Posterior pole asymmetry analysis and retinal nerve fibre layer thickness measurements in primary angle-closure suspect patients

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.

Posterior Pole Asymmetry Analysis in the Children with Anisometropia

Objectives

The objectives of the study were to investigate the inter and intraocular differences in posterior pole asymmetry analysis (PPAA) with optical coherence tomography (OCT) in anisometropia, to examine the relationship between the presence of anisometropia and amblyopia and retinal thickness.

Methods

Patients between ages of 5 and 16 years with anisometropia who applied to our clinic were included in the study. Macular retinal thickness measurements were evaluated by PPAA using the posterior pole algorithm of the spectral domain-OCT device. Asymmetry was analyzed both as the difference between the right and left eyes and the difference between the superior, inferior, and mean retinal thicknesses of 64 separate quadrants in the same eye. Hemispheric and right-left eye asymmetry differences analyses were performed.

Results

118 patients were included in the study(65 females and 53 males). Group 1 consisted of anisometropic patients (n=46), Group 2 consisted of anisometropic amblyopia patients (n=40), and Group 3 consisted of control group (n=32). The mean age of the patients was 9.72±5.6 years. The mean spherical equivalent difference between the two eyes of the patients was 1.7±0.6 D. When anisometropic eyes were compared with normal eyes, there was no significant difference between mean superior, inferior and total retinal thickness, and right-left eye asymmetry values (for all, p>0.05). In the asymmetry evaluation performed by counting the black boxes in the PPAA, a significant difference was found in the right-left asymmetry evaluation in anisometropic amblyopic eyes, in some quadrants and in the right-left asymmetry analysis (p<0.05).

Conclusion

While no difference was found between anisometropic and normal eyes in the PPAA, there was differences in some quadrants in the anisometropic amblyopic group compared to the control group suggesting that there is an involvement in the peripheral quadrants of the macula, especially in treatment resistant amblyopic patients.

Measures of disease activity in glaucoma

Glaucoma is the leading cause of irreversible blindness globally which significantly affects the quality of life and has a substantial economic impact. Effective detective methods are necessary to identify glaucoma as early as possible. Regular eye examinations are important for detecting the disease early and preventing deterioration of vision and quality of life. Current methods of measuring disease activity are powerful in describing the functional and structural changes in glaucomatous eyes. However, there is still a need for a novel tool to detect glaucoma earlier and more accurately. Tear fluid biomarker analysis and new imaging technology provide novel surrogate endpoints of glaucoma. Artificial intelligence is a post-diagnostic tool that can analyse ophthalmic test results. A detail review of currently used clinical tests in glaucoma include intraocular pressure test, visual field test and optical coherence tomography are presented. The advanced technologies for glaucoma measurement which can identify specific disease characteristics, as well as the mechanism, performance and future perspectives of these devices are highlighted. Applications of AI in diagnosis and prediction in glaucoma are mentioned. With the development in imaging tools, sensor technologies and artificial intelligence, diagnostic evaluation of glaucoma must assess more variables to facilitate earlier diagnosis and management in the future.

Macular imaging with optical coherence tomography in glaucoma

With the advent of spectral-domain optical coherence tomography, imaging of the posterior segment of the eye can be carried out rapidly at multiple anatomical locations, including the optic nerve head, circumpapillary retinal nerve fiber layer, and macula. There is now ample evidence to support the role of spectral-domain optical coherence tomography imaging of the macula for detection of early glaucoma. Macular spectral-domain optical coherence tomography measurements demonstrate high reproducibility, and evidence on its utility for detection of glaucoma progression is accumulating. We present a comprehensive review of macular spectral-domain optical coherence tomography imaging emerging as an essential diagnostic tool in glaucoma.