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PubMed2002

[Clinical observation on fresh amniotic membrane transplantation for treatment of recurrent pterygium].

PURPOSE: To observe the effect of retrograding excision of pterygium with amniotic membrane transplantation on the prevention of pterygium relapse. METHODS: Incisions of conjunctiva were made along both sides of pterygium body. The conjunctiva was then separated from the underlying pterygium tissue and cut at the side of pterygium body. It was further separated from the underlying pterygium tissues toward the caruncle so that the pterygium tissue could be exposed, which was separated from the sclera and then was excised at the site of the plicae semilunaris and separated from the cornea retrogressively. The exposed sclera was then covered by transplanted amniotic membrane. RESULTS: After 6 - 19 months of follow-up, two in 60 eyes of pterygium relapsed, recurrent rate 3. 3%. No immune rejection, necrosis and graft absorption were found. CONCLUSION: Retrograding excision of pterygium with fresh amniotic membrane transplantation can significantly decrease the relapse of pterygium. Amniotic membrane transplantation is a reasonable method for treatment of pterygium. Fresh amniotic membrane transplantation has advantages of easily obtain, convenient usage, and lower cost, which is suitable in local hospital of our country.

Adult↗
PubMed2001

Pterygium-induced corneal astigmatism.

A significant degree of corneal astigmatism can be induced by the encroachment of a pterygium onto a cornea. The pterygium generally causes with-the-rule corneal astigmatism that is hemimeridional on the side of the pterygium. There is a significant correlation between the extension of the pterygium onto the cornea and the amount of induced astigmatism. However, there is a poor correlation between pterygium-induced astigmatism measured topographically and that measured by manifest refraction. Successful pterygium surgery will reduce pterygium-induced refractive astigmatism and improve visual acuity. This paper outlines the management of a patient with an advanced pterygium, in whom a large degree of corneal astigmatism was induced by the encroachment of a pterygium onto the cornea. Subsequent excision of the pterygium brought about a reversal of the pterygium-induced corneal astigmatism.

Journal Article↗
PubMed2002

Ocular surface changes in pterygium.

PURPOSE: To evaluate ocular surface abnormalities in eyes with pterygium. METHODS: Impression cytology was performed on 56 pterygia in 50 eyes with primary or recurrent pterygium. Superior, inferior, nasal, and temporal bulbar conjunctivae were evaluated. RESULTS: The ocular surface morphology directly over the pterygium was found to be abnormal in 100% of cases. This was significant compared with abnormalities in 2.4% in the superior bulbar conjunctiva, 54.5% in the inferior bulbar conjunctiva, and 58.1% in the clinically unaffected interpalpebral conjunctiva. The epithelial cells in pterygium demonstrated squamous metaplasia in 73.2% of cases, with marked enlargement and elongation of the cells and pyknotic changes in the nuclei. Squamous metaplasia was also seen in the inferior conjunctiva (31.7%) and the clinically unaffected interpalpebral conjunctiva (54.8%) but without the advanced changes seen over the pterygium (p < 0.001). A low cellular yield was obtained over the pterygium in 98.2% of cases but only 22.7% in the inferior conjunctiva and 22.6% in the clinically unaffected interpalpebral conjunctiva (p < 0.001). Mucinous hyperplasia signifying increased goblet cell density was observed over the surface of the pterygium in 87.5% compared with 2.4% in the superior conjunctiva, 15.9% in the inferior conjunctiva, and 12.9% in the clinically unaffected interpalpebral conjunctiva (p < 0.001). CONCLUSION: The cytology of surface cells in pterygium exhibits squamous metaplasia with increased goblet cell density. A graded series of ocular surface changes exists throughout the bulbar conjunctiva in eyes with pterygium, with the most advanced changes occurring directly over the pterygium surface.

Adult↗
PubMed2001

[Effectiveness of conjunctival autograft transplantation in pterygium surgery].

INTRODUCTION: Pterygium is a fibrovascular overgrowth of bulbar cunjonctiva over the cornea and may produce visual impairment. Many surgical techniques and adjunctive therapies have been proposed but recurrence remains frequent. MATERIALS AND METHODS: We report a prospective study of 52 eyes treated by limbal conjunctival autograft for primary and recurrent pterygium. We compare our results with the technique of simple excision performed in 111 cases of pterygium (3 being a recurrent pterygium). RESULTS: The mean age of the patients was 45 years. 30 cases of pterygium were primary (57.7%) and 22 were recurrent (42.3%). After an average follow-up of 14 months, the incidence of recurrence was 10%. Only 2 of these recurrent cases of pterygium were primary. DISCUSSION: Conjunctival autograft is a simple, safe, and highly effective procedure for the treatment of pterygium. It reduces the rate of recurrence more than simple excision (55.9% after a follow-up of 1 year). CONCLUSION: The introduction of limbal conjunctival autograft for the treatment of pterygium meets three main goals: safety, good optical outcome and a lower rate of recurrence. This procedure could be accepted as a successful technique for cases with recurrent pterygium specially in younger patients and when the environment al factors lower the development of recurrent pterygium.

Adult↗
PubMed2003

The role of ultraviolet irradiation and heparin-binding epidermal growth factor-like growth factor in the pathogenesis of pterygium.

Ultraviolet (UV) light is one of the major factors implicated in the pathogenesis of pterygium. The mechanism by which UV light induces this disease remains elusive. The aim of this study was to evaluate the effects of UVB irradiation on the expression of growth factors in cultured pterygium epithelial cells and to demonstrate their distribution within pterygium. We cultured pterygial epithelial cells from pterygium explants and these cells were exposed to 20 mJ/cm(2) of UVB. Total RNA was extracted at 0, 6, and 12 hours after irradiation. (32)P-labeled cDNA was synthesized and analyzed using microarray technology to determine the differential expression of 268 growth factor and cytokine related genes. Semiquantitative reverse transcriptase-polymerase chain reaction was used to corroborate this data. Conditioned media derived from cells exposed to UVB irradiation was analyzed for protein expression by enzyme-linked immunosorbent assay. Immunohistochemistry was used to evaluate the distribution of heparin-binding epidermal growth factor-like growth factor (HB-EGF) in pterygium tissue. Analysis of the hybridization signals revealed that the genes encoding HB-EGF, fibroblast growth factor 3, and cytotoxic trail ligand receptor were consistently elevated at 6 and 12 hours after UVB treatment. HB-EGF mRNA was elevated 6.8-fold at 6 hours after irradiation and was augmented in culture supernatants after the same treatment. Furthermore, HB-EGF reactivity was identified in the epithelium and vasculature of pterygium by immunohistochemistry. HB-EGF was present in normal limbal epithelium, although it was not induced in cultured limbal epithelial cells by UV irradiation. HB-EGF is a potent mitogen, localized in pterygium tissue, and significantly induced by UVB in pterygium-derived epithelial cells. We postulate that this growth factor is a major driving force in the development of pterygia and a means by which UV irradiation causes the pathogenesis of pterygium.

Cell Culture Techniques↗
PubMed2000

Effects of pterygium on corneal spherical power and astigmatism.

OBJECTIVE: To evaluate prospectively the corneal refractive status before and after pterygium surgery and its relationship with preoperative pterygium size. DESIGN: Prospective, nonrandomized, comparative (self-controlled) trial. PARTICIPANTS: One hundred thirty-six eyes undergoing primary pterygium removal surgery. MAIN OUTCOME MEASURES: Corneal spherical power, astigmatism, surface regularity index (SRI), and surface asymmetry index (SAI) before and after surgery, and the preoperative pterygium size. RESULTS: Before surgery, pterygium size significantly correlated with spherical power (Pearson's correlation coefficient, r = -0.370, P < 0.001), astigmatism (r = 0.600, P < 0.001), SRI (r = 0.367, P < 0.001), and SAI (r = 0.387, P < 0.001). The surgery significantly increased spherical power of the cornea, whereas astigmatism, SRI, and SAI were significantly decreased by the surgery (P < 0.01, paired t test with Bonferroni's correction of P value for multiple comparison). Surgically induced changes in spherical power (r = 0.598, P < 0.001) and astigmatism (r = 0.653, P < 0.001) significantly correlated with the preoperative pterygium size. Precise prediction of the magnitude of refractive changes based on the preoperative pterygium size was difficult. CONCLUSIONS: The presence of pterygium and its removal significantly influence the corneal refraction including spherical power, astigmatism, asymmetry, and irregularity, with the larger pterygium exerting the greater influence.

Adult↗
PubMed2005

Evaluation of TNF-alpha and IL-1beta polymorphisms in Taiwan Chinese patients with pterygium.

PURPOSE: Pterygium, a complex disease, is associated with ultraviolet radiation, immunoinflammatory process, genetic factors, and virus infection. Ultraviolet radiation induces secretion of proinflammatory cytokines by the ocular surface epithelium, inflammatory cells in the tear fluid, or both. Among these cytokines, tumour necrosis factor (TNF)alpha and interleukin (IL)-1beta activate pterygium body fibroblasts, resulting in a phenotype capable of expressing various proteinases associated with extracellular matrix remodelling, angiogenesis, and fibroblast proliferation, which are important for pterygium formation and recurrence. The genetic factor was proposed to play a role in pterygium formation, but there were few studies to clarify this proposition. For investigating genetic factors, the association between pterygium and TNF-alpha and IL-1beta polymorphisms is evaluated in this study. METHODS: A total of 128 pterygium patients and 103 volunteers without pterygium were enrolled in this study. Polymerase chain reaction-based analysis was used to resolve the TNF-alpha-308 promoter, IL-1beta-511 promoter, IL-1beta exon 5, and IL-1 receptor antagonist (IL-1 Ra) polymorphisms. RESULTS: There were no significant differences in the frequency of genotypes and alleles of TNF-alpha-308 promoter, IL-1beta-511 promoter, IL-1beta exon 5, and IL-1 Ra polymorphisms between both groups. CONCLUSIONS: The correlation between pterygium and TNF-alpha-308 promoter, IL-1beta-511 promoter, IL-1beta exon 5, and IL-1 Ra polymorphisms does not exist and those polymorphisms are not useful genetic markers for pterygium susceptibility. Further studies on other polymorphisms or haplotypes of TNF-alpha and IL-1beta are necessary.

Adult↗
PubMed2005

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.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2006

Endothelial progenitor cells in pterygium pathogenesis.

PURPOSE: The pathogenesis of pterygium is not well known, and controversy exists about the cell origins and the nature of initial trigger required for its development. We investigated whether endothelial progenitor cells (EPCs) are involved in pathogenesis of pterygium and the mechanism underlying the selective recruitment of EPCs during this process. METHODS: We studied 13 normal controls and 28 pterygium patients (primary (n=15), recurrent (n=13)). Substance-P, vascular endothelial growth factor (VEGF), and stem cell factor (SCF) were measured in plasma and tears using ELISA, and circulating CD34(+) and c-kit(+) mononuclear cells (MNCs) by flow cytometry. Anterior segment fluorescein angiography (FAG) was performed to evaluate hypoxic conditions in the early stage of pterygium. Surgically removed pterygial tissues were analyzed immunohistochemically using the progenitor cell markers, CD34, c-kit, VEGFR-1, and VEGFR-2. RESULTS: Anterior segment FAG findings showed an increase in non-perfusion areas and attenuated vessels in the nasal limbus during early-stage pterygium. Circulating CD34(+) MNCs and c-kit(+) MNCs were increased in pterygium groups compared with normal controls. Systemic and local cytokines including SP, VEGF, and SCF in pterygium groups were also elevated and showed positive correlations with CD34(+) and c-kit(+) MNC numbers. Immunohistochemical analysis of pterygium showed strong progenitor cell marker immunoreactivities. CONCLUSIONS: EPCs might be involved in pterygium development, and ocular hypoxia triggers this neovascularization by recruiting EPCs derived from the bone marrow via the production of systemic and local cytokines.

Age Distribution↗
PubMed2000

Evaluating pterygium severity: a survey of corneal specialists.

PURPOSE: Accurate and reliable evaluation techniques are essential for clinical and epidemiologic studies. This survey of corneal specialists was designed to lay a foundation for the further development of methods for evaluating and staging pterygium. METHODS: In a self-administered, mailed questionnaire, 213 corneal specialists rated the importance of nine symptoms, nine signs, and nine clinical tests for the severity of primary pterygium. Severity was defined as the present need for surgical intervention. RESULTS: The most important factors for determining primary pterygium severity were the extent of encroachment onto the cornea, decreased visual acuity, restricted ocular motility, and increased rate of growth. Many patient symptoms were rated as moderately to highly important. The questionnaire was shown to have good response reliability by test-retest comparisons. Cronbach's alpha was 0.89, which indicates very good internal consistency reliability. CONCLUSION: The survey identifies the priorities of experts in determining the severity of pterygium. More precise and clearly defined evaluation methods will enhance future clinical and epidemiologic studies of pterygium. The ranked list of pterygium signs, symptoms, and tests can serve as a guide for developing pterygium evaluation methods in the future. There is a need for a method that accurately and precisely quantifies the distance of pterygium encroachment onto the cornea and the pterygium progression rate. Furthermore, there is a need for an assessment of patient symptoms.

Health Surveys↗
PubMed2000

Inhibitory effects of tranilast on the proliferation and functions of human pterygium-derived fibroblasts.

PURPOSE: We studied the possibility that tranilast, an antiallergic and antiproliferative drug, may be beneficial for the treatment of pterygium. METHODS: Pterygium-derived cells were identified by immunohistochemical methods. Growth rate of pterygium-derived cells was determined by using a hemocytometer. Chemotaxis was determined in a microchemotaxis chamber. Pterygium-derived cells were cultured on floating collagen gel, and the contracted diameter was measured. Collagen synthesis by pterygium-derived cells was determined by the collagenase digestive method. Tranilast was added to the culture medium at final concentrations of 0, 12.5, 25, 50, and 100 microg/ml. RESULTS: Pterygium-derived cells were stained with anti-prolylhydroxylase and anti-alpha-smooth muscle actin, and identified as fibroblasts. Tranilast inhibited the proliferation and chemotaxis of pterygium-derived fibroblasts, and the collagen-gel contraction induced by these cells, but it exerted no inhibitory action on collagen synthesis by pterygium-derived fibroblasts. CONCLUSION: Tranilast may be useful for suppressing the recurrence and, possibly, the development of pterygium.

Actins↗
PubMed2003

Combined mitomycin C application and free flap conjunctival autograft in pterygium surgery.

PURPOSE: To evaluate the long-term postoperative outcome and complication rate of combined intraoperative low-dose mitomycin C application and free conjunctival autograft for the treatment of pterygium. METHODS: In a prospective, consecutive, noncomparative case series, a series of 46 consecutive patients (50 eyes) with primary pterygium (43 eyes) or recurrent pterygium (7 eyes) were studied. The patients' ages ranged from 23.0 to 80.0 years (mean, 53.4 years). All patients underwent pterygium excision combined with intraoperative low-dose mitomycin C application (0.02% for 2 minutes) and free conjunctival autograft. The mean follow-up period was 29.2 months (range 12 to 41 months). The main outcome measures were recurrence of pterygium and postoperative complications. RESULTS: Pterygium recurred to a small extent (0.5 mm) in one eye (2%) of a patient with recurrent pterygium. There were no intraoperative complications. Subconjunctival graft hematoma appeared soon after surgery and resolved spontaneously in five eyes (10%). One eye developed transient high intraocular pressure without optic nerve or visual field defect, and one eye developed mild symblepharon. There were no sight-threatening complications or serious side effects. CONCLUSIONS: By applying a single low dose of mitomycin C combined with free conjunctival autograft during pterygium excision, the recurrence rate of pterygium can be markedly reduced.

Adult↗
PubMedDate not supplied

Comparison between the role of intraoperative mitomycin C and doxorubicin in preventing the recurrence of primary pterygium.

PURPOSE: The purpose of this study was to compare the role of intraoperative mitomycin C (MMC) and doxorubicin in preventing the recurrence of primary pterygium. MATERIALS AND METHODS: Fifty-six patients including 22 males and 34 females in the age range of 22-55 years (mean age 38.1 years +/- 10.7) having primary pterygium of progressive type were randomly divided into two groups. The first group of patients was treated with intraoperative MMC (0.02% for 3 min) and in the second group intraoperative doxorubicin (0.02% for 3 min) was used. The patients were regularly followed until 1 year postoperatively for examining visual acuity, wound condition, adverse events and recurrence of pterygium. RESULTS: The mean age of patients of MMC group was 37.4 +/- 11.0 years and of doxorubicin group was 38.8 +/- 10.8 years (difference statistically not significant). All these patients had pterygium on the medial side of cornea. The side effects experienced by our patients from the use of these agents were conjunctival hyperemia, conjunctival necrosis, corneal epithelial defect, subconjunctival hemorrhage, episcleritis, increased pain, foreign body sensation, lacrimation, irritation, diminution of vision and photophobia. Recurrence was seen in 4 patients of MMC group (14.3%) and 3 patients of doxorubicin group (10.7%) (difference statistically not significant; chi(2) = 0.16, p = 0.68). The recurrence of pterygium was not associated with age of patients, laterality of eye involved, amount of encroachment of pterygium over cornea, width of pterygium, preoperative complaints and postoperative adverse events. CONCLUSIONS: The two antimitotic agents, MMC and doxorubicin, when used intraoperatively along with primary pterygium excision, had a comparable role both in terms of adverse events and prevention of recurrence of pterygium.

Adult↗
PubMed2003

Overexpression of Insulin-like growth factor-binding protein-2 in pterygium body fibroblasts.

PURPOSE: To examine the expression pattern of insulin-like growth factor-binding protein (IGFBP)-2 in cultured primary pterygium fibroblasts and compare it with expression in normal conjunctival fibroblasts. METHODS: Profile of gene expression by normal conjunctival and primary pterygium fibroblasts was performed by using a cDNA microarray. The overexpression of IGFBP-2 thus identified was further confirmed by RT-PCR and Western blot analysis of cultured cells and by immunohistochemistry on primary pterygium and normal conjunctival tissue sections. RESULTS: A dramatically increased expression of IGFBP-2 mRNA was demonstrated in cDNA microarray membranes from two different pterygium fibroblasts. This finding was confirmed by RT-PCR in four additional different pterygium fibroblasts and by Western blot analysis of their culture supernatants. Immunohistochemistry of frozen sections from primary pterygium demonstrated increased staining in extracellular matrix of the stroma, compared with that of the normal conjunctiva. IGFBP-2 was also found in goblet cells of both normal conjunctival and pterygium epithelia. CONCLUSIONS: The increased expression of IGFBP-2 mRNA and protein in pterygium fibroblasts is further strong evidence to support the transformed phenotype of these cells and helps explain why there is increased growth of fibrovascular tissue. This phenotype may be used as a marker to assess the malignant nature of pterygium growth and recurrence.

Blotting, Western↗
PubMed2001

[The relation between expression of basic fibroblast growth factor and mast cells in pterygium].

OBJECTIVE: To examine the expression and distribution of basic fibroblast growth factor (bFGF) and mast cells in pterygium, and evaluate its effects in the pterygium formation and progression. METHOD: The expression of bFGF and mast cell tryptase in 17 primary pterygia, 6 recurrent pterygia and 6 normal conjunctival specimens were studied. The mast cell count and bFGF expression situation were observed. RESULTS: The bFGF was specifically localized in the epithelium, blood vessels and a subset of connective tissue cells. The bFGF expression was increased in the recurrent pterygium. The numbers of infiltrating mast cells (five 400 x sights) were (45.47 +/- 5.50) cells and (48.83 +/- 3.19) cells in the primary and recurrent pterygium respectively. In the comparisons between the cells in the pterygium (primary and recurrent) and (4.24 +/- 2.36) cells in the normal connective tissue, there were significant differences (F = 200.3128; q = 26.6762, 23.7341; P < 0.05). The shape and distribution of all the tryptase-positive cells (mast cells) in the pterygium tissues were similar to that of the cells with bFGF expression in the connective tissue. And the majority of bFGF-positive cells (87.54 +/- 3.60)% were similar to that of mast cells in the connective tissue. CONCLUSIONS: All infiltrating mast cells in pterygium have bFGF-positive expression. The bFGF expression is increased in the epithelium, blood vessels and infiltrating mast cells of the pterygium, and may contribute to the formation and progression of a pterygium.

Adult↗
PubMed2001

[Prevalence survey on pterygium in two counties of Hainan Province].

OBJECTIVE: To explore the relationship between pterygium and environmental condition, such as area and weather, and human factors, such as sex and race, through the prevalence survey of pterygium in Hainan Province. METHODS: As a sample, all villagers in 14 villages were chosen by random sampling from all the rural villages of Dongfang and Changjiang Counties, the pterygium was examined and their pterygia were recorded and graded according to the shape and the location of the head of pterygium. RESULTS: In 7 990 villagers examined, there were 628 cases with pterygium, prevalence being 7.86% and including 439 cases (8.28%) in 5 303 Han people and 189 cases (7.03%) in 2 687 Li people. The difference of the prevalence between Han and Li nationality was significant (chi(2) = 3.897, P = 0.048). There were 266 male cases (6.43%) and 362 female cases (9.40%). The prevalence in male was less than that in female (chi(2) = 19.852, P = 0.001). The distribution of the pterygium in eyes was symmetrical. CONCLUSION: The prevalence of pterygium in Hainan is higher than that in other provinces of China. It may be related to the geographic location and weather condition. In Hainan Province, the prevalence of pterygium in Han nationality is higher than that in Li nationality and in female higher than that in male. The increase of the prevalence of pterygium may be related to the increase of age.

Adolescent↗
PubMed2005

Oxidative DNA damage in pterygium.

PURPOSE: Epidemiological evidence suggests that UV irradiation plays the most important role in pterygial formation. The noxious effects of UV irradiation are either directly by a UV phototoxic effect or indirectly by formation of radical oxygen species (ROS). ROS are very harmful to cells, because they injure cellular DNA, proteins, and lipids (called oxidative stress). Among numerous types of oxidative DNA damage, the formation of 8-hydroxydeoxyguanosine (8-OHdG) presents only a minor fraction of UV induced DNA damage, but it is a ubiquitous marker of oxidative stress. If pterygium is related to UV, we surmised oxidative stress exists in pterygium. To provide the molecular evidence of UV radiation, 8-OHdG was detected in pterygium. Moreover, human 8-oxoguanine glycosylase (hOGG1) is the key component responsible for the removal of 8-OHdG. To determine whether the hOGG1 was expressed in pterygium, this enzyme was also evaluated. METHODS: Immunohistochemical staining using a monoclonal antibody to 8-OHdG and hOGG1 were performed on 52 pterygial specimens and 6 normal conjunctiva. RESULTS: There were 12 (23.1%) pterygial specimens positive for 8-OHdG staining, limited to the nuclei of the epithelial layer. No substantial staining was visible in the subepithelial fibrovascular layers. In pterygium with 8-OHdG staining, there were 4 (4/11, 36.4%) specimens with hOGG1 expression. However, in pterygium without 8-OHdG staining, there were only 3 (3/41, 7.3%) specimens with hOGG1 expression. hOGG1 expression was significantly associated with 8-OHdG positive staining. All normal controls were negative for 8-OHdG and hOGG1 staining. CONCLUSIONS: Our study demonstrated for the first time 8-OHdG in pterygium, which represented oxidative stress in pterygium. The increased level of 8-OHdG in pterygium is not due to decreased expression of hOGG1, while increased levels of 8-OHdG induced the expression of hOGG1.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2006

[Relationship between pterygium onset and ultraviolet rays exposure time].

OBJECTIVE: To investigate the dose-effect relationship between the radiation of ultraviolet ray and the onset of pterygium quantitatively. METHODS: Interrogation was conducted to 95 patients with pterygium in Yacheng district, Sanya City, Hainan Province, 37 males and 58 females, aged 55.7 +/- 13.8 (20 - 80), and 95 local volunteers in 1:1 pairs matched in age, sex, race, and similar habits of wearing glasses and caps (control group). Both the pterygium group and control group were re-divided into three sub-groups: youth (aged < or = 40), middle-aged (aged 41 - 60), and elderly (aged > 60). The time of exposing to ultraviolet ray was calculated. Photo of the pterygium was taken. The length of the pterygium invading into cornea was measured. RESULTS: The ultraviolet ray exposure time of the youth subgroup, pterygium group, was 35,637 +/- 13,587 hours, significantly higher than that of the youth subgroup, control group (26,188 +/- 17,423 hours, t = 3.352, P = 0.006). The ultraviolet ray exposure time of the middle-aged subgroup, pterygium group, was 73,412 +/- 23,082 hours, significantly higher than that of the middle-aged subgroup, control group (63,368 +/- 25,091 hours, t = 2.322, P = 0.024). However, there was no significant difference in the ultraviolet ray exposure time between the elderly subgroups of both groups. The length of the pterygium invading into cornea was positively correlated with the ultraviolet ray exposure time (r = 0.361, P < 0.05), and the length showed a trend of increased with aging. CONCLUSION: There is a certain dose-effect correlation between ultraviolet ray exposure and the etiology of pterygium.

Adult↗