Trachoma

Etiology

The causative agent of trachoma, the C trachomatis bacterium, is transmitted from infected to uninfected individuals through various means, including direct eye-to-eye spread during close contact, hand-eye contact, indirect transmission via contaminated objects (fomites), and transmission facilitated by eye-seeking flies.[14] Several factors, including crowded living arrangements, poor hygiene habits, and restricted access to sanitary facilities and clean water, contribute to the spread of trachoma.[15] These conditions create an environment conducive to the growth and persistence of C trachomatis bacteria within communities, continuing the infection cycle. Understanding the root causes of trachoma is crucial for developing targeted measures to stop the disease's spread, address ongoing infections, and mitigate its long-term impact.

C trachomatis can cause ocular infections such as trachoma and infections transmitted through sexual activity in humans.[16] Trachoma primarily affects the conjunctiva. The interaction between the life cycle of bacteria and the host's immune system plays a crucial role in the development of trachoma. Upon entering the eye, C trachomatis initiates the infection by entering the epithelial cells of the conjunctiva and undergoes a biphasic developmental cycle. The infectious form of the bacteria, known as the elementary bodies, initially binds to and penetrates the host cells.[17] Subsequently, once inside, they undergo differentiation into reticulate bodies, which multiply within the host cell's cytoplasm.[18]

The typical clinical signs of trachoma, such as conjunctival inflammation, follicular enlargement, and eventual scarring of the eyelids, are caused by the localized inflammatory response elicited by the replication of reticulate bodies.[19] The pathophysiology and regulation of trachoma are significantly influenced by the immunological response triggered by the infection. Although an effective immune response can facilitate the clearance of the infection, recurrent or persistent infections may lead to chronic inflammation and scarring, resulting in long-term complications such as trichiasis and blindness.[20]

Epidemiology

Trachoma ranks as the third leading cause of blindness globally, following cataracts and glaucoma.[21] According to estimates, nearly 8 million people are either blind or suffer from severe visual impairment due to trachoma.[22] The highest prevalence of the disease is observed in regions such as Africa, certain parts of the Middle East, the Indian subcontinent, Southeast Asia, and South America.[23] Studies conducted in June 2021 indicated that nearly 2 million individuals worldwide were on the brink of blindness due to trachoma, with an estimated 137 million people at risk of contracting the disease.[24] Epidemiological surveys conducted in 2023 revealed that around 116 million individuals globally resided in areas that warranted preventative measures for trachoma prevention and elimination. Furthermore, only 18 out of the known 62 trachoma-endemic countries had succeeded in eradicating the disease as a public health concern.[25][26]

Targeted public health measures have significantly reduced the prevalence of trachoma—a disease that was once widespread in many regions of the world. However, it remains a concern in certain areas, particularly in low- and middle-income countries with restricted access to hygienic and medical services. Various factors, including socioeconomic status, geographic location, and cultural practices, influence the epidemiology of trachoma.

Many countries in Africa are still in need of active preventative measures for trachoma.[27] In contrast, North America and Europe have experienced a significant reduction in disease prevalence primarily due to overall improvements in living standards rather than specific interventions.[14] Although the goal of eradicating trachoma worldwide by 2020 has not been achieved, hope remains with the implementation of treatment and prevention programs in endemic regions aiming to achieve the goal of disease elimination by 2030.[28]

Trachoma disproportionately affects women and children.[29] This gender disparity stems from women's increased exposure to contaminated water and unsanitary conditions, often due to their involvement with childcare and household duties.[30] Studies have shown that the odds ratio can be 1.8 to 4 times higher in females than males.[31]

Age is another significant factor influencing the occurrence of trachoma, with children aged 10 or younger bearing the largest burden. Due to their limited ability to practice basic hygiene and their close contact with infected individuals, young children are particularly susceptible to trachoma. During this age period, the prevalence of active trachoma typically peaks before declining during adolescence and adulthood.[32] On the other hand, individuals who experience untreated childhood infections are at risk of long-term complications such as blindness and trichiasis.

Although the prevalence of trachoma has significantly decreased in many parts of the world, it still poses a severe threat to public health in some areas, especially for marginalized groups of populations with little access to sanitary facilities and medical care. Implementing targeted interventions, including promoting facial cleanliness, improving hygiene and sanitation, ensuring access to clean drinking water, providing antibiotic treatment, and controlling fly populations in endemic areas, is crucial to preventing this pervasive and severe ocular disease and optimizing patient outcomes.

Pathophysiology

The pathophysiology of trachoma is characterized by the development of conjunctival scarring, which results from recurrent cycles of tissue repair and inflammation.[33] Extracellular matrix proteins such as collagen and fibronectin are deposited throughout the scarring process, leading to fibrosis and contraction of the conjunctival tissue.[33] Without treatment for this fibrotic scarring, complications such as eyelid entropion (inward turning of the eyelid) and trichiasis (misalignment of the lashes) may occur, potentially resulting in corneal abrasions, ulcerations, and eventual blindness.[34] Bacterial infection, inflammatory reactions, tissue remodeling, and host factors intricately interact in the pathophysiology of trachoma.[35] 

Trachoma is primarily associated with infections by serovars A, B, Ba, and C of the C trachomatis bacterium, while serovars D to K are typically linked to adult inclusion conjunctivitis. Other species within the Chlamydiaceae family, such as Chlamydophila psittaci and C pneumoniae, have also been implicated. Trachoma infection progresses through an initial 'active' inflammatory stage, which is more prevalent in preschool children. This stage may be mild and only result in trachomatous conjunctivitis (follicular or papillary), with the presence of papillary hypertrophy characterizing more severe cases.

Recurrent infection triggers a chronic immune response provoked by intermittent chlamydial antigens. This response manifests as a cell-mediated delayed hypersensitivity (type 4) response. The repeated insult from these antigens leads to scarring and other forms of permanent damage. This chronic "cicatricial" stage typically occurs in middle age, with most scarring concentrated on the upper tarsal plate. As this scar tissue contracts, it causes the in-turning of the lid, resulting in entropion, which eventually leads to trichiasis. Entropion is the most common cause of trichiasis in trachoma patients. However, in rare cases, trichiasis may also occur due to aberrant lashes or metaplastic lashes. Ultimately, blinding corneal opacification can develop as a result of these complications.

The obligate intracellular bacterium C trachomatis and the host's immune system interact intricately in the pathophysiology of trachoma, leading to conjunctival scarring, tissue destruction, and increasing inflammation.[36] During the early stages of infection, the conjunctival epithelial cells serve as the site of attachment and invasion for the elementary bodies of C trachomatis. Once inside the host cell, these elementary bodies transform into reticulate bodies, where they multiply within the infected cells' cytoplasm.[18][37] This intracellular multiplication triggers the infiltration of immune cells, such as neutrophils, macrophages, and lymphocytes, into the conjunctival tissue, eliciting an inflammatory response.

The inflammatory cascade triggered by C trachomatis infection releases proinflammatory cytokines and chemokines, which further amplify the immune response and contribute to tissue damage. Chronic inflammation on the conjunctival surface results in the formation of follicles, which are aggregations of lymphocytes, plasma cells, and epithelial cells. These follicles can potentially progress into papillary hypertrophy, characterized by the enlargement and hyperplasia of the conjunctival papillae.[38] Understanding these mechanisms is imperative for developing targeted interventions aimed at halting the progression of the disease and reducing the incidence of blindness caused by trachoma.

Histopathology

Active trachoma is commonly observed in children infected with C trachomatis. Classic findings include a hyperplastic conjunctival epithelium and widespread inflammatory infiltrates comprising B and T lymphocytes, neutrophils, macrophages, and plasma cells.[39] Staining for collagen subtypes reveals a generalized increase in collagen types 1, 3, and 4, along with the deposition of new type 5 fibers.[40] Conversely, adults with scarring exhibit an atrophic conjunctival epithelium and loss of goblet cells.[41] A thick scar consisting of type 5 collagen replaces the loose subepithelial stroma, with these newer fibers tightly adhering to the tarsal plate, leading to distortion. Conjunctival inflammation is often observed in these cases.

The normal conjunctiva undergoes histological and immunological alterations in active trachoma and trachomatous scarring.[38] Goblet cells, responsible for mucin secretion, are dispersed throughout the non-keratinized, stratified epithelium, which typically consists of 3 to 5 cell layers in a normal conjunctiva. This epithelium is covered by the tear film. Deeper within the lamina propria, connective tissue components such as lymphoid cells and blood arteries are present. Inflammation resulting from a C trachomatis infection is characterized by a mixed inflammatory cell infiltration and the presence of telangiectasia in capillaries and small venules.

Within the lamina propria, most of the mass and the core of lymphoid follicles comprise B cells. These follicles also contain T cells, macrophages, and additional B cells.[42] When large enough, lymphoid follicles can be observed in the everted tarsal conjunctivae, causing deformation of the overlaying epithelium. Goblet cells are reduced in the scarred conjunctiva, leading to a decrease in tear film volume and alterations in its composition. The lamina propria exhibits a scar that demonstrates increasingly disordered scarring. Scars may also affect the tarsal plate and extracellular matrix.

The chronic inflammation associated with trachoma progression leads to papillary hypertrophy, characterized by enlarged and hyperplastic conjunctival papillae.[43] These papillae contain increased inflammatory cells, such as lymphocytes and plasma cells, and are coated in a layer of squamous epithelium. Significant collagen deposition can be seen in severe cases, along with fibrosis, scarring, and disruption of normal tissue architecture in the conjunctiva.[44]

Follicular conjunctivitis, characterized by the formation of follicles within the conjunctival tissue, is one of the distinctive histological features of trachoma.[45] Typically, these follicles exhibit a central germinal center surrounded by a mantle of lymphocytes and epithelial cells. Histological examination of trachomatous follicles commonly reveals the presence of germinal centers, lymphocytic infiltration, and hypertrophy of the surrounding epithelium. Additionally, histopathological analysis of trachoma-affected tissues may reveal structural anomalies such as conjunctival scarring, fibrosis, metaplastic alterations, and inflammatory changes. Conjunctival scarring, marked by the replacement of normal tissue architecture with fibrous tissue, can lead to the rupture of the epithelial barrier and loss of goblet cells. Fibrotic alterations may result in complications such as entropion, trichiasis, and other eyelid abnormalities.[46]

Overall, histopathological examination of tissues affected by trachoma provides valuable insights into the underlying mechanisms of disease progression and the structural changes associated with chronic inflammation and scarring. This microscopic analysis helps guide clinical management and therapeutic interventions to prevent further tissue damage and preserve vision in affected individuals.

History and Physical

History

Patients with trachoma typically present with symptoms such as redness, itching, and irritation of the eyes and eyelids, along with eye discharge, eyelid swelling, eye pain, and sensitivity to light (photophobia). Assessing the duration of these symptoms is crucial. When gathering a patient's medical history, healthcare professionals should inquire about symptoms that could indicate trachoma and potential risk factors for the disease. Specifically, a history of travel to endemic regions, such as North Africa, the Middle East, and India, should be obtained. Additionally, if the patient is sexually active, concomitant vaginitis, cervicitis, or urethritis should be ruled out.

Physical Examination

Healthcare professionals should focus on identifying indications of trachoma in the eyes and surrounding structures.[19] Essential elements of the assessment are mentioned below.[47]

• Evaluation of conjunctival follicles: Trachoma often presents with tiny, raised nodules resembling follicles on the conjunctival surface. These follicles may be scattered widely or clustered in the inferior fornix of the eye.

• Examination of the conjunctiva and eyelids: Healthcare providers should check for symptoms of conjunctival inflammation, including redness, swelling, and discharge. They should also check the eyelids for signs of entropion, characterized by inward bending of the eyelid, or trichiasis, which can cause corneal abrasions and vision problems.  

• Visual acuity assessment: Healthcare providers should use standard testing tools, such as the Snellen chart or visual acuity cards, to identify any impairment in vision.

• Assessment of conjunctival scarring: Prolonged inflammation in trachoma patients may lead to conjunctival scarring, which is characterized by fibrotic bands, changes in tissue texture, and loss of normal architecture.

• Analysis of corneal integrity: Clinicians should examine the cornea for any signs of opacities, abrasions, or ulcerations. These conditions can result from persistent irritation caused by trichiasis or corneal exposure due to eyelid abnormalities.

• Evaluation of local lymph nodes and preauricular lymph nodes: A palpator can be used to feel any enlargements suggestive of chlamydial infection–related lymphadenopathy.

A comprehensive medical history and physical examination are crucial for the diagnostic evaluation of trachoma. Identifying distinctive indications and risk variables for the ailment can direct appropriate diagnostic tests and therapeutic interventions to prevent complications and preserve visual integrity in affected individuals. 

Active trachoma: This manifests as mixed follicular or papillary conjunctivitis, often associated with mucopurulent discharge. Active trachoma commonly presents with superior epithelial keratitis is commonly seen. Corneal vascularization may lead to the development of pannus.[48][49]

Cicatricial trachoma: This typically presents with stellate or linear conjunctival scars or broad confluent scars (known as Arlt line) in advanced stages. Although the entire conjunctiva is involved, the effects are more prominent on the upper tarsal plate. As follicles in this region resolve, a row of shallow depressions called Herbert pits [50] might be formed in the superior limbus. Trichiasis, distichiasis, corneal vascularization, and entropion can also manifest, often accompanied by severe corneal opacification. Destruction of goblet cells and the ductules of the lacrimal glands eventually leads to dry eyes.[10][51]

Evaluation

The diagnosis of trachoma primarily depends on the patient's history and clinical signs observed during a slit-lamp examination. Although several diagnostic tests have been developed to detect the organism, a universally recognized gold standard investigation does not exist.[52][53] Some of the tests currently used are listed below.

Laboratory Examinations

• Giemsa staining of smears of conjunctival cells to demonstrate the chlamydial inclusion body.

• Cell cultures and microscopy.

• Microbiological testing: This testing method often involves polymerase chain reaction and nucleic acid amplification tests, which are the 2 common molecular techniques used to confirm an active C trachomatis infection in laboratory settings. Conjunctival swabs or scrapings from affected individuals are collected and examined for the presence of C trachomatis DNA. While these methods are valuable for research purposes, they are often considered expensive and complex for routine clinical use.

• Serological testing: This testing method involves detecting antibodies against C trachomatis in serum samples using enzyme-linked immunosorbent assays (ELISAs) or immunofluorescence assays. However, serological testing is primarily utilized in epidemiological research rather than for clinical diagnosis.

Clinical Evaluation

• Trachoma severity grading: WHO has devised a streamlined grading system based on clinical indicators observed during the inspection to categorize the severity of trachoma. This system includes 5 categories—trachomatous trichiasis (TT), corneal opacity (CO), trachomatous inflammation follicular (TF), trachomatous inflammation intense (TI), and trachomatous scarring (TS).[54]

• Trichiasis assessment: This evaluation involves a direct flashlight examination, commonly utilized to identify ingrown eyelashes touching the cornea, which helps determine the presence and severity of trichiasis or eyelash misalignment. During this examination, the number and position of trichiatic eyelashes are recorded to assist in surgical planning.[47] 

 Radiography and Imaging Techniques

• Radiographic imaging: Radiographic imaging techniques, such as optical coherence tomography or ultrasonography, can be employed to assess structural abnormalities in the eye, particularly in cases of corneal opacity or scarring.

• Extra diagnostic testing: Conjunctival photography and mobile health technology serve as supplementary tools used in certain situations to record clinical observations, monitor and track the course of an illness, and assess treatment effectiveness. Modern techniques helpful for trachoma diagnosis include photography,[55] artificial machine learning approaches,[56] and automated deep learning methods.[57]

Treatment / Management

The SAFE strategy (surgery, antibiotics, facial cleanliness, and environmental improvement) recommended by WHO includes surgery for trichiasis, antibiotics, facial hygiene, and environmental improvement measures.[58]

• Antibiotics should be administered to the patient and all the family members.[59]
  • Azithromycin (20 mg/kg up to 1 g), as a single dose, stands out as the preferred antibiotic or treatment of choice, given its effectiveness and convenient dosing regimen, particularly when taken orally either as a single dose or as part of a mass drug administration approach.
  • Erythromycin (500 mg twice daily for 14 days) or doxycycline (100 mg twice daily for 10 days) may be considered, although caution is warranted with tetracyclines in pregnancy, breastfeeding, and among children.
  • Tetracycline ointment (1%) may be used topically. However, it is less effective than oral treatment.

• Facial cleanliness is important.[60]

• Environmental improvement includes proper sanitation, access to clean drinking water, control of flies, and other relevant measures.[61]
(B3)

• Surgical intervention may be necessary to address conditions such as entropion and trichiasis, ensuring functional and complete lid closure (see Image. Surgical Repair of Trachomatous Upper Eyelid Entropion).[62] 
(B2)

Management of Trichiasis and Cicatricial Entropion

Trachoma is the most common infectious cause of blindness globally, primarily due to conjunctival scarring leading to trichiasis and entropion, ultimately resulting in corneal scarring and eventual blindness. Therefore, effective management of trichiasis and cicatricial entropion in trachoma is imperative to prevent visual disability.[63][64]

Treatment of lashes: A movement to teach simple procedures to ancillary healthcare team members is necessary in areas where this disease is endemic. This will enable early intervention to prevent corneal injury and scarring.[65] 

• Simple epilation

• Destruction of eyelash follicles
  • Radiofrequency ablation of follicles
  • Cryotherapy to lash roots
  • Electrocautery
  • Laser (argon or other types) treatment of lash roots
  • Irradiation (infrequently used now)

• Surgical excision of roots of eyelashes

Surgical repair of trichiasis and entropion: The management of trichiasis and entropion in trachoma involves a range of surgical techniques to correct eyelid abnormalities and prevent corneal damage, as listed below.[66][67](A1)

• Tarsal rotation with bilamellar tarsal rotation or anterior lamellar tarsal rotation

• Tarsal repositioning with tarsal advancement with or without tarsal rotation

• Posterior lamellar lengthening with the advancement of the posterior lamella with or without an interpositional mucous membrane or tarsal graft

• Surgery to the anterior lamellar and eyelid margin
  • Anterior lamellar repositioning 
  • Eyelid margin split and eversion
  • Anterior tarsal wedge resection (or grooving) and eversion

• Tarsectomy

Differential Diagnosis

Distinguishing trachoma from other ocular disorders can be challenging due to overlapping clinical features. Therefore, it is crucial to carefully evaluate differential diagnoses to ensure appropriate management and avoid unnecessary treatment.[68] 

• Allergic conjunctivitis: The symptoms of allergic conjunctivitis can mimic the clinical signs of trachoma, including redness, itching, tearing, and swelling of the eyelids. Allergic conjunctivitis is usually bilateral and is often associated with prior exposure to allergens such as dust, pollen, or pet dander.

• Bacterial conjunctivitis: Acute bacterial conjunctivitis and trachoma share similar clinical manifestations, such as crusting on the eyelids, discharge, and redness. Bacterial conjunctivitis frequently manifests acutely, with symptoms appearing rapidly and resolving spontaneously. Trachoma, conversely, is characterized by recurrent infections and persistent inflammation typify trachoma (see Image. Bacterial Conjunctivitis).

• Viral conjunctivitis: Adenovirus or herpes simplex virus can induce viral conjunctivitis, exhibiting symptoms similar to trachoma, including photophobia, tearing, and redness. Nonetheless, systemic symptoms, such as fever and malaise, are commonly linked to viral conjunctivitis, which may aid in distinguishing it from trachoma.

• Dry eye syndrome: This condition shares symptoms with trachoma, including redness, ocular discomfort, and a sensation of foreign body presence. However, the hallmark of dry eye syndrome is inadequate tear production or instability of the tear film, leading to dryness and discomfort on the ocular surface.

• Pterygium and pinguecula: Pterygium and pinguecula are benign growths on the conjunctiva that resemble trachoma and can cause redness and irritation. These lesions are usually unilateral and situated next to the limbus, differentiating them from the diffuse conjunctival inflammation in trachoma. 

• Giant papillary conjunctivitis: This condition is an inflammatory conjunctivitis characterized by the production of giant papillae and is frequently linked to contact lens wear or ocular prostheses. Although it shares symptoms with trachoma, such as redness and itching, it typically presents bilaterally and has a history of ocular surface irritation.

• Atopic keratoconjunctivitis: This is a persistent inflammatory condition that affects the cornea and conjunctiva and is often linked to atopic dermatitis. Individuals suffering from atopic keratoconjunctivitis may exhibit signs of inflammation of the conjunctiva, including redness, itching, and photophobia, which can resemble those of trachoma. However, atopic keratoconjunctivitis typically presents bilaterally and can be linked to additional systemic atopic symptoms.

• Less common ocular conditions that can exhibit similar signs and symptoms to trachoma include chronic follicular conjunctivitis, Parinaud oculoglandular conjunctivitis, silent dacryocystitis, issues related to contact lens use, and various causes of entropion and trichiasis.

Staging

WHO recommends a simplified grading system for trachoma.[69] 

• Trachomatous inflammation, follicular (TF): This is characterized by the presence of five or more lymphoid follicles, each at least 0.5 mm in diameter, in the central region of the upper tarsal conjunctiva.

• Trachomatous inflammation, intense (TI): This manifests as significant inflammatory alterations in the conjunctiva, including pronounced thickening throughout the entire tarsal conjunctiva or marked thickening that obscures more than half of the typical deep tarsal vessels.

• Trachomatous scarring (TS): This is characterized by scarring of the tarsal conjunctiva, which presents as fine, white, horizontal lines parallel to the lid edge or linear lines. This scarring can lead to trichiasis (misaligned eyelashes) and deformities of the conjunctival surface, potentially causing corneal transparency issues.

• Trachomatous trichiasis (TT): This is defined as the presence of at least one eyelash touching the globe or evidence of recently removed inverted eyelashes. TT is associated with recurrent episodes of infection, inflammation, and scarring, leading to potential complications such as corneal abrasions and eyelid abnormalities.

• Corneal opacity (CO): This represents the most advanced stage of trachoma and is characterized by corneal opacification. If left untreated, this condition can lead to blindness and vision impairment.

Prognosis

The prognosis of trachoma is influenced by various factors, including disease stages, comorbidities such as trichiasis and corneal opacities, access to healthcare, and the implementation of therapy and prevention strategies. International efforts, such as adopting the SAFE approach, to contain and eradicate the disease have contributed to recent improvements in the prognosis of trachoma.

Several studies have shown significant reductions in the prevalence of active disease as a result of practicing this strategy.[70][71]

Early-stage trachoma: With prompt and adequate therapy, the prognosis is generally favorable for trachoma patients in their early stages (TF and TI). Antibiotics such as azithromycin and topical tetracycline effectively eliminate C trachomatis infections, reducing the risk of disease progression. Health education initiatives promoting facial cleanliness and environmental modifications are crucial in curtailing disease transmission and preventing reinfection within communities.

Advanced-stage trachoma: In advanced-stage trachoma with scarring (TS), the prognosis may worsen if complications like trichiasis and corneal opacities arise. Untreated trichiasis, characterized by misaligned eyelashes, can lead to corneal abrasions, ulcers, and blindness. However, surgical correction techniques such as posterior lamellar tarsal rotation or bilamellar tarsal rotation can significantly improve outcomes and prevent blindness.

Issues and the extended prognosis: Long-term prognosis in trachoma can be significantly influenced by complications like corneal opacities, neovascularization, and irreversible vision loss. If left untreated, corneal opacity and scarring resulting from recurring infections and persistent inflammation can cause blindness or visual impairment. Nonetheless, in extreme circumstances, some degree of vision restoration might be achievable with the appropriate medical and surgical procedures, including corneal transplantation.

Public health interventions and international initiatives: Efforts to manage and eradicate trachoma globally have led to a notable improvement in the disease's prognosis. Initiatives such as the International Trachoma Initiative (ITI) [72] and the WHO Alliance for the Global Elimination of Trachoma by 2020 have contributed to significant reductions in trachoma prevalence and blindness worldwide.[73][74] Through mass drug administration campaigns, surgical outreach initiatives, and community-based treatments, patient outcomes have been enhanced, and access to care has improved.[75]

Although trachoma remains a significant public health concern, particularly in resource-limited regions, advancements in diagnosis, prevention, and treatment have led to improved prognoses and outcomes for affected individuals. However, achieving global trachoma elimination and preventing unnecessary blindness requires sustained funding for trachoma control programs, research endeavors, and advocacy initiatives.[76]

Complications

Undiagnosed or improperly managed trachoma can cause several issues that can eventually lead to blindness and permanent vision impairment.[77] Recurring infections, persistent inflammation, and disease-related tissue scarring frequently bring on these adverse effects. Some of the main complications associated with trachoma are listed below.

• Trichiasis: Trichiasis refers to the misalignment of lashes, leading to repetitive abrasion of the corneal surface with each blink. Over time, this irritation can cause corneal abrasions, ulcerations, and scarring from misdirected eyelashes that irritate and rub the cornea. Without proper treatment, trichiasis can progress to corneal opacities and eventual blindness.

• Entropion: Entropion occurs when the eyelid turns inward, causing the lashes to scrape on the eye's surface, resulting in discomfort, corneal abrasions, and potential blindness if left untreated. Entropion is a consequence of advanced trachoma in which the eyelids compress inward due to scarring and recurrent infections.

• Distichiasis: This condition occurs when an additional row of lashes grows along the eyelid's edge, pointing toward the direction of the eye. These unusual eyelashes can cause pain, redness, and even corneal injury by irritating the cornea. Severe trachoma-related eyelid deformities and scarring can lead to this condition.

• Dry eye syndrome: This syndrome can be triggered by the detrimental impact of trachoma on the cornea and conjunctiva, diminishing tear production and compromising tear film integrity. Symptoms include redness, burning, itching, and impaired vision. Chronic dryness also elevates the risk of eye infections and other complications.

• Superadded bacterial infection: The chronic inflammation and scarring associated with trachoma can compromise the eye's immune system, heightening susceptibility to secondary bacterial infections. If left untreated, these infections can exacerbate trachoma symptoms, leading to conditions like conjunctivitis, corneal ulcers, and potentially blindness. Effective management often necessitates antibiotic therapy.

• Corneal opacities: Usually a consequence of trachoma, corneal opacities result from prolonged inflammation and scarring of the cornea. These opacities may cause reduced visual acuity and possibly irreversible vision loss by interfering with light's ability to enter the eye. Dense corneal opacities can obstruct the pupil and cause central vision impairments in severe situations.

• Corneal neovascularization: Corneal neovascularization, a complication of trachoma, involves the chronic inflammation and vascularization of the cornea. This abnormal blood vessel growth can disrupt the eye's natural optical properties, leading to compromised corneal transparency and potentially resulting in visual impairment.

• Conjunctival scarring: Recurrent episodes of inflammation in trachoma may cause conjunctival scarring, characterized by fibrosis and alteration of the architecture and texture of the surrounding tissue. This scarring on the conjunctiva may worsen ocular surface dryness, destabilize the tear film, and increase the risk of corneal problems and subsequent infections.

• Blindness: Trachoma, if left untreated or inadequately managed, can lead to irreversible blindness, particularly in cases of severe trichiasis,  corneal opacities, or other issues impacting visual function. Blindness caused by trachoma not only affects individuals but also has profound socioeconomic repercussions on their communities, significantly impacting their quality of life.