Summary Points About Blepharitis

A common inflammation, blepharitis produces a red-rimmed appearance of the margins of the eyelids. In many cases, it’s chronic and bilateral and affects upper and lower lids. 

Seborrheic blepharitis is characterized by waxy scales and is common in older adults and in those with red hair. 

Staphylococcal (ulcerative) blepharitis is characterized by tiny ulcerated areas along the lid margins. 

Both types may coexist.

Blepharitis tends to recur and become chronic. It can be controlled if treatment begins before the onset of ocular involvement.

Causes
Seborrheic blepharitis generally results from seborrhea of the scalp, eyebrows, or ears; ulcerative blepharitis results from Staphylococcus aureus infection. (People with this infection may also tend to develop chalazions and styes.)

Signs and symptoms
Signs and symptoms of blepharitis include itching, burning, foreign-body sensation, and sticky, crusted eyelids on waking. This constant irritation results in unconscious rubbing of the eyes (causing reddened rims) or continual blinking. Other signs include waxy scales in seborrheic blepharitis; flaky scales on lashes, loss of lashes, and ulcerated areas on lid margins in ulcerative blepharitis.

Brief Summary of Conjunctivitis

Hyperemia of the conjunctiva from infection, allergy, or chemical reactions characterizes conjunctivitis. Bacterial and viral conjunctivitis are highly contagious but are also self-limiting after 2 weeks. Chronic conjunctivitis may result in degenerative changes to the eyelids. In the Western hemisphere, conjunctivitis is probably the most common eye disorder.

Causes
The most common causative organisms are the following:

• bacterial: Staphylococcus aureus, Streptococcus pneumoniae, Neisseria gonorrhoeae, Neisseria meningitidis
• chlamydial: Chlamydia trachomatis (inclusion conjunctivitis)
• viral: adenovirus types 3, 7, and 8; herpes simplex virus type 1.

Other causes include allergic reactions to pollen, grass, topical medications, air pollutants, and smoke; occupational irritants (acids and alkalies); rickettsial diseases (Rocky Mountain spotted fever); parasitic diseases caused by Phthirus pubis and Schistosoma haematobium; and, rarely, fungal infections.

Vernal conjunctivitis (also called seasonal or warm-weather conjunctivitis) results from allergy to an unidentified allergen. This form of conjunctivitis is bilateral; it usually begins before puberty and persists for about 10 years. Sometimes it’s associated with other signs and symptoms of allergy commonly related to grass or pollen sensitivity.

An idiopathic form of conjunctivitis may be associated with certain systemic diseases, such as erythema multiforme, chronic follicular conjunctivitis (orphan’s conjunctivitis), thyroid disease, and Stevens-Johnson syndrome. Conjunctivitis may be secondary to pneumococcal dacryocystitis or canaliculitis from candidal infection.

Introduction to Glaucoma

Glaucoma is a group of disorders characterized by intraocular pressure (IOP) high enough to damage the optic nerve. If untreated, it leads to gradual peripheral vision loss and, ultimately, blindness.

Glaucoma occurs in several forms: 

• chronic open-angle (primary), 
• acute angle-closure, 
• low tension (normal IOP that’s too high for a particular person), 
• congenital (inherited as an autosomal recessive trait), and 
• secondary to other causes.

Glaucoma is the second most common cause of blindness in the United States. About 2.5 million Americans are afflicted with the disease, but only 1 million know that they have it. Its incidence is highest among blacks, and it’s the single most common cause of blindness in that group. The visual prognosis is good with early treatment.

Causes
The cause of glaucoma varies according to the type of disorder:

Chronic open-angle glaucoma results from overproduction of aqueous humor or from obstructed outflow of aqueous humor through the trabecular meshwork or the canal of Schlemm. This form of glaucoma frequently runs in families and affects 90% of all patients with glaucoma.

Acute angle-closure (narrow-angle) glaucoma results from obstructed outflow of aqueous humor caused by anatomically narrow angles between the anterior iris and the posterior corneal surface, shallow anterior chambers, a thickened iris that causes angle closure on pupil dilation, or a bulging iris that presses on the trabeculae, closing the angle. Adhesions in the angle, referred to as peripheral anterior synechiae, may be the cause.

Secondary glaucoma can result from uveitis, trauma, or drugs such as steroids. Neovascularization in the angle can result from vein occlusion or diabetes.

Introduction to Retinal Detachment

When the sensory retina splits from the retinal pigment epithelium, retinal detachment occurs, creating a subretinal space. This space then fills with fluid, called subretinal fluid. Retinal detachment usually involves only one eye but may involve the other eye later.
Surgical reattachment is often successful. However, the prognosis for good vision depends on the area of the retina that’s been affected.

Causes
Any retinal tear or hole allows the liquid vitreous to seep between the retinal layers, separating the retina from its choroidal blood supply. In adults, retinal detachment usually results from degenerative changes of aging, which cause a spontaneous retinal hole.
Predisposing factors include myopia, cataract surgery, and trauma. Perhaps the influence of trauma explains why retinal detachment is twice as common in males.
Retinal detachment may also result from seepage of fluid into the subretinal space (because of inflammation, tumors, or systemic diseases) or from traction that’s placed on the retina by vitreous bands or membranes (from proliferative diabetic retinopathy, posterior uveitis, or a traumatic intraocular foreign body).
Retinal detachment is rare in children but occasionally can develop as a result of retinopathy of prematurity, tumors (retinoblastomas), or trauma. It can also be inherited, usually in association with myopia.

Signs and symptoms
Initially, the patient may complain of floating spots and recurrent flashes of light. But as detachment progresses, gradual, painless vision loss may be described as a veil, curtain, or cobweb that eliminates a portion of the visual field.

Chalazion - Clinical Features & Management

A common eye disorder, a chalazion is a granulomatous inflammation of a meibomian gland in the upper or lower eyelid. This disorder is characterized by localized swelling and usually develops slowly over several weeks.
A chalazion may become large enough to press on the eyeball, producing astigmatism; a large chalazion seldom subsides spontaneously and may have to be incised and curetted surgically. A person susceptible to developing chalazia may have more than one because the upper and lower eyelids contain many meibomian glands. If a chalazion becomes persistent and chronic, a neoplasm should be ruled out by biopsy.

Pathophysiology:
Obstruction of the meibomian (sebaceous) gland duct causes a chalazion.

Signs and symptoms
A chalazion occurs as a painless, hard lump that usually points toward the conjunctival side of the eyelid. Eversion of the lid reveals a red elevated area on the conjunctival surface.

Diagnosis
Visual examination and palpation of the eyelid reveal a small bump or nodule. Persistently recurrent chalazia, especially in an adult, necessitate a biopsy to rule out meibomian cancer.

Introduction to Keratitis

Keratitis, also known as inflammation of the cornea, may be acute or chronic, superficial or deep. Superficial keratitis is fairly common and may develop at any age. The prognosis is good with treatment. Untreated, recurrent keratitis may lead to blindness.

Causes
Keratitis may result from exposure (as in Bell’s palsy where the eyelids don’t close), wearing contact lenses for prolonged periods (overnight), or corneal trauma. It may also result from infection by herpes simplex virus, type 1 (known as dendritic keratitis because of a characteristic branched lesion of the cornea resembling the veins of a leaf). Less commonly, it stems from bacterial or fungal infection; rarely, from congenital syphilis.

Signs and symptoms
Unilateral keratitis may produce pain, tearing, and photophobia. If the infection is in the center of the cornea, it may produce blurred vision. Left untreated, corneal opacities can occur. When keratitis results from exposure, it usually affects the lower portion of the cornea.

Diagnosis
A slit-lamp examination reveals the depth of the keratitis. If it’s due to herpes simplex virus, staining the eye with a fluorescein strip produces one or more small branchlike (dendritic) lesions; touching the cornea with cotton reveals reduced corneal sensation. Vision testing may show slightly decreased acuity. The patient history may reveal a recent infection of the upper respiratory tract accompanied by cold sores.

Macular degeneration

Macular degeneration, which is atrophy or degeneration of the macular disk, accounts for about 12% of all cases of blindness in the United States and for about 17% of new cases of blindness. It’s one of the causes of severe irreversible loss of central vision in people older than age 50. It affects slightly more women than men.

Types of Macular Degenaration
Two types of age-related macular degeneration occur. 

The dry, or atrophic, form is characterized by atrophic pigment epithelial changes and is usually associated with a slow, progressive distortion of straight lines or edges and central visual loss. 

The wet, or exudative, form causes rapid onset of visual impairment. It’s characterized by subretinal neovascularization that causes leakage, hemorrhage, and fibrovascular scar formation, which produce significant loss of central vision.

Pathophysiology

Age-related macular degeneration results from the formation of drusen (clumps of epithelium) or subretinal neovascular membrane in the macular region. It may be hereditary. Cigarette smoking and lack of antioxidants, such as vitamins C and E, may also enhance occurrence.

Underlying pathologic changes occur primarily at the level of the retinal pigment epithelium, Bruch’s membrane, and choriocapillaris in the macular region. Drusen (bumps), which are common in elderly people, appear as yellow deposits beneath the pigment epithelium and may be prominent in the macula.

Corneal abrasion

Commonly caused by a foreign body, a corneal abrasion is a scratch on the surface epithelium of the cornea. An abrasion or foreign body in the eye is the most common eye injury. With treatment, the prognosis is usually good.

Causes
A corneal abrasion usually results from a foreign body, such as a cinder or a piece of dust, dirt, or grit, which becomes embedded under the eyelid. Even if the foreign body is washed out by tears, it may still injure the cornea.
A small piece of metal that gets in the eyes of workers who don’t wear protective glasses quickly forms an abrasion and then forms a rust ring on the cornea. Abrasions also commonly occur in the eyes of people who fall asleep wearing hard contact lenses. A corneal scratch produced by a fingernail, a piece of paper, or another organic substance may cause a persistent lesion. The epithelium doesn’t always heal properly, and a recurrent corneal erosion may develop, with delayed effects more severe than those of the original injury.

Signs and symptoms
Typically, corneal abrasions produce redness, increased tearing, a sensation of “something in the eye” and, because the cornea is richly endowed with nerve endings from the trigeminal nerve (cranial nerve V), pain disproportionate to the size of the injury. A corneal abrasion may affect visual acuity, depending on the size and location of the injury.

Brief Summary of Cataract

Introduction: 

A common cause of vision loss, a cataract is a gradually developing opacity of the lens or lens capsule of the eye. Cataracts commonly occur bilaterally, with each progressing independently. Exceptions are traumatic cataracts, which are usually unilateral, and congenital cataracts, which may remain stationary.
Cataracts are a part of aging and are most prevalent in patients older than age 70. Surgical intervention improves vision in 95% of affected people.

Causes
Cataracts have various causes, depending on their type:
Senile cataracts develop in elderly patients, probably because of degenerative changes in the chemical state of lens proteins.
Congenital cataracts occur in neonates as genetic defects or as a result of maternal rubella during the 1st trimester.
Traumatic cataracts develop after a foreign body injures the lens with sufficient force to allow aqueous or vitreous humors to enter the lens capsule.
Complicated cataracts develop as secondary effects in patients with uveitis, glaucoma, retinitis pigmentosa, or a detached retina or in the course of a systemic disease, such as diabetes, hypoparathyroidism, or atopic dermatitis. These cataracts can also result from exposure to ionizing radiation or infrared rays.
Toxic cataracts result from prolonged drug or chemical toxicity from prednisone, ergot alkaloids, naphthalene, or phenothiazines; they also result from excessive exposure to sunlight.