Types of Blindness: Questions and Answers

Understanding the different types of blindness is crucial. From various symptoms of blindness to the different kinds of blindness, we will answer the most popular questions. We’ll navigate through different types of blind conditions. The encouraging news is that treatment approaches are continually evolving, becoming more effective. Advancements in medical science offer hope for individuals grappling with different forms of blindness. 

What Is Blindness?

Blindness is a visual impairment characterized by the complete absence or severe reduction of vision, resulting in an inability to see and perceive visual stimuli. It can be caused by various factors, including eye diseases, injuries, genetic conditions, or systemic health issues affecting the visual system. Blindness can manifest in different degrees, ranging from partial visual impairment to total loss of vision. People who are blind often rely on other senses and adaptive techniques to navigate and interact with their environment. The impact of blindness extends beyond the physical aspect, influencing daily activities, independence, and overall quality of life. Rehabilitation, assistive technologies, and support services play crucial roles in helping individuals with blindness lead fulfilling lives.

Normal vision is denoted by a visual acuity of 1.0; reduced vision falls in the range of 0.9–0.2; low vision corresponds to 0.1–0.04, and total blindness is indicated by 0.03–0. Having 3% vision is categorized as mild blindness, yet this does not diminish the gravity of the prognosis.

Ophthalmology conventionally recognizes the following degrees of blindness:

• Practical blindness, where the patient can perceive light or retains residual vision up to 3%.
• Absolute blindness, referred to as amaurosis.

For individuals grappling with significant visual impairment, a comprehensive diagnostic approach is undertaken. Treatment modalities, contingent on the specific pathology, may involve conservative, surgical, or a combination of approaches. All patients experiencing persistent blindness in both eyes necessitate specialized rehabilitation and external assistance.

Causes of blindness

The causes of blindness are determined by the type of visual impairment.

Light Perception Disorders

Symptomatic hemeralopia (day blindness) can result from the following conditions:

• Retinal pathology, including pigmentary dystrophy, inflammatory diseases, and retinal detachment;
• Optic nerve pathology, involving atrophy, stasis processes, and inflammatory damage;
• Severe myopia without adequate correction.

Symptomatic hemeralopia is the outcome of irreversible changes in the retinal membrane and optic nerve, disrupting rod and cone neurons. Impaired night vision may also occur in the early stages of glaucoma development. Liver pathologies, particularly cirrhosis, affect dark adaptation, compromising vitamin A resynthesis.

Functional hemeralopia arises due to nutritional deficiencies and a general vitamin deficit, especially a shortage of retinol, necessary for synthesizing visual pigment.

Absolute blindness or critical visual impairment, affecting both light and color perception, may result from various pathological processes:

• Myopic disease, where excessive stretching of the eye’s membranes leads to blindness, causing retinal and optic disc dystrophy;
• Blindness in diabetes, with retinopathy developing initially, leading to bleeding, retinal detachment, and dystrophic damage to the optic nerve;
• Hypertensive blindness, associated with persistent high blood pressure in vessels supplying the retina and optic nerve;
• Congenital and acquired cataracts, where significant lens opacity hinders light flow, preventing it from reaching the retina (complete vision restoration is possible after lens replacement);
• Profound prematurity (before 30-32 weeks), when the visual organ hasn’t fully developed during intrauterine life (extraterrestrial conditions cannot be identical to in utero, affecting the maturation of the visual organ after premature birth);
• Blindness in stroke, where the area of impaired blood flow in the brain affects the visual center or pathways, leading to central (cortical) blindness;
• Corneal pathology, responsible for about 40% of blindness cases worldwide (keratitis, corneal ulcer, corneal clouding);
• Uveitis, an inflammatory vascular tract eye disease, accounting for about 10% of blindness causes;
• Traumatic eye injuries, including penetrating and blunt (contusion) injuries, as well as irreversible post-traumatic changes;
• Glaucoma, a chronic increase in intraocular pressure gradually leading to atrophy of the optic nerve disc;
• Acute retinal vessel disorders, accounting for about 3% of blindness cases, with internal retinal structures highly sensitive to oxygen deficiency (cessation or rapid weakening of blood flow over 1-1.5 hours leads to the “functional death” of the retina);
• Retinal and optic nerve diseases, encompassing primary and secondary retinal dystrophies, retinal detachment, retinitis, age-related macular degeneration.

Age-related macular degeneration (AMD) is often found not only in old age but also in young people (juvenile AMD). The disease is considered an initial form of atherosclerosis when systemic vascular disorders are still absent. Some scientists believe that the pathology is associated with the inheritance of specific genes that trigger earlier cell death compared to normal eye physiology. Timely AMD diagnosis allows preserving vision and initiating targeted treatment promptly. Blindness in this condition occurs due to the growth of inadequate vessels in the pathological focus, leading to retinal detachment.

Types of Vision Impairment

Blindness comes in various forms, with classification methods taking into account different characteristics.

Hemeralopia, or day blindness, is characterized by impaired twilight vision, named after the fact that diurnal birds struggle to see in the dark. Hemeralopia is categorized as:

• Symptomatic, indicating a manifestation of ophthalmological or systemic diseases.
• Functional, representing a temporary condition that resolves after addressing vitamin deficiencies.
• Congenital, where fundus changes are absent, and the causes remain unclear, often showing a familial hereditary pattern.

Daltonism, known as color hereditary blindness, results from a genetic disruption in the synthesis of visual pigments. This condition often involves difficulties in perceiving the red and green spectrum.

Complete or near-complete loss of visual functions affects both light and color perception.

Psychogenic blindness, a transient state, constitutes a distinct category. Triggered by a powerful psychotraumatic factor, the visual analyzer may temporarily cease its function.

Symptoms of Blindness 

The predominant indication of blindness is a notable reduction in vision. This reduction can manifest as if there’s a veil or dense fog obstructing the view, spots interfering with the field of vision, or a significant narrowing or loss of a portion of the visual field. A distinct symptom is color anomaly, where individuals may struggle to perceive one or several colors. In severe cases of achromatopsia, the world appears in black and white tones as individuals can only distinguish shades within the gray spectrum.

In cases of night blindness, vision diminishes specifically in low-light conditions. Under good lighting, individuals may not face challenges in observing both distant and nearby objects. However, during darker hours, they find it challenging to discern the outlines of surrounding objects and experience poor spatial orientation. Hemeralopia often has a hereditary origin, linked to genetically induced damage to retinal cells. The acquired form is associated with diseases affecting the retinal and vascular membranes of the eye, optic nerve damage, and a deficiency of vitamin A in the body.

How Can You Go Blind?

• Aging: Age-related changes in the retina and macular degeneration contribute significantly to visual impairment and blindness among older individuals.
• Head Injuries: Prior damage to the occipital lobe and other injuries that may result in increased intracranial pressure are considered risk factors.
• Inflammatory Conditions: Encephalitis, meningitis, and inflammatory brain diseases can induce blindness when affecting the occipital lobes.
• Eye Injuries: Contusions, helminthiasis (parasitic eye infections, e.g., nematode infections) are associated with a sudden decline in vision, with uncertain recovery.
• Occupational Hazards: Exposure to hazardous occupational activities poses a risk of vision impairment.
• Stroke: Previous strokes, especially in the vertebrobasilar basin, impacting blood supply to the occipital lobes, with potential but not guaranteed recovery.
• Abnormal Blood Sugar Levels: Unstable, decompensated, or incompletely compensated diabetes mellitus poses a risk of vision loss within 10 to 20 years.
• Medication and Alcohol Use: Certain drugs, medications, and alcoholism, especially exposure to methyl alcohol, can affect the optic nerve. Individual examination is crucial to understand specific causes.

Vision Simulators

Numerous online vision simulators are available to offer a glimpse into the visual experiences of blind people, fostering greater understanding and empathy. These simulators attempt to replicate various visual impairments, allowing individuals with normal vision to temporarily experience the challenges faced by those who are blind or visually impaired. Exploring such simulators can enhance awareness and empathy, promoting a more inclusive and compassionate perspective towards individuals living with blindness. For more information, check our guide on vision simulator technology.

Treatment

The strategy for addressing blindness varies depending on its underlying causes. Restoring lost vision due to cataract clouding often involves surgical procedures, specifically cataract phacoemulsification followed by the implantation of an intraocular lens. In instances of retinal detachment, surgery is a common intervention, but its efficacy is closely tied to the duration of the condition.

In cases of inflammatory processes within the eye or acute vascular disorders, a conservative therapeutic approach is typically adopted. This may necessitate hospitalization, and medications may be administered directly into the periocular area or under the conjunctiva.

Managing hereditary diseases, degenerative processes in the retina, or optic nerve dystrophy poses significant challenges. In such situations, pharmaceutical therapy is usually supportive, aiming to slow down the pathological process and retain any remaining vision.

Congenital color anomalies generally do not demand active treatment. However, for improved quality of life, colored lenses and specially framed glasses compensating for color perception deficiencies can be considered. Additionally, individuals with low vision or preserved residual vision may benefit from the use of specialized optical correction aids.

Navigating the Complex Spectrum of Blindness and Vision Impairment

In conclusion, understanding the diverse array of blind symptoms and different types of blindness is crucial in curing vision impairment diseases. From various types of vision impairment to the intricacies of blind eyes, the awareness of symptoms of blindness plays a pivotal role in early detection and intervention. Exploring the types of vision impairment sheds light on the multifaceted nature of visual challenges and emphasizes the importance of proactive measures. As we delve into how one can go blind, it becomes evident that knowledge and preventive measures are paramount. In this journey toward visual well-being, recognizing symptoms, understanding different types of blindness, and staying informed about potential causes are essential steps. By doing so, we contribute to creating a more supportive and inclusive environment for those navigating the complexities of visual impairment.