Ophthalmology and Optometry
Ocular trauma is one of the most under-recognized causes of vision loss in the developed world. Blunt or penetrating ocular trauma can lead to vision loss through cataract or glaucoma. Etiologies of ocular injury differ in urban areas compared to other settings, and differ from country to country, between different regions of the world, and between differing demographic or socioeconomic classes.
Human eye works like a digital camera.
Light is focused primarily by the cornea — the clear front surface of the eye, which acts like a camera lens.
The iris of the eye functions like the diaphragm of a camera, controlling the amount of light reaching the back of the eye by automatically adjusting the size of the pupil (aperture).
In spite of being a small organ, the eyelids contain numerous histological elements that can be the origin of benign and malignant lesions.
The eyelids are composed of four layers: Skin and subcutaneous tissue, striated muscle (orbicularis oculi), tarsus, and conjunctiva.
Orbital tumors can be benign or malignant and arise primarily within the orbit or secondarily from an adjacent source, such as the eyelid, paranasal sinus, or intracranial compartment. Orbital tumors can also be metastatic from distant sites.
Some types of orbital tumors usually cause proptosis and displacement of the globe in a direction opposite the tumor. Pain, diplopia, and vision loss may also be present. The diagnosis of orbital tumors is suspected based on the history, examination, and neuroimaging (CT, MRI, or both), but confirmation often ultimately requires a biopsy. Causes and treatment vary by age group.
Most frequent uveal tumors are “ocular melanoma,” “uveal melanoma,” or “choroidal melanoma” are often used interchangeably. The terms describe melanomas, which arise from the eye, and can occur in the iris, ciliary body and/or choroidal regions of the eye. Melanomas are cancers that arise from specific types of pigmented (colored) cells in the body. Melanomas of the eye are rare.
The wall of the eye has 3 main layers. From outside to inside there is: the white sclera, a blood vessel layer called the uvea (choroid, ciliary body and iris) and an inner retinal layer. Further, the pigment producing cells, “melanocytes” are primarily found in the vascular uveal layer. It is those melanocytes that can turn into malignant melanoma. Therefore, when melanoma happens in the choroid, they are called “choroidal melanoma,” the most common primary intraocular malignancy in adults. That said, choroidal melanomas are rare with 5 to10 out of each million people diagnosed with a choroidal melanoma each year. Choroidal melanomas can spread to other parts of the body.
Conjunctival melanocytic lesions are the most common tumors of the conjunctiva, comprising 52% of all conjunctival tumors. Several classifications have been suggested for conjunctival melanocytic lesions. Thus far, the 1980 World Health Organization (WHO) classification has been most widely used and includes three pathologic categories: conjunctival nevus, conjunctival melanosis, and malignant melanoma (MM).
Lecture for General Medicine and Stomatology students
Neuro-ophthalmology is an academically-oriented subspecialty that merges the fields of neurology and ophthalmology, often dealing with complex systemic diseases that have manifestations in the visual system.
This work consists of basic information about pediatric ophthalmology.
Femtosecond laser uses an infrared beam of light to precisely separate tissue through a process called photodisruption by generating pulses as short as one-quadrillionth of a second. It has wavelength of 1053 nm and is based on the technology whereby focused laser pulses divide material at the molecular level without transfer of heat or impact to the surrounding tissue.