Olivia L Lee

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.

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.

Glaucoma surgical considerations for PROSE lens use in patients with ocular surface disease.

PURPOSE To examine challenges of Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) treatment in patients with glaucoma drainage implants (GDI) and the surgical management of patients where both GDI and PROSE treatment are indicated. METHODS A retrospective noncomparative observational study was performed to investigate the outcomes of 7 eyes of 6 patients that required PROSE lens wear and GDI implantation. RESULTS Group A consisted of 2 cases where PROSE lens wear was problematic due to scleral surface irregularities following GDI placement. These included changes in surface morphology caused by the elevated scleral patch graft tissue adjacent to the corneal limbus in one case and the presence of two anteriorly located shunts in the other. Group B consisted of 3 eyes where the previously placed GDI led to poor lens alignment due to the proximity of the lens edge to the scleral graft. Group C consisted of 2 cases where both patients underwent placement of the GDI in the pars plana and insertion of the drainage tube 3-3.5mm from the limbus in order to facilitate PROSE lens use. The posterior location of the tube and patch allowed for proper PROSE device alignment over the ocular surface. CONCLUSIONS Surgical considerations and prior planning for GDI placement allows PROSE lens use for management of ocular surface disease. Pars plana tube placement with a posteriorly placed patch graft, instead of anterior chamber tube positioning with more anterior graft, enables adequate lens wear in scleral-lens-dependent patients.