RESUMO
Achiasmia is a rare visual pathway maldevelopment with reduced decussation of the axons in the optic chiasm. Our aim was to investigate clinical characteristics, macular, optic nerve and brain morphology in achiasmia. A prospective, cross-sectional, observational study of 12 participants with achiasmia [8 males and 4 females; 29.6 ± 18.4 years (mean ± standard deviation)] and 24 gender-, age-, ethnicity- and refraction-matched healthy controls was done. Full ophthalmology assessment, eye movement recording, a high-resolution spectral-domain optical coherence tomography of the macular and optic disc, five-channel visual-evoked responses, eye movement recordings and MRI scans of the brain and orbits were acquired. Achiasmia was confirmed in all 12 clinical participants by visual-evoked responses. Visual acuity in this group was 0.63 ± 0.19 and 0.53 ± 0.19 for the right and left eyes, respectively; most participants had mild refractive errors. All participants with achiasmia had see-saw nystagmus and no measurable stereo vision. Strabismus and abnormal head position were noted in 58% of participants. Optical coherence tomography showed optic nerve hypoplasia with associated foveal hypoplasia in four participants. In the remaining achiasmia participants, macular changes with significantly thinner paracentral inner segment (P = 0.002), wider pit (P = 0.04) and visual flattening of the ellipsoid line were found. MRI demonstrated chiasmatic aplasia in 3/12 (25%), chiasmatic hypoplasia in 7/12 (58%) and a subjectively normal chiasm in 2/12 (17%). Septo-optic dysplasia and severe bilateral optic nerve hypoplasia were found in three patients with chiasmic aplasia/hypoplasia on MRI. In this largest series of achiasmia patients to date, we found for the first time that neuronal abnormalities occur already at the retinal level. Foveal changes, optic nerve hypoplasia and the midline brain anomaly suggest that these abnormalities could be part of the same spectrum, with different manifestations of events during foetal development occurring with varying severity.
RESUMO
Recently, hydrogels based on natural water-soluble polysaccharides have attracted more and more attention due to their favorable characteristics. The high water-holding capacity, lack of toxicity, and biodegradability of such hydrogels make it possible to develop new materials on their basis for biotechnological, biomedical, pharmacological, and medical purposes. Sodium alginate is a non-toxic natural polysaccharide found in marine algae. It is capable of forming solid gels under the action of polyvalent cations that cross-link polysaccharide chains. Alginate-based products are popular in many industries, including food processing, pharmaceutical, and biomedical applications. Cellulose is the most abundant, renewable, and natural polymer on Earth, and it is used for various industrial and biomedical applications. Carboxymethyl cellulose (CMC) is useful in pharmaceutical, food, and non-food industries such as tablets, ice cream, drinks, toothpaste, and detergents. In this review, various methods for the preparation of the compositions based on sodium alginate and CMC using different crosslinking agents have been collected for the first time. Additionally, the drug release profile from such polymer matrixes was analyzed.