An ophthalmically acceptable vehicle, comprising: an aqueous suspension having a first viscosity, said suspension comprising between 0.1% and 6.5% by weight, based on the total weight of the suspension, of a carboxyl-containing polymer prepared by polymerization of one or more monoethylenically unsaturated monomers containing carboxyl and less than 5% by weight of a cross-linking agent, said percentages of monomers being referred to the total weight of the polymerized monomers, said carboxyl-containing polymer having an average particle size not more than 50 μm of equivalent spherical diameter, in which the carboxyl-containing polymer is polycarbophil, and a sufficient amount of a second polymer that allows said carboxyl-containing polymer to remain in suspension, in which after coming into contact with the tear fluid, said vehicle gels to a second viscosity that is greater than l at first viscosity, in which the second polymer is a cationic polymer, in which the cationic polymer is chitosan, and in which the chitosan has a molecular weight between 50 kDa (50,000 g / mol) and 100 kDa (100,000 g / mol) and is present in a range between 0.01% and 5.0% by weight, or in which the chitosan has a molecular weight between 1000 kDa (1000,000 g / mol) and 3,000 kDa (3,000 .000 g / mol) and is present in a range between 0.01% and 0.05% by weight.Un vehículo oftálmicamente aceptable, que comprende: una suspensión acuosa que tiene una primera viscosidad, comprendiendo dicha suspensión entre 0,1 % y 6,5 % en peso, respecto al peso total de la suspensión, de un polímero que contiene carboxilo preparado mediante polimerización de uno o más monómeros monoetilénicamente no saturados que contienen carboxilo y menos del 5 % en peso de un agente de enlace cruzado, estando dichos porcentajes de monómeros referidos al peso total de los monómeros polimerizados, teniendo dicho polímero que contiene carboxilo un tamaño de partícula medio no mayor de 50 μm de diámetro esférico equivalente, e
