Abstract |
Ophthalmic pterygium represents a chronic, triangle-shaped, fibrovascular lesion, that expands
from the limbal stem cells towards the bulbar conjunctiva and the cornea. Its gradual expansion
may be sight-threatening. Pterygium development has been correlated to chronic UV exposure,
however, although pterygium has been extensively studied, its pathogenesis remains unclear.
In the past, it has been considered a degenerative disease, but recent studies, that identified
molecular genetic alterations, alterations in tumor suppression genes and presence of oncogenic
viruses, such as Human papillomavirus (HPV), in pterygia, indicated a possible neoplastic
nature of the disease.
HPV has been correlated with conjunctival papillomas and ocular surface squamous neoplasia
of the conjunctiva. Many studies have identified HPV in ophthalmic pterygia. However, there
is discordance regarding the prevalence of the virus in the different studies, that may be due
to geographical differences and variability in the virus identification methods.
In the present thesis, the evaluation of the use of swab samples, a minimally invasive diagnostic
technique for the identification of HPV, in 40 patients with ophthalmic pterygium, compared
with respective tissue specimens was studied. For the identification and genotyping of 14 high
and intermediate risk HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68) real
time PCR analysis was conducted. Moreover, 40 patients with normal conjunctiva were
included in our study as control group. Patients with no recurrence had an 1-year post-surgical
follow up.
The analysis of our results revealed the presence of HPV in 11 tissue specimens and in 9 swab
samples. The HPV subtypes detected were 33, 39, 45, 56, 59, 66, 68. The swab test had 81.82%
sensitivity and 100% specificity. Thirty-five patients with pterygium completed the 12-months
follow up. In 15 (43%) of them, pterygium removal was performed with bare sclera excision
and twenty patients underwent surgical excision with use of autologous conjunctival graft. The
analysis of the results revealed a correlation of the size of pterygium and the type of surgery
with disease relapse. Lastly, patients with disease recurrence had more probabilities to be
HPV+, whereas in HPV+ pterygium patients with no recurrence, the virus was not detected
one year after surgery. As for the patients with normal conjunctiva, the virus was not detected
in 37 of them, whereas in 3 patients the quantity of the sample was not adequate for analysis.
Our findings indicate that the use of swab samples and real time PCR analysis may be a
valuable tool for HPV detection in ophthalmic pterygium and may offer a better understanding
of its pathogenetic mechanism and recurrence.
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