Optical coherence tomography in paediatric glaucoma: time domain versus spectral domain

Spectral-domain (SD)- Optical Coherence Tomography (OCT) can track eye movements, has faster acquisition time and higher resolution than time-domain(TD)-OCT. The aim of the study was to assess the utility of SD-OCT in paediatric glaucoma and determine its agreement with TD-OCT.

Children who had SD-OCT(Spectralis, Heidelberg-Engineering,Germany) were retrospectively and prospectively identified from Duke paediatric glaucoma clinic. The peripapillary retinal nerve fibre layer (RNFL) and macular thickness and volume (MV) were compared amongst four groups: normal eyes, eyes with physiologic cupping (C:D >0.5 and <0.8, IOP <21), mild glaucomatous eyes (C:D <0.5, intra-ocular pressure (IOP) >21) and severe glaucoma (C:D>0.5, IOP>21). SD-OCT values were compared to TD-OCT(OCT-3, Carl-Zeiss-Meditec, Dublin, CA) values in a subset of subjects who had same day scans using both instruments. Children with neurologic disorders, refractive error >±5D, pseudophakia and prematurity were excluded.

Included were 83 eyes of 83 children, mean age 11.9 ± 4.2 years. SD-OCT measurements of average RNFL thickness and MV differed among normals(n=24), physiologically cupped (n=31), mild (n=15) versus severe glaucoma (n=13): (RNFL:104 ± 9, 99 ± 6, 98 ± 9 vs 62 ± 18 µm, respectively, p<0.05; MV: 8.7 ± 0.3, 8.6 ± 0.3, 8.8 ± 0.4 vs 8.0 ± 0.6 mm³;, respectively, p<0.05). Same-day SD-OCT and TD-OCT measures in 53 eyes correlated linearly (RNFL r(2)=0.88; MVr(2)=0.58). SD-OCT measured lower RNFL and higher macular thickness than TD-OCT. Among eyes with severe glaucoma, 4 of 13 (30%) had unreliable TD-OCT but reliable SD-OCT.

SD-OCT was easier to obtain than TD-OCT in children. SD-OCT and TD-OCT measurements correlated, but values were not interchangeable.