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Table 1 Definitions and Measurement Methods of AS-OCT Parameters

From: Malapposition of graft-host interface after penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK): an optical coherence tomography study

Parameters

Definition

Measurement methods

Pm

Total prevalence of malapposition proportion: proportion of all malappositions in one eye (range:1/8~8/8)

Divide the number of malapposition in one eye by 8, then multiplied by 100%

F

Frequency of apposition: proportion of a certain type of apposition in one eye (range: 1/8~8/8)

Divide the total number of a type of apposition in one eye by 8, then multiplied by 100%

GHT

Mean graft-host touch: the linear distance between epithelial and endothelial surfaces of the GHI

Linear distance between the external and internal junction points of GHI

Sm

Size of malapposition: the maximum distance between malapposition and the normal DM layer

1.Gape of protrusion (hill and tag) alignment: through the vertex of protrusion or gape, draw a straight line that is perpendicular to the DM layer or tangential direction of DM layer, then record the length

2.Graft step alignment: first locate the farthest point on graft step from the host, then make a virtual extension curve from the host DM layer, and then draw a straight line that is perpendicular to the tangential direction of the curve and record the length.

Host step alignment: refer to the procedure for graft step alignment.

Tg and Th

Junctional graft thickness (Tg): graft thickness 1 mm from GHI; Junctional host thickness (Th): host thickness 1 mm from GHI

First connect the external and internal junction points of GHI and locate a central point, then draw a straight line through the point and make it perpendicular to both external and internal sides of the cornea. Calculate Tg and Th by measuring the thicknesses at cross-points 1 mm away from the meeting point on the external side of graft and host sides.

|Tg-Th|

absolute value of difference between Tg and Th

mathematical calculation

  1. DM Descemet’s membrane, GHI Graft-host interface