Steady-State Pattern Electroretinography in Eyes with Glaucoma and High Myopia

Handheld chromatic pupillometry can reliably detect functional glaucomatous damage in eyes with high myopia

BACKGROUND/AIMS

To assess pupillary light responses (PLRs) in eyes with high myopia (HM) and evaluate the ability of handheld chromatic pupillometry (HCP) to identify glaucomatous functional loss in eyes with HM.

METHODS

This prospective, cross-sectional study included 28 emmetropes (EM), 24 high myopes without glaucoma (HM) and 17 high myopes with confirmed glaucoma (HMG), recruited at the Singapore National Eye Center. Monocular PLRs were evaluated using a custom-built handheld pupillometer that recorded changes in horizontal pupil radius in response to 9 s of exponentially increasing blue (469.1 nm) and red (640.1 nm) lights. Fifteen pupillometric features were compared between groups. A logistic regression model (LRM) was used to distinguish HMG eyes from non-glaucomatous eyes (EM and HM).

RESULTS

All pupillometric features were similar between EM and HM groups. Phasic constriction to blue (p<0.001) and red (p=0.006) lights, and maximum constriction to blue light (p<0.001) were reduced in HMG compared with EM and HM. Pupillometric features of melanopsin function (postillumination pupillary response, PIPR area under the curve (AUC) 0-12 s (p<0.001) and PIPR 6 s (p=0.01) to blue light) were reduced in HMG. Using only three pupillometric features, the LRM could classify glaucomatous from non-glaucomatous eyes with an AUC of 0.89 (95% CI 0.77 to 1.00), sensitivity 94.1% (95% CI 82.4% to 100.0%) and specificity 78.8% (95% CI 67.3% to 90.4%).

CONCLUSION

PLRs to ramping-up light stimuli are unaltered in highly myopic eyes without other diagnosed ocular conditions. Conversely, HCP can distinguish glaucomatous functional loss in eyes with HM and can be a useful tool to detect/confirm the presence of glaucoma in patients with HM.

[The association between myopia and glaucoma]

Myopia and glaucoma are the leading causes of irreversible blindness in the world, and as the number of nearsighted people is predicted to increase sharply in the upcoming decades, an increase in combined pathology is expected. This article analyzes literature sources to assess the epidemiology of glaucoma and myopia both worldwide and in the Russian Federation, examine the anatomical changes of the eyeball associated with these diseases, and identify the diagnostic criteria that facilitate the verification of glaucoma when combined with myopia.

Posterior Pole Asymmetry Analysis as a Diagnostic Tool in Glaucoma Suspects: An Electrophysiological Approach

Purpose

Spectral domain optical coherence tomography (SD-OCT) with posterior pole asymmetry analysis (PPAA) provides a mapping of posterior pole retinal thickness with asymmetry analysis between hemispheres of each eye. We investigated whether these structural abnormalities were correlated with functional retinal ganglion cell (RGC) loss, quantified by steady state pattern electroretinogram (ssPERG), in glaucoma suspects (GS).

Methods

Twenty GS (34 eyes) were enrolled in a prospective study at the Manhattan Eye, Ear, and Throat Hospital. All subjects underwent ophthalmological examination, including Humphrey visual field, Spectralis Glaucoma Module Premium Edition (GMPE) SD-OCT PPAA, and ssPERG testing. The ability of ssPERG parameters (Magnitude [Mag, µv], MagnitudeD [MagD, µv], and MagD/Mag ratio) to predict PPAA thickness (total, superior, and inferior thickness, [µm]) was tested via adjusted multivariate linear regression analysis.

Results

Mag explained 8% of variance in total PPAA change (F(1,29)=6.33, B=6.86, 95% CI: 1.29-12.44, p=0.018), 8% in superior PPAA change (F(1,29)=5.57, B=6.92, 95% CI: 0.92-12.92, p=0.025), and 7.1% in inferior PPAA change (F(1,29)=5.83, B=6.80, 95% CI: 1.04-12.56, p=0.022). Similarly, MagD explained 9.7% of variance in total PPAA change (F(1,29)=8.09, B=6.47, 95% CI: 1.82-11.13, p=0.008), 10% in superior PPAA change (F(1,29)=7.33, B=6.63, 95% CI: 1.62-11.63, p=0.011), and 8.5% in inferior PPAA change (F(1,29)=7.25, B=6.36, 95% CI: 1.53-11.18, p=0.012). MagD/Mag ratio and PPAA were not significantly associated.

Conclusion

To the best of our knowledge, this is the first study demonstrating a positive relationship between RGC dysfunction and retinal thickness changes between the superior and inferior hemispheres. The detection of asymmetrical structural loss, combined with functional RGC assessment using ssPERG, may be an informative tool for early glaucoma diagnosis.