Basics of Ophthalmology for Dental Students

Cornea = Transparent and avascular, admits light into the eye Sclera = White opaque tough coat of the eyeball, pierced by the optic nerve Iris = Forms the colored part of the eye, has a central opening called the pupil Retina = Inner receptive coat of the eyeball

Cornea and Sclera = Outer protective coat of the eyeball Iris = Controls the amount of light entering the eye Ciliary Body = Attached to the root of the iris, involved in accommodation for near vision Choroid = Vascular and pigmented layer, provides nutrition to the eye

Cornea = 11 mm in diameter, 0.5 mm in thickness Sclera = 1 mm in thickness Eyeball = About 24 mm in diameter Optic Nerve = Pierces posterior part of sclera

<p>Sphincter pupillae = Controls the size of the pupil Ciliary body = Secretes aqueous humor and responsible for accommodation Choroid = Highly vascular and responsible for nutrition of adjacent structures Retina = Converts light rays into electric impulses and contains light receptors</p> Signup and view all the answers

<p>Ciliary body = Between the iris and the choroid Choroid = Extends backwards from the ciliary body and highly pigmented Retina = Inner layer of the eyeball containing 3 layers of cells Macula lutea = Most posterior part, rich in cones, and responsible for acute sharp vision</p> Signup and view all the answers

<p>Eyelids and conjunctiva = Act as a curtain to protect the front surface of the globe and are connected to the eyeball by a mucus membrane Lacrimal apparatus = Consists of secretory part in the upper outer part of the orbit and excretory part consisting of puncta, canaliculi, sac, and duct Bony orbit = Contains orbital cavities with 4 walls and various contents such as eyeball, extraocular muscles, nerves, vessels, fat, and fascia Lid muscles = Include orbicularis oculi and levator palpebrae superioris, supplied by specific nerves, and have specific arterial, venous, and lymphatic drainage</p> Signup and view all the answers

<p>Superior rectus = Oculomotor nerve Inferior rectus = Oculomotor nerve Medial rectus = Oculomotor nerve Superior oblique = Trochlear nerve</p> Signup and view all the answers

<p>Superior orbital fissure = Separates the roof from the lateral wall Inferior orbital fissure = Separates the floor from the lateral wall</p> Signup and view all the answers

<p>Slit lamp biomicroscopy = Used for detailed ocular examination till the level of the crystalline lens Retinoscope = Used for optical examination of errors of refraction Direct ophthalmoscope = Used for fundus examination Applanation tonometer = Used for measurement of intraocular pressure (IOP)</p> Signup and view all the answers

<p>Orbital cellulitis = Proptosis, inflammation, fever, rigors Phlyctenular kerato-conjunctivitis = Photophobia, lacrimation, pricking pain, small yellowish nodule</p> Signup and view all the answers

<p>Iridocyclitis = Symptoms of pain, photophobia, headache and blurring of vision Optic neuritis = Rapid diminution of vision, with pain with ocular movements Glaucoma = Acute rise in IOP within 1-2 hours, accompanied by severe ocular pain, headache, vomiting, fever and malaise Cataract = Presented with haloes and glare around light, difficulty in night vision, followed by gradual diminution of vision</p> Signup and view all the answers

<p>Iridocyclitis = Local corticosteroid eye drops and ointment Optic neuritis = Systemic steroids may be needed in some cases Glaucoma = Intravenous mannitol to reduce aqueous secretion Cataract = Cataract extraction operation by phacoemulsification</p> Signup and view all the answers

<p>Primary glaucoma = Where there is no primary cause found Congenital glaucoma = May present since birth with large opaque cornea Acute primary glaucoma = Elderly patients (over 60 years) with acute rise in IOP within 1-2 hours Chronic primary glaucoma = Gradual onset over months and years with gradual limitation of vision</p> Signup and view all the answers

<p>Retinal detachment = First complaint may be flashes of light with increase in floaters Proptosis (exophthalmos) = Protrusion of the eyeball forward, may be unilateral or bilateral Squint (strabismus) = Condition where the two visual axes are not parallel to each other in any direction of gaze Orbital fractures = Caused by road traffic accidents, sports injuries or civil violence</p> Signup and view all the answers

<p>Comitant squint = Where there is no paralysis or restriction in any extraocular muscle and the angle of squint is constant in any direction of gaze Incomitant squint = Due to paralysis or restriction of one or more extraocular muscles Optic neuritis - Papillitis = Inflammation of the optic nerve head characterized by edema of the optic disc, engorgement of retinal vessels and hemorrhages Optic neuritis - Retrobulbar neuritis = Inflammation of the optic nerve behind the eyeball characterized by rapid diminution of vision, with pain with ocular movements</p> Signup and view all the answers

<p>Septic focus in the teeth or oral region = Lowers the resistance of the eye to infections due to disruption of the blood ocular barrier by operative trauma Blunt or penetrating trauma = Common predisposing factor for retinal detachment leading to separation of the neurosensory retina from the underlying choroid Operative trauma = Disruption of the blood ocular barrier leading to lowered resistance of the eye to infections after intraocular surgeries Old age = Cause for development of senile cataract due to opacity in the crystalline lens</p> Signup and view all the answers

<p>Congenital cataract = Due to prenatal infection (rubella or toxoplasma) Complicated cataract = Due to iridocyclitis or diabetes Traumatic cataract = Due to blunt or penetrating trauma Senile cataract = Due to old age and development of opacity in the crystalline lens</p> Signup and view all the answers

<p>Blow out fracture = Fracture of the orbital floor accompanied by herniation of orbital contents into the maxillary sinus and enophthalmus Medial wall fracture = Due to ethmoidal bone fractures accompanied by lacrimal sac injuries Lateral wall fracture = Caused by zygomatic bone fracture and displacement Upper wall fractures = Result from fracture of the frontal bone and may be accompanied by meningeal injury</p> Signup and view all the answers

<p>Emmotropia (Emmetropia) = Condition where parallel rays entering the eye are focused on the retina at rest (with no accommodation) Myopia (near-sightedness) = Parallel rays focus in front of the retina, near objects are seen clearly, whereas distant objects are indistinct Hyperopia (far-sightedness) = Parallel rays focus behind the retina, far objects are seen more clearly, whereas near objects are indistinct</p> Signup and view all the answers