CH 22 Visual problems

Comprehensive vocabulary flashcards covering the visual system, ocular assessment techniques, refractive errors, ophthalmic emergencies, intraocular pathologies, and postoperative nursing care.

Orbit

The bony eye socket that houses the eyeball, measuring on average $35\,\text{mm}$ high and $40\,\text{mm}$ wide, formed by 7 bones: frontal, zygoma, maxilla, ethmoid, sphenoid, lacrimal, and palatine.

Extraocular Muscles

The 6 voluntary striated muscles that originate from the apex of the orbit and insert on the sclera to coordinate binocular eye movement: the superior, inferior, medial, and lateral recti, along with the superior and inferior obliques.

Levator Palpebrae Superioris

The skeletal muscle located in the upper eyelid innervated by the superior division of cranial nerve III (CN III) that elevates and retracts the upper eyelid.

Lacrimal Apparatus

The physiological structure responsible for tear production and drainage, consisting of the main lacrimal gland, accessory lacrimal glands (glands of Wolfring and Krause), puncta, canaliculi, lacrimal sac, and nasolacrimal duct.

Eyeball (Globe) Layers

The 3 concentric tunics of the eye: the tough fibrous outer tunic (cornea, conjunctiva, and sclera), the vascular middle uveal tract (iris, ciliary body, and choroid), and the innermost neurosensory tunic (retina).

Cornea

The transparent, avascular anterior surface of the eye comprising 6 layers (epithelium, Bowman layer, stroma, Descemet membrane, Dua layer, and endothelium) that refracts incoming light rays onto the retina.

Sclera

The opaque, fibrous connective tissue forming the protective white outer coat of the eye, extending from the corneal limbus anteriorly to the sheath of the optic nerve posteriorly.

Aqueous Humor

A clear, watery fluid produced by the ciliary processes that fills the anterior and posterior chambers, nourishes avascular structures like the lens and cornea, and exits through the trabecular meshwork and canal of Schlemm.

Normal Intraocular Pressure (IOP)

The normal pressure range maintained within the eye by the balanced production and outflow of aqueous humor, which measures $10\text{ to }21\,\text{mm\,Hg}$.

Lens

A transparent, flexible biconvex structure situated directly behind the pupil and iris, suspended by zonular fibers (suspensory ligament), that changes shape to alter the focal distance of the eye.

Accommodation

The physiological mechanism by which the ciliary muscle contracts, reducing zonular tension and allowing the lens to become more convex to focus sharply on near objects.

Vitreous Humor

A transparent, inert gel-like substance that fills the posterior cavity located between the crystalline lens and the retina, transmitting light and maintaining retinal apposition.

Macula and Fovea Centralis

Specialized central retinal structures responsible for detailed central vision; the macula measures approximately $6\,\text{mm}$ in diameter, and its central avascular pit, the fovea, contains the highest concentration of cones for sharpest visual acuity.

Photoreceptors (Rods and Cones)

Retinal sensory neuroepithelial cells where rods (predominantly peripheral) mediate night and peripheral vision in monochrome, while cones (concentrated in the fovea) mediate sharp central vision and trichromatic color vision (red, green, blue).

Optic Disc

The creamy yellow, circular retinal landmark with distinct margins where retinal ganglion cell axons converge to form the optic nerve (CN II), creating an anatomic blind spot due to an absence of photoreceptors.

Visual Pathway

The anatomical route of visual transmission from the retina through the optic nerve to the optic chiasm (where nasal fibers decussate), lateral geniculate body, and optic radiations to the visual cortex in the occipital lobe.

Arcus Senilis

An age-related, benign physical finding characterized by a milky white-gray opaque ring encircling the corneal periphery due to stromal cholesterol and lipid deposition.

Snellen Eye Chart

A standardized visual acuity test positioned at a calibrated distance of $20\,\text{feet}\,(6\,\text{m})$ where the patient reads lines of decreasing letter sizes; recorded as a fraction where $20/20$ indicates normal distance vision.

Jaeger Chart

A handheld visual screener held at $14\,\text{inches}\,(35\,\text{cm})$ with graded paragraphs of varying print sizes used to evaluate near visual acuity in patients age 40 or older or those reporting near-reading difficulties.

Tonometry

The diagnostic measurement of intraocular pressure (IOP) performed by lightly applanating an anesthetized corneal surface with a probe to determine mean ocular tension.

PERRLA

An objective assessment finding indicating that the pupils are equal in size, round in shape, reactive to light (both directly and consensually), and reactive to accommodation (pupillary constriction and ocular convergence when shifting from distant to near focus).

Stereopsis

Three-dimensional binocular vision and depth perception allowing individuals to accurately judge distance and elevation, which is compromised when monocular vision occurs (e.g., patching, enucleation).

Refractometry

A subjective diagnostic examination measuring refractive error in which a patient looks through trial lenses at a Snellen chart to choose the lenses that produce the sharpest visual acuity.

Myopia

Nearsightedness; a refractive condition where parallel light rays focus in front of the retina because of excessive corneal/lenticular curvature or an abnormally long eyeball, causing distant objects to appear blurred.

Hyperopia

Farsightedness; a refractive error where light rays converge behind the retina because the eyeball is too short or refractive power is inadequate, requiring accommodation to visualize near objects clearly.

Presbyopia

The progressive, age-related loss of accommodation manifesting in the early to mid-40s as the crystalline lens becomes denser, larger, and less elastic, impairing near focusing.

Astigmatism

A refractive defect caused by an uneven, asymmetric curvature of the cornea or lens, resulting in unequal refraction along different meridians so light rays fail to focus to a single point on the retina.

Aphakia

The absence of the crystalline lens of the eye, which may occur congenitally, secondary to ocular trauma, or after surgical cataract extraction prior to intraocular lens (IOL) implantation.

LASIK (Laser-Assisted In Situ Keratomileusis)

A refractive surgical procedure where a microkeratome or laser creates a partial-thickness corneal flap that is folded back, allowing an excimer laser to vaporize and sculpt stromal tissue before replacing the flap without sutures.

Phakic Intraocular Lens (Phakic IOL)

An implantable artificial contact lens placed into the anterior or posterior chamber without removing the eye's natural crystalline lens, preserving natural accommodation for near vision in patients with severe myopia or hyperopia.

Legal Blindness

A diagnostic classification defined as a best-corrected visual acuity of $20/200$ or worse in the better eye, or a peripheral visual field restriction of $20^\circ$ or less.

Sighted-Guide Technique

A nursing ambulation method where the clinician walks slightly ahead and to one side of the visually impaired individual, allowing the patient to grasp the clinician's elbow while the nurse provides verbal orientation of upcoming terrain changes.

Morgan Lens

A sterile, ocular contact device attached to IV tubing that floats on irrigating fluid over the eye without contacting the cornea to provide continuous, high-volume lavage for ocular chemical burns or irritants.

Chemical Eye Exposure

An ocular emergency requiring immediate, uninterrupted irrigation with sterile saline or water; alkaline substances ($\text{pH} > 7$) cause deep liquefaction necrosis, while acidic agents ($\text{pH} < 7$) cause superficial coagulative corneal damage.

External Hordeolum (Sty)

An acute, tender, localized erythematous staphylococcal infection of the meibomian glands along the lid margin, managed primarily with warm, moist compresses applied at least 4 times daily.

Chalazion

A chronic, noninfectious inflammatory granuloma of the meibomian glands within the eyelid, presenting as a discrete, swollen, relatively painless nodule on the lid.

Blepharitis

A chronic, bilateral inflammation of the eyelid margins characterized by erythema, pruritus, scale formation, and crusting along the lid edges, managed with baby shampoo lid scrubs.

Epidemic Keratoconjunctivitis (EKC)

A severe, highly contagious adenoviral eye infection transmitted via direct contact, contaminated medical equipment, or swimming pools, presenting with tearing, redness, photophobia, and foreign body sensation.

Acanthamoeba Keratitis

A treatment-resistant parasitic infection of the cornea associated with contact lens wear and contamination from nonsterile water, homemade saline, or poor lens hygiene that can necessitate corneal transplantation.

Keratoconus

A noninflammatory, progressive corneal dystrophy characterized by central corneal stromal thinning and anterior protrusion into a cone shape, producing irregular astigmatism and blurred vision.

Penetrating Keratoplasty

A full-thickness corneal transplantation procedure in which all layers of diseased, opacified, or scarred cornea are excised and replaced with a sutured, clear donor graft.

Cataract

An opacity or clouding within the crystalline lens of the eye that scatters incoming light, resulting in gradual painless vision decline, altered color perception, and nighttime glare.

Phacoemulsification

The modern intraoperative technique for cataract extraction where an ultrasonic handpiece fragments and aspirates the opacified lens core through a self-sealing clear corneal incision before IOL placement.

Postoperative Eye Surgery Precautions

Activity restrictions to prevent spikes in intraocular pressure (IOP), including avoiding heavy lifting, strenuous exertion, bending below waist level, coughing, straining (Valsalva), and sleeping without an eye shield.

Diabetic Retinopathy

A progressive microvascular retinal complication of diabetes mellitus categorized into nonproliferative (microaneurysms, dot/blot hemorrhages, hard exudates) and proliferative stages (abnormal, fragile neovascularization).

Retinal Detachment

An ocular emergency characterized by separation of the neurosensory retina from the underlying retinal pigment epithelium with subretinal fluid accumulation, presenting with photopsia (flashes), floaters, and a painless 'curtain' over the visual field.

Scleral Buckling

An extraocular surgical procedure for retinal detachment where a silicone sponge or band is sutured onto the sclera to indent the ocular wall inward against the detached neurosensory retina.

Age-Related Macular Degeneration (AMD)

A leading cause of irreversible central vision loss divided into dry AMD (slow atrophy of macular cells with yellow drusen accumulation) and wet AMD (rapid central vision loss caused by choroidal neovascularization, leakage, and subretinal scarring).

Amsler Grid Test

A diagnostic self-assessment tool consisting of a printed geometric grid with a central fixation point used to detect macular pathology manifesting as scotomas or metamorphopsia (distorted or wavy lines).

Primary Open-Angle Glaucoma (POAG)

The most common form of glaucoma where aqueous humor drainage channels in the trabecular meshwork become clogged, causing slow, asymptomatic increases in IOP ($22\text{ to }32\,\text{mm\,Hg}$), progressive optic nerve cupping, and peripheral 'tunnel vision.'

Acute Angle-Closure Glaucoma (AACG)

An ophthalmic emergency caused by sudden iris displacement blocking the anterior chamber drainage angle, resulting in rapid IOP elevation (frequently $> 50\,\text{mm\,Hg}$), excruciating eye pain, nausea, vomiting, corneal edema, and rainbow halos around lights.

Argon Laser Trabeculoplasty (ALT)

A noninvasive laser procedure that applies thermal burns to the trabecular meshwork, inducing contraction and scarring to open aqueous outflow channels and lower IOP in open-angle glaucoma.

Endophthalmitis

A severe, vision-threatening intraocular infection of the vitreous cavity caused by bacteria, fungi, or parasites following ocular trauma or surgery, presenting with severe ocular pain, conjunctival injection, photophobia, and rapid vision loss.

Enucleation

The surgical excision of the entire eyeball after severing the extraocular muscles, indicated for intractable ocular pain in a blind eye, extensive trauma, or malignant intraocular tumors (e.g., uveal melanoma).