Introduction:
The cornea of the eye is the outermost layer of the eye. It is a transparent part of the eyes. In a normal eye, the cornea is susceptible to light. Although aqueous humor (fluid of the eye) nourishes the eye and tears protect the eyes. Various infectious and inflammatory diseases can cause cornea scarring, leading to severe vision loss and blindness.
What Are the Causes of Corneal Blindness?
The following are the causes of corneal blindness:
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Certain Infections and Ulcerations: Various microbial infections such as bacterial, fungal, or viral keratitis of the cornea can cause corneal blindness. A leading cause of blindness is trachoma, an eye infection. It causes corneal scarring that results in blindness. In addition, some rare diseases like onchocerciasis and leprosy can also result in blindness.
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Bacterial Keratitis: It is the most common type of infectious keratitis. The bacteria causing bacterial keratitis are staphylococci, streptococci, pseudomonas aeruginosa, and enterobacter species.
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Fungal Keratitis: Various fungi cause fungal keratitis that results in blindness. The most common fungi are candida, aspergillus, and fusarium.
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Herpes Simplex Keratitis (HSK): Herpes simplex virus infection can also cause blindness due to corneal involvement. Recurrent illness can cause opacification of the cornea and visual loss.
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Trachoma: Globally, trachoma is the leading cause of blindness caused by Chlamydia trachomatis bacterial infection through sexual contact.
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Dry Eye Disease: It is also known as keratoconjunctivitis sicca. It includes the triad, including joint pain, dry mouth, and keratoconjunctivitis sicca. In addition, it causes further worsening of conditions causing discomfort and, in the end, causing blindness.
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Keratoconus: Keratoconus causes thinning of the cornea, resulting in reduced visual acuity and blindness.
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Deficiency of Specific Nutrition and Malnutrition: Vitamin A deficiency is an important reason for blindness in childhood.
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Trauma to Eyes: Direct trauma to the eye and corneal ulcerations ultimately result in corneal blindness.
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Some Congenital Diseases: Congenital disorders (born blind), or corneal infections and ulcerations in early infancy can be a reason for corneal blindness.
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Corneal Disorders: Disorders like Fuchs’ Endothelial Dystrophy and other corneal degenerations can also cause vision loss.
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Issues in Lifestyle: Use of several ayurvedic drops, kajal, and Surma, causes more harm than good, resulting in vision loss. Using honey and ginger juice for eye drops can cause severe damage to the eyes.
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Non-infectious Neonatorum: It is an autoimmune disease. It is a leading reason for blindness.
What Are the Symptoms Associated With Corneal Blindness?
Initially, the patient may feel severe pain, blurred vision, tearing, redness in the eyes, extreme sensitivity to light, and discharge from the eye. The disease progresses, leading to the formation of corneal opacity, loss of corneal transparency, erosion, and ultimately causes blindness.
How to Diagnose Corneal Blindness?
For a proper treatment of infectious keratitis, the first step is to collect the sample for culture, and then direct microscopy is helpful to see various strains. After that, the gold standard is gram staining and culture methods (growing microorganisms on culture plates) that provide results instantaneously. PCR (polymerase chain reaction) does confirmation.
What Is the Definitive Treatment for Corneal Blindness?
Corneal transplantation or corneal graft is the definitive treatment for corneal blindness. In the procedure, a part of the cornea or the entire cornea is replaced by a donated healthy cornea.
Improving awareness about eye diseases can help reduce corneal blindness and promote timely interventions.
Corneal Transplantation:
Organ donation is the current treatment modality used for corneal blindness. Initially, anterior corneal opacities were treated using lamellar keratoplasty. Next, it is used in the treatment of keratoconus.
Types of lamellar keratoplasty are anterior lamellar keratoplasty (ALK), superficial anterior lamellar keratoplasty (SALK), automated lamellar therapeutic keratoplasty (ALTK), and others.
Various treatment options for infectious keratitis that can cause corneal blindness include the following:
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Fungal Keratitis: Antifungal agents reduce the treatment duration for completely eradicating the causative agent. Topical Natamycin is the choice of drug, and sometimes Amphotericin B. Patients who do not respond to medical treatment require surgical procedures for correction.
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Bacterial Keratitis: Topical antibiotics are used for treatment. Fluoroquinolones are commonly used. Even anti-collagenases and steroids can be used for the treatment.
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Dry Eye Disease: Schirmer's test detected reduced tear production. The severity of disease can be reduced by avoiding prolonged exposure to digital devices, staying in a dry atmosphere, and using external protection like contact lenses or glasses.
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Keratoconus: The early detection of keratoconus is more essential than monitoring the progression of the disease and doing required interventions at the time, which can improve the patient's condition. The additive keratoplasty helps in increasing the thickness of the cornea.
What Are the Recent Advancements in the Treatment of Corneal Blindness?
Recent advancements in treatment modalities include the following procedures:
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Intraoperative Optical Coherence Tomography (IOCT): Intraoperative surgery continuous feedback is provided by the IOCT.
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Femtosecond Laser-Assisted Lamellar Keratoplasty (FALK): A laser is used for total thickness penetrating keratoplasty (PKP). It gives more improvements when compared to the manual one.
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Bioengineered Cornea: Bioengineered cornea replaces the part of the cornea without the help of a donor. The bioengineered cornea can help in restoring sight in patients who are blind or visually impaired. The most recent advancement is tissue-engineered hydrogels.
How to Prevent Corneal Blindness?
Various public health awareness programs can help increase people's awareness of eye disease, which can help in early diagnosis and reduce further complications. Vitamin A supplements are given as preventive measures. Onchocerciasis can cause blindness and can be prevented by ivermectin distribution in public. Traumatic corneal abrasion can cause blindness due to the involvement of the cornea. Prophylactic antibiotics help prevent blindness due to trauma. Use sunglasses to reduce exposure to harsh conditions by use of eye drops, hats, and external protection.
Conclusion
Corneal blindness mainly occurs when the cornea is damaged and affected. It is the leading cause of blindness among the population. It can be due to trauma, disease, or underlying infections. It causes progressive loss of vision. Therefore, early diagnosis and treatment help prevent permanent eye damage. In addition, adapting preventive measures such as nutritional supplements and eye protection can prevent and reduce further damage.
