Table 17-7  Prevalence of optic nerve and/or visual field damage at different levels of ocular hypertension

Modified from Anderson DR: Surv Ophthalmol 21:479, 1977.

NA, Not applicable.

Treatment

An ocular hypertensive individual requires periodic examinations, including tonometry, perimetry, and optic disc assessment. Blueyellow perimetry or frequency-doubled perimetry may be helpful in identifying the earliest glaucomatous visual field defects, although these techniques may have a more significant noise level that reduces specificity. Stereoscopic optic disc photographs provide baseline information against which one can determine changes in the optic nerve over time. Nerve fiber layer photographs may also be useful. Other, newer digital imaging tests such as confocal scanning laser ophthalmoscopy, ocular coherence tomography, and/or scanning laser polarimetry are just beginning to show evidence of detecting early optic nerve damage and change.406 Therapy should be instituted if early damage is detected or if the patient appears to be at high risk for developing POAG based on the risk factors identified above. Many clinicians institute medical treatments

if the IOP is 30 mmHg or greater, noting that the prevalence of glaucoma at this pressure level is 11–29% (Table 17-7).12,15,408,409

It may also be appropriate to recommend therapy for individuals with IOPs in the middle-to-upper 20s who also have one or more risk factors (Box 17-3). Following are other possible indications for treatment:

1.A one-eyed patient. Many clinicians are more aggressive in treating one-eyed patients.

2.A young patient. Some ophthalmologists prescribe medical treatment more rapidly for young patients who will be exposed to high pressure for many years.This may be questionable reasoning because, often, young optic nerves are more resistant to the effects of elevated IOP than are older ones.

3.Unreliable visual fields or optic disc assessment.The entire concept of following ocular hypertensive patients without

Box 17-3  Differential diagnosis of normal-tension glaucoma

I.Glaucoma

A.Elevated intraocular pressure (IOP) not detected

1.Undetected wide diurnal variation

2.Low scleral rigidity

3.Systemic medication that may mask elevated IOP (e.g., recent-blocker treatment)

4.Past systemic medication that may have elevated IOP

5.Elevation of IOP in supine position only

B.Glaucoma in remission

1.Past corticosteroid administration

2.Pigmentary glaucoma410

3.Associated with past uveitis or trauma

4.Glaucomatocyclitic crisis

5.Burned-out primary open-angle glaucoma

II.Optic nerve damage

A.Congenital optic nerve conditions45

1.Pits

2.Colobomas

3.Tilted discs

B.Ischemic optic neuropathy

1.Arteritic

2.Non-arteritic

C.Compressed lesions

1.Tumors

2.Aneurysms

3.Cysts

4.Chiasmatic arachnoiditis

D.Optic nerve drusen

E.Demyelinating conditions

F.Inflammatory diseases

G.Hereditary optic atrophy

H.Toxic drugs or chemicals

III.Ocular disorders

A.Myopia

B.Retinal degeneration

C.Myelinated nerve fibers

D.Branch vascular occlusions

E.Choroidal nevus or melanoma

F.Choroidal rupture

G.Retinoschisis

H.Chorioretinal disease

IV. Systemic vascular conditions

A.Anemia

B.Carotid artery obstruction

C.Acute blood loss

D.Arrhythmia

E.Hypotensive episodes V. Miscellanenous

A.Hysteria

B.Artifact of visual field testing

treatment rests on the clinician’s ability to detect early damage. If this is not possible, treatment is indicated.

4.A patient who is content with treatment initiated by another physician and who is tolerating the medication well.

5.An ocular hypertensive patient who desires treatment.

6.An ocular hypertensive patient who has developed a vascular occlusion in either eye.

Regardless of the risk factors and the actual risks of developing open-angle glaucoma, the clinician should remember that these patients do not yet have disease, so their own thoughts and concepts