Human Papillomavirus (HPV) is a common group of viruses known for causing infections of the skin and mucous membranes, particularly in the genital and oral areas. HPV has a marked tropism for squamous epithelium, the type of tissue found on the surface of the eye. While ocular infection is far less common than genital or oral infections, HPV can infect the ocular surface, leading to various growths and diseases.
Ocular Conditions Caused by Human Papillomavirus
The most common manifestation of HPV infection on the eye is the development of conjunctival papillomas, which are benign squamous cell tumors. These lesions typically result from infection with low-risk HPV types, primarily 6 and 11, which are also responsible for most genital warts. Conjunctival papillomas are fleshy, grayish-red masses that can appear on the tissue covering the white part of the eye or the inner lining of the eyelid.
These papillomas often present as either pedunculated (attached by a narrow stalk) or sessile (flatter and broadly based). They may appear exophytic (outward growing) and have a characteristic strawberry-like appearance. While most are harmless, they can cause irritation, a gritty feeling, and discomfort if they grow large enough to disrupt the natural tear film.
A more serious, though much rarer, outcome of ocular HPV infection is the development of Ocular Surface Squamous Neoplasia (OSSN). OSSN represents a spectrum of disease ranging from mild dysplasia to invasive squamous cell carcinoma of the conjunctiva and cornea. While HPV is not considered the sole cause of OSSN, it is implicated as a cofactor in a subset of cases, often alongside other risk factors like ultraviolet (UV) radiation and immunosuppression.
The high-risk HPV types, such as 16 and 18, are strongly associated with higher-grade lesions and are sometimes detected in OSSN tumors. HPV-related OSSN can present as a gelatinous, leukoplakic (whitish), or papillomatous mass, frequently located near the limbus, the border between the cornea and the conjunctiva.
How HPV Reaches the Eye
The transmission of HPV to the ocular surface differs significantly from its typical sexual route, relying instead on indirect methods of viral transfer. The most common mechanism in adults is known as autoinoculation, which involves the self-transfer of the virus from an infected area of the body, such as the genital or oral regions, to the eye. This process typically occurs when contaminated hands or fingers touch an existing HPV lesion and then rub the eye or eyelid.
In infants and children, the primary route of infection is vertical transmission, occurring when the baby passes through an HPV-infected birth canal. This can lead to juvenile-onset conjunctival papillomas, which may present as multiple, often pedunculated lesions. Although less common, the virus can also be transferred through contact with fomites, which are inanimate objects like shared towels or eye makeup contaminated with the virus.
The tear flow pattern on the eye also influences where the infection takes hold, with papillomas often localizing to the inferior and medial parts of the conjunctiva. This localization is related to tear drainage. Regardless of the initial transmission route, the virus gains access to the epithelial basal stem cells through microscopic abrasions on the eye’s surface.
Identifying and Managing Ocular HPV Infections
Identifying an ocular HPV infection begins with a thorough physical examination by an eye specialist, such as an ophthalmologist, who notes the characteristic appearance of the lesion. While the clinical presentation of a papilloma can be suggestive of HPV involvement, definitive diagnosis requires tissue analysis. A biopsy of the lesion is necessary for histopathological evaluation, which remains the gold standard for diagnosis, especially to rule out more aggressive conditions like OSSN.
Molecular testing, such as Polymerase Chain Reaction (PCR), is frequently utilized on the biopsied tissue to confirm the presence of viral DNA and identify the specific HPV genotype. Typing the strain is important because low-risk types (e.g., HPV 6 and 11) are associated with benign papillomas, while high-risk types (e.g., HPV 16) are linked to neoplastic changes. Non-invasive imaging techniques, such as Optical Coherence Tomography (OCT), are also used to characterize the lesions before treatment.
Management of conjunctival papillomas is determined by the size and location of the growth and the level of discomfort it causes. Small, non-bothersome growths may simply be monitored for changes. For larger or symptomatic lesions, the preferred treatment is often surgical excision, which may be combined with cryotherapy to destroy any residual cells at the base of the lesion.
Recurrence rates can be high due to the viral nature of the disease, making careful follow-up mandatory. Adjunctive medical treatments are often used to reduce this risk, including topical chemotherapy agents like Mitomycin C or 5-Fluorouracil. Immunomodulatory agents, such as topical interferon alpha-2b, are also effective, particularly for multiple or recurring lesions, as they suppress viral activity and proliferation.