Comparison of frequency doubling and flicker defined form perimetry in early glaucoma

Relationship Between Flicker Modulation Sensitivity and Retinal Ganglion Cell Related Layer Thicknesses

Purpose

Early detection of structural changes in retinal ganglion cells (RGCs) and corresponding changes in visual function is important in early degenerative diseases of the retina, but the sensitivity of both measurements is limited by the inherent variability in healthy subjects. This study investigates the relationships between RGC-related layer thicknesses and foveal and parafoveal flicker modulation sensitivity (FMS) across photopic and mesopic light levels in healthy subjects.

Methods

Photopic and mesopic FMS was measured in 56 young adults, at the point of fixation and at an eccentricity of 5 degrees, in each of the four quadrants. Spectral-domain optical coherence tomography (SD-OCT) was used to measure retinal thicknesses. Relationships between foveal and parafoveal FMS and the retinal thickness in the corresponding region were examined after adjusting for confounding variables.

Results

Total macular and inner retinal layer (IRL) thicknesses in the parafoveal ring were significant predictors of photopic (P = 0.034) and mesopic (P = 0.034) parafoveal FMS, respectively. The superior peripapillary retinal nerve fiber layer (pRNFL) thickness was a contributing factor to the inferior parafoveal FMS (photopic: P = 0.006 and mesopic: P = 0.021) and the inferior pRNFL thickness was also a contributing factor to the superior parafoveal FMS (photopic: P < 0.001 and mesopic: P = 0.015).

Conclusions

The pRNFL thicknesses predict parafoveal FMS for both mesopic and photopic conditions in healthy eyes.

Translational Relevance

The measurement of rapid flicker sensitivity in the parafoveal retina together with the pRNFL thickness profiles measured before the onset of disease, may provide a more sensitive biomarker for detecting loss of sensitivity caused by the earliest neurodegenerative changes in the eyes.

Non-standard computer perimetry in the diagnosis of some optic neuropathies

Modern computer perimetry is divided into traditional white stimulus-on-white background, the gold standard of which is perimetry performed by using expert class perimeters Humphrey and Octopus and therefore called standard automatic or automated perimetry (SAP), and non-traditional or non-standard perimetry, which differs, first of all, in a different nature of a stimulus. The article is a review devoted to the assessment of the diagnostic capabilities of non-standard computer perimetry in the form of different variants of perimetry with doubling the spatial frequency (Frequency Doubling Technology Perimetry or FDT perimetry), which is performed by using perimeters of the 1st (Carl Zeiss Humphrey 710 Visual Field / FDT, 1997) and the 2nd (Carl Zeiss Humphrey Matrix / HM 715, 800 Visual Field Analyzer, 2005, 2010) generation. Most authors consider that FDT perimetry is effective in a glaucoma screening and, possibly, in monitoring a glaucomatous process, but only a few authors consider that non-standard perimetry method can be useful in diagnosing optic neuropathies of a different nature.

Novel Technique for Quantifying Retinal Nerve Fiber Bundle Abnormality in the Temporal Raphe

SIGNIFICANCE

Glaucomatous nasal visual field abnormalities correspond to damage in the temporal raphe-where individual nerve bundles can be visualized. The ability to quantify structural abnormality in the raphe, with a clinically applicable protocol, sets the stage for investigating the raphe as a potential site for assessing early glaucoma.

PURPOSE

To develop a clinically applicable imaging and analysis technique for identifying retinal nerve fiber bundle abnormalities in the temporal raphe.

METHODS

Spectralis optical coherence tomography scans customized for the temporal raphe were gathered from 30 younger controls, 30 older controls, and 29 patients with glaucoma. An analysis technique was developed based on the reflectance of the nerve fiber bundles. The technique was first developed in the younger controls, and then applied to the older controls to generate normative data for quantifying nerve fiber bundle reflectance abnormalities in the patients with glaucoma. Matrix perimetric data were gathered in the patients with glaucoma to evaluate the reflectance technique's findings. Reflectance abnormality in the patients was defined when the fraction of enface area showing reflectance abnormality was greater than the 95th percentile estimated from controls. Spearman's rho was used to quantify the relation between the total deviation at the perimetric testing locations and the fraction of corresponding enface area showing reflectance abnormality.

RESULTS

Twenty-five of the 29 patients had reflectance abnormalities. Eight of these had mild to no perimetric mean deviation abnormality. Similar results were found when perimetric total deviations were compared to reflectance abnormalities in the corresponding enface locations. Spearman's rho comparing the total deviations to reflectance abnormalities found rs(174) = -0.72, P < .001.

CONCLUSIONS

The technique typically identified reflectance abnormality when perimetric abnormality was present. It also identified reflectance abnormalities even when perimetric abnormality was mild or absent. The findings support the potential of raphe imaging in detecting early glaucomatous damage.

Validation and reproducibility of the Heidelberg Edge Perimeter in the detection of glaucomatous visual field defects

AIM

To validate the ability of the Heidelberg Edge Perimeter (HEP) in detecting glaucomatous visual field (VF) defects compared to the Octopus Visual Field (OVF) Analyzer and to determine the test-retest repeatability of both modalities.

METHODS

This prospective, cross-sectional study was conducted at Wills Eye Hospital, Philadelphia, PA. Glaucoma subjects and unaffected controls underwent VF testing using HEP standard automated perimetry (SAP) III 30-2 Adaptive Staircase Thresholding Algorithm (ASTA) FAST protocol and OVF G-TOP white-on-white strategy. Testing order was randomized. Pearson's correlation coefficient was calculated for both mean deviation (MD) and pattern standard deviation/square root of loss of variance (PSD/sLV). Receiver operating characteristic (ROC) curves were used to determine the diagnostic abilities of both modalities. Glaucoma subjects returned for repeat testing and intraclass correlation coefficients (ICCs) were calculated to assess test-retest repeatability.

RESULTS

Seventy-nine subjects with glaucoma and 36 unaffected controls were enrolled. HEP and OVF were significantly correlated for both MD (r=-0.84; P<0.01) and PSD/sLV (r=0.79; P<0.01). Areas under the ROC curves (AUCs) were also comparable between HEP and OVF for both MD (0.74 and 0.79, respectively; P=0.26) and PSD/sLV (0.74 and 0.82; P=0.08). ICC was high for both HEP (0.96 for MD, 0.95 for PSD/sLV) and OVF (0.82 and 0.88, respectively). Mean test duration (min) was significantly shorter for OVF (2.63) compared to HEP (5.15; P<0.01).

CONCLUSION

HEP and OVF show strong correlation for both MD and PSD/sLV, and have similar validity for detecting glaucoma. The test-retest repeatability is high for both HEP and OVF, however the average testing duration of HEP is significantly longer than that of OVF.

Diagnostic Ability and Repeatability of a New Supra-Threshold Glaucoma Screening Program in Standard Automated Perimetry

Purpose

We assess the diagnostic ability and repeatability of a new suprathreshold glaucoma screening test (GST) comprising 28 test points and a 1-of-3 sampling strategy at 95% of the normal limit for standard automated perimetry (SAP) in early to advanced glaucoma.

Methods

This prospective cross-sectional study included 96 eyes of patients with early, moderate, or advanced glaucoma and 37 eyes of normal controls. Participants were evaluated by the G-Dynamic threshold test once and the GST twice, in random order, using the Octopus 600 perimeter. The diagnostic ability of GST was assessed by comparison with the G-Dynamic threshold obtained by receiver operating characteristic analysis. Repeatability was assessed by κ statistics for agreement on glaucoma diagnosis and each test point.

Results

Although the G-Dynamic test exhibited significantly higher areas under the curve (AUC) than the GST_1st (P = 0.009) in early glaucoma, there were no significant differences in any other AUCs between the two methods. The κ values for repeatability of glaucoma diagnosis and each test point were 0.747 to 1.0 and 0.537 to 1.0, respectively. The duration of the GST in the control and early glaucoma groups was less than a minute, while that in the moderate and advanced glaucoma groups was within 1.5 minutes.

Conclusion

The diagnostic ability of the new suprathreshold GST for early to advanced glaucoma was high, with moderate to strong repeatability and short test duration.

Translational Relevance

There currently are no prominent suprathreshold screening strategies using SAP. The GST would be an effective clinical method for glaucoma screening.