Jianyan Huang

Comparison of Noncontact Specular and Confocal Microscopy for Evaluation of Corneal Endothelium

Purpose: To compare endothelial cell analysis obtained by noncontact specular and confocal microscopy, using the Konan NSP-9900 and Nidek ConfoScan4 systems, respectively. Methods: Three groups including 70 healthy eyes, 49 eyes with Fuchs endothelial corneal dystrophy (FECD), and 78 eyes with glaucoma were examined with both the Konan NSP-9900 specular microscope and the Nidek ConfocScan4 confocal microscope. Certified graders at the Doheny Image Reading Center compared corneal endothelial images from both instruments side by side to assess image quality. Endothelial cell density (ECD) measurements were calculated and compared using three different modalities: (1) each instruments fully automated analysis; (2) each instruments semiautomatic analysis with grader input; and (3) manual grading methods by certified grader. Results: All normal eyes yielded gradable endothelial images, and most but not all glaucomatous eyes yielded images with high enough image quality to allow grading. In addition, in corneas with severe FECD, poor image quality precluded ECD grading by specular microscopy in 20 eyes (40.8%) but in only 4 (8.2%) confocal images from the same eyes. For the gradable images, the ECD values obtained using the manual grading method from either device were comparable with no statistically significant difference (P>0.05) between specular and confocal devices. Machine-generated ECD values were significantly different from manual results, measuring greater in all cases with specular microscopy. Machine-generated ECD values from confocal microscopy also differed significantly from manual determinations, but not in a consistent direction. Semiautomatic methods for both instruments obtained clinically acceptable ECD values. Conclusions: Automatic machine-generated ECD measurements differed significantly from manual assessments of corneal endothelium by both specular and confocal microscopy, suggesting that automated results should be used with caution. But ECD values derived manually were comparable between the two devices in both normal and glaucomatous eyes, suggesting that manually graded images from the two instruments can be used interchangeably for reliable ECD measurements. Because of a higher proportion of gradable images, confocal microscopy may be superior to specular microscopy for ECD measurements in FECD.

Analysis of ocular inflammation in anterior chamber—involving uveitis using swept-source anterior segment OCT

AbstractPurposeTo evaluate the utility of swept-source (SS) optical coherence tomography (OCT) to objectively analyze the degree of anterior chamber (AC) inflammation.MethodsThirty-eight eyes of 32 patients with uveitis and 20 control eyes were enrolled. SS OCT B-scans were obtained, and the number of cells in the B-scans was counted using two methods: (1) manual grading by Point Picker plug-in of Image J (http://bigwww.epfl.ch/thevenaz/pointpicker/) and (2) automated grading by the Image J Particle Analysis algorithm (http://imagej.net/Particle_Analysis). The automated and manual AC cell counts were correlated with the Standardization of Uveitis Nomenclature score. ResultsThe average numbers of AC inflammatory cells counted by the automated method were 8 ± 4.0, 18 ± 3.0, 42 ± 14.0, 81 ± 32.0, 117 ± 57.0, and 275 ± 67.0 cells/mm2 for grades 0, 0.5 + , 1 + , 2 + , 3 + , and 4 + , respectively. For the same clinical categories, the average manual cell counts were 6 ± 4.0, 18 ± 3.0, 34 ± 14.0, 72 ± 32.0, 92 ± 43.0, and 168 ± 65.0 cells/mm2, respectively. Zero cells were detected in the AC of healthy eyes. The automated and manual methods were highly correlated (R = 0.98, p < 0.001) and showed good correlation with the clinical grading (R = 0.88, p < 0.001). A mean AC particle size of 117.4 ± 108.8 μm was obtained by the automated method.ConclusionsQuantification of the AC cells imaged by SS AS-OCT shows good correlation with categorical clinical severity assessments in uveitis eyes. This approach may provide a more objective method for monitoring uveitis and response to uveitis therapy.

Comparison of manual & automated analysis methods for corneal endothelial cell density measurements by specular microscopy

Purpose To determine the reliability of corneal endothelial cell density (ECD) obtained by automated specular microscopy versus that of validated manual methods and factors that predict such reliability. Methods Sharp central images from 94 control and 106 glaucomatous eyes were captured with Konan specular microscope NSP-9900. All images were analyzed by trained graders using Konan CellChek Software, employing the fully- and semi-automated methods as well as Center Method. Images with low cell count (input cells number <100) and/or guttata were compared with the Center and Flex-Center Methods. ECDs were compared and absolute error was used to assess variation. The effect on ECD of age, cell count, cell size, and cell size variation was evaluated. Results No significant difference was observed between the Center and Flex-Center Methods in corneas with guttata (p = 0.48) or low ECD (p = 0.11). No difference (p = 0.32) was observed in ECD of normal controls <40 yrs old between the fully-automated method and manual Center Method. However, in older controls and glaucomatous eyes, ECD was overestimated by the fully-automated method (p = 0.034) and semi-automated method (p = 0.025) as compared to manual method. Conclusion Our findings show that automated analysis significantly overestimates ECD in the eyes with high polymegathism and/or large cell size, compared to the manual method. Therefore, we discourage reliance upon the fully-automated method alone to perform specular microscopy analysis, particularly if an accurate ECD value is imperative.

Quantitative Analysis of Depth, Distribution and Density of Cysts in Acanthamoeba Keratitis using Confocal Microscopy

Purpose: To quantify the density, distribution, and depth of invasion of cysts in the corneas of eyes with acanthamoeba keratitis (AK) by in vivo confocal microscopy (IVCM) with a novel scanning pattern. Methods: The medical records of patients with AK evaluated at the Doheny Eye Center UCLA between September 2014 and July 2016 were reviewed retrospectively. Patients with clinically diagnosed AK underwent IVCM at various time points during their clinical course. Five corneal locations were scanned at each time point: the central area and 4 standard points on the peripheral cornea corresponding to temporal, nasal, inferior, and superior locations. The IVCM scans were manually graded to quantify the maximum depth of invasion and density of cysts. Results: Twenty-one eyes of 18 patients with visible cysts on IVCM were included. Mean cyst density at presentation was 214.1 ± 120.2/mm2 (range: 64–484 cells/mm2), and the average cyst depth was 164.3 ± 81.2 &mgr;m (range: 17–290 &mgr;m). In 17 eyes, the average cyst depth was 139.4 ± 68.6 &mgr;m (range: 17–245 &mgr;m), mean cyst density was 177.9 ± 99.6/mm2, and an average of 1.4 ± 1.3 quadrants was infiltrated at presentation, and reached clinical resolution with medical treatment without surgical intervention. Four eyes that ultimately underwent therapeutic penetrating keratoplasty had cysts in all 4 quadrants and deeper cyst infiltration; the average cyst depth in these corneas was 270.5 ± 17.5 &mgr;m (range: 252–290). Conclusions: Eyes with AK requiring therapeutic keratoplasty were more likely to have a deeper and more diffuse penetration of cysts in the cornea compared with those resolving with medical treatment.

Comparison of the Center and Flex-Center Methods of Corneal Endothelial Cell Analysis in the Presence of Guttae

Purpose: To compare endothelial cell analysis by the center and flex-center methods in corneas with guttae of differing severity and to determine the minimum countable cell number for using only the flex-center method. Methods: Forty-seven eyes with corneal guttae and 50 age-matched normal controls were enrolled in the study. Three images were captured in each central cornea with the noncontact specular microscope. Endothelial cell density (ECD), coefficient of variation (CV), and percentage of hexagonal cells (HEX) were analyzed by trained graders, using both center and flex-center methods. Results: Consistent ECD and HEX values were obtained in normal eyes by both methods (P > 0.05). In corneas with guttae, ECD values obtained by the center method were 2.4% higher than those obtained with the flex-center method (P < 0.001). ECD values derived by both methods disagreed only when <30 cells were identified or <20 cells were analyzed. CV values obtained by the center method were 17.1% (P < 0.001) lower than those obtained by the flex-center method. HEX values obtained with both methods (P > 0.05) agreed. Regardless of guttae density, the ECD, CV, and HEX values of 3 images of each eye were in agreement (P > 0.05). Conclusions: In corneas with guttae, both center and flex-center methods can reliably determine ECD. Although current practice recommends the center method when at least 100 cells can be counted, our study suggests that the center method can provide a reliable ECD value when there are ≥30 contiguous countable cells in a central cornea endothelial image. The flex-center method is recommended when <30 contiguous cells are identified.