Common eye disorders

Focus Topic: Eye disorders

Cataracts, glaucoma, retinal detachment, and vascular retinopathies are common eye disorders.

Eye disorders: Retinal detachment

In retinal detachment, the retinal layers split, 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 almost always successful. However, prognosis for good vision depends on the affected retinal area.

What causes it

Predisposing factors include high myopia and cataract surgery. The most common causes are degenerative changes in the retina or vitreous humor. Other causes include:

  • trauma or inflammation
  • systemic diseases such as diabetes mellitus
  • rarely, retinopathy of prematurity or tumors.

Pathophysiology

Any retinal tear or hole allows the vitreous humor to seep between the retinal layers, separating the retina from its choroidal blood supply. Retinal detachment may also result from seepage of fluid into the subretinal space or from traction that’s placed on the retina by vitreous bands or membranes. (See Understanding retinal detachment.)

Understanding retinal detachment

Eye disorders

 

What to look for

Symptoms of retinal detachment include:

  • floaters
  • light flashes
  • sudden, painless vision loss the patient may describe as a curtain that eliminates a portion of the visual field.

What tests tell you

  • Ophthalmoscopic examination through a well-dilated pupil confirms the diagnosis. In severe detachment, examination reveals folds in the retina and a ballooning out of the area.
  • Indirect ophthalmoscopy is also used to search the retina for tears and holes.
  • Ocular ultrasonography may be necessary if the lens is opaque or the vitreous humor is cloudy.

How it’s treated

Depending on the location and severity of the detachment, treatment may include:

  • Placing the patient on bed rest and sedation to restrict eye movements. If the patient’s macula is threatened, he may need his head positioned so the tear or hole is below the rest of the eye.
  • A hole in the peripheral retina can be treated with cryotherapy; a hole in the posterior portion, with laser therapy.
  • Retinal detachment rarely heals spontaneously. Surgery —
    including scleral buckling, pneumatic retinopexy, or vitrectomy,
    or a combination of these procedures — can reattach the retina.

What to do

  • Provide emotional support because the patient may be understandably distraught about his loss of vision.
  • Position the patient face down if gas has been injected to maintain pressure on the retina.
  • Evaluate the patient. With successful treatment, he’ll experience restored vision without impairment. He should follow up as directed. (See Retinal detachment teaching tips.)

Retinal detachment teaching tips

  • If the patient will undergo laser surgery, explain that he may have blurred vision for several days afterward.
  • Show the patient having scleral buckling surgery how to instill eyedrops properly. After surgery, remind him to lie in the position recommended by the doctor.
  • Instruct the patient to rest and to avoid driving, bending, heavy lifting, and other activities that affect intraocular pressure for several days after eye surgery. Discourage activities that could cause the patient to bump the eye.
  • Review early symptoms of retinal detachment, and emphasize the need for immediate treatment.

Eye disorders: Vascular retinopathies

Vascular retinopathies are noninflammatory disorders that result from disruption of the eye’s blood supply. The four distinct types of vascular retinopathy are central retinal artery occlusion, central retinal vein occlusion, diabetic retinopathy, and hypertensive retinopathy.

Eye disorders: Backup on the central artery

Central retinal artery occlusion typically causes permanent blindness. However, some patients experience resolution within hours of treatment and regain partial vision.

What causes it

Central retinal artery occlusion may be idiopathic (no known cause) or result from:

  • embolism, atherosclerosis, or infection (such as syphilis or rheumatic fever)
  • conditions that retard blood flow, such as temporal arteritis, massive hemorrhage, or carotid blockages by atheromatous plaques.

Eye disorders: In the same vein

Central retinal vein occlusion can result from:

  • trauma or external compression of the retinal vein
  • diabetes, phlebitis, thrombosis, atherosclerosis, glaucoma, polycythemia vera, or sickling hemoglobinopathies.

Eye disorders: It’s all in a name

The names of the two types of vascular retinopathy indicate their causes. Diabetic retinopathy can stem from diabetes, and hypertensive retinopathy can result from prolonged hypertension.

Pathophysiology

Central retinal artery occlusion and central retinal vein occlusion occur when a retinal vessel becomes obstructed. The diminished blood flow causes vision deficits.

Eye disorders: Diabetes dysfunction

Diabetic retinopathy results from the microcirculatory changes that occur with diabetes. These changes occur more rapidly in poorly controlled diabetes. Diabetic retinopathy may be nonproliferative or proliferative; proliferative diabetic retinopathy produces fragile new blood vessels (neovascularization) on the disk and elsewhere in the fundus.

[sociallocker]

Eye disorders: Hypertension havoc

In hypertensive retinopathy, prolonged hypertension produces retinal vasospasm and consequent damage to and narrowing of the arteriolar lumen.

What to look for

Signs and symptoms of vascular retinopathies depend on the cause:

  • central retinal artery occlusion — sudden painless, unilateral loss of vision (partial or complete) that doesn’t pass; this may follow transient episodes of unilateral loss of vision
  • central retinal vein occlusion — reduced visual acuity that’s painless except when it results in secondary neovascular glaucoma (uncontrolled proliferation of blood vessels)
  • diabetic retinopathy — in nonproliferative form, possibly no signs or symptoms, or loss of central visual acuity and diminished night vision from fluid leakage into the macular region; in proliferative form, sudden vision loss from vitreous hemorrhage or macular distortion or retinal detachment from scar tissue formation
  • hypertensive retinopathy — signs and symptoms dependent on the location of retinopathy (for example, blurred vision if located near the macula)

Eye disorders

 

What tests tell you

Tests depend on the type of vascular retinopathy. (See Diagnostic tests for vascular retinopathies.)

How it’s treated

Treatment depends on the cause of the retinopathy.

Eye disorders: Central retinal artery occlusion

No known treatment exists, although the practitioner may attempt to release the occlusion into the peripheral circulation. To reduce IOP, therapy includes acetazol amide, eyeball massage using a Goldman-type gonioscope and, possibly, anterior chamber paracentesis. The patient may receive inhalation therapy of carbogen (95% oxygen and 5% carbon dioxide) to improve retinal oxygenation. The patient may also receive inhalation treatments hourly for 48 hours, so he should be hospitalized for careful monitoring.

Eye disorders: Central retinal vein occlusion

Anticoagulant administration is the treatment of choice. The practitioner may also recommend laser photocoagulation for patients with widespread capillary nonperfusion to reduce the risk of neovascular glaucoma.

Eye disorders: Diabetic retinopathy

Treatment includes controlling the patient’s blood glucose levels and laser photocoagulation to cauterize weak, leaking blood vessels. If a vitreous hemorrhage occurs when one of these weak blood vessels breaks and it isn’t absorbed in 3 to 6 months, the patient may undergo vitrectomy to restore partial vision.

Eye disorders: Hypertensive retinopathy

Treatment consists of controlling the patient’s blood pressure.

What to do

  • Arrange for immediate ophthalmologic evaluation when a patient complains of sudden, unilateral loss of vision. A delay in treatment may result in permanent blindness.
  • Administer acetazolamide I.M. or I.V. as ordered. During inhalation therapy, monitor vital signs carefully and discontinue if blood pressure fluctuates markedly or if the patient becomes arrhythmic or disoriented. Monitor the patient’s blood pressure if he complains of occipital headache or blurred vision.
  • Evaluate the patient. After successful therapy, the patient with a chronic illness should receive follow-up care as directed and comply with the treatment regimen.
  • A patient with diabetes should understand the need for a stable blood glucose level.
  • A patient with hypertension should keep his blood pressure in a safe range.
  • If vision worsens, the patient should seek immediate medical attention and follow safety precautions to prevent injury. (See Vascular retinopathy teaching tips.)

Vascular retinopathy teaching tips

  • Encourage the patient to comply with prescribed diet, exercise, and medication regimens to minimize the risk of diabetic retinopathy.
  • Advise the patient to receive regular ophthalmologic examinations.
  • For the patient with hypertensive retinopathy, stress the importance of complying with antihypertensive therapy.

Removing obstacles

  • Maintain a safe environment for a patient with vision impairment, and teach him how to make his home safer (by removing obstacles and throw rugs, for instance).
[/sociallocker]

FURTHER READING/STUDY:

Resources: