Alteration in disc diameter after DSAEK

DSAEK

Takefumi YAMAGUCHI, Yoshiyuki SATAKE, Seika DEN,Kenji KONOMI, Jun SHIMAZAKI

Tokyo Dental College, Ichikawa General Hospital,Chiba, JapanAlteration in disc diameter after DSAEK

The authors have no financial interest.Introduction

Descemets stripping and automated endothelial keratoplasty (DSAEK) is treatment of first choice for bullous keratopathy. Total number of endothelial cells transplanted is important in maintaining sufficient number of endothelial cells after DSAEK. However, whether larger disc preferable remains unknown. If so, how large a disc can be safely transplanted? Herein we conducted the study on the disc structure after DSAEK.Purpose To evaluate alteration in disc diameter and structure after DSAEK. PatientsThis study comprised 15 eyes in 15 patients who underwent DSAEK at Tokyo Dental College Women: 12 eyes; Men: 3 eyes Age +/- SD: 69.3 +/-12.6 years

Causes of bullous keratopathy (no.of eyes)Laser iridotomy: 7 Cataract surgery: 5 Fuchsendothelial dystrophy: 2 Pseudoexfoliation syndrome: 1 Surgical technique (no. of eyes)DSAEK: 9 DSAEK+PEA+IOL: 5 DSAEK+TS IOL suturing: 1 (TS: transscleral)

Disc diameter8 mm: 14 (no. of eyes) 7.75 mm: 1

Graft preparation All grafts were imported from Sight Life Eye Bank (Northwest) and prepared using Barrons corneal punch during surgery.

MethodsData on disc diameter, central graft anterior chamber depth#1 and central and peripheral graft thickness were obtained using anterior segment optical coherence tomography (AS-OCT, CASIA, SS-1000, Tomey, Japan) at 1 and 3 months after DSAEK. Measurements were performed manually under refractive correction in 4 directions: horizontal, vertical, 45 and 135 degrees.Where large decentration of graft position was observed, data were excluded from study.

GDG-ACDGD: Graft diameter, G-ACD: graft anterior chamber#1 Graft anterior chamber depth (G-ACD) was defined as distance between apex of posterior surface of graft and line connecting inner graft edges.ResultsLogMARVisual acuityEndothelial cell countGraft anterior chamber(G-ACD)=1.500.19 m, Central graft thickness (CGT)=12130.1 mPeripheral graft thickness(PGT)=235101 m, Angle to angle distance (AD)=11.70.58 mmAverage disc diameterGD Disc diameter shrank in all 4 directions (mm: no. of eyes out of 11 eyes#1):0.10 < : 9 (81%)0.25 < : 7 (64%) 0.40 < : 5 (46%)#1 Number of patients on whom accurate data obtained in all 4 directions with no obstruction by lid or cilia.GD: Graft diameter(mm)OGraft center (vertical)(horizontal)O:Measurement centeroo= x (mm)(135) (45)AABBCCDDEffect of graft decentrationPossible measurement error caused by decentration from center of graft during measurement.Distance between O and O: x (mm)Largest amount of graft shrinkage in 4 directions: S (mm) = OOAS is maxim value if is 22.5 If S is below 0.10 mm, x >0.12614 mmIf S is below 0.25 mm, x > 0.3013 mmIf S is below 0.40 mm, x > 0.462751mm In measuring length and width, there is a high possibility that decentration will cause the graftto appear smaller than it actually is. Taking measurements in all four directions lowers the margin of error.Relation between GD and G-ACDGD: Graft diameter, G-ACD: graft anterior chamberGD was significantly correlated with G-ACD. (Pearsons correlation analysis).G-ACDGD

This result indicates that G-ACD /GD ratio did not change in various eyes after DSAEK, which suggests the posterior surface curvature (flat or steep) did not influence the GD.Is larger disc preferable?AdvantageMore endothelial cells can be transplanted.

DisadvantagePossible decrease in endothelial cells due to manipulation of large disc during surgery.However, there are two important PREMISES Graft size does not change after DSAEK. Endothelial cells will distribute equally throughout host and graft surface.

Slightly shrinksDiscussionEndothelial cell loss after DSAEK has been reported to be 20-50%. Area calculated from parameters of model eye Posterior corneal surface(ACD2.8 mm): approx.110 mm2 Posterior surface of disc of 8 mm: approx.55 mm2Surface area Disc diameter (2c)S=(c2+h2), c: radius, h: height, h=r-r2-c2, r: curvature of posterior corneal surface, r = 6.8 mmArea of posterior corneal surfaceDiscussionIf disc shrinks by around 0.25 mm after DSAEK, it might be possible to transplant larger disc or customize disc diameter using preoperative values of AS-OCT such as angle-to-angle distance or anterior chamber depth in each patient. (We call this AS OCT-assisted DSAEK) If endothelial cells distribute equally on host and graft cornea after DSAEK, endothelial cell loss in previous studies can not be explained based on calculation of posterior surface area. It is possible that endothelial cell privilege in DSAEK graft prevents equal redistribution of endothelial cells after DSAEK. More comprehensive and long-term evaluation, including central and peripheral endothelial cell counts, graft edge configuration and chromosome assessment in graft and host cornea, will yield invaluable information on this issue.ConclusionDisc diameter tended to shrink from 1 month after DSAEK, stabilizing at 3 months.

In some patients, large alteration in disc diameter observed, suggesting larger disc is preferable in some cases. However, postoperative endothelial cell redistribution on host and graft cornea must be evaluated in future.