Ophthalmology Q&A

Ophthalmology Q&A Which bones make up the orbit? - ANSWER->>1) Frontal 2) Zygomatic 3) Greater + Lesser Wing of Sphenoid 4) Maxilla 5) Lacrimal 6) Ethmoid 7) Palatine What is the cornea? - ANSWER->>Clear structure that vaults over pupil/iris 0.5 mm thick in center Type I collagen fibers arranged REGULARLY, DEHYDRATED Avascular What is the sclera? - ANSWER->>White, opaque wall of the eye. Continuous with cornea Type I collagen fibers arranged more IRREGULARLY, HYDRATED What is the anterior chamber? - ANSWER->>Space between cornea and iris/pupil Filled with aqueous fluid (produced in ciliary body, located posterior to iris) What is the iris? - ANSWER->>Pigmented, thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. Contains sphincter and dilator muscles. What are the canthi? - ANSWER->>Either corner of the eye where the upper and lower eyelids meet. More specifically, the inner and outer canthi are, respectively, the medial and lateral ends/angles of the palpebral fissure. What is the caruncle? - ANSWER->>It is the small, pink, globular nodule at the inner corner (the medial canthus) of the eye. It is made of skin covering sebaceous and sweat glands. What is the orbital septum? - ANSWER->>A membranous sheet that acts as the anterior boundary of the orbit. It extends from the orbital rims to the eyelids. It forms the fibrous portion of the eyelids. Location of orbital septum - ANSWER->> What is orbital fat? - ANSWER->>Orbital fat lies posterior to the orbital septum and anterior to the levator aponeurosis (upper lid) or the capsulopalpebral fascia (lower lid). Orbital fat - ANSWER->> What is the ciliary body? - ANSWER->>The ciliary body is a circular band of muscle that is connected to and sits immediately behind the iris What does the ciliary body do? - ANSWER->>1. Controls lens shape by pulling or relaxing on the lens zonules. 2. Produces aqueous humor which fills the posterior and anterior chambers and provides nutrition for avascular tissues in the eye such as the cornea. What is the lens? - ANSWER->>Proteinaceous structure located just posterior to pupil. Held in place by zonular fibers (attached to ciliary body) What is the vitreous body? - ANSWER->>The vitreous body/humour is the clear gel that fills the space between the lens and the retina of the eyeball. It keeps the center of the eye clear so that light can get to the retina and vision can begin. The gel and its fluid allow oxygen and nutrients to flow from the front of the eye to the back of the eye. In youth, the vitreous body is a shock absorber during eye movement, head movement, and physical exertions of the body. It is also rich in anti-oxidants that protect the various parts of the eye. What is the retina? - ANSWER->>A layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed. What is the optic nerve? - ANSWER->>CNII - paired nerve that transmits visual information from the retina to the brain. Contains axons of ganglion cells in retina. Extends intracranially from optic disc --> optic nerves--> optic chiasm --> optic tract --> lateral geniculate nucleus --> pretectal nuclei --> superior colliculus What is the conjunctiva? - ANSWER->>Clear, transparent membrane that lines the inner surfaces of the eyelids and and continues on to cover the front surface of the eyeball, except for the central clear portion of the outer eye (cornea). What are the three types of conjunctiva? - ANSWER->>1) bulbar conjunctiva 2) palpebral conjunctiva 3) fornix conjunctiva What is the bulbar conjunctiva? - ANSWER->>This portion of the conjunctiva covers the anterior part of the sclera. The bulbar conjunctiva stops at the junction between the sclera and cornea; it does not cover the cornea. (thin) Contains goblet cells which secrete mucin. What is the palpebral conjunctiva? - ANSWER->>This portion covers the inner surface of both the upper and lower eyelids. (thick) CONTINUES...