DJO | Digital Journal of Ophthalmology


46-year-old gentleman with bilateral blurry vision and photophobia for 6 months. Digital Journal of Ophthalmology 2004 Volume 10, Number 4 February 3, 2004	Printer Friendly

Rishi Singh, M.D. \| Massachusetts Eye and Ear Infirmary Simmons Lessell, M.D. \| Massachusetts Eye and Ear Infirmary

History
The patient is a 46-year-old male with complaints of bilateral blurry vision and photophobia for 6 months. He states that he was in his usual state of eye health 6 months prior when he began to develop progressive blurring of both eyes, which was constant throughout the day. He initially presented an optometrist 1 month after his symptoms began and he was diagnosed and treated for presbyopia. Over this time period he also noticed that colors looked washed out. While at a Red Sox game he remarked, "the dirt and the grass of the field all looked the same." Past Medical History: Hypertension Past Ocular History: Presbyopia Current Medications: Denies Allergies: Denies Occupation: House Father Habits: Smokes 5-6 cigars per day and consumes 6 alcoholic beverages per day.

Examination
Visual acuity 16/30 OU Pupillary examination - round reactive, no afferent defect detected. Ocular Motility - Full ductions and saccades. Color Vision - able to read the control plate only in both eyes. Tensions - 17 mm Hg OD, 21 mm Hg OS Fundus Examination - please see photos

OD Fundus Photo Presenting Fundus Photo OD

OS Fundus Photo Presenting OS Fundus Photo

Ancillary Testing
Pathology Ancillary Testing: Goldmann Visual Field Testing - Bilateral ceco-central scotomas Normal Hearing Hemoglobin - 13.5 g/dl (low) Hematocrit - 39.4 % (low) White cells - 10.1 (normal) RPR - non-reactive Vitamin B12 - 466 pg/ml (normal) Folic Acid 7.4 ng/ml (normal) PCR analysis for mitochondrial DNA mutations found in Lebers Hereditary Optic Neuropathy - Negative for any mutation

OS Visual Field Presenting OS Visual Field

OD Visual Field Presenting OD Visual Field

Treatment
Patient was started on hydroxyocobalomin injections 1x/week. Follow-up examinations revealed visual acuity of 16/15 OU, and resolutions of the central scotomas and dyschromatopsia OU. He continued to smoke during the treatment regimen.

OS Visual Field OS Visual field 2 months into treatment

OD Visual Field OD Visual Field 2 months into treatment

OS Visual Field OS Visual Field 6 months into treatment

OD Visual Field OD Visual Field 6 months into treatment

Differential Diagnosis
1. Psychogenic (hysterical or malingered) 2. Retinopathies may cause metamorphopsia, night blindness, photisms, and delayed glare recovery 3. Neural causes Dominantly inherited (Kjer's) Mitochondrially inherited (Leber's) Inflammatory/Demyleinating optic neuropathies Infiltration or compression Pernicious anemia

Diagnosis and Discussion
Tobacco Amblyopia typically occurs in patients who are pipe and cigar smokers and the etiology is unknown. There has been a marked decline in the incidence of Tobacco Amblyopia since the advent of genetic testing for Leber hereditary optic neuropathy as it was felt that many patients were initially misdiagnosed. There is a large differential in patients with bilateral ceco-central scotomas including nutritional optic neuropathy (B12 deficiency), Leber's hereditary optic neuropathy, Kjers dominant optic atrophy, cilioretinal artery occlusion, infectious optic neuropathy such in syphilis, and psychogenic loss. A multifactoral etiology is postulated since only a minority of patients who smoke develop this disease and no dose dependent correlation has been discovered. Cyanide toxicity from cigarette smoke and relative malabsorption of Vitamin B12 from the gut have been postulated as mechanisms, but not proven (1). Alcohol has also been postulated to be a co-factor in this disease process, however, alcohol alone has not been proven to be toxic to the visual pathways. Low serum vitamin B12 levels have been suspected as one factor (2). Patient with Tobacco Amblyopia can have any level of visual acuity. It presents as a painless, progressive bilateral optic neuropathy with visual loss, dyschromatopsia, and ceco-central scotomas on visual field testing. Nystagmus, ptosis, and ophthalmoplegia can be present if the patient is experiencing Wernicke's encephalopathy. The optic nerve appears pale and the rest of the fundus usually appears normal. An evanescent peripapillary retinopathy characterized by hemorrhages and dilated, tortuous vessels in the nerve fiber layer has been described in a case series (3). Treatment consists of hydroxocobalomin injections or oral replacement therapy and cessation of smoking. Nonetheless, patients such as the one presented here who have continued to smoke and who receive vitamin B12 do improve. Previous studies have shown that hydroxocobalomin is superior to cobalomin alone in the treatment of these patients. Administration of the medications with an internist and close follow up with visual field testing is recommended when following these patients.

References
1. Freeman AG: Optic neuropathy and chronic cyanide intoxication: A review. J Soc Med 81:103, 1988. 2. Foulds WS, Chisholm IA, Bronte-Stewart JM, et al: Vitamin B12 absorption in tobacco amblyopia. Br J Ophthalmol 53:393, 1969. 3. Frisén L: Fundus changes in acute nutritional amblyopia. Arch Ophthalmol 101:577, 1983.