Displaying all 10 publications

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  1. Al-Timemy AH, Mosa ZM, Alyasseri Z, Lavric A, Lui MM, Hazarbassanov RM, et al.
    Transl Vis Sci Technol, 2021 12 01;10(14):16.
    PMID: 34913952 DOI: 10.1167/tvst.10.14.16
    Purpose: To develop and assess the accuracy of a hybrid deep learning construct for detecting keratoconus (KCN) based on corneal topographic maps.

    Methods: We collected 3794 corneal images from 542 eyes of 280 subjects and developed seven deep learning models based on anterior and posterior eccentricity, anterior and posterior elevation, anterior and posterior sagittal curvature, and corneal thickness maps to extract deep corneal features. An independent subset with 1050 images collected from 150 eyes of 85 subjects from a separate center was used to validate models. We developed a hybrid deep learning model to detect KCN. We visualized deep features of corneal parameters to assess the quality of learning subjectively and computed area under the receiver operating characteristic curve (AUC), confusion matrices, accuracy, and F1 score to evaluate models objectively.

    Results: In the development dataset, 204 eyes were normal, 123 eyes were suspected KCN, and 215 eyes had KCN. In the independent validation dataset, 50 eyes were normal, 50 eyes were suspected KCN, and 50 eyes were KCN. Images were annotated by three corneal specialists. The AUC of the models for the two-class and three-class problems based on the development set were 0.99 and 0.93, respectively.

    Conclusions: The hybrid deep learning model achieved high accuracy in identifying KCN based on corneal maps and provided a time-efficient framework with low computational complexity.

    Translational Relevance: Deep learning can detect KCN from non-invasive corneal images with high accuracy, suggesting potential application in research and clinical practice to identify KCN.

    Matched MeSH terms: Corneal Topography
  2. Md. Muziman Syah, M. M., Mutalib, H. A., Sharanjeet Kaur, M. S., Khairidzan Khairidzan, M. K.
    MyJurnal
    Introduction: The purpose of this study was to evaluate inter-session repeatability, inter-examiner
    reproducibility and inter-device agreement of corneal power measurements from manual keratometer,
    autokeratometer, topographer, Pentacam high resolution and IOLMaster. Methods: Two sets of mean
    corneal power measurements (n=40) were compared for inter-session repeatability and inter-examiner
    reproducibility in each instrument. Repeatability and reproducibility were evaluated by within-subject
    standard deviation (Sw), coefficient of variation (COV) and intraclass correlation coefficient (ICC). A oneway
    repeated measures analysis of variance was conducted to compare differences in the corneal power
    between each instrument pair. The Bland and Altman analysis and Pearson’s correlation were employed to
    assess agreement and determine strength of relationship between measurements. Results: There were no
    significant differences in mean corneal power measurements between 2 different visits (p > 0.05). The Sw
    and COV values between 2 visits were lower than 0.09 D and 0.20 % respectively. The ICCs were stronger
    than 0.99 in all instruments. For reproducibility of each instrument, differences of the measurements
    between 2 different examiners were also insignificant (p > 0.05). The Sw and COV values between 2
    examiners were lower than 0.11 D and 0.23 % respectively. The ICCs were 0.99 and above in all instruments.
    The 95% limit of agreement between instruments ranged from -0.29 to 1.13 D and the r-values were stronger
    than 0.84. Conclusion: The corneal power measurements using these 5 instruments were repeatable and
    reproducible. These instruments can also be used interchangeably, however the topographer should be used
    with caution.
    Matched MeSH terms: Corneal Topography
  3. Abolbashari F, Mohidin N, Ahmadi Hosseini SM, Mohd Ali B, Retnasabapathy S
    Cont Lens Anterior Eye, 2013 Aug;36(4):191-5.
    PMID: 23375190 DOI: 10.1016/j.clae.2013.01.005
    To assess changes in anterior segment parameters of keratoconus eyes at different stages of the disease in a sample of the Asian population.
    Matched MeSH terms: Corneal Topography/standards*; Corneal Topography/statistics & numerical data*
  4. Mutalib HA, Ghosh S, Sharanjeet-Kaur, Ghoshal R
    Clin Optom (Auckl), 2016;8:79-83.
    PMID: 30214352 DOI: 10.2147/OPTO.S106421
    A 22-year-old Indian female was referred to Sg Buloh hospital with the diagnosis of bilateral keratoconus. On examination, slit lamp biomicroscopy and corneal topography revealed stage 3 keratoconus in the right eye and stage 2 keratoconus in the left eye. Corneal cell morphology in both eyes was evaluated using confocal microscope. In qualitative observation, almost all corneal layers in right eye except endothelium were partially or completely obscured by haze. Additionally, morphological alterations, such as elongation of keratocyte nuclei and cluster of cells, and dark bands in the anterior stroma were observed in right eye. In the left eye, the amount of haze was less, allowing better visibility of the corneal layers compared with the right eye. The dark bands were evident in the posterior stroma. Quantitative analysis showed that anterior and posterior stromal keratocyte density and endothelium cell density were relatively low in the right eye (834.0, 700.5, and 2,133 cells/mm2, respectively) compared with the left eye (934.1, 750.6, and 2,361 cells/mm2, respectively). In this case, the right eye, exhibiting stage 3 keratoconus, showed more morphological alteration, particularly in the anterior stroma compared with the left eye with stage 2 keratoconus. Increased severity of the disease can explain these differences in corneal cell morphology.
    Matched MeSH terms: Corneal Topography
  5. Noor RA
    Malays J Med Sci, 2003 Jul;10(2):91-2.
    PMID: 23386804 MyJurnal
    Primary pterygium in children is uncommon but is associated with severe visual problems. Astigmatism is the main visual problem caused by pterygium. Significant amounts of astigmatism occur long before a pterygium encroaches the visual axis. Early surgical intervention is safe and effective. It is associated with significant visual improvement in outcome. This is a case report on seven-year-old Malay boy who presented with a growth over nasal aspect of the right eye of 1 year duration. His right eye visual acuity is affected up to 6/12. The dilemma pased to early surgical interview is the high rate of recurrancean the young age group. This problem is highlighted in this case report.
    Matched MeSH terms: Corneal Topography
  6. Lim KL, Fam HB
    J Cataract Refract Surg, 2006 Nov;32(11):1814-9.
    PMID: 17081863
    To determine the values for the anterior best-fit sphere (BFS) and posterior BFS in an Asian population using the Orbscan II (Bausch & Lomb) slit-scanning Placido disk corneal topographer.
    Matched MeSH terms: Corneal Topography/methods*
  7. Choo MM, Yeong CM, Grigg JR, Khaliddin N, Kadir AJ, Barnes EH, et al.
    Medicine (Baltimore), 2018 Nov;97(48):e13357.
    PMID: 30508927 DOI: 10.1097/MD.0000000000013357
    To report observations of horizontal corneal diameter (HCD) and central corneal thickness (CCT) changes in premature infants with stable optic disc cupping and intraocular pressures (IOPs). The HCD and CCT at term serve as a baseline for premature infants.Sixty-three premature infants were enrolled in a prospective case series. HCD, CCT, and IOP were measured. RetCam images of the optic discs were used to evaluate the cup-disc ratio (CDR) and read by an independent masked observer. Data were collected at between preterm (32-36 weeks) and again at term (37-41 weeks) postconceptual age. Left eye measurements were used for statistical analysis. Left eye findings were combined to construct predictive models for HCD and CCT.The mean HCD was 9.1 mm (standard deviation [SD] = 0.7 mm) at preterm and 10.0 mm (SD = 0.52 mm) at term. The mean CCT preterm was 618.8 (SD = 72.9) μm and at term 563.9 (SD = 50.7) μm, respectively. The average preterm CDR was 0.31 and at maturity was 0.33. Average IOP of preterm and term was 13.1 and 14.11 mm Hg, respectively. There was significant linear correlation between HCD with the postmenstrual age (r = 0.40, P Corneal diameter correlated with gestational age at birth and head circumference.
    Matched MeSH terms: Corneal Topography/methods
  8. Ahmadi Hosseini SM, Mohidin N, Abolbashari F, Mohd-Ali B, Santhirathelagan CT
    Int Ophthalmol, 2013 Apr;33(2):139-45.
    PMID: 23138667 DOI: 10.1007/s10792-012-9654-x
    To evaluate corneal thickness and volume in subclinical and clinical keratoconus in Asian population with the aim of discriminating between normal and ectatic cornea. Eyes were placed into one of the following three groups: normal, subclinical, and mild-moderate keratoconus. Pentacam Scheimpflug imaging (Oculus Inc., Wetzlar, Germany) was performed for each participant to record thinnest corneal thickness, central corneal thickness, corneal volume (CV), peripheral corneal thickness (PCT) and percentage thickness increase (PTI) at 2, 4, 6, and 8 mm. The data were exported to SPSS for statistical analysis. Subjects comprised 52 normal, 15 subclinical keratoconus, and 32 mild-moderate clinical keratoconus eyes. Our results indicated that corneal thickness (CT) distribution, PTI, and CV in normal eyes were significantly different compared with subclinical and clinical keratoconus (P < .05). Overall, subclinical group exhibited lower CT distribution and volume, and higher PTI in comparison with normal eyes. However, they showed higher CT distribution and volume, and lower PTI compared with keratoconus group. In addition, there was a smaller change in PCT and PTI from the thinnest point of the cornea to the periphery. The results of the present study indicate that CT parameters and CV were significantly different in normal versus subclinical group and in normal versus keratoconus group. These findings could help clinicians to better discriminate between normal and ectatic cornea.
    Matched MeSH terms: Corneal Topography/methods
  9. Lim KL, Fam HB
    J Cataract Refract Surg, 2009 Dec;35(12):2144-8.
    PMID: 19969221 DOI: 10.1016/j.jcrs.2009.06.031
    PURPOSE: To determine the distribution of higher-order corneal and ocular aberrations in a healthy refractive surgery population.
    SETTING: Island Hospital, Penang, Malaysia.
    METHODS: In this prospective observational study, 1 eye of ethnic Chinese refractive surgery patients was evaluated with an Orbscan II corneal topographer and a Zywave Hartmann-Shack aberrometer with a 6.0 mm pupil. Height data were analyzed to derive the higher-order aberrations (HOAs) from the 3rd to 5th Zernike order.
    RESULTS: The mean spherical equivalent in the 70 eyes evaluated was -6.46 diopters +/- 3.10 (SD). The mean total corneal HOA was 0.574 +/- 0.218 microm (range 0.269 to 1.249 microm) and the mean total ocular HOA, 0.525 +/- 0.354 microm (range 0.138 to 2.145 microm). There was no statistically significant correlation with age. The mean 3rd-order ocular aberration was 0.399 +/- 0.287 microm; the mean 4th-order, 0.297 +/- 0.223 microm; and the mean 5th-order, 0.108 +/- 0.101 microm. Corneal spherical aberration was greater than ocular spherical aberration (mean 0.312 +/- 0.114 microm versus 0.200 +/- 0.170 microm). Multilinear regression showed that the only dependent that predicted ocular spherical aberration was anterior corneal asphericity (r(2) = 0.227, F = 17.95, PCorneal and ocular aberrations in South East Asian Chinese eyes were significantly greater than that reported in other populations. Population differences in wavefront errors were significant, and this should be noted in patient management.
    Matched MeSH terms: Corneal Topography
  10. Chen H, Lin H, Lin Z, Chen J, Chen W
    BMC Ophthalmol, 2016 May 01;16(1):47.
    PMID: 27138378 DOI: 10.1186/s12886-016-0221-5
    BACKGROUND: Ocular biometry is important for preoperative assessment in cataract and anterior segment surgery. The purpose of this study was to investigate normative ocular biometric parameters and their associations in an older Chinese population.

    METHODS: This was a cross-sectional observational study. From 2013 to 2014, we recruited inhabitants aged 50 years or older in Guangzhou, China. Among 1,117 participants in the study, data from 1,015 phakic right eyes were used for analyses. Ocular parameters including axial length (AL), anterior chamber depth (ACD), and corneal curvature (K) were measured using an IOL Master.

    RESULTS: The mean AL, ACD, and K were 23.48 mm [95 % confidence interval (CI), 23.40-23.55], 3.03 mm (CI, 3.01-3.05), and 44.20 mm (CI, 44.11-44.29), respectively. A mean reduction in ACD with age was observed (P = 0.002) in male subjects but not in female subjects (P = 0.558). Male subjects had significantly longer ALs (23.68 mm versus 23.23 mm, P 

    Matched MeSH terms: Corneal Topography
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