PEDIATRIC RETINAL DETACHMENT IN AN ASIAN POPULATION WITH HIGH PREVALENCE OF MYOPIA: Clinical Characteristics, Surgical Outcomes, and Prognostic Factors.

PURPOSE: To evaluate the clinical characteristics and surgical outcomes of pediatric retinal detachments (RDs) in an Asian population. METHODS: Retrospective review of 171 eyes of 152 pediatric patients with rhegmatogenous RD over a 20-year period. RESULTS: Myopia was the most common risk factor in our population. At 6 months, primary anatomical success was 60.7%, and overall anatomical success was 86.7%. A total of 46.8% had best-corrected visual acuity of 20/40 or better, and 81.6% had best-corrected visual acuity of 20/200 or better. In primary RDs, high myopia (≤-6D) patients had a lower primary anatomical success compared to patients with moderate myopia (≤-2D) (59.3 vs. 100% P = 0.03). Increasing age and absence of proliferative vitreoretinopathy were associated with anatomical and visual success. Pars plana vitrectomy as the primary procedure was associated with decreased odds of anatomical success. A longer duration of symptoms, cataract, and a larger RD extent were associated with poorer functional outcome. CONCLUSION: Myopia was the commonest risk factor for pediatric RD in our population. Good anatomical and functional outcome can be achieved with surgery. Increasing age at presentation and absence of proliferative vitreoretinopathy was associated with anatomical and functional success. High myopia was associated with poorer anatomical and functional outcome.

Eye size and shape in newborn children and their relation to axial length and refraction at 3 years.

PURPOSE: To determine if eye size and shape at birth are associated with eye size and refractive error 3 years later. METHODS: A subset of 173 full-term newborn infants from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) birth cohort underwent magnetic resonance imaging (MRI) to measure the dimensions of the internal eye. Eye shape was assessed by an oblateness index, calculated as 1 - (axial length/width) or 1 - (axial length/height). Cycloplegic autorefraction (Canon Autorefractor RK-F1) and optical biometry (IOLMaster) were performed 3 years later. RESULTS: Both eyes of 173 children were analysed. Eyes with longer axial length at birth had smaller increases in axial length at 3 years (p < 0.001). Eyes with larger baseline volumes and surface areas had smaller increases in axial length at 3 years (p < 0.001 for both). Eyes which were more oblate at birth had greater increases in axial length at 3 years (p < 0.001). Using width to calculate oblateness, prolate eyes had smaller increases in axial length at 3 years compared to oblate eyes (p < 0.001), and, using height, prolate and spherical eyes had smaller increases in axial length at 3 years compared to oblate eyes (p < 0.001 for both). There were no associations between eye size and shape at birth and refraction, corneal curvature or myopia at 3 years. CONCLUSIONS: Eyes that are larger and have prolate or spherical shapes at birth exhibit smaller increases in axial length over the first 3 years of life. Eye size and shape at birth influence subsequent eye growth but not refractive error development.

Comparison of swept source optical coherence tomography and spectral domain optical coherence tomography in polypoidal choroidal vasculopathy.

BACKGROUND: Swept source optical coherence tomography (SS-OCT, Topcon Medical System, Japan) is known to have longer wavelength than spectral domain OCT (SD-OCT, Spectralis, Heidelberg Engineering, Germany), allowing a deeper penetration into retina and choroidal layers. This objective of this study was to compare the visibility of retinal and choroidal features in polypoidal choroidal vasculopathy (PCV) using SS-OCT and SD-OCT. DESIGN: This study employs prospective comparative observational case series in Singapore National Eye Center. PARTICIPANTS: There were 20 eyes (20 patients) with PCV confirmed with indocyanine green angiogram. METHODS: Six pre-specified OCT parameters (presence of polyps, sharp pigment epithelial detachment [PED] peak, notched PED and visibility of full maximum height of PED, inner segment/outer segment [IS/OS] line and choroid-scleral interface [CSI]) were graded using SS-OCT and SD-OCT. MAIN OUTCOME MEASURES: The Kappa statistics between the two imaging modalities were calculated. RESULTS: Both SS-OCT and SD-OCT were able to detect polypoidal lesions in the majority of eyes (90% and 85%, respectively). However, SS-OCT had better detection for CSI and IS/OS lines (CSI: 80% vs 45%, P = 0.05; IS/OS line: 65% vs 45%, P = 0.34). For sharp PED peak, notched PED, ability to visualize the full PED height and retinal pigment epithelial line, both OCT machines were able to detect in ≥80% of the eyes. CONCLUSION: In conclusion, SS-OCT and SD-OCT appeared to be similarly effective at detecting most features associated with PCV. However, SS-OCT is more superior in detecting the CSI.

A Novel Bioresorbable Implant for Repair of Orbital Floor Fractures.

PURPOSE: To describe clinical, radiologic, and safety outcomes of orbital floor fracture repair using a novel bioresorbable polycaprolactone (PCL) mesh implant (Osteomesh™, Osteopore International, Singapore). METHODS: This is a prospective interventional case series of orbital floor fractures repaired using a novel PCL mesh implant. Clinical evaluation was conducted at presentation and postoperatively at 1, 4, 12, 24 and 48 weeks. Computed tomography (CT) of the orbits was performed 1 year postoperatively. RESULTS: A total of 20 patients were recruited. Mean follow up was 50.4 ± 31.88 weeks. The majority of the patients were male (60%) and of Chinese ethnicity (75%), and the mean age was 39.35 (range 13-69) years. The most common mechanism of injury was assault. The average fracture size was 21.9 mm (range 12-32 mm) in the anteroposterior meridian and 18.65 mm (range 6-27 mm) in the horizontal meridian. Fifty percent of the patients were classified as having a large orbital defect (horizontal width ≥20 mm). The binocular single vision (BSV) score improved from 72.1% preoperatively to 90.8% postoperatively (P < 0.05) for 17 patients who had pre and postoperative charts. BSV improvement did not differ significantly between those with large and small orbital fracture sizes. There were features of neobone formation on CT scan performed 1.5 years after implantation. CONCLUSION: This bioresorbable implant is a promising material for the repair of both small and large orbital floor fractures, giving good functional and aesthetic outcomes.

Prognostic factor analysis of vitrectomy for retinal detachment associated with myopic macular holes.

PURPOSE: To describe the anatomic and functional outcomes in a cohort of subjects undergoing vitrectomy for retinal detachment (RD) resulting from myopic macular hole (MH) and to analyze the prognostic and surgical factors predicting retinal reattachment and MH closure. DESIGN: Retrospective case series. PARTICIPANTS: All patients who underwent vitrectomy for RD resulting from myopic MH between 2000 and 2009 at our center. METHODS: Case records were reviewed at 6 months after surgery. Retinal reattachment and complete anatomic success, defined as retinal reattachment with MH closure, were assessed. Multivariate logistic regression models, including age, gender, duration of symptoms, spherical equivalent refraction (SE), internal limiting membrane peeling, tamponade choice, and concurrent scleral buckling, were constructed to assess associations with covariates. MAIN OUTCOME MEASURES: Retinal reattachment and complete anatomic success (retinal reattachment with MH closure). RESULTS: In total, 114 subjects were analyzed. Most were women (n = 79 [69.3%]), and the mean age was 57.5±13.3 years. The mean SE was -9.88±6.37 diopters. At 6 months, 98 subjects (86.0%) demonstrated retinal reattachment, of whom 93 subjects required only 1 operation. Complete anatomic success was achieved in 61 subjects (53.5%), of whom 55 needed only 1 operation. Subjects with retinal reattachment had better best-corrected visual acuity (BCVA; mean BCVA, 1.22±0.81 logarithm of the minimum angle of resolution [logMAR] units) than those without (mean BCVA, 1.98±1.26 logMAR units; P < 0.001), and subjects with complete anatomic success had better BCVA (mean BCVA, 1.05±0.87 logMAR units) than those without (mean BCVA, 1.62±0.87 logMAR units; P < 0.001). In multivariate analyses, increasing age and the use of perfluoropropane (C3F8) tamponade were predictive of anatomic success (per 1-year increase: odds ratio [OR], 1.049; 95% confidence interval [CI], 1.002-1.099; P = 0.04; and for tamponade: OR, 10.71; 95% CI, 1.08-106.29; P = 0.04). CONCLUSIONS: Vitrectomy is effective in the repair of RD resulting from MH in myopic eyes, with retinal reattachment achieved more frequently than MH closure. Retinal reattachment and MH closure are important for improving visual outcomes. Greater age at presentation and use of C3F8 are associated with a greater likelihood of anatomic success.

Age-related macular degeneration.

Age-related macular degeneration is a major cause of blindness worldwide. With ageing populations in many countries, more than 20% might have the disorder. Advanced age-related macular degeneration, including neovascular age-related macular degeneration (wet) and geographic atrophy (late dry), is associated with substantial, progressive visual impairment. Major risk factors include cigarette smoking, nutritional factors, cardiovascular diseases, and genetic markers, including genes regulating complement, lipid, angiogenic, and extracellular matrix pathways. Some studies have suggested a declining prevalence of age-related macular degeneration, perhaps due to reduced exposure to modifiable risk factors. Accurate diagnosis combines clinical examination and investigations, including retinal photography, angiography, and optical coherence tomography. Dietary anti-oxidant supplementation slows progression of the disease. Treatment for neovascular age-related macular degeneration incorporates intraocular injections of anti-VEGF agents, occasionally combined with other modalities. Evidence suggests that two commonly used anti-VEGF therapies, ranibizumab and bevacizumab, have similar efficacy, but possible differences in systemic safety are difficult to assess. Future treatments include inhibition of other angiogenic factors, and regenerative and topical therapies.

Association of macular and choroidal perfusion with long-term visual outcomes after macula-off rhegmatogenous retinal detachment.

BACKGROUND/AIMS: To examine the relationship between macular perfusion, as assessed using optical coherence tomography angiography (OCTA), and long-term visual outcome after surgical repair of macula-off rhegmatogenous retinal detachment (RRD). METHODS: A prospective study of 29 patients who had undergone successful surgical repair of macula-off RRD. OCTA imaging was performed at month 3 and repeated at months 6 and 12 after surgery. Associations between OCTA parameters including, foveal avascular zone (FAZ) area, vessel density (VD) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), choriocapillaris flow deficit features and logMAR best-corrected visual acuity (VA) were assessed using a random intercept hybrid linear mixed model. RESULTS: Over the 1-year follow-up, VA improved (0.025 logMAR/ month, 95% CI 0.015 to 0.035) and FAZ area decreased (-0.020 mm2/month, 95% CI -0.032 to -0.007). Better VA after surgery was significantly associated with denser superficial VD (ß=0.079, 95% CI 0.026 to 0.131), lower number of choriocapillaris flow deficits (ß=-0.087, 95% CI -0.154 to -0.021) and larger average size of choriocapillaris flow deficits (ß=0.085, 95% CI 0.022 to 0.147), after adjusting for baseline VA, types of surgery and other factors. CONCLUSIONS: OCTA measures of vascular perfusion in the macula may provide new pathophysiological insights and prognostic information related to macula-off RRD.

Myopia-related optic disc and retinal changes in adolescent children from singapore.

PURPOSE: To examine early myopia-related optic disc and retinal changes in a Singapore Chinese adolescent sample without confounding ocular or systemic disease. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Children aged 12 to 16 years at a follow-up visit for Singapore Cohort Study of Risk Factors for Myopia. METHODS: Detailed eye examinations, including cycloplegic autorefraction and contact biometry, were performed. Retinal photographs were acquired using nonmydriatic retinal photography among children who attended follow-up examinations in 2006, and were graded for myopia-related optic disc signs and macular changes by a single experienced grader. Optic nerve head parameters were measured adjusting for camera and ocular magnification with appropriate formulae. MAIN OUTCOME MEASURES: Optic disc changes (tilt, beta peripapillary atrophy [ß-PPA], and optic nerve parameters) and macular changes (staphyloma, lacquer cracks, Fuchs' spot, and chorioretinal atrophy). RESULTS: Retinal photography data were available for 1227 children (median age, 14 years; range 12-16). Tilted optic discs were found in 454 subjects (37%), and were associated with myopic spherical equivalent refractions (-3.6 diopters [D] vs -1.3 D; P<0.0001), higher cylindrical error (0.9 vs 0.7 D; P = 0.0001) and longer axial length (24.93 vs 23.96 mm; P<0.0001). The pattern of distribution of the axes of the tilted discs and corneal curvature were similar (P = 0.4). All linear optic nerve parameters, except vertical disc diameter (P = 0.15), were significantly smaller in eyes with than without tilted discs (P <0.001) after adjusting for confounders. Apart from 20 cases, all eyes with tilted optic discs had associated ß-PPA. We identified only 1 case each (0.1% prevalence) of staphyloma and lacquer cracks in this sample. CONCLUSIONS: In this Asian adolescent population, tilted optic discs were highly prevalent, in contrast with the lower prevalence reported in Caucasian populations. Eyes with tilted discs tended to have smaller optic cups with smaller cup-to-disc ratios, and were associated with myopic refraction, higher astigmatism, and longer axial length. There were similar patterns of distribution between the axis of disc tilt and the axis of corneal curvature, which could have embryologic origins. In contrast with optic disc changes, myopic macular changes were rare in this age group, suggesting that these changes may develop later in life. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

1 Year Surgical Outcomes and Safety of Combined Trans Pars Plana Vitrectomy with Iris Fixated Posterior Chamber Intraocular Lens for Subluxated Intraocular Lens and Cataracts.

IMPORTANCE/BACKGROUND: To describe the characteristics and 1-year postoperative surgical outcomes of primary combined trans pars plana vitrectomy (TPPV) with iris-fixated posterior-chamber intraocular lens (IF-PCIOL) implantation for subluxated cataracts and intraocular lenses (IOLs). METHODS: Consecutive cases of significantly subluxated cataracts and IOLs from January 2014 to May 2019 were included in this retrospective case series. RESULTS: A total of 103 eyes of 103 patients were included. Median age was 67.4 (interquartile range [IQR] 27-89) years. Thirty-two (31.1%) had subluxated cataracts, while 71 (68.9%) had subluxated IOLs. Overall median preoperative logMAR BCVA was 0.9 (IQR 0-2.5). Median logMAR BCVA improved to 0.3 (0-1.9) and 0.2 (0-1.8) for the subluxated cataract and IOL groups, 81.2% and 75% of eyes achieved logMAR ≤ 0.3, and 94% and 97% achieved IOL stability at month 12, respectively. Eyes with subluxated IOLs had a significantly less myopic median SE if a new IOL was implanted compared to iris-fixating the dislocated IOL. CONCLUSION: Combined primary TPPV and IF-PCIOL implantation is a good surgical option for subluxated IOL or cataract without sufficient capsular support, with at least 75% achieving logMAR BCVA ≤ 0.3 and 95% IOL stability at postoperative year 1. In eyes with subluxated IOLs, explanting that IOL and iris-fixating a new IOL led to a reduced SE and better visual outcome at postoperative month 12 when compared to iris-fixating the dislocated IOL.

Are myopic eyes less likely to have diabetic retinopathy?

PURPOSE: Eyes with myopia may be less likely to develop diabetic retinopathy (DR). The relationship between refractive error, ocular biometry, and DR therefore was investigated. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: Persons with diabetes from the Singapore Malay Eye Study (SiMES). METHODS: Diabetes mellitus was defined as random glucose of 11.1 mmol/l or more, use of diabetic medication, or a physician diagnosis of diabetes. Spherical equivalent refraction (SE) was assessed using an autokeratorefractometer and subjective refraction. Axial length (AL) and anterior chamber depth (ACD) were measured by IOLMaster (Carl Zeiss Meditec AG, Jena, Germany). Diabetic retinopathy was graded from retinal photographs. MAIN OUTCOME MEASURES: Any DR was defined by characteristic lesions defined by the Early Treatment Diabetic Retinopathy Study (ETDRS); moderate DR by ETDRS retinopathy severity scores of 43 or higher; and vision-threatening retinopathy by severe nonproliferative retinopathy, proliferative DR, or clinically significant macular edema. RESULTS: Of 3280 adult Malay participants (78.7% response), 629 persons with diabetes contributed to this analysis. In multivariate analyses adjusting for age, gender, education, height, cataract, hypertension, hemoglobin A1c, and other factors, eyes with myopic SE were less likely to have any DR (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.84-0.96; P = 0.002, per 1-diopter [D] decrease), moderate DR (OR, 0.83; 95% CI, 0.73-0.93; P = 0.001, per 1-D decrease), and vision-threatening DR (OR, 0.77; 95% CI, 0.67-0.88; P<0.001, per 1-D decrease). Eyes with longer AL were less likely to have any DR (OR, 0.86; 95% CI, 0.75-0.99; P = 0.041, per 1-mm increase), moderate DR (OR, 0.80; 95% CI, 0.62-1.05; P = 0.11, per 1-mm increase), and vision-threatening DR (OR, 0.63; 95% CI, 0.40-0.99; P = 0.044, per mm increase). Eyes with deeper ACD were less likely to have moderate DR (OR, 0.32; 95% CI, 0.16-0.64; P = 0.001, per 1-mm increase) and vision-threatening DR (OR, 0.14; 95% CI, 0.06-0.36; P = 0.001, per 1-mm increase). CONCLUSIONS: Myopic refraction and longer AL are associated with a lower risk of DR, particularly vision-threatening retinopathy, without any evidence of a threshold.

Dietary factors, myopia, and axial dimensions in children.

PURPOSE: To evaluate the possible associations between dietary factors and myopia. DESIGN: Cross-sectional study. PARTICIPANTS: Eight hundred fifty-one Chinese schoolchildren from the Singapore Cohort Study of Risk Factors for Myopia. METHODS: Diet was assessed using a semiquantitative food-frequency questionnaire. Spherical equivalent (SE) refraction was assessed with an autorefractometer, and axial length (AL) by contact ultrasound A-scan biometry. MAIN OUTCOME MEASURES: Myopia was defined as SE< or =-0.5 diopters (D). Spherical equivalent and AL were analyzed by quartile groups. RESULTS: The mean age (+/-standard deviation) was 12.81+/-0.83 years, approximately half were male (422 children [49.6%]), and 653 (73.8%) children had myopia. In multivariate models, AL was longest in the highest quartile group of total cholesterol intake compared with the lowest (adjusted mean [95% confidence interval], 24.66 [24.62-24.71] mm vs. 24.32 [24.27-24.36] mm; P = 0.026, for trend) and was longest in the highest quartile group of saturated fat intake compared with the lowest (24.65 [24.60-24.70] vs. 24.36 [24.32-24.41] mm; P = 0.039, for trend). None of the nutrients was associated with SE or a diagnosis of myopia. CONCLUSIONS: Higher saturated fat and cholesterol intake are associated with longer AL in otherwise healthy Singapore Chinese schoolchildren.

MRI of posterior eye shape and its associations with myopia and ethnicity.

PURPOSE: To evaluate posterior eye shape variations across a wide refractive error range using brain MRI in a multiethnic cohort. METHODS: Adult subjects in the multiethnic Singapore Epidemiology of Eye Disease study were included. Spherical equivalent (SE) was measured using subjective refraction, and axial length (AL) was measured using optical biometry. MRI was performed using a 3-Tesla whole body scanner with a 32-channel head coil. The radii and asphericity based on fitting of the posterior two-thirds of the eye (240°) were calculated. The refractive error status was categorised as myopic (SE<-0.5 D) or non-myopic (SE≥-0.5 D). RESULTS: A total of 450 adult participants (mean age 64.2±6.5 years old) were included. Less oblate asphericity was associated with more myopic SE, longer AL and with a refractive error categorisation of myopia (p<0.001 for all). Asphericity values were less oblate in myopic compared with non-myopic eyes (p<0.001). Multivariate analysis showed that Chinese subjects had less oblate eyes than Malay and Indian subjects, especially in non-myopic eyes. CONCLUSIONS: A less oblate posterior eye shape was associated with myopic eyes. Chinese eyes have less oblate shapes than Malay and Indian eyes, especially in non-myopic eyes.

25-years Trends and Risk factors related to Surgical Outcomes of Giant Retinal Tear-Rhegmatogenous Retinal Detachments.

To describe the 25-year surgical trends, long-term outcomes and risk factors affecting the outcomes of giant retinal tear-related rhegmatogenous retinal detachments (GRT-RRD). Patients' demographics, pre-operative characteristics, risk factors, operative procedures and post-operative outcomes were collected and divided into three groups - Group A: 1991 to 2015 (overall); Group B: 1991 to 2005, and Group C: 2006 to 2015. Functional and anatomical successes were monitored over a 5-year period. Multivariate logistic regression analysis was performed to identify the risk factors related to functional and anatomical success.127 eyes of 127 patients were included in the study. At 5th year, 69.4% patients had visual acuity (VA) < logMAR 1.0 with 87.5% primary anatomical success rate. While the functional outcome remained the same between group B and C, there was an increase in the anatomical success from 89.7% to 100%, albeit not statistically significant. Patients with worse presenting VA, 150 degrees or more of giant retina tear, macula-detached status and presence of PVR were associated with VA of> logMAR 1.0 (all p < 0.05). The types of surgery (TPPV vs combined SB/TPPV), number of breaks, lens extraction and additional cryotherapy were not associated with the functional or anatomical success. In conclusion, the GRT-RRD functional and structural outcomes were comparable between 1991-2005 and 2006-2015, albeit a statistically insignificant improvement of anatomical outcome over the past 25 years. Worse presenting VA, 150 degrees or more of giant retinal tear, detached macula and presence of PVR were associated with poorer visual outcome.

Relation of age-related cataract with obesity and obesity genes in an Asian population.

Obesity shows an inconsistent association with cataract. Causality has not been established. Polymorphisms at the fat mass- and obesity-associated (FTO) locus are associated with obesity and offer an opportunity to examine the obesity-cataract association using a mendelian randomization approach. The authors conducted a population-based study among Singaporean Malay adults (2004-2006) in which nuclear, cortical, and posterior subcapsular (PSC) cataracts were assessed and defined by slit-lamp examination using Lens Opacity Classification System III. Obesity was defined as body mass index (weight (kg)/height (m)(2)) > or =30. The study included 3,000 subjects, of whom 1,339 (44.6%) had cataract (848 (28.3%) nuclear, 939 (31.3%) cortical, and 285 (9.5%) PSC). After multivariable adjustment for age, gender, diabetes, hypertension, smoking, and education, obesity was significantly associated with cortical (odds ratio (OR) = 1.31, 95% confidence interval (CI): 1.01, 1.71) and PSC (OR = 1.60, 95% CI: 1.10, 2.32) cataracts but not nuclear cataract. FTO single nucleotide polymorphisms known to be associated with obesity in this study population were not associated with cortical or PSC cataract but were associated with nuclear cataract (OR = 1.33, 95% CI: 1.11, 1.58), even in multivariate analyses controlling additionally for body mass index, diabetes, hypertension, and smoking (OR = 1.30, 95% CI: 1.08, 1.55). These results do not support a causal association between obesity and cortical or PSC cataract. The FTO gene may be involved in the pathogenesis of nuclear cataract.

Effect of dispase denudation on amniotic membrane.

PURPOSE: To describe the cellular components, biochemical composition, and membrane surface characteristics of denuded human amniotic membrane (DHAM) treated with Dispase II. METHODS: DHAM was incubated with Dispase II (1.2 U/ml) for 30 min, 60 min, or 120 min. This was followed by gentle scraping to remove any remaining epithelial cells using a cell scraper. Histology, immunohistochemistry for extracellular matrix molecules and growth factors, and transmission (TEM) and scanning electron microscopy (SEM) were performed to assess the effects of increasing durations of incubation on DHAM structure. RESULTS: Dispase II treatment was associated with the digestion of several ECM molecules, particularly those in the basement membrane including collagen VI, fibronectin, and laminin. FGF-2 and PDGF-B expression were unaffected by Dispase II, but TGF-alpha, TGF-beta1, TGF-beta 2R, PDGF-A, VEGF, and EGFR expression were all reduced by Dispase II incubation. TEM confirmed the disruption of DHAM ultrastructure with increasing duration of Dispase II incubation, beginning with disruption of the basal lamina and progressing to loosening of the stromal collagen network as well. CONCLUSIONS: The use of Dispase II in the preparation of DHAM causes significant changes to the ultrastructure of the membrane, particularly the BM. Prolonged incubation with dispase may cause significant disruption in DHAM structure which may affect cell growth in cultured explants.

Retinal Vascular Oxygen Saturation and Its Variation With Refractive Error and Axial Length.

PURPOSE: To evaluate the relationships between refractive error, axial length (AL), and retinal vascular oxygen saturation in an adult population. METHODS: This was a hospital-based, prospective observational study. The left eyes of phakic adult subjects without media opacity were analyzed. Subjective undilated manifest refraction was performed, and refractive errors were defined as myopia (spherical equivalent [SE], <-1 D), emmetropia (SE between -1 D and +1 D) and hyperopia (SE >+1 D). Retinal oximetry was performed using the Oxymap system (Oxymap Inc., Reykjavik, Iceland). Multivariate linear regression models were constructed to assess the relationship between retinal vascular oxygen saturation, SE, and AL obtained with optical biometry, with adjustments for age, sex, race, blood pressure, hyperlipidemia, and diabetes mellitus. RESULTS: There were 85 subjects, with mean age of 66.1 ± 11.3 years. The majority were female (60%) and Chinese (84%). A total of 60% were myopic, 28% emmetropic, and 12% hyperopic. Mean SE was -5.29 ± 6.51 D and mean AL was 25.30 ± 2.99 mm. In multivariate analyses, more myopic SE and longer AL were associated with lower retinal arteriolar oxygen saturation (regression coefficient B = 0.61 [95% confidence interval, 0.28, 0.95], P = 0.001; and B = -1.13 [95% confidence interval, -1.71, -0.56], P < 0.001, respectively). Subjects with myopic SE and AL also had lower retinal arteriolar oxygen saturation than emmetropes and hyperopes (P = 0.03 and P = 0.02, respectively). CONCLUSIONS: Eyes with more myopic SE and longer AL have lower retinal arteriolar oxygen saturation. TRANSLATIONAL RELEVANCE: This study provides direct evidence of a link between retinal oxygenation and hypoxia and myopia by using a novel device that quantifies retinal vascular oxygenation in vivo.

Penetrating keratoplasty in Asian eyes: the Singapore Corneal Transplant Study.

PURPOSE: The Singapore Corneal Transplant Study (SCTS) is a 16-year prospective study of 2100 consecutive corneal transplants performed between January 1991 and November 2006 in patients from Southeast Asia at a single tertiary center. The indications, complications, long-term survival rates, and risk factors for graft failure of penetrating keratoplasty (PK) performed in Asian eyes are reported. DESIGN: Prospective cohort study. PARTICIPANTS: Of the 2100 corneal transplants, 1130 consecutive PKs were performed from January 1991 to December 2003. One graft per patient was selected, leaving 901 grafts for analysis. METHODS: Data were obtained from the Singapore Eye Bank's SCTS database. Cases were classified into optical, therapeutic, and tectonic indications and 9 corneal disease groups. Twenty-four demographic, preoperative, intraoperative, and donor risk factors were subjected to Kaplan-Meier survival analysis, univariate analysis, and multivariate analysis by Cox proportional hazards regression modeling. MAIN OUTCOME MEASURE: Graft failure, defined as the irreversible loss of optical clarity. RESULTS: Study patients were Asian, comprising Chinese (72.7%), Indian (11.54%), and Malay (11.1%) ethnicities (mean age, 56.65 years). The mean follow-up period was 36.8+/-35.5 months. Indications for surgery were optical (87.0%), therapeutic (8.1%), and tectonic (4.88%). Main diagnoses were pseudophakic/aphakic bullous keratopathy (23.4%), postinfectious scarring (12.9%), regrafts (12.4%), keratoconus (9.7%), and posttraumatic scarring (7.3%). Kaplan-Meier survival rates for optical grafts were 86.6%, 72.0%, 63.7%, and 52.0% at 1, 3, 5, and 10 years, respectively; survival rates for therapeutic grafts were 78.4%, 58.3%, and 37.3% at 1, 3, and 5 years, and those for tectonic grafts were 68.3% and 41.7% at 1 and 3 years. Endothelial rejection and late endothelial decompensation accounted for 50.51% of failures. Multivariate analysis revealed 9 predictors for graft failure: recipient gender, age, graft size, graft endothelial status, primary corneal disease, glaucoma, inflammation, perforation, and corneal vascularization. CONCLUSIONS: The long-term outcome for optical indications in Asian eyes follows a trend in endothelium-related attrition similar to that seen in the West. Tectonic and therapeutic keratoplasty for corneal infections and perforation, however, constitute a significant proportion of corneal transplantation performed in Asia and carry a graver prognosis in terms of graft survival.

Corneal imaging with anterior segment optical coherence tomography for lamellar keratoplasty procedures.

PURPOSE: To assess and describe the uses of anterior segment optical coherence tomography (OCT) in the evaluation of the cornea before and after lamellar corneal transplantation procedures. DESIGN: Prospective, noncomparative, observational case series. METHODS: Seven eyes of seven patients undergoing anterior and posterior lamellar corneal transplantation procedures at the Singapore National Eye Centre were included in the study. High-resolution anterior segment OCT scans of the cornea and anterior segment were performed both before and after lamellar transplantation procedures on the cornea with the Visante anterior segment OCT system (Visante OCT; Carl Zeiss Meditec, Inc, Dublin, California, USA), and the imaging findings were correlated with the clinical picture. Measurements of lamella thickness were performed with the software provided. RESULTS: Anterior segment OCT images were able to provide valuable information on donor apposition, Descemet membrane detachment after deep anterior lamellar keratoplasty (DALK), posterior lamellar dislocation, primary graft failure, and anterior chamber crowding with consequent chamber angle encroachment and pupillary block after Descemet stripping automated endothelial keratoplasty (DSAEK). CONCLUSIONS: Anterior segment OCT is a valuable imaging tool for assessing the feasibility of lamellar transplantation surgery in the diseased cornea and in the management of surgical complications after such procedures.