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Retinopathy from a Green Laser Pointer a Clinicopathologic Study

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Retinopathy from a Green Laser Pointer a Clinicopathologic Study CLINICAL SCIENCES Retinopathy From a Green Laser Pointer A Clinicopathologic Study Dennis M. Robertson, MD; Jay W. McLaren, PhD; Diva R. Salomao, MD; Thomas P. Link, CRA Objective: To report retinopathy following exposure to 5 mW. Retinopathy was observed 24 hours after laser ex- light from a commercially available class 3A green laser posure. This was characterized by a yellowish discolora- pointer. tion at the level of the retinal pigment epithelium (RPE) in the subfoveal region and at the site superior to the Methods: A 55-year-old woman with a ring melanoma macula where the retina received 15 minutes of laser ex- was scheduled for enucleation. The eye (visual acuity 20/ posure. Each site developed granular changes at the level 20) had a healthy-appearing macular retina. The retina of the RPE within 5 days of exposure. Histologic study was exposed to light from a commercially available class showed RPE damage in the exposed subfoveal and para- 3A green laser: 60 seconds to the fovea, 5 minutes to a foveal regions. site 5° below the fovea, and 15 minutes to a site 5° su- perior to the fovea. Color photographs were obtained be- Conclusion: A class 3A green laser pointer caused vis- fore and after exposure. The eye was enucleated 20 days ible retinopathy in the human eye with exposures as short after exposure. as 60 seconds. Results: Laser power measurements averaged less than Arch Ophthalmol. 2005;123:629-633 E REPORT THE DE- patient was unable to discern any visual velopment of clini- abnormality and could not discern a sco- cally recognizable toma on tangent screen or Amsler grid test- retinopathy follow- ing 6 and 20 days after exposure. Twenty- ing exposure of the four hours after exposure, fundus Whuman eye to light from a commercially examination revealed a distinct yellow- available class 3A green laser pointer. A ish discoloration in the subfoveal region 55-year-old woman with a ring mela- at the level of the retinal pigment epithe- noma that involved the ciliary body was lium (RPE). An area of yellowish discol- scheduled for enucleation. The eye had a oration was also recognized at the retinal healthy-appearing macular retina and good site exposed to the laser for 15 minutes. visual function (visual acuity 20/20). The A delicate granular irregularity devel- patient agreed to have her retina exposed oped in each site at the level of the pig- to laser light from the green laser pointer ment epithelium and was recognizable at before enucleation. Continuous expo- the 6- and 20-day follow-ups. Histologic sure was directed to the fovea for 1 minute, study of the enucleated eye showed a cho- to the retina 5° below fixation for 5 min- roidal melanoma in the ciliary body, and utes, and to the retina 5° above fixation for thick sections revealed apical displace- 15 minutes. The retina was evaluated oph- ment of the nuclei of some RPE cells in thalmoscopically and the fundus was docu- the subfoveal region. The pigment gran- mented by color photography before, 24 ules were also displaced into the outer re- hours after, and 6 and 20 days after laser ceptor layer, and many intracytoplasmic exposure. Transient pink afterimages were granules displayed irregular shapes and Author Affiliations: observed by the patient for approxi- density characteristics of melanofuscin. Department of Ophthalmology, Mayo Clinic, Mayo Foundation, mately 4 minutes after the laser expo- Displacement of some of the pigment and Mayo Medical School, sure. The patient’s visual acuity was re- epithelial cells into the subretinal space Rochester, Minn. corded as 20/20 the day after exposure and was also observed at the exposed site. Financial Disclosure: None. 20/20 at 6 and 20 days after exposure. The Although in this experiment a class 3A (REPRINTED) ARCH OPHTHALMOL / VOL 123, MAY 2005 WWW.ARCHOPHTHALMOL.COM 629 ©2005 American Medical Association. All rights reserved. green laser pointer caused retinopathy with exposures low the center of the Amsler grid. The pupil of the eye that con- as short as 60 seconds, the recognized ophthalmoscopic tained the tumor was dilated to 8 mm with 2% cyclopentolate and histologic abnormalities were unaccompanied by hydrochloride and 10% phenylephrine hydrochloride. The other visually perceptible abnormalities. eye was doubly patched. The eye that contained the mela- In a previous study,1 we reported the absence of reti- noma was subjected to 3 durations of exposure from the laser pointer. nal injury following retinal exposures of laser light from The retina was exposed to light from a handheld green la- commercially available class 3A red laser pointers with ser marketed as a laser pointer (LightVision Technologies Corp, powers of 1, 2, and 5 mW. Three human eyes were ex- Kaoyuan, Taiwan). Light output was continuous (not pulsed) posed to light from these laser pointers for 1, 5, and 15 and specified by the manufacturer as less than 5 mW at 532 minutes. We documented no functional, ophthalmo- nm. The beam power was measured with a radiometer (IL 700, scopic, histologic, or ultrastructural abnormalities that SEE-100 probe; International Light Inc, Newburyport, Mass). could be attributed to the laser exposures. We con- From information relating to the retinal hazards of intrabeam cluded that the risk to the adult human eye from tran- viewing of lasers specified by the American National Standard 4 sient exposure to light from these red laser sources was for the Safe Use of Lasers, we calculated maximum permis- negligible, although 2 credible reports2,3 have been pub- sible exposure at various exposure times. Exposures were administered as follows. The patient fix- lished of visible retinal abnormalities after exposure to ated her gaze for 60 seconds directly at the laser beam as it passed red laser pointers in 2 young patients, one 11 years old through the center of the aperture in the Amsler grid. Then the and the other 19 years old. Green laser pointers have been patient fixated her gaze for 5 minutes on the fixation target 2½ used interchangeably with red laser pointers by some lec- squares below the aperture and the laser beam. The last expo- turers, and green laser pointers are increasingly being used sure was a 15-minute fixated gaze on the fixation target 2½ by amateur astronomers as pointers to deep sky objects. squares above the aperture and the laser beam. Normal blink- Unlike the beam of the red laser, which cannot be seen ing was allowed during the exposures. During each exposure, well in ordinary night atmosphere, the beam from the the patient’s fixation was confirmed by one of us (D.M.R.), and green laser can be easily seen in the deep night sky, where the laser beam was maintained in the central 2 mm of the pa- it can point to a single star. Additionally, since the green tient’s widely dilated pupil. After each exposure the patient was asked to report any recognized afterimages or photopsias. Im- laser is visible in the daytime, when directed to outdoor mediately after responding to this request, the patient was in- objects of interest, the green laser pointer has proved use- structed to gaze at the center of a standard Amsler grid and re- ful to some instructors of outdoor painting, landscape port any defects in the grid. The patient wore corrective eyewear design, architecture, and construction. Since the retina for this last assessment. is increasingly more sensitive to shorter wavelengths, we The patient returned the following day, 6 days after expo- were interested in learning if the green laser pointer could sure, and again 20 days after exposure for measurement of the cause retinopathy in the human eye. Snellen visual acuity, ophthalmoscopic examination with slit- lamp biomicroscopy aided by a Hruby lens and the 90-diopter (D) and 60-D fundus viewing lenses, and color photographic REPORT OF A CASE documentation of the fundus. The retina was examined by ocu- lar coherence tomography (OCT) 24 hours after laser expo- A 55-year-old woman with a ring melanoma of the cili- sure. The central visual field was studied 24 hours and 20 days ary body was scheduled for enucleation. The eye was nor- after laser exposure with the Amsler grid and tangent screen motensive and had an uncorrected visual acuity of 20/ evaluations with a 1-mm white target. Sites in the fundus that were exposed to the laser light were carefully inspected for ab- 20. The patient consented to participate in an experiment normalities. These sites included the fovea and the RPE com- during which a green laser pointer would expose her retina plex 5° superior and 5° inferior to the fovea. to light for intervals of up to 15 minutes. The study was approved by our institutional review board before the ex- periment, and our patient was fully informed of the na- RESULTS ture of the experiment and gave verbal and written in- formed consent to participate. The beam power of our green laser was variable and be- tween 3 and 7 mW, although the manufacturer stated that METHODS the light output was less than 5 mW. The maximum per- missible exposure is 0.39 mW for exposures between 1 An apparatus was designed to direct the laser beam from a class and 15 minutes, assuming a 7-mm limiting aperture (pu- 3A green laser pointer through a hole (5 mm in diameter cre- pil diameter).4 Retinal exposure from our laser ex- ated with a simple paper punch) in the center of a black Ams- ceeded this limit by 8 to 18 times. ler grid and then into the patient’s pupil to target the retina.
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