Confocal microscopy in Bowman and stromal corneal dystrophies

To use confocal microscopy to demonstrate the similarity among three autosomal-dominant corneal dystrophies and the diversity of the deposit patterns within a single dystrophy.

A prospective, comparative case series.

Twenty patients (40 eyes) from 10 families suffering from Bowman or stromal dystrophy agreed to take part: 3 with Reis-Bückler dystrophy, 12 with granular dystrophy, and 5 with lattice type-I dystrophy. Of these, nine had recurrence in their grafts or after phototherapeutic keratectomy before the confocal examination. The confocal images of affected corneas were compared with those of ten normal control eyes (ten subjects).

All patients were examined by slit-lamp biomicroscopy. Confocal microscopy was performed with Achroplan 40x/numeric aperture (NA) = 0.75 and 63x/NA = 0.9 water immersion objectives. Image analysis was used to identify the corneal epithelial and stromal deposits correlated with each disorder.

Selected images of the corneal layers were evaluated qualitatively for the size, shape, light scattering, and reflection of the deposits.

Slit-lamp biomicroscopy showed stromal involvement in all affected eyes. Confocal microscopy identified epithelial deposits in 30% of the eyes and stromal deposits in all eyes. The deposits within the epithelium were revealed more clearly with the 63x/NA = 0.9 objective (higher numeric aperture). Some of the confocal findings near the Bowman layer were common for all three dystrophies. Normal control eyes showed no epithelial or stromal deposits, either by biomicroscopy or confocal microscopy.

Confocal microscopy provides an in vivo evaluation of the deposits in the cornea, with a higher resolution than biomicroscopy. The confocal findings common to the three dystrophies may agree with previous hypotheses of the same genetic origin. It may be a useful adjunct to slit-lamp biomicroscopy, particularly when histopathologic studies cannot be performed.