Eye Disorders, Part 1: Disorders of the Orbit, Lid, Conjunctiva & Sclera

Vocabulary practice flashcards covering clinical definitions, etiologies, examinations, visual presentations, and differentials of disorders affecting the orbit, eyelids, lacrimal apparatus, conjunctiva, and sclera.

Optometry

A health care profession practiced by a Doctor of Optometry (OD), requiring a bachelor's degree plus a 4-year graduate program, qualified to assess overall eye health, prescribe glasses/contacts, prescribe ocular medications, and perform select minor procedures.

Ophthalmology

A branch of medicine practiced by physicians (MD or DO) requiring 4 years of medical school, a 4-year surgical and medical residency, and optional 1–2 year fellowships in subspecialties like cornea, glaucoma, retina, and oculoplastics.

Nystagmus

An involuntary rhythmic oscillation or tremor of the eye defined by the direction of gaze in which it appears, the direction of fast and slow phases (or pendular oscillation), and the plane of movement (horizontal, vertical, rotary).

Pendular Nystagmus

A type of nystagmus characterized by coarse oscillations that lack distinct quick and slow phases.

Strabismus

Any form of ocular misalignment resulting from abnormalities in extraocular muscles, cranial nerve palsies, brainstem lesions, or orbital disease, which can lead to diplopia or amblyopia.

Tropia

A manifest strabismus that is present without interruption of the visual axis, diagnosed with the cover test where the examiner watches the uncovered eye for refixation movement.

Phoria

A latent strabismus that is only present when binocular fixation is interrupted, diagnosed with the cover-uncover test where the examiner watches the covered eye as the cover is removed.

Hirschberg Corneal Light Reflex Test

The initial objective screening test for strabismus performed by projecting a light source onto the cornea to evaluate the symmetry of the light reflection in both eyes.

Classifications of Strabismus Deviations

Specific directions of ocular deviation: esotropia (inward), exotropia (outward), hypertropia (upward), and hypotropia (downward).

Amblyopia

A functional visual reduction in one or both eyes resulting from abnormal visual experience and cortical underdevelopment during early childhood ('lazy eye').

Deprivation Amblyopia

A form of amblyopia caused by physical obstruction of the visual axis (such as ptosis, cataract, or therapeutic patching) that deprives the visual cortex of sensory stimulation.

Refractive Amblyopia (Anisometropia)

Amblyopia resulting from a significant difference in refractive error between both eyes, leading to cortical suppression of the blurred image from the affected eye.

Strabismic Amblyopia

Amblyopia resulting from ocular misalignment in which the brain actively suppresses the non-matching image coming from the deviating eye to avoid double vision.

Orbital Septum

A fibrous fascial sheet extending from the orbital margins into the eyelids that serves as an anatomical barrier separating superficial preseptal tissues from postseptal orbital contents.

Periorbital Cellulitis (Preseptal Cellulitis)

Infection of the eyelid and periocular tissue anterior to the orbital septum, presenting with ocular pain, erythema, and edema without pain on extraocular movement, proptosis, or ophthalmoplegia.

Orbital Cellulitis (Septal Cellulitis)

An emergency deep infection of the postseptal orbital tissue (fat and ocular muscles), characterized by fever, proptosis, ophthalmoplegia, and pain with eye movement.

Hordeolum (Stye)

An acute, localized, painful, and tender erythematous pustule near the eyelash line caused by staphylococcal inflammation of an eyelash follicle, gland of Zeis/Moll (external), or meibomian gland (internal).

Chalazion

A chronic, non-tender, firm, rubbery granulomatous nodule on the eyelid caused by obstruction of a meibomian gland.

Blepharitis

Chronic inflammation and scaling of the eyelid margins, categorised as anterior (skin, lashes, and follicles) or posterior (associated with meibomian gland dysfunction).

Entropion

Inversion or inward turning of the eyelid margin, frequently age-related (involutional), resulting in trichiasis, irritation, and potential corneal abrasion.

Ectropion

Eversion or outward folding of the eyelid margin (most commonly lower lid), causing epiphora, conjunctival exposure, and dry-eye symptoms.

Dacryoadenitis

Inflammation or infection of the lacrimal gland presenting as unilateral or bilateral swelling and erythema over the outer superolateral aspect of the upper eyelid.

Dacryocystitis

Infection and inflammation of the lacrimal sac presenting with erythema, warmth, swelling, and purulent discharge located below the medial canthus.

Dacryostenosis

Congenital or acquired narrowing or obstruction of the nasolacrimal duct leading to epiphora, tear pooling, and mucoid discharge.

Bacterial Conjunctivitis

A highly contagious conjunctival infection characterized by unilateral injection and thick, purulent discharge that persists throughout the day and commonly cements eyelids shut in the morning.

Gonococcal Conjunctivitis

A hyperacute, severe form of bacterial conjunctivitis that is an ophthalmologic emergency due to the risk of rapid corneal perforation, treated with ceftriaxone 1g IM.

Viral Conjunctivitis

A self-limited, highly contagious ocular infection primarily caused by Adenovirus, manifesting with watery discharge, a gritty foreign body sensation, preauricular lymphadenopathy, and a viral prodrome.

Allergic Conjunctivitis

A Type 1 IgE-mediated hypersensitivity reaction triggered by airborne allergens, manifesting with bilateral intense itching, chemosis, watery stringy discharge, and palpebral cobblestoning.

Chemical Conjunctivitis (Toxic Conjunctivitis)

Ocular surface damage and irritation caused by exposure to offending chemicals or preservatives in eye drops, often visible as punctate epithelial staining with fluorescein.

Keratoconjunctivitis Sicca

Dry eye syndrome resulting from deficient aqueous tear production (lacrimal gland dysfunction) or increased tear evaporation (meibomian gland lipid layer deficiency).

Subconjunctival Hemorrhage

A sharply demarcated accumulation of blood beneath the conjunctiva caused by ruptured conjunctival vessels following trauma, sneezing, coughing, or straining, which resolves spontaneously within 2 weeks.

Hyphema

A pooling or collection of gross blood inside the anterior chamber of the eye, most commonly caused by blunt ocular trauma.

Pinguecula

A benign, yellowish, raised elastotic conjunctival deposit caused by chronic exposure to UV radiation, wind, or dust that does not invade the cornea.

Pterygium

A triangular, fleshy, fibrovascular wedge of proliferating bulbar conjunctival tissue that extends past the limbus and encroaches onto the cornea.

Scleritis

A severe, sight-threatening transmural inflammation of the sclera frequently linked to rheumatoid arthritis, presenting with deep, boring pain radiating to the face and a violaceous scleral hue.

Episcleritis

A benign, self-limited inflammation of the vascular episcleral tissue characterized by sectoral, bright red or pink injection that blanches upon instillation of topical phenylephrine.