Heidelberg retinal tomography of optic disc and nerve fiber layer in singapore children: variations with disc tilt and refractive error.
OBJECTIVE
To evaluate the relationships in Singapore school children between optic nerve head parameters and retinal nerve fiber layer thickness images by using the Heidelberg Retinal Tomograph (HRT; Heidelberg Engineering, Heidelberg, Germany) and determining optic disc tilt and refractive error.


METHODS
This was a cross-sectional study involving 316 children 11 and 12 years of age (163 girls and 153 boys) selected randomly from one of the three schools in the Singapore Cohort study of Myopia. A total of 13 optic disc parameters were obtained from HRT images acquired before cycloplegia. Refractive errors were measured by cycloplegic autorefraction. The presence of optic disc tilt or otherwise was determined by two independent assessors using stereoscopic viewing of retinal photographs.


RESULTS
Of the 316 children, 142 had tilted discs. The tilting of optic discs was associated with a smaller disc, rim or cup area measurements, cup-to-disc area ratios, cup volumes or cup depths, but with a larger measured rim volume, rim-to-disc area ratios, height variation of the contour, retinal nerve fiber layer thicknesses or volumes, and a more negative cup shape measure (all P < 0.001). Decreased maximum cup depths were significantly associated with longer axial lengths (P < 0.001), but were not associated with spherical equivalent (P = 0.693). These associations remained only in children without tilted discs, but were no longer significant in those with tilted discs. Other HRT parameters were not associated with axial lengths or myopic status.


CONCLUSIONS
Optic nerve head parameters and retinal nerve fiber layer thickness measured by the current HRT algorithms are strongly influenced by the tilting of the optic nerve head, but not by refractive errors or axial length.
Tong
Louis
L
Singapore National Eye Center, Singapore. louistong@hotmail.com
Chan
Yiong-Huak
YH
Gazzard
Gus
G
Loon
Seng-Chee
SC
Fong
Allan
A
Selvaraj
Prabakaran
P
Healey
Paul R
PR
Tan
Donald
D
Wong
Tien Yin
TY
Saw
Seang Mei
SM
D002648:Child; D003430:Cross-Sectional Studies; D003519:Cyclopentolate / Q000008:administration & dosage; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D008297:Male; D009184:Mydriatics / Q000008:administration & dosage; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000002:abnormalities*; D010781:Photography; D011680:Pupil / Q000187:drug effects; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000150:complications*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012846:Singapore; D014054:Tomography / Q000379:methods
D009184:Mydriatics; D003519:Cyclopentolate