Osmosis from Elsevier - Legal blindness: Clinical Nursing Care
Legal blindness is defined by a central visual acuity of 20/200 or less in the better-seeing eye or a peripheral visual field of 20° or less. Despite severe visual impairment, many legally blind individuals retain some vision. The visual process begins in the eye, where light is focused onto the retina, converted into electrical impulses, and processed by the brain. Common causes of legal blindness include cataracts, macular degeneration, glaucoma, diabetic retinopathy, and congenital factors. Risk factors include being female, over 50, or having systemic diseases like diabetes. Legal blindness can result from eye structure abnormalities or central nervous system issues, leading to vision loss and potentially circadian rhythm disorders.
Diagnosis involves history taking, visual acuity testing, perimetry, tonometry, and fundoscopy. Treatment focuses on addressing underlying causes and includes low vision rehabilitation and adaptive equipment like corrective lenses and magnification devices. Nursing care aims to ensure client safety and provide supportive care, involving orientation to the environment, assistance with daily activities, and psychosocial support. Education for clients and families includes treatment plans, safety strategies, and resource referrals. Rehabilitation may involve assistive technology and training in daily living skills.
Key Points:
- Legal blindness is defined by specific visual acuity and field criteria.
- Common causes include cataracts, glaucoma, and diabetic retinopathy.
- Diagnosis involves comprehensive eye exams and visual field testing.
- Treatment includes addressing causes, rehabilitation, and adaptive devices.
- Nursing care focuses on safety, support, and client education.
Details:
1. 🔍 Understanding Legal Blindness
- Legal blindness is defined by a central visual acuity of 20/200 or less in the better seeing eye, meaning the person sees at 20 feet what a person with normal vision sees at 200 feet.
- A peripheral visual field of 20 degrees or less also qualifies as legal blindness, indicating a significant restriction in side vision.
- Despite the classification, many legally blind individuals retain some vision, which can vary widely in degree and impact on daily activities. For example, some might distinguish shapes and colors, while others could be sensitive to light.
- Legal blindness can significantly affect daily tasks and independence, necessitating adaptations or assistive technologies, such as screen readers or magnification devices.
- Assessments for legal blindness typically involve both visual acuity tests and visual field tests to determine the extent of vision impairment.
2. 👁️ Physiology of Vision
- The visual process begins with the eye's outer fibrous layer, including the cornea and sclera, which controls and focuses light entry.
- Light passes through the cornea, which offers most of the eye's focusing power, to the lens, which fine-tunes focus for clear vision.
- The lens adjusts its shape for near and distant focus, directing light rays precisely onto the retina.
- The retina contains two types of photoreceptors: rods, which handle low-light vision, and cones, which are responsible for color and detail.
- Photoreceptors convert light into electrical impulses that travel via the optic nerve to the visual cortex.
- The visual cortex integrates impulses from both eyes, synthesizing them into a singular, coherent image, while also processing depth, motion, and context.
3. 🩺 Causes and Risk Factors
- Legal blindness can be caused by various eye conditions, with cataracts, age-related macular degeneration, glaucoma, and diabetic retinopathy being the most common.
- Eye infections, such as trachoma, contribute significantly to legal blindness globally.
- Congenital factors, including genetic disorders like retinitis pigmentosa, also play a crucial role in causing legal blindness.
- In some instances, the cause remains idiopathic, where the origin is unknown despite thorough investigation.
4. 🔬 Pathology and Consequences
4.1. Causes and Risk Factors of Legal Blindness
4.2. Consequences and Management of Legal Blindness
5. 🕵️ Clinical Manifestations
5.1. Vision Loss Symptoms
5.2. Circadian Rhythm Disorders
6. 🧪 Diagnosis and Treatment
- Diagnosis of legal blindness starts with a client's history and physical assessment, including visual acuity testing using the Snellen eye chart.
- Additional tests for blindness diagnosis include perimetry or visual field testing for peripheral vision, tonometry for intraocular pressure, dilated pupil fundus examination, fundoscopy, and color vision testing.
- Treatment of legal blindness focuses on addressing the underlying cause when possible.
- Routine comprehensive eye exams are crucial for monitoring clients with legal blindness.
- Low vision rehabilitation is recommended to help clients learn techniques to perform daily tasks despite visual acuity challenges.
- Assistive devices such as glasses, contact lenses, and magnification devices are often included in the treatment plan.
7. 🩹 Nursing Care Guidelines
- Maintain client safety and provide supportive care by understanding the extent of visual loss through medical record review.
- Ensure healthcare team members are notified of the client's visual impairment to tailor their interactions appropriately.
- Knock on the door, address the client by name, and introduce yourself and your role to establish a personal connection.
- Communicate directly, using normal volume and tone, and remain within the client's visual field if they have partial sight.
- Inquire about the client's usual methods for performing daily activities and offer assistance as needed to support independence.
- Explain procedures before touching the client to maintain comfort and trust.
- Orient the client to their environment by detailing the location of essential items like the bedside table, call light, and water.
- Keep necessary items and personal belongings within the client's reach to promote autonomy.
- Use the clock face method to describe food placement during meals to aid in orientation and independence.
- Maintain the bed in its lowest position to prevent falls and enhance safety.
8. 🏠 Patient and Family Education
- Implement fall precautions by using the sighted guide technique for safe ambulation: stand slightly in front and to the side, offer an elbow, walk at a comfortable pace, and describe the environment.
- Orient clients when seating them by placing their hands on the chair seat.
- Assess and address psychosocial needs such as anxiety and depression through discussions about feelings related to vision loss, using active listening.
- Ensure clients' comfort post-care by placing call lights within reach and informing them when leaving the room.
- Provide referrals for care coordination: include social workers, home healthcare, community resources, and adaptive equipment like audible watches and text-to-speech scanners.
- Educate clients and families on the treatment plan, prescriptions, low vision rehabilitation, and strategies for home safety and medication self-administration.
- Ensure clients have resources to manage chronic conditions, perform daily activities, and attend follow-up appointments.
- Expand on adaptive equipment examples: include talking clocks, large print reading materials, and magnifiers.
- List specific community resources: include local vision support groups and rehabilitation programs for those with low vision.