Meibomian gland dysfunction (MGD) is currently considered a crucial factor in dry eye disease. The treatment of MGD underwent a revolution in the past years: in addition to classical self-administered options such as warm compresses, lid massage and several types of ocular lubricants, new in-office targeted therapies are now available. Intense pulsed light (IPL) is broad spectrum high-power light pulsed that, in controlled trials, has been shown to improve tear film quality and symptoms. It may be more effective than eyelid hygiene in improving meibomian gland structure and reducing inflammation.9The proposed mechanisms for its effectiveness are ablation of superficial blood vessels in the eyelids, leading to a reduced supply of inflammatory agents; reduction of bacterial and parasitic growth; meibum liquefaction, and collagen remodeling.
Low-level light therapy (LLLT) is a different type of photomodulation, where low-power monochromatic red light is applied for a longer period, promoting tissue repair, antioxidation and reducing inflammation. Marques et al evaluated the safety and effectiveness of LLLT when associated with IPL for the treatment of MGD in an observational study. Two groups of patients that were treated with IPL were considered: group 1 (31 subjects, 62 eyes), intense pulsed light followed by low-level light therapy and group 2 (31 subjects, 62 eyes) intense pulsed light alone. In both groups, treatments were performed in 3 sessions and subjects were evaluated at baseline and 3 weeks after the last treatment session. Values are shown as mean difference ± standard deviation.
Authors observed a significant improvement in OSDI-12 score and lipid layer thickness, in both groups (−22.7±17.5, p<0.001 in group 1 and −23.6±23.8, p><0.001 in group 2 for OSDI and +18.6 ± 37.0, p><0.001 in group 1 and +19.9 ± 26.4, p><0.001 in group 2 for lipid layer thickness). Despite no differences between groups at baseline (p=0.469), only group 1 had a significant improvement in Schirmer test (+1.6±4.8, p=0.009 in group 1 and +1.7±6.9, p=0.057 in group 2). No significant side effects were noted. No patient in any group felt subjectively "worse" after the treatment.>< 0.001 in group 1 and −23.6±23.8, p< 0.001 in group 2 for OSDI and +18.6 ± 37.0, p<0.001 in group 1 and +19.9 ± 26.4, p><0.001 in group 2 for lipid layer thickness). Despite no differences between groups at baseline (p=0.469), only group 1 had a significant improvement in Schirmer test (+1.6±4.8, p=0.009 in group 1 and +1.7±6.9, p=0.057 in group 2). No significant side effects were noted. No patient in any group felt subjectively "worse" after the treatment>< 0.001 in group 1 and +19.9 ± 26.4, p< 0.001 in group 2 for lipid layer thickness). Despite no differences between groups at baseline (p=0.469), only group 1 had a significant improvement in Schirmer test (+1.6±4.8, p=0.009 in group 1 and +1.7±6.9, p=0.057 in group 2). No significant side effects were noted. No patient in any group felt subjectively "worse" after the treatment.
The reduction in OSDI may be accompanied by a placebo effect from inclusion in the study but may also be associated with less eyelid inflammation and better tear film quality after treatment. The anti-inflammatory properties of IPL are thought to be one of its main benefits in tear film homeostasis. Authors postulated that the increase in LLT is a consequence of the improved outflow of meibum from the glands and their enhanced function and morphology, as it has been already described.
In both groups, LLT increased equally and on average 39% from baseline to the post-treatment visit and 30% of cases reached normal values. Still, the other 70% of cases did not reach the normal value of LLT at 1 month, a result that should be interpreted carefully. An improvement in patients with MGD may be clinically significant even if normal values (calculated for a healthy population) are not met. Moreover, it has been showed that LLT may further improve up to 6 months after the treatment.
"In summary, our results suggest that IPL is effective and safe in the short term for the treatment of MGD. Combining LLLT to IPL may additionally improve lacrimal gland function and tear production, but further studies must confirm this finding."
Source: Marques et al; Clinical Ophthalmology 2022:16
https://doi.org/10.2147/OPTH.S384360