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.