Anterior chamber dimensions and posterior corneal arc length in Malay eyes: an anterior segment optical coherence tomography study.

PURPOSE: We provided normative data of corneal and anterior segment dimensions, and a novel parameter, posterior corneal arc length (PCAL), in an adult Malay population. METHODS: The current analysis is a substudy of the Singapore Malay Eye Study (SiMES), a population-based, cross-sectional study of urban Malay adults aged 40 to 80. Subjects underwent ophthalmic and systemic examination, including imaging with anterior segment optical coherence tomography (AS-OCT). Ocular parameters subsequently were measured with the Zhongshan Assessment Program (ZAP), and included anterior chamber depth (ACD), central corneal thickness (CCT), anterior and posterior corneal curvature (ACC and PCC, respectively), and PCAL, which is a novel parameter defined as the arc-distance of the posterior corneal border between the scleral spurs. Age- and sex-adjusted analyses, and multivariate analyses were performed to determine correlations of PCAL with other ocular and systemic components. RESULTS: We studied 237 subjects, among whom the mean age was 56.6 ± 10.4 years and 50.2% were women. Ocular parameters (mean ± SD) included central ACD 2.78 ± 0.34 mm, CCT 550.23 ± 37.12 mm, ACC 7.43 ± 0.37 mm, PCC 6.75 ± 0.37 mm, and PCAL 13.95 ± 0.51 mm. There was moderate correlation between PCAL and ACD (r = 0.476, P < 0.001), but poor correlation with PCC (r = 0.243, P < 0.001), ACC (r = 0.251, P < 0.001), and systemic parameters, like age, body mass index (BMI), blood pressure, blood glucose levels, hemoglobin A1c (HbA1c), and refractive parameters. Multivariate analysis showed a significant association between PCAL and ACD (P < 0.001), PCC (P < 0.001), and height (P < 0.05). CONCLUSIONS: Our study, to our knowledge, provides the largest baseline anterior segment parameters in an adult Asian Malay population. PCAL correlated moderately with ACD. These data are applicable clinically for assessment and surgical management of patients requiring anterior segment or corneal surgery.

Matched comparison of rotational stability of 1-piece acrylic and plate-haptic silicone toric intraocular lenses in Asian eyes.

PURPOSE: To evaluate and compare the postoperative rotational stability of a 1-piece acrylic toric intraocular lens (IOL) (Acrysof) and a plate-haptic silicone toric IOL (Staar) in Asian eyes. SETTING: Singapore National Eye Centre, Singapore. DESIGN: Prospective randomized control trial. METHODS: Eyes of Chinese patients having cataract surgery were randomized to receive the acrylic toric IOL or the silicone toric IOL. Postoperatively, patients returned at 1 day, 1 week, and 1 and 3 months. The eyes were dilated and slitlamp retroillumination photography of the toric IOL was performed to assess rotational stability. RESULTS: The acrylic IOL was implanted in 24 eyes and the silicone IOL in 26 eyes. The mean age of the patients was 68.2 years (range 42 to 82 years). The mean IOL rotation from baseline to 3 months postoperatively was 4.23 ± 4.28 degrees in the acrylic IOL group and 9.42 ± 7.80 degrees in the silicone IOL group; the difference was statistically significant (P=.01). Of the acrylic IOLs, 73% were rotated less than 5 degrees at 3 months; none was rotated more than 15 degrees at 3 months. The silicone toric IOLs showed greater rotational movement, with 37% being rotated less than 5 degrees and 21% being rotated more than 15 degrees. CONCLUSION: The acrylic toric IOL had better rotational stability than the silicone toric IOL.

Hemi-automated lamellar keratoplasty (HALK).

AIM: To describe a hybrid technique for anterior lamellar keratoplasty in corneas with topographical irregularities that circumvents the limitations of the microkeratome, namely reproduction of surface irregularities in the lamellar cut when creating the recipient flap. METHOD: Hemi-automated lamellar keratoplasty, a procedure that combines manual recipient bed lamellar dissection with automated donor preparation using a microkeratome, was performed on 14 eyes of 14 patients with heterogeneous causes of anterior stromal scarring. RESULTS: There was an overall improvement in uncorrected visual acuity (UCVA) in 78.6% (11/14) eyes and in best-corrected visual acuity (BCVA) in 78.6% (11/14) eyes at a mean of 9 months postoperatively. Mean preoperative and postoperative logMAR UCVAs were 1.31 ± 0.74 and 0.83 ± 0.46 (p=0.04), respectively. Mean preoperative and postoperative logMAR BCVAs were 0.72 ± 0.58 and 0.38 ± 0.23 (p=0.05). Mean preoperative and postoperative manifest refractive spherical equivalents were -0.76 ± 3.61 D and -0.52 ± 3.44 D (p=0.872). There was no difference in preoperative and postoperative sphere and cylinder (p=0.871 and 0.965, respectively). In a subset of six eyes with longer follow-up >12 months, the UCVA and BCVA show continuing improvement. All grafts remained clear at the final appointment. CONCLUSIONS: Hemi-automated lamellar keratoplasty is an effective and safe surgical procedure in the treatment of corneas with irregular topographic profiles with varying depths of anterior stromal scarring. It combines the benefits of smooth microkeratome lamellar dissection of the donor with customised lenticule thickness and diameter together with a manual lamellar dissection technique for the recipient providing encouraging visual outcomes that show continuing improvement with time.

Reproducibility of cornea measurements in anterior segment OCT images of normal eyes and eyes with bullous keratopathy analyzed with the Zhongshan Assessment Program.

PURPOSE: To determine the interobserver and intraobserver measurement reproducibility of cornea parameters of both normal eyes and eyes with bullous keratopathy (BK) obtained with the Zhongshan Assessment Program (ZAP) on anterior segment optical coherence tomography (AS-OCT) images. METHODS: A comparative study was carried out on 24 healthy volunteers and 25 subjects with BK. AS-OCT images were independently analyzed by two examiners. Parameters examined: anterior chamber depth (ACD), central corneal thickness (CCT), posterior corneal curvature (PCC), and posterior corneal arc length (PCAL). Interobserver and intraobserver reproducibility of these parameters was calculated in terms of limits of agreement (mean of differences ± 1.96SD of differences). RESULTS: In the normal group, both horizontal and vertical ACD were successfully measured in 23 of 24 (96%) images. The mean bias for two measurements by two different observers ranged from 0.003 to 0.117 mm for ACD, PCC, and PCAL measurements and from 0.013 to 2.25 µm for CCT measurements, and there were no differences between the two observers (P > 0.05). Mean bias for two measurements by the same grader ranged from 0.005 to 0.327 mm for ACD, PCC, and PCAL measurements and 1.46 to 2.53 µm for CCT measurements. There was no difference between the two observations (P > 0.05). Similar results were found in the BK group. CONCLUSIONS: There was high inter- and intraobserver reproducibility for normal and pathologic corneas using the ZAP software. The ZAP software may serve as a new investigatory tool for accurately evaluating the anterior segment and corneal parameters for corneal procedures.

Correcting post-keratoplasty anisometropia with the implantable collamer phakic intraocular lens.

BACKGROUND: We evaluate the Visian Implantable Collamer Lens (Staar, Monrovia, CA, USA) phakic intraocular lens for treating post-keratoplasty anisometropia. METHODS: Case series of three eyes (2 phakic and 1 pseudophakic). RESULTS: The mean age was 47.3 years (range 30-73 years), with a minimum of 3-month follow up. The mean preoperative spherical equivalent was -8.75 ± 5.17 D (-4.00 to -14.25 D) improving to -0.29 ± 1.21 D postoperatively (range 0.75 to -1.625 D). Mean logMAR uncorrected visual acuity improved from 1.66 ± 0.60 (6/240) preoperatively to 0.41 ± 0.52 (6/15(2) ). Mean logMAR best spectacle-corrected visual acuity improved from 0.32 ± 0.15 (6/12) preoperatively to 0.10 ± 0.11 (6/7.5). Anisometropia improved from a difference of 6.37 ± 2.59 D preoperatively to 2.09 ± 1.37 D postoperatively, and there were no complications. CONCLUSION: Our technique for this clinical indication shows that the Visian Implantable Collamer Lens is a safe and effective alternative for treating post-keratoplasty anisometropia.

Biometry of the cornea and anterior chamber in chinese eyes: an anterior segment optical coherence tomography study.

PURPOSE. To investigate the normative data of corneal and anterior segment biometric parameters and their associations in Chinese adults, for use in preoperative assessment for corneal and anterior segment surgery. METHODS. This cross-sectional, population-based study included 750 subjects aged > or =50 years. The subjects underwent an ophthalmic examination including imaging with anterior segment optical coherence tomography (AS-OCT). Dimensions were subsequently measured with the Zhongshan Assessment Program (ZAP). Also measured was posterior corneal arc length (PCAL), a novel parameter defined as the arc distance between scleral spurs on the posterior border of the cornea. Correlations with age, sex, height, weight, body mass index (BMI), refractive sphere and cylinder, and intraocular pressure were also measured. RESULTS. The subjects' mean age was 63.3 +/- 7.9 years and 349 (46.5%) were men. Corneal parameters (mean +/- SD) included PCAL (12.924 +/- 0.544 mm), anterior chamber depth (ACD; 2.684 +/- 0.309 mm), central corneal thickness (562.39 +/- 31.85 microm), anterior chamber curvature (7.35 +/- 0.37 mm), and posterior corneal curvature (6.65 +/- 0.34 mm). A moderate correlation was observed between PCAL and ACD (R = 0.55, P < 0.001) and a poor correlation between PCAL and age, height, weight, and BMI. Multivariate analysis showed a significant association between PCAL and ACD, ACC, PCC, and cylinder (P < 0.05). CONCLUSIONS. In this Chinese population, PCAL was found to correlate moderately with ACD. The data may be useful for corneal and anterior segment procedures such as Descemet's stripping automated endothelial keratoplasty (DSAEK).

A 10-year prospective audit of LASIK outcomes for myopia in 37,932 eyes at a single institution in Asia.

PURPOSE: This study evaluates the efficacy, predictability and safety of LASIK surgery as a treatment for myopia performed as part of a large-scale, prospective clinical audit spanning 10 years in an Asian study population and to evaluate the outcomes and trends. DESIGN: Prospective, nonrandomized, single-center, multisurgeon study. PARTICIPANTS: We included 37,932 eyes of 19,753 patients that underwent myopic LASIK at the Singapore National Eye Centre between 1998 and 2007. METHODS: All eyes underwent LASIK as a treatment for myopia. Pre- and postoperative refractions, uncorrected visual acuity (UCVA), and best-corrected visual acuity (BCVA) were documented. MAIN OUTCOMES MEASURES: Safety, efficacy, refractive predictability, treatment trends, retreatment rates, and complications for mild, moderate, and high myopia according to spherical equivalence (SE) of less than -5.00 diopters (D), -5.00 D or more to less than -10.0 D, and -10.00 D or more, respectively. RESULTS: Patients' median age was 32 years (mean, 33.0+/-7.9 years); there were 6832 males (34.6%) and 12,921 females included. Patients were predominantly ethnic Chinese (90.5%). Mean follow-up time was 68.8 days. The mean spherical error corrected was -5.90+/-2.57 D (median, -5.625 D), and outcomes were categorized into low, moderate, or high myopia. The UCVA achieving > or =20/40 has been consistently above 90% since 2000, with 72.8% achieving > or =20/20. More than 93.0% of eyes achieved within +/-1.00 D target in the last 4 years. An improvement in safety was observed since the start of the study, with the best outcomes observed in 2007; loss of 1 and 2 Snellen line BCVA postoperatively was 2.4% and 0.1%, respectively. The overall retreatment rate was 3.8%; 91% of retreated eyes achieved UCVA of > or =20/30. Between 1998 and 2007, there was a significant improvement in postoperative UCVA and BCVA (P<0.001). CONCLUSIONS: Myopic LASIK performed in Asian eyes within a comprehensive LASIK clinical program with appropriate clinical audit governance can be safe and effective, with high refractive predictability. Improvements in the nomograms to prevent undercorrection and to compensate for myopic regression have led to better efficacy after LASIK, with an increasing percentage of patients achieving 20/15 visual acuity postoperatively.

Comparison of the Visian ICL and Verisyse phakic intraocular lenses for myopia from 6.00 to 20.00 diopters.

PURPOSE: To compare visual and refractive outcomes between the Visian Implantable Collamer Lens (ICL) and Verisyse phakic intraocular lens. METHODS: Comparative interventional case series for myopia between 6.00 and 20.00 diopters (D). Thirty consecutive eyes of 16 patients had a Visian ICL implanted and 31 consecutive eyes of 19 patients had the Verisyse lens implanted. Outcomes measured at 3 months postoperatively included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and refractive predictability as well as adverse events. Preoperatively, the groups were no different in regard to age (P=.72) and spherical equivalent refraction (P=.38). RESULTS: Postoperative UCVA of 20/20 or better and 20/25 or better in the Visian ICL group was 67% and 96%, respectively, compared to 63% and 79%, respectively, in the Verisyse lens group (P=.10). Binocular UCVA of 20/20 or better and 20/25 or better in the Visian ICL group was 92% and 100%, respectively, and in the Verisyse group, 70% and 80%, respectively (P=.007). One and two lines gain of postoperative BSCVA in the Visian ICL group was 40% and 10%, respectively, which was statistically significantly better than the Verisyse group of 16% and 6%, respectively (P=.025). Postoperative deviation from target refraction was 0.038+/-0.39 D in the Visian ICL group and -0.38+/-0.89 D in the Verisyse lens group (P=.018). CONCLUSIONS: Monocular UCVA was similar for both groups, whereas binocular UCVA was better in the Visian ICL group. The Visian ICL group had more accurate refractive outcomes than the Verisyse lens group.

Effect of nepafenac sodium 0.1% on delayed corneal epithelial healing and haze after photorefractive keratectomy: retrospective comparative study.

PURPOSE: To assess delayed epithelialization and corneal haze related to nepafenac ophthalmic suspension 0.1% (Nevanac) use after photorefractive keratectomy (PRK). SETTING: Private practice, Beverly Hills, California, USA. METHODS: This retrospective comparative chart review comprised 69 eyes (44 patients) that were divided into 2 treatment groups that were not statistically significantly different in age or preoperative spherical equivalent. The nepafenac group consisted of 34 eyes (22 patients) that received nepafenac 0.1%, moxifloxacin, and fluorometholone postoperatively. The non-nepafenac group included 35 eyes (22 patients) that received moxifloxacin and fluorometholone only. Patients were seen between 1 day and 5 days postoperatively for evaluation of epithelial healing and haze formation. Delayed epithelialization was defined as healing after day 5. All patients were followed for haze formation for a minimum of 3 months. RESULTS: Statistical analysis showed no difference between the nepafenac and non-nepafenac groups in delayed epithelialization (P = .61, chi-square test). Neither group had significant corneal haze. CONCLUSION: Nepafenac did not appear to delay corneal epithelial healing or contribute to haze formation after PRK.