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Light Therapy: A Promising Treatment Option For Infected Skin Ulcers

Light Therapy: A Promising Treatment Option For Infected Skin Ulcers


The meta-analysis aimed to assess and compare the efficacy of photodynamic light therapy (PDT) in treating infected skin wounds. Analyzing data from six studies conducted between 2013 and 2021, involving a total of 154 patients with infected skin wounds, the meta-analysis utilized random- or fixed-effect models to calculate odds ratios (OR) and mean differences (MD) with 95% confidence intervals (CIs).


The findings indicated that PDT resulted in significantly reduced wound ulcer size (MD, -4.42; 95% CI, -7.56 to -1.28; p = 0.006), improved tissue repair (MD, -8.62; 95% CI, -16.76 to -0.48; p = 0.04), and decreased microbial cell viability (OR, 0.13; 95% CI, 0.04–0.42; p < 0.001) compared to red light exposure in individuals with infected skin wounds.


Overall, PDT demonstrated superior outcomes in terms of wound healing and microbial reduction when compared to red light exposure in infected skin wounds. However, it is important to note that all included studies had small sample sizes, thus warranting cautious interpretation of their findings.



Ulcers, which disrupt the natural tissue structure and impair epithelial function, can vary from minor epithelial breaks to severe lesions affecting deeper tissues like muscles, arteries, nerves, and bones. Common causes include surgical procedures, burns, radiation, and pressure from underlying medical conditions like diabetes or vascular disease. Skin ulcers pose a significant public health concern due to their high incidence and prevalence rates, leading to increased patient mortality and early impairment.


Delayed healing exacerbates the condition, causing pain, emotional distress, social isolation, and functional limitations, hindering daily activities. Recurring infections are a primary obstacle to healing, and while prescription antibiotics are commonly used, their efficacy is diminishing due to overuse and the emergence of multidrug-resistant bacterial species. Consequently, alternative treatments such as hydrotherapy, hyperbaric oxygen, negative pressure therapy, and ultrasound have been explored but with declining effectiveness.


In this context, photodynamic light therapy (PDT) emerges as a promising option utilizing light therapy in the treatment of infected wounds. PDT, a form of light therapy, utilizes specific light sources and oxygen-related photosensitizing chemicals to induce minimally invasive cell death. When combined with other medications to enhance efficacy, PDT has demonstrated utility in treating antibiotic-resistant bacteria. Importantly, PDT has not been associated with microbial resistance, as its mechanism involves generating singlet oxygen to damage multiple target cell compartments, swiftly eliminating bacteria.


This study seeks to conduct a systematic review and meta-analysis on the effectiveness of PDT for treating chronically infected wounds based on randomized clinical trials. Given that chronic wounds affect millions worldwide and incur substantial annual healthcare costs, understanding the advancements in PDT for infection treatment is crucial for improving patient outcomes and healthcare management.



Inclusion Criteria

  1. Study Design: The investigation must be an observational, prospective, retrospective, or randomized clinical trial.
  2. Population: Patients with skin wounds are the subjects of the study.
  3. Intervention: The intervention being evaluated is photodynamic light therapy.
  4. Outcome: The research must assess the impact of photodynamic light therapy’s effectiveness in treating infected skin wounds.


Exclusion Criteria


  1. Studies with a non-comparative design are not included.
  2. The assessment excludes letters, books, reviews, or book chapters.


The search strategy followed the PICOS principle:

Population: Patients with skin wounds.

Intervention/Exposure: Photodynamic light therapy.

Comparison: Comparison between photodynamic light therapy and red light therapy exposure.

Outcome: Wound ulcer size, tissue repair, and microbial cell viability.

Study Design: No restrictions were placed on the study design.


Databases including OVID, PubMed, the Cochrane Library, Embase, and Google Scholar were systematically searched until December 2023. All publications in the reference management program were reviewed, including abstracts and titles. Additionally, relevant studies not linking the type of treatment to clinical outcomes were included. Two authors independently evaluated papers to identify pertinent studies.

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Screening of studies involved assessing examination and personal features presented in a standard format, including the first author’s last name, examination time and year, nation of conduct, population type, total number of individuals, qualitative and quantitative evaluation methods, demographic information, and clinical and treatment characteristics. Two anonymous reviewers evaluated the potential for bias in each study and the quality of methods used. Lastly, two reviewers objectively examined the techniques employed in each study.



In the current meta-analysis, both dichotomous and continuous random- or fixed-effect models were employed to determine the odds ratio (OR) and mean difference (MD), along with their respective 95% confidence intervals (CI). The degree of heterogeneity among the included studies was assessed using the I2 index, which ranges from 0 to 100. Higher I2 values indicate increased heterogeneity, whereas lower values suggest decreased heterogeneity. If the I2 value exceeded 50%, the random-effect model was applied; otherwise, the fixed-effect model was utilized. The initial investigation’s results were stratified into subcategories for further analysis. To evaluate publication bias, Begg’s and Egger’s tests were conducted, with bias deemed present if the p-value exceeded 0.05. Two-tailed analyses were employed to calculate p-values. Graphs and statistical analyses were generated using Jamovi.


After reviewing 675 pertinent papers, six studies published between 2013 and 2021 were deemed eligible for inclusion in the meta-analysis, meeting the predefined criteria. These studies collectively involved 154 patients with infected skin wounds, of which 79 received photodynamic light therapy and 75 were subjected to red light therapy. Photodynamic light therapy demonstrated a statistically significant reduction in wound ulcer size (MD, -4.42; 95% CI, -7.56 to -1.28; p = 0.006) with no observed heterogeneity, improved tissue repair (MD, -8.62; 95% CI, -16.76 to -0.48; p = 0.04) with high heterogeneity, and decreased microbial cell viability (OR, 0.13; 95% CI, 0.04–0.42; p < 0.001) without heterogeneity compared to red light exposure among individuals with infected skin wounds. Evaluation of publication bias using the quantitative Egger regression test and visual inspection of the effect’s forest plot did not reveal any evidence of bias in the studies. Notably, most of the relevant studies exhibited low methodological quality and were impartial in their selective reporting.



The meta-analysis scrutinized findings from six studies spanning from 2013 to 2021, collectively involving 154 individuals grappling with infected skin wounds. Among these, 79 subjects were subjected to photodynamic light therapy, while 75 underwent treatment with red light exposure. Impressively, photodynamic light therapy emerged as a standout contender, showcasing notable improvements across various parameters compared to its counterpart.


Specifically, the data unveiled a significant reduction in wound ulcer size among individuals treated with photodynamic light therapy, coupled with enhanced tissue repair dynamics and a notable decline in microbial cell viability. These outcomes underscored the therapeutic potential of photodynamic light therapy in managing infected skin wounds, offering a ray of hope in an otherwise challenging clinical landscape.


However, the validity of these findings hinges on a critical caveat: the relatively modest sample sizes characteristic of all the included studies, each comprising no more than 50 participants. Such limited sample sizes warrant cautious interpretation of the results, urging researchers and clinicians alike to exercise prudence when extrapolating these findings to broader clinical contexts.


Furthermore, the etiology of skin wounds extends beyond mere external factors like pressure or shear, often intertwining with underlying systemic conditions such as diabetes or vascular disease. This nuanced understanding underscores the multifactorial nature of wound pathophysiology, necessitating a comprehensive approach to treatment that addresses both the acute injury and any underlying medical comorbidities.


Chronic wounds, encompassing diverse presentations like pressure injuries, diabetic foot wounds, septic wounds, and varicose ulcers, exact a significant toll on both healthcare systems and individual patients worldwide. These wounds pose formidable challenges to clinicians, often resisting conventional therapeutic interventions and perpetuating cycles of morbidity and healthcare expenditure.


In light of these challenges, the emergence of novel therapeutic modalities like photodynamic light therapy represents a beacon of hope in the quest for more effective wound management strategies. By harnessing visible light to activate photosensitizers and oxygen, photodynamic light therapy induces a localized inflammatory response that fosters tissue repair and curtails microbial proliferation—a paradigm shift in wound care paradigms.


Key to the success of photodynamic light therapy is the judicious selection of photosensitizers, with compounds like 5-aminolevulinic acid and tetracationic Zn (II) phthalocyanine demonstrating remarkable efficacy in preclinical and clinical studies. These photosensitizers exhibit potent bactericidal and fungicidal properties, offering a tantalizing glimpse into the future of wound therapeutics.


Nevertheless, the journey towards widespread adoption of photodynamic light therapy in clinical practice is fraught with challenges. Despite promising initial findings, the efficacy of photodynamic light therapy warrants validation through rigorous randomized controlled trials, incorporating blinding techniques to mitigate bias and enhance the robustness of the evidence base.


Moreover, exploring innovative treatment paradigms like combined photodynamic light therapy with photobiomodulation holds immense promise in further optimizing therapeutic outcomes. By synergistically harnessing the therapeutic potential of light-based interventions, such approaches offer a tantalizing glimpse into the future of wound management.


Yet, amidst the optimism surrounding photodynamic light therapy, it’s imperative to acknowledge the inherent limitations of the current meta-analysis. Potential assortment bias and incomplete data represent notable caveats, underscoring the need for continued vigilance and methodological rigor in future research endeavors.


In essence, while photodynamic light therapy holds immense promise as a novel therapeutic modality for managing infected skin wounds, its widespread adoption hinges on the robustness of the evidence base and the meticulousness of future research efforts. As such, a concerted interdisciplinary approach, marrying insights from clinical research, translational science, and healthcare delivery, is imperative in realizing the full therapeutic potential of photodynamic light therapy in wound management.



Analysis of the data indicates a clear advantage of photodynamic light therapy over red light therapy in treating infected skin wounds. Photodynamic light therapy led to notable reductions in wound ulcer size, improved tissue repair, and decreased microbial cell viability. Despite these promising findings, it’s essential to consider the limitations posed by the relatively small sample sizes in all the studies included. Therefore, while the results are encouraging, caution should be exercised in interpreting them, and further research with larger sample sizes is warranted to validate these observations conclusively.

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