Automated Clinical Assessment of Corneal Guttae in Fuchs Endothelial Corneal Dystrophy.

PURPOSE: To describe the validation and implementation of an automated system for the detection and quantification of guttae in Fuchs endothelial corneal dystrophy (FECD). DESIGN: Observational reliability study. METHODS: Patients with FECD underwent retroillumination corneal photography, followed by determination of the distributions and sizes of corneal guttae by an automated image analysis algorithm. Performance of the automated system was assessed via (1) validation against manual guttae segmentation, (2) reproducibility studies to ensure consistency, and (3) evaluation for agreement with the Krachmer scale. It was then deployed to perform large-scale guttae assessment with anatomic subregion analysis in a batch of 40 eyes. RESULTS: Compared to manual segmentation, the automated system was reasonably accurate in identifying the correct number of guttae (mean count of 78 guttae per 1 × 1 mm test frame, overestimation: +10 per frame), but had a tendency to significantly overestimate guttae size (mean guttae size 1073 µm2, overestimation: +255 µm2). Automated measurements of guttae counts and sizes were reproducible within a 1% discrepancy range across repeat intra-eye assessments. Automated guttae counts, interguttae distances, and density of interguttae gaps lesser than 40 µm (ie, D40 density) were highly correlated with the Krachmer scale (P < .001 for all). Large-scale guttae assessment demonstrated the automated system's potential to selectively identify a region of the corneal endothelium most affected by densely packed guttae. CONCLUSIONS: Automated guttae assessment facilitates the precise identification and quantification of guttae characteristics in FECD patients. This can be used clinically as a personalized descemetorrhexis zone for Descemet stripping only and/or Descemet membrane transplantation.

Determining Subclinical Edema in Fuchs Endothelial Corneal Dystrophy: Revised Classification using Scheimpflug Tomography for Preoperative Assessment.

PURPOSE: To determine if Scheimpflug tomography can identify subclinical corneal edema in Fuchs endothelial corneal dystrophy (FECD), and to recommend a new classification of FECD for clinical practice and research. DESIGN: Cross-sectional study with follow-up of outcomes. PARTICIPANTS: Ninety-three eyes from 57 subjects with a range of severity of FECD and 74 eyes from 40 subjects with normal corneas. METHODS: Corneas were clinically assessed for FECD and corneal edema by using slit-lamp biomicroscopy, and categorized as having clinically definite edema (obvious visible edema), being suspicious for subclinical edema (possible corneal thickening without obvious edema on slit-lamp examination), or not having edema (no clinical suspicion of edema). Tomographic pachymetry and elevation maps derived from Scheimpflug images were evaluated by 3 masked observers for specific features believed to be consistent with corneal edema. FECD clinical disease course and outcomes were reviewed from the time of Scheimpflug image acquisition to the last available follow-up. MAIN OUTCOME MEASURES: Presence of tomographic features: (1) loss of parallel isopachs, (2) displacement of the thinnest point of the cornea, and (3) focal posterior corneal surface depression. Clinical outcomes included the change in central corneal thickness (CCT) and vision after endothelial keratoplasty (EK). RESULTS: The 3 specific tomographic features were all present in all FECD corneas with clinically definite edema (n = 15), in ≥81% of FECD corneas suspicious for subclinical edema (n = 16), in ≤42% of FECD corneas deemed not to have edema (n = 62), and in ≤5% of normal corneas (n = 74). Corneas suspicious for subclinical edema that subsequently underwent EK (n = 9) all had at least 2 of the tomographic features present before EK, and improvement in vision, CCT, and tomographic features after EK confirmed the presence of subclinical edema preoperatively. CONCLUSIONS: Subclinical corneal edema in FECD can be detected by Scheimpflug tomography. We recommend classifying FECD corneas as having clinically definite edema (based on slit-lamp examination), subclinical edema (based on tomographic features without clinically definite edema), or no edema (no tomographic or slit-lamp features of edema). This classification is independent of CCT and should be considered when evaluating FECD eyes for cataract surgery or EK.

Retroillumination Photography Analysis Enhances Clinical Definition of Severe Fuchs Corneal Dystrophy.

PURPOSE: Retroillumination photography analysis (RPA) provides an objective assessment of the number and distribution of guttae in Fuchs corneal dystrophy. Here, we assess its correlation with clinical grading using slit-lamp biomicroscopy across varying levels of severity. METHODS: Retroillumination photographs were conducted for 95 affected corneas with slit-lamp flash photography after pupillary dilation. Individual guttae were counted manually and the position of individual points recorded. Clinical grading using the Krachmer scale was documented for each eye during examination, and regression analyses were performed to identify the strength of association with number of guttae. We assessed range at each stage of clinical grading and used the Mann-Whitney U test to assess whether clinical grading levels demonstrated successively higher numbers of guttae. RESULTS: Krachmer score ranged from 1 to 5, with mean of 2.6. Mean numbers of guttae at each level of severity were 289 (1+), 999 (2+), 2669 (3+), 5474 (4+), and 7133 (5+). Each stage demonstrated significantly higher numbers of guttae than its preceding level except from 4+ to 5+ (P = 0.30), consistent with the definition of 4+ as the highest level defined by the presence of guttae. Higher levels of clinical grading were associated with larger ranges of guttae (P < 0.01). A linear regression model resulted in a strong fit between RPA and Krachmer score (r = 0.81). CONCLUSIONS: In this largest study of RPA data and comparison with subjective clinical grading of Fuchs dystrophy severity, RPA correlates strongly and demonstrates enhanced definition of severity at advanced stages of disease.

Corneal nerve alterations in different stages of Fuchs' endothelial corneal dystrophy: an in vivo confocal microscopy study.

PURPOSE: To analyze potential alterations in corneal nerve morphology and function in different stages of Fuchs' endothelial corneal dystrophy (FECD). METHODS: Thirty eyes with FECD underwent in vivo confocal microscopy using the Heidelberg Retina Tomograph II (HRT II; Heidelberg Engineering, Heidelberg, Germany) and the Rostock Cornea Module (RCM) to quantify the morphology of the central subbasal corneal nerve plexus (total nerve length, total nerve number, number of main nerve trunks, number of nerve branches) as well as esthesiometry (using the Cochet-Bonnet esthesiometer) of the central cornea to determine central corneal sensation as a measure of nerve function. Findings were correlated with an age-matched control group of 30 healthy individuals. Comparisons to biomicroscopical stage of FECD, visual acuity and central corneal thickness were performed using Spearman correlation. RESULTS: Depending on slit-lamp examination, all 30 eyes were classified into FECD stage 1-4 (stage 1: six eyes; stage 2: 15 eyes; stage 3: six eyes; stage 4: three eyes). Total nerve length (ρ = -0.8, p < 0.001), total nerve number (ρ = -0.7, p < 0.001), number of main nerve trunks (ρ = -0.6, p < 0.001), and number of nerve branches (ρ = -0.7, p < 0.001) decreased significantly with increasing FECD stages. Comparing to the visual acuity, significant positive correlations were found for total nerve length (ρ = 0.5, p = 0.012), total nerve number (ρ = 0.5, p = 0.005), number of main nerve trunks (ρ = 0.4, p = 0.017), and number of nerve branches (ρ = 0.5, p = 0.009). With central corneal thickness, there were significant inverse correlations for total nerve length (ρ = -0.6, p = 0.001), total nerve number (ρ = -0.5, p = 0.012), number of main nerve trunks (ρ = -0.4, p = 0.015), and number of nerve branches (ρ = -0.4, p = 0.017). Central corneal sensation was full in all FECD stage 1, stage 2 and stage 3 eyes, but mildly reduced in FECD stage 4 eyes. CONCLUSIONS: Increasing severity of Fuchs' endothelial corneal dystrophy (FECD) is concurrent with marked attenuation of the density, as well as mild diminishment of the function, of the subbasal corneal nerve plexus in late stage of the disease.

Relationship of Fuchs endothelial corneal dystrophy severity to central corneal thickness.

OBJECTIVE: To define the relationship between Fuchs endothelial corneal dystrophy (FECD) severity and central corneal thickness (CCT). METHODS: We examined 1610 eyes from a subset of index cases, family members, and unrelated control subjects with normal corneas from the FECD Genetics Multi-Center Study. To estimate the association between FECD severity grade (7-point severity scale based on guttae confluence) and CCT measured by ultrasonographic pachymetry, a multivariable model was used that adjusted for eye, age, race, sex, history of glaucoma or ocular hypertension, diabetes mellitus, contact lens wear, intraocular pressure, and familial relationship to the index case. An interaction between FECD severity grade and edema (stromal or epithelial) on slitlamp examination findings was used to investigate whether the effect of FECD severity grade on CCT differed between those with and without edema. RESULTS: Average CCT was thicker in index cases for all FECD grades compared with unaffected controls (P ≤ .003) and in affected family members with an FECD grade of 4 or greater compared with unaffected family members (P ≤ .04). Similar results were observed for subjects without edema. Average CCT of index cases was greater than that of affected family members with grades 4, 5, and 6 FECD (P ≤ .02). Intraocular pressure was also associated with CCT (P = .01). CONCLUSIONS: An increase in CCT occurs with increasing severity of FECD, including at lower FECD grades in which clinically observable edema is not present. Monitoring CCT changes serially could be a more sensitive measure of disease progression with surgical therapeutic implications.

Postoperative visual acuity in patients with fuchs dystrophy undergoing descemet membrane-stripping automated endothelial keratoplasty: correlation with the severity of histologic changes.

OBJECTIVE: To investigate a correlation between the severity of histologic changes of the Descemet membrane in patients with Fuchs endothelial dystrophy and the best-corrected visual acuity (VA) after Descemet membrane-stripping automated endothelial keratoplasty (DSAEK). METHODS: In a retrospective study design, we created a histologic grading system based on common characteristics observed histologically among 92 DSAEK specimens sent to the University of Wisconsin Eye Pathology Laboratory with a clinical diagnosis of Fuchs dystrophy from 3 separate corneal surgeons. Cases were graded as mild, moderate, or severe on the basis of guttae dispersion, presence of a laminated Descemet membrane, presence of embedded guttae, and density of guttae. Regression models were built to study the relationship among preoperative VA, histologic findings, and best-corrected VA 6 months and 1 and 2 years after DSAEK. RESULTS: No correlation was found between the severity of histologic changes of Descemet membrane and preoperative VA. However, a correlation was noted between the preoperative and final VA. Cases with a laminated Descemet membrane but no embedded guttae (n = 8) appeared to be less responsive to DSAEK. Otherwise, the severity of histologic changes of Descemet membrane observed in patients with Fuchs corneal dystrophy after DSAEK did not show a statistically significant correlation with final VA. CONCLUSIONS: Our analysis fails to show an inverse relationship between the severity of histologic changes of the Descemet membrane and the best-corrected VA of at least 20/40 after DSAEK for Fuchs endothelial dystrophy. However, in a subset of patients with Fuchs dystrophy who develop a laminated Descemet membrane without embedded guttae, the visual recovery after DSAEK is less than expected. The laminated architecture of Descemet membrane without embedded guttae may facilitate separation between the membrane layers and, thus, incomplete removal of the recipient's Descemet membrane during DSAEK, which may then limit the postoperative visual outcome.

Mathematical projection model of visual loss due to fuchs corneal dystrophy.

PURPOSE. To devise a mathematical disease classification model for eyes with primary guttata cornea, on the bases of endothelial loss trajectory and probability of advanced disease. METHODS. A series of 1971 patients (3281 eyes), some with and some without guttata corneas, undergoing specular microscopy were retrospectively reviewed. The eyes were classified into four stages; stage 0, without guttae; 1, guttata cornea without edema; 2, mild Fuchs' corneal dystrophy (FCD); and 3, severe FCD, according to clinical records, and patient age and corneal endothelial cell density (ECD) were plotted. Nonparametric density smoothing was used to create a contour map, and a best-fit curve for ECD loss was calculated. The relation between ECD decrease rate and the stages were evaluated. RESULTS. Endothelial decrease rate in stage 0 was 0.44%/year, which was compatible with that of normal eyes reported in previous studies. Decrease rates of stages 1, 2, and 3 were 0.81%, 2.65%, and 3.08%/ year, respectively. The age-ECD loss curves of 1.40%/year (ECO(1.4)) and 2.00%/year (ECO(2.0)) further divided stage 1 into three subgroups; stage 1a, asymptomatic guttata cornea; 1b, borderline guttata cornea; and 1c, pre-FCD. The ECO(2.0) cutoff line differentiated eyes with FCD from those without edema with a sensitivity and specificity of >90%. Stage 1c eyes were below ECO(2.0) and had a decrease rate as high as FCD. CONCLUSIONS. This mathematical model can be used to predict the prognosis of patients with primary guttata cornea.