Regional Relationship between Macular Retinal Thickness and Corresponding Central Visual Field Sensitivity in Glaucoma Patients

Elucidating macular structure-function correlations in glaucoma

Correlation between structural data from optical coherence tomography and functional data from the visual field may be suboptimal because of poor mapping of OCT measurement locations to VF stimuli. We tested the hypothesis that stronger structure–function correlations in the macula can be achieved with fundus-tracking perimetery, by precisely mapping OCT measurements to VF sensitivity at the same location. The conventional 64 superpixel (3° × 3°) OCT grid was mapped to VF sensitivities averaged in 40 corresponding VF units with standard automated perimetry (conventional mapped approach, CMA) in 38 glaucoma patients and 10 healthy subjects. Similarly, a 144 superpixel (2° × 2°) OCT grid was mapped to each of the 68 locations with fundus-tracking perimetry (localized mapped approach, LMA). For each approach, the correlation between sensitivity at each VF unit and OCT superpixel was computed. Vector maps showing the maximum correlation between each VF unit and OCT pixel was generated. CMA yielded significantly higher structure–function correlations compared to LMA. Only 20% of the vectors with CMA and < 5% with LMA were within corresponding mapped OCT superpixels, while most were directed towards loci with structural damage. Measurement variability and patterns of structural damage more likely impact correlations compared to precise mapping of VF stimuli.

Macular ganglion cell complex thinning in children with visual field defects due to central nervous system pathology

Purpose

To study the relationship between macular ganglion cell complex (GCC) thickness and visual field defects (VFD) caused by central nervous system (CNS) lesions in children and evaluate the possibility of predicting VFD according to GCC maps.

Methods

The GCC maps of a group of children with VFD due to CNS lesions with respect of the vertical meridian in at least one eye (study group), as well as of children with other neuro-ophthalmological problems and healthy children were presented to two masked evaluators, who were asked to predict the patients’ VFD on the basis of GCC damage: the evaluators classified VFD as normal, hemianopia (homonymous or heteronymous) or diffuse.

Results

Seventeen patients were included in the study group, with a median age of 12 years. Fifteen had brain tumours and two epilepsy. The mean MD of the affected hemifields was −26.00 dB (SD 7.89 dB) versus −5.51 dB (SD 3.52 dB) for the nonaffected hemifields, p < 0.001. The mean GCC thickness was of 56.04 μm (SD 11.95 μm) in the affected hemiretinas versus 74.31 μm (SD 10.64 μm) for the non-affected, p < 0.001. Kappa coefficients between VFD and those estimated by the evaluators were 0.705 and 0.658 (p < 0.001) for evaluators 1 and 2.

Conclusions

GCC thickness can reflect damage to the visual pathway and GCC maps may be useful to identify chiasmal and retrochiasmal lesions, since GCC atrophy in most of these cases respects the vertical meridian. GCC maps might be used as a surrogate marker for visual damage in patients unable to perform perimetry.