## 3 Current Applications  
### Ocular Surface System  
#### 3.1.1 Dry Eye Disease  
Treatment and Prophylaxis  
The understanding of dry eye disease (DED) as a multifactorial condition involving tear film dynamics, ocular surface inflammation, and neurosensory abnormalities has evolved in recent decades, as highlighted by TFOS DWES II definition. A crucial distinction is made between aqueous-deficient and evaporative types, with the latter, often associated with meibomian gland dysfunction (MGD), being more prevalent [14]. Meibomian glands, located in the eyelids, play a crucial role in tear film stability by secreting meibum. In cases of obstructive MGD, the glands undergo pathological changes leading to meibum stasis, duct obstruction, and ultimately acinar atrophy. This process contributes to tear film instability, increased evaporation, and the initiation of a detrimental cycle marked by inflammation and elevated tear osmolarity [15; 16; 17; 18]. Photoibomodulation therapy has emerged as a potential treatment for MGD. The hypothesis suggests that PBM stimulates ATP production in the meibomian glands, inducing \begin{table}
\begin{tabular}{c c} \hline \hline
**Treatment** & **Disease** \\ \hline \multirow{4}{*}{\"Photobiomodulation\" OR \"Low-level light therapy\"} & \"Dry eye disease\" OR \"Chatazion\" OR \"Cataract\" OR \"Meibomian gland dysfunction\" OR \"Age related macular degeneration\" OR \"D Diabetic retinopathy\" OR \"Myopia\" OR \"Amblyopia\" \"Glucoma\" OR \"Retinopathy of prematurity\" OR “Ophthalmology\" OR “Eye” \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Search strategy and key words used during the literature review. endogenous heating and facilitating meibum flow. While there is a considerable body of research on the combined use of LLLT and intense pulsed light (IPL) technologies, the effectiveness of LLLT as the only therapy in DED associated with MGD is an area with limited exploration. Three articles addressing the efficacy of LLLT alone have been identified. [PERSON] and collaborators conducted a randomized, double-blind clinical trial involving 40 DED patients, showing positive effects of LED-LLLT. Light irradiation was performed with a LED-based array matrix module with 5 planar panels. For the first 1 min of irradiation, a wavelength of 590 nm in continuous wave and an irradiance of \(\approx\)50 uW/cm\({}^{2}\) were scanned panel by panel for 1 s per panel, giving a fluence of \(\approx\)50 uJ/cm\({}^{2}\). At the end of that minute, 830 nm was delivered from all 5 panels at an irradiance of 100 mW/cm\({}^{2}\) for 10 min in continuous wave mode. The system is LED-based, and the irradiance was below the ANSI values for maximum permissible exposure (MPE). The energy density over the entire near field area (encompassing the entire face and orbital area) was therefore \(\approx\)60 J/cm\({}^{2}\) per session (HEALITE II, Lutronic, Goyang, Republic of Korea), with a distance between the treatment head and target tissue of approximately 17 cm [19]. [PERSON] and co-authors compared LLLT and IPL both performed using the Eye Light device (Espansione Group, Bologna, Italy), reporting significantly higher improvements in symptoms and tear film volume after LLLT compared to IPL [20]. Additionally, an at-home LLLT miniaturized device called my-mask (Espansione Group, Bologna, Italy) has been introduced in the market, showing positive results without adverse events during a study conducted by the same group of authors. Light irradiation was performed with 15 min of irradiation at 625 nm \(\pm\) 40 nm wavelength in continuous wave, an irradiance of \(\approx\)35 mW/cm\({}^{2}\) and the standard dose transferred to the patient of 32 J/cm\({}^{2}\)[21]. Among the various types of DED, TFOS DEWS II identified the atrogenic cause owing to different ocular surgeries and, in particular, senile cataract surgery. In fact, patients undergoing this surgery may have pre-existing ocular surface alterations that could either be revealed or exacerbate postoperatively.