Re: Rönnbäck et al.: Imaging of the macula indicates early completion of structural deficit in autosomal-dominant optic atrophy (Ophthalmology 2013;120:2672–7)

Acetazolamide Reduces Retinal Inner Nuclear Layer Thickness in Microcystic Macular Edema Secondary to Optic Neuropathy

Optic neuropathy (ON) is commonly complicated by microcystic macular edema (MME), that is, small vertical cystoid spaces in the inner nuclear layer (INL) of the macula. We performed a retrospective consecutive case series of 14 eyes from 11 patients with ON and MME that were treated with oral acetazolamide, acting on cellular water transport. Contralateral eyes without MME were used as controls. Segmentation of images obtained with OCT was used to determine changes of individual retinal layer thickness during treatment. Retinal INL thickness consistently decreased in all eyes after 2–3 weeks of treatment. Recurrence of MME was observed after treatment cessation. No significant change of retinal thickness was found in contralateral unaffected eyes. Visual function did not change with treatment. Acetazolamide significantly improved the MME in eyes with ON. However, visual function did not. Acetazolamide is a treatment option for MME associated with ON but without an impact on the visual function.

Characterization of two novel intronic OPA1 mutations resulting in aberrant pre-mRNA splicing

BACKGROUND

We report two novel splice region mutations in OPA1 in two unrelated families presenting with autosomal-dominant optic atrophy type 1 (ADOA1) (ADOA or Kjer type optic atrophy). Mutations in OPA1 encoding a mitochondrial inner membrane protein are a major cause of ADOA.

METHODS

We analyzed two unrelated families including four affected individuals clinically suspicious of ADOA. Standard ocular examinations were performed in affected individuals of both families. All coding exons, as well as exon-intron boundaries of the OPA1 gene were sequenced. In addition, multiplex ligation-dependent probe amplification (MLPA) was performed to uncover copy number variations in OPA1. mRNA processing was monitored using RT-PCR and subsequent cDNA analysis.

RESULTS

We report two novel splice region mutations in OPA1 in two unrelated individuals and their affected relatives, which were previously not described in the literature. In one family the heterozygous insertion and deletion c.[611-37_611-38insACTGGAGAATGTAAAGGGCTTT;611-6_611-16delCATATTTATCT] was found in all investigated family members leading to the activation of an intronic cryptic splice site. In the second family sequencing of OPA1 disclosed a de novo heterozygous deletion c.2012+4_2012+7delAGTA resulting in exon 18 and 19 skipping, which was not detected in healthy family members.

CONCLUSION

We identified two novel intronic mutations in OPA1 affecting the correct OPA1 pre-mRNA splicing, which was confirmed by OPA1 cDNA analysis. This study shows the importance of transcript analysis to determine the consequences of unclear intronic mutations in OPA1 in proximity to the intron-exon boundaries.

The prevalence of microcystic macular changes on optical coherence tomography of the macular region in optic nerve atrophy of non-neuritis origin: a prospective study

BACKGROUND

Microcystic macular changes, also called microcystic macular oedema, have recently been reported in patients with multiple sclerosis, particularly after optic neuritis. But it has since emerged that the finding is not specific for optic neuritis. This study was designed to prospectively investigate the prevalence of microcystic perifoveal changes in patients with optic atrophy not due to optic neuritis.

METHODS

A prospective, cross-sectional study including 54 patients with a history of optic atrophy and 54 healthy control subjects. Spectral domain optical coherence tomography (SD-OCT) was used to scan the macular area and to measure the peripapillar retinal nerve fibre layer thickness. Scanning laser ophthalmoscopy (SLO) was used for imaging of the macular area.

RESULTS

Microcystic macular changes were present in 11/54 patients (20.4%), 17/90 eyes with optic atrophy (18.9%) and absent in the normal eyes of patients with monocular optic atrophy and all healthy control eyes. No correlations were found with the age, duration of optic atrophy or severity of optic atrophy. Besides the known perifoveal (semi) circular abnormal reflexes on SLO imaging, we also noticed a more patchy pattern of low SLO reflections in some patients with optic atrophy.

CONCLUSIONS

Microcystic macular changes are a frequent observation in patients with optic atrophy of another cause than optic neuritis. The cause of these abnormalities remains a matter of debate. It is important for clinicians to recognise these macular changes and to realise that the cause may lie remotely away from the macula.