Predicting conversion to glaucoma using standard automated perimetry and frequency doubling technology

Pattern electroretinogram, blue-yellow visual evoked potentials and the risk of developing visual field defects in glaucoma suspects: a longitudinal "survival" analysis with a very long follow-up

PURPOSE

Estimating glaucoma suspects' risk for visual field defects helps to avoid under- and over-treatment. In this retrospective, longitudinal cohort study with a very long follow-up, we studied whether pattern electroretinograms (PERG) amplitudes and blue-on-yellow visual evoked potential (BY-VEP) latencies can predict visual field defects.

METHODS

Participants of the Erlangen Glaucoma Study were examined with PERG and BY-VEP between 9/1991 and 8/2001. Stimuli were created using an optical bench with Maxwellian view and consisted of vertical gratings (0,88 cpd) in a 32° field for both PERG and BY-VEP. Patients were treated according to clinical standards and performed standard automated perimetry (SAP) annually. Retrospectively, patients with normal SAP at baseline were selected. Primary endpoint was conversion to perimetric glaucoma. Predictive value was modeled using Kaplan-Meier analyses and a multivariate cox proportional hazards model with the continuous variables PERG amplitude, BY-VEP peak time and SAP square-root of loss variance (sLV) after stratification for Jonas classification of the optic discs.

RESULTS

Of 412 patients (288: Jonas 0, 103: I, and 21: II; baseline age: 20-60 years), 65 converted to perimetric glaucoma during follow-up (0.5-23.3 years; median 5.5 years). Optic disc classification was a strong risk factor for conversion (log rank p < 0.0001), and patients with more advanced changes progressed earlier. In the multivariate analysis (log rank p = 0.005), only PERG amplitude remained an independent risk factor after stratification for optic disc morphology (p = 0.021), with a ~ 30% higher risk per μV amplitude decrease.

CONCLUSIONS

PERG helps to estimate glaucoma suspects' risk for visual field defects.

Comparing isolated-check visual evoked potential, pattern visual evoked potential, and standard automated perimetry in dysthyroid optic neuropathy eyes

Objective

To determine the diagnostic ability of isolated-check visual evoked potential (icVEP), pattern visual evoked potential (pVEP), and standard automated perimetry (SAP) between dysthyroid optic neuropathy (DON) and thyroid-associated ophthalmopathy (TAO) without DON (non-DON).

Methods

This is a case-control study, 49 bilateral patients (26 DON and 23 non-DON) were included. icVEP, pVEP, and SAP were conducted in all the subjects, icVEP parameters compared were signal-to-noise ratios (SNRs) under 8, 16, and 32% depth of modulation (DOM). pVEP parameters compared were amplitude and latency. SAP parameters were mean deviation (MD) and pattern standard deviation (PSD). The area under the receiver operating characteristic (ROC) curve (AUC), net reclassification index (NRI), integrated discrimination index (IDI), and decision curve analysis (DCA) were applied for analysis.

Results

In icVEP, values of SNR in DON were significantly smaller than non-DON (p < 0.05). In pVEP, P100 latent time in DON was significantly larger than non-DON (p = 0.0026). In SAP, value of PSD in DON was larger than non-DON (p = 0.0006), and value of MD in DON was smaller (p = 0.0007). AUC, NRI, and IDI among the three tests were not significantly different. DCA showed that SNR of icVEP under 8% DOM was the farthest from the two extreme curves.

Conclusions

icVEP, pVEP, and SAP have equal diagnostic capabilities to discern between DON and non-DON. In addition, icVEP may represent a significant ancillary diagnostic approach to DON detection, with more clinical benefit.

Functional assessment of glaucoma: Uncovering progression

Clinicians who manage glaucoma patients carefully monitor the visual field to determine if treatments are effective or interventions are needed. Visual field tests may reflect disease progression or variability among examinations. We describe the approaches and perimetric tests used to evaluate glaucomatous visual field progression and factors that are important for identifying progression. These include stimulus size, which area of the visual field to assess (central versus peripheral), and the testing frequency, evaluating which is important to detect change early while minimizing patient testing burden. We also review the different statistical methods developed to identify change. These include trend- and event-based analyses, parametric and nonparametric tests, population-based versus individualized approaches, as well as pointwise and global analyses. We hope this information will prove useful and important to enhance the management of glaucoma patients. Overall, analysis procedures based on series of at least 5 to 6 examinations that require confirmation and persistence of changes, that are guided by the pattern and shape of the glaucomatous visual field deficits, and that are consistent with structural defects provide the best clinical performance.

THE ROLE OF FREQUENCY DOUBLING TECHNOLOGY PERIMETRY IN EARLY DETECTION OF DIABETIC RETINOPATHY

The aim was to assess whether standard automated perimetry (SAP) and frequency doubling technology (FDT) perimetry are able to detect the effect of diabetes mellitus (DM) on retinal function in DM patients in the early stage of disease and to analyze which method is more specific and sensitive. A randomized cross-sectional study was conducted in three different groups of patients to compare the capability of these two methods to examine visual field and to detect the change in light sensitivity. Visual function was assessed in 60 adults with normal retinal finding, 60 adults with DM without clinically detectable retinopathy and 60 adults with DM and non-proliferative diabetic retinopathy but normal visual acuity. FDT perimetry and SAP were performed in all study patients. The presence and severity of diabetic retinopathy was determined by taking and evaluating two 50° field color photographs per eye, macula-centered and disc-centered. The following results were obtained by analyzing parameters in the groups of diabetic patients: sensitivity and specificity of SAP and FDT for medium sensitivity 86.7/33.3 (p<0.061) and 71.7/41.7 (p<0.228), respectively; for medium deficit 41.7/76.7 (p<0.063) and 65/50 (p<0.362), respectively; for loss of variance/pattern standard deviation (LV/PSD) 51.7/61.7 (p<0.536) and 61.7/51.7 (p<0.666), respectively; and for foveal sensitivity 81.7/36.7 (p<0.096) and 23.3/86.7 (p<0.839), respectively. Analysis of parameters between diabetics and control group yielded sensitivity and specificity for medium sensitivity 71.7/61.7 (p<0.001) and 70.8/55 (p<0.002), respectively; for medium deficit 56.7/60 (p<0.058) and 77.5/43.3 (p<0.037), respectively; for LV/PSD 58.3/58.3 (p<0.042) and 33.3/83.3 (p<0.437), respectively; and for foveal sensitivity 82.5/53.3 (p<0.001) and 28.3/85 (p<0.195), respectively. We concluded that neither of these methods was sensitive and specific enough to distinguish diabetics without retinopathy from diabetics with retinopathy. Both of these methods were highly specific and sensitive to distinguish diabetics from healthy subjects, but neither of these methods proved superior.