“Studio mediante Citofluorometria a flusso delle alterazioni della superficie oculare indotte dal trattamento topico con analoghi delle prostaglandine”

Purpose: To study ocular surface changes induced by topical treatment with prostaglandin analogs containing benzalkonium chloride (BAC ). Methods: Fifteen patients (15 males; mean age: 43,6 ± 8,8 years) with unilateral ocular hypertension (intraocular pressure, IOP >20mmHg) that never undergone therapy were included in the study. All patients were treated with Latanoprost containing BAC in ocular hypertension affected eye and received BAC only in the contralateral eye. Control group consisted of 15 rights eyes of healthy volunteers. Schirmer test, tear Break-up time (BUT ) and cytofluorimetric analysis to detect the expression Class II histocompatibility antigen, HLA -DR were performed in all the patients before treatment (T0) and after 3 months (T3). Results: Schirmer and BUT test mean values at time T0 were similar in all groups, and they were lower at the time T3 in treated groups (P<0,001). The cytofluorimetric analysis at T0 showed a lack of expression of HLA -DR molecules in all the group, while only treated patients at the time T3 showed HLA -DR molecules in conjunctival cells. The average percentage of HLA -DR molecules expressed in eyes treated with BAC was greater than those treated with latanoprost+BAC (45,23 ± 12,2 and 19,54 ± 5,9 respectively; P<0,001). The mean fluorescence intensity (MFI ) of conjunctival cells treated with only BAC was greater than those treated with latanoprost+BAC (46,63 ± 24,21 and 17,35 ± 15,54 respectively; P=0,008). Conclusions: The lack of expression at T0 of HLA -DR molecules in both ocular hypertension affected eye and in normal contralateral eye excludes a pathogenetic role of ocular hypertension in different expression of class II histocompatibility antigen. The BAC produces subclinical changes in tear film as confirmed by the increased expression of HLA -DR molecules after three months of use. The lower expression of HLA -DR in the eyes treated with latanoprost and BAC suggests a potential protective effect of prostaglandin analogues against BAC toxicity on conjunctival cells.