CONFIRMING DIAGNOSIS Loss of peripheral vision and disk changes confirm that glaucoma is present. Diagnosis is made by:
❑ testing IOP
❑ measuring the visual field and noting changes, such as an enlarged blind spot and loss of peripheral vision field
❑ observing changes in the cup/disk ratio of the optic nerve head.
Relevant diagnostic tests include:
❑ Tonometry (using an applanation tonopen or air puff tonometer) — This test measures the IOP and provides a baseline for reference. Normal IOP ranges from 8 to 21 mm Hg. However, patients who fall within this normal range can develop signs and symptoms of glaucoma, and patients who have abnormally high pressure may have no clinical effects. Fingertip tension is another way to measure IOP. On gentle palpation of closed eyelids, one eye feels harder than the other in acute angle-closure glaucoma.
❑ Slit-lamp examination — The slit lamp facilitates examination of the anterior structures of the eye: the cornea, iris, and lens.
❑ Gonioscopy — By determining the angle of the anterior chamber of the eye, this test enables differentiation between chronic open-angle glaucoma and acute angle-closure glaucoma. The angle is normal in chronic open-angle glaucoma. However, in older patients, partial closure of the angle may occur, so that two forms of glaucoma may co-exist.
❑ Ophthalmoscopy — This test enables the examiner to look at the fundus to establish if there are any cup/disk ratio changes. (See Optic disk changes.) These changes appear later in chronic glaucoma if the disease isn’t brought under control.
❑ Fundus photography — Pictures of the optic nerve head are made to track changes.
❑ Perimetry or visual field tests — These reveal the extent of damage to the optic neurons, signaled by an enlarged blind spot and loss of peripheral vision.
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Source: Professional Guide to Diseases (Eighth Edition), 2005
Corneal abrasion:
Diagnosis
(Handbook of Diseases)
A history of eye trauma or prolonged wearing of contact lenses as well as typical symptoms suggest corneal abrasion. Staining the cornea with fluorescein stain confirms the diagnosis: The injured area appears green when examined with a Wood’s lamp or black light. Slit-lamp examination discloses the depth of the abrasion.
Examining the eye with a flashlight may reveal a foreign body on the cornea; the eyelid must be everted to check for a foreign body embedded under the lid.
Before beginning treatment, a test to determine visual acuity provides a medical baseline and a legal safeguard.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Corneal ulcers:
Diagnosis
(Handbook of Diseases)
A history of trauma or use of contact lenses and a flashlight examination that reveals an irregular corneal surface suggest corneal ulcer. Exudate may be present on the cornea, and a hypopyon (accumulation of white cells in the anterior chamber) may appear as a half-moon.
Fluorescein dye, instilled in the conjunctival sac, delineates the outline of the ulcer. Culture and sensitivity testing of corneal scrapings, which may identify the causative bacteria or fungus, indicate appropriate antibiotic or antifungal therapy.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Premature rupture of the membranes:
Diagnosis
(Handbook of Diseases)
Characteristic passage of amniotic fluid confirms PROM. Physical examination shows amniotic fluid in the va-gina. Examination of this fluid helps determine appropriate management. For example, aerobic and anaerobic cultures and a Gram stain from the cervix reveal pathogenic organisms and indicate uterine or systemic infection. The alkaline pH of fluid collected from the posterior fornix turns nitrazine paper deep blue. (The presence of blood can give a false-positive result.) If a smear of fluid is placed on a slide and allowed to dry, it takes on a fernlike pattern due to the high sodium and protein content of amniotic fluid.
Staining the fluid with Nile blue sulfate reveals two categories of cell bodies. Blue-stained bodies represent shed fetal epithelial cells; orange-stained bodies originate in sebaceous glands. The incidence of prematurity is low when more than 20% of cells stain orange.
Physical examination also determines the presence of multiple pregnancies. Fetal presentation and size should be assessed by abdominal palpation (Leopold’s maneuvers).
Other data determine the fetus’s gestational age:
❑ historic: date of last menstrual period, quickening
❑ physical: initial detection of unamplified fetal heart sound, measurement of fundal height above the symphysis, ultrasound measurements of fetal biparietal diameter
❑ chemical: tests on amniotic fluid such as the lecithin-sphingomyelin (L/S) ratio (an L/S ratio greater than 2.0 indicates pulmonary maturity); foam stability (shake test) also indicates fetal pulmonary maturity.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Glaucoma:
Diagnosis
(Handbook of Diseases)
Loss of peripheral visual field, cupping of the optical disk, and increased IOP are the triad of signs that indicate glaucoma. Relevant diagnostic tests include the following:
❑ Tonometry (using an applanation, Schiøtz, or air-puff tonometer) measures IOP and provides a baseline for reference.
Normal IOP ranges between 8 and 21 mm Hg, but some patients who fall in the normal range develop signs and symptoms of glaucoma. On the other hand, some patients who have abnormally high pressure have no clinical effects.
Fingertip tension is another way to measure IOP. On gentle palpation of closed eyelids, one eye feels harder than the other in acute angle-closure glaucoma.
❑ Slit-lamp examination provides a look at the anterior structures of the eye, including the cornea, iris, and lens.
❑ Gonioscopy, by determining the angle of the anterior chamber of the eye, allows differentiation between chronic open-angle glaucoma and acute angle-closure glaucoma. The angle is normal in chronic open-angle glaucoma. In older patients, partial closure of the angle may also occur, so two forms of glaucoma may coexist.
❑ Ophthalmoscopy provides a look at the fundus, where cupping of the optic disk is visible in chronic open-angle glaucoma. This change appears later in chronic angle-closure glaucoma if the disease isn’t brought under control. A pale disk appears in acute angle-closure glaucoma.
❑ Perimetry or visual field tests help evaluate the extent of chronic open-angle deterioration by determining peripheral vision loss.
❑ Fundus photography can monitor the disk for any changes.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
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