Reduced recovery of temporal contrast sensitivity after flicker stress in patients with glaucoma

Temporal contrast adaptation in the analysis of visual function in primary open-angle glaucoma

PURPOSE

To explore the utility of the recovery time (RT) after temporal contrast adaptation in primary open-angle glaucoma (POAG) visual function analysis, especially in severe and end-stage glaucoma, by the Erlanger Flicker Test (EFT).

METHODS

This study included 80 POAG eyes (45 subjects) and 20 normal eyes (20 subjects). POAG eyes were divided into 5 groups. The diagnostic efficacy of the EFT was assessed, and the RT of POAG eyes at different stages was compared. The EFT results were compared with glaucomatous structure and function test results. A nomogram was developed to predict disease progression by the RT and structural indicators.

RESULTS

In the normal eyes, as the test contrast increased, the RT gradually decreased. The EFT test-retest reproducibility was good, with intraclass correlation coefficient values of 0.6 (P < 0.05) for each test contrast. At 12%, 25%, and 35% contrast, the RT in the severe and end-stage glaucoma eyes was significantly prolonged compared with the control group (P < 0.05). The RT at different contrasts was significantly correlated with visual acuity, mean defect, mean sensitivity, and general and individual quadrant optic nerve fiber layer thickness (P ≤ 0.001). The receiver operating curve indicated that RT_12% showed the best overall area under the curve (0.863). We included RT_25% and average optic nerve fiber layer thickness in constructing the nomogram. POAG eyes were further divided into 8 stages. According to the probability distribution, this model showed good performance for visual function analysis in advanced glaucoma.

CONCLUSIONS

Combined with traditional glaucomatous structural and functional parameters, the EFT can be used in the diagnosis and visual function analysis of POAG, especially for severe and end-stage glaucoma. It could be a potential test for disease staging in severe and end-stage glaucoma.

Dark Adaptation Survey as a Predictive Tool for Primary Open-Angle Glaucoma

PURPOSE

To study the extent to which patients with primary open-angle glaucoma (POAG) have subjective difficulties with dark (DA) adaptation and vision under low-luminance conditions and to correlate the reported difficulties with severity of disease, specifically visual field loss.

DESIGN

Prospective, comparative case series.

PARTICIPANTS

Two hundred twenty patients with and without POAG who sought treatment at an outpatient subspecialty glaucoma clinic between October 2016 and September 2018.

METHODS

A questionnaire designed to assess difficulties with DA and vision under low luminance (the DA survey) was developed and given to patients during routine clinical evaluation in a hospital-based eye clinic. Retrospective data related to ocular health and glaucoma severity were abstracted from the medical record. A multiple regression analysis was performed to create a predictive model for POAG.

MAIN OUTCOME MEASURES

Severity of glaucoma, specifically visual field loss, and classification of participants as glaucoma patients or control participants.

RESULTS

Eighty-five patients with POAG and 127 control participants completed the questionnaire. Exploratory factor analysis of the DA survey using a principal components analysis showed that the items split into 2 dimensions: tasks that involved difficulty with vision under low luminance and those that required DA. Cronbach's α showed a high degree of internal consistency reliability (α = 0.88). Increasing DA survey score correlated with binocular visual field loss among patients with mild, moderate, and advanced POAG (P < 0.001). A model used to differentiate patients with POAG from control participants that included average and intereye difference in cup-to-disc ratio, family history of glaucoma, and DA survey score showed an accuracy, sensitivity, and specificity of 96.7%, 92.9%, and 99.2%, respectively.

CONCLUSIONS

This pilot study revealed that problems with DA and vision under low luminance are commonly encountered by patients with POAG. These areas of visual disability are not assessed routinely in glaucoma care. A questionnaire assessing vision under low luminance and light-dark transitions may serve as a proxy for functional impairment in glaucoma. When paired with risk factors such as structural features of the optic nerve and family history, this survey instrument may be suitable to screen for patients with POAG.

[Recovery time as a potential new progression parameter for patients with advanced glaucomatous optic atrophy]

BACKGROUND

Functional tests in glaucoma diagnosis can monitor a potential perimetric progression. However white-on-white perimetry is limited in advanced glaucoma, whereas contrasts were detected reproducibly. Especially when stressing (i. e. adapting) the visual system, subsequent measurements yielded different results-the visual system needs a "recovery time". In the present study the recovery time was investigated in patients with advanced glaucoma. Additionally correlation analysis was done with standard perimetric parameters.

MATERIAL AND METHODS

Temporal contrast sensitivity (TCS) and recovery time (RT) were measured using the Erlanger Flicker Test in 61 probands (15 normals, 25 primary open-angle glaucomas, 17 secondary open-angle glaucomas, 4 narrow-angle glaucoma). Additionally, ophthalmological examinations and perimetry (Octopus G1) was done.

RESULTS

(1) TCS was significantly reduced in patients with advanced glaucoma (p < 0.001). (2) Test stimuli with 3 and 5 % contrast showed a large variability in contrast to higher contrasts (12 %, 25 %, 35 %). (3) RT_12%, RT_25% and RT_35% were significantly prolonged in advanced glaucoma (p < 0.001). (4) RT_25% correlated significantly with mean defect (p = 0.015).

CONCLUSION

Recovery time seems to be a potential parameter in advanced glaucoma follow-up, as it is reproducible, independently of cataract and fixation.

Long-term evaluation of Leber's hereditary optic neuropathy-like symptoms in rotenone administered rats

Leber's hereditary optic neuropathy (LHON) is an inherited disorder affecting the retinal ganglion cells (RGCs) and their axons that lead to the loss of central vision. This study is aimed at evaluating the LHON symptoms in rats administered with rotenone microspheres into the superior colliculus (SC). Optical coherence tomography (OCT) analysis showed substantial loss of retinal nerve fiber layer (RNFL) thickness in rotenone injected rats. Optokinetic testing in rotenone treated rats showed decrease in head-tracking response. Electrophysiological mapping of the SC surface demonstrated attenuation of visually evoked responses; however, no changes were observed in the ERG data. The progressive pattern of disease manifestation in rotenone administered rats demonstrated several similarities with human disease symptoms. These rats with LHON-like symptoms can serve as a model for future investigators to design and implement reliable tests to assess the beneficial effects of therapeutic interventions for LHON disease.

Flimmerprovokation im LED-Ganzfeld bei Gesunden und Glaukompatienten

BACKGROUND

Flicker light is an easy method to test sensory function after stress. The aim of this study was to determine the influence of flicker stress on temporal contrast sensitivity in healthy controls and patients with glaucomatous alteration of the optic disk.

METHODS

A commercially available full-field stimulator (Retiport, Roland Consult) equipped with white LEDs was modified to perform psychophysical tests. The patients underwent measurements of the recovery time interval from cessation of flicker stress until recognition of a pregiven flicker contrast after photo stress. In addition, we studied contrast sensitivity with a continuous flickering target and with a flicker burst protocol avoiding adaptation to prevailing flicker. All tests were performed at a constant retinal illumination and at a frequency of 37 Hz for provocation as well as for contrast sensitivity tests.

SUBJECTS

Normal healthy controls (40), "preperimetric" (62), and "perimetric" (52) open-angle glaucoma patients were studied. Exclusion criteria were age lower than 31 years, visual acuity under 0.6, and perimetric mean defect more than 9.5 dB.

RESULTS

Recovery time after flicker stress was significantly longer in patients than in normals and longer in perimetric than in preperimetric patients. Analysis in perimetric patients revealed a larger area under ROC for the provocation test (0.95) than in contrast sensitivity tests (continuous flicker method: 0.90, flicker burst mode: 0.84).

CONCLUSION

High-power LEDs which are installed in modern full-field devices can be used as a helpful tool to study psychophysical properties. In the present study it could be shown that threshold, adaptation, and recovery of temporal transfer characteristics are impaired in many patients with glaucoma.

Beyond visual acuity: new and complementary tests of visual function

Visual acuity is an essential component of the routine ophthalmic examination and the most common measure of visual function. There is increasing recognition, however, of the need to evaluate visual function beyond the limited extent afforded by visual acuity. The primary objective of this article is to introduce a variety of new and lesser-used techniques for measuring visual function that complement visual acuity assessment, each of which has been shown to detect visual dysfunction in patients with normal visual acuity.