Corneal Interface Morphology After Descemet Corneal Interface Morphology After Descemet Stripping Endothelial Keratoplasty by In Vivo Stripping Endothelial Keratoplasty by In Vivo

Confocal MicroscopyConfocal Microscopy

Pawan Prasher, MDPawan Prasher, MD Orkun Muftuoglu, MDOrkun Muftuoglu, MDMarvin L. Hsiao, MDMarvin L. Hsiao, MD

W Matthew Petroll, Ph DW Matthew Petroll, Ph DR. Wayne Bowman, MDR. Wayne Bowman, MDJames P. McCulley, MDJames P. McCulley, MDV. Vinod Mootha, MDV. Vinod Mootha, MD

University of Texas Southwestern Medical Center at Dallas, TexasUniversity of Texas Southwestern Medical Center at Dallas, Texas

IntroductionIntroduction Descemet stripping endothelial keratoplasty (DSEK) is Descemet stripping endothelial keratoplasty (DSEK) is

a novel technique that allows selective replacement of a novel technique that allows selective replacement of dysfunctional corneal endothelium.dysfunctional corneal endothelium.

Despite favorable visual outcomes, fewer patients than Despite favorable visual outcomes, fewer patients than expected achieve best corrected visual acuity (BCVA) expected achieve best corrected visual acuity (BCVA) of 20/20. of 20/20.

The probable factors limiting vision include interface The probable factors limiting vision include interface (IF) haze, increased corneal thickness, subepithelial (IF) haze, increased corneal thickness, subepithelial scarring,scarring,11and anatomical changes in the posterior and anatomical changes in the posterior corneal surface.corneal surface.

PurposePurpose To study interface (IF) morphology by confocal To study interface (IF) morphology by confocal

microscopy in patients undergoing DSEK for corneal microscopy in patients undergoing DSEK for corneal edema secondary to corneal endothelial cell edema secondary to corneal endothelial cell dysfunction dysfunction

Ten eyes of 10 patients with no associated ocular morbidity Ten eyes of 10 patients with no associated ocular morbidity were assessed at 6 months post-op after DSEK surgery were assessed at 6 months post-op after DSEK surgery

All eyes underwent clinical examination, confocal All eyes underwent clinical examination, confocal microscopy and Pentacam densitometry measurementmicroscopy and Pentacam densitometry measurement

Materials and MethodsMaterials and Methods

ResultsResults Mean age was 63.3+/-8.4 yearsMean age was 63.3+/-8.4 years No cornea had clinically significant IF haze on slit lamp examinationNo cornea had clinically significant IF haze on slit lamp examination BCVA ranged from 20/20 to 20/50BCVA ranged from 20/20 to 20/50 On confocal microscopy, IF was indiscernible in 2/10 casesOn confocal microscopy, IF was indiscernible in 2/10 cases IF was characterized by highly reflective particles in other (8/10) IF was characterized by highly reflective particles in other (8/10)

casescases No significant keratocyte activation was seen at IF in any caseNo significant keratocyte activation was seen at IF in any case The mean density of IF particles was 30.25±25.45 particles/mmThe mean density of IF particles was 30.25±25.45 particles/mm2 2

The mean depth of IF was 516.86±56.82µm and mean thickness of The mean depth of IF was 516.86±56.82µm and mean thickness of the endothelial graft was 128.26±30.75µm the endothelial graft was 128.26±30.75µm

The mean measured IF reflectivity was 90.87±52.29 confocal back The mean measured IF reflectivity was 90.87±52.29 confocal back scatter units (CBU) which was significantly less compared to scatter units (CBU) which was significantly less compared to subepithelial reflectivity of 447±350.3 CBU (p=0.005) subepithelial reflectivity of 447±350.3 CBU (p=0.005)

Significant keratocyte activation with high reflectivity was seen in Significant keratocyte activation with high reflectivity was seen in subepithelium or superficial stroma in 7/10 casessubepithelium or superficial stroma in 7/10 cases

Representative images of IF showing highly Representative images of IF showing highly reflective particles of varying dimensionsreflective particles of varying dimensions

Representative images of quiescent stroma Representative images of quiescent stroma without IF peak or particleswithout IF peak or particles

Representative images of keratocyte activation and Representative images of keratocyte activation and increased reflectivity in anterior stromaincreased reflectivity in anterior stroma

Representative Pentacam images showing Representative Pentacam images showing characteristic peaks and particles at the level of IF characteristic peaks and particles at the level of IF

Peak corneal density was seen in anterior stroma in all casesPeak corneal density was seen in anterior stroma in all casesIF particles were observed in 6/10 casesIF particles were observed in 6/10 cases

Representative Pentacam images showing homogenous Representative Pentacam images showing homogenous stroma without peaks or particles at the level of IFstroma without peaks or particles at the level of IF

The mean corneal density at the anterior stroma (41.53±12.61) was The mean corneal density at the anterior stroma (41.53±12.61) was significantly higher than that of measured at the IF(26.38±7.33) (p=0.004).significantly higher than that of measured at the IF(26.38±7.33) (p=0.004).

DiscussionDiscussion In vivo confocal microscopy has been widely used for the in vivo In vivo confocal microscopy has been widely used for the in vivo

microscopic imaging of healthy and pathologic corneas, including microscopic imaging of healthy and pathologic corneas, including after refractive surgery and lamellar transplants.after refractive surgery and lamellar transplants.22

Presence of reflective particles is one of the most consistent findings Presence of reflective particles is one of the most consistent findings in studies involving confocal microscopy of the IF.in studies involving confocal microscopy of the IF.

The exact nature and clinical consequences of IF particles are largely The exact nature and clinical consequences of IF particles are largely unknown. Various speculated sources include biologic debris from unknown. Various speculated sources include biologic debris from the ocular surface, powder from surgical gloves, remnants from the ocular surface, powder from surgical gloves, remnants from industrial processing of the blade, and metal fragments from the steel industrial processing of the blade, and metal fragments from the steel blade and small plastic fragments generated by the metal and plastic blade and small plastic fragments generated by the metal and plastic interaction inside the oscillating microkeratome.interaction inside the oscillating microkeratome.3,43,4

Absence of significant haze or keratocyte activation after DSEK can Absence of significant haze or keratocyte activation after DSEK can be attributed to smoother IFs resulting from Descemet stripping in the be attributed to smoother IFs resulting from Descemet stripping in the host and microkeratome cut in the donor.host and microkeratome cut in the donor.

The measurements of significantly higher reflectivity (CBU) in the The measurements of significantly higher reflectivity (CBU) in the anterior stroma as compared to IF is consistent with previously anterior stroma as compared to IF is consistent with previously reported findings in other types of posterior lamellar transplants,reported findings in other types of posterior lamellar transplants,4 4 and and may be attributed to preoperative subepithelial fibrosis.may be attributed to preoperative subepithelial fibrosis.

ConclusionsConclusions The corneal stroma appears quiescent at the level of The corneal stroma appears quiescent at the level of

DSEK IF with minimal or no keratocyte activation. DSEK IF with minimal or no keratocyte activation. In the anterior stroma, confocal microscopy showed In the anterior stroma, confocal microscopy showed

increased reflectivity and Pentacam showed peak increased reflectivity and Pentacam showed peak corneal density likely related to pre-operative corneal density likely related to pre-operative subepithelial fibrosis subepithelial fibrosis

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Abstract 4715.Abstract 4715.