Methodology & Case Description
This is a retrospective case series of ten patients who presented at a tertiary eye care, with clinical features suggestive of an Optic neuropathy. The patients were evaluated & diagnosed on the basis of clinical judgement & investigations.
Case 1
A 43-year-old female patient presented with complaint of dimness of vision left eye since 1 month. BCVa RE-6/6, LE- 6/60, RE-disc edema along nasal margin, LE - temporal pallor. Visual fields - LE unequivocal & RE total loss of right half, respecting vertical meridian. Suspecting Foster Kennedy syndrome, patient was further investigated & found to have a bilateral frontal space occupying lesion, for which she underwent bifrontal craniectomy with supraorbital osteotomy & excision of SOL which was adherent to optic chiasma. Biopsy confirmed olfactory groove sarcoidosis.
Case 2
61 year old female, diabetic & hypertensive, presented with complain of decreasing vision left eye since 10 days. BCVa, RE-6/9 & LE- 6/36p, RAPD in LE , IOP 19 mmHg BE, .75 & .85 cupping RE & LE respectively with prominent disc pallor. LE showed very advanced visual field defect, but RE field clinched the diagnosis of neurological fields. Investigations revealed pituitary microadenoma compressing left optic nerve & crossing fibres of right eye along optic chiasma, for which she underwent surgery with a successful removal of the tumor.
Case 3
A 53 year old male, hypertensive, presented with complaint of decreased vision. BE had shallow anterior chamber, occludable angles, BCVa RE-6/12p, LE-6/9, IOP 18 & 19 mmHg respectively & CCT of 490 microns BE, RE C:D- . 7 & LE C:D -.5 prominent temporal pallor of both optic nerve heads, left homonymous hemianopia. Field defects appeared to break through to the opposite side with a questionable superior arcuate form. He gave a history of left hemeperesis 4 years back with CT brain showing retrochiasmatic right hemorrhagic infarct.
Case 4
A 24-year-old female patient presented with complaint of dimness of vision both eyes since 1 year, tinnitus & some hearing loss. BCVa 6/60 OU, IOP 17 mmHg, normal ODs with .3 cupping, open angles. She had been diagnosed as a malingerer elsewhere, in view of all normal findings, including a normal color vision test. We did Visual field test, which revealed a central, para central field defect. Suspecting some form of optic neuropathy, a VEP was advised, which showed bilateral prolonged P-100 latencies, confirming an optic neuropathy of a non-glaucomatous type, for which she is being further investigated.
Case 5
A 53 year old male patient presented with complaints of progressive dimness of vision both eyes & headache since few months , but a sudden & gross dimness of vision RE , followed soon in LE 20 days back. His Vn both eyes was CF 1 Feet, IOP-15 & 11 mmHg RE, LE respectively, open angles & C:D .75 RE, .3 LE , with disc pallor, almost total color vision defect ,marked field defects both eyes. After an intensive questioning & history taking, he revealed heavy alcohol intake daily since many years. A diagnosis of toxic optic neuropathy/atrophy, was made.
Case 6
A 50 year old diabetic patient presented with complaint of discharge in left eye. His BCVA BE was 6/5, N-6, LE showed RAPD, IOP OU-19/ 20 mmHG respectively, RE optic disc normal, LE showed disc edema . Color vision BE- normal, Visual fields RE- Normal, LE showed early/ relative inferior altitudinal field defect, uncontrolled blood sugar levels. A diagnosis of non arteritic anterior ischemic optic neuropathy [NA-AION] was made.
Case 7
A 55 year old male patient presented with complains of sudden & gross dimness of vision RE followed by some dimness of vision LE since 1 year. BCVA RE 6/60, LE 6/18,IOP- 17 mmHg .RE- Disc gliosis with pallor, LE disc - temporal pallor, with both eyes cupping not clear. RE showed gross field defect, LE altitudinal field defect. ESR -22,borderline hyperlipidemia, CRP normal, other features like jaw claudication were absent & patient denied temporal artery biopsy . A diagnosis of Arteritic anterior ischemic optic neuropathy was made [A-AION].
Case 8
A 42 year-old female patient came for a regular glass prescription. BCVa 6/6, N/6, uneventful ocular exam, except a bilateral disc edema. On questioning she told that she was a patient of Benign intracranial hypertension under long term diuretic treatment. Visual fields showed a classic enlargement of blind spot with peripheral constriction of field.
Case 9
A 49 year old female patient presented with complain of pain right eye with decreased vision since few days. BCVA RE 2/60, RAPD, total color vision loss, & disc hyperemic & edematous. LE normal with BCVA 6/6. Visual fields LE- normal, while RE showed a gross irregular field defect, Borderline neutrophilia. MRI brain & spinal chord did not show MS plaques. Optic neuritis was diagnosed & treated with high dose systemic steroids, with vision & fields returning to normal.
Case 10
A 40-year-old male patient presented with complaint of gradual & gross dimness of vision since last 15 years. Vision BE 1/60, IOP 18 mmHg, defective color vision. Optic discs showed disc pallor & peripapillary telangiectasis & Visual fields showed irregular constriction. MRI plain & contrast Brain & orbit - T2 hyperintense signal seen in optic nerve & chiasma. VEP & CSF analysis - normal. Suspecting Leber’s hereditary optic neuropathy, a genetic study was conducted for mitochondrial gene variation evaluation, which showed a homoplasmic missense variation in the MT-ND4 gene, mutations of which have been reported to be associated with LHON.
Discussion
In case 1 a timely diagnosis with an optimum surgical intervention saved the patient from systemic & ocular morbidity, with an excellent visual recovery in LE from 6/60 pre-op to 6/5 post –op. Case 2 was being treated for glaucoma elsewhere. Resection of tumor unfortunately lead to collateral damage, with loss of vision in the better seeing eye, which could have been avoided / mitigated with a timely diagnosis & intervention. In Case 3 neurological diagnosis was clear but in view of the occludable angles, thin CCT, antiglaucoma medication was also started, as disc & field picture was inconclusive in making a confirmed diagnosis of a concurrent glaucoma. In cases 1-3 Visual field analysis confirmed a neurological pathology.1 Case 4 – Its important to thoroughly investigate a patient before labeling them as malingerer to avoid missing a potentially vision/ life threatening pathology.2 Case 5 Toxic optic neuropathy is often under /late diagnosed, with patients presenting with painless, progressive, bilateral symmetrical visual loss, papillomacular bundle damage, central or cecocentral scotoma, and reduced color vision, where both toxic and nutritional factors play a synergistic role. 3 Case 6 & 7 – In NA- AION there is transient non- perfusion / hypoperfusion of ONH circulation in posterior ciliary arteries [PCAs], seen more often in microangiopathy associated with hypertension & Diabetes mellitus, hence usually less severe & extensive ONH damage than A-AION, in which there is thrombotic occlusion of PCAs. Almost half of the N-AION patients can have almost normal Vision & about 40% show spontaneous visual improvement, 4 in sharp contrast to A-AION, where no such recovery is seen. 5 A relative altitudinal defect with RAPD, unilateral disease, good vision & a small cup in other eye were helpful diagnostic criteria for N-AION in case 6. A massive visual loss with no recovery, bilateral involvement, extensive field defect in RE with an absolute inferior altitudinal field defect in LE helped clinch the diagnosis of A-AION in case 7. Absence of systemic sypmtoms like jaw claudication does not rule out the disease. Temporal artery biopsy should be done for confirming the diagnosis.6, 4, 5, 7, 8, 9 History taking & ONH examination, with relevant investigations are crucial, as infrequent or a single episode of transient obscuration of vision, a feature of papilledema, may not be registered by the patients.10 Correlating complaints with clinical picture seen on ONH can confirm a diagnosis of anterior typical optic neuritis. The optic neuritis treatment trial (ONTT) showed that IV methylprednisolone followed by a tapering course of oral prednisone accelerated visual recovery by a few weeks, & , that the presence of asymptomatic white matter lesions on the MRI scan is the strongest predictor for MS.11, 12 LHON presents with simultaneous or sequential painless loss of vision with either an acute or sub-acute onset & defects in color vision.12
