Meibomian Gland Dysfunction Associated With Periocular Radiotherapy

Ocular surface changes in patients who have undergone head and neck radiation therapy

PURPOSE

Dry eye syndrome (DES) is a familiar sequelae of radiation therapy (RT) for head and neck cancers (HNC). Ocular surface changes such as DES occur due to injury to the conjunctival epithelium, goblet cells, corneal surface, lacrimal glands, and meibomian glands. This study aimed at the evaluation and early detection of changes in ocular surface parameters in patients receiving RT for extraocular HNC.

METHODS

Forty-two eyes of 21 patients undergoing HNC RT were evaluated. Radiation technique and dose of radiation to the lens and eye were recorded. Subjects were evaluated for meibomian gland changes by meiboscore grading, ocular surface disease index (OSDI) questionnaire, Schirmer's test, tear film break-up time (TBUT), and slit-lamp examination before RT, immediately post RT, and 6 weeks post RT. A comparison of the ipsilateral eye on the irradiated side to the contralateral eye was done.

RESULTS

A significant reduction in TBUT was seen immediately post RT and 6 weeks post RT ( P < 0.001 and 0.008, respectively), with an increase in meiboscore at both visits ( P < 0.001). An OSDI score of >13 was seen in 23.80% of patients post RT, with a significant difference from baseline ( P < 0.001). On comparing ipsilateral and contralateral eye groups, a significant difference from baseline was seen in TBUT ( P < 0.001 and 0.033, respectively) and meiboscore ( P < 0.001 for both eyes). A significant change of >1 second in TBUT and >1.7 in meiboscore was seen with a mean dose of around 8 Gy to the lens.

CONCLUSION

All patients undergoing HNC RT should be followed up for ocular surface and meibomian gland changes. The contralateral eye should also be evaluated. Patients receiving lower doses to the ocular structures should also be kept under follow-up.

A comparative review of evaporative dry eye disease and meibomian gland dysfunction in dogs and humans

Dry eye disease is a complex ophthalmic disorder that consists of two main subtypes, aqueous deficient dry eye (ADDE) and evaporative dry eye disease (EDED). Due to the complex underlying physiology, human dry eye disease can be difficult to model in laboratory animal species. Thus, the identification and characterization of a spontaneous large animal model of dry eye disease is desirable. Dogs have been described as an ideal spontaneous model of ADDE due to the similar pathophysiology between dogs and humans. Recently, EDED and meibomian gland dysfunction (MGD) have been increasingly recognized and reported in dogs. These reports on EDED and MGD in dogs have identified similarities in pathophysiology, clinical presentations, and diagnostic parameters to humans with the comparable disorders. Additionally, the tests that are used to diagnose EDED and MGD in humans are more easily applicable to dogs than to laboratory species due to the comparable globe sizes between dogs and humans. The reported response of dogs to EDED and MGD therapies are similar to humans, suggesting that they would be a valuable preclinical model for the development of additional therapeutics. Further research and clinical awareness of EDED and MGD in dogs would increase their ability to be utilized as a preclinical model, improving the positive predictive value of therapeutics for EDED and MGD in both humans and dogs.

Alterations in meibomian glands in patients treated with intensity-modulated radiotherapy for head and neck cancer

Patients undergoing intensity-modulated radiotherapy (IMRT) for head and neck cancer may have increased incidence of dry eye disease and the exact mechanism is unclear. The present study aims to assess tear film and meibomian gland (MG) features in patients who received IMRT for head and neck cancer not involving the orbital area. Twenty-seven patients (64.7 ± 9.8 years) and 30 age-matched controls (61.4 ± 11.0 years) underwent a comprehensive dry eye work-up. Compared to the control group, the patients had more lid margin abnormalities, and worse meibum quality. The MG loss, calculated as (tarsal area-MG area)/tarsal area, was higher in the patient group in both the upper (53.0 ± 12.0% vs. 35.1 ± 10.3%, p < 0.001) and lower lids (69.5 ± 12.6% vs. 48.5 ± 12.5%, p < 0.001). In the patient group, more MG loss in the lower lids correlated with worse meibum quality (r = 0.445, p = 0.029). In contrast, there was no significant difference in aqueous tear production level, measured with Schirmer test. Patients treated with IMRT for head and neck cancer seemed to have comparable lacrimal gland function to the controls despite more dry eye symptoms. However, the patients had MG functional and morphological changes, which may present a higher risk for developing dry eye disease.

Eyelid blood vessel and meibomian gland changes in a sclerodermatous chronic GVHD mouse model

PURPOSE

To investigate pathological changes in blood vessels and meibomian glands (MGs) in the eyelids of sclerodermatous chronic graft-versus-host disease (cGVHD) model mice.

METHODS

We used an established major histocompatibility complex compatible, multiple minor histocompatibility antigen-mismatched sclerodermatous cGVHD mouse model. Blood vessels and MGs of eyelids from allogeneic bone marrow transplantation (allo-BMT) recipient mice and syngeneic bone marrow transplantation (syn-BMT) recipient mice were assessed by histopathology, immunohistochemistry and transmission electron microscopy. Peripheral blood samples from the recipients were examined by flow cytometry.

RESULTS

Allo-BMT samples showed dilating, tortuous and branching vessels and shrunk MGs in the eyelids; showed significantly higher expression of VEGFR2 (p = 0.029), CD133 (p = 0.016), GFP (p = 0.006), and α-SMA (p = 0.029) in the peripheral MG area; showed endothelial damage and activation, fibrotic change, and immune cell infiltration into MGs compared with syn-BMT samples. Fewer Ki-67⁺ cells were observed in allo- and syn-BMT samples than in wild-type samples (p = 0.030). Ultrastructural changes including endothelial injury and activation, fibroblast activation, granulocyte degranulation, immune cell infiltration into MGs, and necrosis, apoptosis of MG basal cells were found in allo-BMT samples compared with syn-BMT samples.

CONCLUSION

A series of our studies indicated that cGVHD can cause eyelid vessel and MGs changes, including endothelial injury and activation, neovascularization, early fibrotic changes, immune cell infiltration, MG basal cell necrosis and apoptosis, and resultant MG atrophy.

Ocular surface complications of local anticancer drugs for treatment of ocular tumors

Local chemotherapy is increasingly used, either in combination with surgery or as monotherapy, for management of ocular tumors. Yet many of the local chemotherapeutic agents used for ocular tumors are cytotoxic drugs that are frequently associated with toxicities in normal ocular tissues. Understanding and managing these side effects are important because they affect treatment tolerability, outcome and quality of vision. Herein, we review local anticancer drugs administered for the treatment of ocular tumors, with an emphasis on their toxicities to the ocular surface, adnexa and lacrimal drainage system. We provide the underlying mechanisms and management strategies for the ocular side effects. Recent innovations in anticancer immunotherapy and ocular drug delivery systems also are discussed as new potential therapeutic modalities for alleviation of side effects.

Ocular Complications After Radiation Therapy: An Observational Study

Aim of the Study

The study aims to quantify the incidence of ocular complications in patients irradiated on the head and neck area in our medical center, stratified by type of neoplasm and radiation dose received.

Materials and Methods

From an existing database of patients radio-treated in our center, we selected 25 patients irradiated in the 2011-2018 period. The patients had been treated for orbital lymphoma, nasopharyngeal carcinoma and cranial base meningioma. The selected patients received an ophthalmologic evaluation which included a complete ophthalmological and orthoptic assessment.

Results

Our results showed a significantly higher incidence of DES (dry eye syndrome) and corneal complications for eyes receiving a Dmax higher than 40 Gy, as well as for cataract incidence in eyes that had received a Dmax to the lens higher than 5 Gy. We found an overall thinning of the RNFL (retinal nerve fiber layer) in eyes that had received a Dmax higher than 50 Gy, as well as a greater MD (mean deviation) from normal visual field values.

Conclusion

In conclusion, we can say that the study confirms the presence of a correlation between the received radiation dose and the onset of eye complications, despite the small sample.

The role of meibography in ocular surface diagnostics: A review

The meibomian glands are lipid-secreting glands located in the tarsal plates, whose secretory products cover the tear film, thereby reducing evaporation as well as ensuring lubrication of the ocular surface. The meibomian glands can be visualized at different levels of magnification by infrared meibography, laser confocal microscopy, and optical coherence tomography. These imaging modalities have been subject to much research and progress in clinical practice and have shaped our current understanding of meibomian glands in health and disease. In this review, we explore the evolution of meibography over the past decades, the major contributions of various meibographic modalities, and discuss their clinical significance.

Dyslipidemia and Meibomian Gland Dysfunction: Utility of Lipidomics and Experimental Prospects with a Diet-Induced Obesity Mouse Model

Meibomian gland dysfunction (MGD) is the leading cause of dry eye disease and loss of ocular surface homeostasis. Increasingly, several observational clinical studies suggest that dyslipidemia (elevated blood cholesterol, triglyceride or lipoprotein levels) can initiate the development of MGD. However, conclusive evidence is lacking, and an experimental approach using a suitable model is necessary to interrogate the relationship between dyslipidemia and MGD. This systematic review discusses current knowledge on the associations between dyslipidemia and MGD. We briefly introduce a diet-induced obesity model where mice develop dyslipidemia, which can serve as a potential tool for investigating the effects of dyslipidemia on the meibomian gland. Finally, the utility of lipidomics to examine the link between dyslipidemia and MGD is considered.

Meibomian gland dropout rate as a method to assess meibomian gland morphologic changes during use of preservative-containing or preservative-free topical prostaglandin analogues

PURPOSE

To investigate the usefulness of meibomian gland (MG) dropout rate in the evaluation of MG morphological change associated with the use of prostaglandin for glaucoma treatment through the association between MG and the ocular surface parameters and medication duration and presence of preservative.

METHODS

This cross-sectional study was conducted on 88 eyes of 88 patients who were diagnosed with glaucoma and used only Tafluprost as treatment. The patients were divided into four "user" groups: 1) 23 patients used preservative-free (PF) Tafluprost for 6 months; 2) 21 patients used preservative-containing (PC) Tafluprost for 6 months; 3) 23 patients used PF-Tafluprost for 24 months; 4) 21 patients used PC-Tafluprost for 24 months. Ocular surface parameters and the MG condition, including MG dropout rate and meiboscale, were evaluated. Multiple regression was used to identify associations.

RESULTS

There were significant differences in age (p = 0.003), tear breakup time (p = 0.016), lid margin abnormality (p = 0.016), expressibility (p = 0.039), meiboscale (p<0.001), and MG dropout rate (p<0.001) among the 4 groups. MG dropout rate and meiboscale showed significant differences in all post hoc analyses, except for the comparison between the PF-Tafluprost and PC-Tafluprost 6-month user groups. Medication duration, preservative status, and meiboscale were significantly correlated with MG dropout rate (p<0.001, p = 0.024, p<0.001, respectively). In the 6-month user group, preservative status significantly correlated with MG dropout rate (p = 0.015). However, in the 24-month user group, meiboscale was the only parameter significantly associated with MG dropout rate (p<0.001).

CONCLUSION

MG dropout rate in patients using Tafluprost showed a significant correlation with medication duration and preservative status. This result indicates MG dropout rate reflects MG morphologic change associated with prostaglandin.

Meibography: A Japanese Perspective

Meibography allows observation of meibomian glands in an objective and repeatable manner. Original meibography systems were invasive and not readily adopted by ophthalmology clinics. The development of noncontact infrared meibography allowed the rapid and noninvasive observation of meibomian glands, and such systems have now been widely adopted for standard examinations in dry eye clinics. Noncontact meibography has also spurred research into meibomian glands and has been applied to evaluation of their structure and status in various ocular surface diseases. Although the images obtained by meibography are objective and repeatable, the interpretation of these images is subjective, with the relationship between image features and actual gland structure and composition remaining unclear. Additional clinical and basic research with regard to the interpretation of meibography images is thus necessary. Future improvements to meibography will likely provide new insights into the pathophysiology of meibomian gland diseases as well as enhance its contribution to the diagnosis and evaluation of treatments for such diseases.

Longitudinal analysis of meibomian gland dropout in patients with ocular graft-versus-host disease

PURPOSE

To evaluate morphological changes in meibomian glands (MGs) over 1 year in patients diagnosed with chronic ocular graft-versus-host disease (GVHD), and to determine the association between MG loss and ocular surface parameters in such patients.

METHODS

This retrospective, observational study included 37 patients diagnosed with ocular GVHD who were followed-up for at least 1 year in the ophthalmology department. All patients received treatment during the follow-up period. The Ocular Surface Disease Index (OSDI) score, tear breakup time (TBUT), corneal staining score, lid margin score, Schirmer test I value, and noncontact infrared meibography findings were evaluated at baseline and after 1 year of follow-up for ocular GVHD. Both eyes were included in the analyses.

RESULTS

OSDI (p = 0.0391), corneal fluorescein scores (p = 0.0352 and 0.0181 for the right and left eyes, respectively), and upper and lower eyelid meiboscores (right eye: p = 0.0039 and 0.0156, respectively: left eye: p = 0.0273 and 0.0156, respectively) were significantly higher at 1 year than at baseline. Infrared meibography showed MG loss in 18.9% of eyes, improvement in 5.4% of eyes, and no changes in 75.7% of eyes, respectively. The Schirmer value for the right eye negatively correlated with the upper eyelid meiboscore at 1 year (p = 0.0103, r = -0.46), whereas the corneal fluorescein score for the left eye positively correlated with both upper and lower eyelid meiboscores at 1 year (p = 0.0368, r = 0.40; p = 0.0387, r = 0.39, respectively).

CONCLUSIONS

Rapid and aggressive MG destruction may occur in patients with ocular GVHD. Further studies with larger patient samples and longer follow-up periods are mandatory to validate these conclusions.

Impact of Unilateral Orbital Radiotherapy on the Structure and Function of Bilateral Human Meibomian Gland

Background

Radiotherapy (RT) has widely been used to treat ocular tumors, yet the impact of orbital radiation to the meibomian gland has rarely been studied. Our study aims at evaluating the bilateral meibomian gland structure and function 12 months after unilateral orbital RT in patients with ocular tumors.

Methods

An observational case-control study. A total of 10 eyes 12 months after unilateral orbital RT, 10 contralateral eyes, and 10 normal controls were enrolled. Meibomian gland loss (MGL), lipid layer thickness (LLT), tear film breakup time (TBUT), Schirmer I test, and cornea fluorescein staining were measured. Ocular Surface Disease Index (OSDI) of the RT patients was assessed and compared with normal controls.

Results

The cumulative median radiotherapy dosage for the patients was 45 (range: 30, 70) Gy. The OSDI score of the patients was significantly greater than the normal controls (22.92 (range: 10.42, 37.50) vs 6.25 (range: 2.08, 10.42), p ≤ 0.001). Significant differences of upper MGL, lower MGL, LLT, and TBUT were found between the diseased eyes and normal controls (37.79% (range: 12.87, 92.41) vs 12.63% (range: 6.13, 42.34), p=0.007; 61.31% (range: 44.67, 87.98) vs 15.53% (range: 7.65, 45.13), p ≤ 0.001; 40 ICU (range: 23, 100) vs 81.5 ICU (range: 54, 100), p=0.007; 3.5 s (range: 2, 8) vs 6.5 s (range: 5, 10), p=0.002). The upper MGL and TBUT of the contralateral eyes were also considerably damaged compared with normal controls. Lower eyelid MGL and cornea staining score of the diseased eye were significantly correlated with radiation dosage (r = 0.913 and 0.680; p=0.001 and 0.044, respectively).

Conclusion

Orbital radiotherapy could cause significant damage to the meibomian gland structure and function, not only the diseased eyes but also the contralateral eyes.

Radiation dose constraints for organs at risk in neuro-oncology; the European Particle Therapy Network consensus

PURPOSE

For unbiased comparison of different radiation modalities and techniques, consensus on delineation of radiation sensitive organs at risk (OARs) and on their dose constraints is warranted. Following the publication of a digital, online atlas for OAR delineation in neuro-oncology by the same group, we assessed the brain OAR-dose constraints in a follow-up study.

METHODS

We performed a comprehensive search to identify the current papers on OAR dose constraints for normofractionated photon and particle therapy in PubMed, Ovid Medline, Cochrane Library, Embase and Web of Science. Moreover, the included articles' reference lists were cross-checked for potential studies that met the inclusion criteria. Consensus was reached among 20 radiation oncology experts in the field of neuro-oncology.

RESULTS

For the OARs published in the neuro-oncology literature, we summarized the available literature and recommended dose constraints associated with certain levels of normal tissue complication probability (NTCP) according to the recent ICRU recommendations. For those OARs with lacking or insufficient NTCP data, a proposal for effective and efficient data collection is given.

CONCLUSION

The use of the European Particle Therapy Network-consensus OAR dose constraints summarized in this article is recommended for the model-based approach comparing photon and proton beam irradiation as well as for prospective clinical trials including novel radiation techniques and/or modalities.