Abstract
Purpose: :
To determine if the population of goblet cells (GC) and filled goblet cells changes in the conjunctiva of individuals who develop dry eye after laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK).
Methods: :
Pre- and post-op tear film status was evaluated by slit lamp biomicroscopy, Schirmer test, tear breakup time and McMonnies DE questionnaire. Patients who developed clinically significant DE were included for this analysis. Impression cytology samples (ICS) were taken from the superior and temporal conjunctivae pre- and at 1W, 1M and 3M post-op. ICS on membranes were transferred to glass slides and stained with anti cytokeratin-7 (K7) to identify GC bodies; Helix pomatia agglutinin (HPA) for GC secretory product, and DAPI for cell nuclei. Five random fields were counted for each sample. Total cell number was determined by counting DAPI stained nuclei; unfilled GC number by K7 positive cells (no HPA), and filled GC by K7 cells with HPA. Statistical analyses were performed using student’s t-test.
Results: :
10 post-op DE patients were studied [5 LASIK, (3M, 2 F, average age 28.4y); 5 PRK (3M, 2F, average age 28.4 y)]. The average number of GC per patient was significantly different between PRK (72.5±11.8 cells) and LASIK (169.5±36 cells). The number of cells significantly declined at 1W in both PRK (47.3±17.9 cells) and LASIK (63.8±17.9 cells). At 3M, the number of cells had returned to pre-op levels. The percentage of total GC (filled plus unfilled) significantly decreased at 1W in both PRK (21.2±6.7%) and LASIK (24.3±6.7%) when compared to their respective pre-op levels of 31.1±6.5% and 50.6±8.5%, but recovered at 3M. For PRK, when the total number of GC was set to 100%, the percentage of filled GC significantly increased at 1W (59±13%) and 1M (76.9±7.4) post- compared to pre-op (42.6±11.9%) and began to recover at 3M. LASIK induced a significant increase in filled GC at 1W (55±12%) and 1M (60.5±13%) post-op compared to pre-op (23.8±8.5%) and began to return to the pre-op levels.
Conclusions: :
We conclude that in individuals who develop dry eye after refractive surgery, goblet cells are sensitive to stress and are easily lost. The remaining goblet cells are predominately filled goblet cells indicating that neural regulation of goblet cell secretion is disregulated but begins to recover at 3 mo.
Clinical Trial: :
www.clinicaltrials.gov NCT00411827
Keywords: cornea: tears/tear film/dry eye • conjunctiva • refractive surgery: comparative studies