Impact of environmental adaptation on tear film assessments

Low-level light therapy and intense pulse light therapy in meibomian gland dysfunction. A systematic review and meta-analysis

BACKGROUND

Meibomian gland dysfunction (MGD) is a leading cause of dry eye disease, affecting over a third of the global population. This disease is associated with ocular discomfort, reduced visual quality, and quality of life. Novel treatments like Intense Pulse Light (IPL) therapy and Low-Level Light Therapy (LLLT) have been reported to be useful in refractory MGD treatment. However, no systematic review has explored the utility of combining these two therapies.

METHODS

Medline, Embase, and CENTRAL databases were searched for articles on LLLT + IPL therapy in MGD. A meta-analysis of single means was conducted to assess clinical endpoints.

RESULTS

Analysis of 12 studies showed that LLLT + IPL therapy in MGD patients led to a significant decrease in Ocular Surface Disease Index score (MD: -22.8, 95 %CI: -29.1 to -16.5, I2 = 97.5 %, p < 0.001), and a significant increase in both Tear Break-up Time (MD: 2.2 s, 95 %CI: 0.9 s to 3.4 s, I2 = 98.6 %, p < 0.001) and Schirmer test (MD: 1.5 mm, 95 %CI: 0.6 mm to 2.5 mm, I2 = 0.0 %, p = 0.001) at ≤ 3 months post treatment. These improvements were sustained in a sensitivity analysis at endpoints ≥ 6 months post treatment. While the percentage of loss of meibomian gland area (n = 4, MD: -3.8 %, 95 %CI: -7.2 % to -0.4 %, I2 = 40.0 %, p = 0.031) was reported to be significantly reduced, this was not found to be sustained at endpoints ≥ 6 months post treatment (n = 2, MD: 5.9 %, 95 %CI: 1.8 % to 10.0 %, I2 = 0.0 %, p = 0.005) in two studies.

CONCLUSIONS

This meta-analysis provides quantitative evidence supporting the clinical efficacy of LLLT + IPL therapy in MGD. Future research should evaluate its long-term safety and efficacy and compare it with alternative treatments.

Advances in clinical examination of lacrimal gland

In humans, the lacrimal gland is located in the socket of the frontal bone above the outer orbital area. As an essential part of the eye surface, the gland is fixed to the orbital periosteum by connective tissue. The lacrimal gland passes through the outer tendon membrane, which divides the gland into larger orbital and minor eyelid glands. The lacrimal glands are the main contributors to tear film. They secrete electrolytes, proteins, and water to help nourish and protect the eye's surface. Furthermore, clinically, lacrimal glands are associated with a variety of inflammatory reactions and immune factors and are also vulnerable sites for tumors. Changes in tear gland morphology or secretory function affect tear film stability and tear secretion quality. Various technological devices have been developed and applied to lacrimal glands. This article systematically reviewed the clinical examination of the lacrimal gland to help inform personalized strategies for the diagnosis of lacrimal gland-related diseases.

Tear Biomarkers and Alzheimer's Disease

Alzheimer's disease (AD) is an age-related progressive neurodegenerative brain disorder that represents the most common type of dementia. It poses a significant diagnostic challenge that requires timely recognition and treatment. Currently, there is no effective therapy for AD; however, certain medications may slow down its progression. The discovery of AD biomarkers, namely, magnetic resonance imaging, positron emission tomography and cerebrospinal fluid molecules (amyloid-β and tau) has advanced our understanding of this disease and has been crucial for identifying early neuropathologic changes prior to clinical changes and cognitive decline. The close interrelationship between the eye and the brain suggests that tears could be an interesting source of biomarkers for AD; however, studies in this area are limited. The identification of biomarkers in tears will enable the development of cost-effective, non-invasive methods of screening, diagnosis and disease monitoring. In order to use tears as a standard method for early and non-invasive diagnosis of AD, future studies need to be conducted on a larger scale.

Recharacterization of superior limbic keratoconjunctivitis via a subdividing grading method in 236 Chinese patients

PURPOSE

Superior limbic keratoconjunctivitis (SLK) is an uncommon and often overlooked chronic ocular surface disease. This retrospective consecutive case series study on Chinese patients aimed to characterize the features of this disease, including those undescribed in previous literature.

METHODS

Two hundred thirty-six patients diagnosed with SLK were enrolled into this consecutive case study from 2016 to 2019. The demographics, symptoms, Ocular Surface Disease Index, and ocular signs were collected and analyzed. A scoring system (SLK scale index, SSI) that integrated five major sign scores was applied to evaluate SLK severity.

RESULTS

Of the 236 SLK patients, dryness was the most common complaint (59.3%). Of 459 SLK eyes, superior limbus/conjunctival staining (SCS) was present in 98% eyes, followed by the superior tarsal conjunctival alterations (85.2%) and superior bulbar conjunctiva hyperemia (80.8%). Approximately 63% of eyes were accompanied by corneal staining. Superior bulbar conjunctivochalasis was a relatively rare sign (41.6%). Among the five major signs, only the prevalence of SCS gradually increased with its severity. In addition, fluorescein staining at the inferior limbus and adjacent conjunctiva (ICS) was found positive in 163 eyes of 84 patients (36%) who had significantly higher SSI than those without ICS (p = 0.013).

CONCLUSIONS

We found that SCS is the most common out of the 5 typical signs of SLK. ICS, a new sign, occurred in one-third of patients. SCS, a simple marker of SLK, as well as SSI, an integrated evaluation system, had the advantage of evaluating the severity and objectively characterizing SLK in clinical practice.