Abstract
Purpose:
To evaluate corneal sensation and subbasal nerve plexus changes using laser in vivo confocal microscopy (IVCM) in early and late stage Fuchs endothelial corneal dystrophy (FECD).
Methods:
A prospective, cross sectional study was conducted and 33 FECD patients (33 eyes) were included. FECD patients were classified into early (without edema) and late stage (with edema). Fourteen eyes with pseudophakic bullous keratopathy (PBK) were used as positive controls (edematous cornea) and 17 normal age-matched controls eyes as negative controls. IVCM (HRT3/RCM) was performed in the central cornea. Three representative images were evaluated by masked 2 observers for density and number of subbasal nerves (NeuronJ), and presence of dendritic immune cells(DC)(ImageJ). Central corneal sensation was assessed by Cochet-Bonnet esthesiometer.
Results:
Eyes with FECD and PBK showed significantly diminished subbasal nerves, including total nerve length (11.5±1.3 and 2.8±0.7mm/mm2, respectively;p=0.001) and total number of nerves (8.8±1.1 and 2.2±0.4 n/frame;p=0.001), as compared to controls (23.3±8.1 mm/mm2 and 25.9±5.3 n/frame). Decreased nerves corresponded (R = 0.32) to diminished sensation in both FECD (4.9±0.2cm;p=0.045) and PBK (3.6±0.6;p=0.001) as compared to controls (5.9±0.04). Both early stage (n=22) and late stage FECD (n=11) showed significant reduction in total nerve density (13.1±1.4; 9.9±1.2, respectively;) and number (8.2±2.5; 6.5±2.1), compared to controls (p<0.001) but the decrease was not significant between the two groups (p=0.105). DC density was significantly increased in FECD (60.8±10.8 cells/mm2; p=0.01), but not in PBK (44.8±11.9;p=0.60) in comparison to controls (23.0±4.2). A subset of early stage FECD patients (7/22) had very high DC density (>100cells/mm2).
Conclusions:
IVCM demonstrates profound diminishment of subbasal nerves in both FECD and PBK, correlating to decreased sensation. Interestingly, even early-stage FECD patients had decreased subbasal nerves. Further, increased DC were found in patients with FECD, demonstrating subclinical inflammation. The data suggests that reduction in subbasal nerves and inflammation may potentially play a role in FECD. Additional studies are required to investigate whether subbasal nerve alterations are directly caused by decreased endothelial cell density, or potentially lead to loss of endothelial cells.
Keywords: 481 cornea: endothelium •
550 imaging/image analysis: clinical •
596 microscopy: confocal/tunneling