Ophthalmic and Physiological Optics最新文献

Purpose: To quantify objectively the influence of brightness artefacts inherent in Scheimpflug tomography on corneal densitometry (CD) estimates.

Methods: Fifty-seven healthy participants aged 30.9 ± 13.7 years (range 17-60 years) were examined with a Ziemer Galilei G2 Scheimpflug tomographer. Images were automatically segmented to isolate the cornea, iris, crystalline lens and corneoscleral lateral brightness regions. CD was calculated as the corneal mean pixel intensity (MPI). Statistical analysis explored the relationship between brightness artefacts and CD across different corneal layers, while also considering age and biometric parameters such as anterior chamber depth and pupil size.

Results: Brightness artefacts accounted for 6.56 ± 1.93% of the pixels in the images, with lateral brightness being the largest source of noise (4.19 ± 0.97%). A strong positive correlation was found between CD and overall brightness artefacts (r = 0.57, p < 0.001). Age was also significantly correlated with both CD (r = 0.65, p < 0.001) and brightness (r = 0.29, p = 0.01). Mediation analysis revealed that age accounts for 60.0% of CD variability, while brightness artefacts contributed 40.0%. Brightness artefacts had the strongest effect on the corneal periphery beyond 7.5 mm as well as the stromal layer.

Conclusion: Brightness artefacts significantly influence CD estimates, particularly in the peripheral cornea. Accurate quantification of these artefacts is essential for proper clinical assessment of corneal transparency, especially in older populations. Future research should focus on identifying the specific sources of artefacts to refine CD measurement techniques.

Purpose: To evaluate the repeatability and agreement of established and newer methods for measuring the amplitude of accommodation in non-presbyopic and early presbyopic individuals.

Methods: The amplitude of accommodation of 81 participants was measured using five different methods (two push-up techniques, two minus lens techniques and one objective technique) with different measurement principles. Among these, two new techniques were introduced: an electronic push-up and a minus lens technique with a tunable lens. Three repeated measurements were performed with each method. The repeatability limit and non-parametric Bland-Altman analysis were used to describe the repeatability and agreement of each method.

Results: The repeatability limit was between ±0.7 D and ±1.4 D for the minus lens techniques, around ±1.8 D for the push-up methods and ±1.4 D for the objective procedure. The largest differences in median values were found between the push-up and objective methods.

Conclusions: Push-up methods are most likely to overestimate accommodation, while the objective method gives the lowest results. New techniques show good repeatability for measuring the amplitude of accommodation. Among the subjective methods, the minus lens technique with the tunable lens gives the best repeatability, is one of the fastest and gives results most similar to the objective method.

The ageing process of adults with a disability may differ from the typical ageing process, yet few studies have addressed ageing of adults who are blind. However, a broad scope of literature exists on ageing with a visual impairment that includes adults who are blind. People who are blind may age differently than people with a visual impairment. Furthermore, it cannot be inferred from studies on the ageing of visually impaired adults that changes are due to the ageing process alone, since vision may decline further as well. This article presents a scoping review of studies on the ageing of adults who are blind, examining the areas of decline due to ageing, differences compared to non-blind adults, additional contributing factors and support. A systematic literature search was performed from inception up to July-October 2023 in Scopus, Medline, Embase, CINAHL, APA PsycInfo and Web of Science. Thirteen articles met the eligibility criteria. Analysis led to four broad areas: physical, sensory, cognitive and psychological. In several of these areas, the decline due to ageing was similar for people who were blind or non-blind. Declines specific to people who were blind were in spatial memory and engagement to the outer world. Two abilities were identified where blind people outperformed sighted people: attention and working memory and active tactile acuity. Overall, ageing blind adults were shown to have additional risks and hence need extra support. Interventions may focus on physical and cognitive exercise, braille training, risk screening, education and social activities. More research is needed to replicate studies and disambiguate results, to include areas that have not been investigated specifically for this group, to differentiate between different types of blindness and to investigate systematically the needs and support of blind adults who are ageing.

Purpose: To assess the ability of the Dolphin air-pulse aesthesiometer to present multiple stimuli, which are separated temporally (in sequence) or spatially (simultaneously).

Methods: Two studies were performed to explore the cooling effects induced by double air-puff stimuli generated by a novel aesthesiometer composed of two micro-blower integrated units. The stimuli were delivered sequentially or simultaneously at the same or different spatial locations to an in vitro eye model monitored using thermography. The model eye was based on a 2-cm LED dome light mounted on a circuit board with an 8-V supply producing a baseline 32°C temperature. Single and repeated air-pulse stimuli varying in intensity, duration, inter-stimulus delay and stimulus location were presented to the model. The cooling effect produced was observed using a thermal camera and quantified using image analysis software.

Results: The instrument can deliver single stimuli, repeated single stimuli with a variable time delay or multiple stimuli either simultaneously or with a time delay between them. The thermal effects of stimuli were evaluated by measuring (relative to pre-stimulus baseline) the local temperature change and the diameter of the model eye surface region with ≥1°C reduction. Repeated stimuli at the same location produced a significantly greater effect than a single stimulus of the same intensity (larger area of cooling after the second stimulus compared to the first [|M|{SE} = 1.48 mm {0.06}, p < 0.001]). Spatially separated stimuli produced separate cooling zones, with the amount of cooling relative to stimulus intensity (rm-ANOVA, F_2,8 = 276.01, p < 0.001, $\omega$ ² = 0.96).

Conclusions: The combined use of two micro-blower units allows increased options for modification of stimulus intensity and timing of delivery that enables the production of alternative stimulus presentations and intensity compared to a single stimulus. This adaptability may enable future in vivo study of corneal sensory nerve summation.

Purpose: This case-control study investigated whether defects in visual field contrast sensitivity are associated with exposure to occupational levels of pesticides in agricultural workers.

Methods: Twenty-seven individuals exposed to occupational levels of pesticides (exposed group) from 14 agricultural systems and 27 non-exposed individuals (non-exposed group) were measured using standard automated perimetry (30-2 full threshold). Visual sector analysis, targeting regions of the optic nerve head, was performed to examine for potential region-specific sensitivity differences. Participants also underwent comprehensive assessments, including general optometric examinations and demographic surveys. Symptoms and signs of neurotoxicity were assessed using the modified Q16 neurotoxic symptom questionnaire and biological testing for abnormal levels of Substance P in tears (an inflammatory marker associated with chemical exposure) and cholinesterase (which is inhibited by pesticides) in blood samples.

Results: Signs of chemical exposure were found as indicated by significantly higher levels of neurotoxic symptoms, higher concentrations of Substance P and lower levels of cholinesterase in the exposed group. Visual field global indices showed differences in contrast sensitivity between the exposed and non-exposed groups, with the exposed group demonstrating significantly lower means and larger pattern-standard deviations. Notably, visual field sector analysis revealed comparatively lower contrast sensitivity at nasal locations surrounding the optic nerve head in the exposed group.

Conclusion: This study found deficits in visual field contrast sensitivity to be associated with pesticide exposure, and selective loss at nasal locations centred on the optic nerve head may indicate retinal toxicity. These findings suggest the utility of visual field assessment as a potential method to evaluate pesticide-related health implications. The results highlight the need for ongoing monitoring and protective measures for agricultural workers exposed to pesticides to prevent potential visual and neurological damage.

Introduction: To evaluate the long-term effect of corneal transplantation on mental health outcomes and to assess potential predictors of these outcomes.

Methods: For this multicentre prospective cohort study, patients awaiting corneal transplantation were recruited from 11 (academic) hospitals and eye clinics in the Netherlands. Participants (n = 238) completed the Centre for Epidemiological Studies Depression scale (CES-D), the Hospital Anxiety and Depression Scale-Anxiety subscale (HADS-A) and the Dutch ICF Activity Inventory Emotional Health subscale (DAI-EH) and Fatigue subscale (DAI-F) 1 month prior and 3, 6, 12 and 24 months after corneal transplantation. Sociodemographic and clinical characteristics, as well as coping styles as measured with the Utrecht Coping List, were considered as potential predictors for mental health outcomes (depression, anxiety, emotional health problems and fatigue). Linear mixed models were used to analyse and predict symptoms of depression, anxiety, emotional health problems and fatigue over time.

Results: Scores on the CES-D and HADS-A improved significantly from baseline to 24-months (mean scores CES-D: 8.6 vs. 7.7, p = 0.03; mean scores HADS-A: 3.7 vs. 3.2, p = 0.002). Scores on the DAI-EH and DAI-F also improved significantly from baseline to 24-months (mean scores DAI-EH: 10.7 vs. 7.5, p < 0.001; mean scores DAI-F: 17.4 vs. 11.3, p < 0.001). Male sex and Fuchs' dystrophy were important predictors of better mental health outcomes, whereas comorbidity, (dry) eye complaints and a passive reacting coping style were important predictors of worse mental health outcomes.

Conclusion: Corneal transplantation had a positive impact on mental health outcomes and important predictors were identified. This study may improve the understanding of patients and eyecare practitioners about the effects of corneal transplantation, leading to realistic communication about corneal transplantation expectations.

Purpose: The present study aimed to determine the potential impact of scleral lenses on intraocular pressure (IOP) by analysing the Bruch's membrane opening-minimum rim width (BMO-MRW) while the lenses are worn, in a population with keratoconus.

Methods: Participants were required to have keratoconus and be successfully fitted with scleral lenses for at least 3 months. A new pair of optimised scleral lenses was provided before the study. During the first session, corneal biomechanics was assessed using an air tonometer, coupling Scheimpflug technology. Then, a scan of the optic nerve was carried out using optical coherence tomography (OCT) at 2 h intervals for 6 h. Particular attention was paid to identifying the BMO-MRW, which represents the smallest distance between the BMO and the internal limiting membrane. These tests were repeated, respecting the time at which the initial measurements were taken, while the scleral lens was worn. Results from only one eye were analysed.

Results: A statistically significant change of 10.5 ± 3.6 μm (95% CI [241.3-473.1]; p = 0.02) in BMO-MRW was observed after 6 h of scleral lens wear, compared to measurements without lenses (4.8 ± 3.4 μm; 95% CI [285.1-439.7]; p = 0.18). The fluctuation was greater in participants with keratoconus than found in a previous study of regular corneas.

Conclusion: BMO-MRW became significantly thinner after 6 h of scleral lens wear compared with measurements without lenses. These variations may be associated with a rise in IOP during lens wear. Close monitoring for optic head changes should be carried out for patients at risk. These results should be compared with future longer-term studies including a larger cohort of patients.