In vivo Confocal Microscopy Study of Corneas in Healthy Subjects and POAG Patients in Topical Betablocker Therapy With and Without Preservatives

Abstract

Purpose: : To evaluate and compare with confocal microscopy the density and distribution of dendritic cells (DCs) in central and limbal cornea of healthy subjects and patients with primary open angle glaucoma (POAG) in topical betablocker therapy with and without preservatives.

Methods: : Controlled cross sectional study on 30 POAG patients (30 eyes) in topical betablocker therapy preserved with benzalkonium chloride (BAK) since no less than 6 months, mean age 61.3±15.8 years (group 1); 30 POAG patients (30 eyes) in topical betablocker therapy without BAK since no less than 6 months, mean age 66.06±14.14 years (group 2) and 30 healthy subjects (30 eyes), mean age 68.66±12.4 years (group 3). Complete ophthalmologic examination, SAP, in vivo scanning laser confocal microscopy of central and limbal cornea (HRT II Rostock cornea module, Heidelberg Engineering GmbH, Heidelberg, Germany) were performed. DCs density (cell/mm²) was calculated with image analysis software. Wilcoxon-Mann-Whitney test was used for statistics with random selection of one eye per subject.

Results: : DCs were observed in the basal epithelial layer, basal lamina and sub basal nerve plexus of central cornea and in the basal layer and basal membrane of limbal epithelium in the 3 groups. DCs density was significantly greater in both locations in group 1 (centre: 161.7±26.17 cell/ mm², limbus: 172.3±24.1 cell/mm²) than group 2 (centre: 43.1±12.54 cell/ mm², Z=6.609, p=0.000; limbus: 81.26±23.43 cell/mm², Z=6.617, p=0.000) and 3 (centre: 36.13±19.46 cell/ mm², Z=6.62, p=0.000; limbus: 81.2±25.2 cell/mm², Z=6.621, p=0.000). DCs density was greater, even if not significantly, at central cornea in group 2 than group 3 (Z=1.098, p=0.272), whereas there was no significant difference at limbus between the two groups (Z=0.168, p=0.867).

Conclusions: : In our study, DCs were found either in healthy corneas either in POAG patients corneas. DCs density was higher in POAG patients in betablocker therapy, particularly in group 1, suggesting a possible role of preservatives in mechanisms of irritative-inflammatory type causing a DCs increase.

Keywords: microscopy: confocal/tunneling • cornea: epithelium • imaging/image analysis: clinical