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.

Comparison of Ethnic-specific Databases in Heidelberg Retina Tomography-3 to Discriminate Between Early Glaucoma and Normal Chinese Eyes.

PURPOSE: To compare the diagnostic accuracy of the 3 race-specific normative databases in Heidelberg Retina Tomography (HRT)-3, in differentiating between early glaucomatous and healthy normal Chinese eyes. METHOD: 52 healthy volunteers and 25 glaucoma patients were recruited for this prospective cross-sectional study. All underwent standardized interviews, ophthalmic examination, perimetry and HRT optic disc imaging. Area under the curve (AUC) receiver operating characteristics, sensitivity and specificity were derived to assess the discriminating abilities of the 3 normative databases, for both Moorfields Regression Analysis (MRA) and Glaucoma Probability Score (GPS). RESULTS: A significantly higher percentage (65%) of patients were classified as "within normal limits" using the MRA-Indian database, as compared to the MRA-Caucasian and MRA-African-American databases. However, for GPS, this was observed using the African-American database. For MRA, the highest sensitivity was obtained with both Caucasian and African-American databases (68%), while the highest specificity was from the Indian database (94%). The AUC for discrimination between glaucomatous and normal eyes by MRA-Caucasian, MRA-African-American and MRA-Indian databases were 0.77 (95% CI, 0.67-0.88), 0.79 (0.69-0.89) and 0.73 (0.63-0.84) respectively. For GPS, the highest sensitivity was obtained using either Caucasian or Indian databases (68%). The highest specificity was seen with the African-American database (98%). The AUC for GPS-Caucasian, GPS-African-American and GPS-Indian databases were 0.76 (95% CI, 0.66-0.87), 0.77 (0.67-0.87) and 0.76 (0.66-0.87) respectively. CONCLUSION: Comparison of the 3 ethnic databases did not reveal significant differences to differentiate early glaucomatous from normal Chinese eyes.

Effect of head tilt on repeatability of optic nerve head parameters using cirrus spectral-domain optical coherence tomography.

AIM: To assess the repeatability of measuring optic nerve head (ONH) parameters using the Cirrus optical coherence tomography (OCT), as well as to assess the effect of head tilt on these measurements. METHODS: Thirty healthy participants with no evidence of glaucoma were recruited for the study. Visual acuity, intraocular pressure, standard automated perimetry and ocular examination were performed for each participant. One eye was then randomly selected and scanned undilated with the Cirrus OCT in 3 positions (neutral, 30° right tilt and 30° left tilt). RESULTS: Data collected from 29 eyes were used for analysis. One patient was omitted due to poor scan quality. The repeatability of the ONH parameters was analyzed using analysis of variance, coefficient of variation (COV) and intraclass correlation coefficient (ICC). Analysis of variance showed no statistically significant difference between 3 scans in a single position. There was good agreement between measurements (ICC 0.919-0.996, COV 1.94%-5.48%). Even with the presence of head tilt, repeated scans in the 3 positions showed good agreement as well (ICC 0.888-0.996, COV 2.04%-5.39%). CONCLUSION: Serial measurements of ONH parameters using the Cirrus OCT are found to have good repeatability. The ONH parameters with Cirrus OCT also maintain good repeatability despite head tilt.

Pattern of Visual Field Loss in Primary Angle-Closure Glaucoma Across Different Severity Levels.

PURPOSE: To investigate the patterns of visual field (VF) defects in primary angle-closure glaucoma (PACG) across different severity levels and to assess hemifield differences within each severity level. DESIGN: Cross-sectional study. PARTICIPANTS: Three hundred four patients diagnosed with PACG were recruited from glaucoma clinics at a Singapore hospital. METHODS: Point-wise total deviation values were recorded from the static automated perimetry (Swedish interactive threshold algorithm standard program 24-2; Humphrey model 750 [Carl Zeiss Meditec, Dublin, CA]) printouts. Patients were excluded if they had unreliable VFs (fixation losses >33% and false-positive responses >15%), had undergone only 10-2 VF testing, had VF defects not typical of glaucoma, or had undergone cataract extraction. Mild, moderate, and severe VF loss were defined by a mean deviation of -6.00 dB or more, -6.01 to -12.00 dB, and -12.01 dB or less, respectively. Each hemifield was divided into regions according to glaucoma hemifield test sectors. The average mean deviation (MD) of each region was obtained using total deviation values. MAIN OUTCOME MEASURES: Between- and within-hemifield differences of the regions across the severity levels. RESULTS: After excluding ineligible cases, 249 patients with PACG were included in the analysis. Mean age of the patients was 65.7±8.6 years, with a 1:1 gender ratio. The number of patients who had mild, moderate, and severe VFs was 72 (28.9%), 78 (31.3%), and 99 (39.8%), respectively. For between-hemifield comparisons, all regions in the superior hemifield had worse MDs compared with their counterparts in the inferior hemifield across the severity spectrum. Likewise, for within-hemifield comparisons, MDs of the regions gradually worsened with increasing distance from the fixation point. CONCLUSIONS: In this group of clinic-based PACG patients, the superior hemifield was found to be affected more severely than the inferior hemifield, and the differences between them increased with worsening disease severity. The damage was consistently more pronounced in the nasal area.

Effect of Head Tilt and Ocular Compensatory Mechanisms on Retinal Nerve Fiber Layer Measurements by Cirrus Spectral Domain and Spectralis Optical Coherence Tomography in Normal Subjects.

PURPOSE: To determine the effect of head tilt and ocular compensatory mechanisms on retinal nerve fiber layer (RNFL) thickness measurements using the Cirrus and Spectralis spectral-domain optical coherence tomography (OCT) in healthy eyes. Our secondary objective was to assess the visual influence on ocular compensatory mechanisms during head tilt. MATERIALS AND METHODS: This is a prospective, observational study. A single randomly selected eye was scanned undilated in 3 positions (baseline, right, and left tilt) using both machines. In addition, patching was also done for the contralateral eye during head tilt and RNFL measurements repeated. The paired t test was used to analyze effect on RNFL thickness. One-way repeated-measures analysis of variance was used to compare differences in RNFL measurements. RESULTS: In Cirrus OCT RNFL analysis, ipsilateral head tilt resulted in superior thinning and temporal thickening, whereas contralateral head tilt resulted in inferior thinning, nasal thickening, as well as temporal thickening (all P<0.05). Head tilt did not cause any significant change in RNFL thickness with Spectralis OCT (P>0.05). Patching the contralateral eye also did not alter Cirrus RNFL measurement errors due to head tilt. CONCLUSIONS: Head tilt can affect the measurement of the RNFL thickness in Cirrus OCT, and ocular compensatory mechanisms were not sufficient to prevent this. In contrast, Spectralis OCT RNFL thickness measurements were not affected by head tilt. Patching the contralateral eye during head tilt in Cirrus OCT also did not affect RNFL variability. The visual influence on ocular compensatory mechanisms during head tilt appears insignificant.

Syphilitic uveitis in a Singaporean population.

PURPOSE: To report the presentations of syphilitic uveitides in Singapore. METHODS: Retrospective noncomparative observational case series of 18 eyes from 12 patients with ocular syphilis between 2004 and 2009. RESULTS: Patients were mainly male (91.7%). Median age was 49.5 (24-84) years. Initial visual acuity varied from 6/6 to counting fingers (CF) and was ≥6/12 in 7 eyes (38.8%). Blurring of vision (n = 11, 61.1%) was the most common presenting complaint. Anterior uveitis and panuveitis were both most common (n = 6, 33.3%). Treponemal and nontreponemal serologies were positive in 12 (100.0%) and 10 (83.3%) patients, respectively. Patients were treated systematically with penicillin therapy by infectious disease physicians. CONCLUSIONS: Ocular syphilis is seeing a worldwide resurgence. Although anterior uveitis and panuveitis were most common in this study, there was a large spectrum of ocular manifestations. Syphilitic uveitides can potentially cause severe loss of vision but are effectively treated by an appropriate regimen of penicillin.