Corneal morphology and sensitivity in lattice dystrophy type II (familial amyloidosis, Finnish type)

To describe the corneal abnormalities and to measure different modalities of corneal sensitivity in corneal lattice dystrophy type II (familial amyloidosis, Finnish type, also known as gelsolin-related amyloidosis and originally as Meretoja syndrome).

Twenty eyes of 20 patients were examined by in vivo confocal microscopy and noncontact gas esthesiometry.

Pleomorphism of, and dense deposits between or posterior to, the basal epithelial cells were frequently observed, as well as a reduction of long nerve fiber bundles in the subbasal nerve plexus. The anterior stroma was altered in most cases, with fibrosis and abnormal extracellular matrix. In 15 corneas, thick anterior and midstromal filaments, corresponding to lattice lines, and in 11 corneas, thin undulated structures were observed. The average mechanical sensitivity threshold of 12 subjects was increased, and in the remaining 8 subjects there was no response, even to the highest intensity of stimuli used. Three patients did not respond to CO(2), 11 to heat, and 2 to cold, but those patients who responded had normal thresholds. Patients with more long nerve fiber bundles per confocal microscopic image had better mechanical and cold sensitivity than patients with fewer nerve fiber bundles.

Lattice lines seem to be related to amyloid material and not to corneal nerves. However, the subbasal nerve density appears reduced, which results mainly in a decrease in mechanical and, to a lesser extent, thermal sensitivity. The location of stromal filaments and undulated structures changes with increasing age.