Analysis of Microvasculature in Children Recovered from COVID-19 Using Swept-Source OCT/OCTA Technology.

PURPOSE: To analyze structural and vascular changes of the retina and choroid in pediatric patients with coronavirus disease 2019 (COVID-19) using optical coherence tomography (OCT)/OCT angiography (OCTA). METHODS: This comparative cross-sectional study consists of the COVID-19 group including pediatric COVID-19 patients and the control group including healthy children. Vessel density (VD), central macular thickness,, and choroidal thickness (ChT) measurements were performed using swept-source OCT/OCTA 12 weeks after the recovery from COVID-19. RESULTS: The mean VD measurements in the central fovea and nasal quadrants of all three retinal layers and choriocapillaris showed insignificantly lower values in the COVID-19 group when compared to the control group (0:002 < p < 0:05 for all). Similar to VD measurements, insignificant lower ChT measurements were obtained in the central fovea and nasal points in the COVID-19 group. CONCLUSION: OCTA can be used as a non-invasive and valid biomarker in the assessment of early microvascular dysfunction associated with COVID-19.

Optical biometric measurements in patients with previous COVID-19 treatment.

Background: We aimed to compare optical biometric measurements using optical biometry in patients with previously received COVID-19 treatment and a control group. Methods: In this cross-sectional study, patients with previously received COVID-19 treatment formed the COVID-19 group and age- and sex-matched healthy participants formed the control group. Optical biometric measurements including keratometry, corneal astigmatism, astigmatic axis, central corneal thickness, anterior chamber depth, and axial length were made using a Nidek optical biometer (AL-Scan; Nidek Co., Ltd., Japan). Results: Measurements of keratometry (p = 0.79), corneal astigmatism (p = 0.41), axial length (p = 0.96), anterior chamber depth (p = 0.59), and central corneal thickness (p = 0.37) were similar between the COVID-19 and control groups. The astigmatic axis type taken from 2.4 mm of the cornea showed significant difference between the two groups (p = 0.02, χ2), while the measurements taken from 3.3 mm of the cornea were similar (p = 0.10, χ2). In the subgroup analysis, axial length, anterior chamber depth, and central corneal thickness measurements were found to be statistically significantly higher in male patients of the COVID-19 group (p = 0.02; p = 0.001; p = 0.02, t test). Conclusion: The changes in optical biometric measurements found in our study were due to the fact that COVID-19 is more frequent and severe in males, SARS-CoV­2 can attach to the cornea via ACE­2 receptors, and favipiravir can reach the aqueous humor. To our knowledge, there is no study on this subject to date, and therefore more research is needed to shed light on this topic.

A Pediatric COVID-19 Study: Retinal Nerve Fiber Layer, Ganglion Cell Layer, and Alterations in Choroidal Thickness in Swept-Source OCT Measurements.

PURPOSE: To investigate early covid measurements of central macular thickness (CMT), retinal nerve fiber layer (RNFL), ganglion cell layer (GCL) thickness, and choroidal thickness (ChT) in children recovered from coronavirus disease 2019 (COVID-19). METHODS: This cross-sectional study was carried out 4 weeks after completed COVID-19 treatment. The diagnosis of the Alpha variant COVID-19 was made by the polymerase chain reaction test after prediagnosis with clinical, laboratory, and radiological findings. A total of 46 children were included in the study. Pediatric patients who received COVID-19 treatment comprised the COVID-19 group (24 children), and healthy children were enrolled in the control group (22 children). Only the right eyes of the participants were enrolled in the study. All pediatric patients in the COVID-19 group required hospitalization without the need for intubation. Swept-source optical coherence tomography (SS-OCT) was used to measure CMT, RNFL, and GCL thickness, and ChT measurements. RESULTS: The COVID-19 and control groups had similar mean values of visual acuity, intraocular pressure, spherical equivalent, axial length, and CMT (p > 0.05 for all). RNFL thickening, GCL, and choroidal thinning were observed in all SS-OCT measurements of COVID-19 children. However, RNFL thickening was significant only in the global and nasal peripapillary quadrants. GCL thinning was significant in the nasal/inferior sector (p < 0.002 for all). Some significant correlations were observed between the mean levels of inflammatory markers and OCT measurements (p < 0.002). CONCLUSION: This study may be among the first reports of SS-OCT examination of COVID-19 children. OCT measurements showed changes in retinal and ChT in the COVID-19 children as in adult patients.

Analysis of swept-source optical coherence tomography angiography measurement alterations in adult patients recovered from COVID-19.

CLINICAL RELEVANCE: Vessel density (VD) measurements obtained using swept-source optical coherence tomography angiography (SS-OCTA) of the retinal layers and choriocapillaris have the capacity to demonstrated retinal changes in COVID-19 patients. BACKGROUND: To investigate VD changes in the retinal layers and choroid using SS-OCTA in patients recovered from COVID-19. METHODS: This cross-sectionally designed study was conducted in a single eye centre. The diagnosis of COVID-19 disease was confirmed by a polymerase chain reaction test. Patients who had fully recovered from COVID-19 served as the COVID-19 group, and the control group comprised age- and gender-matched healthy subjects. VD measurements in the superficial and outer retina layers and the choriocapillaris were performed using SS-OCTA. RESULTS: VD measurements in the central fovea and all quadrants of superficial and deep retinal layers, and the choriocapillaris, showed a significant decrease in the COVID-19 group (P < 0.05 for all) compared to the control group. Significant reductions in VD measurements were more prominent in the choriocapillaris when compared to the retinal layers. Mean ferritin and C-reactive protein (CRP) concentrations showed negative correlations with VD measurements in certain quadrants of the deep retinal layer and choriocapillaris. CONCLUSION: VD reductions occur the superficial and deep retinal layers and choriocapillaris in patients with pre-existing COVID-19. These results suggested the use of SS-OCTA as a microvascular biomarker and an auxiliary technique for the diagnosis and follow-up of COVID-19.

Assessment of Retinal Neurodegeneration and Choroidal Thickness in COVID-19 Patients Using Swept-Source OCT Technology.

PURPOSE: To analyze the central macular thickness (CMT), retinal nerve fiber layer thickness (RNFLT), ganglion cell layer thickness (GCLT), and choroidal thickness (ChT) measurements in patients with coronavirus disease 2019 (COVID-19). METHODS: The study was conducted cross-sectionally 4 weeks after the completed treatment of COVID-19. The diagnosis of COVID-19 was based on the polymerase chain reaction test and/or clinical and radiological findings. The patients with treated COVID-19 were enrolled in the COVID-19 group; age- and sex-matched healthy participants served as the control group. All patients in the COVID-19 group were hospitalized and treated with favipiravir, moxifloxacin, and heparin without the requirement for intubation. The measurements of CMT, RNFLT (in four quadrants), GCLT (in six sectors of two different boundaries), and ChT (in five locations) were performed by swept-source optical coherence tomography (SS-OCT). RESULTS: Similar visual acuity (p = 0.582) and intraocular pressure (p = 0.766) values were observed between the COVID-19 and control groups. Regarding SS-OCT measurements, all mean CMT, RNFLT (in four quadrants), GCLT (in six sectors of two different boundaries), and ChT (in five locations) values were similar in the COVID-19 and control groups (p > 0.05 for all). In the COVID-19 group, a statistically significant negative correlation was noted between the mean ferritin level and temporal RNFLT (r = - 0.378, p = 0.014) and a positive correlation was observed between the mean ferritin level and nasal RNFLT (r = + 0.371, p = 0.016). CONCLUSION: SS-OCT measurements showed no retinal neurodegenerative and choroidal thickness alterations in COVID-19 patients. Nonsignificant results might be due to the examination of the patients in the early period of the COVID-19 after the treatment. Therefore, late period OCT measurements should be reviewed with new studies in the future.

Comparison of central corneal thickness measurements using different imaging devices and ultrasound pachymetry.

PURPOSE: To compare central corneal thickness (CCT) measurements obtained by the AL-Scan, Lenstar LS900, Galilei, and ultrasound pachymetry (UP) in normal and cataractous eyes. METHODS: Eighty eyes of healthy subjects were included in the study. Each subject was assessed by four different methods of measurements using the AL-Scan, Lenstar LS900, Galilei, and UP by a single examiner. To assess the intraobserver repeatability, three consecutive measurements were taken for the AL-Scan. RESULTS: The mean CCT [± standard deviation (SD)] for the AL-Scan, Lenstar LS900, Galilei, and UP were 554.6 ± 30.9 µm, 542.9 ± 31.3 µm, 570.7 ± 30 µm, and 552.7 ± 32.8 µm, respectively. The differences between pairs of mean CCT for the methods are statistically significant for the pairs of Galilei-UP, AL-Scan-Galilei, and Lenstar LS900-Galilei. Bland-Altman plots showed that AL-Scan-UP have the closest agreement, followed by Lenstar-UP and AL-Scan-Lenstar. Galilei was found to have the poorest agreement with the other three methods. The intraobserver repeatability of the AL-Scan was very good with an intraclass correlation coefficient (ICC) of 0.980. CONCLUSION: We found that CCT measurements between the AL-Scan-UP, Lenstar LS900-UP, and AL-Scan-Lenstar LS900 showed very strong correlation and comparable agreement. AL-Scan-UP showed the closest agreement and these devices can be used interchangeably in clinical practice. Galilei significantly showed higher value of CCT compared to other methods. It was also observed that the Al-Scan had excellent intraobserver repeatability.

Comparison of Anterior Segment Measurements with Optical Low-coherence Reflectometry and Partial-coherence Interferometry Optical Biometers.

AIMS: To evaluate a new noncontact optical biometer using partial-coherence interferometry and to compare the clinical measurements with those obtained from the device using optical low-coherence reflectometry (OLCR). SETTING AND DESIGN: Ondokuz Mayis University, Samsun, Turkey. Nonrandomized, prospective clinical trial. SUBJECTS AND METHODS: The study was performed on the healthy phakic eyes of volunteers in the year 2014. Measurements of axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), mean keratometry (K), and white-to-white (WTW) measurements obtained with the low-time coherence interferometry (LTCI) were compared with those obtained with the OLCR. STATISTICAL ANALYSIS USED: The results were evaluated using Bland-Altman analyses. The differences between both methods were assessed using the paired t-test, and its correlation was evaluated by Pearson's coefficient. RESULTS: We examined seventy participants with a mean age of 33.06 (±9.7) (range: 19-53) years. AL measurements with LTCI and OLCR were 23.7 (±1.08) mm and 23.7 (±1.1) mm, respectively. ACD was 3.6 (±0.4) mm and 3.5 (±0.4) mm for LTCI and OLCR, respectively. The mean CCT measurements for both devices were 533 (±28) mm and 522 (±28) mm, respectively. The mean K readings measurements for LTCI and OLCR were 43.3 (±1.5) D and 43.3 (±1.5) D, respectively. The mean WTW distance measurements for both devices were 12.0 (±0.5) mm and 12.1 (±0.5) mm, respectively. CONCLUSIONS: Measurements with LTCI correlated well with those with the OLCR. These two devices showed good agreement for the measurement of all parameters.

The effect of pupil dilation on AL-Scan biometric parameters.

The purpose of this study was to investigate the effects of pupil dilation on the parameters of the AL-Scan (Nidek Co., Ltd, Gamagori, Japan). We compared the measurements of axial length (AL), anterior chamber depth (ACD), central corneal keratometry reading, pupil diameter, and intraocular lens (IOL) power of 72 eyes of 72 healthy volunteers and patients scheduled for cataract surgery before and 45 min after instillation of cyclopentolate hydrochloride 1 % using the AL-Scan. Intraobserver repeatability was assessed by taking three consecutive recordings of ACD and AL. Only ACD readings were significantly different between predilation and postdilation (P < 0.001). The difference of the other measurements between two sessions was not statistically significant (P > 0.001). Only two cases in the study demonstrated changes in IOL power higher than 0.5 D. The intraobserver repeatability of both devices was good (CV values for ACD and AL were 0.16 and 0.20 %, respectively). Dilated pupil size did not affect the measurement of IOL power using the A-Scan optical biometer, but increase in ACD after dilation should be taken into account when performing refractive surgeries in which ACD is very important such as phakic anterior chamber IOL implantation.