**4. Enhanced management and treatment for dry eye (DE)**

The 2017 TFOS DEWS II provides guidelines for a stepped treatment protocol for DE, which targets each abnormality in the Tear Film-Oriented Diagnosis (TFOD) approach (**Figure 2**) [17–19].

#### **4.1 Drug therapy**

The inflammation, along with dry eye usually treats with topical corticosteroids. In cases with little satisfaction, a second-line drug is Topical cyclosporine A [20].

Lifitegrast 5% is a second topical anti-inflammatory ocular drop that got FDA approved In July 2016 for DED.

Other drugs include lipid-containing eye drop, artificial tear formulations with nanostructured lipid carriers as a synthetic TF in vivo, and castor oil emulsions are promising as Preservative-free drops, omega-3 fatty acid, supplementation, serum tears, topical azithromycin, oral and topical HA oral doxycycline, topical 3% Diquafosol and cholinergic.

#### **4.2 Procedures**

Intense pulse light, lacrimal plug, lid massage and probing and expression of MG, warm compresses or vectored thermal pulsation, and amniotic membrane biologic corneal bandage lens have evolved to improve the signs and symptoms of DE.

## **5. Definition of IPL**

An intense pulsed light (IPL) system is a non-laser large source of light that produces a non-coherent light output of broad wavelength, usually in the range of 500 to 1200 nm, using a high-performance flashbulb. Many modern tools create light pulses by transmitting bursts of electricity running through a xenon gas-filled chamber [21–23].

The usage of IPL in medicine is based on the fact that unique load transfer targets (chromophores) can absorb photons from a wide range of light wavelengths (absorptive band) without being specifically targeted by their highest absorption.

*Intense Pulse Laser Therapy and Dry Eye Disease DOI: http://dx.doi.org/10.5772/intechopen.99165*

The IPL uses targeted photo thermolysis, in which thermally induced radiation harm is restricted to the selected epidermis and dermis textured targets at the cellular or tissue structural difference [24]. Toyos et al. reported improvements in MGD associated Dry Eye Disease (DED) cases in 2002 and was the first published report on using an IPL system in ophthalmology [25, 26]. IPL dilates the capillaries and causes them to involute using electromagnetic waves of specific wavelengths [27]. This causes the leaked inflammatory responses to be suppressed, interrupting the vicious cycle of inflammation and enhancing dry eye signs. In most cases, it also functions with the aid of thermal pulsation [28]. When chronic inflammation occurs, the structure of the meibum improves to contain many monounsaturated fats. Those fats have a melting point of close to 45°C, which is greater than body temp [29]. This meibum does not melt through the lipid coating of the tear film as it should, clogging the glands. Thermal pulsation treatment liquefies the meibum and clears the glands by combining continuous pressure and heat. Traditional manual expressing glands is ineffective, inconvenient for patients, and could result in scarring [29]. Thermal pulsation is an effective and safe treatment option. With these processes in mind, we have deduced that IPL will help alleviate the symptoms of DE [21, 30].

## **6. Causes of dry eye and applications of IPL**

The surface epithelial and glandular tissues (cornea, bulbar and palpebral conjunctiva, lacrimal and accessory eyelid), the glycocalyx, and the tear film consist of the microenvironment of the ocular surface [31].

Systemic disorders such as rheumatoid arthritis, Sjogren's syndrome, thyroid eye disease, sleep apnea [32], cicatrizing disease of the conjunctiva, contact lens wear, and refractive laser surgery are the most underlying associated conditions with Refractory DE. DE signs after Laser-Assisted in Situ Keratomileuses (LASIK) are not standardized. There is a continuum of disorders such as neurotrophic disease, tear film dysfunction, aqueous tear deficiency, and neuropathic pain conditions. Cutting the corneal nerves during Laser ablation and creating the flap are probable reasons for post-refractive DE. Meibomian glands are adjusted sebaceous glands located inside the lower and upper eyelids, with ducts terminating along the eyelid borders and secreting meibum, contributing directly to the lipid portion [31, 33].

The Tear Film Lipid Layer (TFLL) leads to the tear film's consistency and stabilization. The presence of TFLL on the tear film's exterior layer decreases the tear film's evaporation.

Negative TFLL changes may trigger evaporative DE, as well as symptomatic and clinical ocular surface manifestations [34]. Inflammation and illness TFLL were shown to be slightly lower in post-LASIK eyes, along with worsening DE symptoms and reduced corneal sensitivity [35].

A previous study reported the improvement of refractory DE with polar and nonpolar lipid base, ofloxacin eye ointment [36]. Another study reported the correlation between the severity of DE with lipid layer thickness secondary to increased evaporation as the most common etiologies for increased osmolarity of the tear film [37].

Scanning electron microscopy showed that lipids expressed by the meibomian gland caused extensive damage to gram-positive and gram-negative bacteria and hence acts as a protective barrier against pathogens [38]. Thus, improvement of the TFLL maintains the homeostatic balance by protecting the ocular surface environment. Therefore, the progress of symptoms and reduction of artificial tears after refractive surgery is another positive report about IPL treatment. However, future study elucidates the duration and the optimal dose [39, 40].
