Laser-induced CNV following hair removal procedure

Objective: To describe the chronological features of choroidal neovascular membrane (CNV) development subsequent to accidental firing of diode laser into the eye of a young female during hair epilation. Methods: Descriptive case report. Results: The patient presented one week after the laser injury to a local ophthalmologist complaining of RE (right eye) blurred central vision. Snellen’s visual acuity (VA) was 6/ 7.5. Optical coherence tomography (OCT) showed focal disruption of the ellipsoid and the interdigitation zones. Four weeks later, she presented with worsening symptoms and RE VA 6/ 15. Funduscopy revealed a perifoveal grayish lesion with adjacent retinal hemorrhage, which, on fluorescein angiography, was leaking, compatible with CNV. OCT showed a dome-shaped sub-retinal pigment epithelium lesion with extension into the subretinal space and little subretinal fluid. The patient was treated with one intravitreal bevacizumab injection. There was rapid regression of the CNV and improvement of VA to 6/ 7.5 at one-month visit and to 6/ 6 at 6-month visit. Conclusion: All the laser procedures should be conducted with intensive care for both the patient and the laser surgeon since inadvertent effects are constantly being reported due to lack of adherence to safety measures.


Introduction
Laser or light-based hair removal is one of the most commonly used medical procedures nowadays, with increasing addressability to our society. Although the information about the lasers' ability to nonspecifically damage hair follicles dates to over 50 years ago, the first successful laser for long-term hair removal was proposed in the late '90s, after confirming the selective photothermolysis theory [1].
Melanin functions as a target chromophore for wavelengths in the red and near infrared portion of the electromagnetic spectrum, but in order to achieve permanent hair depletion, heat needs to diffuse from the "light" target towards the "biological" target, namely the follicular stem cells [2]. Depending on the photons' wavelength, hair removal is most commonly achieved by red spectrum ruby (694 nm), alexandrite laser (755 nm), diode laser (700-1000 nm), neodymiumdoped yttrium aluminum garnet laser (Nd:YAG laser, 1064 nm), as well as by intense pulsed light devices (IPL, 590-1200 nm) [3]. Beside wavelength, other factors important both for therapeutic and safety purposes include fluence (J/ cm 2 ), pulse duration (ms), spot size (mm), adjuvant skin cooling systems and the Fitzpatrick skin phototypes. photochemical mechanisms [4]. Although more than one effect might induce a particular injury, short wavelength lasers produce photocoagulation (the increase of the retinal temperatures to approximately 60˚C generates protein denaturation), while long wavelengths might affect the ocular tissue through either photothermal and/ or photomechanical damage (the explosive acoustic shock shears, fragments and perforates the tissue) [4].
Diode lasers for epilation may generate all the relevant wavelengths for hair removal (694 nm, 755 nm, 800/ 810 nm, 980 nm, 1064 nm) and next-generation lasers will be able to simultaneously apply multiple wavelengths [5]. The most common ocular adverse effects induced by diode lasers involve the iris, encompassing anterior uveitis and iris damage followed by iris atrophy and/ or pupillary distortion [6]. Lens involvement includes anterior subcapsular and nuclear cataract. The retina, which is responsible for converting electromagnetic radiation into an electric signal, is particularly vulnerable to wavelengths in the visible to near-infrared spectrum (400nm-1400nm), known as the retinal hazard region [6]. Vitreous hemorrhage, retinal burns with edema, chorioretinal scarring, foveal granularity, pigment clumping, subretinal hemorrhage with consecutive photoreceptors' damage and macular holes have all been described, either secondary to facial laser procedures (hair removal or skin treatments) or to accidental exposure to industrial and military lasers [6,7]. Although the development of an experimental animal model of laser-induced subretinal neovascularization for macular degeneration dates back to the late '70s, this is, to our knowledge, the first paper describing CNV formation secondary to diode laser injury in humans. There are very few other case reports of other types of laser-induced CNV formation following hair removal procedures, most of them showing complete and constant fluid resolution at one-month follow-up after one single intravitreal bevacizumab injection [8,9]. It seems that lesions with Bruch's membrane damage potentially lead to CNV and the endpoint bestcorrected VA depends on the magnitude of the scar formation in the fovea.
OCTA has recently emerged as a noninvasive imaging modality, depicting a real potential of replacing FA/ ICG to assess CNV in OCT imaging. Being a noninvasive substitute for FA/ ICG, but providing comparable functional information to the one obtained from dye-based angiography [10], it can clearly depict features of CNV activity versus regression.
This report outlines a new case of laserinduced CNV caused by diode laser that was used in hair epilation, in the absence of any type of ocular protection. Misdirection of the laser beam towards the eye has visual-threatening consequences. Proper eye protection is critical for both the patient and the laser surgeon. Manufacturers recommend the use of specific goggles (depending on the device's wavelengths), gauze sponges under opaque goggles to ensure eye closure or even corneal shields for interventions in the periocular area.