Screening for glaucomatous disc changes prior to diagnosis of glaucoma in myocilin pedigrees.
OBJECTIVE
To investigate whether structural differences of the optic nerve head are evident in young people who do not have manifest glaucoma but are known to carry myocilin mutations.


METHODS
A case-control design was adopted. Subjects from Australian pedigrees known to have either the Gln368STOP myocilin mutation (cutoff age, <40 years) or the Thr377Met myocilin mutation (cutoff age, <30 years) were examined for signs of glaucoma. Stereoscopic disc photographs were digitalized. Analysis of the optic disc area, optic cup area, and neuroretinal rim area was performed using digital stereoscopy with a Z-screen. Mutation analysis was conducted using direct sequencing. The t test, corrected for multiple comparison testing, was used in analysis.


RESULTS
A total of 29 myocilin mutation-carrying (case) and 33 mutation-free (control) individuals were reviewed. The mean +/- SD ages were 19.9 +/- 9.0 and 22.1 +/- 9.5 years in the mutation and mutation-free groups, respectively (P = .35). There was no significant difference in intraocular pressure between mutation carriers and noncarriers (P = .44). There were no statistically significant differences in the mean disc, neuroretinal rim, and cup areas between the groups. The mean +/- SD neuroretinal rim area was 1.24 +/- 0.24 mm(2) in the noncarrier group and 1.25 +/- 0.23 mm(2) in the mutation group (P = .46). No notch, nerve fiber layer defect, or neuroretinal rim hemorrhage was noted in any eye examined.


CONCLUSIONS
Although confounded by penetrance and expressivity, no quantified structural difference in the optic nerve head was observed in individuals who had a myocilin mutation prior to the diagnosis of glaucoma.
Bennett
Sonya L
SL
Glaucoma Research Unit and Clinical Genetic Unit, Eye Research Australia, Royal Victorian Eye & Ear Hospital, East Melbourne, Australia.
Hewitt
Alex W
AW
Poulsen
Johan L
JL
Kearns
Lisa S
LS
Morgan
James E
JE
Craig
Jamie E
JE
Mackey
David A
DA
D000328:Adult; D016022:Case-Control Studies; D003598:Cytoskeletal Proteins / Q000235:genetics*; D004252:DNA Mutational Analysis; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D005820:Genetic Testing; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000235:genetics; D006023:Glycoproteins / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000235:genetics; D010375:Pedigree; D010781:Photography; D017354:Point Mutation; D000099179:Myocilin
D003598:Cytoskeletal Proteins; D005136:Eye Proteins; D006023:Glycoproteins; D000099179:Myocilin