Retinal nerve fiber layer evaluation by optical coherence tomography in unaffected carriers with Leber's hereditary optic neuropathy mutations.
OBJECTIVE
To study retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT) in unaffected carriers with Leber's hereditary optic neuropathy (LHON) mutations.


METHODS
Cross-sectional study.


METHODS
Sixty-six unaffected carriers (44 females and 22 males) were analyzed and compared with an age-matched control group of 70 patients (40 females and 30 males). The statistical analysis was performed after grouping both the patients and the control group on the basis of gender and, for unaffected carriers only, mitochondrial DNA mutation.


METHODS
The Fast RNFL Thickness (3.4) scan acquisition protocol was used.


METHODS
Retinal nerve fiber layer thickness as measured by OCT.


RESULTS
With respect to the control group, unaffected male carriers showed a thicker RNFL in the temporal and inferior quadrants and in the 360 degrees average measurement (P = 0.025, P = 0.03, and P = 0.018, respectively). These differences reached statistical significance in subjects carrying the 11778 mutation, whereas only a trend was detected in those with the 3460 mutation. Unaffected female carriers had an increased thickness in the temporal quadrant when compared with the control group (P = 0.003) and no differences in the other measurements. The increase in temporal sectors was statistically significant in females with the 11778 mutation, whereas a trend was detected in those with the 3460 mutation.


CONCLUSIONS
A thickening of the temporal fibers was detected in all subgroups of unaffected carriers. This is the first evidence indicating the preferential involvement of the papillomacular bundle in subclinical LHON. This notion previously was based on the early loss of fibers from the temporal quadrant in acute LHON and the selective loss of small-caliber fibers at histopathology. Our study also revealed that males have a more diffuse involvement than females.
Savini
Giacomo
G
Centro di Oftalmologia Salus, Bologna, Italy. salus@eyeproject.com <salus@eyeproject.com>
Barboni
Piero
P
Valentino
Maria Lucia
ML
Montagna
Pasquale
P
Cortelli
Pietro
P
De Negri
Anna Maria
AM
Sadun
Federico
F
Bianchi
Stefania
S
Longanesi
Lora
L
Zanini
Maurizio
M
Carelli
Valerio
V
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003430:Cross-Sectional Studies; D004272:DNA, Mitochondrial / Q000235:genetics; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D020022:Genetic Predisposition to Disease; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009412:Nerve Fibers / Q000473:pathology*; D029242:Optic Atrophy, Hereditary, Leber / Q000175:diagnosis / Q000235:genetics*; D010375:Pedigree; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence
D004272:DNA, Mitochondrial