Original articleEvaluation of Keratoconus in Asians: Role of Orbscan II and Tomey TMS-2 Corneal Topography
Section snippets
Setting
This was a prospective observational study of patients with KC conducted at the Singapore National Eye Centre. The study was approved by the Scientific and Ethics Committee of the Institutional Review Board of the Singapore Eye Research Institute before commencement and funded by the discretionary research fund of the Singapore National Eye Centre and the Singapore Eye Research Institute pilot grant. Informed consent was obtained from all study subjects before commencement of the study.
Study population
Patients
Results
A total of 116 patients were enrolled in the study. Of these, 65 (56%) patients were diagnosed with bilateral KC; 41 (35.3%) patients had clinical KC in one eye and topographic evident KC in the fellow eye, five (4.3%) patients were bilateral KC suspects, and five (4.3%) patients had unilateral KC.
The mean age of the patients was 29.5 years (range, 9.3 to 55 years), males 62.9%, females 37.1%, and the racial distribution was: 60.3% Chinese, 13.8% Malay, 9.5% Indian, and 16.4% of other races
Case 1
A 17-year-old Malay girl, corneal videokeratographs showing the AB/SRAX pattern (Figure 3). Manifest refraction was right eye [OD]: +0.75 D/−7.00 D × 50 degrees (6/6), left eye [OS]: −2.50 D/−0.25 D × 140 degrees (6/6). In her right eye, clinical KC was interpreted in both Tomey indices KCI and KSI. AB/SRAX pattern was displayed in both Tomey and Orbscan maps. However, in her left eye, the KCI and KSI indices did not detect KC suspect, although AB/SRAX pattern was detected. The Orbscan map
Discussion
Thirty percent of eyes with clinical KC had an average corneal curvature of more than 52 D, and 87% of keratoconic eyes had an average keratometric reading of more than 45 D (Table 5). In comparison, 63% of eyes with KC suspect showed an average keratometry of less than 45 D.
The most frequent axial curvature pattern of eyes with clinically evident KC was AB/SRAX (48.6%), followed by AB/IS (19.9%), and SB (9.6%). Hence, corneas with KC mostly have some degree of asymmetry and skewing of the
Lim Li, FRCS (ED), MMed (OPHTH), is a Senior Consultant Ophthalmologist in the Singapore National Eye Centre, Clinical Lecturer in Ophthalmology, National University of Singapore. Dr Li did her undergraduate (MBBS) at the National University of Singapore in 1987 and obtained her Master of Medicine in Ophthalmology from the same University. She also received the Fellowship of the Royal College of Surgeons of Edinburgh. Dr Li has been practicing clinical ophthalmology for more than 10 years, her
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Cited by (62)
Corneal elevation topographic maps assessing different diseases detection: A review
2024, Ain Shams Engineering JournalThe distribution of orbscan indices in young population
2017, Journal of Current OphthalmologyCitation Excerpt :Many studies have investigated the agreement of this device with ultrasound techniques and Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) in measuring important corneal indices like its curvature and thickness.13–18 Moreover, some studies have shown the role of the indices measured by this device in the diagnosis of keratoconus and its progress.19–21 Since these devices require little time and are not expensive, they can also be used in screening programs and epidemiological studies.3,10,22,23
Efficacy of axial and tangential corneal topography maps in detecting subclinical keratoconus
2015, Journal of Cataract and Refractive SurgeryKeratoconus diagnosis with optical coherence tomography-based pachymetric scoring system
2013, Journal of Cataract and Refractive SurgeryA review of corneal imaging methods for the early diagnosis of pre-clinical Keratoconus
2020, Journal of OptometryCitation Excerpt :Identifying a reliable and repeatable method for the early detection of corneal changes will result in earlier diagnosis and management of the condition and subsequently less need for corneal transplants. Topography is currently the go to assessment in the screening and classification of KC.22–24 Numerous topography indices have been developed to facilitate corneal assessments25 with varied sensitivity and specificity, particularly in the diagnosis of preclinical KC.26–28
Lim Li, FRCS (ED), MMed (OPHTH), is a Senior Consultant Ophthalmologist in the Singapore National Eye Centre, Clinical Lecturer in Ophthalmology, National University of Singapore. Dr Li did her undergraduate (MBBS) at the National University of Singapore in 1987 and obtained her Master of Medicine in Ophthalmology from the same University. She also received the Fellowship of the Royal College of Surgeons of Edinburgh. Dr Li has been practicing clinical ophthalmology for more than 10 years, her subspecialty is in the field of cornea, contact lenses, and refractive surgery.
See accompanying Editoral on page 500.