ABSTRACT
AIMS: To analyse myelination and outgrowth of the optic axons in relation to the neuro-ophthalmological manifestations of ethanol (EtOH) abuse during pregnancy. METHODS: An experimental model of chronic EtOH exposure was developed in rats and their offspring by subjecting the dams to a liquid diet (35% of the daily total calories as either EtOH or maltose-dextrose nutritional controls (Con). Eyeballs and optic nerves were obtained at key developmental stages and processed for morphologic, immunocytochemical and immunoblotting procedures, using alternatively antibodies against myelin basic protein (MBP) or neurofilament (NF) protein, and image analysing. RESULTS: A significant delay in onset of optic axons myelination, as well as a significant reduction in optic nerve size (P < 0.001), optic axons number (P < 0.001), myelinated axons density (P < 0.001), number of myelin lamellae linked to axon diameter (P < 0.001) and optic axon cross-sectional area (P < 0.001) were detected in the global morphometric assessment of the EtOH nerves with respect to the Con. Expression of MBP and NF was noticeably reduced in the EtOH optic nerves when compared with the Con. CONCLUSION: Disturbed myelination of optic axons, caused by EtOH abuse, strongly disrupts the optic nerve development and the establishment of definitive retinal and optic nerve targets, and subsequently the visual patterns.
Subject(s)
Central Nervous System Depressants/toxicity , Ethanol/toxicity , Eye/physiopathology , Myelin Basic Protein/biosynthesis , Myelin Sheath/pathology , Neurofilament Proteins/biosynthesis , Optic Nerve/pathology , Prenatal Exposure Delayed Effects , Animals , Animals, Newborn/physiology , Axons/drug effects , Axons/pathology , Axons/physiology , Body Weight , Central Nervous System Depressants/blood , Disease Models, Animal , Ethanol/blood , Eye/drug effects , Eye/growth & development , Eye/metabolism , Female , Myelin Basic Protein/immunology , Myelin Sheath/drug effects , Myelin Sheath/physiology , Neurofilament Proteins/immunology , Optic Nerve/growth & development , Optic Nerve/physiology , Pregnancy , Rats , Rats, Wistar , Retina/anatomy & histology , Retina/pathology , Time FactorsABSTRACT
The early development of lens opacities and lens subluxation are the most common causes of vision loss in patients with anterior megalophthalmos (AM). Cataract surgery in such patients is challenging, however, because of anatomical abnormalities. Intraocular lens dislocation is the most common postoperative complication. Patients with AM also seem to be affected by a type of vitreoretinopathy that predisposes them to retinal detachment. We here present the case of a 36-year-old man with bilateral AM misdiagnosed as simple megalocornea. He had a history of amaurosis in the right eye due to retinal detachment. He presented with vision loss in the left eye due to lens subluxation. Following the removal of the subluxated lens, it was deemed necessary to perform a vitrectomy in order to prevent retinal detachment. Seven months after surgery, an Artisan® Aphakia iris-claw lens was implanted in the anterior chamber. Fifteen months of follow-up data are provided.
ABSTRACT
Clinical and experimental studies have highlighted the role played by thyroid hormones (TH) in neural and neuro-sensorial development. However, knowledge on TH mechanisms on the developing visual system is still incomplete. To uncover TH actions on the eyes and vision we carried out a microscopical study on the role of TH in the developing retina and optic nerve, in a rat model of controlled TH deficiency (THD). Morphometric and stereological analyses of the retina and optic nerve showed a reduction in the volume of the eye (p<0.001) and optic nerve cross-sectional area (p<0.001), and thinning of the retinal layers (p<0.001). Glial development and myelination was significantly delayed in the THD optic nerves (p<0.001), as compared to controls. The data indicate that TH play an essential role in neuro-retinogenesis. Substitutive TH therapy in critical periods, should be considered in hypothyroidism-related eye disorders as well as neurodegenerative retinal processes.