Limbal epithelial stem-microenvironmental alteration leads to pterygium development

The effect of different pterygium surgery techniques on the ocular surface parameters in different durations: a systematic review and meta-analysis

PURPOSE

To evaluate the effects of different pterygium surgery techniques on ocular surface (OS) in different follow-up periods.

METHODS

PubMed, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wan Fang, and China Biology Medicine disc were searched for studies reporting pre- and post-operative OS parameters in pterygium.

RESULTS

A total of 33 articles were finally included. Three OS parameters showed relatively consistent changing trends after surgery including ocular surface disease index (OSDI), tear film break-up time (BUT), and score of corneal fluorescein staining (SCFS). They worsened significantly at 1w post-operation and then gradually improved: OSDI and BUT showed obvious improvement in 1 m post-operation (SMD =  - 0.58, 95%CI = [- 1.04, - 0.13]; SMD = 0.42, 95%CI = [0.06, 0.78]); SCFS was restored to preoperative levels in 3 m after surgery (SMD =  - 0.54, 95%CI = [- 1.16, 0.07]). Another parameter, Schirmer test without anesthesia (SIT), presented transient increase at 1w post-operation (SMD = 0.87, 95%CI = [0.27, 1.47]) and presented a relatively stable improvement after 1 m post-operation (SMD = 0.52, 95%CI = [0.16, 0.89]). All parameters in amniotic membrane graft (AMT) showed better improvement in early stage and they showed non-inferior improvements in the long term compared with conjunctival autograft (CAG). Limbal-conjunctival autograft (LCAG) made excellent improvement to OS in the long term while pterygium excision (PE) showed the worst OS. The type of pterygium (primary and secondary), diabetes mellitus (DM) status, and fixation method had certain effects on the results.

CONCLUSIONS

OS of pterygium is deteriorated at 1w post-operation then gradually improved to preoperative levels after 1 m post-operation. Among various surgery techniques, LCAG had the best improvement to OS which especially displayed in the long-term outcomes.

The Multifold Etiologies of Limbal Stem Cell Deficiency: A Comprehensive Review on the Etiologies and Additional Treatment Options for Limbal Stem Cell Deficiency

Given the various ocular manifestations of limbal stem cell insufficiency, an awareness of the genetic, acquired, and immunological causes and associated additional treatments of limbal stem cell deficiency (LSCD) is essential for providers. We performed a comprehensive review of the literature on the various etiologies and specific therapies for LSCD. The resources utilized in this review included Medline (PubMed), Embase, and Google Scholar. All English-language articles and case reports published from November 1986 through to October 2022 were reviewed in this study. There were collectively 99 articles on these topics. No other exclusion criteria were applied. Depending on the etiology, ocular manifestations of limbal stem cell deficiency range from dry eye syndrome and redness to more severe outcomes, including corneal ulceration, ocular surface failure, and vision loss. Identifying the source of damage for LSCD is critical in the treatment process, given that therapy may extend beyond the scope of the standard protocol, including artificial tears, refractive surgery, and allogeneic stem cell transplants. This comprehensive review of the literature demonstrates the various genetic, acquired, and immunological causes of LSCD and the spectrum of supplemental therapies available.

Comparison of vitamin D levels between patients with pterygium and healthy subjects

PURPOSE

The purpose of this study was to compare vitamin D (VD) deficiency frequency among patients with pterygium to that of healthy subjects and to investigate the VD deficiency among patients with pterygium.

METHODS

One-hundred eight pterygium patients and 94 healthy subjects were included in the study. Blood samples were collected from groups during the same time interval and the samples were saved. Serum 25-hydroxyvitamin D (25(OH)D) and parathormone (PTH) levels were measured and analyzed.

RESULTS

The pterygium group consisted of 57 female and 51 male patients, while the control group consisted of 47 female and 47 male patients. The mean age, sex and mean BMI were similar in the two groups (p > 0.05). The percentage of time that individuals spent outdoors was higher in the pterygium group (p = 0.02). The percentage of VD deficiency was 83.3% in the pterygium group and 61.7% in the control group (p = 0.001). There was a positive correlation between VD and time spent outdoors (p < 0.05).

CONCLUSIONS

VD deficiency can play a role in pterygium etiopathogenesis. Wide population-based studies in different regions are needed to evaluate this result.

MiR-199a-3p/5p participated in TGF-β and EGF induced EMT by targeting DUSP5/MAP3K11 in pterygium

Background

Recently, it has been reported that miRNA is involved in pterygium, however the exact underlying mechanism in pterygium is unrevealed and require further investigation.

Methods

The differential expression of miRNA in pterygium was profiled using microarray and validated with quantitative real-time polymerase chain reaction (qRT-PCR). Human conjunctival epithelial cells (HCEs) were cultured and treated with transforming growth factor β (TGF-β) and epidermal growth factor (EGF) and transfected with miR-199a-3p/5p mimic and inhibitor. Markers of epithelial-mesenchymal transition (EMT) in HCEs were detected using western blot and immunohistochemistry. Cell migration ability was determined using wound healing and transwell assay, while apoptosis was determined by flow cytometry. The target genes of miR-199a were confirmed by the dual-luciferase reporter assay.

Results

TGF-β and EGF could induced EMT in HCEs and increase miR-199a-3p/5p but suppress target genes, DUSP5 and MAP3K11. With the occurrence of EMT, cell migration ability was enhanced, and apoptosis was impeded. Promoting miR-199a-3p/5p expression could induce EMT in HCEs without TGF-β and EGF, while suppressing miR-199a-3p/5p could inhibit EMT in TGF-β and EGF induced HCEs. In a word, TGF-β and EGF induced EMT could be regulated with miR-199a-3p/5p-DUSP5/MAP3K11 axes. The validated results in tissues showed that, compared with control conjunctival tissues, miR-199a-3p/5p were more overexpressed in pterygium, while DUSP5/MAP3K11 were lower expressed. In addition, bioinformatics analysis indicated the miR-199a-3p/5p-DUSP5/MAP3K11 was belong to MAPK signalling pathway.

Conclusions

TGF-β and EGF induce EMT of HCEs through miR-199a-3p/5p-DUSP5/MAP3K11 axes, which explains the pathogenesis of EMT in pterygium and may provide new targets for pterygium prevention and therapy.

Tear Film Instability and Meibomian Gland Dysfunction Correlate with the Pterygium Size and Thickness Pre- and Postexcision in Patients with Pterygium

Purpose

This study aimed to evaluate the effects of excision on dry eye and meibomian gland dysfunction (MGD) in individuals with pterygium, before and after surgery. It also aimed to investigate how these effects correlate with the size and thickness of the pterygium.

Subjects and Methods

63 eyes from 63 patients with primary nasal pterygium and 45 eyes from 45 healthy volunteers without ocular pathologies were enrolled in this study. 63 eyes from 63 patients underwent pterygium surgery. ImageJ software was used to calculate the pterygium size based on images of the anterior segments. Anterior segment spectral domain optical coherence tomography (SD-OCT) was performed preoperatively to measure the thickness of the pterygium 1 mm anterior to the nasal scleral spur. The ocular surface disease index (OSDI), Schirmer I Test (SIT), and MGD grade were used to evaluate the eyes, and the eyes were imaged using the noninvasive keratograph average tear film breakup time (NIBUTav), tear meniscus height (TMH), meiboscore, and lipid layer grading tools of the Oculus® Keratograph 5M, preoperatively and at 1, 3, and 6 months postoperatively.

Results

The OSDI, NIBUTav, lid margin abnormality, meiboscore, and lipid layer grading values differed significantly in the pterygium patients in comparison with the controls (p < 0.01 for all scores). However, the SIT and TMH values were unchanged between the two groups (all p > 0.05). Multivariate regression analysis demonstrated that the NIBUTav, meiboscore, and lipid layer grading score was significantly correlated with the pterygium parameters, such as size and thickness. The postoperative OSDI, NIBUTav, lid margin abnormality, and lipid layer grading values improved significantly (p < 0.05 for all scores). The SIT, TMH, and meiboscore results did not differ significantly between the pre- and postoperative values (p > 0.05). Among the conventional and automated indexes, at 1 month postoperatively, SIT and TMH were significantly correlated with the pterygium parameters, but no correlation was observed at 3 and 6 months postoperatively. The OSDI, NIBUTav, meiboscore, and lipid layer grading values at 1, 3, and 6 months postoperatively were significantly correlated with the pterygium parameters.

Conclusion

Abnormal tear film and meibomian gland (MG) function improved following pterygium excision in the patients with primary pterygium, which was associated with uncomfortable ocular symptoms. Pterygium parameters, such as size and thickness, correlated with the dry eye and MGD indexes in patients pre- and postoperatively, potentially offering a novel strategy for clinical implementation of pterygium excision surgery.

Comparative Assessment of Tear Function Tests, Tear Osmolarity, and Conjunctival Impression Cytology between Patients with Pterygium and Healthy Eyes

Purpose:

To compare histologic abnormalities of tear film and tear osmolarity between normal eyes and eyes with pterygium.

Methods:

This was a prospective, hospital-based, case–control study involving 95 patients (65 men, 30 women) with unilateral pterygium. The tear meniscus height (TMH), Schirmer's test-1 (SCH-1) score, Rose Bengal staining (RBS) score, tear film breakup time (TBUT), tear osmolarity (TO), and conjunctival impression cytology (CIC) were assessed in both eyes. The Chi-square and Student's t-tests were used to compare the results between the two groups. P values <0.05 were considered statistically significant.

Results:

The mean patient age was 50.9 years, with the largest age group being the 45–55 year-old bracket across both genders. Most patients (82.1%) had nasal pterygium, and 80% were involved in outside activities. The mean assessment values in the case and control groups were as follows: TMH, 0.21 vs. 0.24 mm; SCH-1, 13.2 vs. 17.8 mm; RBS, 4.38 vs. 2.51 points; TBUT, 8.7 vs. 13.2 seconds; TO, 306 vs. 299 mOsm/L (P < 0.001 in all cases). The proportions of abnormal assessment values in the case and control groups were as follows: TMH, 82.1% vs. 3.16%; SCH-1, 20% vs. 2.1%; RBS, 30.53% vs. 4.22%; TBUT, 61.05% vs. 6.3%; TO, 10.52% vs. 1.05%; CIC, 33.7% vs. 7.37% (P < 0.05 for all comparisons).

Conclusion:

This study showed that the quantity and quality of tear film, as well as the number of goblet cells, decreased, but the tear osmolarity increased in eyes with pterygium. Furthermore, the TMH, RBS results, TBUT, and CIC have more precise state of the patient's tear condition with the disease of the pterygium.

A novel role for CRIM1 in the corneal response to UV and pterygium development

Pterygium is a pathological proliferative condition of the ocular surface, characterised by formation of a highly vascularised, fibrous tissue arising from the limbus that invades the central cornea leading to visual disturbance and, if untreated, blindness. Whilst chronic ultraviolet (UV) light exposure plays a major role in its pathogenesis, higher susceptibility to pterygium is observed in some families, suggesting a genetic component. In this study, a Northern Irish family affected by pterygium but reporting little direct exposure to UV was identified carrying a missense variant in CRIM1 NM_016441.2: c.1235 A > C (H412P) through whole-exome sequencing and subsequent analysis. CRIM1 is expressed in the developing eye, adult cornea and conjunctiva, having a role in cell differentiation and migration but also in angiogenesis, all processes involved in pterygium formation. We demonstrate elevated CRIM1 expression in pterygium tissue from additional individual Northern Irish patients compared to unaffected conjunctival controls. UV irradiation of HCE-S cells resulted in an increase in ERK phosphorylation and CRIM1 expression, the latter further elevated by the addition of the MEK1/2 inhibitor, U0126. Conversely, siRNA knockdown of CRIM1 led to decreased UV-induced ERK phosphorylation and increased BCL2 expression. Transient expression of the mutant H412P CRIM1 in corneal epithelial HCE-S cells showed that, unlike wild-type CRIM1, it was unable to reduce the cell proliferation, increased ERK phosphorylation and apoptosis induced through a decrease of BCL2 expression levels. We propose here a series of intracellular events where CRIM1 regulation of the ERK pathway prevents UV-induced cell proliferation and may play an important role in the in the pathogenesis of pterygium.

Evaluation of meibomian gland and tear film changes in patients with pterygium

Background:

Recent studies have demonstrated that pterygium has a close relationship with dry eye disease. This study is to determine abnormalities in meibomian gland and tear function in patients with pterygium and to assess the relationship between the variables.

Materials and Methods:

Forty eyes from forty patients with primary nasal pterygium and forty eyes from forty volunteers without ocular pathologies were enrolled in this study. Ocular surface disease index scores, meibomian gland expression scores, lid margin abnormality scores, meiboscore, tear film breakup time (BUT), Schirmer test (SIT) value, and the lower tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus area (TMA) using Fourier domain optical coherence were performed. Analysis of variance was applied for intergroup comparisons. A statistical significance level of P < 0.05 was considered.

Results:

Ocular symptom scores, BUT scores, lid margin abnormality, meibomian gland expression, and meiboscore were significantly higher in pterygium patients than in controls (P < 0.01 for all scores). However, the SIT scores, the lower TMH, TMD, and TMA values did not revealed a significant difference between two groups (all P > 0.05). Multivariate regression analysis demonstrated that meiboscore significantly correlated with ocular symptom scores, BUT, lid margin abnormality scores, and meibomian gland expression scores.

Conclusions:

Meibomian gland function may be altered in pterygium patients, which is associated with uncomfortable ocular symptoms. Being aware of meibomian gland changes seems essential to understand the complex relationship among pterygium, tear film functions, and ocular surface changes.

Tailored corneo-conjunctival autografting in primary and secondary pterygium surgery

PURPOSE

To describe the outcomes of a novel technique for pterygium removal: tailored corneo-conjunctival autograft, which offers the advantages of better postoperative cosmetic outcomes and recurrence prevention.

METHODS

This retrospective interventional noncomparative study included 420 eyes in 370 patients (ages 25-60 years) (127 women, 243 men). We divided the patients into 2 groups. The first group included 348 primary pterygium; the second group included 72 recurrent pterygium. All underwent the same type of corneo-conjunctival autograft surgery from April 2009 to March 2014. The average follow-up period was 12 months. The main outcome measures were to assess pain after surgery, conjunctival healing, cosmetic appearance, and pterygium recurrence at the end of follow-up.

RESULTS

In both groups, the graft donor site healed promptly without excessive scarring. No patient complained of pain during first week after surgery, except for mild discomfort. No major complications were observed such as infection or graft necrosis. In the first group, 2 patients had graft retraction towards the nasal side and were successfully managed conservatively. One patient had Tenon granuloma, which was removed surgically. Recurrence during the follow-up period was seen in one patient (0.2%). In the second group, no recurrent pterygium cases were observed.

CONCLUSIONS

The proposed type of corneo-conjunctival autograft offers the advantage of better postoperative cosmetic outcomes. This new technique is effective for surgical management of both primary and recurrent pterygium and preventing its recurrences.

Aberrant expression of genes and proteins in pterygium and their implications in the pathogenesis

Pterygium is a common ocular surface disease induced by a variety of factors. The exact pathogenesis of pterygium remains unclear. Numbers of genes and proteins are discovered in pterygium and they function differently in the occurrence and development of this disease. We searched the Web of Science and PubMed throughout history for literatures about the subject. The keywords we used contain pterygium, gene, protein, angiogenesis, fibrosis, proliferation, inflammation, pathogenesis and therapy. In this review, we summarize the aberrant expression of a range of genes and proteins in pterygium compared with normal conjunctiva or cornea, including growth factors, matrix metalloproteinases and tissue inhibitors of metalloproteinases, interleukins, tumor suppressor genes, proliferation related proteins, apoptosis related proteins, cell adhesion molecules, extracellular matrix proteins, heat shock proteins and tight junction proteins. We illustrate their possible mechanisms in the pathogenesis of pterygium as well as the related intervention based on them for pterygium therapy.

Curcuma longa Is Able to Induce Apoptotic Cell Death of Pterygium-Derived Human Keratinocytes

Pterygium is a relatively common eye disease that can display an aggressive clinical behaviour. To evaluate the in vitro effects of Curcuma longa on human pterygium-derived keratinocytes, specimens of pterygium from 20 patients undergoing pterygium surgical excision were collected. Pterygium explants were put into culture and derived keratinocytes were treated with an alcoholic extract of 1.3% Curcuma longa in 0.001% Benzalkonium Chloride for 3, 6, and 24 h. Cultured cells were examined for CAM5.2 (anti-cytokeratin antibody) and CD140 (anti-fibroblast transmembrane glycoprotein antibody) expression between 3th and 16th passage to assess cell homogeneity. TUNEL technique and Annexin-V/PI staining in flow cytometry were used to detect keratinocyte apoptosis. We showed that Curcuma longa exerts a proapoptotic effect on pterygium-derived keratinocytes already after 3 h treatment. Moreover, after 24 h treatment, Curcuma longa induces a significant increase in TUNEL as well as Annexin-V/PI positive cells in comparison to untreated samples. Our study confirms previous observations highlighting the expression, in pterygium keratinocytes, of nuclear VEGF and gives evidence for the first time to the expression of nuclear and cytoplasmic VEGF-R1. All in all, these findings suggest that Curcuma longa could have some therapeutic potential in the treatment and prevention of human pterygium.