1. 1 Non-contact Specular Microscopy for Evaluation of Corneal Endothelium in Early Fuchs’ Endothelial Corneal Dystrophy Jianyan Huang 1, MD, PhD; Tudor Tepelus 1, PhD; Cristina Modak 1, PhD; Vikas Chopra 1,2, MD; Srinivas R Sadda 1,2, MD; Olivia L Lee 1,2, MD 1 Doheny Image Reading Center, Doheny Eye Institute, Los Angeles, California, USA; 2 Department of Ophthalmology, David Geffen School of Medicine, University of California Los Angeles. Los Angeles, USA

2. Financial Disclosure Dr. Sadda Consultant: Allergan, Genentech, Regeneron, Optos, Carl Zeiss Meditec Research Grant Support: Optos, Carl Zeiss Meditec, Allergan, Genentech Dr. Chopra Consultant: Allergan Research Grant Support: Allergan Dr. Lee Consultant: Allergan Research Grant Support: Allergan All other authors Nothing to disclose 2

3. Introduction 3 Early Fuchs endothelial corneal dystrophy (FECD) is characterized by asymmetrical, bilateral, slowly progressive formation of guttata in the absence of clinically significant corneal edema. Progression of cornea guttata proceeds from the center of the cornea and spreads to the periphery. Endothelial cell attrition rises with increasing number and size of the guttate lesions. Eventually, edema of the corneal epithelium and stroma appears, causing blurred vision. Accurately assess the cornea endothelial cell density is clinically helpful to estimate the health of the endothelium, but also can track the progression of FECD longitudinally. Specular microscopy can provide a non-invasive morphological analysis of the corneal endothelial cell layer to detect the early FECD patients and a variety of analysis programs are available to determine corneal endothelial cell density (ECD) and morphometry. The purpose of this study is to describe the use of non-contact specular microscopy to obtain accurate endothelial cell measurements with Center method or Flex Center method in the face of varying guttata density.

4. Methods 4 Using the Konan NSP 9900 specular microscope, three images of the central corneal endothelium were captured in each eye of normal control and early FECD affected eyes. All the eyes had no history of corneal or intraocular surgery, ocular trauma, keratitis or uveitis. Patient and subject information GroupAge (years)NumberGender Control61.1±15.449 eyes (25 subjects)13 female 12 male FECD60.3±14.539 eyes (24 patients)13 female 11 male

5. 5 Methods Corneal endothelial cell analysis using both the Center method and Flex Center method was performed by 2 certified graders. Measurements of ECD, coefficient of variation (CV) and hexagonality (HEX) were then calculated using Konan CellChek software. Guttata surface area in each image was quantified by ImageJ, an image analysis software. Variation in ECD values was determined based on the % error and relative standard deviation. Absolute error <5% was considered acceptable agreement. Results were expressed as means ± standard deviations. Statistical analyses were performed using SPSS ver. 13.0. Statistical methods employed include paired t test, independent t test, Spearman correlation and one way ANOVA.

6. Results 6 The mean values of endothelial parameters obtained by both Center and Flex Center methods in normal corneas and early FECD-affected corneas. Normal corneas (n=49) FECD affected corneas (n=39) P*P*FECD affected corneas Frame#1 FECD affected corneas Frame#2 FECD affected corneas Frame#3 P** Center method ECD2669±2612322±5370.0012339±5832308±6032324±5390.949 CV34±429±4<0.00129±629±5 0.398 HEX59±559±70.97357±1261±1359±100.454 Flex center method ECD2664±2612267±5830.0012275±5792264±5962267±5840.906 CV36±435±50.29735±633±634±40.638 HEX58±660±60.11259±762±1060±70.806 * Comparisons between the normal corneas and FECD affected corneas were made by paired t test. ** Comparisons among the 3 different images from the same FECD affected corneas were made by one way ANOVA.

7. Results 7 Correlation of overall guttata area with endothelial parameters in FECD-affected cornea. Spearman correlation coefficient P Center methodECD-0.3400.001 CV-0.3140.001 HEX-0.1740.069 Flex center methodECD-0.433<0.001 CV-0.1520.014 HEX-0.0550.665

8. Results 8 Agreement between Center method and Flex center method based on differences in the number (NUM) of identified cells applied to the calculation of ECD. NUMPercentage of Error ≥5% ≤ 1056.25 (9/16) 10< NUM ≤ 1525 (3/12) 15< NUM ≤ 2050 (3/6) 20< NUM ≤ 3020 (2/10) >3012.3 (9/73) Total22.2 (26/117)

9. Results 9 Frame #1 #2 #3 Three representative eyes with early FECD, showing the ungraded specular image and the same image manually graded by Center and Flex center methods. (INP: input dots by grader).

10. Conclusions 10 In early FECD, both Center and Flex center methods can be used to reliably determine ECD. ECD values are lower in FECD-affected corneas than in control eyes. The overall guttata has a negative correlation with ECD value, but is unrelated to CV and HEX.

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