Abstract
Backgroud: Previous studies of internal graft-host malappositions have not dealt with the precise ways in which each malapposition affected post-penetrating keratoplasty (post-PK) visual outcomes. In this study, we reviewed our post-PK and post-deep anterior lamellar keratoplasty (post-DALK) keratoconic patients and used anterior segment optical coherence tomography (AS-OCT) to evaluate the correlations between graft-host interface (GHI) characteristics and visual outcomes.
Methods: Novel GHI metrics included: mean graft-host touch (GHT), total prevalence of malapposition proportion (Pm), frequency of apposition (F), size of malapposition (Sm), junctional graft thickness (Tg), and the absolute value of difference between Tg and Th (|Tg-Th|). We connected the external and internal junction points of GHI (GHT) and drew a straight line through the central point, perpendicular to both sides of the cornea. Tg and Th were the thicknesses at cross-points 1 mm away from the meeting point on the external side of the graft and host, respectively. Correlations between GHI metrics and postsurgical visual outcomes [ logarithm of minimum angle of resolution best-corrected visual acuity (logMAR BCVA), spherical equivalent diopter (SE), diopter of spherical power (DS), diopter of cylindrical power (DC) and keratometric astigmatism (Astig value)] were evaluated for 45 patients (one eye each).
Results: 22 post-PK and 23 post-DALK keratoconic patients were enrolled. Compared with the regular-apposition results, GHT was decreased in step and gape patterns, and increased in hill and tag patterns. SE increased by 6.851, 5.428 and 5.164 times for every 1% increase in: F (step) [b=6.851; 95% Confidence interval (CI)=2.975-10.727; P=0.001]; F (graft step) [b=5.428; 95% CI=1.685-9.171; P=0.005]; and Pm [b=5.164; 95%CI=0.913-9.146; P=0.018], respectively. SE increased by 0.031 times for every 1-μm increment of |Tg-Th| [b=0.031; 95% CI=0.009-0.054; P=0.007]. LogMAR BCVA increased by 0.001 times for every 1-μm increment of both GHT [b=0.001; 95% CI=0-0.002; P=0.030]. and Tg [b=0.001; 95% CI=0.001-0.002; P=0.001]. Astig value increased by 0.017 times for 1-μm increment of Sm [b=0.017; 95% CI=0-0.033; P=0.047].
Conclusion: This investigation of GHI characteristics suggests explanations for varied ametropia in keratoconic eyes and has potential significance as a reference for promoting pre-surgical planning and technology for corneal transplantation.
Anterior segment optical coherence tomography findings after penetrating keratoplasty
