We examined 2 new cases of postburn optic neuropathy, and 10 additional cases were identified in the medical literature. The onset was either immediate or delayed for weeks. Patients did not necessarily manifest symptoms of an encephalopathy before the onset of visual loss. Loss of vision was severe and bilateral in all cases, with disc edema present in most. Retinal hemorrhages and edema were observed in some cases. There was a capacity for spontaneous recovery.
We conclude that patients with cutaneous scalds or thermal burns may develop bilateral optic neuropathy, the pathogenesis of which has yet to be established. Visual loss following burns usually results from direct injury to the ocular surface. However, in some instances the visual loss is neurogenic. Our goal in presenting the following cases is to document the rarely reported occurrence of optic neuropathy following cutaneous thermal burns.
A 25-year-old man was burned on May 11, 1994, when the furnace that he was cleaning exploded, pinning him in a pit of smoldering ash. He did not lose consciousness and was alert but incoherent on admission to a local hospital, with partial- and full-thickness burns covering 90% of his body. His entire face was burned, and his eyelids were absent. Morphine and 10 L of intravenous fluid were administered. The patient was intubated, given a central line, paralyzed with drugs, and flown to a burn unit at another hospital. At the time of transfer, the size and reactivity of his pupils were described as normal.
The patient was alert and responding to commands on his arrival at the burn unit. His blood pressure was 170/110 mm Hg, and his pulse varied from 120 to 140 beats per minute. Arterial blood gas analysis showed a PO2 of 66 mm Hg, oxygen saturation 88.7%, pH 7.24, and total carbon dioxide 22 mm/L.The hemoglobin level was 215 g/L, and the hematocrit was 65%. During escharotomies, a fall in his oxygen saturation necessitated a cricothyroidotomy. He remained in the burn unit for 7 months, the first 4 of which he was maintained in a drug coma. His course was complicated by transfusions required for anemia, as well as transient renal failure, pneumonia, sepsis, and urinary tract and skin infections for which he received a variety of antibiotics. While in coma, he was examined several times by an ophthalmologist, who reconstructed his eyelids and treated him for bilateral exposure keratopathy complicated by an infection of the right cornea. There was no report of his pupillary reactions or of the fundus appearance.
When he was extubated 6 months after the accident, the patient reported poor vision in both eyes. This was initially ascribed to his corneal lesions. One month later, the patient complained specifically of a blind spot in the center of the visual field of both eyes. An ophthalmologist performed perimetry and concluded that he had bilateral optic neuropathy. Twenty-one months after sustaining his burns, the patient's vision was unchanged, and he was referred for neuro-ophthalmic evaluation.
His best-corrected visual acuities were 20/70 OD and 20/200 OS. Color vision (Ishihara) was normal in both eyes. There were bilateral central scotomas on testing with the Goldmann perimeter. Both corneas were scarred below the visual axis, but the anterior segments were otherwise normal. His pupillary reactions and eye movements were unremarkable. Applanation intraocular pressures were 15 mm Hg OD and 14 mm Hg OS. Both optic discs were atrophic with sharp margins and 0.6 cup-disc ratios. The fundi were otherwise normal. No abnormalities were found on the general neurological examination or on magnetic resonance images of the orbits. The patient was unchanged when reexamined 1 and 2 years later.
A 13-year-old girl suffered a flame burn in a house fire, which covered 85% of her body, including her face. Although further details are not available, it is known that the patient lost consciousness and then complained of poor vision when she first became sentient several days later. There had been no previous eye problems.
The patient was referred 3 months later because of impaired vision. At that time, she was alert and cooperative. Vision in her right eye was limited to counting fingers at 1 ft, and she could not see light with her left. Her color vision was nonexistent, and she could not cooperate for perimetry. Both pupils were dilated. The right had a faint response to light stimulation, whereas the left had none. Her ocular motility was unimpaired. The skin of all 4 eyelids was scarred. There was a slight central stromal haze of both corneas, but the conjunctivae, anterior chambers, irides, and lenses appeared normal. Her intraocular pressure seemed normal by palpation. The optic nerves were extremely pale with sharp margins. Both fundi were otherwise unremarkable. We were informed of subsequent improvement in vision.
Some patients with thermal burns suffer severe loss of vision even without direct injury to the eyelids or globes. Visual impairment in such cases is caused either by intracranial lesions or by optic neuropathy.
Intracranial cases are often lumped as burn encephalopathy, a term that specifies neither a characteristic neuropathological lesion nor a particular set of symptoms.1- 7 Infection, metabolic disturbances, and hypoxia are undoubtedly contributing factors in some cases. Although the exact pathogenesis of burn encephalopathy is uncertain, it may develop from scalds, which makes it difficult to blame hypoxia or carbon monoxide inhalation.8- 10 Direct heating of the brain cannot be a contributing factor, because the burns did not necessarily involve the head. In several reported cases, encephalopathy even developed from burns that were not particularly extensive.11
Burn encephalopathy, which is typically heralded by seizures and diminished consciousness, may develop immediately or be delayed for more than a month. Profound and bilateral visual impairment has been reported in some patients. These patients were presumably blind on a cortical basis, but in several instances hydrocephalus may also have been a factor. We have identified only 10 published cases of visual loss from the intracranial complications of burns that were not associated with such confounding conditions as meningitis.4,9,10,12- 14 Unfortunately, most of the case histories were incomplete or contained confusing information. For example, it is unclear how the diagnosis of cortical blindness could have been established in patients described as being in coma. In a few cases, there might also have been mechanical injury, which further confuses the issue of pathogenesis.
Central visual impairment following burns is undoubtedly more common than one would infer from the paucity of published cases, because deficits such as coma would mask visual loss. In addition, victims might be too young to report the symptom. Based on our review of published cases, it appears that central visual loss following burns is a disorder of childhood, can be severe, can be caused by scalds or flame burns, can appear after a delay of several weeks, is accompanied by other neurological symptoms, and in some cases provides a remarkable opportunity for complete recovery. The apparent paucity of adult cases defies explanation. Fortunately, the incidence of burn encephalopathy seems to be decreasing.6
Mooren15 was the first to report an optic neuropathy after cutaneous burns, a complication that he considered by no means rare. He also commented that neuropathy sometimes followed minor burns. Peripapillary hemorrhages were a common feature. His patients exhibited a great capacity for recovery; however, he did mention 1 case of severe bilateral loss of vision following superficial leg burns in which recovery did not occur. We found 10 published cases of optic neuropathy or neuroretinopathy ascribable to burns (Table 1).16- 24 Like the central cases described previously, visual loss followed scalds or flame burns, was severe and bilateral, could appear after a delay of weeks (average delay, 3 weeks), and sometimes recovered. Unlike the central cases, optic neuropathy occurred in young adults and adolescents as well as in children. Seven of the patients were men between the ages of 17 and 25 years. In most cases the burns were deep, extensive, and involved the face. Half of the patients were otherwise neurologically normal at the time their visual impairment became evident. Seven patients had disc edema and either a hemorrhagic retinopathy or retinal edema. In 2 cases the optic discs initially appeared normal, and in 1 case they were described as pale. We found optic atrophy in our 2 patients, but these examinations were not performed until months after their loss of vision. The preservation of our first patient's color vision despite optic neuropathy remains unexplained.
Many burned patients have respiratory, infectious, and metabolic complications and receive multiple medications. In light of the multiplicity of factors, it is impossible to identify with certainty the exact cause of the optic neuropathy that follows thermal burns, either in our cases or in those from the literature. However, the occurrence of optic neuropathy after scalds makes it unlikely that hypoxia or carbon monoxide inhalation could be responsible. The delayed onset and the remarkable capacity for recovery observed in some cases do not support an anoxic neuropathy. One possible mechanism is a toxic optic neuropathy from one of the medications. For example, hexachlorophene, which can cause edema of myelin, was once widely used to treat burns.25,26 It or another drug might have played a role in certain cases. Hypotension, especially if potentiated by anemia, could cause an ischemic optic neuropathy. Although hypotension was not documented in these cases, it might well have occurred. Because the face was burned in both of our patients and in at least 8 of the 10 published cases, it is possible that there was a direct thermal effect on the optic nerve or retina.
Although it would be difficult to reconcile with the retinal findings in some cases, another possibility is that visual loss resulted from demyelination mediated by a toxin released from burned skin. Demyelination would allow for restitution of vision. Williams23 described the autopsy findings in a patient who lost vision 15 days after being burned and who died 25 days later. In addition to subacute necrotizing lesions in the brain proper, there was extensive demyelination in the anterior visual pathways. Demyelinative lesions have been found in the brain at autopsy in several other cases, which raises the possibility that cutaneous burns are capable of inducing a demyelinating optic neuropathy.1,27,28 Some authors have theorized that the lesions might be caused by the release of a neurotoxin from burned skin.28- 30 A circulating neurotoxin could explain the case reported by Resch and Sullivan,24 in which a patient, despite being blind, had no lesions of the eye, brain, or optic nerve when autopsied.
Patients who have suffered flame burns or scalding of the skin may develop bilateral optic neuropathy, usually with severe visual loss but a capacity for spontaneous recovery. Retinal hemorrhages and edema may be present. Visual loss may develop immediately or after a delay and need not be accompanied by neurological symptoms. The pathogenesis of the neuropathy has yet to be established, but in some cases it may result from demyelination.
Corresponding author: Simmons Lessell, Department of Ophthalmology, Harvard Medical School and the Massachusetts Eye and Ear Infirmary, 243 Charles St, Boston, MA 02114.
Unsöld AS, Rizzo JF, Lessell S. Optic Neuropathy After Burns. Arch Ophthalmol. 2000;118(12):1696-1698. doi: