Photoblepharokeratoconjunctivitis caused by invisible infrared radiation emitted from a green laser pointer

Abstract

There are a wide variety of laser pointers sold to the general public. Among those are the high-powered diode-pumped solid-state lasers (>5 mW), which do not follow the laser safety regulations for packing, and are sold as regular lasers without the infrared (IR) filters. In this case report, we encountered a patient with photoblepharokeratoconjunctivitis caused by the invisible IR radiations emitted from a green laser pointer. Owing to the thermal effect of the invisible IR rays led to the disease.

Background

Commercial laser pointers are intended to have less than 5 mW total power. At such low power levels, an infrared (IR) filter for a diode-pumped solid-state (DPSS) laser is usually not required. However, high-powered DPSS laser pointers (>5 mW) are now available to the general public, usually through suppliers who do not follow the laser safety regulations for laser packing. These high-powered lasers are frequently packed in the same pointer style housing as regular laser pointers but without installing the IR filters found in professional high-powered DPSS lasers because of its high costs.¹

In this case report, we present the effect of a DPSS laser pointer without the IR filter on the eyelids, cornea and conjunctiva.

Case presentation

A female patient in her fourth decade presented to the ophthalmology outpatient clinic in July 2013, reporting that she had hazy, painful eyes with difficulty in opening them for the past 2 days.

On examination, the patient had ecchymosis of upper and lower eyelids resembling a first-degree skin burn, associated with blepharospasm. After applying local anaesthetic eye drops, her visual acuity was hand movement, in both eyes. The conjunctiva was severely congested, bulbar more than palpebral, with bilateral diffuse corneal opacification. Slit-lamp biomicroscopy, after fluorescein staining, revealed severe superficial punctate keratitis covering the entire surface of the cornea, associated with extensive corneal oedema and circumferential epithelial desquamation excluding the superior part of the cornea. This in turn prevented any descent view of the anterior chamber. The patient denied being exposed to any direct ultraviolet rays, IR rays or chemicals.

At the end of the examination, the patient mentioned that her 13-year-old son played with her by pointing his new green laser pointer (which she bought for him) at her eyes. On further enquiry, it became apparent that she was subjected to the laser pointer for 15–30 min at a distance of 1–2 m, on two consecutive days before her visit to the clinic, where the patient started to report her symptoms on the second day (less than 24 h after exposure).

She was requested to bring the laser pointer and it was found that it had an on/off button not a pressure knob, which would produce a continuous radiation.

The following specifications were copied of a label on the laser pointer (as claimed by the manufacturer):

• Max output power <200 mW

• Wave length 532 nm±10

• Class III laser product

• This product complies with 21 Code of Federal Regulations (CFR)

The patient was diagnosed as a case of IR-induced photoblepharokeratoconjunctivitis and was given cyclopentolate eyes drops and topical antibiotic ointment.

After 2 days, epitheliopathy started to settle down and visual acuity went up to 0.2 in the right eye and 0.3 in the left eye and local corticosteroids were added to the treatment.

There was a continuous improvement of her symptoms, where after another 2 days her visual acuity was 0.5 in the right eye and 0.6 in the left eye, funduscopy showed no signs of retinal affection and the lid ecchymosis improved leaving bilateral lower lid haematoma.

Outcome and follow-up

Follow-up after 10 days showed that her condition was completely resolved. However, it is too early to comment on the involvement of the lens after this intense exposure to IR rays.

Discussion

Can IR radiations emitted from a laser pointer cause harmful effects to the eye and its surrounding structure? After a literature search on this topic, it was found that the answer to that question is a definite yes. A study from the national institute of standards and technology (US Department of commerce) has measured the output power of lasers in this category and found that it emits 10 times more the invisible IR light than the visible green light.¹ Nevertheless, the extent of damage depends on the power of the laser pointer, the duration of exposure to the beam, the angle at which the beam comes in contact with the eye and the distance between the laser pointer and the eye.² A similar case report by Kandari et al was published in 2010, mentioning two patients, the first of whom was exposed to a laser used in military warfare and the other was exposed to a laser pointer. Both of them suffered from reduced visual acuity. On follow-up after 7 months, the patient who was exposed to the laser pointer had improved visual acuity up to 20/25 with no retinal damage.³ Another study by Robertson et al was conducted on three patients, all of whom suffered from uveal melanoma, and agreed to take part in an experiment by having their retina exposed to a laser beam from a class 3A laser pointer. None of them produced recognisable retinal damage after continuous durations of exposure up to 15 min.⁴ But that was conducted by a class 3A laser while the patient in our case was exposed to a class 3B as the laser pointer generated more than 5 mW and less than 200 mW.

Although retinal damage should be suspected in any patient with decreased visual acuity after obvious exposure to high-intensity laser beams, fortunately to the patient, this was not the case, as the IR radiations emitted from the laser pointer have caused ecchymotic skin changes in the eyelids resembling those of first-degree skin burns, as well as conjunctival congestion and severe superficial punctate keratitis but no laser-induced retinal damage. All these changes are due to the thermal effect of the invisible IR rays from the laser pointer due to the lack of IR filters.⁵ However, the case was not presented with retinal damage as the laser beam was pointed from the sides of the face and not directly into the eyes.

Learning points.

• Laser pointers are very dangerous instruments that should not be taken lightly nor should they be used or sold to people under 18 years, as they are hazardous to the eyes.

• An international law forbidding the sale of such cheap high-power laser pointers without the IR filters should be taken into consideration.

• Strict control of the manufacturers who produce such laser pointers will definitely reduce the risk of hazards to the eye.

• The media has to take the matter of laser pointers quite seriously through public health education and stressing on the hazards of using laser pointers.