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JAMA Ophthalmology Journal Club Slides: Thickness and Asymmetry After DSAEK
Dickman MM, Cheng YYY, Berendschot TTJM, van den Biggelaar FJHM, Nuijts RMMA MD. Effects of graft thickness and asymmetry on visual gain and aberrations after Descemet stripping automated endothelial keratoplasty. JAMA Ophthalmol. Published online April 11, 2013. doi:10.1001/jamaophthalmol.2013.73.
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Introduction
• Descemet stripping automated endothelial keratoplasty (DSAEK) has become the procedure of choice for treating corneal endothelial disease.
• The main limitation of DSAEK is the proportion of patients achieving 20/20 visual acuity despite clear postoperative corneas and otherwise healthy eyes.
• Recently, attention has been given to the contribution of higher-order aberrations (HOAs) in degrading optical quality after DSAEK.
• Thinner DSAEK grafts have recently been suggested to achieve better visual outcomes.
• Objective:
– To investigate the effects of graft thickness and asymmetry on visual gain and aberrations after DSAEK.
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• Study Design: Retrospective analysis of an interventional case series.
• Participants: Seventy-nine eyes with corneal endothelial dysfunction.
• Data Analysis: – Visual gain was defined as the difference between preoperative and
postoperative best-corrected visual acuity in logMAR equivalents.– Graft thickness was measured centrally using anterior-segment optical coherence
tomography.– Corneal topography and HOAs were measured by Scheimpflug imaging.
• Limitations: – Retrospective design.– Thickness measurements were obtained postoperatively. – Thickness measurements were limited by axial resolution of anterior-segment
optical coherence tomography (10-20 μm; Visante; Carl Zeiss Meditec).
Methods
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• Figure 1. Measures of posterior corneal (PC) asymmetry.
Methods
Asymmetry of the PC surface was calculated by fitting raw PC elevation data against a best-fitted sphere, providing a measure of donor lenticule asymmetry in the entire 4- and 6-mm central zones, analogous to a 3-dimensional graft profile composed of numerous measurements across different meridians.
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• Mean best-corrected visual acuity improved from 0.63 logMAR equivalents preoperatively to 0.25 logMAR equivalents postoperatively (P < .001).
• Mean (SD) graft thickness of the series was 97 (25) μm (range, 39-145 μm).
• Excluding patients with vision-limiting comorbidities, visual gain significantly correlated with graft thickness (r = −0.35 [P = .02]).
• This correlation was strongest among patients with pseudophakic bullous keratopathy (PBK) (r = −0.62 [P = .01]).
• Graft thickness significantly correlated with graft asymmetry in the 4-mm and6-mm zones (r = 0.32 [P = .007] and r = 0.32 [P = .006], respectively), which in turn correlated with all but spherical PC HOAs.
Results
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Results
Figure 2. Relationship between visual gain and central graft thickness, excluding eyes with vision-limiting comorbidities.
Figure 3. Relationship between visual gain and graft thickness among patients with preoperative PBK.
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Results
Figure 4. Relationship between PC asymmetry and central graft thickness.
Figure 5. Relationship between total PC HOAs and PC asymmetry.
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• In this study, thinner grafts were associated with greater visual gain in patients without vision-limiting comorbidities.
• This finding emphasizes the importance of careful patient selection when considering a more challenging DSAEK procedure using thin donor tissue.
• The correlation between graft thickness and visual gain was strongest in patients with PBK despite the worse prognosis associated with this indication.
• This finding is encouraging but should be interpreted with caution owing to the small number of patients with PBK in this series and the possibility of a selection bias, as patients with PBK were only referred for DSAEK in the absence of significant stromal scarring.
Comment
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• A significant correlation was found between graft thickness and PC asymmetry, which in turn correlated with all but spherical PC HOAs.
• This relationship may be explained by exacerbation of the donor-recipient curvature mismatch by thicker grafts, resulting in the formation of stromal folds.
• These findings may assist surgeons in choosing DSAEK graft thickness and shape, particularly in eyes with favorable visual potential.
• Further randomized trials are needed to investigate the relationship between graft thickness and visual gain after DSAEK.
Comment
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• If you have questions, please contact the corresponding author:
– Mor M. Dickman, MD, University Eye Clinic Maastricht, P. Debyelaan 25, 6202 AZ Maastricht, the Netherlands ([email protected]).
Funding/Support
• This study was supported by a grant from ZonMw, the Netherlands Organization for Health Research and Development.
Conflict of Interest Disclosures
• None reported.
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