Detection of herpes simplex virus and human papilloma virus in ophthalmic pterygium

Risk factors for pterygium: Latest research progress on major pathogenesis

A pterygium is a wedge-shaped fibrovascular growth of the conjunctiva membrane that extends onto the cornea, which is the outer layer of the eye. It is also known as surfer's eye. Growth of a pterygium can also occur on the either side of the eye, attaching firmly to the sclera. Pterygia are one of the world's most common ocular diseases. However, the pathogenesis remains unsolved to date. As the pathogenesis of pterygium is closely related to finding the ideal treatment, a clear understanding of the pathogenesis will lead to better treatment and lower the recurrence rate, which is notably high and more difficult to treat than a primary pterygium. Massive studies have recently been conducted to determine the exact causes and mechanism of pterygia. We evaluated the pathogenetic factors ultraviolet radiation, viral infection, tumor suppressor genes p53, growth factors, oxidative stress, apoptosis and neuropeptides in the progression of the disease. The heightened expression of TRPV1 suggests its potential contribution in the occurrence of pterygium, promoting its inflammation and modulating sensory responses in ocular tissues. Subsequently, the developmental mechanism of pterygium, along with its correlation with dry eye disease is proposed to facilitate the identification of pathogenetic factors for pterygia, contributing to the advancement of understanding in this area and may lead to improved surgical outcomes.

Risk Factors for Recurrence in the Treatment of Recurrent Pterygium

PURPOSE

The aim of this study was to identify the postoperative recurrence rate of recurrent pterygium and to evaluate risk factors for the recurrence.

METHODS

This study was a retrospective interventional nonrandomized consecutive case series. In this single-center study, 119 eyes of patients with recurrent pterygium who underwent surgery with a follow-up period of >12 months after the surgery were analyzed. The clinical characteristics of pterygium were classified according to the length of corneal involvement and Tan grade. The main outcome was the recurrence rate. The secondary outcome was the risk factors for recurrence.

RESULTS

The mean follow-up period was 42 ± 28.6 months. Recurrence was observed in 15 patients (12.6%). The average postoperative recurrence period was 7.7 ± 6.7 months. Twelve patients experienced a recurrence within 12 months. Eyes with recurrence had a significantly greater length of corneal involvement (2.47 ± 0.72 mm) and number of previous surgery (1.9 ± 1.3) than those without (1.97 ± 0.74 mm, and 1.3 ± 0.7, both P = 0.04). Multivariate analysis showed that recurrence was significantly associated with the length of corneal involvement (odds ratio [OR] 2.38, 95% confidence interval [CI], 1.02-5.57, P = 0.05) and the number of previous surgeries (OR: 1.91, 95% CI, 1.03-3.58, P = 0.04) but not with sex (OR: 3.71, 95% CI, 0.90-15.2, P = 0.07), age (OR: 0.99, 95% CI, 0.94-1.04, P = 0.59), and use of mitomycin C (OR: 0.31, 95% CI, 0.07-1.21, P = 0.09).

CONCLUSIONS

The postoperative recurrence rate of recurrent pterygium was 12.6%. The preoperative length of corneal involvement and number of previous pterygium surgeries were significantly correlated with recurrence. Male sex and nonuse of mitomycin C tended to correlate with recurrence.

Human papilloma virus presence and its physical status in primary pterygium

Pterygium is one of the most frequent pathologies in ophthalmology, and is a benign, overgrowth of fibrovascular tissue, often with a wing-like appearance, from the conjunctiva over the cornea. It is composed of an epithelium and highly vascular, sub-epithelial, loose connective tissue. There is much debate surround the pathogenesis of pterygium and a number of theories have been put forward including genetic instability, cellular proliferation, inflammatory influence, and degeneration of connective tissue, angiogenesis, aberrant apoptosis and viral infection. At present, the involvement of human papillomavirus (HPV) in the genesis of pterygium is controversial, as have reported that HPV is present in 58% of cases, while others have failed to detect HPV in pterygium. In this study, we evaluated the presence and viral genotype of HPV DNA in pterygia and healthy conjunctiva sample, and virus integration into the cellular genome. Forty primary pterygia samples and 12 healthy conjunctiva samples were analyzed to HPV DNA presence by polymerase chain reaction, using MY09/MY11 primers of HPV-L1 gene. Viral genotype was identified by DNA sequence analysis of this amplicon. HPV integration into the cellular genome was analyzed by western blot detecting HPV-L1 capsid protein. Presence of HPV was observed in 19 of the 40 pterygia samples. In contrast, healthy conjunctiva samples were negative. To determine virus type, sequence analyses were performed. Interestingly, 11 out of the 19-pterygium samples were identified as HPV-11 type, meanwhile, the remaining 8 pterygium samples were identified as HPV-18. HPV-L1 capsid protein were found only in 3 out of the 10 samples studied. In conclusion, our study identified the presence of HPV DNA exclusively in pterygium samples and described HPV-11 and -18 genotypes. Our results suggest that HPV may be involved in the pathogenesis of pterygium. On the other hand, the expression of the L1-HPV protein suggests viral integration into the cellular genome.

The Role of the Stromal Extracellular Matrix in the Development of Pterygium Pathology: An Update

Pterygium is a benign fibrovascular lesion of the bulbar conjunctiva with frequent involvement of the corneal limbus. Its pathogenesis has been mainly attributed to sun exposure to ultraviolet-B radiation. Obtained evidence has shown that it is a complex and multifactorial process which involves multiple mechanisms such as oxidative stress, dysregulation of cell cycle checkpoints, induction of inflammatory mediators and growth factors, angiogenic stimulation, extracellular matrix (ECM) disorders, and, most likely, viruses and hereditary changes. In this review, we aim to collect all authors’ experiences and our own, with respect to the study of fibroelastic ECM of pterygium. Collagen and elastin are intrinsic indicators of physiological and pathological states. Here, we focus on an in-depth analysis of collagen (types I and III), as well as the main constituents of elastic fibers (tropoelastin (TE), fibrillins (FBNs), and fibulins (FBLNs)) and the enzymes (lysyl oxidases (LOXs)) that carry out their assembly or crosslinking. All the studies established that changes in the fibroelastic ECM occur in pterygium, based on the following facts: An increase in the synthesis and deposition of an immature form of collagen type III, which showed the process of tissue remodeling. An increase in protein levels in most of the constituents necessary for the development of elastic fibers, except FBLN4, whose biological roles are critical in the binding of the enzyme LOX, as well as FBN1 for the development of stable elastin. There was gene overexpression of TE, FBN1, FBLN5, and LOXL1, while the expression of LOX and FBLN2 and -4 remained stable. In conclusion, collagen and elastin, as well as several constituents involved in elastic fiber assembly are overexpressed in human pterygium, thus, supporting the hypothesis that there is dysregulation in the synthesis and crosslinking of the fibroelastic component, constituting an important pathogenetic mechanism for the development of the disease.

Evaluation of Primary Pterygia on Basis of the Loss of Vertical Length of Plica Semilunaris

Purpose

To propose a new grading system for primary pterygia based on the morphological loss of vertical length of plica semilunaris (LPS).

Methods

We included 50 eyes from 41 patients with primary pterygium. LPS was defined and quantified as the ratio of the length of loss of the normal vertical morphology at plica semilunaris to the vertical corneal diameter using anterior-segment photographs. Grades of tear metalloproteinase 9 (MMP-9) expression by point-of-care immunoassay, which is a well-known biomarker for inflammation, was correlated with the extent of LPS (%) of pterygia. Then, LPS was paralleled with the pre-established grading systems on the basis of tissue translucency (i.e., T grade) and vascularity (i.e., V grade) of the pterygium body.

Results

MMP-9 grades was 2.39 ± 1.12 in the group with LPS ≥50% and was 1.56 ± 1.12 in the group with LPS <50% (P = 0.016). In a linear regression, the extent of LPS was positively correlated with MMP-9 grades (r = 0.315, P = 0.026). MMP-9 expression did not differ between T grades or V grades. The extents of LPS were well correlated positively with both T grades (r = 0.495 and P < 0.001) and V grades (r = 0.344 and P = 0.015).

Conclusions

We devised a new grading system using LPS on the basis of morphological loss of the normal vertical plica semilunaris in primary pterygia. The extent of LPS correlated well with T grades and V grades and also reflected the expression of MMP-9 in tears.

Translational Relevance

The new clinical LPS grading system reflects severity and MMP-9 expression in tears in primary pterygia.

Pterygium: an update on pathophysiology, clinical features, and management

Pterygium is a relatively common ocular surface disease. The clinical aspects and the treatment options have been studied since many years ago, but many uncertainties still exist. The core pathologic pathway and the role of heredity in the development of pterygium are still attractive fields for the researchers. The role of pterygium in corneal irregularities, in addition to the refractive properties of pterygium removal, has been increasingly recognized through numerous studies. The association between pterygium and ocular surface neoplasia is challenging the traditional beliefs regarding the safe profile of the disease. The need for a comprehensive clinical classification system has encouraged homogenization of trials and prediction of the recurrence rate of the pterygium following surgical removal. Evolving surgical methods have been associated with some complications, whose diagnosis and management are necessary for ophthalmic surgeons. According to the review, the main risk factor of pterygium progression remains to be the ultraviolet exposure. A major part of the clinical evaluation should consist of differentiating between typical and atypical pterygia, where the latter may be associated with the risk of ocular surface neoplasia. The effect of pterygium on astigmatism and the aberrations of the cornea may evoke the need for an early removal with a purpose of reducing secondary refractive error. Among the surgical methods, conjunctival or conjunctival-limbal autografting seems to be the first choice for ophthalmic surgeons because the recurrence rate following the procedure has been reported to be lower, compared with other procedures. The use of adjuvant options is supported in the literature, where intraoperative and postoperative mitomycin C has been the adjuvant treatment of choice. The efficacy and safety of anti–vascular endothelial growth factor agents and cyclosporine have been postulated; however, their exact role in the treatment of the pterygium requires further studies.

Prevalence of Human Papillomavirus Genotypes in Pterygia from Thai Individuals

Purpose: Pterygium, a common ocular growth, has an unknown pathogenesis and aetiology. Environmental factors such as ultraviolet light, genetic factors and viral infections may be implicated in the development of pterygia. Human papillomavirus (HPV), an oncogenic virus, has previous been detected in individuals with pterygia. The aim of this study was to assess the prevalence of HPV genotypes in pterygia from Thai individuals.Methods: DNA was extracted from 389 pterygia. HPV was detected by nested PCR and HPV genotyping was conducted using reverse hybridization. The DNA sequences of HPV-L1 genes were analyzed.Results: HPV was detected in only 6.8% (25/389) of pterygia from Thai individuals. The majority (16/25, 64%) of strains were genotyped as HPV-16 and the remainder (9/25, 36%) could not be typed. Four pterygia showed evidence of coinfection by HPV-16 and either HPV-18 (2/25, 8%) or HPV-58 (2/25, 8%). Nine of 11 samples showed the same HPV-16 L1 gene sequence that was identical to a HPV-16 reference sequence in GenBank. The remaining two samples each bore silent single nucleotide mutations (T1078G and T1081A) that did not result in amino acid changes.Conclusion: HPV, especially HPV-16, may be one of the pathogens causing pterygia in Thai individuals. Genotyping data suggested that HPV-16 from pterygia may be similar in sequence to HPV-16 causing cervical cancer.

Changes of Corneal Biomechanical Properties upon Exclusive Ytt-/Sr-90 Irradiation of Pterygium

BACKGROUND

It is known that pterygia above a certain size cause astigmatism and other aberrations of the human cornea and thus impair the quality of vision. Exclusive Sr-/Ytt-90 beta irradiation is a highly effective treatment for primary pterygia. The aim of this retrospective study is to determine the extent to which higher order corneal aberrations are affected by this treatment.

METHODS

Evaluation of corneal topographies and wavefront aberration data of 20 primary pterygia patients generated before and at different points in time in the first year after irradiation. Additionally, the size of the pterygium was measured.

RESULTS

The study showed a significant increase in coma and triple leaf aberrations in pterygia with a horizontal length of 2 mm and more. It was also found that a pterygium size greater than 2 mm significantly induces astigmatism. Both phenomena reduce visual quality. In none of the patients could a pterygium recurrence be detected after irradiation.

CONCLUSIONS

If the pterygium size is less than 2 mm, early exclusive Sr/Ytt-90 beta irradiation can be recommended. If the size is more than 2 mm, a pterygium excision 6 months after beta irradiation can be discussed.

Pterygium Is Related to Short Axial Length

PURPOSE

To test the hypothesis that pterygium presents with both refractive and anatomical changes, especially short axial length.

METHODS

A retrospective, hospital-based cross-sectional study included 521 eyes from 521 patients who were enrolled through a community survey by Shanghai Heping Eye Hospital was conducted. Patients with primary pterygium in at least 1 eye were considered the pterygium group, and those with normal eyes were considered the nonpterygium group. The prevalence and length of pterygium, refractive characteristics including spherical power, astigmatism, corneal curvature, and anatomical parameters including axial length, anterior chamber depth, endothelial cell density, and corneal thickness were compared between groups.

RESULTS

Five hundred twenty-one eyes of 521 patients (214 men and 307 women) with a mean age of 70.5 ± 7.6 years were included in the study. The prevalence of hyperopia (81.6%, 65.1%, P = 0.001), axial length (23.1 ± 1.2 mm, 24.2 ± 2.4 mm, P < 0.001), anterior chamber depth (2.9 ± 0.3 cm, 3.1 ± 0.4 cm, P = 0.001), flat K value (42.94 ± 2.16 diopters, 43.73 ± 1.48 diopters, P = 0.002), Kmax (51.13 ± 7.74 diopters, 47.49 ± 5.62 diopters, P < 0.001), and spherical power (0.97 ± 2.40 diopters, -0.82 ± 4.40 diopters, P < 0.001) were statistically different between the pterygium and nonpterygium groups. Age (r = -0.21, P = 0.025), corneal astigmatism (r = -0.41, P < 0.001), flat K value (r = -0.39, P < 0.001), and endothelial cell density (r = -0.33, P = 0.001) were all negatively correlated with the length of pterygium. The prevalence of pterygium and severe pterygium over 3 mm were statistically different according to the severity of hyperopia (P < 0.001) and axial length (P < 0.001). Stratified χ analysis showed that axial length, rather than hyperopia, was a related factor to pterygium (odds ratio = 5.23, 95% confidence interval: 2.50-10.93).

CONCLUSIONS

We conclude from our study that the prevalence of pterygium is related to small eye size. SDF-1/CXCR4 signaling may play a vital role in pterygium and shorter axial length. Further study focused on SDF-1/CXCR4 signaling will be needed.

Interferon Alpha-2b Eye Drops Prevent Recurrence of Pterygium After the Bare Sclera Technique: A Single-Center, Sequential, and Controlled Study

To investigate the efficacy and safety of interferon (IFN) alpha-2b eye drops in preventing pterygium recurrence after the bare sclera technique.

Ocular Human Papillomavirus Infections

CONTEXT

- Human papillomavirus (HPV) has a well-known role in the pathogenesis of squamous cell carcinoma and precursor lesions of the cervix, anogenital region, and head and neck, but its role in the development of squamous neoplasms of the eye, particularly the conjunctiva, remains unclear.

OBJECTIVE

- To review recent evidence implicating HPV in the pathophysiology of ocular lesions.

DATA SOURCES

- Published articles obtained from a PubMed search of the English literature were the primary sources for this review.

CONCLUSIONS

- The low-risk HPV types 6 and 11 appear to play a role in the development of at least a subset of conjunctival squamous papillomas. The role of HPV in the pathogenesis of pterygium and ocular surface squamous neoplasia is less well defined. There is evidence to suggest that HPV may be a cofactor in the development of these lesions, acting in concert with ultraviolet radiation and/or human immunodeficiency virus infection in a subgroup of cases.

Human papillomavirus infection and ocular surface disease (Review)

Human papillomavirus (HPV) infection has been implicated as a primary cause of lesions in the anogenital region, skin, oropharynx and respiratory tract. Additionally, the role of HPV in the pathogenesis of ocular surface disease has also been extensively studied. Conjunctival papilloma development has been strongly associated with the HPV infection of certain subtypes. On the other hand, the role of HPV in conjunctival pterygium, conjunctival intraepithelial neoplasia (CIN) and ocular surface squamous neoplasia (OSSN) remains controversial. Genetic predisposition and environmental factor is important in HPV hosts as regards the pathogenesis of ocular surface disease. Several studies have indicate a synergic role of HPV with ultraviolet radiation in pterygium establishment. A higher recurrence risk rate and more aggressive disease of ophthalmic pterygium is observed in cases of HPV infection. The purpose of this review was to provide a systematic review of the literature and to assist in a better understanding of the role of HPV in ocular surface disease.

[Pterygium: etiology, pathogenesis, treatment]

Pterygium is a degenerative condition characterized by fibrovascular outgrowth of conjunctiva over the cornea. Many theories exist that try to explain its pathogenesis. The current belief is that this disease is multifactorial with ultraviolet radiation being the most important trigger. Attention is also paid to such factors as tear film changes, cytokines and growth factors disbalance, immunologic disturbances, genetic mutations, and viral infections. Modern classifications consider the rate of fibrovascular growth, its progressive potential, and histological features. In the beginning pterygium is usually asymptomatic, however, dry eye manifestations may be present, such as burning, itching, and/or tearing. As the lesion grows toward the optical zone, visual acuity gets compromised, and thus, surgical treatment is required. Because of recurrences and repeated surgeries, the growth of the lesion may become more aggressive and cause irregular astigmatism. Comprehensive surgery of pterygium is aimed at not only removing the lesion, but also preventing recurrences. Advisable are modified bare sclera techniques with subsequent transposition of the conjunctival flap, conjunctival autotransplantation, amniotic membrane transplantation, and peripheral lamellar keratoplasty (in cases of significant ingrowth). In some cases, antirecurrent adjuvant therapy may be considered that involves the use of mitomycin C, 5-fluoruracil, and VEGF inhibitors. However, the search for the best treatment for pterygium, i.e. an easy to perform, cosmetically-friendly method associated with minimal risk of recurrences and/or complications, remains an interest of modern ophthalmology.

Do Demodex mites play a role in pterygium development?

Numerous reports point to Demodex mites as the aetiology of certain eye and skin conditions, hence it is highly probable that infestation with these mites may also play a role in the aetiology and pathogenesis of pterygium. Therefore here we present a hypothesis: whether the presence of Demodex mites in eyelash hair follicles significantly correlates with the presence of pterygia, which could point to a potential role of these mites in the development of such lesions. We present preliminary data for supporting this hypothesis. These results were collected from a group of 69 subjects, including 39 with pterygium. Subjects were studied for the presence of Demodex folliculorum and/or D. brevis within eyelash follicles. The sample was defined as positive if at least one parasite, larva or egg were present. Preliminary statistical analyses were performed, and indicated a significant relationship between Demodex mite infestation and the presence of pterygium (p<0.05). This suggests that demodicosis could be one of the factors causing pterygium and significantly contribute to its development. Subjects who had both pterygium and Demodex infestation formed a dominant group. The proportion of subjects with both pterygia and Demodex presence is high at 93.33%, while the proportion of subjects without pterygia who have mites is low at 20.51%. Aforementioned results support our working hypothesis that infestation with Demodex mites may result in pterygium development and therefore patients diagnosed with pterygium should be assessed for the presence of Demodex to verify our preliminary results. In the present paper, we discuss potential influence of Demodex on conjunctiva and propose a hypothetical pathological mechanism linking the development of pterygia with demodicosis.

The role of ultraviolet radiation in the pathogenesis of pterygia (Review)

Pterygium is a common ophthalmic disease affecting humans only. Extensive epidemiological data have demonstrated a causative effect of chronic ultraviolet (UV) radiation on pterygia. Progress has been made in determining the origin of pterygia, their nasal predilection and wing‑shaped appearance, and the roles of UV radiation in the initiation and the development of pterygia. In the present review, the current understanding of the involvement of UV radiation in the pathogenesis of pterygia is summarized. This involvement includes the alteration of limbal stem cells and fibroblasts that contribute to the initiation of pterygia and the induction of various pro‑inflammatory cytokines, growth factors and matrix metalloproteinases that promote the progression of pterygia. Further elucidation of the roles of UV radiation in the pathogenesis of pterygia may help to encourage individuals at risk of developing pterygia to take preventive measures and aid researchers in the development of novel targeted therapeutic agents to treat pterygia.

Identification of human papillomavirus in pterygium

PURPOSE

The purpose of this study was to evaluate the involvement of human papillomavirus in the pathogenesis of primary and recurrent pterygium in northern Israel.

METHODS

A retrospective study examined 100 randomly chosen pterygium specimens with solar elastosis, from 100 patients who underwent pterygium surgery during 2012-2013 at the Emek Medical Center. All the specimens were analysed for evidence of human papillomavirus infection by immunohistochemistry.

RESULTS

Human papillomavirus was not detected in any of the 100 pterygia samples by immunohistochemistry. These used samples were taken from 100 patients with mean age of 51.5 years and a primary: recurrent ratio of 8.09:1.

CONCLUSION

We conclude from our study that human papillomavirus infection does not appear to be an important pathogenic factor of pterygium in Israel.

Pterygium concomitant with other ocular surface lesions: Clinical implications and pathogenetic links

In the present study, we aimed to evaluate the co-existence of ophthalmic pterygium with other ocular surface lesions in a cohort of patients from the Cretan population. This is a retrospective evaluation of all pterygia in patients examined and treated at the Department of Ophthalmology of the University Hospital of Heraklion, Greece during an 8-year period (from June 2006 to June 2014). A total of 158 cases was examined. Ocular surface images and medical history were evaluated in order to detect concomitant ocular surface pathological conditions. Concomitant lesions included conjunctival nevi (5 cases, 3.16%), iris nevi (4 cases, 2.53%), conjunctival papillomas (8 cases, 5.06%), conjunctival intraepithelial neoplasia (CIN; 4 cases, 2.53%) and 6 cases of hypertophy of the plica semilunaris (3.79%). Of note, pterygium was overlying the iris which was occupied by the iris nevus in 2 out of the 4 cases of iris nevus. Overall, our data indicate that ophthalmic pterygium may often co-exist with other clinically significant ocular surface lesions. The association of ophthalmic pterygium with conjunctival papillomas or CIN stresses the potential involvement of human papilloma virus in the pathogenesis of ophthalmic pterygium, whereas the topographical association of pterygium with iris nevus may offer support to the transcameral light pathway pathogenetic mechanism.

human adenoviruses role in ophthalmic pterygium formation

Background:

Ophthalmic pterygium is a common benign lesion of unknown origin and the pathogenesis might be vision-threatening. This problem is often associated with exposure to solar light. Recent evidence suggests that potentially oncogenic viruses such as human papillomavirus and Epstein-Barr virus may be involved in the pathogenesis of pterygia. Expression of specific adenovirus genes such as E1A and E1B, which potentially have many functions, may contribute to their oncogenic activity as well as relevance to cellular immortalization.

Objectives:

For the first time, we aimed to investigate involvement of adenoviruses in pterygium formation.

Patients and Methods:

Fifty tissue specimens of pterygium from patients undergoing pterygium surgery (as cases), 50 conjunctival swab samples from the same patients and 10 conjunctival biopsy specimens from individuals without pterygium such as patients undergoing cataract surgery (as controls) were analyzed for evidence of adenovirus infection with polymerase chain reaction using specific primers chosen from the moderately conserved region of the hexon gene. Furthermore, β-globin primers were used to access the quality of extracted DNA. Data was analyzed using SPSS (version 16) software.

Results:

Of 50 patients, 20 were men and 30 women with mean age of 61.1 ± 16.9 years ranged between 22 and 85 years. All samples of pterygia had positive results for adenoviruses DNA with polymerase chain reaction, but none of the negative control groups displayed adenoviruses. The pterygium group and the control groups were β-globin positive. Direct sequencing of PCR products confirmed Adenovirus infection.

Conclusions:

Adenoviruses might act as a possible cause of pterygium formation and other factors could play a synergistic role in the development. However, further larger studies are required to confirm this hypothesis.

Auto-avulsion and resolution of corneal pterygium

PURPOSE

Corneal pterygium is a frequently encountered ocular condition in clinical practice. The lesion presents as a fibrous, winged-like growth that typically manifests on the nasal aspect of the conjunctiva and cornea. Pterygia can be surgically removed by excision when they cause significant discomfort, visual impairment, or poor cosmesis. However, the recurrence rate after excision remains high without adjunctive therapy. We present an exceedingly rare case of resolution of a pterygium by auto-avulsion followed by subsequent recurrence of the lesion.

CASE REPORT

A 63-year-old Asian man presented to the clinic with pain and foreign body sensation. Anterior segment evaluation revealed a large corneal epithelial defect with an adjacent area of loose conjunctival tissue. Ocular history included a pterygium in the same area of the defect. Subsequent follow-up revealed a regrowth of the pterygium at the exact location.

CONCLUSIONS

Strong tension imposed on the cornea by a pterygium could result in auto-avulsion of the lesion. The resulting corneal defect can then be treated accordingly. Recurrent pterygium is possible without adjunctive therapy, such as those seen with bare sclera excision.

Immunohistochemical localization of D-β-aspartic acid-containing proteins in pterygium

Biologically uncommon D-β-aspartic acid (D-β-Asp) residues have been reported to accumulate in organs affected by age-related disorders. In the present study, we investigated the localization of D-β-Asp-containing proteins in cases of pterygium, one of the most prominent age-related ocular conditions. Immunohistochemical localization of D-β-Asp-containing proteins was investigated in surgical specimens of pterygium from 20 patients and control specimens from 10 patients. Strong immunoreactivity to D-β-Asp-containing proteins was observed in subepithelial elastotic lesions and surrounding collagenous lesions from all surgical specimens with pterygia. In contrast, no immunoreactivity to D-β-Asp-containing proteins was seen in pterygium-free specimens. D-β-Asp-containing proteins are produced in organs as they are affected by the aging process. In addition, conversion of L- to D-aspartyl residues is accelerated by ultraviolet (UV) irradiation. Since pterygia can form due to aging or UV exposure, it is reasonable to find D-β-Asp-containing proteins in specimens with pterygia. Furthermore, since D-β-Asp is a non-native amino acid, D-β-Asp-containing proteins may be recognized as allogeneic antigens. Therefore, D-β-Asp-containing proteins in pterygia may responsible for the fibrovascular changes seen in the disorder.

Oxidant/antioxidant state in tissue of prymary and recurrent pterygium

BACKGROUND

Pterygium is a disorder of the ocular surface induced by chronic exposure to UV-light. Abundant data is available from patients with primary pterygium, but scarce from those with recurrent pterygium. The present study aimed to explore the oxidant/antioxidant status in tissue of primary and recurrent pterigium in men and women.

METHODS

Pathological tissue samples were taken during surgery on patients with primary and recurrent pterygium. Healthy conjunctive tissue samples were taken during cataract surgery. After homogenization of 77 tissue samples, evaluation was made of thiobarbituric reactive substances (TBARS), nitric oxide (NO), total antioxidant status (TAS) and the activity of the three main antioxidant enzymes: glutathione peroxidase, superoxide dismutase and catalase. Gender differences were evaluated.

RESULTS

Compared to the control group, in the primary pterygium group there was an increase in NO and TAS, and a tendency to a decrease of all antioxidant enzymes, indicating an increase in non-enzymatic antioxidant activity. Compared to the control group, in the recurrent pterygium group there was a significant decrease in the level of TAS and antioxidant enzymes. A high positive correlation was found between most of measured parameters within the control group and the recurrent pterygium group, but not within the primary pterygium group. Compared to men, a significant difference was observed in the elevated NO level and low TAS level of women in the prymary pterygium group.

CONCLUSIONS

The diminished antioxidant defense in the recurrent pterygium group, possibly determined mainly by decreased non-enzymatic activity, supports the idea that oxidative stress plays an important role in the recurrence of this disorder.

Prevalence and viral load of oncogenic human papillomavirus (HPV) in pterygia in multi-ethnic patients in the Malay Peninsula

PURPOSE

The aim of the study was to determine the prevalence of human papillomavirus (HPV) in primary and recurrent pterygia samples collected from different ethnic groups in the equatorial Malay Peninsula.

METHODS

DNA was extracted from 45 specimens of freshly obtained primary and recurrent pterygia from patients and from 11 normal conjunctival swabs from volunteers with no ocular surface lesion as control. The presence of HPV DNA was detected by nested PCR. PCR-positive samples were subjected to DNA sequencing to determine the HPV genotypes. Real-time PCR with HPV16 and HPV18 type-specific TaqMan probes was employed to determine the viral DNA copy number.

RESULTS

Of 45 pterygia samples with acceptable DNA quality, 29 (64.4%) were positive for HPV DNA, whereas all the normal conjunctiva swabs were HPV negative. Type 18 was the most prevalent (41.4% of positive samples) genotype followed by type 16 (27.6%). There was one case each of the less common HPV58 and HPV59. Seven of the samples harboured mixed infections of both HPV16 and HPV18. All the four known recurrent pterygia samples were HPV-positive, whereas the sole early-stage pterygium sample in the study was HPV-negative. There was no significant association between HPV-positive status with gender or age. A high proportion of patients from the Indian ethnic group (five of six) were HPV-positive, whereas the Malay patients were found to have higher HPV positivity than the Chinese. The viral load of HPV18 samples ranged between 2 × 10(2) and 3 × 10(4) copies per μg, whereas the viral load of HPV16 specimen was 4 × 10(1) to 10(2) copies per μg.

CONCLUSION

This report describes for the first time the quantitative measurement of HPV viral DNA for pterygium samples. The high prevalence of oncogenic HPVs in our samples suggests a possible role for HPV in the pathogenesis of pterygia. Moreover, the relatively low HPV viral load is concordant with the premalignant nature of this ocular condition.

Progress in the pathogenesis of pterygium

Pterygium is a type of benign uncontrolled growth of the conjunctive tissue that lays over the sclera. It can significantly alter visual function in advanced cases and become inflamed, leading to redness and irritation in the area. Although the exact etiology of pterygium remains uncertain, recent advances have provided important insight into the pathogenesis of pterygium. These studies indicate that tumor suppressor gene p53 and other genes associated with DNA repair, cell proliferation, migration and angiogenesis are critical for the development of pterygium. In addition, Human papillomavirus infection has been shown to be a risk factor in some populations. In this article, the current understanding of the pathogenesis of pterygium is reviewed.

Viral involvement in the pathogenesis and clinical features of ophthalmic pterygium (Review)

Pterygium is a potentially vision-threatening fibrovascular lesion originating from the conjunctiva that often extends on the corneal surface. Although it has been extensively studied, its pathogenesis has yet to be fully elucidated. Recent evidence on molecular genetic abnormalities in pterygium suggested neoplastic changes of limbal stem cells potentially associated with exposure to ultraviolet (UV) light. Human papillomavirus (HPV) is an oncogenic virus, associated with squamo-proliferative lesions of the anogenital region, skin and oropharynx. Several studies have shown HPV involvement in the pathogenesis of conjunctival neoplastic lesions, including papilloma and squamous cell carcinoma. The involvement of HPV as a co-factor in the pathogenesis of pterygium, although suggested by several studies using PCR and immunohistochemical techniques, remains controversial. Moreover, a marked variation in the prevalence of HPV in ophthalmic pterygium has been reported by different studies. Ethnic susceptibility and methodological differences in the detection of HPV may account for this variation. Surgical excision, often using sophisticated techniques, is the standard current method of therapy for pterygium. However, recurrences are frequent and recurrent lesions tend to be more aggressive. If indeed HPV is involved in pterygium pathogenesis or recurrence, anti-viral medications or vaccination may be new options in pterygium therapy.

Prevalence and clinicopathologic findings of conjunctival epithelial neoplasia in pterygia

PURPOSE

To study the prevalence of conjunctival neoplasia in clinically diagnosed pterygia and the clinicopathologic characteristics of conjunctival tissues obtained from pterygium excision.

DESIGN

Prospective, observational case series.

PARTICIPANTS

From February through August 2007, consecutive subjects indicated for pterygium excision were enrolled from an outpatient eye clinic of King Chulalongkorn Memorial Hospital, Bangkok, Thailand, and from the eye camp at the 6th Station of the Thai Red Cross Society, Aranyaprathet District, Sa Kaeo, Thailand. A total of 498 eyes from 482 subjects were studied. The mean age of the subjects was 56.5 ± 11.7 years. The male-to-female ratio was 3:7.

METHODS

Clinical data were gathered, including age, sex, occupation, family history, and medical history. Pterygia were clinically graded as mild, intermediate, or fleshy. Tissues from surgical fields were fixed in formalin and processed using standard pathology laboratory methods.

MAIN OUTCOME MEASURES

Histopathologic results were examined in a masked fashion by 3 pathologists.

RESULTS

Ninety-one percent of tissue was from primary pterygia. Most lesions were classified as intermediate grade (45.2%). Histopathologic results showed that 4 eyes had conjunctival intraepithelial neoplasia. Two eyes had minimal cellular atypia at the conjunctival epithelium. Two eyes had complex choristoma. For the subjects who had conjunctival epithelial neoplasia, the mean age was 57.0 ± 8.0 years, 44.4% were male, and none had a history of carcinoma in other organs or any history of herpes virus, human papilloma virus, or human immunodeficiency virus infections.

CONCLUSIONS

The prevalence of conjunctival epithelial neoplasia in clinically diagnosed pterygia is approximately 1.8%. Because the clinical characteristics of subjects who have conjunctival epithelial neoplasia apparently did not differ from those without, tissue pathologic examination may be required to diagnose the condition.

Immunohistochemical detection of Hsp90 and Ki-67 in pterygium

BACKGROUND

To examine the immunohistochemical expression of heat shock protein 90 (Hsp90) and Ki-67 protein in human pterygium.

MATERIALS AND METHODS

Tissues obtained during pterygium surgery of 15 patients who underwent the bare-sclera procedure and 10 normal conjunctivae were studied. All of these pterygia were primary ones. Recurrent pterygia were excluded. Normal bulbar conjunctivas (2 x 2 mm) were obtained from the nasal region close to the limbus from patients during their cataract and retina surgeries. Immunohistochemical detection of Hsp90 and Ki67 was done using the streptavidin-biotin method in paraffin embedded tissue sections.

RESULTS

The percentage of cells stained for Hsp90 was greater for pterygium epithelium (76 ± 10.8) than for normal conjunctiva (1.4 ± 0.8). In each pterygium sample more than 60% of cells were positive. The differences in positive cells between normal and pterygium epithelium were highly significant for Hsp90 (P < 0,001).Pterygium epithelium also showed a higher percentage of cells that stained for Ki67 (10.1 ± 9.5) than for normal conjunctiva (2.1 ± 1.9). The differences in positive cells were also statistically significant for Ki67 (P < 0.01). Although there were significant differences in the majority of samples observed. It was noted that in some samples there was no difference between normal and pterygium epithelium for Ki67.

CONCLUSION

Our results indicate an abnormal expression of Hsp90 and ki-67 in pterygium samples when compared to normal conjunctiva.The finding of abnormal expression of levels of Hsp90 in pterygium samples can stimulate new research into pterygium and its recurrence.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1128478792898812.

Association of human papilloma virus with pterygia and ocular-surface squamous neoplasia

There are more microorganisms that colonize the human body than resident cells; some are commensal whereas others are pathogenic. Pathogenic microorganisms are sensed by the innate or adaptive immune system, an immune response is initiated, and the infection is often cleared. Some microorganisms have developed strategies to evade immune defenses, ensuring their long-term survival with potentially devastating consequences for the host. Approximately 18% of all cancers can be attributed to infective agents; the most common being Helicobacter pylori, Human papilloma virus (HPV) and Hepatitis B and C virus in causing stomach, cervical and liver carcinoma, respectively. This review focuses on whether HPV infection is necessary for initiating pterygia, a common benign condition and ocular-surface squamous neoplasia (OSSN), a rare disease with metastatic potential. The search engine PubMed was used to identify articles from the literature related to HPV and pterygium or conjunctival neoplasia. From 34 investigations that studied HPV in pterygia and OSSN, a prevalence rate of 18.6% (136/731) and 33.8% (144/426), respectively, was recorded. The variation in HPV prevalence (0-100%) for both disease groups may have arisen from study-design faults and the techniques used to identify the virus. Overall, the data suggest that HPV is not necessary for initiating either condition but may be a co-factor in susceptible hosts. Currently, over 60 million people worldwide have been immunized with HPV vaccines, but any effect on pterygium and OSSN development may not be known for some time as these lesions can evolve over decades or occur in older individuals.

Presence of human papillomavirus in pterygium in Taiwan

PURPOSE

To evaluate the prevalence and possible role of human papillomavirus (HPV) in the formation of pterygia in patients in Taiwan, a tropical country with high prevalence of pterygium.

METHODS

A total of 62 patients with 65 pterygia were retrospectively examined. Ten normal conjunctiva, 8 conjunctival nevi, and 2 malignant conjunctival melanomas served as controls. HPV detection and typing were accomplished using polymerase chain reaction amplification of the viral sequences. HPV-positive specimens underwent further investigation with fluorescence in situ hybridization. Clinical histories were recorded for each patient.

RESULTS

Based on polymerase chain reaction analysis, 2 of 65 pterygia harbored HPV type 18, and they were also fluorescence in situ hybridization positive. No conjunctival control had HPV. There was no statistically significant correlation between pterygium and the presence of HPV. The presence of HPV was not significantly different between primary and recurrent pterygia.

CONCLUSIONS

The limited presence of HPV DNA in pterygium does not conclude that HPV is necessary or acting alone in the formation of pterygium, but HPV may still be implicated to play a role in some pterygia in Taiwan.

[Comparative analysis of histopathological and clinical characteristics of pterygium]

BACKGROUND/AIM

Pterygium internum presents a significant epidemiological problem. Its etiopathogenesis is still unclear. After surgical removal it shows great tendency to recidives. The aim of this paper was to investigate connection between histopathological characteristics (inflammation presence, vascularization degree and fibrinoid changes) of pterygium and its clinical characteristics (duration, size, pterygium grade, presence of Fuchs' spots and recidives) and determine indicators for recidives prediction.

METHODS

We analyzed the material taken from 55 patients operated by Arlthi's method. The samples were colored by using standard histochemical methods: hematoxylin-eosin (HE), trichrome Masson painting, Gomora reticulin and PAS technique.

RESULTS

Pterygium was mostly covered by epithelium resembling conjunctival, while in the frontal cap region it showed the morphology of plate-layer cornea epithelium. The structural basis of the epithelium was composed of continuous basal lamina and continuous adhesive fibres underneath. This adhesive basis showed fibrinoid changes in the form of oval islands of various size, parallel to convexity of pterygium, or in the form of unified focus. The number, caliber and type of blood vessels showed a pronounced variability. Duration of pterygium and its size were in negative correlation with intensity of inflammation, without statistical significance. Pterygium with a longer period of develepment had negative correlation with the degree of vascularization (p > 0.05). The presence of Fuchs' spots showed a statitistically significant positive correlation with the degree of vascularization (p < 0.05). The intensity of fibrinoid changes was higher in pterygium with Fuchs' spots and in those which recurred (p > 0.05).

CONCLUSION

Histopathological analysis of pterygium morphological shapes is a good basis for the prediction of recidives, which present the greatest problem in the treatment of this widely spread disease.

Successful Surgical Intervention for Childhood Pterygium Using a Conjunctival Autograft

Childhood pterygia are extremely rare and no consensus currently exists regarding surgical management in cases of significant symptomatology. The authors describe a case of a childhood pterygium in a 9-year-old boy successfully treated with a superior conjunctival autograft. At 6 months of follow-up, no signs of recurrence were detected and the patient reported marked improvement in symptoms. Use of this technique may be beneficial in certain cases of childhood pterygia.

Occurrence of human papillomavirus in pterygia

PURPOSE

The aim of the study was to assess the occurrence of human papillomavirus (HPV) DNA in pterygium.

METHODS

The study involved 89 patients undergoing surgical procedures at the Department of Ophthalmology, Medical University of Lublin, Poland. Group 1 included 58 patients with clinically diagnosed pterygium. Group 2 consisted of 31 individuals with normal conjunctiva. The material was collected during elective surgical procedures. The presence of HPV genome was determined using polymerase chain reaction (PCR). Once the presence of HPV DNA was confirmed, 28 HPV genotypes were determined using reverse hybridization.

RESULTS

The determinations confirmed the presence of HPV DNA in pterygium. In the material collected from 58 cases of pterygium (group 1), HPV DNA was identified in 16 patients (27.6%). In the material from 31 diagnostic specimens of normal conjunctiva (group 2), the presence of HPV was demonstrated in three cases (9.7%). A statistically significant difference was found in the presence of HPV DNA between the patients from groups 1 and 2 (p = 0.041). HPV type 16 was most common and was demonstrated in 56% of HPV-positive cases of pterygium. HPV 16 and HPV 6 co-infections were found in 19% of cases, while HPV 18 and HPV 6 co-infections were observed in 13%. In group 2, all three patients with HPV showed HPV 18.

CONCLUSION

It seems that HPV is not necessary to induce pterygium; however, it might play a synergistic role in the multi-stage process of its development.

Investigation of human papillomavirus and Epstein-Barr virus DNAs in pterygium tissue

PURPOSE

Recent studies postulated the presence of a probable relationship between pterygium and neoplasia. This study aimed to investigate the role of two oncogenic viruses, human papillomavirus (HPV) and Epstein-Barr virus (EBV), in the development of conjunctival pterygia.

METHODS

Polymerase chain reaction was used to identify the presence of HPV and EBV in 30 primary and 10 recurrent pterygia samples. Twenty conjunctival samples obtained from patients undergoing cataract surgeries were used as the control group. Patient groups had similar sex, race, and age distribution to eliminate bias. For exploration of HPV in groups, two different PCR methods (in-house PCR with two different primer sets and one real-time PCR method) were studied. The presence of EBV was shown by real-time PCR method.

RESULTS

HPV was identified in none of the pterygia and control group patients. However, EBV was detected in 3 out of 30 (10%) primary pterygia patients and in none of the recurrent pterygia and control patients.

CONCLUSIONS

Up to now, HPV has been blamed as the major viral pathogen in the etiopathogenesis of pterygium. The current results suggest that EBV may also be involved in the pathogenesis of pterygium, but further larger studies with larger cohorts are required to confirm this hypothesis.

Expression of neurotrophic factors in human primary pterygeal tissue and selective TNF-alpha-induced stimulation of ciliary neurotrophic factor in pterygeal fibroblasts

Pterygium is a degenerative, fibrovascular and hyperplastic growth resulting from a proliferative tissue actively growing from altered limbal stem cells at the corneal-conjunctival junction. However, the pathogenesis of pterygium is still unclear. The aim of this study was to determine the expression of neurotrophic factors (nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), and neurotrophin (NT)-3, NT-4/5) in pterygeal tissue and to confirm whether tumor-necrosis factor-alpha (TNF-alpha) modulates the expression of these neurotrophic factors in primary cultured pterygeal fibroblasts. We looked for expression of these neurotrophic factors in surgically excised pterygia and normal donor limbal tissues by immunohistochemistry and in primary cultured pterygeal and normal subconjunctival Tenon's fibroblasts by Western blot and reverse transcription-polymerase chain reaction (RT-PCR). Expression of CNTF and NT-4/5 is increased in pterygeal tissues compared with normal tissue, and production of CNTF is stimulated in pterygeal fibroblasts by TNF-alpha but not in normal fibroblasts. This selective stimulation of CNTF in pterygeal fibroblasts suggests that CNTF may play a role in the pathogenesis of pterygium.

Herpes simplex virus and pterygium in Taiwan

PURPOSE

To evaluate the presence of herpes simplex virus (HSV) in pterygia to study the possible association between HSV and pterygia in Taiwan, a tropical country with a high prevalence of pterygium.

METHODS

Sixty-five pterygia, 10 normal conjunctiva, 8 conjunctival nevi, and 2 malignant conjunctival melanomas were obtained. Clinical histories were recorded for each patient. HSV detection was accomplished by polymerase chain reaction amplification of viral sequences. HSV-positive specimens underwent subsequent DNA in situ hybridization. Results were statistically analyzed.

RESULTS

By using polymerase chain reaction, HSV was detected in 3 (5%) pterygia, and no conjunctival control displayed HSV. All 3 HSV-positive pterygia studies were DNA in situ hybridization negative. There was no statistically significant correlation between pterygium and the presence of HSV.

CONCLUSIONS

HSV is not associated with pterygium formation in Taiwan; the pathogenesis of pterygia is still incompletely understood.

Expression of survivin protein in pterygium and relationship with oxidative DNA damage

Ultraviolet radiation is known to cause oxidative DNA damage and is thought to be a major factor implicated in the pathogenesis of pterygium. Among all the photo-oxidative DNA products, the 8-hydroxydeoxyguanosine (8-OHdG) is regarded a sensitive and stable biomarker for evaluating the degree of DNA damage. The protein p53 is a major cell stress regulator that acts to integrate signals from a wide range of cellular stresses. UV radiation has a carcinogenic effect resulting in DNA damaged cells with loss of normal growth control. This assumption is supported by the association between UV-B exposure and activation of survivin, a member of the inhibitor of apoptosis protein family (IAP), highly up-regulated in almost all types of human malignancy. In this study we demonstrate, for the first time in pterygium, the immunohistochemical presence of survivin, and investigate the correlation between survivin, p53 and 8-OHdG. Our results demonstrate that oxidative stress could lead to a significant activation of survivin expression, suggesting that this might be an important event in the development of pterygium, inducing and supporting a hyperproliferative condition. Survivin expression in pterygium would counteract UV-B-induced apoptosis and would cooperate with loss of p53. The co-operation between survivin and functional loss of p53 might provide a general mechanism for aberrant inhibition of apoptosis that could be responsible for the development of pterygium and its possible progression to neoplasia.

Role of concanavalin A lectin in recognition of pterygium remnant after surgical excision: preliminary results of a prospective study

Background:

Pterygium is one of the most common conjunctival diseases among ophthalmic pathologies. The frequency of recurrences is high, either after surgical treatment or after treatment combined with mitomycin C or beta-radiation therapy.

Aims:

The purpose of this study was to determine whether concanavalin A (ConA) lectin bound to the pterygial surface can be used to detect recurrence or remnants of pterygium after surgical excision.

Materials and Methods:

This was a prospective study on 20 patients with pterygium, divided in five stages, pre-surgery, early post-surgery (24h), late post-surgery (seven days), very late post-surgery (four weeks) and two months after the procedure.

A drop of fluorescein-marked Con A (35 µg/mL) was instilled in the lower conjunctival eyelid sac and the eye was exposed to the light of a Wood′s lamp for an average of five seconds.

Results:

Out of the 20 patients, eight patients were found to have fluorescent stretch marks over the scar corresponding to residual pterygial tissue at four weeks; two months after the procedure of re-surgery we observed no fluorescent remnants. All residual pterygia were confirmed through histochemistry studies.

Conclusion:

It was possible to detect remnants of pterygium in postoperative patients and recurrences in early pre-clinical stages through the visualization of fluorescent ConA bound to the pterygial surface.

Human papillomavirus and pterygium. Is the virus a risk factor?

BACKGROUND

Pterygium is a disease of unknown origin and pathogenesis that might be vision threatening. It is characterised by a wing-like conjunctival overgrowth of the cornea. Several studies have investigated human papillomavirus (HPV) as a risk factor for the development of pterygia, but the results are inconclusive.

AIM

To investigate a large sample of pterygia for the presence of HPV in order to clarify the putative association between pterygia and HPV.

METHODS

100 specimens of pterygium from Danish patients and 20 normal conjunctival biopsy specimens were investigated for the presence of HPV with PCR technique using beta-globin primers to access the quality of the extracted DNA and the HPV primers MY09/11 and GP5+/6+. HPV-positive specimens underwent subsequent HPV typing with type-specific HPV primers and further investigation with DNA in situ hybridisation (ISH).

RESULTS

90 of 100 investigated pterygia proved suitable for HPV analysis by PCR. As beta-globin could not be amplified, 10 specimens were excluded from the study. 4 of 90 pterygia harboured HPV. HPV type 6 was identified in all four HPV-positive pterygia. The 20 normal conjunctival biopsy specimens were beta-globin positive and HPV negative. All four pterygia that were HPV type 6 positive were DNA ISH negative.

CONCLUSIONS

The low presence of HPV DNA in pterygia does not support the hypothesis that HPV is involved in the development of pterygia in Denmark.

The risk of pterygium in salt workers

PURPOSE

To find out if exposure to direct and reflected sunlight in brine pans (ground water rich in salt, kept in wide pans in open air for salt manufacturing), increases the risk of pterygium in exposed salt workers.

METHODS

It was a cross sectional observational study, in which 865 salt workers were examined in the Free Occupational Health Check-up camps held near salt sites; 304 persons from the same area engaged in other work were examined as controls. The prevalence of pterygium in different age groups was compared between brine workers (who worked in the brine pans), dry salt workers, (who were engaged in the loading, weighing, milling, packing or transportation of the dry salt but never worked in brine pans) and non-salt-worker controls.

RESULTS

The prevalence of pterygium was significantly higher in brine workers (21.0%) as compared to dry salt workers (9.1%) (Yates corrected chi(2) = 23.45, p = 0.000001) and non-salt-worker controls (9.4%) (Yates corrected chi(2) = 15.69, p = 0.00007). It increased with age and duration of employment in the salt industry.

CONCLUSIONS

Brine workers have a higher risk of developing pterygium probably due to their exposure to sunlight reflected both from the surface of brine and from the surface of salt crystals.

Finding of conjunctival melanocytic pigmented lesions within pterygium

AIMS

Conjunctival pigmented lesions have characteristic clinical and histopathological appearances. Melanocytic pigmented lesions commonly occur in the conjunctiva, although they have not been previously reported in pterygium, a common lesion which originates from conjunctiva. Our aim was to evaluate the possibility of an association between pterygium and conjunctival melanocytic pigmented lesions.

METHODS AND RESULTS

A total of 80 samples of pterygium excised from Ecuadorian patients in 2002 were collected. Clinical data were available regarding age, sex, race and place of residence. Histological sections were evaluated for the presence of melanocytic pigmented lesions. Nine cases of conjunctival melanocytic, pigmented lesions within pterygium were found and were classified according to the histopathological criteria previously published for pigmented lesions of the conjunctiva, as naevi and primary acquired melanosis (PAM) with varying degrees of atypia. Five of the nine cases showed primary acquired melanosis without atypia, while two cases had atypia; one case showed features of compound naevus and one lesion was designated as subepithelial naevus.

CONCLUSIONS

Our findings suggest that conjunctival melanocytic, pigmented lesions occasionally occur in pterygium. All surgically removed pterygia should undergo careful histopathological examination.

Frequency of Chromosome 17 Aneuploidy in Primary and Recurrent Pterygium by Interphase-Fluorescence in situ Hybridization

AIM

To investigate chromosome 17 numerical aberrations by using fluorescence in situ hybridization (FISH) in pterygia and to find out whether there is any association between chromosome 17 aneuploidy and recurrent pterygia.

METHODS

Pterygium tissue samples were taken from 21 patients by surgical excision. Eighteen of them had primary and 3 had recurrent pterygium. Peripheral whole blood interphase cells obtained from 11 healthy subjects were assigned as control group. The cells from pterygium tissue and peripheral blood were incubated with a hypotonic solution and fixed in order to obtain interphase nuclei. FISH analysis with chromosome-17-specific alpha-satellite DNA probe was performed on both the interphase nuclei of pterygium tissue (of patients) and peripheral whole blood cells of controls.

RESULTS

The mean percentage of chromosome 17 aneuploidy was 4.71% for the pterygia group and 4.41% for the controls. No significant difference of chromosome 17 aneuploidy was observed between the patients and the controls. When the group of patients with recurrences was compared with the group without recurrences, there was a significant difference in the frequency of chromosome 17 aneuploidy (U = 17, p = 0.029).

CONCLUSIONS

Chromosome 17 aneuploidy is probably not an important factor in the formation of pterygium, but it may be related to recurrence.

The involvement of adult stem cells originated from bone marrow in the pathogenesis of pterygia

Pterygium is a proliferative disease. Recent research has reported that stem cells are involved in the pathogenesis of various proliferative diseases, including solid tumors and diabetic proliferate vitreoretinopathy. In previous literature, we hypothesized that adult stem cells originated from bone marrow were involved in the pathogenesis of pterygium. We proved this by immunohistochemical staining with various stem cell markers. The staining showed adult stem cells in the pterygium. c-kit positive cells were observed primarily in the stroma, and some cells were also found in the basal epithelium. AC133 and CD34 positive cells were primarily found in the basal epithelium and were ovoid shaped, similar to the c-kit cells. However, some cells were found in vascular endothelium. STRO-1 positive cells were found mainly in the stroma and were spindle shaped. In recurrent pterygium, cells were more scattered and the expression pattern was denser. Therefore, we suggest a new theory of pterygium pathogenesis. Inflammation caused by environmental factors triggers the abnormal production of some growth factors and cytokines in order to recover from cellular damage. If these healing signals are excessive, limbal basal cells will be changed to abnormally-altered pterygial cells. The excessive wound healing process and remnant altered cells result in recurrence using the same mechanism.

Loss of 10p material in a child with human papillomavirus-positive disseminated bilateral retinoblastoma

Retinoblastoma (RB) is a malignant childhood tumor that results from loss or inactivation of both alleles of the RB1 gene. Human papillomavirus (HPV) DNA sequences have been found in RB tissue, suggesting a role of the viral infection with RB. We here describe a child with disseminated bilateral RB without familial history, who displayed a loss of material from 10p. Fluorescence in situ hybridization studies showed a somatic loss of both alleles of the RB1 gene. Moreover, sequences for HPV-6a were detected on DNA extracted from eye tumor tissue and from nonstimulated peripheral blood leukocyte cultures. The eye tumor tissue was also positive for HPV L1 viral proteins. Repeated loss of the short arm of chromosome 10 in HPV-transfected keratinocytes has been reported. Loss of heterozygosity in 10p14 approximately p15 is also frequent in cervical cancers. Therefore, it seems probable that the abnormalities on 10p detected in the present case are related to the HPV infection. Thus, HPV could be a cofactor in the progression of RB by promoting nonrandom additional mutations.

Increased oxidative DNA damage, 8-hydroxydeoxy- guanosine, in human pterygium

PURPOSE

Chronic exposure to ultraviolet (UV) light is a widely accepted aetiological factor in the development of pterygium. UV radiation may induce production of reactive oxygen species via photosensitized oxidation, thus causing oxidative damage. This study was conducted to test the hypothesis that oxidative damage to DNA is increased in pterygium.

METHODS

Immunohistochemical analysis employing a monoclonal antibody specific for 8-hydroxy-2'-deoxyguanosine (8-OHdG), a ubiquitous maker of oxidative stress, was performed in three patients with primary pterygium. The levels of 8-OHdG in DNA isolated from the other 29 pterygium specimens and their adjacent normal conjunctival tissues were determined using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Immunohistochemistry of 8-OHdG showed a distinct pattern of more extensive and intense staining in the nuclei of pterygium tissue compared with that in their adjacent normal conjunctiva. ELISA also revealed that the average level of 8-OHdG in the pterygium tissues was 4.7-fold higher than that of the corresponding normal conjunctiva (P<0.001).

CONCLUSIONS

The increased levels of 8-OHdG in the pterygium tissues indicate that oxidative stress could play a role in the development of pterygium. These findings provide new information to better understand the pathogenesis of pterygium and are useful in the prevention and treatment of this disease.

Caspase-3-dependent apoptosis in cardiac myxoma: not associated with human papillomavirus or Epstein-Barr virus

Cardiac myxoma is the most common tumor of the heart, has a variable clinical presentation and immunohistochemical profile. Viral infections, such as herpes simplex virus, human papillomavirus (HPV), and Epstein-Barr virus (EBV), may play an important role in the causes of cardiac myxoma. This investigation will demonstrate caspase-3-dependent apoptosis in cardiac myxoma without HPV or EBV infection. This study included 15 patients with cardiac myxoma, who were treated with surgical excision of the lesion. Data were collected on detailed clinical parameters. Terminal deoxynucleotidyl transferase nick-end labeling assay, electrophoresis, and caspase-3 immunohistochemical studies were performed to characterize apoptosis. Genechip containing 39 subtypes was used to elucidate HPV; and polymerase chain reaction to detect LMP-1 gene of EBV. The patient population comprised of eight (53%) women and seven (47%) men. The mean age of patient participants was 45 years, with an age range of 30-70 years. All patient cases were sporadic myxomas rather than familial myxomas. The patient presentations included dyspnea (53%), asymptomatic (27%), stroke (7%), chest pain (7%), and fever (7%). All lesions were located in the left atrium. The individual patient cases of myxoma did not differ in location or clinical event in terms of pathological scores, such as vascular proliferation, inflammation, cellularity, hyaline, calcification, or thrombosis. Cardiac myxoma is characterized by apoptosis through caspase-dependent pathway. HPV or EBV was not detected in any of the study patient samples. In conclusion, no viral genomes of HPV or EBV were detected in these 15 patients. This study demonstrates that caspase-3-dependent apoptosis in cardiac myxoma is not dependent on concurrence of previous HPV and/or EBV infection.

[Association of malignant tumors of the conjunctiva and HIV infection in Kinshasa (D. R. Congo). First results]

BACKGROUND

Conjunctival carcinomas are tumors especially of the 6th/7th decades. They occur in Germany with a frequency of 1/20,000. For years it has been well known that in Africa the number of malignant tumors of the conjunctiva has been increasing. The reasons for that are not well known. HIV is a possible pathogenetic cofactor.

METHOD

A histological examination of 34 specimens was performed in Rostock on conjunctival tumors removed at the Ophthalmologic Department of the University of Kinshasa in 2001. The study included 23 female and 11 male patients aged 20-75 years (mean 42). All patients underwent serological investigation for HIV infection.

RESULTS

Of 34 patients 18 were HIV positive. Of the HIV-positive patients, six had a squamous cell carcinoma, seven a CIN (conjunctival intraepithelial neoplasia) I-III, and five a pinguecula. Of the HIV-negative patients, five showed a squamous cell carcinoma, eight a CIN I-III, one a pinguecula, one a sebaceous gland carcinoma, and one a papilloma. The average age of the HIV-positive patients with a squamous cell carcinoma was 41 years compared to the HIV-negative patients with 58 years.

CONCLUSIONS

There was no difference in frequency of conjunctival intraepithelial neoplasia between HIV-positive or HIV-negative patients. HIV-positive patients with a squamous cell carcinoma were on average 17 years younger. UV radiation is the main risk factor and HIV infection is a possible carcinogenic cofactor. Investigations on additional viral infections as possible pathogenetic factors and on changed tumor suppressor genes are needed.

Genetic polymorphism of hOGG1 and risk of pterygium in Chinese

PURPOSE

Ultraviolet irradiation is known to cause oxidative DNA damage and is thought to be a major factor implicated in the pathogenesis of pterygium. The highly mutagenic 8-hydroxy-2'-deoxyguanosine, a marker for the evaluation of photo-oxidative DNA damage, can be repaired by human 8-oxoguanine glycosylase I (hOGG1). A transition of C to G at nucleotide position 1245 in exon 7 of the hOGG1 gene is associated with the substitution of cysteine for serine at codon 326. In this study, we investigated the association of the hOGG1 Ser326Cys polymorphism with pterygium in a Chinese population.

METHODS

In all, 70 patients and 86 controls were enrolled in this study. The Ser326Cys polymorphism was determined by the polymerase chain reaction-restriction fragment-length polymorphism analysis. The association between this genetic polymorphism and risk of pterygium was examined by chi(2)-test and logistic regression.

RESULTS

The allelic frequencies for the Ser and Cys variants of hOGG1 gene were not significantly different between the two groups. However, when compared with Ser/Ser and Ser/Cys genotypes combined, we found that the homozygous Cys/Cys genotype was more prevalent in pterygium patients than controls (P=0.024) with the odds ratio being 2.2 (95% CI: 1.1-4.5). In the pterygium group, the mean age of patients with the Cys/Cys genotype was younger than those with the other two genotypes (P=0.025).

CONCLUSIONS

Our findings suggest that the 1245C --> G transition in exon 7 of the hOGG1 gene, which results in Ser326Cys substitution of the enzyme, might play a role in the susceptibility of humans to pterygium.

Detection of point mutations at codon 12 of KI-ras in ophthalmic pterygia

AIMS

Ophthalmic pterygium is a potentially vision-threatening lesion of unknown etiology, related to an exposure to solar light. Mutations to the ras genes are frequently observed in lesions related to an exposure to solar light. The present study aims at screening pterygia for mutations at codons 12 and 13 of the ras genes.

METHODS

In all, 50 pterygia were examined, together with respective blood samples and specimens of normal conjunctiva. A PCR reaction was performed to amplify sequences containing codons 12 and 13 of Ki-ras, H-ras, and N-ras. An RFLP analysis was then performed to detect point mutations at codon 12. The mutational status at codons 12 and 13 was further explored with sequencing of PCR products.

RESULTS

RFLP analysis revealed Ki-ras mutations at codon 12 in five (10%) of pterygia, whereas H-ras or N-ras mutations were not observed. Sequencing confirmed Ki-ras mutations at codon 12 and revealed absence of mutations at codon 13. The presence of Ki-ras mutations was significantly correlated with postoperative recurrence (P=0.02) and young age (P=0.04). Mutations were not observed in specimens of blood or normal conjunctiva for any of the genes examined.

CONCLUSIONS

The absence of N-ras mutations is in agreement with previous reports concerning mucosal lesions. The detection of Ki-ras mutations and the association with postoperative recurrence implies a possible role of Ki-ras in the clinical profile of pterygium. The mechanism of Ki-ras mutations is unclear and could be independent of the action of UV light.

Pathogenesis of pterygia: role of cytokines, growth factors, and matrix metalloproteinases

Pterygium is a common ocular surface disease apparently only observed in humans. Chronic UV exposure is a widely accepted aetiological factor in the pathogenesis of this disease and this concept is supported by epidemiological data, ray tracing models and histopathological changes that share common features with UV damaged skin. The mechanism(s) of pterygium formation is incompletely understood. Recent data have provided evidence implicating a genetic component, anti-apoptotic mechanisms, cytokines, growth factors, extracellular matrix remodelling (through the actions of matrix metalloproteinases), immunological mechanisms and viral infections in the pathogenesis of this disease. In this review, the current knowledge on pterygium pathogenesis is summarised, highlighting recent developments. In addition, we provide novel data further demonstrating the complexity of this intriguing disease.