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.

Physiological response to the odorant TMT in fully fed and calorically restricted laboratory mice.

2,3,5-trimethyl-3-thiazoline (TMT) is a chemical compound that is extracted from red fox urine and can be used to artificially simulate the presence of a predator. The purpose of this study was to test the hypothesis that TMT would block entry into torpor in the calorically restricted C57Bl/6 mouse. We first demonstrated that TMT induced fear in the mouse. Exposure to TMT induced an acute freeze response (67.2 ± 6.7% of time), as compared to 6.7 ± 1.7% when exposed to water. Further, exposure to TMT for 30 min led to elevated circulating corticosterone levels, 377 ± 33 ng/ml, as compared to 29 ± 4 ng/ml when exposed to water. When mice were exposed to TMT during the dark or light phase, body temperature (Tb) dropped by 1.7 ± 0.9 °C and 0.7 ± 1.1 °C, respectively, over the first 110 min after exposure. To determine whether TMT influences daily torpor, mice were calorically restricted and exposed to either water or TMT. Mice were exposed 30 min before the start of torpor, determined by the bout of the previous day. Exposure to TMT significantly (p < 0.01) blunted the fall in the minimum Tb from 28.8 ± 0.3 °C (water) to 30.1 ± 0.6 °C (TMT) and significantly (p < 0.05) decreased the amount of time Tb was under 32 °C, from 431 ± 48 min (water) to 292 ± 78 min (TMT). These results establish that mice perceived the scent of TMT as a physiologically stressful stimulus and that Tb response is modestly blunted in the presence of that stressor. Our experiment highlights the intricate interplay between predation risk and energy conservation.

Highlights from the 2019 International Myopia Summit on 'controversies in myopia'.

Myopia is an emerging public health issue with potentially significant economic and social impact, especially in East Asia. However, many uncertainties about myopia and its clinical management remain. The International Myopia Summit workgroup was convened by the Singapore Eye Research Institute, the WHO Regional Office for the Western Pacific and the International Agency for the Prevention of Blindness in 2019. The aim of this workgroup was to summarise available evidence, identify gaps or unmet needs and provide consensus on future directions for clinical research in myopia. In this review, among the many 'controversies in myopia' discussed, we highlight three main areas of consensus. First, development of interventions for the prevention of axial elongation and pathologic myopia is needed, which may require a multifaceted approach targeting the Bruch's membrane, choroid and/or sclera. Second, clinical myopia management requires co-operation between optometrists and ophthalmologists to provide patients with holistic care and a tailored approach that balances risks and benefits of treatment by using optical and pharmacological interventions. Third, current diagnostic technologies to detect myopic complications may be improved through collaboration between clinicians, researchers and industry. There is an unmet need to develop new imaging modalities for both structural and functional analyses and to establish normative databases for myopic eyes. In conclusion, the workgroup's call to action advocated for a paradigm shift towards a collaborative approach in the holistic clinical management of myopia.

The heat is on: A device that reduces cold stress-induced tachycardia in laboratory mice.

Mouse vivaria are typically maintained at an ambient temperature (Ta) of 20-26 °C which is comfortable for human researchers. However, as this Ta is well below the mouse thermoneutral zone (TNZ) of 30-32 °C, typical vivarium temperatures result in cold stress for mice. Recently, a cage has been developed that provides variable cage floor heating, allowing mice to behaviorally regulate body temperature through thermotaxis. A hand warmer provides supplemental heat, elevating cage floor surface temperature for 13 + hours up to 30 °C. This provides a heated surface for the entirety of the light phase. Here, we test the ability of these local heat sources to remove physiological signs of cold stress in mice housed at room temperature by analyzing heart rate (HR), activity, and body temperature in three experimental conditions: 23 °C, 23 °C + heated surface, or 30 °C. The location of C57Bl/6 J mice within the cage was recorded using an infrared camera. In the presence of supplemental heat at a Ta of 23 °C, mice resided atop of the area of the heated surface 85 ±â€¯3% of the 12-h light phase, as compared to 7 ±â€¯2% in the absence of supplemental heat. Further, addition of supplemental heat lowered light phase HR and activity to that seen at a Ta of 30 °C. These results indicate that provision of a local heat source is successful in reducing cold-induced tachycardia in mice housed at typical vivarium temperatures without increasing the ambient temperature of the entire laboratory and subjecting researchers to heat stress.

Eighteen-year prospective audit of LASIK outcomes for myopia in 53 731 eyes.

BACKGROUND: To assess the outcomes of laser-assisted in situ keratomileusis (LASIK) performed for the treatment of myopia in terms of safety, efficacy and predictability in an 18-year clinical audit. METHOD: In this single-centre, prospective, non-randomised study, preoperative and postoperative refractions, uncorrected (UCVA), best-corrected Snellen visual acuity (BCVA) and complications of all eyes undergoing myopic LASIK were recorded. Safety, efficacy, refractive predictability, treatment trends, retreatment rates and complication rates were evaluated. RESULTS: Between 1998 and 2015, 53 731 eyes of 27312 patients underwent myopic LASIK. Patients' median age was 31.6 years (mean, 32.6±7.3 years); there were 9703 males (35.5%). Patients were predominantly ethnic Chinese (87.4%). Mean follow-up time was 78±75.6 days (median, 86 days). Overall efficacy index was 0.91 with >99% of eyes achieving UCVA of ≥20/40 and >70% achieving 20/20 since 2010. 95.43% of eyes had no loss of vision postoperatively and 4.2% and 0.37% lost 1 and ≥2 lines BCVA, respectively. From 2010 the safety index has been >1.05. More than 94.0% of eyes achieved within ±1.0 D of target refraction and at least 70% achieved within ±0.50 D of target from 2010 onwards. Retreatment rate was 2.55% and after retreatment 98.4% of eyes achieved ≥20/40 UCVA and 63.5% achieved ≥20/20 UCVA. The overall complication rate is 0.98%, and since 2010, the annual complication rate has been <0.8%. CONCLUSIONS: Myopic LASIK performed in Asian eyes is safe and effective with high refractive predictability in a comprehensive LASIK programme with appropriate clinical audit.

Analysis of cases and accuracy of 3 risk scoring systems in predicting ectasia after laser in situ keratomileusis.

PURPOSE: To identify risk factors for ectasia after laser in situ keratomileusis (LASIK) by comparing the accuracy of the Ectasia Risk Score System (ERSS), Screening Corneal Objective Risk of Ectasia (SCORE) Analyzer, and percentage of tissue altered (PTA) in predicting the occurrence of ectasia. SETTING: Multiple centers in 8 countries. DESIGN: Retrospective case series. METHODS: Previously unpublished post-LASIK ectasia cases were analyzed. Consecutive patients who had LASIK performed at least 5 years previously with no resultant ectasia were used as controls. Axial maps from preoperative Orbscan IIz topographies were analyzed in a masked fashion, and examination files tested with the SCORE Analyzer. The PTA values and ERSS scores were generated using available preoperative and perioperative data. Only eyes with subjectively identified normal preoperative topography were tested with the PTA. Threshold values for the SCORE, ERSS, and PTA were more than or equal to 0, 4, and 40, respectively. RESULTS: Ectasia occurred in 31 eyes (22 patients); 79 eyes (44 patients) were used as controls. In all eyes, the sensitivity and specificity for predicting ectasia, respectively, were 67.7% and 79.7% for the ERSS and 64.5% and 100% for the SCORE. In eyes with normal topography (ectasia group, 12 eyes; controls, 64 eyes), the PTA yielded sensitivity of 33.3% and specificity of 85.9%. The area under the receiver operating characteristic curve was highest for SCORE (0.911) followed by the ERSS (0.844) and PTA (0.557). CONCLUSIONS: The SCORE was most predictive of ectasia, achieving the best specificity; the ERSS had the best sensitivity. Further studies are required to validate the PTA as a screening metric for ectasia.

Conventional Versus Accelerated Collagen Cross-Linking for Keratoconus: A Comparison of Visual, Refractive, Topographic and Biomechanical Outcomes.

OBJECTIVE: The aim was to compare the visual, refractive, topographic and biomechanical outcomes in patients with progressive keratoconus treated with either conventional or accelerated crosslinking at one year follow up. METHODS: It is a prospective, non-randomised interventional study of 76 patients who underwent conventional (CXL; 3mW/cm2 for 30 minutes) or accelerated cross linking (KXL; 30mW/cm2 for 4 minutes) for progressive keratoconus. Baseline and postoperative visual acuity, manifest refraction, corneal topography, pachymetry, endothelial cell density and biomechanical parameters of corneal hysteresis and corneal resistance factor were evaluated and compared. RESULTS: The 2 groups were comparable in terms of uncorrected and best corrected visual acuity and spherical equivalent. Both groups showed no significant increase in K1, K2 and Kmean from baseline at 12 months. There was also no difference between the CXL and KXL group for postoperative corneal topography as well as central and minimal pachymetry up to 12 months. There was a significant increase in both corneal hysteresis (0.62mm Hg, P=0.04) and corneal resistance factor (0.91mm Hg, P=0.003) in the KXL group at 12 months but not in the CXL group. There was no significant endothelial cell loss throughout follow up in both the groups. CONCLUSION: We have established comparability of the 2 protocols in stabilizing the progression of keratoconus. Our findings also suggested an added biomechanical advantage of accelerated crosslinking at 1 year follow up.

Validation of an Objective Scoring System for Forme Fruste Keratoconus Detection and Post-LASIK Ectasia Risk Assessment in Asian Eyes.

PURPOSE: To investigate the efficacy of the SCORE Analyzer (Bausch+Lomb TechnoLas, Germany) in detecting forme fruste keratoconus (FFKC) in Asian eyes and validate its usefulness as a risk assessment system for post-laser in situ keratomileusis (LASIK) keratectasia. METHODS: We retrospectively evaluated corneal topographies with the Orbscan IIz system and independently tested them with the SCORE Analyzer through masked investigators. Eyes were classified into 2 groups: (1) The FFKC group included clinically and topographically normal eyes with definite keratoconus in the contralateral eye. (2) The control group included normal preoperative topographies of patients with LASIK performed at least 4 years before with no resultant keratectasia. The main outcome measures were accuracy indicators: sensitivity, specificity, positive, and negative predictive values. Parameters in the calculation of the SCORE including irregularity at 3 mm, thinnest pachymetry, the difference between central and thinnest pachymetry (CP - TP), vertical decentration of the thinnest point, maximum posterior elevation, and anterior elevation of the thinnest point were compared in both groups. RESULTS: We analyzed 128 Orbscans of 128 Asian patients. There were 24 FFKC eyes and 104 control eyes. SCORE was negative in 7 eyes (false negative) in the FFKC group and was positive in 2 eyes in the control group (false positive). The sensitivity was 70.8%, specificity 98.1%, positive predictive value 89.5%, and negative predictive value 93.6%. Irregularity at 3 mm, thinnest pachymetry, CP - TP, thinnest point decentration, maximum posterior elevation, and anterior elevation of the thinnest point were significantly different in both groups. CONCLUSIONS: The SCORE Analyzer algorithm, developed and validated in eyes of white subjects, was found to be valid and consistent in Asian eyes, showing good sensitivity and specificity in FFKC detection, and to be useful in objectively identifying cases at risk of post-LASIK keratectasia.

Postoperative ocular higher-order aberrations and contrast sensitivity: femtosecond lenticule extraction versus pseudo small-incision lenticule extraction.

PURPOSE: To evaluate and compare changes in contrast sensitivity and ocular higher-order aberrations (HOAs) after femtosecond lenticule extraction (FLEx) and pseudo small-incision lenticule extraction (SMILE). SETTING: Singapore National Eye Centre, Singapore. DESIGN: Retrospective case series. METHOD: Patients had femtosecond lenticule extraction (Group 1) or pseudo small-incision lenticule extraction (Group 2) between March 2010 and December 2011. The main outcome measures were manifest refraction, HOAs, and contrast sensitivity 1, 3, 6, and 12 months postoperatively. RESULTS: Fifty-two consecutive patients (102 eyes) were recruited, 21 patients (42 eyes) in Group 1 and the 31 patients (60 eyes) in Group 2. The uncorrected and corrected distance visual acuities were significantly better in Group 2 than in Group 1 at 12 months (P = .032). There was no significant increase in 3rd- or 4th-order aberrations at 1 year and no significant difference between the 2 groups preoperatively or postoperatively. At 1 year, there was a significant increase in mesopic contrast sensitivity in Group 2 at 1.5 cycles per degree (cpd) (P = .008) that was not found in Group 1, and photopic contrast sensitivity at 6.0 cpd was higher in Group 2 (P = .027). CONCLUSIONS: These results indicate that refractive lenticule extraction is safe and effective with no significant induction of HOAs or deterioration in contrast sensitivity at 1 year. Induction of HOAs was not significantly different between both variants of refractive lenticule extraction. However, there was significant improvement in photopic contrast sensitivity after pseudo small-incision lenticule extraction, which persisted through 1 year. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Incidence and management of suction loss in refractive lenticule extraction.

PURPOSE: To describe the incidence, management, and outcomes of suction loss in refractive lenticule extraction (ReLEx). SETTING: Tertiary eye hospital. DESIGN: Retrospective case series. METHOD: All patients who experienced suction loss during refractive lenticule extraction from March 9, 2010, to August 5, 2013, were evaluated preoperatively, including slitlamp biomicroscopy, fundoscopy, corneal topography, ultrasound pachymetry, manifest and cycloplegic refractions, and measurement of uncorrected (UDVA) and corrected (CDVA) distance visual acuities. Patients were followed at predetermined timepoints. At each follow-up visit, the UDVA and CDVA were measured and slitlamp biomicroscopy was performed. Manifest refraction was measured 1 and 3 months postoperatively. RESULTS: During the study period, 340 refractive lenticule extractions were performed. The overall cumulative incidence of suction loss was 3.2%. The incidence of suction loss was 4.3% (2/46) for femtosecond lenticule extraction, 4.4% (8/183) for small-incision lenticule extraction, and 0.9% (1/109) for pseudo small-incision lenticule extraction. Of the 11 eyes in which suction loss occurred, 8 (72.7%) had a UDVA of 20/30 or better and 9 (81.8%) had a spherical equivalent within ± 0.5 diopter of emmetropia at 3 months. Suction loss occurred in 4 eyes during the posterior lenticule cut, in 5 eyes during the anterior lenticule cut, and in 2 eyes during the lamellar flap cut. In 9 of these (81.8%), suction was reapplied and the procedure was completed without further complications. CONCLUSIONS: The incidence of suction loss during refractive lenticule extraction was relatively low. Good visual outcomes were achieved with appropriate management.

Refractive lenticule extraction: transition and comparison of 3 surgical techniques.

PURPOSE: To describe the transition and outcomes of 3 refractive lenticule extraction (ReLEx) techniques: femtosecond lenticule extraction (FLEx), small-incision lenticule extraction (SMILE), and pseudo small-incision lenticule extraction. SETTING: Singapore National Eye Center, Singapore. DESIGN: Prospective comparative case series. METHODS: Refractive lenticule extraction was performed between March 1, 2010, and November 1, 2012, using the Visumax 500 kHz femtosecond laser system. The main outcome measures were the refractive efficacy, predictability, and safety over 12 months. RESULTS: The study enrolled 88 eyes. All 3 refractive lenticule extraction techniques yielded good refractive outcomes and stability over 12 months. Three months postoperatively, the mean overall efficacy index of refractive lenticule extraction was 0.89±0.22 (SD), with 95.5% of eyes attaining an uncorrected distance visual acuity (UDVA) of better than 20/40 and 60.2% of better than 20/20. Of all eyes, 95.5% were within ±1.00 diopter (D) and 78.4% within ±0.50 D of the attempted correction. The mean overall safety index was 1.06±0.17. At 3 months, all small-incision lenticule extraction eyes and 96.7% of pseudo small-incision lenticule extraction eyes had a UDVA of 20/40 or better, while femtosecond lenticule extraction eyes had a lower efficacy index (87.0%). However, efficacy was comparable in all 3 groups by 12 months (mean 0.87±0.04 [standard error of the mean]; P=1.00). CONCLUSION: The efficacy, safety, and predictability profiles of the 3 refractive lenticule extraction techniques were good over a 12-month follow-up. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Prevalence and viral load of oncogenic human papillomavirus (HPV) in pterygia in multi-ethnic patients in the Malay Peninsula.

PURPOSE: The aim of the study was to determine the prevalence of human papillomavirus (HPV) in primary and recurrent pterygia samples collected from different ethnic groups in the equatorial Malay Peninsula. METHODS: DNA was extracted from 45 specimens of freshly obtained primary and recurrent pterygia from patients and from 11 normal conjunctival swabs from volunteers with no ocular surface lesion as control. The presence of HPV DNA was detected by nested PCR. PCR-positive samples were subjected to DNA sequencing to determine the HPV genotypes. Real-time PCR with HPV16 and HPV18 type-specific TaqMan probes was employed to determine the viral DNA copy number. RESULTS: Of 45 pterygia samples with acceptable DNA quality, 29 (64.4%) were positive for HPV DNA, whereas all the normal conjunctiva swabs were HPV negative. Type 18 was the most prevalent (41.4% of positive samples) genotype followed by type 16 (27.6%). There was one case each of the less common HPV58 and HPV59. Seven of the samples harboured mixed infections of both HPV16 and HPV18. All the four known recurrent pterygia samples were HPV-positive, whereas the sole early-stage pterygium sample in the study was HPV-negative. There was no significant association between HPV-positive status with gender or age. A high proportion of patients from the Indian ethnic group (five of six) were HPV-positive, whereas the Malay patients were found to have higher HPV positivity than the Chinese. The viral load of HPV18 samples ranged between 2 × 10(2) and 3 × 10(4) copies per µg, whereas the viral load of HPV16 specimen was 4 × 10(1) to 10(2) copies per µg. CONCLUSION: This report describes for the first time the quantitative measurement of HPV viral DNA for pterygium samples. The high prevalence of oncogenic HPVs in our samples suggests a possible role for HPV in the pathogenesis of pterygia. Moreover, the relatively low HPV viral load is concordant with the premalignant nature of this ocular condition.

Comparative analysis of two femtosecond LASIK platforms using iTRAQ quantitative proteomics.

PURPOSE: New femtosecond laser platforms may reduce ocular surface interference and LASIK-associated dry eye. This study investigated tear protein profiles in subjects who underwent LASIK using two femtosecond lasers to assess differences in protein expression. METHODS: This was a randomized interventional clinical trial involving 22 patients who underwent femtosecond laser refractive surgery with a contralateral paired eye design. Corneal flaps of 22 subjects were created by either Visumax or Intralase laser. Tear samples were collected preoperatively, and at 1 week and 3 months postoperatively using Schirmer's strips. Tear protein ratios were calculated relative to preoperative protein levels at baseline. The main outcome measures were the levels of a panel of dry eye protein markers analyzed using isobaric tagging for relative and absolute quantitation (iTRAQ) mass spectrometry. RESULTS: A total of 824 unique proteins were quantifiable. Tear protein ratios were differentially regulated between the eyes treated with different lasers. The secretoglobulins Lipophilin A (1.80-fold) and Lipophilin C (1.77) were significantly upregulated (P < 0.05) at 1 week postoperatively in Visumax but not in Intralase-treated eyes. At 1 week, orosomucoid1 was upregulated (1.78) in Intralase but not Visumax-treated eyes. In the same eyes, lysozyme, cathepsin B, and lipo-oxygenase were downregulated at 0.44-, 0.64-, and 0.64-folds, respectively. Transglutaminase-2 was downregulated in both groups of eyes. CONCLUSIONS: Different laser platforms induce distinct biological responses in the cornea and ocular surface, which manifests as different levels of tear proteins. This study has implications for surgical technology and modulation of wound healing responses. (ClinicalTrials.gov number, NCT01252654.).

Patient and surgeon experience during laser in situ keratomileusis using 2 femtosecond laser systems.

PURPOSE: To describe the subjective experience of patients and surgeons during laser in situ keratomileusis (LASIK) using the Intralase 60 kHz or the Visumax 500 kHz femtosecond laser. SETTING: Singapore National Eye Centre, Singapore. DESIGN: Prospective randomized clinical study. METHODS: In myopic patients, LASIK was performed with the corneal flap created using the 60 kHz laser in 1 eye and the 500 kHz laser in the contralateral eye. Postoperatively, patients completed a standardized validated questionnaire about their subjective intraoperative experiences (eg, light perception, pain, fear). Surgeons reported their intraoperative experiences and preferences. RESULTS: Loss of light perception occurred in 50.0% of 60 kHz laser cases and 0% of 500 kHz laser cases during docking and in 63.0% and 0% of cases, respectively, during laser flap creation (P < .0001). The mean pain score with the 60 kHz laser was significantly higher during docking (P < .0001) but not during laser flap cutting (P = .006). Subconjunctival hemorrhage occurred in 67.4% of eyes with the 60 kHz laser and in 2.2% of eyes with the 500 kHz laser (P < .0001). The 500 kHz laser was preferred by 78.3% of patients, while 21.7% preferred the 60 kHz laser (P < .0001). The surgeons preferred the 60 kHz laser in 50.0% of cases and the 500 kHz laser in 8.7% (P < .0001); 41.3% had no preference. CONCLUSIONS: Patients preferred surgery with the 500 kHz laser with no loss of light perception, less pain, less fear, and less subconjunctival hemorrhage. Surgeons preferred the 60 kHz laser.

Visual outcomes comparison of 2 femtosecond laser platforms for laser in situ keratomileusis.

PURPOSE: To compare the efficacy, predictability, and safety outcomes of 2 femtosecond laser platforms for flap creation during laser in situ keratomileusis (LASIK) for myopia and myopic astigmatism. SETTING: Singapore National Eye Centre, Singapore. DESIGN: Retrospective case review. METHODS: In this single-center multisurgeon study, patients had LASIK with flaps created using a Visumax 500 kHz or Intralase 60 kHz femtosecond laser system. Ablation was performed with the Wavelight Allegretto Eye-Q 400 Hz excimer laser in all patients. Preoperative and 3-month postoperative manifest refraction, attempted treatment spherical equivalent (SE), visual acuity, and complications were compared. RESULTS: The 500 kHz femtosecond laser group comprised 381 patients (381 eyes) and the 60 kHz femtosecond laser group, 362 patients (362 eyes). Three months postoperatively, the uncorrected distance visual acuity was 20/40 or better in 99.1% of eyes in the 60 kHz laser group and 99.4% of eyes in the 500 kHz laser group (P=.678). Regarding predictability, 98.6% of eyes and 97.4% of eyes, respectively, were within ± 1.0 diopter of the attempted SE correction postoperatively (P=.228). The safety index was similar in the 60 kHz laser group and the 500 kHz laser group (mean 1.06 ± 0.16 [SD] versus 1.05 ± 0.14) (P=.321). CONCLUSION: The safety, predictability, and efficacy profiles of the 500 kHz femtosecond platform for LASIK were excellent and comparable to those of the 60 kHz platform.

Comparison of efficacy and safety of laser in situ keratomileusis using 2 femtosecond laser platforms in contralateral eyes.

PURPOSE: To compare the efficacy, predictability, and refractive outcomes of laser in situ keratomileusis (LASIK) using 2 femtosecond platforms for flap creation. SETTING: Multisurgeon single center. DESIGN: Clinical trial. METHODS: Bilateral femtosecond LASIK was performed using the Wavelight Allegretto Eye-Q 400 Hz excimer laser system. The Visumax femtosecond platform (Group 1) was used to create the LASIK flap in 1 eye, while the Intralase femtosecond platform (Group 2) was used to create the LASIK flap in the contralateral eye. The preoperative, 1-month, and 3-month postoperative visual acuities, refraction, and contrast sensitivity in the 2 groups were compared. RESULTS: The study enrolled 45 patients. Three months after femtosecond LASIK, 79.5% of eyes in Group 1 and 82.1% in Group 2 achieved an uncorrected distance visual acuity of 20/20 (P=.808). The mean efficacy index was 0.97 in Group 1 and 0.98 in Group 2 at 3 months (P=.735); 89.7% of eyes in Group 1 and 84.6% of eyes in Group 2 were within ± 0.50 diopter of emmetropia at 3 months (P=.498). No eye in either group lost more than 2 lines of corrected distance visual acuity. The mean safety index at 3 months was 1.11 in Group 1 and 1.10 in Group 2 (P=.570). CONCLUSION: The results of LASIK with both femtosecond lasers were similar, and both platforms produced efficacious and predictable LASIK outcomes. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Comparison of corneal sensitivity, tear function and corneal staining following laser in situ keratomileusis with two femtosecond laser platforms.

PURPOSE: To evaluate longitudinal changes in corneal sensitivity, tear function, and corneal staining in patients who underwent laser in situ keratomileusis (LASIK) using two different femtosecond lasers. METHODS: In a prospective, randomized clinical trial, contralateral eyes of 45 patients underwent flap creation by either VisuMax or IntraLase™ femtosecond laser. Corneal sensitivity, tear break up time (TBUT), Schirmer's test, and corneal fluorescein staining were assessed preoperatively and at 1 week, 1 month, and 3 months postoperatively. RESULTS: There were no statistical differences in any clinical outcome measure between the two femtosecond lasers (P > 0.05), although there was a trend towards slightly lower reductions for corneal sensitivity and TBUT in VisuMax-operated eyes. Overall, corneal sensitivity was significantly reduced at 1 week (P < 0.05), 1 month (P < 0 .001), and 3 months (P < 0.001) postoperatively. A significantly greater reduction of corneal sensitivity was noted in eyes with a myopic spherical equivalent of -6.00 diopters (D) to -11.25 D as compared with eyes that had a relatively lower level of myopia of less than -6.00 D (P < 0.001). TBUT and Schirmer's test values were significantly diminished at 1 week postoperatively (P < 0.04). Overall, corneal staining was significantly increased at 1 week postoperatively (P < 0.001). The level of myopia did not significantly affect postoperative changes in TBUT, Schirmer's test values, or corneal staining (P > 0.05). CONCLUSION: This study showed that changes in corneal sensitivity, tear function, and corneal staining were statistically similar in LASIK using VisuMax and IntraLase femtosecond lasers for flap creation. However, the trend towards faster recovery of corneal sensitivity and TBUT observed in VisuMax-operated eyes may be attributable to improved technical specifications.

Refractive lenticule extraction flap and stromal bed morphology assessment with anterior segment optical coherence tomography.

PURPOSE: To evaluate the flap and stromal bed after refractive lenticule extraction using optical coherence tomography (OCT). SETTING: Singapore National Eye Centre, Singapore. DESIGN: Longitudinal case series. METHODS: Horizontal scans (RTVue) were taken preoperatively and after refractive lenticule extraction. Two procedures were performed: femtosecond lenticule extraction and small-incision femtosecond lenticule extraction. Flap and bed thicknesses were measured at the center (0.0 mm) and 1.5 mm and 3.0 mm to either side. RESULTS: At 1 week, the mean flap at 0.0 mm was borderline thicker (P=.056) and at +3.0 mm significantly thicker after femtosecond lenticule extraction than after small-incision femtosecond lenticule extraction (P=.003). The mean bed at 0.0 mm was thinner after femtosecond lenticule extraction (P=.03). The flap at -3.0 mm showed thinning between 1 week and 3 months after small-incision femtosecond lenticule extraction (P=.018). The flap at +3.0 mm thinned between 1 week and 1 month after femtosecond lenticule extraction (P=.009). After femtosecond lenticule extraction, there were increases in bed (P=.027) and total corneal (P=.013) thicknesses at 0.0 mm between 1 week and 3 months, remaining stable thereafter (3 months: P=.842 and P=.508, respectively). The mean spherical equivalent decreased and the uncorrected acuity improved after both procedures (P<.001), with stabilization of both variables at 3 months. CONCLUSION: A significant difference in stromal bed thickness between femtosecond lenticule extraction and small-incision femtosecond lenticule extraction was detectable by AS-OCT 1 week postoperatively.

Steroid-induced ocular hypertension in Asian children with severe vernal keratoconjunctivitis.

BACKGROUND: We describe clinical characteristics and risk factors for corticosteroid response in children with severe vernal keratoconjunctivitis (VKC). DESIGN: Retrospective, noncontrolled, comparative case series. PARTICIPANTS: Patients from three tertiary centers in Singapore. METHODS: We reviewed patients with severe VKC (clinical grade > 2) who were on topical steroid therapy, with a minimum follow-up period of 1 year post-presentation. Logistic regression was used to determine risk factors for corticosteroid response. MAIN OUTCOME MEASURE: Corticosteroid response was defined as intraocular pressure (IOP) >21 mmHg (three consecutive readings), or a rise of more than 16 mmHg from baseline, after commencement of steroid therapy in the absence of other possible causes of raised IOP. RESULTS: Forty-one of 145 (28.3%) patients developed a corticosteroid response, of which eight (5.5%) progressed to glaucoma. The overall mean age of onset of VKC was 9.9 ± 4.4 years. Longer duration of corticosteroid use (OR, 5.06; 95% CI: 1.04-25.56; P = 0.45) and topical dexamethasone 0.01% (OR, 2.25; 95% CI: 1.99-5.08; P = 0.40) were associated with corticosteroid response. Mixed type of VKC (OR, 9.76; 95% CI: 3.55-26.77; P < 0.001), the presence of limbal neovascularization of ≥ three quadrants (OR, 6.33; 95% CI: 2.36-16.97; P < 0.001), and corneal involvement (OR, 3.51; 95% CI: 1.31-9.41; P = 0.012) were significant clinical risk factors after adjusting for potential confounders such as age, sex, ethnicity, duration, and type of corticosteroid used. CONCLUSION: Children on long-term oral corticosteroids with severe, mixed-type VKC and corneal involvement are more likely to develop corticosteroid response, and may require early treatment to prevent progression to glaucoma.

Severe vernal keratoconjunctivitis requiring trabeculectomy with mitomycin C for corticosteroid-induced glaucoma.

BACKGROUND: To describe clinical features of severe vernal keratoconjunctivitis with steroid response in Asian children and risk factors for glaucoma filtration surgery. DESIGN: Retrospective non-controlled, comparative case series. PARTICIPANTS: Patients with severe vernal keratoconjunctivitis seen at a single centre over 6 years. METHODS: Clinical features, symptoms and treatment modalities were recorded for patients (i) diagnosed with severe VKC (clinical grade ≥ 3); (ii) had >2 recordings of increased intraocular pressures of >21 mmHg; (iii) and a minimum follow-up period of 1 year post-presentation. MAIN OUTCOME MEASURE: Corticosteroid-induced glaucoma requiring trabeculectomy with mitomycin-C. RESULTS: Six patients (eight eyes) of 36 patients required trabeculectomy/mitomycin-C. All were male. Mean age of disease onset was 9.3 ± 4.5 years for a mean duration of 6.08 ± 3.5 years. Mean intraocular pressures increase from baseline was 29.0 ± 8.2 mmHg and all required >2 anti-glaucoma medications. The main risk factor for trabeculectomy was a greater increase in intraocular pressures from baseline (odds ratio 1.3; 95% confidence interval, 1.0-1.5; P = 0.011), which was independent of potential confounders such as type and duration of corticosteroid use. Comparing eyes pre- and post-trabeculectomy, all improved in clinical severity of vernal keratoconjunctivitis (mean clinical grade improvement 2.1; 95% confidence interval, 1.3-3.0; P < 0.001) and reduced dependence on topical corticosteroids for mean duration of 22.5 ± 15.3 months. CONCLUSION: In our study, patients with a 'greater steroid response', that is, higher increase in intraocular pressures from baseline are associated with a 30% higher risk toftrabeculectomy.