Purpose: Previous investigations have demonstrated a relative vascular autoregulatory inefficiency of the inferior compared to the superior retina in healthy subjects breathing increased CO(2). The purpose of this study was to determine whether the superior and inferior visual field sensitivities of healthy eyes are similarly affected during mild hypercapnia.
Design: Experimental study.
Methods: Visual field analysis (Humphrey Field Analyser; SITA standard 24-2 program) was carried out on one randomly selected eye of 22 subjects (mean age, 27.7 +/- 5 years) during normal room air breathing and isoxic hypercapnia. The Student paired t-tests were used to compare the visual field indices mean deviation (MD) and pattern standard deviation (PSD) for each breathing condition. A secondary, sectoral analysis of mean pointwise sensitivity was performed for each condition. In each case a P value of <.01 was considered statistically significant (Bonferroni corrected).
Results: Visual field MD was -0.23 +/- 0.95dB during room air breathing and -0.49 +/- 1.04dB during hypercapnia (P =.034). Sectoral pointwise mean sensitivity deteriorated by 0.46dB (P =.006) in the upper visual hemifield during hypercapnia, whereas no significant difference was observed for the lower hemifield (P =.331).
Conclusions: The upper visual hemifield exhibited a significantly greater degree of deterioration in pointwise visual field mean sensitivity compared to the lower hemifield during hypercapnic conditions. This suggests that the upper visual hemifield and hence inferior retina is more susceptible to insult during hypercapnia than the superior retina in healthy individuals. A regional susceptibility of inferior retinal function to altered vascular or metabolic effects may account for the earlier and more frequent inferior nerve fibre damage associated with glaucomatous optic neuropathy.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/s0002-9394(03)00188-0 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Design Characteristics of Augmentative and Alternative Communication Interfaces for Children With Cortical Visual Impairment: Results From Two Focus Groups With Vision Professionals.
Am J Speech Lang Pathol
January 2025
Department of Speech Pathology, Nationwide Children's Hospital, Columbus, OH.
Purpose: The purpose of the current study was to gain insight on augmentative and alternative communication (AAC) interface designs for children with cortical visual impairment (CVI). Children with CVI frequently require AAC and specific interface supports, and customization may be necessary to support access and use of speech-generating devices.
Method: A focus group methodology was selected to gain feedback from vision professionals on helpful AAC features for children with CVI.
Intermediate-Term Outcomes and Complications of Ahmed Glaucoma Valve in Type 1 Keratoprostheses.
Cornea
January 2025
VST Centre for Glaucoma Care, L V Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad, India.
Purpose: To evaluate intermediate-term outcomes and complications associated with Ahmed glaucoma valve (AGV) implantation in eyes with type 1 keratoprosthesis (KPro).
Methods: We retrospectively reviewed records of 43 eyes of 43 Indian patients with type 1 KPro and AGV from 2009 to 2021 with a minimum of 6-months of follow-up. Five eyes that had AGV before KPro were excluded, leaving 38 eyes for analysis.
Orientation selectivity properties for the affine Gaussian derivative and the affine Gabor models for visual receptive fields.
J Comput Neurosci
January 2025
Computational Brain Science Lab, Division of Computational Science and Technology, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden.
This paper presents an in-depth theoretical analysis of the orientation selectivity properties of simple cells and complex cells, that can be well modelled by the generalized Gaussian derivative model for visual receptive fields, with the purely spatial component of the receptive fields determined by oriented affine Gaussian derivatives for different orders of spatial differentiation. A detailed mathematical analysis is presented for the three different cases of either: (i) purely spatial receptive fields, (ii) space-time separable spatio-temporal receptive fields and (iii) velocity-adapted spatio-temporal receptive fields. Closed-form theoretical expressions for the orientation selectivity curves for idealized models of simple and complex cells are derived for all these main cases, and it is shown that the orientation selectivity of the receptive fields becomes more narrow, as a scale parameter ratio , defined as the ratio between the scale parameters in the directions perpendicular to vs.
View Article and Find Full Text PDFOculomotor challenges in macular degeneration impact motion extrapolation.
J Vis
January 2025
Smith Kettlewell Eye Research Institute, San Francisco, CA, USA.
Macular degeneration (MD), which affects the central visual field including the fovea, has a profound impact on acuity and oculomotor control. We used a motion extrapolation task to investigate the contribution of various factors that potentially impact motion estimation, including the transient disappearance of the target into the scotoma, increased position uncertainty associated with eccentric target positions, and increased oculomotor noise due to the use of a non-foveal locus for fixation and for eye movements. Observers performed a perceptual baseball task where they judged whether the target would intersect or miss a rectangular region (the plate).
View Article and Find Full Text PDFReading comics: The effect of expertise on eye movements.
J Eye Mov Res
November 2024
School of Literature and Journalism Sichuan University, China.
The theory of expertise suggests that there should be observable differences in the eye movement patterns between experts and non-experts. Previous studies have investigated how expertise influences eye movement patterns during cognitive tasks like reading. However, the impact of expertise on eye movements in comics, a multimodal form of text, remains unexplored.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!