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Abstract This prospective study investigated the magnitude and pattern of variation in choroidal optical coherence tomography angiography (OCT-A) indices every 4 h over 24 h in healthy young myopic (n = 24) and non-myopic (n = 20) adults. Choriocapillaris and deep choroid en-face images from macular OCT-A scans were analysed from each session to extract magnification-corrected vascular indices including choriocapillaris flow deficit number, size and density and deep choroid perfusion density in the sub-foveal, sub-parafoveal, and sub-perifoveal regions. Choroidal thickness was also obtained from structural OCT scans. Significant variations over 24 h (P

Purpose: To evaluate the repeatability of retinal and choroidal optical coherence tomography angiography (OCT‐A) indices among healthy children and compare it to healthy young adults. Methods: This prospective study captured 3 mm × 3 mm and 6 mm × 6 mm macular OCT‐A scans including superficial and deep retinal layers, choriocapillaris and deep choroid over two visits, 1 week apart at approximately the same time of day, for 22 healthy adults (18–30 years) and 21 children (6–15 years). Magnification and projection‐artefact corrected indices extracted using a custom image analysis program and individual biometry were compared between visits using Bland–Altman analysis and intraclass correlation (ICC). Retinal indices included foveal avascular zone metrics, perfusion and vessel density and choroidal indices included choriocapillaris flow deficit metrics and deep choroid perfusion density, in the foveal, parafoveal and perifoveal regions. Repeatability between adults and children was compared with F‐test. Results: Bland–Altman analysis showed that the mean differences between repeated OCT‐A indices were not significantly different from zero for either of the zones, layers and scan sizes in the two age groups (p > 0.05) except for foveal vessel density and foveal avascular zone perimeter (p = 0.04 for both) of 6‐mm‐deep retinal layer scans. The ICC ranged between 0.67 and 0.99. Significantly higher variability between visits (p < 0.05) in the indices was noted among adults than children, especially for choroidal indices of larger scan size. Conclusion: The retinal and choroidal OCT‐A indices in the foveal, parafoveal and perifoveal zones were repeatable in healthy children except for the foveal vessel density and foveal avascular zone perimeter of the 6‐mm‐deep retinal layer, which exhibited statistically borderline differences between visits. The adult group showed more variability between visits compared to children, especially in the larger scan size for choroidal OCT‐A indices. [ABSTRACT FROM AUTHOR]

Optical coherence tomography angiography (OCT-A) indices are likely to change across time and optometrists should be aware of the variability expected during childhood development and in healthy adults. Cross-sectional studies have shown that OCT-A indices are associated with age in adults and children. The aim of this study is to investigate longitudinal changes in retinal and choroidal OCT-A indices over 1 year among healthy children and young adults. This prospective longitudinal study captured macular OCT-A and OCT scans, and biometry measures at baseline and 1-year follow-up for 22 adults (18–30 years; −6.87 to +0.37 D) and 21 children (6–15 years; −5.75 to +0.25 D). Superficial and deep retinal layer, choriocapillaris and deep choroidal en face OCT-A images were analysed to extract magnification-corrected vascular indices in foveal, parafoveal and perifoveal regions. The retinal indices included foveal avascular zone metrics, perfusion, and vessel density. Flow deficit number, size, and density were extracted from choriocapillaris and perfusion density from deep choroid. Associations between annual changes in the OCT-A indices and axial length and baseline refraction were also studied. Among children, significant reductions were noted only in parafoveal superficial retinal and foveal and perifoveal deep retinal layer indices over 1 year (p < 0.05). Choroidal OCT-A indices in children and both retinal and choroidal OCT-A indices in adults did not show significant changes. Myopia was associated with a larger reduction in the perifoveal retinal OCT-A indices in children, and with increases in sub-foveal and sub-parafoveal choroidal indices in adults. There were associations between OCT-A indices and axial length changes but differently in adults and children. Significant changes were noted in retinal OCT-A indices over 1 year among children but not adults. In comparison, choroidal OCT-A indices in adults and children showed a stable morphology over this period of time. [ABSTRACT FROM AUTHOR]

Understanding devices used for vision screening, including their potential utilisation and validity, will facilitate proper utilisation of this technology. The Acuidrive is a self-illuminated, hand-held, visual acuity screening device intended for use in policing, with visual acuity assessed roadside to identify drivers who may not meet vision standards for driving. The target is presented binocularly at 24 cm, and +4.00 D lenses eliminate the accommodation requirement. This study investigates its validity and applicability relative to the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart. There were 36 participants, half younger adults aged 18–30 years and half older adults aged 50–70 years. The subjects underwent binocular visual acuity testing using the Acuidrive device and an ETDRS chart displayed on a monitor. Eyes were corrected for distance using lenses in a trial frame, and additional trial lenses provided four blur levels: zero, +0.50 DS, +1.00 DS and +1.50 DS. Luminances for the devices were similar at approximately 100 cd/m2. ETDRS chart measurements were conducted both with room lighting on and off. The Acuidrive device underestimated the ETDRS visual acuity across all blur levels, with mean differences of 0.24 ± 0.07 logMAR and 0.18 ± 0.10 logMAR for room lights on and off, respectively. To predict ETDRS visual acuity of poorer than 0.34 logMAR (6/12=), a screening level of 0.50 logMAR (6/19) with the Acuidrive device provided high sensitivity and specificity (86% and 79% with lights-on, and 85% and 78% with lights-off). Visual acuity was better for the older group than the younger group by approximately 0.10 logMAR. There was an offset of 0.2 logMAR (two lines) between visual acuity measures for the Acuidrive device and an ETDRS chart. The Acuidrive device has the potential to be a viable screening tool with refinement to its construction. [ABSTRACT FROM AUTHOR]

Purpose: This study compared in vivo crystalline lens shape measurements using B‐scan images from the IOLMaster 700 with phakometry. Methods: Twenty‐four young adult participants underwent IOLMaster 700 and phakometry measurements under cycloplegia (1% cyclopentolate). The IOLMaster 700 generated B‐scan images along six meridians in 30° increments, which were analysed using custom MATLAB software to determine lens surface radii of curvature. Phakometry measurements were obtained using Purkinje images reflected from the lens surfaces. Results: The IOLMaster 700 image analysis method yielded a lower mean anterior lens surface spherical equivalent power (+6.20 D) than phakometry (+7.55 D); however, the two measurements were strongly correlated (R(21) = 0.97, p < 0.0001). The astigmatic power vectors (J0 and J45) for the anterior lens surface were significantly higher for the IOLMaster 700 measurements, with only J0 showing a significant moderate positive correlation (R(21) = 0.57, p = 0.005). For the posterior lens surface, the IOLMaster 700 measurements had a higher mean spherical power (+14.28 D) compared to phakometry (+13.70 D); however, a strong positive correlation (R(21) = 0.90, p < 0.0001) was observed. No significant correlations were noted for posterior lens surface astigmatic vectors (J0 and J45). The IOLMaster 700 estimates for the equivalent lens mean spherical power were slightly lower than those for phakometry, with a mean difference of −0.72 D, and both methods were positively correlated (R(21) = 0.94, p < 0.0001). Conclusions: The findings demonstrate that IOLMaster 700 B‐scan image analysis technique provides similar estimates of lens surface powers to phakometry. These results highlight the potential of the IOLMaster 700 to provide measurements of lens shape, informing future research and clinical use. [ABSTRACT FROM AUTHOR]

Binocular visual acuity is an important index of functional performance. Optometrists need to know how binocular visual acuity is affected by aniseikonia, and whether reduced binocular visual acuity is a marker for aniseikonia. Aniseikonia, the perception of unequal image sizes between the eyes, can occur spontaneously or can be induced after different types of eye surgery, or trauma. It is known to affect binocular vision, but there are no prior studies about how it affects visual acuity. Visual acuity was measured for 10 healthy well-corrected participants aged 18–21 years of age. Aniseikonia of up to 20% was induced in one of two ways: (1) size lenses, which provided minification of field of view in one eye of each participant and (2) polaroid filters, which allowed vectographic viewing of optotypes on a 3D computer monitor. The best corrected acuity was measured on conventional logarithmic progression format vision charts and isolated optotypes, under both induced aniseikonia conditions. Induced aniseikonia caused binocular visual acuity thresholds to increase by small but statistically significant amounts, with the largest deficit being 0.06 logMAR for 20% size differences between the eyes. Binocular visual acuity was worse than monocular visual acuity for aniseikonia of 9% and greater. Acuity measured with the vectographic presentation gave slightly higher thresholds (by 0.01 logMAR) than for those viewed with size lenses. Acuity measured with charts gave slightly higher thresholds (by 0.02 logMAR) than with isolated letters. An acuity change of 0.06 logMAR is small and may be missed in a clinical examination. Therefore, visual acuity cannot be used as a marker of aniseikonia in clinical settings. Even with very marked induced aniseikonia, binocular visual acuity remained well within standards for licen*c*sing of drivers. [ABSTRACT FROM AUTHOR]

Purpose: The Enright phenomenon describes the distortion in speed perception experienced by an observer looking sideways from a moving vehicle when viewing with interocular differences in retinal image brightness, usually induced by neutral density filters. We investigated whether the Enright phenomenon could be induced with monocular pupil dilation using tropicamide. Methods: We tested 17 visually normal young adults on a closed road driving circuit. Participants were asked to travel at Goal Speeds of 40 km/h and 60 km/h while looking sideways from the vehicle with: (i) both eyes with undilated pupils; (ii) both eyes with dilated pupils; (iii) with the leading eye only dilated; and (iv) the trailing eye only dilated. For each condition we recorded actual driving speed. Results: With the pupil of the leading eye dilated participants drove significantly faster (by an average of 3.8 km/h) than with both eyes dilated (p = 0.02); with the trailing eye dilated participants drove significantly slower (by an average of 3.2 km/h) than with both eyes dilated (p

The effect of vitamin A supplements on metabolic behavior of an oral tracer dose of [14C]β-carotene was investigated in a longitudinal test-retest design in two adults. For the test, each subject ingested 1 nmol of [14C]β-carotene (100 nCi) in an emulsified olive oil-banana drink. Total urine and stool were collected for up to 30 days; concentration-time patterns of [14C]β-carotene, [14C]retinyl esters, and [14C]retinol were determined for 46 days. On Day 53, the subjects were placed on a daily vitamin A supplement (10,000 IU/day), and a second dose of [14C]β-carotene (retest) was given on Day 74. All 14C determinations were made using accelerator mass spectrometry. In both subjects, the vitamin A supplementation was associated with three main effects: 1) increased apparent absorption: test versus retest values rose from 57% to 74% (Subject 1) and from 52% to 75% (Subject 2); 2) an ∼10-fold reduction in urinary excretion; and 3) a lower ratio of labeled retinyl ester/β-carotene concentrations in the absorptive phase. The molar vitamin A value of the dose for the test was 0.62 mol (Subject 1) and 0.54 mol (Subject 2) vitamin A to 1 mol β-carotene. Respective values for the retest were 0.85 and 0.74.These results show that while less cleavage of β-carotene occurred due to vitamin A supplementation, higher absorption resulted in larger molar vitamin A values.