Purpose: Little is known about contact lens (CL) use in young generation. This study aimed to investigate the patterns, behavior and knowledge of CL wear and care in Thai university students. Methods: A cross-sectional study using online questionnaires was conducted during July 2019 to February 2020 in two Rajabhat universities, Bangkok, Thailand. Participant characteristics, CL information, knowledge and behaviors were collected. Factors associated with poor behaviors and CL-related corneal ulcers were analyzed using logistic regression. Results: Of 493 students participating in the survey, 336 students (66.78%) were current CL users and completed the questionnaires. Mean age was 19.2 ± 1.4 years with female predominance (80.36%). All students wore soft CL with a major replacement schedule of monthly disposable (90.18%). Good CL wear and care behaviors were found in 190 students (56.55%). The most common poor CL behavior and poor CL knowledge were CL overuse (44.64%) and sleeping with lenses (31.85%), respectively. There were no correlations between behaviors and knowledge (r = 0.03). Purchasing lens from internet, wearing experience over one year, and long wear duration (> 12 hours) were significantly associated with poor CL behavior. Male gender and swimming with lens were significantly associated with history of corneal ulcers. Conclusion: The study pointed out a low compliance of CL wear and care in Thai university students. Good CL practices, awareness of CL-related complications and purchasing place should be carefully informed and regularly stressed to minimize preventable visual damage in young population.

Purpose To quantify the changes of subbasal nerve plexus in patients with limbal stem cell deficiency (LSCD) using in vivo laser scanning confocal microscopy. Design: Retrospective cross-sectional comparative study Methods Confocal images of 51 eyes of 37 patients with LSCD collected between 2010 and 2015 by the Heidelberg Retina Tomograph III Rostock Corneal Module Confocal Microscope. Two independent observers evaluated the scans of the central cornea. Seventeen normal eyes of 13 patients served as controls. Total subbasal nerve density (SND), density of long nerves (i.e., nerves 200 μm or longer) and the degree of tortuosity were quantified. Results The mean (± SD) total SND and long nerve density were 48.0 ± 34.2 nerves/mm2 and 9.7 ± 10.9 nerves/mm2, respectively, in all eyes with LSCD and 97.3 ± 29.9 nerves/mm2 and 35.3 ± 25.3 nerves/mm2, respectively, in eyes of the control group (P<0.001 for both comparisons). Compared with SND in control subjects, SND was reduced by 34.9% in the early stage, 54.0% in the intermediate stage, and 73.5% in the late stage of LSCD. The degrees of nerve tortuosity were significantly greater in patients with LSCD than in control subjects and differed among the early, intermediate, and late stages of LSCD. Reductions in total SND and long nerve density were positively correlated with the severity of LSCD. Conclusions Reductions in total SND and long nerve density were accompanied by increases in nerve tortuosity in eyes with LSCD. These parameters could be used as quantifiable measures of LSCD severity.

Purpose: To grade the severity of limbal stem cell deficiency (LSCD) based on the extent of clinical presentation and central cornea basal epithelial cell density (BCD). Methods: This is a retrospective observational case-control study of forty-eight eyes of 35 patients with LSCD and 9 eyes of 7 normal subjects were included. Confocal images of the central cornea were acquired. A clinical scoring system was created based on the extent of limbal and corneal surface involvement. LSCD was graded as mild, moderate, and severe stages based on the clinical scores. The degree of BCD reduction was given a score of 0 to 3. Results: Compared with BCD in control eyes, BCD decreased by 23.0%, 40.4%, and 69.5% in the mild, moderate and severe stages of LSCD classified by the clinical scoring system, respectively. The degree of BCD reduction was positively correlated with larger limbal and corneal surface involvement, and when the central visual axis was affected (all p≤0.0005). The mean CDVA LogMAR was 0.0±0.0 in control eyes, 0.2±0.5 in mild LSCD, 0.6±0.4 in moderate LSCD, and 1.6±1.1 in severe LSCD (p<0.0001). There was a significant correlation between a higher clinical score and CDVA LogMAR (rho = 0.82; p<0.0001) and a greater decrease of BCD (rho = −0.78; p<0.0001). Conclusion: A clinical scoring system was developed to assess the extent of clinical presentation of LSCD. A classification system to grade the severity of LSCD can be established by combining the BCD score with the clinical score.

Purpose To investigate the prevalence of dry eye disease (DED) and its associated risk factors among Thai university students. Methods A cross-sectional study using an electronic survey was conducted in two Rajabhat universities in Bangkok, Thailand. The woman’s health study questionnaire was used to determine students with DED. The prevalence of DED along with 95% confidence interval (CI) were calculated. Logistic regression model was used to identify the associated risk factors. Results A total of 4,111 university students joined and completed the survey questionnaires. Mean age was 18.8 ± 1.1 years with female predominance (2874 students, 69.91%). Clinically diagnosed DED was reported in 136 students (3.31%), while severe symptoms of eye dryness and irritation were reported in 227 students (5.52%). The prevalence of DED among Thai university students was 8.15% (95% CI 7.33% to 9.02%). History of contact lens use and high screen time (> 8 hours per day) were reported in 868 students (21.11%) and 2101 students (51.11%), respectively. Male gender, contact lens use and high screen time were significantly associated with higher risk of DED with the adjusted ORs (95% CI) of 1.39 (1.09, 1.77), 2.49 (1.96, 3.17), and 1.43 (1.14, 1.80), respectively. Conclusions DED is not rare among Thai university students. Contact lens use and high screen time are two significant modifiable risk factors of DED in our students. These findings can raise awareness of DED in youth population and provide valuable information for public health promotion in university students.

Purpose To assess the repeatability of anterior segment parameters and axial length (AL) using Pentacam AXL and Galilei G6 and the agreement between both devices. Materials and Methods Eighty-four eyes of 84 participants were measured prospectively with two devices. Outcome measurements included corneal curvatures, anterior chamber depth (ACD), AL, pupil size, and white-to-white distance (WTW). Intra-device repeatability was assessed using intraclass correlation coefficient (ICC), within-subject standard deviation (Sw), test–re-test repeatability (TRT=2.77 Sw), and coefficient of variation (CoV). Agreement between two devices was analyzed using Bland–Altman plots. Results For each device, the Sw of corneal curvatures, ACD, and AL were lower than 0.25 D, 0.04 mm, and 0.04 mm, respectively. The ICC was higher than 0.90 in all parameters measured by Pentacam AXL, whereas three parameters measured by Galilei G6 (steep meridian at anterior and posterior cornea, and pupil size) were lower than 0.90. Comparing to Galilei G6, Pentacam AXL led to significantly lower mean anterior cornea curvatures (Km) with the mean difference (95% level of agreement; LoA) of −0.12 D (−0.36, 0.12, P <0.001). For ACD, there was no significant difference between the two devices. Pentacam AXL led to significantly lower AL, pupil size, and WTW, with the mean differences (95% LoA) of −0.04 mm (−0.35, 0.27), −0.18 mm (−0.71, 0.35), and −0.35 mm (−0.61, −0.10), respectively. Conclusion We found good repeatability of corneal curvature, ACD, and AL in both devices. Most parameters obtained from Pentacam AXL were statistically significantly different from those obtained from Galilei G6, except for steep meridians and ACD.