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

PURPOSE. To describe the corneal abnormalities and to measure different mod alities of corneal sensitivity in corneal lattice dystrophy type II (famili al amyloidosis, Finnish type, also known as gelsolin-related amyloidosis an d originally as Meretoja syndrome). METHODS. Twenty eyes of 20 patients were examined by in vivo confocal micro scopy and noncontact gas esthesiometry. RESULTS. Pleomorphism of, and dense deposits between or posterior to, the b asal epithelial cells were frequently observed, as well as a reduction of l ong nerve fiber bundles in the subbasal nerve plexus. The anterior stroma w as altered in most cases, with fibrosis and abnormal extracellular matrix. In 15 corneas, thick anterior and midstromal filaments, corresponding to la ttice lines, and in 11 corneas, thin undulated structures were observed. Th e average mechanical sensitivity threshold of 12 subjects was increased, an d in the remaining 8 subjects there was no response, even to the highest in tensity of stimuli used. Three patients did not respond to CO2, 11 to heat, and 2 to cold, but those patients who responded had normal thresholds. Pat ients with more long nerve fiber bundles per confocal microscopic image had better mechanical and cold sensitivity than patients with fewer nerve fibe r bundles. CONCLUSIONS. Lattice lines seem to be related to amyloid material and not t o corneal nerves. However, the subbasal nerve density appears reduced, whic h results mainly in a decrease in mechanical and, to a lesser extent, therm al sensitivity. The location of stromal filaments and undulated structures changes with increasing age.