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Optical Coherence Tomography Imaging of the Posterior Segment in High Myopia.

This study has been completed.
Sponsor:
Information provided by:
Singapore National Eye Centre
ClinicalTrials.gov Identifier:
NCT00347451
First received: June 30, 2006
Last updated: May 11, 2010
Last verified: May 2010
  Purpose

The prevalence of myopia in East Asia and Singapore in particular is amongst the highest in the world, with estimates ranging from 30-70% of the general population. Up to 30% of these are high myopes. High myopia is associated with degenerative changes in the fundus. It may also be associated with vision-threatening complications such as macular holes. The pathogenesis of macular holes in high myopes is not completely understood but is postulated to include a combination of anterior vitreous traction and posterior staphyloma formation and axial elongation. These forces lead to degenerative changes at the macula, including foveal detachment and retinoschisis that precede the formation of lamellar or full thickness macular holes. These changes are difficult to detect either clinically or by conventional imaging such as ultrasound, making efforts to correct them in the early stages with surgery difficult. High myopia is also associated with a two- to threefold increase in risk of developing glaucoma. However, the diagnosis of glaucoma in high myopes is difficult as many of the pathological changes in the myopic eye mimic those seen in glaucoma. The myopic optic disc in particular is notoriously difficult to differentiate from the glaucomatous disc. Currently, the diagnosis is highly subjective, relying on observations of the clinical appearance of the disc or on disc photos.Optical coherence tomography (OCT) is an evolving technology that relies on time delays of reflected or backscattered light and interferometry to yield cross-sectional images of the retina and optic disc. The Stratus OCT is the latest model and has been demonstrated to be able to yield images with a resolution comparable to that of histology. It is thus potentially useful in assessing degenerative changes occurring in the myopic fundus, in evaluating the early changes preceding macular hole formation, and in providing objective measures of various disc parameters to aid in diagnosing glaucoma in high myopes. This study aims to recruit 150 healthy, young, ophthalmologically normal males from the SAF and to examine them with OCT. High myopes (≤-8D) will be selected and compared with a control group of low myopes. The performance of the OCT will be evaluated against current diagnostic methods.


Condition
Myopia
Maculopathy
Glaucoma

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: Optical Coherence Tomography Imaging of the Posterior Segment in High Myopia.

Resource links provided by NLM:


Further study details as provided by Singapore National Eye Centre:

Estimated Enrollment: 150
Study Start Date: October 2005
Study Completion Date: June 2006
Primary Completion Date: June 2006 (Final data collection date for primary outcome measure)
Detailed Description:

Primary AimThe aim of the study is to evaluate the retinal and macular topography, vitreomacular relationships and optic nerve head changes in highly myopic eyes of young adults. Specific aims include:1) To determine the prevalence of vitreo-macular traction and macular degenerations (macular thickening, detachments, schisis or lamellar holes) in asymptomatic, highly myopic young Asian males using OCT.2) To characterize and measure optic nerve head and peripapillary retinal nerve fibre layer changes in high myopia using OCT.3) To compare OCT findings with current methods of investigation and diagnosis

SubjectsSubjects will be drawn from in-service personnel as well as recruits awaiting enlistment. They will be identified based on their refraction through the SAF's computerized medical records system.Informed consent will be sought from the subjects before commencement. All subjects will be healthy young males and will be ophthalmologically normal apart from myopia. The main exclusion criteria are:1) Best corrected visual acuity <6/92) Previous intraocular surgery3) Intraocular pressure >21mmHg4) Gonioscopic findings of angle closure5) Clinical evidence of pseudo-exfoliation, uveitis or pigment dispersion syndrome, corneal or media opacities, retinal pathology or neurological diseases6) Family history in a first degree relative of glaucoma or other optic neuropathy.Excluded subjects will be replaced by the subject next-in-line in the cohort.ProcedureAll subjects identified will be examined at SNEC/SERI by one of the investigators. The assessment for each subject will include:1) Autorefraction performed with a non-accommodating target and recording of best corrected visual acuity. 2) Slit lamp examination, Goldmann applanation tonometry, gonioscopy, examination with a Goldmann three-mirror lens, and a dilated fundus examination with a 78 diopter fundus lens. Retinal findings are recorded in standard Amsler Dubois retinal diagrams. Grading of background myopic chorioretinal changes will be in accordance with the scheme proposed by Avila . 3) Axial length measurements. Ultrasound A scan is performed for each eye. Axial length is ascertained from the average of six consistent recordings. Care is taken to locate the fovea especially in cases with posterior staphyloma, by ensuring fixation of the A scan probe light. 4) Fundus photography with the Topcon camera. Stereoscopic disc photographs will also be taken for comparison with OCT scans of the optic nerve head.5) OCT using the Stratus OCTOCT measurements will be performed at one sitting by a trained technician. The commercially prescribed Optic Disc, RNFL and Macular Thickness scanning algorithms will be used. Each subject will fixate on an internal target presented by the computer where possible, or an external fixation target for cases unable to cooperate. Subjects will be encouraged to blink between the acquisition of each radial scan to minimize discomfort and minimize the effect of an irregular tear film or corneal desiccation on the tear film. Each scan will take approximately 2.5s, making for a total image acquisition time of less than a minute. The optic nerve head scan consists of six radial scans centered on the optic nerve head. The computer generated disc margin will be used as the reference for optic nerve head measurements. The macular thickness protocol uses six radial scans centered on the fovea. The retinal thickness is measured automatically as the distance between the vitreoretinal interface and the junction between the inner and outer segments of photoreceptors.

  Eligibility

Ages Eligible for Study:   18 Years to 35 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population

Myopic subjects

Criteria

Inclusion Criteria:

  • Healthy young adult males with myopia <-8D

Exclusion Criteria:

  • Best corrected visual acuity <6/9
  • Previous intraocular surgery
  • Intraocular pressure >21mmHg
  • Gonioscopic findings of angle closure
  • Clinical evidence of pseudo-exfoliation, uveitis or pigment dispersion syndrome, corneal or media opacities, retinal pathology or neurological diseases
  • Family history in a first degree relative of glaucoma or other optic neuropathy.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00347451

Locations
Singapore
Singapore National Eye Centre
Singapore, Singapore, 168751
Sponsors and Collaborators
Singapore National Eye Centre
Investigators
Principal Investigator: Laurence S Lim, MBBS Singapore National Eye Centre
Study Director: Tin Aung, PhD Singapore National Eye Centre
Principal Investigator: Bobby C Cheng, FRCS Singapore National Eye Centre
  More Information

Publications:

Responsible Party: Dr Laurence Lim, Singapore National Eye Centre
ClinicalTrials.gov Identifier: NCT00347451     History of Changes
Other Study ID Numbers: R415/10/2005
Study First Received: June 30, 2006
Last Updated: May 11, 2010
Health Authority: Singapore: Health Sciences Authority

Keywords provided by Singapore National Eye Centre:
myopia
optical coherence tomography

Additional relevant MeSH terms:
Myopia
Eye Diseases
Refractive Errors

ClinicalTrials.gov processed this record on November 20, 2014