissues, is warranted.

Keratocyte apoptosis and not myofibroblast differentiation mark the graft/host interface at early time-points post-DSAEK in a cat model

PURPOSE

To evaluate myofibroblast differentiation as an etiology of haze at the graft-host interface in a cat model of Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK).

METHODS

DSAEK was performed on 10 eyes of 5 adult domestic short-hair cats. In vivo corneal imaging with slit lamp, confocal, and optical coherence tomography (OCT) were performed twice weekly. Cats were sacrificed and corneas harvested 4 hours, and 2, 4, 6, and 9 days post-DSAEK. Corneal sections were stained with the TUNEL method and immunohistochemistry was performed for α-smooth muscle actin (α-SMA) and fibronectin with DAPI counterstain.

RESULTS

At all in vivo imaging time-points, corneal OCT revealed an increase in backscatter of light and confocal imaging revealed an acellular zone at the graft-host interface. At all post-mortem time-points, immunohistochemistry revealed a complete absence of α-SMA staining at the graft-host interface. At 4 hours, extracellular fibronectin staining was identified along the graft-host interface and both fibronectin and TUNEL assay were positive within adjacent cells extending into the host stroma. By day 2, fibronectin and TUNEL staining diminished and a distinct acellular zone was present in the region of previously TUNEL-positive cells.

CONCLUSIONS

OCT imaging consistently showed increased reflectivity at the graft-host interface in cat corneas in the days post-DSAEK. This was not associated with myofibroblast differentiation at the graft-host interface, but rather with apoptosis and the development of a subsequent acellular zone. The roles of extracellular matrix changes and keratocyte cell death and repopulation should be investigated further as potential contributors to the interface optical changes.