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Proposed Standards for Visual Acuity and IOP

Glaucoma Publications Interest Group November 2000

Richard P. Mills

1. Introduction

   1. The standard is aspirational

   2. Manuscripts that adhere to the standard do not need to explain the rationale for the methodology

   3. Alternative methods may be used, but an explanation of reasons for using this alternative method should be included in the text.

2. Visual acuity

   1. Test method: EDTRS chart with standard illumination. Reported as the number of correct letters read. If the Snellen chart is used, LogMar conversion should be used for reporting.

   2. Number of repetitions: one is sufficient.

   3. Protocol: ETDRS technique; if the Snellen chart is used, masking of the visual acuity examiner is preferable.

   4. When: Standardized intervals (n ≥ 2). If 'final' visual acuity is reported, this should be after a minimum interval in a stable period.

3. Intraocular pressure

   1. Method: Goldmann applanation.

   2. Number of repetitions: two if within 2 mmHg, using mean; otherwise three, using the median.

   3. Protocol: masked, rounded off to the nearest whole number, dilute the fluorescein solution.

   4. When: standardized intervals (n ≥ 2), at a similar time of day for each visit. If 'final' IOP is reported, this should be after a minimum interval in a stable period.

   5. IOP data format: mean, median, and range are desirable. IOP change may be reported as change in mmHg or as percentage change.

   6. Modifying factors:

      1. If the absolute (rather than the relative) level of IOP is important, then central corneal thickness should be reported.

      2. Axial length, tissue elasticity, patient demographics, and technique variances.