Disagreement between Heidelberg Retina Tomograph and optical coherence tomography in assessing optic nerve head configuration of eyes with band atrophy and normal eyes.

BACKGROUND/AIMS: To evaluate to what extent the optic nerve head (ONH) parameters as measured with Heidelberg Retina Tomograph (HRT) differed from those measured with optical coherence tomography (OCT) in eyes with compressive optic neuropathy (CON) that had band atrophy (BA) of the optic disc. METHODS: A total of 30 eyes from 19 patients with BA due to chiasmal tumour and 162 eyes from 162 normal subjects were examined with HRT and Stratus OCT using the fast optic nerve scan protocol. Parameters measured by the two devices, including the disc area, cup/disc (C/D) area ratio, cup area, cup volume, rim area and rim volume, were compared between the eyes of BA patients and controls. Bland-Altman plots were used to evaluate agreement for each parameter between OCT and HRT in both groups of eyes. Intermethod discrepancy of the measurements for each parameter was compared between the two groups of eyes. RESULTS: Eyes with BA had smaller cup and larger rim parameters than control eyes when measured with HRT, whereas they had significantly larger cup and significantly smaller rim parameters than control eyes when measured with OCT. HRT measurements tended to be consistently lower in the C/D area ratio and cup area and higher in the rim area and rim volume than OCT measurements for both control eyes and eyes with BA. The intermethod discrepancy for all the parameters except the disc area was significantly larger in eyes with BA than in control eyes. CONCLUSION: The increased optic disc excavation was detected with OCT but not with HRT in CON eyes with BA of the optic disc. Thus, the distinct algorithms used by these two modalities affected the measurements of ONH parameters, particularly when assessing optic discs with temporal rim thinning.

Association of retinal nerve fibre layer thickness measured by confocal scanning laser ophthalmoscopy and optical coherence tomography with disc size and axial length.

AIMS: To investigate the influence of age, disc size and axial length on the retinal nerve fibre layer (RNFL) thickness measurements of Heidelberg Retina Tomograph (HRT) and optical coherence tomography (OCT). METHODS: A total of 162 eyes of 162 Japanese normal subjects aged between 20 and 83 were enrolled in this study. The disc area and mean RNFL thickness were measured with HRT. The disc area was also measured using the fast optic nerve scan protocol, and the average RNFL thickness was measured using the fast RNFL thickness scan mode with Stratus OCT. The correlations of age, disc area and axial length with RNFL thickness measured with HRT and OCT were analysed. The associations between axial length and disc area measured with HRT and OCT were also calculated. RESULTS: RNFL thickness measured with the two instruments decreased with age. There was a significantly negative correlation between the mean RNFL thickness and disc area measured with HRT. The RNFL thickness measured with OCT correlated positively with the disc area measured with OCT, but not with the disc area measured with HRT. Both RNFL thickness and disc area measured with OCT were inversely correlated with axial length, whereas the two parameters measured with HRT had no association with axial length. CONCLUSION: In addition to the effect of ageing, the disc size affected the RNFL thickness measured with HRT, whereas the axial length influenced the RNFL thickness and disc area measured with OCT. These variables must be taken into consideration when measuring eyes with the lower or upper boundary of the normal range.

Evaluation of optic nerve head configuration in various types of optic neuropathy with Heidelberg Retina Tomograph.

PURPOSE: To test whether Heidelberg Retina Tomograph (HRT) is applicable to assess the optic nerve head (ONH) configuration of the atrophic phase of non-glaucomatous optic neuropathy when a default set of the reference plane is used. METHODS: Ten eyes with non-arteritic anterior ischaemic optic neuropathy (NAION), 17 eyes with Leber's hereditary optic neuropathy (LHON), 40 eyes with compressive optic neuropathy (CON) owing to chiasmal tumour, and 241 eyes of control individuals were examined with HRT using the default reference plane. The global values of HRT parameters were evaluated among the groups of patients and controls. The sectoral measurements of the eyes with LHON and CON were compared with controls. To eliminate the influence of disc size and age on HRT measurements, eyes with disc area- and age-matched normal controls were used for comparison with eyes with NAION and LHON. RESULTS: Cup parameters in eyes with NAION were similar to those in controls. The retinal nerve fibre layer (RNFL) thickness was significantly thinner in eyes with NAION than that of controls. The eyes with LHON had significantly larger cup parameters, smaller rim volume, and thinner mean RNFL thickness than controls. Eyes with CON had significantly larger rim area and smaller cup parameters but similar RNFL thickness compared with controls. CONCLUSIONS: When the default reference plane is used, HRT can measure the ONH configuration in eyes with NAION and LHON as expected. However, caution must be made to interpret the parameters obtained from the eyes with CON.

Macular thickness reduction in eyes with unilateral optic atrophy detected with optical coherence tomography.

AIMS: To assess the changes in macular and peripapillary retinal nerve fibre layer (RNFL) thickness in eyes with unilateral optic atrophy and to evaluate the relationship between retinal thickness and visual function. METHODS: Enrolled were 22 patients with unilateral optic atrophy. Macular thickness at the divided nine areas and peripapillary RNFL thickness in quadrantic sections were measured by optical coherence tomography. Thickness values in the affected eyes were compared with those in the contralateral unaffected eyes. The correlation of foveal thickness with best-corrected visual acuity (BCVA) was evaluated. The correlation between retinal thickness and the remaining visual field area circumscribed with I-4-e isopter in superior and inferior hemifield was assessed. RESULTS: Macular thinning was observed in all areas (P < 0.001 in each area) other than the fovea (P = 0.068). Peripapillary RNFL thickness decreased in all quadrantic sections (P < 0.001 in each section). The affected to unaffected eye ratio of retinal thickness was more than 0.6 in each area. BCVA did not correlate with foveal thickness (correlation coefficient = 0.094, P = 0.668). Although not statistically significant (P = 0.281, superior hemifield; P = 0.053, inferior hemifield), there was a tendency that eyes with severe visual field loss show more marked retinal thinning. CONCLUSIONS: Macular thinning with the preserved foveal thickness is a hallmark of eyes with optic atrophy. Together with no correlation between foveal thickness and BCVA, this finding would help in differential diagnosis of macular and optic nerve diseases.