Protein Drug Delivery Using a Novel Maxillofacial Technique Targeting the Visual Pathway in the Brain, the Optic Nerve, and the Retina.

Protein drugs are used for treating many diseases of the eye and the brain. The formidable blood neural barriers prevent the delivery of these drugs into the eye and the brain. Hence, there is a need for a protein drug delivery system to deliver large proteins across blood-neural barriers. Low half-life, poor penetration of epithelial barriers, low stability, and immunogenicity limit the use of non-invasive systemic routes for delivering proteins. In this pre-clinical study, the efficacy of a new maxillofacial route for administering protein drugs using a novel drug delivery system is compared with systemic administration through intra-peritoneal injection and ocular administration through topical eye drops and subconjunctival and intravitreal injections. Bevacizumab and retinoschisin proteins were administered using the maxillofacial technique along with systemic and ocular routes in wild-type male C57BL/6J mice. Liquid chromatography with tandem mass spectrometry and western blot was used to detect bevacizumab in tissue samples. Furthermore, immunohistochemistry was performed to detect the presence and localization of bevacizumab and retinoschisin in the retina and brain. The maxillofacial route of delivery could target the brain including regions involved in the visual pathway and optic nerve. The maxillofacial technique and intravitreal injection were effective in delivering the drugs into the retina. A new concept based on the glymphatic pathway, cerebrospinal fluid drug distribution, and the crossover of ipsilateral optic nerve fibers at optic chiasma is proposed to explain the presence of the drug in contralateral eye following maxillofacial administration and intravitreal injection.

Acute bilateral retrobulbar optic neuritis - An atypical sequela of COVID-19.

Coronavirus disease 19 (COVID-19) and its ophthalmic manifestations have been variably portrayed. We report a case of a 56-year-old female presenting with sudden-onset vision loss associated with painful extraocular muscle movements in both eyes following COVID-19. Visual acuity was counting fingers close to face. Color perception tested was inaccurate. Ocular examination revealed sluggishly reacting pupils and an otherwise unremarkable fundus picture in both eyes, giving us an impression of bilateral retrobulbar neuritis. Magnetic resonance imaging of the brain and orbit were unremarkable, while blood investigations revealed nothing suggestive. The patient dramatically improved with steroid therapy with full visual recovery and a color vision defect. This presentation of bilateral retrobulbar neuritis as a sequela of COVID-19 is presented for its rarity.

Foveal and Macular Thickness Evaluation by Spectral OCT SLO and Its Relation with Axial Length in Various Degree of Myopia.

PURPOSE: To evaluate the foveal and macular thickness in various degrees of myopia and its association with axial length in low, moderate and high degrees of myopia. DESIGN: A cross-sectional study was done in the Department of Ophthalmology, MGMCRI, Pondicherry, India. MATERIALS AND METHODS: One hundred and twenty five eyes eyes of 64 myopic subjects between the age group of 20-40 who fulfilled the inclusion criteria were selected and complete ophthalmic examination was done. Cycloplegic refraction was done and the subjects were categorized into low (n=43 eyes), moderate (n=43 eyes) and high (n=36) degrees of myopia. The foveal and macular thickness was assessed using spectral OCT- SLO and axial length was measured by A-scan biometry. RESULTS: The foveae minimum of high myopia (178 ± 26.4 microns) was significantly thicker compared to moderate myopia (p= 0.028). There was no significant intergroup difference in the thickness significance of the outer and inner macular between mild, moderate and high degree of myopia. The mean axial length of high myopia (26.7±0.97mm) was significantly higher compared to moderate (24.6±0.81mm) and low myopia (23.5±0.81mm) with a p-value of p = 0.001. There was a positive correlation of axial length with foveae minimum, fovea and superior inner macula in respect to myopia (p<0.05). CONCLUSION: The foveal and macular thickness in myopia is influenced by the axial length. Early detection of such changes in macular thickness by using OCT is helpful in understanding the mechanism and factors affecting the structural changes of myopic eyes. Also it implicates the importance of refractive error induced retinal macular changes while interpreting OCT.