Inner Retinal Microvasculature With Refraction in Juvenile Rhesus Monkeys.

Purpose: To characterize inner retinal microvasculature of rhesus monkeys with a range of refractive errors using optical coherence tomography angiography. Method: Refractive error was induced in right eyes of 18 rhesus monkeys. At 327 to 347 days of age, axial length and spherical equivalent refraction (SER) were measured, and optical coherence tomography and optical coherence tomography angiography scans (Spectralis, Heidelberg) were collected. Magnification-corrected metrics included foveal avascular zone area and perfusion density, fractal dimension, and lacunarity of the superficial vascular complex (SVC) and deep vascular complex (DVC) in the central 1-mm diameter and 1.0- to 1.5-mm, 1.5- to 2.0-mm, and 2.0- to 2.5-mm annuli. Pearson correlations were used to explore relationships. Results: The mean SER and axial length were 0.78 ± 4.02 D (-7.12 to +7.13 D) and 17.96 ± 1.08 mm (16.41 to 19.93 mm), respectively. The foveal avascular zone area and SVC perfusion density were correlated with retinal thickness for the central 1 mm (P < 0.05). SVC perfusion density of 2.0- to 2.5-mm annulus decreased with increasing axial length (P < 0.001). SVC and DVC fractal dimensions of 2.0- to 2.5-mm were correlated with axial length and SER, and DVC lacunarity of 1.5- to 2.0-mm annulus was correlated with axial length (P < 0.05). Conclusions: Several inner retinal microvasculature parameters were associated with increasing axial length and SER in juvenile rhesus monkeys. These findings suggest that changes in retinal microvasculature could be indicators of refractive error development. Translational Relevance: In juvenile rhesus monkeys, increasing myopic refraction and axial length are associated with alterations in the inner retinal microvasculature, which may have implications in myopia-related changes in humans.

Repeatability of retinal and choroidal optical coherence tomography angiography indices in healthy children and young adults.

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.

Repeatability and agreement of the MYAH and Lenstar.

SIGNIFICANCE: Validation of new biometry instruments against the gold standard and establishing repeatability are important before being utilized for clinical and research applications. PURPOSE: This study aimed to investigate intersession repeatability of the MYAH optical biometer and corneal topographer and examine agreement with the Lenstar LS900 optical biometer in healthy young adults. METHODS: Forty participants (mean age, 25.2 ± 3.1 years) presented for two visits, 2 to 4 days apart. At each visit, measurements for right eyes were collected with the MYAH and Lenstar LS 900 and included axial length, corneal power, white-to-white distance, and pupil diameter. Bland-Altman analysis was used to assess the intrasession agreement between the MYAH and Lenstar for each parameter and intersession repeatability for the two devices. For each device, coefficient of variation and intraclass correlation coefficient were calculated, and paired t tests between visits were performed to assess intersession repeatability. RESULTS: Good agreement (mean difference [95% limits of agreement]) between the MYAH and Lenstar was found for axial length (-0.01 [-0.07 to 0.04] mm), corneal power (-0.02 D [-0.15 to 0.19 d]), white-to-white distance (-0.13 [-0.43 to 0.17] mm), and pupil diameter (-0.27 [-0.79 to 1.33] mm). The limits of agreement, coefficient of variations, and intraclass correlation coefficients for MYAH-measured parameters were -0.04 to 0.04, 0.06%, and >0.99 for axial length; -0.24 to 0.19, 0.18%, and >0.99 for corneal power; -1.05 to 1.15, 0.57%, and 0.96 for white-to-white distance; and -0.17 to 0.21, 7.0%, and 0.76 for pupil diameter, with no significant difference between visits (p>0.05 for all), indicating good intersession repeatability. Similar intersession repeatability was also noted for Lenstar. CONCLUSIONS: Findings show good intersession repeatability of the MYAH and good agreement with the Lenstar for axial length, corneal power, and white-to-white distance in young adults. Pupil diameter was more variable, likely due to the dynamic nature of the pupil. This study provides validation and supports the use of the MYAH for ocular biometry.

Vision screening using the Acuidrive device.

CLINICAL RELEVANCE: Understanding devices used for vision screening, including their potential utilisation and validity, will facilitate proper utilisation of this technology. BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Changes in retinal and choroidal optical coherence tomography angiography indices among young adults and children over 1 year.

CLINICAL RELEVANCE: 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. BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Diurnal changes in choroidal optical coherence tomography angiography indices over 24 hours in healthy young adults.

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 < 0.05) were observed in most of the choroidal OCT-A indices excluding sub-perifoveal flow deficit number, with peaks observed between 2 to 6 AM. For myopes, peaks occurred significantly earlier (3-5 h), and the diurnal amplitude was significantly greater for sub-foveal flow deficit density (P = 0.02) and deep choroidal perfusion density (P = 0.03) compared with non-myopes. Choroidal thickness also showed significant diurnal changes (P < 0.05) with peaks between 2 to 4 AM. Significant correlations were found between diurnal amplitudes or acrophases of choroidal OCT-A indices and choroidal thickness, intraocular pressure, and systemic blood pressure. This provides the first comprehensive diurnal assessment of choroidal OCT-A indices over 24 h.

Changes in Retinal Optical Coherence Tomography Angiography Indexes Over 24 Hours.

Purpose: To evaluate changes in the retinal microvasculature of young adults over 24 hours using optical coherence tomography angiography (OCT-A). Methods: Participants (n = 44, mean age 23.2 ± 4.1 years, 24 myopes and 20 nonmyopes) with normal ophthalmological findings were recruited. Two macular OCT-A and OCT scans, systemic blood pressure, intraocular pressure (IOP), and biometry measurements were taken every four hours over 24 hours. Superficial and deep retinal layer en face images were analyzed to extract magnification-corrected vascular indexes using image analysis including foveal avascular zone metrics, vessel density, and perfusion density for the foveal, parafoveal, and perifoveal zones. Results: Significant diurnal variations (P < 0.001) were observed in the vessel and perfusion density in the three superficial retinal layer regions, with acrophase between 4:30 PM and 8:30 PM. Only foveal and parafoveal regions of the deep retinal layer exhibited significant diurnal variations with acrophase between 9 AM and 3 PM. Myopes and nonmyopes had different acrophases but not amplitudes in the parafoveal perfusion density of superficial retinal layer (P = 0.039). Significant correlations were observed between diurnal amplitudes or acrophases of superficial retinal layer indexes and systemic pulse pressure, IOP, axial length and retinal thickness. Conclusions: This study shows, for the first time, that significant diurnal variation exists in OCT-A indexes of macular superficial and deep retinal layer over 24 hours and were related to variations in various ocular and systemic measurements. Myopes and nonmyopes showed differences in the timing but not in amplitude of the superficial retinal layer parafoveal perfusion density variations but not in deep retinal layer.

Induced Refractive Error Changes the Optical Coherence Tomography Angiography Transverse Magnification and Vascular Indices.

PURPOSE: To assess the effect of changing anterior eye refractive power with contact lenses on the transverse magnification of en face images and associated vascular indices from optical coherence tomographic angiography (OCT-A). DESIGN: Prospective crossover study. METHODS: Spherical soft contact lenses (-6 diopter [D] to +6 D in 2 D steps) were used to induce anterior eye refractive power changes in 11 healthy young adults and 3 × 3-mm macular scans were captured using OCT-A (Zeiss AngioPlex, software version 11.0; Cirrus HD-OCT 5000, Carl Zeiss Meditec Inc). Image transverse magnification was predicted based on refraction and biometry measurements and compared with empirical changes in the en face images measured with image analysis. Linear regression analysis was performed to assess the relationship between induced refractive ametropia and foveal avascular zone (FAZ) area, perimeter, circularity, and vessel density and perfusion density. RESULTS: The predicted transverse magnification was linearly related to induced refractive ametropia and to the empirical transverse magnification changes (average slope: 1.02, 95% CI: 0.90-1.34). All the OCT-A indices showed linear relationships with induced refractive ametropia (P < .05) with the 12 D tested range altering the indices by 7% to 12%. After correcting for transverse magnification, all OCT-A indices except FAZ area were linearly related to induced refractive ametropia (P < .05) and were reduced to 1% to 9%. CONCLUSIONS: This study is the first to show that induced refractive ametropia can affect OCT-A image magnification and indices. These changes are clinically important and need to be considered along with biometry effects when interpreting OCT-A indices. Transverse magnification changes can affect the ability of OCT-A to precisely measure linear dimensions of blood vessels.

Optometry students’ perspective on optometry in suburban Western India: A qualitative study

Purpose: Optometry has been an established profession in India for 60 years. Despite this, students who choose this course may have misconceptions and unrealistic expectations about the profession. The goal of this study is to understand the perceptions about optometry among optometry students, prior to and during their studies.MethodsA snap-shot narrative qualitative study using a semi-structured open-ended questionnaire was designed to understand the perception of optometry. Optometry students and educators from three suburban colleges were invited to participate. Forty-one participants took part in 24 in-depth interviews and 5 focus groups; of those 32 were undergraduate optometry students and 9 were optometry educators. Interviews and focus groups were audio-recorded, transcribed, coded, and analyzed.ResultsThree major themes emerged: retrospective perception of optometry, current perception and strategies to improve awareness level. All the participants mentioned that there was a considerable lack of awareness about optometry in society. None of the students stated that they chose optometry as their first choice of professional education. Most students expressed that they were provided with ample exposure during the curriculum to understand the scope of optometry. Various strategies were recommended to improve the level of awareness of optometry.ConclusionsThe current study highlights the lack of awareness and knowledge of optometry among the students while enrolling in the course. Knowledge about the scope of optometry practice among optometry students improved after extensive education and clinical exposure. Improving the awareness level of the profession will improve the quality of students entering the profession. (AU)

Optometry students' perspective on optometry in suburban Western India: A qualitative study.

PURPOSE: Optometry has been an established profession in India for 60 years. Despite this, students who choose this course may have misconceptions and unrealistic expectations about the profession. The goal of this study is to understand the perceptions about optometry among optometry students, prior to and during their studies. METHODS: A snap-shot narrative qualitative study using a semi-structured open-ended questionnaire was designed to understand the perception of optometry. Optometry students and educators from three suburban colleges were invited to participate. Forty-one participants took part in 24 in-depth interviews and 5 focus groups; of those 32 were undergraduate optometry students and 9 were optometry educators. Interviews and focus groups were audio-recorded, transcribed, coded, and analyzed. RESULTS: Three major themes emerged: retrospective perception of optometry, current perception and strategies to improve awareness level. All the participants mentioned that there was a considerable lack of awareness about optometry in society. None of the students stated that they chose optometry as their first choice of professional education. Most students expressed that they were provided with ample exposure during the curriculum to understand the scope of optometry. Various strategies were recommended to improve the level of awareness of optometry. CONCLUSIONS: The current study highlights the lack of awareness and knowledge of optometry among the students while enrolling in the course. Knowledge about the scope of optometry practice among optometry students improved after extensive education and clinical exposure. Improving the awareness level of the profession will improve the quality of students entering the profession.

Awareness and knowledge of diabetic retinopathy and associated factors in Goa: A hospital-based cross-sectional study.

Purpose: To assess the awareness and knowledge about diabetic retinopathy (DR) and associated factors among patients visiting the tertiary health center in Goa. Methods: A cross-sectional descriptive study was conducted using a standard predesigned and pretested closed-ended structured questionnaire to assess the awareness, knowledge, attitude and practice about DR among patients visiting a tertiary health center. Results: Three hundred and fifty-eight subjects participated in the study. Only 125 (34.9% [95% CI: 30.0-40.1]) subjects were aware of DR and 122 (34.1% [95% CI: 29.2-39.2]) had adequate knowledge about DR. Awareness and knowledge of DR were significantly high among the subjects who completed college level of education (66.7%, OR = 2.78; 95% CI: 1.73-4.48, P < 0.001 and 55.9%, OR = 3.92; 95% CI: 2.41-6.38, P < 0.001) and who spoke English (52.5%, OR = 3.37; 95% CI: 2.14-5.30, P < 0.001 and 50.4%, OR = 3.26; 95% CI: 2.07-5.14, P < 0.001). Christians reported better knowledge about DR compared to other religions (48.8%, OR = 2.27; 95% CI: 1.38-3.75, P = 0.005). Negative association was noted between the knowledge of DR and presence of diabetes (29.4%, OR = 0.64; 95% CI: 0.41-0.99, P = 0.048). The practice pattern was strongly associated (OR = 7.47; 95% CI: 4.51-12.38, P < 0.001) with the knowledge of DR. Attitude was not influenced by any of the factors. Conclusion: We found that awareness and knowledge about DR were unsatisfactory; literacy contributed significantly toward it. These findings also suggest that there is an immediate need to enhance the awareness and knowledge of diabetic eye diseases in order to reduce the burden of visual impairment.

Awareness and knowledge on eye donation among Allied Health Sciences, medical, and nursing students in Goa.

PURPOSE: To assess the awareness and knowledge on eye donation among students of Allied Health Sciences (AHS), medical, and nursing. METHODS: A cross-sectional descriptive study was conducted using a standard predesigned and pretested closed-ended structured questionnaire based on eye donation to obtain information about awareness and knowledge from AHS, medical, and nursing students of Goa. RESULTS: Three hundred and forty participants participated in the study. The majority of the participants [97.9% (95% CI: 95.8-99.2)] were aware of the existence of eye donation. Mass media (62.9%) was the foremost source of information. However, only 145 [42.6% (95% CI: 37.3-48.1)] participants were willing to donate their eyes. AHS, medical, and nursing students stood apart significantly in their awareness and knowledge. Only 60 [17.6% (95% CI: 13.7-22.1)] participants were aware that the whole eye can be removed from the donor while 215 [63.2% (95% CI: 57.9-68.4)] were wrongly aware that the cornea can be removed separately. Awareness about eye donation was not associated with willingness to donate eyes. CONCLUSIONS: Although awareness regarding eye donation was satisfactory, there was lack of willingness to donate eyes. There is a need to bridge the gap between eye bank and donors.