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Neuro-Ophthalmology Newsletter September 2012

Non-arteritic anterior ischemic optic neuropathy can be frustrating to physician and patient alike since no treatment has been shown scientifically to affect the outcome of the disease. Some physicians will treat these patients with corticosteroids in the hope that they may have an impact on recovery. Rebolleda, et al (Graefes Arch Clin Exp Ophthalmol 2012; e-published March 24, 2012), looked at ten eyes in ten patients with AION and treated them with Prednisone 80 mg initially with taper. The results in these patients were compared with 27 randomly selected historical controls. Patients were examined six to eight weeks following onset and six months following onset. The authors found no difference between the two groups in improvement of visual acuity, visual field median deviation, or visual field pattern standard deviation. Nerve fiber layer loss was similar in both groups. Three patients on corticosteroids suffered complications of treatment and one had to discontinue therapy. Two of the patients on Prednisone taper developed AION in the fellow eye within three months of losing vision in the first eye. No complications were noted in the control group. The authors terminated the study early due to the increased risk of complications in the treatment arm. The authors concluded that corticosteroids provided no benefit in visual outcome in AION and that it was associated with a significant risk of serious complications.

 

Adult strabismus patients have a lower quality of life than the general population. Most patients receive appropriate surgical treatment but others may not be medically stable enough to undergo surgery. Hancox, et al (Br J Ophthalmol 2012; 96:838-840), noted that many of these patients receive Botox injections as therapy. The authors retrospectively identified 65 patients who had undergone over 25 Botox injections for long term management were studied using quality of life surveys. 48 patients completed the questionnaire. Analysis of the surveys indicated that patients receiving Botox injections had a similar quality of life score to patients without strabismus and statistically better quality of life compared to patients with strabismus. The authors concluded that Botox was a good choice for therapy in patients who are not candidates for surgrery.

 

Patients with significant carotid artery stenosis are at an increased risk for stroke. Physicians have been looking for screening techniques to noninvasively identify these individuals.  Knecht, et al (Ophthalmology 2012; 119:1244-1249), studied ocular pulse amplitude, the difference in intraocular pressure between diastolic and systolic heartbeat phase readings, as a possible alternative. 67 consecutive patients in for carotid Doppler studies were included in the cohort. The authors compared ocular pulse amplitude in patients with less than 50% occlusion with those with more than 70% occlusion. The authors found a significantly difference in the ocular pulse amplitude in patients with mild stenosis compared to those with severe stenosis. The authors concluded that ocular pulse amplitude shows promise as a safe and economical screening tool for identifying patients at risk for severe carotid artery stenosis.

 

 

Neuro-Ophthalmology Newsletter

Volume IX, Number 9 – September 2012

Case Study

 

Patient IX9 is a 62-year-old woman who noted progressive loss of vision in her right eye. She now could barely see at all out of her right eye. She did not note any problems with her left eye. She had some mild headaches that were frequent. 

 

Her medical history did not indicate any factors that might explain her symptoms.

 

Her ocular history is significant for the problems listed above.

 

Her review of systems is otherwise noncontributory.

 

Her family history was unrevealing.

 

Current medications include over the counter headache medication.

 

Her social history is significant for no tobacco or alcohol consumption.

 

She reported no allergies to medications.

 

On examination, her visual acuity at distance, with correction, was counting fingers only in the right eye and 20/20 in the left eye.  Both pupils measured 5 mm in the dark and 3 mm in the light.  A 4+ right relative afferent pupillary defect was noted.  Humphrey perimetry demonstrated a dense central defect in her right eye and a superior temporal defect outside 10 degrees in her left eye.  Examination of her extraocular motility showed normal motility and alignment.  Slit lamp examination revealed a quiet conjunctiva, clear corneas, deep anterior chambers, and normal irises in both eyes.  Both eyes contained posterior chamber intraocular lenses.  Intraocular pressure measurements were 15 mmHg on her right and 16 mmHg on her left.   Dilation was deferred, again, because of the sleep test.  Her right optic disc showed mild pallor. Her left optic disc was pink and flat.  There was a normal appearance of the macula, retinal blood vessels, and vitreous in both eyes.  A mental status examination revealed her to be alert and oriented x4.

 

Where is the lesion and why did the patient have this particular pattern of visual field changes?

Discussion of Case IX8 from Augusts 2012 Newsletter

 

This patient has diplopia. Whenever you are faced with double vision, a thorough history may point you in the right direction. First of all, she was quite certain that the diplopia was isolated to her right eye. I corroborated this fact when she reported diplopia during visual acuity measurement of her right eye. Since a pinhole alleviated the diplopia and improved her visual acuity to 20/25 from 20/40 in her right eye, her problem had to do with how her eye was focusing.

 

Determining the cause of the diplopia, however, does nothing to explain her motility issues. Although she had decreased ability to abduct, elevate, and adduct both eyes symmetrically, she was well aligned in all directions of gaze. The normal sleep test ruled out the possibility of myasthenia gravis. The pattern did not fit a lesion in the brainstem or cranial nerve. Whenever this particular situation arises, one serious consideration must be chronic progressive ophthalmoplegia (CPEO).

 

CPEO usually presents initially with ptosis. Abnormalities of extraocular movements generally kick in months to years later. The condition results from a mutation in mitochondrial DNA. Patients often have some degree of systemic weakness as well.

 

Early onset CPEO raises concerns about Kearns-Sayre syndrome (KSS). In addition to the usual changes in muscular strength seen with CPEO, these individuals also have a pigmentary retinopathy and cardiac conduction abnormalities, elevated CSF protein, and cerebellar degenerative signs. Unusual components include mental retardation, Babinski sign, hearing loss, seizures, short stature, delayed puberty, and endocrine disorders.

 

The traditional means of diagnosing CPEO and KSS is muscle biopsy to look for characteristic nerve fiber changes and abnormal mitochondria. Polymerase chain reaction testing is available as well to look for mitochondrial DNA mutations.

 

For the record, a muscle biopsy confirmed the diagnosis of CPEO.