Dry Eye Disease in Patients with Functioning Filtering Blebs after Trabeculectomy

Abstract

PurposeThe aim of this study was to analyze dry eye disease (DED) in patients with functioning filtering blebs and to explore the relationship between the morphology of filtering blebs and ocular surface instability.MethodsThis was a cross-sectional, case-comparison study. Seventy glaucomatous patients (70 eyes) with functioning blebs who had undergone trabeculectomy more than 6 months prior (study group) and 35 control subjects (35 eyes) (control group) were included. All subjects completed an ocular symptom questionnaire that referred to the Shihpai Eye Study. Evaluation of meibomian gland obstruction, a tear film break-up time test (TFBUT), fluorescein corneal staining and a Schirmer’s tear test were then performed. Filtering bleb morphology was analyzed using Wuerzburg bleb classification scoring criteria in the study group. The presence of DED was defined as the concomitant presence of TFBUT <10 seconds and the presence of superficial punctate keratitis.ResultsThe patients with functioning blebs presented higher corneal staining scores (P = 0.012) and lower TFBUT values (P = 0.043) than the control group. DED was present in 28/70 patients in the study group and 6/35 patients in the control group (P = 0.018). More patients in the study group complained of dryness (P = 0.001), a gritty or sandy sensation (P < 0.001) and redness (P = 0.048). In the study group, the patients with DED were significantly different from the patients without DED in both TFBUT (P < 0.001) and corneal staining (P < 0.001). More patients in the DED group were likely to report dryness (P = 0.013) and watery or teary eyes (P = 0.012). The differences in meibomian gland obstruction scores between the study and the control group, the DED and the non-DED group were not significant (P = 0.105 and P = 0.077, respectively). The values for microcysts and bleb heights were significantly higher in the DED group (P = 0.040 and P = 0.011, respectively). A Spearman’s rank correlation showed that microcysts were positively correlated with corneal staining (r = 0.270, P = 0.024). Bleb height was negatively correlated with TFBUT (r = -0.299, P = 0.012) and positively correlated with corneal staining (r = 0.275, P = 0.021). The relationships between DED and microcysts and between DED and bleb height were significant (r = 0.247, P = 0.039 and r = 0.307, P = 0.010, respectively).ConclusionDED is relatively common in patients with functioning filtering blebs following trabeculectomy. In DED patients, dryness and watery are common symptoms. Microcysts and bleb height are related to ocular surface instability and DED.

The ocular surface after successful glaucoma filtration surgery: a clinical, in vivo confocal microscopy, and immune-cytology study

“…This seems in accordance with our study, that considered early to moderate glaucoma. In a different study, Ji and coworkers reported that 40% of patients with functioning filtering blebs suffered from symptomatic dry eye, with higher CFS scores and lower BUT values 16 . Interestingly, the occurrence of dry eye significantly correlated with the bleb features, being higher in patients with elevated and microcystic blebs.…”

“…Nevertheless, as stated above, other factors must be considered when interpreting the post-surgical OS system changes. (i) The mechanical effects of the new-formed filtration bleb may disturb the tear film stability, and induce a persistency of a significant form of dry eye 16,17,27,28 . (ii) The use of intra-operative MMC induces toxic effects on the OS system, by inhibiting the proliferation of corneal and conjunctival cells, and disturbing MGs 18,29 .…”

“…This may lead to a worsening of all tear film components after surgery, thus limiting in part the final improvement of the OS. Nevertheless, the effects of MMC have been demonstrated to completely disappear six months after surgery, with goblet and epithelial cells recovering their normal density 30,31 . (iii) The use of post-operative steroids may have had a huge effect on the final OS modifications, because of the inflammation decrease and the inhibitory effects on the recruitment of sub-conjunctival fibroblasts in the inflammatory phase of the bleb formation.…”

“…When filtration surgery is completely successful it may potentially produce significant improvements of the OS system through different mechanisms. Consequently, the positive change of the OS status may produce potential benefits for the patient QoL; however, on the other hand, the presence of a filtering bleb may induce different OS alterations and maintain, at least in part, a mitigated form of OSD 16–18 . These aspects may probably account for the worse QoL experienced by surgically compared to medically treated glaucomatous patients 19 .…”

Subconjunctival PRGF Fibrin Membrane as an Adjuvant to Nonpenetrating Deep Sclerectomy: A 2-Year Pilot Study

“…First, the lack of a standardized test orientated to evaluate filtering bleb dysesthesia. Second, there was a high prevalence of dry eye among the glaucoma-operated patients even with functioning blebs [45] . Our study shows low values on the OSDI scale.…”