Overview

Leprosy is a prolonged condition caused by the microorganisms. This infection is also known as Hansen’s disease.¹ The bacteria that cause leprosy are Mycobacterium leprae and Mycobacterium lepromatosis.¹ This infection affects the skin, eyes, peripheral nerves and pulmonary tissues. Leprosy can cause physical deformities. Eye involvement constitutes approximately 75% of cases in leprosy. It can lead to blindness. Dry eye syndrome is a salient characteristic of Hansen’s disease. There is a grading system by the WHO for the classification of disabilities involved in Hansen’s disease, especially for the eyes.² The disability caused to the eyes in leprosy can be cured in the majority of cases. Proper evaluation by an ophthalmologist is important to diagnose eye deformities in leprosy.

Pathophysiology

The pathophysiology of ocular leprosy involves direct invasion by Mycobacterium leprae and the cell-mediated immune system. Mycobacterium leprae can directly affect the tissues of the skin and the peripheral nerves, mainly in the lepromatous form of leprosy. Long-term close contact with an affected person can permit the bacteria to enter the body. The bacteria can reach the eyes through the adjacent affected skin or the lacrimal duct. Mycobacterium leprae has an affinity for cooler temperatures. The incubation period of the bacteria is long due to their slow cycle of replication. The cell-mediated immune response in tuberculoid leprosy is strong and affects only a few skin cells and nerves. The cell-mediated immune response in lepromatous leprosy is weak, and the skin and nerve tissues are damaged extensively. Bacterial load is high in this form.

Clinical features 

• Lagophthalmos (inability to close the eyelids)
• Corneal ulcers
• Ectropion (outward turning of the lid margin)
• Entropion (inward turning of lid margin)
• Trichiasis (inward misdirection of cilia)
• Corneal hypoesthesia
• Scleritis
• Uveitis
• Superficial punctate keratitis
• Episcleritis
• Glaucoma
• Cataract

Diagnosis

The diagnosis is primarily based on clinical features. The clinical signs of leprosy include erythematous patches with loss of sensation, thickened peripheral nerves, and the presence of bacilli in skin smears.³ Smears from the affected area of the skin are evaluated to identify the bacteria. Skin biopsy helps to detect the bacterial load and aids in the classification of bacteria. 

A nerve biopsy is also performed to aid in diagnosis.⁴ Lepromin test was used earlier to diagnose the disease. In cases where the eye is involved, corneal sensitivity testing is done. Lepra bacilli isolated from lacrimal fluid or conjunctival scraping are a diagnostic aid.

Management

Regular ophthalmic examination of people with Hansen’s disease to check the progression of the condition is the key to preventing and controlling the disease. The general and successful treatment modality of leprosy is multiple drug therapy. MDT treatment is effective against Mycobacterium leprae. It helps to control the infection. The drugs such as rifampicin, clofazimine, and dapsone regimens are found to be effective in treating multibacillary leprosy. For paucibacillary leprosy, the rifampicin, ofloxacin, and minocycline regimen is useful. Other management modalities include:

Ocular muscle exercises: Ocular muscle exercises enhance the strength of the ocular muscle fibres and increase blood circulation. Ocular muscle exercises help to get relief from muscle weakness and paralysis caused due to the infection.

Ocular lubrication: During the daytime, eye drops can be used, and during the night, eye ointment can be applied to hydrate the cornea.⁵

Corneal protection: Protective eyewear can be used during the daytime to prevent dehydration of the cornea. Sterile fabric or adhesive strips can be used to protect the cornea during nighttime.

Management of corneal ulcers: Corneal ulceration can be presented in the form of exposure keratopathy. The infection of the nasolacrimal duct can lead to corneal ulceration. Immediate intervention is critical in the management of corneal ulceration. For microbiological diagnosis, scrapings from the ulcer have to be obtained with precision. In cases of bacterial ulcers, topical broad-spectrum antibiotics along with non-steroidal anti-inflammatory drugs are administered.

Dacryocystectomy(DCT): This method manages infection and inflammation caused due to the blockage of the nasolacrimal duct.⁶

Scleritis and Uveitis management: Topical cycloplegics, topical steroids, oral and subconjunctival steroids, oral NSAIDs and anti-glaucoma medications are administered depending on the severity of the condition.⁷

Cataract and glaucoma management: Surgical removal of the cataractous lens is required in the management of cataracts. Oral or topical antiglaucoma medications are administered to manage early glaucoma. Advanced cases require trabeculectomy or shunt surgery.⁷

Lagophthalmos is managed by both medical and surgical interventions. The medical measures include administering artificial tears to improve the tear film, applying ointment during the daytime and night, taping of eyelids during the night for protection and using a moisture chamber glass to improve symptoms. The surgical measures include tarsorrhaphy, gold/platinum weight implantation, upper eyelid retraction and levator recession, and lower eyelid tightening and elevation. Severe lagophthalmos caused due to the paralysis of the facial nerve needs midface elevation.⁸

Prognosis and outcomes

Prognosis depends upon the early start of the treatment, the stage of the disease and adaptability to the therapy. Multidrug therapy helps in the rehabilitation of leprosy if administered at the initial phase of the disease. MDT can prevent distortion and neurological deformity to a greater extent. The reappearance of disease after treatment completion has been minimised after the introduction of MDT. Mild exposure keratopathy has a good prognosis. Severe cases can lead to corneal perforation and vision loss.

Summary

Leprosy is a prolonged condition caused by microorganisms such as Mycobacterium leprae. Leprosy is also known as Hansen’s disease. The skin, eyes, and nerves are the main affected areas in this infection. The pathophysiology includes direct invasion of Mycobacterium leprae, nerve damage, immune reaction and structural changes in the face and eyelids. The clinical features of ocular leprosy are characterised by lagophthalmos, corneal ulcer, madarosis, exposure keratopathy, neurotrophic keratitis, uveitis, scleritis, corneal anaesthesia, glaucoma and cataract.

The diagnosis is made mainly based on clinical symptoms and characteristic features. Skin biopsy from the affected area demonstrates bacterial load and the type of bacteria. Corneal sensitivity testing is done to diagnose ocular leprosy. The management of ocular leprosy includes the administration of multidrug therapy. Topical eye ointments, cycloplegic drugs, oral or topical corticosteroids and NSAIDs are used for the treatment of ocular leprosy. In severe cases, surgical intervention may be required. Regular ophthalmic examinations, early diagnosis and appropriate treatment are essential to control ocular complications. A proper follow-up after the completion of the treatment is needed to keep a check on the relapse of the disease.