Ultrastructural study of the conjunctiva in patients with keratoconjunctivitis sicca not associated with systemic disorders

Purpose. The aim of this work was to evaluate ultrastructural alterations o f the conjunctiva during the clinical course of keratoconjunctivitis sicca (KCS), and to detect its earliest and most characteristic morphological cha nges. Methods. The conjunctiva was studied in biopsies from 75 patients and 10 co ntrols. Patients were classified according to the results of the Schirmer I test, break-up time, rose Bengal staining, osmolarity and impression cytol ogy. Results. The conjunctiva in these KCS patients showed progressive hyperplas ia, hypertrophy and cellular flattening, with diminution of goblet cell den sity and microvilli. In the severe cases, the epithelial cells lost their o rganelles, and fibrous material increased. From the early phases of KCS, cl ear nuclear alterations (indentation, binucleation) were found, but pyknoti c nuclei or anucleated cells were only observed in the most severe cases. F rom the earliest stages to the most severe cases of KCS, decreases in cell membrane interdigitations were observed parallel to increases in the number and size of desmosomes. There were also increases in the number of inflamm atory cells. Alterations in blood vessels were only observed in the most se vere cases. Conclusions. Morphological studies alone were able even in the earliest pha ses of KCS, to detect the squamous metaplasia that progresses from the surf ace of the epithelium to the connective tissue. This degenerative or adapta tive cellular process was characterized mainly by marked proliferation of t he cytoskeleton and a general loss of organelles, mitochondria being the le ast affected.