Decreased corneal sensitivity and abnormal corneal nerves in Fuchs endothelial dystrophy

Abstract

Purpose: To determine corneal sensitivity and evaluate corneal nerves before and after keratoplasty for Fuchs endothelial dystrophy.

Methods: Central corneal sensitivity, measured by using a Cochet-Bonnet esthesiometer in 69 eyes before and after different keratoplasty procedures for Fuchs dystrophy, was compared with that of 35 age-matched normal corneas. Corneal nerves were qualitatively examined by confocal microscopy in 42 eyes before and after Descemet stripping endothelial keratoplasty (DSEK).

Results: Corneal sensitivity in Fuchs dystrophy (4.61 ± 1.42 cm) was lower than that of age-matched controls (5.74 ± 0.48 cm, P < 0.001). Sensitivity decreased by 1 month after DSEK (2.98 ± 2.01 cm, P < 0.001), returned to preoperative sensitivity by 24 months (4.50 ± 1.63 cm, n = 33, P = 0.99), but remained lower than controls at 36 months (4.50 ± 1.48 cm, n = 15, P < 0.001). Sensitivity at 36 months after penetrating keratoplasty (1.46 ± 1.98 cm) remained decreased compared with preoperative sensitivity (P < 0.001). Subbasal nerves appeared sparse with abnormal branching before and through 36 months after DSEK. Sensitivity was lower in corneas without visible subbasal nerves by confocal microscopy at 12 months after DSEK (P < 0.005) than in corneas with visible nerves. Stromal nerves were frequently tortuous and formed loops in Fuchs dystrophy, and this appearance persisted in some eyes at 36 months after DSEK.

Conclusion: Corneal sensitivity is decreased in Fuchs dystrophy compared with normal and remains subnormal even at 3 years after endothelial keratoplasty. Decreased sensitivity is likely to be related to loss of subbasal nerves and abnormal nerve morphology, which persist after endothelial keratoplasty.

Trial registration: ClinicalTrials.gov NCT00346138.

Figures

Figure 1. Subbasal nerve fiber bundles in a normal cornea, and before and after Descemet stripping endothelial keratoplasty (DSEK) for Fuchs dystrophy (confocal microscopy)

Top Left, Subbasal nerve fiber bundles appear as linear bright structures between the basal epithelial cells and anterior keratocytes in normal corneas; the bright, out-of-focus objects in the image represent anterior keratocyte nuclei deep to the nerves. Top Right, In Fuchs dystrophy, when the subbasal nerves were visible, they were typically finer and sparser compared to normal; the diffuse increase in reflectivity represents subepithelial haze, which might have precluded visibility of subbasal nerve fiber bundles in some eyes. Second row, Occasionally in Fuchs dystrophy, there were thickened subbasal nerve fiber bundles with abnormal branching patterns (left), and thick, stellate brightly reflective structures associated with fine and fragmented nerve fiber bundles (right). Third row, Twenty-four months after DSEK for Fuchs dystrophy, the subbasal nerve fiber bundles typically remained fine and sparse (left) and occasionally there were thickened, brightly reflective nerve branch points with abnormal branching patterns (right). Dimensions of the confocal images were 428 × 325 µm (horizontal × vertical).

Figure 2. Stromal nerve fiber bundles in a normal cornea, and before and after Descemet stripping endothelial keratoplasty (DSEK) for Fuchs dystrophy (confocal microscopy)

Top Left, Stromal nerves in normal corneas typically appear as straight brightly reflective structures, and well-defined branching points are often visible. Top right and second row, In Fuchs dystrophy, nerves often were tortuous and formed loops in the mid stroma. Frequently, the tortuous nerves were associated with brightly reflective keratocyte nuclei. Third row, After DSEK, the tortuous nature of the stromal nerves persisted at 12 months (left) and 24 months (right) with the nerves typically appearing finer than before keratoplasty and often associated with brightly reflective keratocyte nuclei. Dimensions of the confocal images were 428 × 325 µm (horizontal × vertical), and all images were from the anterior and middle thirds of the corneal stroma.