Visual Impairment(Glaucoma & Cataract)

Dr. Belal M. Hijji, RN, PhD

May 18 & 21, 2011

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Learning Outcomes

At the end of this lecture, students will be able to:• Recognise the causes and effects of visual impairment

on an individual.• Define glaucoma and identify its clinical manifestations.• Identify diagnostic tests for assessment of glaucoma and

cataract.• Discuss the medical and nursing management of

patients with glaucoma and cataract.

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Introduction

• Impaired vision affects an individual’s independence in self-care, work and lifestyle choices, sense of self-esteem, safety, ability to interact with society and the environment, and overall quality of life. Many of the leading causes of visual impairment and blindness are cataracts, glaucoma, macular degeneration, and diabetic retinopathy. Younger people are also at risk for eye disorders, particularly traumatic injuries.

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Glaucoma

• Glaucoma is a group of ocular conditions characterized by optic nerve damage which is related to high IOP caused by congestion of aqueous humor in the eye.

• Glaucoma is one of the leading causes of irreversible blindness in the world. So far, there is no cure for glaucoma.

Clinical Manifestations• Most patients are unaware that they have the disease

until they have experienced visual changes and vision loss.

• Patients experiences blurred vision or “halos” around lights, difficulty focusing, difficulty adjusting eyes in low lighting, loss of peripheral vision, aching or discomfort around the eyes, and headache.

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Assessment and Diagnostic Findings

• The patient’s ocular and medical history must be detailed to investigate the history of predisposing factors.

• The major types of examinations are: tonometry to measure the IOP, ophthalmoscopy to inspect the optic nerve, gonioscopy and perimetry to assess the visual fields.

• Changes in the optic nerve significant for diagnosis are pallor and cupping of the optic nerve disc. Cupping is characterized by exaggerated bending of the blood vessels as they cross the optic disc, resulting in an enlarged optic cup that appears more basinlike compared with a normal cup.

• As the optic nerve damage increases, visual perception in the area is lost.

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Gonioscopy describes the use of a gonioscope in conjunction with a slit lamp or operating microscope to gain a view of the iridocorneal angle, or the anatomical angle formed between the eye's cornea and iris.

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Medical Management

• Treatment aims at preventing optic nerve damage through medical therapy, laser or non-laser surgery, or a combination.

• Lifelong therapy is indicated as glaucoma is not curable. Optic nerve damage is irreversible. However, further damage can be controlled by maintaining an IOP within an acceptable range (10-21 mmHg).

• The initial target for IOP reduction is typically set at 30% lower than the current pressure. If there is evidence of progressive damage, the target IOP is again lowered until the optic nerve shows stability.

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Pharmacologic Therapy

• The IOP lowering systemic and topical medications. • The patient is usually started on the lowest dose of

topical medication (beta-blockers) and then advanced to increased concentrations until the desired IOP level is reached and maintained.

• One eye is treated first, with the other eye used as a control; once efficacy has been established, treatment of the fellow eye is started.

• If the IOP is elevated in both eyes, both are treated. • When results are not satisfactory, a new medication is

substituted. • The main markers of the efficacy of the medication in

glaucoma control are lowering of the IOP to the target pressure, appearance of the optic nerve head, and the visual field.

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• Several types of ocular medications are used to treat glaucoma by decreasing aqueous humor production and/ or increasing aqueous fluid outflow between the iris and lens. These include alpha adrenergic agonists (apraclonidine), beta-blockers (timolol), adrenergic agonists (epinephrine), miotics (pilocarpine), carbonic anhydrase inhibitors (acetazolamide), and prostaglandins (latanoprost). All these medications (except pilocarpine) reduce aqueous humor production. Pilocarpine increases aqueous fluid outflow causing miosis (constriction of the pupil).

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Surgical Management

• In laser trabeculoplasty for glaucoma, laser burns promote outflow of aqueous humor and decreasing IOP.

• The procedure is indicated when IOP is inadequately controlled by medications.

• A serious complication of this procedure is a transient rise in IOP (usually 2 hours after surgery) that may become persistent. IOP assessment in the immediate postoperative period is essential.

• In laser iridotomy for pupillary block glaucoma, an opening is made in the iris to eliminate the pupillary block.

• Potential complications are burns to the cornea, lens, or retina; transient elevated IOP; closure of the iridotomy; uveitis (iritis); and blurring. Pilocarpine is usually prescribed to prevent closure of the iridotomy.

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Nursing Management

• Teaching patients about glaucoma care– The lifelong therapeutic regimen mandates patient

education. – Nurses should stress the importance of strict adherence to

the medication regimen. – Nurses encountering patients with glaucoma as a

secondary diagnosis should assess their level of knowledge and compliance with the therapeutic regimen.

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• Continuing glaucoma care at home– For patients with severe glaucoma, referral to services that

assist the patient in performing customary activities may be needed.

– The loss of peripheral vision impairs mobility the most. These patients need to be referred to low vision and rehabilitation services.

– Reassurance and emotional support are important aspects of care.

– The family must be integrated into the plan of care, and family members should be encouraged to screen for glaucoma.

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Cataracts

• A cataract is a lens opacity or cloudiness that can affect one or both eyes.

• According to the World Health Organization, cataract is the leading cause of blindness in the world.

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Pathophysiology• Cataracts can develop at any age for a variety of causes

including aging, retinal surgery, infections, corticosteroids, smoking, poor nutrition, obesity, dehydration, trauma, and DM.

• The nuclear, cortical, and posterior subcapsular cataracts are the most common types and are defined by their location in the lens.

• A nuclear cataract is associated with myopia (defective vision of distant objects), which worsens when the cataract progresses. Dense cataract severely blurs [ البصر [يغشىvision.

• A cortical cataract involves the anterior, posterior, or the periphery of the cortex of the lens. Vision is worse in very bright light.

• Posterior subcapsular cataracts occur in front of the posterior capsule. In some cases, it is associated with prolonged corticosteroid use, inflammation, or trauma. Near vision is diminished, and the eye is increasingly sensitive to glare [ساطع] from bright light.

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Clinical Manifestations

• Painless, blurry vision is characteristic of cataracts. • Light scattering is common, and the individual

experiences reduced contrast sensitivity, sensitivity to glare, and reduced visual acuity, dimmer surroundings (as if glasses need cleaning), diplopia, and brunescens (color values shift to yellow-brown).

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Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the colour and brightness of the object and other objects within the same field of view.

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Assessment and Diagnostic Findings

• Decreased visual acuity is directly proportionate to cataract density.

• The Snellen visual acuity test, ophthalmoscopy, and slitlamp biomicroscopic examination are used to establish the degree of cataract formation.

• The degree of lens opacity does not always correlate with the patient’s functional status.

• Some patients can perform normal activities despite clinically significant cataracts. Others with less lens opacification have a disproportionate decrease in visual acuity; hence, visual acuity is an imperfect measure of visual impairment.

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Medical Management• No nonsurgical treatment cures cataracts. • In the early stages of cataract development, glasses,

contact lenses, strong bifocals [ البؤرة ثنائية or ,[النظارةmagnifying lenses may improve vision.

• Reducing glare with proper light and appropriate lighting can facilitate reading. Mydriatics (atropine) can be used as short-term treatment to dilate the pupil and allow more light to reach the retina.

• Intracapsular cataract extraction. The entire lens (ie, nucleus, cortex, and capsule) is removed, and fine sutures close the incision. ICCE is infrequently used; it is indicated when there is a need to remove the entire lens, such as with a subluxated cataract (ie, partially or completely dislocated lens).

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• Extracapsular surgery. Extracapsular cataract extraction (ECCE) achieves the intactness of smaller incisional wounds (less trauma to the eye) and maintenance of the posterior capsule of the lens, reducing postoperative complications, particularly retinal. In ECCE, a portion of the anterior capsule is removed, allowing extraction of the lens nucleus and cortex.

• Lens replacement. After removal of the crystalline lens which focuses light on the retina, it must be replaced for the patient to see clearly.

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Nursing Management

• Providing preoperative care– To reduce the risk for retrobulbar hemorrhage,

anticoagulation therapy is withheld, if medically appropriate. Aspirin should be withheld for 5 to 7 days, nonsteroidal anti-inflammatory medications (NSAIDs) for 3 to 5 days, and warfarin (Coumadin) until the prothrombin time of 1.5 is almost reached.

– Dilating drops are administered every 10 minutes for four doses at least 1 hour before surgery. Additional dilating drops may be administered in the operating room (immediately before surgery) if the affected eye is not fully dilated. Prophylactic antibiotic, corticosteroid, and NSAID drops may be used.

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• Providing postoperative care– The nurse provides the patient with verbal and written

instruction regarding how to protect the eye, administer medications, recognize signs of complications, and obtain emergency care.

– The nurse instructs the patient regarding home care (Chart 58-6, page 1764)

– The nurse also explains that there is minimal discomfort after surgery and instructs the patient to take a mild analgesic agent PRN. Antibiotic, anti-inflammatory, and corticosteroid eye drops or ointments are prescribed postoperatively.