Difference of central foveal thickness measurement in patients with macular edema using optical coherence tomography in different display modes.

Purpose: To assess the differences in the measurement of central foveal thickness (CFT) in patients with macular edema (ME) between two display modes (1:1 pixel and 1:1 micron) on optical coherence tomography (OCT). Design: This is a retrospective, cross-sectional study. Methods: Group A consisted of participants with well-horizontal OCT B-scan images and group B consisted of participants with tilted OCT B-scan. We manually measured the CFT under the two display modes, and the values were compared statistically using the paired t-test. Spearman's test was used to assess the correlations between the OCT image tilting angle (OCT ITA) and the differences in CFT measurement. The area under the curve (AUC) was calculated to define the OCT ITA cutoff for a defined CFT difference. Results: In group A, the mean CFT in the 1:1 pixel display mode was 420.21 ± 130.61 µm, similar to the mean CFT of 415.27 ± 129.85 µm in the 1:1 micron display mode. In group B, the median CFT in the 1:1 pixel display mode is 409.00 µm (IQR: 171.75 µm) and 368.00 µm (IQR: 149.00 µm) in the 1:1 micron display mode. There were significant differences between the two display modes with the median (IQR) absolute difference and median (IQR) relative difference of 38.00 µm (75.00 µm) and 10.19% (21.91%) (all p = 0.01). The differences in CFT measurement between the two display modes were correlated with the OCT ITA (absolute differences, r = 0.88, p < 0.01; relative differences, r = 0.87, p < 0.01). The AUC for a predefined CFT difference was 0.878 (10 µm), 0.933 (20 µm), 0.938 (30 µm), 0.961 (40 µm), 0.962 (50 µm), and 0.970 (60 µm). Conclusion: In patients with DM, when the OCT B-scan images were well-horizontal, manual CFT measurements under the two display modes were similar, but when the B-scan images were tilted, the CFT measurements were different under the two display modes, and the differences were correlated to the OCT ITA.

Case series about physiological astigmatism and the impact of pterygium surgery.

Introduction: Pterygium is a benign conjunctival fibrovascular neoformation progressively encroaching on the cornea, it can cause corneal distortion and induce astigmatism, or aggravate pre-existing physiological astigmatism, which is defined as ≤ 0.50 D and not requiring optical correction. The radical treatment of pterygium is purely surgical, with conjunctivo-limbal grafting and conjunctival autografting emerging as the surgical techniques of choice. The main objective of the study was to investigate whether pterygium surgery does not worsen the preoperative physiological astigmatism. Material and methods: This is a prospective cohort study conducted in the ophthalmology department of the Mohammed V Military Hospital in Rabat over a period of 12 months, including 43 stage II/III/IV pterygia that were operated on by conjunctival autograft by the same surgeon. First, we looked for an association between pterygium surgery and variations in astigmatism. For quantitative variables we used the Wilcoxon test. In a second step we split the file into two distinct groups according to the value of preoperative astigmatism≤ 0.5 D or >0.5 D in order to detect the impact of pterygium surgery on physiological astigmatism. Statistical analysis of the data was performed by comparing the distribution of these characteristics. Results: The median astigmatism was 1 D (0.25; 2.50). 35% of our population had preoperative astigmatism ≤0.5 D. The Wilcoxon test showed that there was a statistically significant difference between preoperative and postoperative astigmatism (p = 0.001). The paired sample T-test showed no statistically significant difference between the preoperative and postoperative outcome in the physiological astigmatism population (p = 0.53). Conclusion: Many studies have shown the benefits of pterygium excision on astigmatism, but few studies have specified the impact of this surgery on physiological astigmatism. Our study showed that pterygium surgery does not alter physiological astigmatism.

[Loiasis (African eye worm): about a case]. / Une loase oculaire: à propos d'un cas.

The purpose of our study is to report a case of loiasis producing ocular manifestations in a patient living in the Sahel region, (non-endemic area). The study involved a 25-year old man admitted to ophthalmology consultation with foreign body sensation in the right eye. Ophthalmological examination objectified a tortuous, motile, translucent worm measuring around 4cm under the bulbar conjunctiva of the right eye. After surgical non-traumatic extraction, parasitological examination confirmed the diagnosis of loiasis, a parasitosis mainly occurring in African forests. As a result of population movements, it can occur everywhere in the world. It is essential to recognize it during consultations.