Repeatability and reproducibility of Cobra HD fundus camera meibography in young adults with and without symptoms of dry eye

Purpose: The inter-session repeatability (ISR), inter-examiner reproducibility (IER) and within-subject variability (WSV) of the Cobra HD fundus camera meibographer were examined in participants with and without dry eye symptoms.Methods: Symptoms were determined based on Ocular Surface Disease Index scores (=13 being considered symptomatic), and subgroups were compared using the Mann– Whitney U- test. Images of meibomian glands (MGs) from the upper and lower right eyelids were captured by two examiners on the same day (S1) to determine IER. One examiner repeated the measurements on a second day (S2) to obtain the ISR. ISR, IER and WSV were calculated using Friedman, correlation tests and Bland and Altman analyses with mean differences (md) and 95% confidence intervals (CIs), within-subject standard deviations (Sw) and intra-class correlation coefficients (ICC).Results: The ISR experiment included 72 participants (mean age: 23 ± 5 years, range: 19–43, 36 symptomatic). Mean MG loss of the upper (S1: 13.5 ± 9.5%, S2: 12.8 ± 8.5%) and lower eyelids (S1: 7.5 ± 6.9%, S2: 7.3 ± 6.3%) was not significantly different between sessions for all participants, symptomatic and asymptomatic subgroups for both eyelids. The ISR Sw for the upper and lower eyelids was 1.3% and 1.0%; md was 0.7 ± 3.5% (CI:-6.25% to 7.62%) and 0.1 ± 2.1% (CI: -3.94% to 4.17%), respectively. The IER experiment included 74 participants (mean age: 23 ± 5 years, range: 19–43, 37 symptomatic). Mean MG loss of the upper (Examiner 1: 12.7 ± 8.2%, Examiner 2: 13.1 ± 8.0%) and lower eyelids (Examiner 1: 7.0 ± 6.2%, Examiner 2: 7.4 ± 6.2%) was not significantly different between examiners for all participants, symptomatic and asymptomatic subgroups for both eyelids. The IER ICC values were >0.86 for all conditions, Sw was 1.3% and 1.2%, with a md of -0.4 ± 3.2% (CI: -6.65% to 5.90%) and -0.4 ± 2.9% (CI: -6.15% to 5.31%), respectively. The WSV Sw values were 0.89 for both eyelids, examiners and experimental sessions.Conclusions: The Cobra HD fundus camera demonstrates good repeatability, reproducibility and low WSV, and is a reliable clinical instrument for meibography.Peer ReviewedPostprint (published version

Topical review of the relationship between contact lens wear and meibomian gland dysfunction

Contact lens (CL) wearers often suffer from ocular discomfort, which leads to cessation of CL wear. About 30% to 50% of CL wearers complain of dry eye (DE) symptoms. Meibomian gland dysfunction (MGD) is considered the most common cause of evaporative DE. Numerous studies have investigated whether CL wear might affect the meibomian glands. This manuscript reviews studies examining the relationship between CL use and MGD. A PubMed database search was conducted for studies published between 1980-2021 with one or a combination of search terms related to “meibomian gland”, “meibomian gland dysfunction”, “contact lens”, and/or “dry eye”. Of the 115 papers reviewed, 22 articles were identified that examined the association between CL and MGD. Fifteen showed that CL wear affects the morphology and function of meibomian glands (MGs), while seven reported no significant impact of CL wear on MGs. This review provides an overview of these studies, emphasizing the diagnostic tests of MGD and conclusions. The review highlights the need for longitudinal prospective large cohort studies with control non- CL wearers to clarify the ambiguous relationship between MGD and CL wear, with special attention to varying CL material and wear times in order to identify the long-term impact of CLs on MG.Peer ReviewedPostprint (author's final draft

Mechanisms of perceptual learning of depth discrimination in random dot stereograms.

Perceptual learning is a training induced improvement in performance. Mechanisms underlying the perceptual learning of depth discrimination in dynamic random dot stereograms were examined by assessing stereothresholds as a function of decorrelation. The inflection point of the decorrelation function was defined as the level of decorrelation corresponding to 1.4 times the threshold when decorrelation is 0%. In general, stereothresholds increased with increasing decorrelation. Following training, stereothresholds and standard errors of measurement decreased systematically for all tested decorrelation values. Post training decorrelation functions were reduced by a multiplicative constant (approximately 5), exhibiting changes in stereothresholds without changes in the inflection points. Disparity energy model simulations indicate that a post-training reduction in neuronal noise can sufficiently account for the perceptual learning effects. In two subjects, learning effects were retained over a period of six months, which may have application for training stereo deficient subjects

Can the Red-Green Duochrome Test Be Used Prior to Correcting the Refractive Cylinder Component?

Purpose A primary task of the eye care professional is determining the refraction, or optical correction, of a patient. The duochrome red-green test is a standard tool for verification of the final refraction. Traditionally, it is recommended for use both prior to and subsequent to determining the cylindrical or astigmatic component of the refraction. In order for it to be effective when used before correcting the cylinder it is necessary that the COLC (Circle of Least Confusion) be on the retina. This study examined whether it is necessarily true that the duochrome response in uncorrected astigmatism will be as trust-worthy as it is with corrected cylinders. Methods The red-green examination was performed monocularly under the following three conditions: a. fully corrected refraction for the subgroup of eyes that had spherical refractions and for the subgroup of eyes with sphero-cylindrical refractions. b. best sphere-only correction without cylinder correction in sphero-cylindrical eyes c. an induced cylinder error in spherical eyes. The interval between the last “red” response and the first “green” response for the right eyes as a group and separately for the physiological cylinder and induced cylinder correction sub-groups was calculated and compared using a paired, two-tailed t-test. Results The intervals between “red” and “green” responses were not significantly different in the population as a whole and in the uncorrected physiological cylinder and induced cylinder subgroups examined. Conclusion Based on the finding that the interval of red-green equality with fully corrected cylinder and without the cylindrical correction are not significantly different, the red-green duochrome test can indeed be used both before and after cylindrical correction

Validación de los parámetros de refracción y segmento anterior mediante una nueva plataforma multi-diagnóstica (VX120)

Background: The VX120 (Visionix Luneau, France) is a novel multi-diagnostic platform that combines Hartmann–Shack based autorefraction, Placido-disk based corneal-topography and anterior segment measurements made with a stationary-Scheimpflug camera. We investigate the agreement between different parameters measured by the VX120 with accepted or gold-standard techniques to test if they are interchangeable, as well as to evaluate the repeatability and reproducibility. Methods: The right-eyes of healthy subjects were included in the study. Autorefraction of the VX120 was compared to subjective refraction. Agreement of anterior segment parameters was compared to the Sirius (CSO, Italy) including autokeratometry, central corneal thickness (CCT), iridiocorneal angle (IA). Inter and intra-test repeatability of the above parameters was assessed. Results were analyzed using Bland and Altman analyses. Results: A total of 164 eyes were evaluated. The mean difference between VX120 autorefraction and subjective refraction for sphere, spherical equivalent (SE), and cylinder was 0.01 ± 0.43 D, 0.14 ± 0.47 D, and −0.26 ± 0.30 D, respectively and high correlation was found to all parameter (r > 0.75) except for J45 (r = 0.61). The mean difference between VX120 and the Sirius system for CCT, IA, and keratometry (k1 and k2) was −3.51 ± 8.64 μm, 7.6 ± 4.2°, 0.003 ± 0.06 mm and 0.004 ± 0.04 mm, respectively and high correlation was found to all parameter (r > 0.97) except for IA (r = 0.67). Intrasession repeatability of VX120 refraction, CCT, IA and keratometry yielded low within-subject standard deviations. Inter-session repeatability showed no statistically significant difference for most of the parameters measured. Conclusions: The VX120 provides consistent refraction and most anterior segment measurements in normal healthy eyes, with high levels of intra and inter-session repeatability.Antecedentes: VX120 (Visionix Luneau, Francia) es una plataforma multi-diagnóstico novedosa que combina la auto-refracción basada en Hartmann–Shack, la topografía corneal mediante discos de Plácido, y las mediciones del segmento anterior realizadas mediante cámara de Scheimpflug. Analizamos la concordancia entre los diferentes parámetros medidos por VX120 con las técnicas aceptadas o de referencia, para probar si eran intercambiables, y evaluamos la repetibilidad y reproducibilidad. Métodos: Se incluyeron en el estudio los ojos derechos de sujetos sanos. Se comparó la auto-refracción de VX120 con la refracción subjetiva. La concordancia de los parámetros del segmento anterior se comparó con la del sistema Sirius (CSO, Italia), incluyendo autoqueratometría, espesor corneal central (ECC) y ángulo iridiocorneal (AI). Se valoró la repetibilidad inter e intra-prueba de los parámetros anteriores. Los resultados se analizaron mediante el método de Bland–Altman. Resultados: Se evaluó un total de 164 ojos. La diferencia media entre la auto-refracción de VX120 y la refracción subjetiva para esfera, equivalente esférico (EE), y cilindro fue de 0,01±0,43D, 0,14±0,47D y −0,26±0,3D, respectivamente, encontrándose una elevada correlación entre todos los parámetros (r>0,75) excepto para J45 (r=0,61). La diferencia media entre VX120 y el sistema Sirius para ECC, AI, y queratometría (k1 y k2) fue de -3,51±8,64 μm, 7,6±4,2°, 0,003±0,06 mm y 0,004±0,04 mm, respectivamente, encontrándose una elevada correlación entre todos los parámetros (r>0,97) excepto para AI (r=0,67). La repetibilidad intra-sesión de la refracción VX120, ECC, AI y queratometría reflejó desviaciones estándar bajas entre sujetos. La repetibilidad inter-sesión no reflejó una diferencia significativa para la mayoría de los parámetros medidos. Conclusiones: VX120 aporta medidas consistentes de refracción y de la mayoría de las mediciones del segmento anterior en ojos sanos normales, con elevados niveles de repetibilidad intra e inter-sesión

Bar graph of red-green interval.

<p>The X axis is subject number and Y axis is the interval between “red” and “green” responses in diopters. Blue is with spherical correction only; red is with spherical and cylindrical correction.</p

Subject demographic and optometric details.

<p>Subject demographic and optometric details.</p

A survey of the criteria for prescribing in cases of borderline refractive errors

Purpose: This research investigated the reported optometric prescribing criteria of Israeli optometrists. Methods: An online questionnaire based on previous studies was distributed via email and social networking sites to optometrists in Israel. The questionnaire surveyed the level of refractive error at which respondents would prescribe for different types of refractive error at various ages with and without symptoms. Results: 124 responses were obtained, yielding a response rate of approximately 12–22%, 92% of whom had trained in Israel. For all refractive errors, the presence of symptoms strongly influenced prescribing criteria. For example, for 10–20 year old patients the degree of hyperopia for which 50% of practitioners would prescribe is +0.75 D in the presence of symptoms but twice this value (+1.50 D) in the absence of symptoms. As might be expected, optometrists prescribed at lower degrees of hyperopia for older compared with younger patients. There was a trend for more experienced practitioners to be less likely to prescribe for lower degrees of myopia and presbyopia. Practitioner gender, country of training, the type of practice environment, and financial incentives were not strongly related to prescribing criteria. Conclusions: The prescribing criteria found in this study are broadly comparable with those in previous studies and with published prescribing guidelines. Subtle indications suggest that optometrists may become more conservative in their prescribing criteria with experience