Developmental changes in accommodation evidenced by an ultrabiomicroscopy procedure in patients of different ages.

We demonstrate that changes in the behaviour of the contractile ciliary muscle accompanied by augmented rigidity of the lens are the most important aspects in the loss of accommodation. With ultrabiomicroscopy (UBM), we demonstrated that the performance of the ciliary muscle is diminished and accompanied by rigidity of the lens. Both lens thickness and trabecular-ciliary process distance (TCPD) were the parameters that showed major alterations with the loss of accommodation in patients of different ages.

Presbyopia: a new potential pharmacological treatment.

Presbyopia occurs after 40 years of age in humans with a progressive loss of accommodation. Accommodation depends on the contraction of the ciliary muscle and iris, lens changes and convergence. The parasympathetic system regulates the degree of ciliary muscle and iris contraction necessary to modify the shape and position of the lens and its stimulation is effective through the activation of muscarinic receptors that are present in both structures.

Visual defects associated with vigabatrin: a study of epileptic argentine patients.

Objective: The aim of the present study was to assess visual alterations in a population of Argentine patients treated with the antiepileptic drug vigabatrin.

Methods: Twenty patients receiving vigabatrin and 15 patients receiving carbamazepine were examined with automated perimetry using a Humphrey 120-point full screening strategy. In addition, scotopic flash electroretinograms were performed.

A new experimental model of glaucoma in rats through intracameral injections of hyaluronic acid.

An experimental model of pressure-induced optic nerve damage would greatly facilitate the understanding of the cellular events leading to ganglion cell death, and how they are influenced by intraocular pressure and other risk factors associated to glaucoma. The aim of the present report was to study the effect of a long-term increase of intraocular pressure in rats induced by intracameral injections of hyaluronic acid with respect to electroretinographic activity and retinal and optic nerve histology. For this purpose, hyaluronic acid was injected weekly in the rat anterior chamber of one eye, whereas the contralateral eye was injected with saline solution.

Effect of hyaluronic acid on intraocular pressure in rats.

Purpose: To study the effect of acute or chronic intracameral injection of hyaluronic acid on intraocular pressure (IOP) in rats.

Methods: Acute or chronic injections of hyaluronic acid were performed unilaterally in the rat eye's anterior chamber, whereas the contralateral eye was injected with saline solution. IOP was assessed daily or weekly by a tonometer in conscious rats.