Higher order aberrations and visual function in a young Asian population of high myopes.

Purpose: To examine the associations between higher order aberrations (HOAs), visual performance, demographics, and ocular characteristics in a young Asian population with high myopia. Methods: This was a retrospective review of military pre-enlistees conducted between March 2014 to September 2018. Visual acuity and contrast sensitivity were tested under photopic, mesopic and simulated night conditions. Ocular, corneal and internal HOAs were measured with a Hartmann-Shack wavefront aberrometer (KR-1W, Topcon Co., Tokyo, Japan). Results: 522 eyes of 263 consecutive subjects with severe high myopia (defined as spherical equivalent refraction [SER] ≤ -10.00D) in at least one eye, and high myopia (SER ≤ -6.00D) in the fellow eye, [mean (SD) SER -11.85 (2.03D)] were analysed. The mean (SD) age of subjects was 18.5 (1.6) years. Chinese eyes had significantly greater internal total HOA root-mean-square (RMS) compared to Malay eyes [mean difference (SD) 0.0246 (0.007) µm, p < 0.001). More negative SER was associated with greater ocular total HOA (p = 0.038), primary coma (p = 0.003) and tetrafoil (p = 0.025) RMS, as well as more positive ocular (p = 0.003) and internal primary spherical aberration (p = 0.009). Greater ocular total HOAs was associated with reduced visual acuity in simulated night conditions and low contrast, decreased contrast sensitivity under mesopic and simulated night conditions (all p < 0.05). Conclusions: Greater HOAs were associated with Chinese ethnicity and more negative SER in a young Asian population with high myopia. Greater HOAs were associated with poorer visual performance in low luminance and reduced contrast conditions.

A mixed method study on the impact of living with spinal muscular atrophy in Malaysia from patients' and caregivers' perspectives.

BACKGROUND: Spinal Muscular Atrophy (SMA) is a rare, recessively inherited neuromuscular disorder that causes progressive muscle weakness. There is a low degree of awareness about SMA amongst the public and healthcare providers, which may impact the perception of the disease and its proper management. To understand how this lack of awareness may have affected diagnosis, care and support for SMA patients and their caregivers, this study aims to investigate the impact of SMA on the lives and daily activities of SMA patients and their caregivers in Malaysia. METHODS: Nationwide recruitment was carried out via invitations coordinated by a local SMA advocacy organization. A mixed method cross-sectional study consisting of a self-administered questionnaire followed by in-depth interviews (IDIs) and focus group discussions (FGDs) was conducted. The interview sessions were audio-taped, and verbatim transcripts analyzed thematically. RESULTS: Participants reported feeling stressed, anxious and depressed. There were issues with delayed diagnosis, lack of information from healthcare professionals about the disease progression, and limited access to supportive services like physiotherapy. Participants expressed their concerns living with self-doubt and turmoil with having to modify their lifestyles, relationships with family and friends, and challenges with educational and career opportunities. Various themes of their hopes for the future touched on having access to treatment, clinical trials, holistic care for symptom management, as well as improving infrastructure for disability access. CONCLUSION: This study, to the best of our knowledge represents the first comprehensive study on SMA in South East Asia, highlights a plethora of issues and challenges experienced by persons with spinal muscular atrophy (PWSMA) and their caregivers in Malaysia, from the point of SMA diagnosis and throughout the management of care, in addition to the deep psychosocial impact of living with SMA. The significant findings of this study may contribute to a better understanding among stakeholders to make improvements in clinical practice, the education system, the work environment as well as holistic care support and society at large.

Correlation of myopia severity with visual performance.

PURPOSE: To describe visual performance in high myopia. METHODS: In this cross-sectional study, 148 emmetropes [spherical equivalent (SE) - 0.50 to + 1.00 D] and 564 high myopes [SE ≤ - 6.00 D] were categorised into three groups (Group 1: SE - 6.00 to > - 8.00 D; Group 2: SE - 8.00 to > - 10.00 D; and Group 3: SE ≤ - 10.00 D). Multivariate regression analyses adjusting for age and ethnicity examined the relationship between corrected distance visual acuity (CDVA) [photopic, mesopic and super vision test-night vision goggles (SVT-NVG)] and contrast sensitivity (CS)] (mesopic and SVT-NVG) with SE and axial length (AL). RESULTS: Mean age of subjects was 21.07 ± 1.17 years, and majority were Chinese (91.9%). Mean SE was 0.10 ± 0.23 D (emmetropes) and - 8.76 ± 2.04 D (high myopes), p < 0.001. Higher degrees of myopia were associated with reduced CDVA and CS, and increased AL (all p < 0.001). Among high myopes, Group 1 had the highest proportion of subjects with good CDVA (photopic ≤ 0.00 LogMAR, mesopic ≤ 0.00 LogMAR and NVG ≤ 0.10 LogMAR) and CS (mesopic ≥ 0.75 LogCS and NVG ≥ 0.35 LogCS) compared with Groups 2 and 3 (all p < 0.001). Among high myopes with good VA (photopic ≤ 0.00 LogMAR, mesopic ≤ 0.00 LogMAR and NVG ≤ 0.10 LogMAR), Group 1 also had the highest proportion of subjects who achieved mesopic ≥ 0.75 LogCS and NVG ≥ 0.35 LogCS (both p < 0.001). Multivariate analyses demonstrated that reduced VA and CS were associated with decreased SE and increased AL (all p < 0.001). CONCLUSIONS: High myopia is associated with reduced VA and reduced CS.

Refractive outcomes, corneal haze and endothelial cell loss after myopic photorefractive keratectomy in an Asian population: The Singapore Armed Forces' experience.

IMPORTANCE: This study reports outcomes of myopic photorefractive keratectomy (PRK) in a mainly ethnic Chinese population in Singapore. BACKGROUND: To assess the incidence and associations of corneal haze and endothelial cell count (ECC) loss up to 12 months after PRK. DESIGN: This was a retrospective case series conducted in a tertiary eye centre. PARTICIPANTS: A total of 158 patients (309 eyes) with a mean age of 22.1 ± 3.4 years were included. The majority was Chinese (97.4%) and male (97.4%). Mean preoperative spherical equivalent was -3.33 ± 1.15 D. METHODS: Eyes were categorized based on postoperative haze severity. A multivariate analysis adjusting for age and use of intraoperative mitomycin-C (MMC), preoperative sphere and cylinder was performed. MAIN OUTCOME MEASURES: Refractive outcomes and corneal haze 3 and 12 months after PRK were assessed. ECC measurements were obtained before PRK and at variable periods postoperatively. RESULTS: At 12 months, overall efficacy index was 0.98, and safety index was 1.09. Eight (2.5%) eyes underwent enhancement surgery. An analysis was performed on 295 eyes that did not undergo enhancement and had complete clinical data, which demonstrated a decrease in the incidence of haze from 38.2% at 3 months to 9.3% at 12 months. Higher myopia was associated with increased haze severity at 3 months (OR, 1.36; P = .005). Higher astigmatism was associated with increased haze severity at 3 (OR, 1.65; P = .018) and 12 months (OR, 2.32; P = .015). Intraoperative MMC was not associated with haze severity or ECC loss. CONCLUSIONS AND RELEVANCE: Myopia and astigmatism were associated with increased corneal haze severity. Intraoperative MMC did not accelerate ECC loss. Overall, PRK is effective, predictable and safe in Asian eyes.

Acoustically Driven Micromixing: Effect of Transducer Geometry.

The ability to drive efficient micromixing on a microfluidic platform is crucial for a wide range of lab-on-a-chip applications. Here, we investigate the ability of acoustic waves generated on different geometric surfaces (concave and convex) to enhance the micromixing efficiency in droplet acoustomicrofluidic systems, and, concomitantly, to reduce the power consumption in these devices for a given performance requirement. Quite counterintuitively, we observe that although the acoustic streaming velocity, which scaled inversely with the droplet size, tended to be generally lower (by approximately 45%) when the flow is generated by transducers with convex surfaces compared to those with concave surfaces, the mixing efficiency is disproportionately higher: compared to pure diffusional mixing in the absence of the acoustic forcing, the mixing efficiency due to the acoustically driven convection increased by up to 25% and 43% on these respective surfaces. As such, the mixing enhancement cannot simply be attributed to an increase in the convective flow arising from the acoustic forcing. Rather, we observe the mixing enhancement to be due to the stronger chaotic advection arising in the transducer with the convex surface due to its diverging acoustic field into the droplet.

Characterization of Choroidal Morphologic and Vascular Features in Young Men With High Myopia Using Spectral-Domain Optical Coherence Tomography.

PURPOSE: To describe detailed morphologic and vascular features of the choroid in eyes with high myopia. DESIGN: Cross-sectional study. METHODS: A total of 515 eyes of young men (mean age 21.59 ± 1.15 years) with high myopia (defined as -6.0 diopter [D] or worse, mean spherical equivalent -8.66 ± 2.00 D) and 88 controls with emmetropia in both eyes underwent choroidal imaging using spectral-domain optical coherence tomography with enhanced depth imaging (EDI-OCT). Raw OCT images were loaded on a custom-written application on MATLAB that enabled delineation for detailed morphologic and vascular analyses, including the distance of thickest point from the foveal center, choroidal thickness, choroidal volume, choroidal vascular and stromal areas within the macular (6 mm) and foveal (1.5 mm) regions, and choroidal vascularity, which was determined by dividing vascular area by total choroidal area. RESULTS: The choroid in high myopic eyes was thickest temporally compared to subfoveal location in emmetropic subjects (thickest point distance from fovea: -1.51 ± 1.42 mm vs -0.53 ± 1.06 mm, P < .001). In eyes with high myopia, after adjusting for age, choroidal vascular and stromal areas were significantly lower (vascular area: ß = -0.306, stromal area: ß = -0.377, both P < .001) than control eyes with emmetropia at the macular region. Compared to control eyes with emmetropia, choroidal vascularity was greater in eyes with high myopia (ß = 0.032, P < .001). Similar results were observed for the subfoveal region. CONCLUSION: Our study suggests that choroidal thinning in eyes with high myopia is associated with the reduction in both its stromal and vascular components.

Risk factors for early-onset corneal haze after photorefractive keratectomy in an Asian population: Outcomes from the Singapore Armed Forces Corneal Refractive Surgery Programme 2006 to 2013.

PURPOSE: To assess the incidence and risk factors for early corneal haze after myopic photorefractive keratectomy (PRK). SETTING: Tertiary eye center, Singapore. DESIGN: Retrospective case series. METHODS: The refractive results and corneal haze severity 3 months after PRK were analyzed. Eyes were categorized into 4 groups based on haze severity. Multivariate ordinal logistic regression analysis adjusting for age, ethnicity, sex, use of intraoperative mitomycin-C (MMC), preoperative sphere, and preoperative cylinder was performed. RESULTS: The study reviewed data from 177 patients (347 eyes) with a mean age of 22.6 years ± 4.1 (SD). The majority of the patients were Chinese (98.3%) and men (98.3%). The mean preoperative spherical equivalent (SE) was -3.34 ± 1.19 diopters (D). One hundred thirty-five eyes (38.9%) had PRK with MMC. Ten eyes (2.9%) had enhancement surgery. The overall efficacy index was 0.88 and the safety index was 1.07. At 3 months, 187 eyes (53.9%) had no haze, 76 eyes (21.9%) had a haze grade of more than 0 and less than 1, 76 eyes (21.9%) had a haze grade of 1 or more and less than 2, and 8 eyes (2.3%) had grade 2 haze. Higher degrees of myopia (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.13-1.63; P = .001) and astigmatism (OR, 1.56; 95% CI, 1.09-2.24; P = .014) were associated with increased severity of corneal haze, whereas older age (OR, 0.94; 95% CI, 0.88-0.99; P = .023) had a protective effect. CONCLUSION: Myopia and astigmatism were associated with increased severity of haze, and older age was protective against early corneal haze development after PRK in an Asian population. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.