Age- and Gender-Related Characteristics of Corneal Refractive Parameters in a Large Cohort Study

Trans Palpebral Intraocular Pressure Measurement by Diaton Tonometer and Central Corneal Thickness in Eyes before and after Transepithelial Photorefractive Keratectomy of Saudi Patients

PURPOSE

The influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurement by Diaton is debatable. We present a correlation of CCT to transpalpebral IOP (tpIOP) and its determinants in patients undergoing transepithelial photorefractive keratectomy (TPRK) in Saudi Arabia.

METHODS

In this cross-sectional study held in 2022, the IOP of patients undergoing TPRK was measured by Diaton tonometer. The CCT was measured before and 1 week after refractive surgery. The correlation coefficient of CCT and IOP and its Pearson P value were estimated. The effects of gender, type of refractive error (RE), and corneal epithelial thickness (CET) on the correlation of IOP to CCT were reviewed.

RESULTS

We studied 202 eyes in 101 patients (Male: Female, 47:53; age 25.7 ± 5.8 years). The tpIOP was 15.1 ± 2.8 mmHg before, 15.9 ± 2.8 mmHg 1 week after, and 15.7 ± 4.1 mmHg 1 month after TPRK. The CCT was significantly correlated with tpIOP before surgery (Pearson correlation 0.168, P = 0.017) and after tPRK (Pearson correlation 0.246, P < 0.001). Gender (P = 0.96), CET (P = 0.43), and type of RE (P = 0.99) were not significant determinants of correlation between CCT and tpIOP before TPRK. The correlation of tpIOP and CCT was not affected by gender (P = 0.07), CET (P = 0.39), and type of RE (P = 0.13).

CONCLUSION

CCT should be considered before interpreting tpIOP measured by with Diaton. Diaton could be a useful tool to monitor IOP changes in young patients undergoing refractive surgery.

Distribution of pediatric keratoconus by different age and gender groups

PURPOSE

To evaluate the distribution of pediatric keratoconus patients and the disease severity based on different age and gender groups in China.

MATERIALS AND METHODS

A total of 446 keratoconus eyes in 266 pediatric patients from January 2019 to January 2022 were included in the cross-sectional study. The clinical findings and severity of keratoconus were recorded and Kruskal-Wallis test, chi-squared test, and Cochran-Mantel-Haenszel (CMH) test were used to compare the parameters between different gender and age groups.

RESULTS

The male/female ratio was 353/93 (3.8:1), and the median age was 16 years (range: 6-17 years). Male patients were statistically younger than female patients (P = 0.041). The male/female ratio decreased with age (P for trend = 0.011). The distribution of the topographic keratoconus classification (TKC) stage was significantly different between gender and age groups (all P < 0.05). Male patients had a higher ratio of advanced keratoconus eyes (TKC ≥ 3) than female patients (P < 0.001), and CMH analysis indicated that being a male was a risk factor for advanced keratoconus after controlling for age (odds ratio: 2.581, P < 0.001).

CONCLUSION

Male keratoconus patients were younger, with a higher ratio of advanced keratoconus than female patients in the Chinese pediatric patients evaluated. Multicenter studies with larger sample sizes are necessary in the future.

Effect of Sunshine Duration on Myopia in Primary School Students from Northern and Southern China

Background

To assess the current myopia prevalence rate and evaluate the effect of sunshine duration on myopia among primary school students in the north and south of China.

Methods

This prospective cross-sectional study pooled data from 9171 primary school students (grades from 1 to 6) from four cities in the north and south of China. National Geomatics Center of China (NGCC) and China Meteorological Administration provided data about altitude, latitude, longitude, average annual temperature, and average annual sunshine duration. Non-cycloplegic refraction was recorded, and prevalence rates in primary school students and factors associated with myopia were analyzed. Univariate and multivariate logistic regression models were used to determine the independent association of risk factors of myopia.

Results

The overall myopia prevalence was 28.0%, from 7.5% to 50.6% for first and sixth grades, respectively. Low, moderate and high myopia significantly increased with school grades from 7.30% to 35.0%, 0.3% to 13.60% and 0.00% to 1.9%, respectively. Multiple regression analysis revealed that longer average cumulative daylight hours were connected to lower myopia prevalence in primary school students (OR, 0.721; 95% CI, [0.593–0.877]; P=0.001), whereas girls and higher grade was independently associated with higher myopia prevalence (girls: β=0.189; OR, 1.208; 95% CI, [1.052–1.387]; P=0.007; higher grade: β=0.502; OR, 1.652; 95% CI, [1.580–1.726]; P<0.001).

Conclusion

This study demonstrated that myopia was highly prevalent in southern Chinese cities over northern ones, linked to shorter light exposure, higher education level, and female gender. Such findings reinforced the beneficial impact of daylight exposure with a protective role against myopia development.

PRK Enhancement for Residual Refractive Error After Primary PRK: A Retrospective Study

Introduction

The efficacy and safety of photorefractive keratectomy (PRK) has been well documented, but outcomes of PRK enhancement following PRK remain understudied. This study aimed to evaluate the safety, efficacy, and predictability of PRK enhancement in patients with residual refractive error after primary PRK and compare these results to prior studies as well as Food and Drug Administration (FDA) safety and efficacy clinical endpoints.

Methods

This non-randomized, retrospective chart analysis included eyes with a history of PRK that underwent PRK enhancement at a single center. Post-enhancement data were documented at 3-month and 1-year visits. Patient characteristics between the study group and a control group who underwent primary PRK only were compared. Safety and efficacy measures included change in uncorrected distance visual acuity (UDVA), change in corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), amount of induced astigmatism, and presence of serious adverse events.

Results

A total of 188 eyes from 141 patients were included. When compared to the control group, women underwent PRK enhancement at a higher rate than men (P = 0.004). The group undergoing PRK enhancement had a higher sphere (P = 0.013) and spherical equivalent (P = 0.004) than the control group at the time of primary PRK. MRSE was reduced to − 0.97 ± 0.72 D (− 2.25 to + 2.13 D) from pre-enhancement values of − 0.98 ± 0.66 D (− 2.75 to + 1.75 D) and stable over 12-month visits with 86% and 98% of eyes within ± 0.50 D and ± 1.00 D of target, respectively. UDVA of 20/20 or better was achieved in 75% of eyes. The UDVA of 75% of eyes remained the same or improved by 1 or more Snellen lines compared with pre-enhancement CDVA.

Conclusion

Our results demonstrate that, when compared with previous studies, modern PRK enhancement after PRK has improved visual acuity and refractive outcomes. Though PRK enhancement is not an FDA approved procedure, we show that it meets or exceeds the FDA criteria for the correction of refractive error.