Prevalence and risk factors of dry eye disease among University Students in Bangkok, Thailand.

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.

Contact Lens Use Patterns, Behavior and Knowledge Among University Students in Thailand.

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.

Comparison of Anterior Segment Parameters and Axial Length Using Two Scheimpflug Devices with Integrated Optical Biometers.

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.

Classification of Limbal Stem Cell Deficiency Using Clinical and Confocal Grading.

PURPOSE: To grade the severity of limbal stem cell deficiency (LSCD) based on the extent of clinical presentation and central corneal basal epithelial cell density (BCD). METHODS: This is a retrospective observational comparative study of 48 eyes of 35 patients with LSCD and 9 eyes of 7 normal subjects (controls). 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 controls, 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). Mean corrected distance visual acuity logarithm of the minimum angle of resolution 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 corrected distance visual acuity logarithm of the minimum angle of resolution (rho = 0.82; P < 0.0001) and a greater decrease in BCD (rho = -0.78; P < 0.0001). CONCLUSIONS: 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.

Characterization of the Corneal Subbasal Nerve Plexus in Limbal Stem Cell Deficiency.

PURPOSE: To quantify the changes in the subbasal nerve plexus in patients with limbal stem cell deficiency (LSCD) using in vivo laser scanning confocal microscopy. METHODS: In this retrospective cross-sectional comparative study, 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 were analyzed. Two independent observers evaluated the scans of the central cornea. Seventeen normal eyes of 13 subjects served as controls. Total subbasal nerve density (SND), density of long nerves (ie, 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 and 9.7 ± 10.9 nerves/mm, respectively, in all eyes with LSCD and 97.3 ± 29.9 and 35.3 ± 25.3 nerves/mm, 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.

Visual prognostic value of ocular electrophysiology tests in corneal transplantation.

OBJECTIVE: To determine visual prognostic value of electrophysiologic tests in unilateral-eye-disease patients who underwent corneal transplantation. MATERIAL AND METHOD: Retrospective charts of the patients who underwent unilateral optical penetrating keratoplasty at Siriraj Hospital from September 2003-June 2009 were reviewed. The amplitude of a-wave and b-wave in dark-adapted bright flash ERG and the amplitude of major positivity (P2) in flash VEP were recorded and compared with the good fellow eye. Area under receiver operating characteristic curve (AUC) was used to determine the best predictor of good visual prognosis. Positive predictive value (PPV) and negative predictive value (NPV) were used to determine the accuracy of the tests. RESULTS: Thirty-nine patients were included. The present study showed that a-wave amplitude was a good predictor (AUC = 0.83). For a-wave amplitude that was equal to or more than 80% and P2 amplitude that was equal to or more than 67%, PPV was 95.65%. CONCLUSION: The a-wave amplitude and P2 amplitude predict good visual outcome most accurately when changing less than 20% and 33%, respectively, compared to the normal fellow eye.