Atypical Leber Hereditary Optic Neuropathy: 18 Year Interval Between Eyes

Peripapillary retinal nerve fibre layer thinning, perfusion changes and optic neuropathy in carriers of Leber hereditary optic neuropathy-associated mitochondrial variants

BACKGROUND

We investigated Leber hereditary optic neuropathy (LHON) families for variation in peripapillary retinal nerve fibre layer thickness and perfusion, and associated optic nerve dysfunction.

METHOD

A group of LHON-affected patients (n=12) and their asymptomatic maternal relatives (n=16) underwent examination including visual acuity (VA), visual-evoked-potential and optic nerve imaging including optical coherence tomography (OCT) and OCT angiography of the peripapillary retinal nerve fibre layer (RNFL). A control sample was also examined (n=10). The software imageJ was used to measure perfusion by assessing vessel density (VD), and statistical software 'R' was used to analyse data.

RESULTS

The LHON-affected group (n=12) had significantly reduced peripapillary VD (median 7.9%, p=0.046). Overall, the LHON asymptomatic relatives (n=16) had no significant change in peripapillary VD (p=0.166), though three eyes had VD which fell below the derived normal range at 6% each, with variable VA from normal to blindness; LogMAR median 0, range 0-2.4. In contrast, RNFL thickness was significantly reduced in the LHON-affected group (median 51 µm, p=0.003), and in asymptomatic relatives (median 90 µm, p=0.01), compared with controls (median 101 µm). RNFL thinning had greater specificity compared with reduced perfusion for optic nerve dysfunction in asymptomatic carriers (92% vs 66%).

CONCLUSION

Overall, reduced peripapillary retinal nerve fibre layer perfusion was observed in those affected by LHON but was not reduced in their asymptomatic relatives, unlike RNFL thinning which was significantly reduced in both groups versus controls. The presence of RNFL changes was associated with signs of optic neuropathy in asymptomatic relatives.

Leber Hereditary Optic Neuropathy (LHON) in Patients with Presumed Childhood Monocular Amblyopia

BACKGROUND

Most Leber hereditary optic neuropathy (LHON) cases are bilateral and sequential; however, there are rare unilateral examples, or those in which the delay of onset of vision loss between one and the other eye is longer. In the case of presumed childhood amblyopia in one eye, vision loss in the good eye may be the only symptom of bilateral disease, which was unnoticed in the previously amblyopic eye, or a preexisting episode of LHON in the "amblyopic" eye. The clinical decision in such cases may be difficult and suggestive of other forms of atypical optic neuropathy until confirmed by genetic testing.

CASE SERIES

We present three genetically confirmed (MT-ND1:m.3700G>A, MT-ND6:m14484 T>C, and MT-ND4:m.11778G>A) patients with subacute vision loss in the previously good eye, with the other eye believed to be amblyopic from childhood and their features different from what would be expected in true amblyopia. In all, electrophysiology testing showed a bilaterally reduced amplitude of PERG with low VEP P100 wave amplitudes and prolonged peak time in both eyes, also unusual for amblyopia. During follow-up, the pallor of the optic discs progressed in all eyes. Significant thinning of the peripapillary retinal nerve fiber layer (pRNFL; retinal nerve fiber layer around the optic disc) and ganglion cell complex (GCC) in the macular region was present. All three patients had a peculiar history. The first patient was treated for presumed hyperopic amblyopia that did not improve since childhood, experienced visual loss in the good eye at the age of 17, and was negative for the three typical LHON mutations. Extended testing confirmed an atypical pathogenic variant MT-ND1:m.3700G>A in homoplasmy. The second patient with presumed strabismic amblyopia had an unusual presentation of vision loss only at the age of 61, and after the exclusion of other causes, a typical MT-ND4:m.11778G>A pathogenic variant was found in homoplasmy. The third case was peculiar as he had presumed strabismic amblyopia since childhood and had some degree of disc pallor in the amblyopic eye upon presenting with loss of vision in the good eye at the age of 21, and a typical pathogenic variant m14484 T>C, p.Met64Val was subsequently confirmed. However, one year after disease onset, he started to experience significant spontaneous functional improvement in the non-amblyopic up to 1.0 Snellen whilst improvement in the presumed amblyopic eye was modest, suggesting preexisting amblyopia. This interestingly extensive improvement was carefully followed by electrophysiology as well as visual acuity and fields.

CONCLUSIONS

This report shows three different scenarios of presentation of LHON in patients with presumed uniocular amblyopia from childhood. In such cases, the diagnosis may be difficult, and detailed structural and functional evaluation of the optic nerve head is necessary to assess whether an earlier LHON episode was misdiagnosed as amblyopia or whether LHON presented bilaterally on both eyes whilst only being noticed in the previously good eye.

Optic Nerve Structural and Functional Changes in LHON-Affected and Asymptomatic Maternal Relatives: Association with H and HV Mitochondrial Haplogroups

Leber Hereditary Optic Neuropathy (LHON) affects a minority of carriers of causative mitochondrial DNA mutations. We investigated a cohort of patients with LHON, including m.11778G>A, m.3460G>A, m.14484T>C and DNAJC30 c.152A>G variants, and their asymptomatic maternal carrier relatives for additional potential associations with vision loss. We assessed visual acuity, optical coherence tomography (OCT) of the peripapillary retinal nerve fibre layer (RNFL), visually evoked potential including P-100 latency, and full mitochondrial genome sequencing. Comparison was made with a reference standard for OCT; European Descent, Heidelberg Engineering ©; and electrophysiology measurements with in-house normative ranges. RNFL was thinned overall in LHON patients (n = 12); median global RNFL −54 μm in the right eye (RE) and −50 μm in the left eye (LE) versus normal, and was found to be normal overall in asymptomatic carriers at +1 μm RE and −2 μm LE (n = 16). In four asymptomatic carriers there was RNFL thinning found either unilaterally or bilaterally; these cases were associated with isolated delay in P-100 latency (25%), delay and reduced visual acuity (50%), or reduced visual acuity without P-100 latency delay (25%). Optic nerve dysfunction was associated with mitochondrial haplogroup H and HV, versus non-H haplogroups, in the asymptomatic carriers (Fisher’s exact test, p = 0.05). Our findings suggest that optic nerve abnormalities may be identified in asymptomatic LHON mitochondrial mutation carriers, which may be associated with optic nerve dysfunction. For asymptomatic carriers these findings were associated with mitochondrial haplogroup H and HV.

Childhood-Onset Leber Hereditary Optic Neuropathy-Clinical and Prognostic Insights

PURPOSE

To investigate the clinical and molecular genetic features of childhood-onset Leber hereditary optic neuropathy (LHON) to gain a better understanding of the factors influencing the visual outcome in this atypical form of the disease.

DESIGN

Retrospective cohort study.

METHODS

We retrospectively included 2 cohorts of patients with LHON with onset of visual loss before the age of 12 years from Italy and the United Kingdom. Ophthalmologic evaluation, including best-corrected visual acuity, orthoptic evaluation, slit-lamp biomicroscopy, visual field testing, and optical coherence tomography, was considered. Patients were classified based on both the age of onset and the pattern of visual loss.

RESULTS

A total of 68 patients were stratified based on the age of onset of visual loss: group 1 (<3 years): 14 patients (20.6%); group 2 (≥3 to <9 years): 27 patients (39.7%); and group 3 (≥9 to ≤12 years): 27 patients (39.7%). Patients in group 2 achieved a better visual outcome than those in group 3. Patients in groups 1 and 2 had better mean deviation on visual field testing than those in group 3. The mean ganglion cell layer thickness on optical coherence tomography in group 2 was higher than those in groups 1 and 3. Patients were also categorized based on the pattern of visual loss as follows: Subacute Bilateral: 54 patients (66.7%); Insidious Bilateral: 14 patients (17.3%); Unilateral: 9 patients (11.1%); and Subclinical Bilateral: 4 patients (4.9%).

CONCLUSIONS

Children who lose vision from LHON before the age of 9 years have a better visual prognosis than those who become affected in later years, likely representing a "form frustre" of the disease.

Atypical Leber hereditary optic neuropathy with a 34-year interval between vision loss in both eyes

Purpose

Leber hereditary optic neuropathy (LHON) is an inherited mitochondrial disease characterized by painless vision loss affecting both eyes. The disease usually develops in both eyes within weeks to months of onset. We report a case of LHON who presented with unilateral vision loss in childhood with an interval of more than 30 years between vision loss in the two eyes.

Observation

A 43-year-old man presented with a 1-month history of vision loss in his right eye. At 9 years of age, his visual acuity in the left eye declined, and he had been treated with glaucoma eyedrops bilaterally at his eye clinic. At his first visit to our hospital, his BCVA was 0.15 in the right eye and 0.1 in the left eye, and critical flicker frequency was 16 Hz in the right eye and 15 Hz in the left eye, and he was negative for a relative afferent pupillary defect. The Goldman visual field showed central scotoma in both eyes. Fundus examination revealed slight redness of the right optic disc with meandering retinal small vessels, and the left optic disc had a slight pallor. Fluorescein angiography could not be performed because of liver dysfunction. OCT showed prominent bilateral thinning of the RNFL and retinal ganglion cell layer. Enhancement of the optic nerve was not apparent on orbital gadolinium-enhanced magnetic resonance imaging. Hematologic analysis revealed macrocytic anemia and low levels of vitamin B12 and folate. His mother had a presumptive diagnosis of LHON but did not receive genetic testing. A male cousin also had severe vision loss. Based on the likely family history of LHON, we performed genetic testing, which revealed the 11778 mitochondrial point mutation associated with this condition.

Conclusion and importance

We report a case of LHON with 34 years interval in vision loss in the fellow eye. LHON may develop in the second eye decades after its onset in the first. Detailed medical interviews and scrutiny, such as examination of family history, are warranted in consideration of LHON.

Cyclosporine A does not prevent second-eye involvement in Leber's hereditary optic neuropathy

BACKRGROUND

Evaluation of the efficacy of oral cyclosporine A as a prophylactic agent in preventing second-eye involvement in Leber's hereditary optic neuropathy (LHON) in a prospective, open-label, non-randomized, multicenter pilot study. Only LHON patients aged 18 years or more, with confirmed primary mitochondrial DNA mutations and strictly unilateral optic neuropathy occurring within 6 months prior to enrolment, were included in the study. All these patients, receiving treatment with oral cyclosporine (Neoral®, Novartis) at 2.5 mg/kg/day, were examined at three-month intervals for a year. The primary endpoint was the best corrected visual acuity in the unaffected eye; the secondary endpoints were the best corrected visual acuity in the first eye affected, the mean visual field defect on automated perimetry, the thickness of the perifoveal retinal ganglion cell inner plexiform layer, and the thickness of the peripapillary retinal nerve fiber layer in both eyes.

RESULTS

Among the 24 patients referred to our institution with genetically confirmed LHON, between July 2011 and April 2014, only five patients, four males and one female, fulfilled the inclusion criteria. Age at enrolment ranged from 19 to 42 years (mean: 27.2 years; median: 26 years), four patients harbored the m.11778G > A pathogenic variant, and one the m.14484 T > C pathogenic variant. The time-interval between the onset of symptoms and inclusion in the study ranged from 7 to 17 weeks (mean: 11.8 weeks; median: 9 weeks). Despite treatment with oral cyclosporine A, all patients eventually experienced bilateral eye involvement, occurring within 11-65 weeks after the initiation of treatment. Over the study time period, the average best corrected visual acuity worsened in the first eye affected; by the end of the study, both eyes were equally affected.

CONCLUSIONS

Oral cyclosporine, at 2.5 mg/kg/day, did not prevent second-eye involvement in patients with strictly unilateral Leber's hereditary optic neuropathy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02176733 . Registrated June 25, 2014.

Gene Therapy for Leber Hereditary Optic Neuropathy: Low- and Medium-Dose Visual Results

PURPOSE

To determine the effects of AAV2(Y444,500,730F)-P1ND4v2 in patients with Leber hereditary optic neuropathy (LHON).

DESIGN

Prospective open-label, unilateral single-dose, intravitreal injection of AAV2(Y444,500,730F)-P1ND4v2 per participant.

PARTICIPANTS

Fourteen patients with visual loss and mutated G11778A mitochondrial DNA.

METHODS

Intravitreal injection with the gene therapy vector AAV2(Y444,500,730F)-P1ND4v2 into 1 eye. Six participants with chronic bilateral visual loss lasting more than 12 months (group 1), 6 participants with bilateral visual loss lasting less than 12 months (group 2), and 2 participants with unilateral visual loss (group 3) were treated. Nine patients had at least 12 months of follow-up. Clinical testing included visual acuity, visual fields, optical coherence tomography, pattern electroretinography, and neuro-ophthalmic examinations. Generalized estimating equation methods were used for longitudinal analyses.

MAIN OUTCOME MEASURE

Loss of visual acuity.

RESULTS

For groups 1 and 2, month 12 average acuity improvements with treatment relative to baseline were 0.24 logarithm of the minimum angle of resolution (logMAR). Fellow eyes had a 0.09-logMAR improvement. A post hoc comparison found that at month 12, the difference between study eye minus fellow eye improvement in group 2 patients of 0.53 logMAR was greater than that observed in our prior acute natural history patients of 0.21 logMAR (P = 0.053). At month 18, the difference between study eye minus fellow eye improvement in our acute group 2 gene therapy patients of 0.96 was more than that observed in our prior acute natural history patients (0.17 logMAR; P < 0.001). Two patients demonstrated asymptomatic uveitis that resolved without treatment. Optical coherence tomography of treated eyes showed an average temporal retinal nerve fiber layer thickness of 54 μm before injection and 55 μm at month 12. For fellow eyes before injection, it was 56 μm, decreasing to 50 μm at month 12 (P = 0.013). Generalized estimating equations suggested that PERG amplitudes worsened more in treated eyes than in fellow eyes by approximately 0.05 μV (P = 0.009 exchangeable). No difference between eyes in outcomes of other visual function measures was evident.

CONCLUSIONS

Allotopic gene therapy for LHON at low and medium doses seems to be safe and does not damage the temporal retinal nerve fiber layer, opening the door next for testing of the high dose.

Lateral thinking - Interocular symmetry and asymmetry in neurovascular patterning, in health and disease

No biological system or structure is likely to be perfectly symmetrical, or have identical right and left forms. This review explores the evidence for eye and visual pathway asymmetry, in health and in disease, and attempts to provide guidance for those studying the structure and function of the visual system, where recognition of symmetry or asymmetry may be essential. The principal question with regards to asymmetry is not 'are the eyes the same?', for some degree of asymmetry is pervasive, but 'when are they importantly different?'. Knowing if right and left eyes are 'importantly different' could have significant consequences for deciding whether right or left eyes are included in an analysis or for examining the association between a phenotype and ocular parameter. The presence of significant asymmetry would also have important implications for the design of normative databases of retinal and optic nerve metrics. In this review, we highlight not only the universal presence of asymmetry, but provide evidence that some elements of the visual system are inherently more asymmetric than others, pointing to the need for improved normative data to explain sources of asymmetry and their impact on determining associations with genetic, environmental or health-related factors and ultimately in clinical practice.

Leber Hereditary Optic Neuropathy with Interval of Visual Loss Greater Than 12 Months

A 28-year-old man presented with severe left visual loss and normal right visual acuity. The left fundus examination showed temporal pallor and complete absence of the nerve fibre layer (NFL) of papillomacular bundle. Right fundus examination showed focal loss of inferotemporal NFL. Magnetic resonance and serum aquaporin-4 antibody were negative. After 14 months of the initial visual involvement, the patient suffered subacute visual loss in contralateral eye. Genetic study revealed the 11778 point mitochondrial DNA (mtDNA) mutation associated with Leber hereditary optic neuropathy (LHON). Although very rare, interval of involvement of second eye greater than 12 months can occurs in LHON. Detailed optic nerve examination and careful interpretation of optical coherence tomography (OCT) printout support the diagnosis.