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.

Assessment and Management of Dry Eye Disease and Meibomian Gland Dysfunction: Providing a Singapore Framework.

ABSTRACT: The purpose of this article is to provide a framework for general ophthalmologists in Singapore to manage dry eye. This framework considers the evidence in the literature as well as recommendations from expert panels such as the Tear Film & Ocular Surface Society Dry Eye Workshop II and the Asia Cornea Society Workgroup.This article covers the assessment of patient medical history and ask triage questions to identify local and systemic causes of dry eye disease (DED), excluding other possible causes, as well as the risk factors for DED and ocular surface inflammation. Evaluation of clinical signs to establish the diagnosis of DED and differentiation from other causes of irritable, red eyes are described. Tests for understanding the underlying disease processes and severity of DED are also presented.Management of dry eye should involve patient education and engagement. Information about the natural history and chronic nature of DED should be provided to improve long-term management of the disease and enhance compliance. Aggravating factors should be removed or lessened.We provide a guide to determine the most appropriate treatment (or combination of treatments) based on the severity and cause(s) of the disease, as well as the patient's needs and preferences. The aim of the management is to relieve ocular discomfort and prevent worsening of symptoms and signs, as well as to optimize visual function and minimize structural ocular damage. We also discuss the systematic follow-up and assessment of treatment response, as well as monitoring side effects of treatment, bearing in mind continuous support and reassurance to patients.

Accuracy of intraocular lens formulas using total keratometry in eyes with previous myopic laser refractive surgery.

OBJECTIVES: This comparative study aimed to determine if total keratometry (TK) from IOLMaster 700 could be applied to conventional formulas to perform IOL power calculation in eyes with previous myopic laser refractive surgery, and to evaluate their accuracy with known post-laser refractive surgery formulas. METHODS: Sixty-four eyes of 49 patients with previous myopic laser refractive surgery were evaluated 1 month after cataract surgery. A comparison of the prediction error was made between no clinical history post-laser refractive surgery formulas (Barrett True-K, Haigis-L, Shammas-PL) and conventional formulas (EVO, Haigis, Hoffer Q, Holladay I, and SRK/T) using TK values obtained with the optical biometer IOLMaster 700 (Carl Zeiss Meditec), as well as Barrett True-K with TK. RESULTS: The mean prediction error was statistically different from zero for Barrett True-K, Barrett True-K with TK, Haigis-L, Shammas-PL, and Holladay I with TK. The mean absolute error (MAE) was 0.424, 0.671, 0.638, 0.439, 0.408, 0.424, 0.479, 0.647, and 0.524, and median absolute error (MedAE) was 0.388, 0.586, 0.605, 0.298, 0.294, 0.324, 0.333, 0.438, and 0.377 for Barrett True-K, Haigis-L, Shammas-PL, Barrett True-K TK, EVO with TK, Haigis with TK, Hoffer Q with TK, Holladay I with TK, and SRK/T with TK, respectively. EVO TK followed by Barrett True-K TK and Haigis TK achieved the highest percentages of patients with absolute prediction error within 0.50 and 1.00 D (68.75%, 92.19%, and 64.06%, 92.19%, respectively) CONCLUSIONS: Formulas combined with TK achieve similar or better results compared to existing no-history post-myopic laser refractive surgery formulas.

One-year follow-up of femtosecond laser-assisted penetrating keratoplasty.

BACKGROUND: The purpose of this report is to describe the initial outcomes of femtosecond laser-assisted penetrating keratoplasty. METHODS: This retrospective surgical case series consisted of 10 eyes from 10 patients undergoing penetrating keratoplasty at a tertiary center. Femtosecond laser was used to perform a zig-square incision on the donor cornea with matched dimensions on the recipient cornea. Outcomes measured included: unaided visual acuity and best spectacle-corrected visual acuity preoperatively and at one, 3, 6, and 12 months postoperatively; manifest refractive and topographic astigmatism at 3, 6, and 12 months postoperatively; and endothelial cell density loss, calculated at the end of the one-year follow-up period. RESULTS: At one-year follow-up, there was an improvement in unaided visual acuity from a mean preoperative logMAR of 1.67 to 0.44, and best spectacle-corrected visual acuity from a mean preoperative logMAR of 1.33 to 0.13. By postoperative month 3, mean manifest refractive and topographic astigmatism was 2.31 ± 1.41 D and 2.59 ± 1.57 D, respectively. The mean reduction in endothelial cell density was 20.7% after one year of follow-up. CONCLUSION: Femtosecond laser-assisted penetrating keratoplasty provided a good visual outcome and early visual rehabilitation due to precise graft-host alignment and reduced astigmatism in the early postoperative months.

Heat profiling of phacoemulsification tip using a thermal scanning camera.

An experimental study to measure the heat profile of the phacoemulsification (phaco) tip using standard continuous phaco and hyperpulse phaco with and without waveform power modulation in the Millennium Microsurgical System with Custom Control Software (CCS). The phaco tip was imaged in air using a thermal camera. The highest temperature was measured 15 s after application of phaco power. Continuous, hyperpulse and waveform power modulations of the Millennium Microsurgical System were used with different power settings (20, 50 and 100 %) and duty cycles (40, 60 and 90 %), with the irrigation turned on and off. Using continuous phaco with the irrigation on, the phaco tip temperature remains <28.0 °C. With irrigation off, the temperature is higher compared to irrigation on but still remains <45.0 °C. Comparing the temperatures for all three power modulations when irrigation is on, at each phaco power and duty cycle setting, the temperature of the phaco tip is highest with continuous phaco, followed by hyperpulse with rise time 1, then hyperpulse with rise time 2. When irrigation is off, the highest temperatures are recorded using the hyperpulse with rise time 2, followed by continuous phaco, then hyperpulse with rise time 1. Hyperpulse and waveform modulations reduce heat generation compared to the continuous mode when irrigation is turned on. Lower duty cycles and lower ultrasound power produce less heat at the phaco tip.

Analgesic effect of supplemental intracameral lidocaine during phacoemulsification under topical anaesthesia: a randomised controlled trial.

AIMS: To determine the analgesic effect of supplemental intracameral lidocaine 1% during phacoemulsification under topical anaesthesia, and to assess the risk factors associated with pain. METHODS: In a double-masked, randomised, clinical trial, 506 patients undergoing phacoemulsification under topical anaesthesia were randomised to receive a supplemental intracameral injection of either 0.5 cc of 1% lidocaine (277 patients, 54.7%) or balanced salt solution (BSS) (229 patients, 45.3%). Patients were interviewed by a trained interviewer using a standardised questionnaire. The main outcome measure was intraoperative pain, scored on a visual analogue scale of 0-10. Logistic regression was performed to assess ORs. RESULTS: 125 of 277 patients (45.1%) experienced pain in the lidocaine group, compared with 123 of 229 patients (53.7%) in the BSS group. The proportion of patients who experienced pain was significantly lower in the intracameral lidocaine group compared with the BSS group (multivariate OR 0.68, 95% CI 0.47 to 0.97; p=0.034). The median pain score (range) was 0.0 for intracameral lidocaine group compared with 1.0 for BSS group (p=0.039). Pain was more common in females (54.3% vs 43.6%; OR 1.56), non-Chinese (62.3% vs 46.9%; OR 2.13) and those who had previous cataract surgery to the fellow eye (55.3% vs 44.7%; OR 1.61). CONCLUSION: The use of 0.5 cc of 1% intracameral lidocaine during phacoemulsification under topical anaesthesia significantly reduces pain experienced by patients. Risk factors for pain include females, non-Chinese and previous cataract surgery.

Acanthamoeba keratitis associated with contact lens wear in Singapore.

PURPOSE: To describe an outbreak of Acanthamoeba keratitis (AK) cases among contact lens wearers. DESIGN: Retrospective cohort study. METHODS: Patients with AK were included. Relevant demographic and clinical data were obtained from case records, and patients were interviewed using a standardized questionnaire. Contact lens practices, including type of contact lens and solution used, were noted. In addition, clinical features at presentation, management, and clinical outcomes were recorded. RESULTS: Forty-two patients (affecting 43 eyes) treated between 2000 and 2007 were included. Diagnosis was made by microbiologic culture in 35 cases and by microbiologic and histologic analysis in 2 cases, whereas the remainder were diagnosed based on clinical features and response to treatment. There was a gradual increase in cases since 2005, with a sharp increase in 2007, when 8 local patients were treated. Of 30 patients where contact lens solution data were available, 18 reported using a Complete brand Multipurpose solution (Advanced Medical Optics, Santa Ana, California, USA) before the infection. Among resident cases treated since February 2006, 7 (63%) of 11 patients used a Complete brand solution. Suboptimal hygiene practices were found in all patients interviewed. Fifteen patients required corneal grafting, with 11 undergoing therapeutic deep lamellar keratoplasty (DLK), 2 undergoing optical penetrating keratoplasty (PK), 1 undergoing optical DLK, and 1 undergoing therapeutic PK. The remainder were treated successfully medically with combination antiamebic therapy. The average duration of therapy was 116.2 days (range, 15 to 283 days). Of patients with radial keratoneuritis with or without epithelial disease, 83.3% achieved final vision of 20/40 or better, whereas this was achieved in 41.7% of those with ring infiltrate. Twenty-five percent of patients with ring infiltrate had final visual acuity of counting fingers or worse, whereas no patient with keratoneuritis and epithelial disease had final vision worse than counting fingers. CONCLUSIONS: There was an increase in the number of contact lens users with AK seen in the major eye departments of Singapore. Most of our patients also reported using a Complete brand Multipurpose solution before infection, and this parallels a similar outbreak in the United States. Increasing severity of infection was associated with worse visual outcome.

Efficacy of measuring visual performance of LASIK patients under photopic and mesopic conditions.

INTRODUCTION: The aim of the study was to compare the visual performance of LASIK eyes measured using high-contrast logMAR letter charts under bright (photopic) and dim (mesopic) conditions. MATERIALS AND METHODS: A total of 46 subjects (35 +/- 8 years of age) undergoing LASIK procedures were recruited for the study. The best spectacle-corrected visual acuity (BSCVA) of each subject was measured using the high-contrast ETDRS logMAR chart under photopic and mesopic conditions at 3 visits: preoperative (Pre), 1 month postoperative (Post1) and 3 months postoperative (Post3). The differences in logMAR scores for the right eyes only were analysed for the Pre-Post1 (n = 46), Pre-Post3 (n = 18) and Post1-Post3 (n = 16) comparisons. RESULTS: The logMAR scores of subjects were worse at the 1-month postoperative visit than preoperatively, and improvement in visual performance was seen at the 3-month postoperative visit. These changes in visual performance became more evident under mesopic conditions. The means and standard errors of the differences in logMAR scores for the Pre-Post3 (0.097 +/- 0.020) were slightly larger than those of the Pre-Post1 (-0.067 +/- 0.019) and Post1-Post3 (0.031 +/- 0.012) comparisons. Under mesopic conditions, the visual performance of the subjects was statistically significant for the 3 comparisons, but not under photopic conditions. CONCLUSION: High-contrast logMAR chart performed under mesopic conditions has the potential to replace visual acuity measured under photopic conditions in providing more reliable representation of postoperative visual outcomes of LASIK eyes. Eye doctors should consider performing this vision test routinely to gauge the success of LASIK surgery.

Surgically-induced corneal changes following macular translocation with punctate retinotomies and chorioscleral infolding (limited macular translocation).

INTRODUCTION: To report the sequential changes in corneal topography and astigmatism following limited macular translocation. CLINICAL PICTURE AND TREATMENT: A 45-year-old-man who underwent limited macular translocation for idiopathic subfoveal choroidal neovascularisation in the right eye was evaluated by corneal topography and manifest refraction preoperatively and serially for 1 year postoperatively. OUTCOME: An increase in astigmatism with corneal steepening along meridians corresponding to the area of chorioscleral infolding was observed and this persisted for 1 year after surgery. Vector-analysed astigmatic change showed significant surgically induced astigmatism of 2.18 dioptres (D) X 52.9 degrees, 2.17 D X 57.8 degrees and 2.56 D X 59.1 degrees at 2, 5 and 12 months after surgery respectively. CONCLUSION: Surgically induced corneal changes are evident after limited macular translocation and may remain up to 1 year after surgery.

An outbreak of Fusarium keratitis associated with contact lens wear in Singapore.

CONTEXT: Fungal keratitis is a potentially blinding condition that is rarely seen with contact lens wear. OBJECTIVE: To describe a nationwide outbreak of fungal keratitis caused by Fusarium species among contact lens wearers in Singapore. DESIGN, SETTING, AND PATIENTS: Nationwide, hospital-based case series. All cases of fungal keratitis among contact lens wearers in all ophthalmology departments in Singapore were reviewed along with the charts of all contact lens wearers with culture-proven fungal keratitis from March 2005 through May 2006. A standardized telephone interview was conducted to obtain additional clinical information. MAIN OUTCOME MEASURE: Diagnosis of Fusarium keratitis associated with contact lens wear. RESULTS: During the study period, 66 patients (68 affected eyes) were diagnosed with Fusarium keratitis associated with contact lens wear; the estimated annual national incidence is 2.35 cases per 10,000 contact lens wearers (95% confidence interval, 0.62-7.22). Patients ranged in age from 13 to 44 years (mean [SD], 27.1 [8.4] years), of which 32 (48.5%) were men. The vast majority (65 patients; 98.5%) wore soft, disposable contact lenses; 62 patients (93.9%) reported using 1 brand of contact lens cleaning solution (ReNu, Bausch & Lomb, Rochester, NY), including 42 patients (63.6%) who recalled using ReNu with MoistureLoc. Most patients (81.8%) reported poor contact lens hygiene practices, including overnight use of daily wear contact lenses (19.7%), and use of contact lenses past the replacement date (43.9%). The final best-corrected visual acuity ranged from 20/20 to 20/80. Five patients (5 eyes; 7.4%) required emergency therapeutic or tectonic corneal transplantation. CONCLUSIONS: A new and evolving epidemic of Fusarium keratitis associated with contact lens wear was found in Singapore. Physicians and eye care practitioners worldwide need to be aware of the likelihood of similar outbreaks emerging among contact lens wearers.