Netilmicin, an antibacterial aminoglycoside, is well tolerated even in an experimental wound-healing model where the integrity of the ocular surface is compromised, whereas ofloxacin, a fluoroquinolone, appears to provoke an inflammatory response in the normal eye and a clear alteration of reepithelialization in the wounded eye. These findings suggest that netilmicin may offer a superior toxicological profile in both normal eyes and clinical situations where the integrity of the ocular epithelium is suspect.

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Objective: The purpose of this study was to obtain a primary cell culture of bovine origin similar to the conjunctiva in terms of morphology and cell types, which could be of use for in vitro toxicity studies. Methods: After separation from the stroma by enzymatic treatment, conjunctival epithelial cells were dissociated and plated onto collagen-coated Transwell^® filters (1.13 cm² area). One group of plates was maintained in immersion and another was cultured under air-lifted conditions. Anti-epithelial keratin antibodies (AE1/AE3, K4) and antidesmoplakin 1 and 2 were used to characterize the cells by indirect immunofluorescence. The cell layer was examined after histological processing of the Transwell filter. Ultrastructural analysis was carried out by scanning electron microscopy (SEM). The bioelectric parameters transepithelial electrical resistance (TEER), potential difference (PD), short circuit current and paracellular permeability profile of carboxyfluorescein were monitored as indices of the functional characteristics of these cultures. Cytotoxicity was evaluated on morphological and functional (TEER) grounds after treating the cultures with several test substances. Results: Morphological studies showed pure and homogeneous cell cultures. In the SEM analysis, we observed contiguous polygonal cells with numerous short microvilli, a characteristic proportion of light, medium and dark cells and a sparse population of rounded PAS-positive cells, i.e. resembling goblet cells. Air-lifted cultures also showed a tissue-like cellular organization (8–9 layers). Immersion cultures reached a maximum TEER value of around 2.95 kΩ·cm² 7 days after plating while in air-lifted cultures TEER peaked up to 5.59 kΩ·cm² 11 days after plating. With regard to the use of bovine conjunctival epithelial cells (BCECs) for cytotoxicity screening, the system responded finely to the insults and yielded morphological and functional results in accordance with data obtained in vivo. Conclusions: BCECs reproduce cell morphology and differentiation of the original tissue and should prove a useful tool for initial studies of drug toxicity.

Netilmicin, at the concentrations used, is an antibiotic devoid of obvious cellular toxicity and may also be considered as a suitable first-choice drug in the treatment of those pathologies that compromise the integrity of the ocular surface.

Aim: The effects of the administration of three tear substitutes on normal conjunctival epithelium of the mouse, with particular regard to goblet cells, were studied. Methods: Three-month-old Swiss CD 1 mice were divided into four groups of 7 animals each. Group 1 was untreated (control). The other animals were treated with the instillation of 5 drops/day for 10 days as follows: group 2, 0.2% sodium hyaluronate (SH); group 3, 0.5% hydroxypropylmethylcellulose (HPMC); group 4, 0.9% NaCl. The entire conjunctiva was processed for light and electron microscopy. A morphometric study was performed to evaluate: the number and size of goblet cells and the number, size and optical density of mucin granules. Furthermore, Alcian blue/periodic acid-Schiff (AB/PAS) staining for goblet cells was carried out. Results: The SH-treated group showed that the area and number of goblet cells were similar to the untreated group; the mucin granules were reduced in number and optical density but increased in size. The HPMC-treated group showed a reduced area of goblet cells with reduced optical density of mucin granules. The saline-treated group showed that goblet cells were reduced in area and number; mucin granules showed a reduction in number and optical density and an increased size. The AB/PAS stain showed that each treatment was able to induce a treatment-specific modification of the staining characteristics of goblet cells. Conclusion: Our results strongly suggest that tear substitutes can induce treatment-specific modifications of the conjunctival epithelium with particular regard to goblet cell structure and ultrastructure.

Laser assisted refractive surgery is a common procedure for the correction of visual defects. However, this technique is sometimes associated with complications such as recurrent erosion scars or late-onset corneal haze formation due to irregular wound healing. In order to improve the risk/benefit ratio of this surgery, a better understanding of the wound healing process is absolutely necessary. The aim of the present study was to investigate in an animal model the influence of biopolymeric hydrogels in the modulation of the wound healing. Mechanical wounds were generated in rabbit cornea with the aid of an Algerbrush burr. The closure of the wound was monitored after staining with fluorescein by means of a confocal microscope. A hydrogel based on 1% xanthan gum stimulated significantly corneal wound healing whereas other viscosified solutions or hydrogels based on lower concentrations of xanthan gum or on hyaluronic acid did not promote wound healing.

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