Prevention of pterygium recurrence by postoperative single-dose β-irradiation: a prospective randomized clinical double-blind trial

Development of a Relative Dosimetric System for Calibration of 32P Eye Applicators Using Radiochromic Films

Introduction

Beta irradiation after bare scleral surgery of primary pterygium is an effective and safe treatment, which reduces the risk of local recurrence.

Purpose

Obtaining the reference dose rate for a radioactive applicator consisting of a plate as a 32P absorber, a steel window and a steel capsule.

Methods

Relative dosimetry and dose profile were measured using two types of radiochromic films, HD-810 and EBT1, for the 32P applicator and were compared with Monte Carlo simulation data. Dose uniformity in the 32P applicator was obtained with radiochromic HD-810 film.

Results

The measurement depth dose distribution data at distances up to 3.8 mm were compared with calculation data, and the values were not found to differ statistically. Depth dose distribution with a large dose gradient was determined and the dose rate data obtained 0.0053 ± 9.9% in unit of Gy/s.mCi at a 0.1 mm depth distance. Practical results indicated that the dose nonuniformity and the maximum symmetrical for the 32P applicator were 11.5% and 9.2%, respectively.

Conclusions

Our experiments show that the use of the radiochromic film to perform the relative dosimetric checks is feasible and the activity value with acceptable error can be determined through this indirect method.

A New Approach: Determination of the Safe Surgical Margin in Pterygium Surgery

PURPOSE

In this retrospective study, we aimed to determine the safe surgical limit for excision of pterygium tissue. Therefore, we aimed to prevent excessive or incomplete normal conjunctival tissue excision during surgery in the coming years.

METHODS

Autografted pterygium surgery was performed between January 2015 and April 2016, and the excised pterygium tissue was examined histopathologically. The files of 44 patients, who had not previously undergone any ocular surgery, who did not have an inflammatory disease and who continued to be checked for at least 1 year, were retrospectively examined. The distance (P-DSEM) from the excised pterygium tissue to the surgical excision margin was measured by a pathologist. Postoperative recurrence rates were evaluated according to this value. In this way, the clean surgical margin was determined.

RESULTS

The mean age of the participants was 44.77 ± 12.70, and the mean follow-up time was 55.61 ± 16.38 months. Recurrence developed in 5 out of 44 patients (11.4%). The average recurrence duration was 51 ± 13.87 days. Distance to the average surgical margin was 3.88 ± 0.91 mm. The surgical distances of 5 patients with recurrence were 2, 2.5, 2, 3, and 3 mm, respectively. It was determined that recurrence was less as the distance (P-DSEM) from the tissue to the surgical excision margin increased (p = 0.001).

CONCLUSIONS

We found that the recurrence rate in pterygium surgery was linked to the clean surgical margin. When planning pterygium surgery, we believe that determining the amount of tissue to be excised before surgery will reduce recurrence rates.

How to minimize pterygium recurrence rates: clinical perspectives

The main treatment for pterygium is surgical removal. However, pterygium surgery is concerned with high rates of postoperative recurrence. Predicting factors of recurrence are not fully understood, yet, but they probably depend on a multitude of patient-related, clinical, and/or surgical factors. Several adjuvant treatments have been proposed to reduce postoperative pterygium recurrence, including different antimetabolites, antiangiogenetic factors, and radiation therapy. The purpose of this review is to collect the current evidence regarding application and limits of different therapeutic approaches for preventing postoperative recurrence of pterygium, giving insights and perspectives for better management of this disease. In the light of the current evidence, pterygium surgery cannot disregard wound coverage with conjunctival autografting or rotational flap combined with adjuvant treatments. The rotational flap technique is associated with shorter surgical time rates and prevents graft displacement and necrosis, given its vascular pedicle. Amniotic membrane may still be reserved in case of great conjunctival defects or insufficient conjunctiva. Repeated subconjunctival antivascular endothelial growth factor injections can be considered as an effective and safe adjuvant treatment. Moreover, management of postoperative pain is crucial. Innovative treatment strategies will probably target different molecular pathways, considering recent findings regarding pterygium pathogenesis, to improve better understanding and develop universally shared guidelines. Great importance shall be dedicated to the identification of novel molecular biomarkers and favoring factors of recurrence, in order to achieve a customized surgical treatment for each patient and obtain maximal reduction of postoperative recurrence.

Anti-fibrotic, anti-VEGF or radiotherapy treatments as adjuvants for pterygium excision: a systematic review and network meta-analysis

Background

Anti-fibrotic, anti-VEGF (vascular endothelial growth factor) medications, or radiotherapy, as adjuvant for pterygium surgical procedure, has been suggested for reducing recurrence, but difficulties may be experienced in deciding which treatment to use. The purpose of this study was to compare the efficacies of these different adjuvants for preventing recurrence following pterygium surgery.

Methods

We conducted a systematic review to identify randomized controlled trials of patients with primary or recurrent pterygium who received anti-fibrotic, anti-VEGF medication, or radiotherapy as adjuvants in combination with surgical procedure. The surgical procedure contained bare sclera technique or petrygium excision combination with tissue grafting. The primary outcome of this study was recurrence. Direct-comparison and Bayesian network meta-analyses were performed to assess direct and indirect evidence of efficacy.

Results

We obtained data from 34 randomized controlled trials, representing a total of 2483 patients. Adjuvants included bevacizumab, 5-FU (5-fluorouracil), MMC (mitomycin C), and β-RT (beta-radiotherapy). Compared with placebo, we found distinguishable improvement in recurrence with bevacizumab (odds ratio [OR] 0.38, 95% confidence interval [CI] 0.18–0.80), MMC (0.12, 95% CI 0.06–0.21), and β-RT (0.17, 95% CI 0.04–0.69), but not with 5-FU (0.41, 95% CI 0.12–1.39). MMC significantly reduced recurrence when compared to bevacizumab (0.31, 95% CI 0.13–0.77) and 5-FU (0.28, 95% CI 0.08–0.99). The probability of having the most recurrences after excision was lowest for MMC, followed by bevacizumab and β-RT. Similar results were found in subgroup analyses, including for primary pterygium, and the patients receiving bare sclera technique or conjunctival autograft.

Conclusions

Adjuvants such as MMC, bevacizumab, and β-RT could effectively prevent recurrence following pterygium excision. However, their efficacy and acceptability require further clarification in future randomized controlled trials.

Electronic supplementary material

The online version of this article (10.1186/s12886-017-0601-5) contains supplementary material, which is available to authorized users.

5-Fluorouracil vs avastin as adjunct to conjunctival autograft in the surgical treatment of pterygium

BACKGROUND

The use of adjunct antimetabolite therapy along with conjunctiva autograft has been shown to be effective in preventing pterygium recurrence. There has however been fewer reports on the effect of anti-vascular endothelial growth factor on pterygium recurrence.

OBJECTIVE

To compare 5-fluorouracil with conjunctival autograft with bevacizumab (avastin) used along with autograft in the surgical treatment of pterygium.

METHODS

A randomized controlled prospective study of outcome of pterygium treatment using 5-fluorouracil with conjunctiva autograft as adjuvant treatment compared avastin with conjunctiva autograft.

RESULTS

A total of 70 eyes of 70 patients were recruited into the study with a mean age of 51.49 (±14.36) years. Thirty-five patients each were randomized into the 5-fluorouracil treatment group and into the avastin treatment group respectively. The mean follow-up was 18.35 months (18.44 for the 5-FU and 18.26 for the avastin group). Post operative, pterygium recurrence was observed in 1/27 (3.7%) eyes treated with 5-fluorouracil and 1/26 (3.9%) eyes of the avastin group. Both recurrences were observed at 1 year of follow-up and they were both female patients aged 46 and 52 years, respectively.

CONCLUSIONS

Both 5-fluorouracil and avastin are comparably effective as adjunct to conjunctival autograft. However, cost, availability, and convenience are other considerations with use of avastin.

[Radiotherapy indications for non-malignant diseases in 2014]

This review updates the radiotherapy indications for non-malignant diseases, except those treated by radiosurgery. Since the last 2005 review, there have been no major changes in the indications: the prevention of heteropic bone formation and keloids remain classical indications, while the treatment of macular degeneration or the prevention of coronary restenosis are now past history. Nevertheless, the radiation treatment for benign diseases should have the same criteria as for malignant diseases: information of the patient on risks, benefits and treatment quality.

Low-dose strontium-90 irradiation is effective in preventing the recurrence of pterygia: a ten-year study

Background

To study the long-term effects of low-dosage strontium-90 (Sr90) irradiation on the recurrence of pterygium.

Methodology/Principal Findings

One hundred twenty eyes from 104 patients with primary or recurrent pterygia were treated with surgery followed by Sr90 irradiation. In brief, starting on the sixth day after surgery, patients were treated with irradiation three times every other day at a total combined dosage of 2000 cGy to 3000 cGy. Corneal topography was used to evaluate ocular surface regularity before and after treatment. Patient follow-up was performed 2 days, 5 days, 2 weeks, 1 month, 3 months, 1 year, 5 years, and 10 years after surgery. Recurrence of pterygium was not observed in any of the patients in this study. Obvious cataract progression was observed in 6 eyes, which may be due to aging. During follow-up studies, only one eye was reported with dryness and foreign-body sensation. Significant pterygium-induced astigmatism was observed in corneal topography, which decreased after surgery.

Conclusions/Significance

Sr90 irradiation is effective in preventing the recurrence of primary and recurrent pterygia. We recommend delivering a total combined dosage of 2000 cGy to 3000 cGy of Sr90 irradiation administered in three batches every other day starting from the sixth day after surgery. Surgery is important in the rapid recovery of the cornea from pterygium-induced astigmatism.

Reirradiation of spinal column metastases: comparison of several treatment techniques and dosimetric validation for the use of VMAT

BACKGROUND

For reirradiation of spinal column metastases, intensity-modulated radiation therapy (IMRT) reduces the dose to the spinal cord, while allowing longer treatment times. We analyzed the potential of volumetric modulated arc therapy (VMAT) to reduce treatment time and number of monitor units (MU).

PATIENTS AND METHODS

In CT datasets of 9 patients with spinal column metastases, the planned target volume (PTV) encompassed the macroscopic tumor including the spinal cord or medullary cone, respectively. The prescribed dose for the target was 40 Gy, but median spinal cord dose was intended to be < 26 Gy. We compared a posterior (3D-PA) static field technique, a two-field wedge technique (3D-wedge) and 5-/7-beam IMRT with VMAT. Conformity index (CI), homogeneity index (HI40), dose volume histogram (DVH) parameters, treatments delivery time (T), and MU were analyzed. Dosimetry was validated with EDR2-film/ionization chambers.

RESULTS

PTV coverage was insufficient for 3D-conformal radiotherapy (3D-CRT) when spinal cord tolerance was respected. The IMRT approach provided excellent results but has the longest treatment time. VMAT produced dose distributions similar to IMRT with shorter treatment times (VMAT: mean 4:49 min; IMRT: mean 6:50 min) and fewer MU (VMAT: 785; IMRT: 860). Reduced conformity and increased homogeneity for VMAT when compared to IMRT were observed. An absolute deviation between measured and calculated dose of +0.70 ± 3.69% was recorded. γ-Index analysis showed an agreement of 91.33 ± 3.53% for the 5%/5 mm criteria.

CONCLUSION

For this paradigm, VMAT produces high quality treatment plans with homogeneity/conformity similar to static IMRT, shorter treatment times, and fewer MU. Verification measurements showed good agreement between calculation and delivered dose, leading to clinical implementation.

[Pterygium surgery. Complication following adjuvant radiotherapy]

Scleromalacia is a rare but serious complication following excision of an atypical pterygium and postoperative radiation which needs immediate action and treatment. In this case report we describe a successful method for treating this condition with amniotic membrane transplantation. Despite severe blepharoconjunctivitis the patient is now free of recurrence of pterygium for 3 years supporting the use of amnion membranes for covering scleromalacia in inflammatory conditions.

[Limbal-conjunctival autograft in pterygium surgery]

INTRODUCTION

The aim of this study was to estimate the efficacy of limbal-conjunctival autograft in the treatment of pterygium.

MATERIAL AND METHODS

We conducted a retrospective study including 15 patients (16 eyes) operated on for pterygium by limbal-conjunctival autograft. The examination included the search for risk factors and visual acuity, as well as corneal astigmatism and pterygium measurement. The follow-up included an examination at day 8, 1 month, and 3 months and assessed the integration of the transplant on the eye's surface, the aesthetic aspect, and recurrence. We describe the patients' characteristics, visual acuity, and astigmatism before and after surgery.

RESULTS

The mean age of the patients was 56 years (range, 31-81 years). Before surgery, irritative signs and astigmatism, were found in 37% and impaired visual acuity in 81%. The mean duration of the follow-up after surgery was 19 months. Visual acuity and astigmatism improved in 56% of our patients. All transplants and harvest sites had a satisfactory macroscopic aspect. However, one patient suffered from a corneal invasion by fibrovascular tissue, 7 months postoperatively, which remained stable at the end of follow-up.

DISCUSSION/CONCLUSION

In our study, the limbal-conjunctival autograft was a safe and effective surgical treatment with a very low recurrence rate at long-term follow-up.

Dose-effect relationships for recurrence of keloid and pterygium after surgery and radiotherapy

PURPOSE

To show radiation dose-response relationships for recurrence of keloid and pterygium after radiotherapy following surgery.

METHODS AND MATERIALS

Using PubMed, we performed a retrospective review of articles reporting incidences and/or dose-response relationships for recurrence of keloid and pterygium after radiotherapy following surgery. The irradiation regimens identified were normalized by use of the linear-quadratic model; biologically effective doses (BEDs) were calculated.

RESULTS

For keloid recurrence after radiotherapy following keloid removal, with either teletherapy or brachytherapy, the recurrence rate after having delivered a BED greater than 30 Gy is less than 10%. For pterygium recurrence after bare sclera surgery and (90)Sr beta-irradiation, a BED of about 30 Gy seems to be sufficient also to reduce the recurrence rate to less than 10%.

CONCLUSIONS

Most of the doses in the radiotherapy schemes used for prevention of keloid recurrence after surgery are too low. In contrast, the doses applied in most regimens to prevent pterygium recurrence are too high. A scheme with a BED of 30 to 40 Gy seems to be sufficient to prevent recurrences of keloid as well as pterygium.

Use of 'sham' radiotherapy in randomized clinical trials

The objective of this systematic review was to identify quality trials that use sham radiotherapy in their design and review them to determine its potential value. The Cochrane Library, Pubmed and a Reference Search served as data sources. Trials were included if they met a minimum quality score of 3 on a validated assessment instrument (which assesses randomization, control and blinding) and if they compared sham radiotherapy to active treatment. External beam therapy and brachytherapy trials were considered. Twenty-six trials were identified, collectively including 2663 participants in the period of 1970-2004. All the trials studied the value of radiotherapy for treatment or prevention of benign diseases, including multiple sclerosis, coronary artery restenosis, age-related macular degeneration and Graves' ophthalmopathy. There were no trials relating to the use of radiotherapy in the treatment of malignancy. This review showed that it is possible to carry out sham radiotherapy with due regard for ethical concerns, with effective blinding and high levels of patient acceptance. Large sample sizes with multicentre trial designs were achievable. Although the statistical philosophy for using sham radiotherapy in trials is legitimate, it is no longer routinely used.

The use of hyperbaric oxygen therapy in ophthalmology

Hyperbaric oxygen therapy is a primary or adjuvant therapeutic method used in treatment of various acute or chronic disorders. Currently, eye diseases are among the off-label use of hyperbaric oxygen. However, there is an increasing body of evidence showing its safety and efficacy in retinal artery occlusion, cystoid macular edema secondary to retinal vein occlusion, scleral thinning and necrosis faced after pterygium surgery, orbital rhino-cerebral mucormycosis, nonhealing corneal edema, and anterior segment ischemia. Its potential to treat some blinding disease has also been pointed out in recent studies. This article constitutes an up-to-date summary of knowledge and therapeutic use of hyperbaric oxygen, and aims to contribute understanding of current and potential use of hyperbaric oxygen therapy in ophthalmology.

Hot particle dosimetry and radiobiology--past and present

Small high-activity radioactive particles of nominal diameter ranging from approximately 1 mm down to several microm have been a radiological concern over the last 30 years in and around European and American nuclear reactor facilities. These particles have often been referred to as 'hot particles'. The 'hot particle problem' came into prominent concern in the late 1960s. The potential carcinogenic effects in lungs as the result of irradiation by discrete small particles containing alpha-emitting radionuclides, particularly (239)Pu, were claimed by some to be several orders of magnitude greater than those produced by uniform irradiation to the same mean dose. The phrase 'hot particle problem' was subsequently used to refer to the difficulty of predicting health effects for all microscopic radioactive sources. The difficulty arose because of the paucity of comparative human, animal or cell studies using radioactive particles, and the lack of validated measurement or calculational techniques for dose estimation for non-uniform exposures. Experience was largely restricted to uniform, large-area/volume exposures. The concern regarding cancer induction was extended to deterministic effects when the ICRP in 1977 failed to give adequate dose limits for dealing with 'hot particle' exposures of the skin. Since 1980, considerable efforts have been made to clarify and solve the dosimetric and radiobiological issues related to the health effects of 'hot particle' exposures. The general recommendations of the ICRP in 1991 used the latest radiobiological data to provide skin dose limits which are applicable to 'hot particle' exposures. More recently the NCRP has extended considerations to other organs. This progress is reviewed and applied to the specific case of the recent evaluation of potential health effects of Dounreay fuel fragments commissioned by the Scottish Environment Protection Agency (SEPA). Analyses of possible doses and risks in this case indicate that the principal concern following skin contact, ingestion or inhalation is the possibility of localised ulceration of skin or of the mucosal lining of the colon or extra-thoracic airways.

Current concepts and techniques in pterygium treatment

PURPOSE OF REVIEW

Pterygium is a common ocular disorder in many parts of the world. At present, there is a wide variety of surgical methods but very few clinical guidelines on the optimal treatment of primary or recurrent pterygium. The purpose of this review is to summarize the more recent and relevant studies on pterygium treatment.

RECENT FINDINGS

The primary aim is to excise the pterygium and prevent its recurrence. As bare sclera excision is associated with a high recurrence rate, pterygium excision is often combined with conjunctival autograft, mitomycin C, beta-irradiation or other adjunctive therapies to reduce recurrence rates. There is currently, however, no consensus regarding the ideal treatment for the disease. Comparability between studies is also hampered by the various definitions of pterygium recurrence.

SUMMARY

This article reviews the current concepts and techniques used for the treatment of pterygium. Conjunctival autografting and mitomycin C application are the most commonly used methods for preventing recurrences. The use of mitomycin C and beta-irradiation should be used judiciously because of the potential long-term risk of sight-threatening complications. Additional clinical trials should be performed to evaluate the relative efficacies and long-term safety of the various treatment modalities.

La radiothérapie des affections bénignes : quelles indications huit ans plus tard ?

The authors present an update version of the indications for radiotherapy in the management of benign diseases. This is based on available randomized trials and recent international meetings. Validated indications remain the prevention of resected heterotopic bone ossifications, keloïds scars and pterygium and also treatment of arteriovenous malformations; the place of radiotherapy for malignant exophtalmia is more and more restricted. Randomized trials have demonstrated the efficacy of endobrachytherapy in the prevention of restenosis after angioplasty but the use of embedded stent has replaced this indication. Macular degeneration is no more an indication of radiotherapy. Quality requirements for radiotherapy are identical for benign or malignant indications.

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.