Wednesday, December 31, 2014

The eyes : hordeolum and hyperopia .

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hordeolum A bacterial INFECTION of a gland or an eyelash follicle along the edge of the eyelid, commonly known as a stye. A hordeolum causes swelling, redness, PAIN, and a discharge that leaves a crusty layer on the eyelids during sleep. The doctor can usually diagnose hordeolum by its presenta- tion. BLEPHARITIS (infection of the inside surface of the eyelid) and CONJUNCTIVITIS (infection of the conjunctiva, the membrane lining the eyelids) may instigate, accompany, or follow hordeolum. The doctor often chooses to anesthetize the area and lance (make tiny punctures or incisions under sterile conditions) the hordeolum to drain its contents and relieve the pressure. Further treatment is ophthalmic ANTIBIOTIC MEDICATIONS, typically in ointment form, applied to the area. Sometimes oral antibiotic medications are also necessary. Warm, moist compresses soothe the irritated tissues and help draw out any remaining pus.

Most hordeola clear up in 7 to 10 days with treatment and heal without residual consequences. A hordeolum does not itself cause VISION IMPAIRMENT, though untreated hordeola can lead to significant EYE problems if the infection spreads to other structures of the eye. Some people experience recurring hordeola, while others experience only a single episode. A hordeolum may also form the basis for a CHALAZION (painless nodule) to develop in its place.

See also BACTERIA; ECTROPION; ENTROPION.

hyperopia A refractive error, commonly called farsightedness, in which the EYE has difficulty focusing on near objects. Hyperopia results when the focal point of lightwaves entering the eye extends past the RETINA, causing the images the retina registers to be blurred. The refractive error occurs because the distance from the front to the back of the eye is shorter than normal. Symptoms of hyperopia include

• squinting when reading or doing close work

• HEADACHE

• fatigued eye muscles (aching around the eyes)

• blurred vision when looking at near objects yet clear vision when looking at distant objects

CORRECTIVE LENSES (eyeglasses or contact lenses) can compensate for hyperopia by altering the focal point of lightwaves so it falls directly on the retina. They do so by refracting (bending) the lightwaves outward. REFRACTIVE SURGERY, which permanently alters the shape of the CORNEA, can provide refractive correction for people with mild to moderate hyperopia. Hyperopia sometimes occurs following refractive surgery for MYOPIA (nearsightedness) as a consequence of overcorrection. Eye professionals denote refractive corrections in units of measure called diopters. For hyperopia, the expression of diopter is a positive number. Corrective lenses for hyperopia have a magnifying appearance that make the eyes look bigger than they are.

Hyperopia is less common than myopia, affecting about 20 to 25 percent of adults. Few people who have hyperopia have greater than +6 diopters of refractive error, so nearly always corrective measures result in normal VISUAL ACUITY.

See also ASTIGMATISM; PRESBYOPIA; REFRACTIVE ERRORS.