September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Refractive Profile of a Canadian Narrow Angle Population: a Prospective, Consecutive Enrollment Study
Author Affiliations & Notes
  • Edward B Moss
    Ophthalmology, Queen's University, Victoria, British Columbia, Canada
  • Sarah Simpson
    Ophthalmology, Queen's University, Victoria, British Columbia, Canada
  • Harman Singh
    Notre-Dame Hospital, Department of Ophthalmology, University of Montreal, Montreal, Quebec, Canada
  • Isabella Irrcher
    Ophthalmology, Queen's University, Victoria, British Columbia, Canada
  • Delan Jinapriya
    Ophthalmology, Queen's University, Victoria, British Columbia, Canada
  • Footnotes
    Commercial Relationships   Edward Moss, None; Sarah Simpson, None; Harman Singh, None; Isabella Irrcher, None; Delan Jinapriya, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 2594. doi:
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      Edward B Moss, Sarah Simpson, Harman Singh, Isabella Irrcher, Delan Jinapriya; Refractive Profile of a Canadian Narrow Angle Population: a Prospective, Consecutive Enrollment Study. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2594.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To determine the refractive profile and biometric properties of a Canadian narrow angle population.

Methods : This was a prospective, consecutive enrollment cohort study. All treatment-naive patients at a tertiary glaucoma center in Kingston, Ontario with a new diagnosis of primary narrow angles and who could provide consent were invited to participate. Diagnosis required agreement of two glaucoma specialist who used Sussman gonioscopy to grade angles. Right eyes were included for patients with both eyes eligible. Patients were classified as myopic (spherical equivalent (SE) ≤ 0 D) or hyperopic (spherical equivalent > 0 D) based on iProfiler auto-refraction at the time of diagnosis. Ocular biometric parameters were determined by IOL Master (anterior chamber depth, axial length and white to white) and contact A-scan (lens thickness) performed on all patients prior to receiving treatment. Ethics approval from Queen’s University was received in July 2015.

Results : Narrow angles, defined as 360 degrees of Shaffer grade ≤2, were confirmed (within 1 Shaffer grade) by a second glaucoma specialist in 98% of cases (118 of 120). Of 118 eyes eligible for analysis, 97% (114 of 118) belonged to self-reported Caucasian patients. 29% (n=34) were myopic, 71% were hyperopic (n=84) and 80% (n=95) had a refractive status between 2 D and -2 D. 3% (n=3) were highly myopic with a SE greater than 4 D of myopia. Biometric testing revealed longer axial lengths in myopic (23.3 mm) compared to hyperopic (22.9 mm) patients, p = 0.05. There was no difference in axial lenticular thickness (4.66 mm vs 4.76 mm), anterior chamber depth (2.81 mm vs 2.84 mm), or white-to-white diameter (11.9 mm vs 11.9 mm) between the myopic and hyperopic groups respectively.

Conclusions : In this consecutive series of a Canadian narrow angle cohort, which was predominantly Caucasian, over 25% with narrow angles were myopic. Furthermore, over three quarters were within 2D of emmetropia suggesting a high prevalence of narrow angles in patients traditionally not thought to be at risk for angle closure glaucoma based on their refractive status. Our findings stress the importance of screening all patients for narrow angles regardless of refractive status or axial length.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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