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

BACKGROUND/AIMS: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: SD-OCT was easier to obtain than TD-OCT in children. SD-OCT and TD-OCT measurements correlated, but values were not interchangeable.

Longitudinal reproducibility of optical coherence tomography measurements in children.

PURPOSE: To evaluate the longitudinal reproducibility of optical coherence tomography (OCT) measurements in normal and glaucomatous eyes of children. METHODS: In this 2-setting prospective study, OCT-3 was used to obtain fast retinal nerve fiber layer (RNFL) and macular thickness scans. In the first study setting, the normal eyes of healthy children were scanned on presentation, at 2 weeks, and 3 years, with axial length measured at the first and last examinations. In the second setting, OCT scans of patients in the pediatric glaucoma clinic were performed over 4 years as clinically indicated. Eyes were classified as "normal" (normal eyes and those with physiologic cupping but normal intraocular pressure [IOP]); "mild glaucoma" (increased IOP and a normal optic nerve appearance); or "advanced glaucoma" (severe cupping or progressive glaucoma). Intraclass correlation coefficients were used to evaluate the reproducibility of measurements on the same day and over time. RESULTS: In the first setting, 8 normal eyes were included. Axial length increased 0.11 ± 0.04 mm/year over an average of 3.3 years (P = 0.03); there was no statistically significant change in RNFL thickness (P = 0.30). In our second setting, 27 normal eyes and 37 eyes with glaucoma were included. Intraclass correlation coefficients across the 3 visits for total macular volume were 0.80-0.91 and for average RNFL were 0.73-0.95. CONCLUSIONS: Global OCT measurements in children were reproducible over years and were not affected by normal increase in axial length. OCT shows promise as an objective tool for longitudinal assessment of children.