New approach for the glaucoma detection with pupil perimetry

Ken Asakawa¹, Nobuyuki Shoji^1,2, Hitoshi Ishikawa^1,2, Kimiya Shimizu³

¹Department of Ophthalmology and Visual Science, Kitasato University Graduate School, Doctors Program of Medical Science, ²Department of Orthoptics and Visual Science, Kitasato University, School of Allied Health Science, ³Department of Ophthalmology, Kitasato University, School of Medicine

Objective: To calculate the pattern deviation for identifying abnormal points of pupil perimetry, and also to evaluate the grayscale display for distinguishing glaucomatous pupil field loss (abnormal test points) from normal pupil field (normal test points).

Methods: Fourteen patients ranging in age from 51 to 80 years, who had normal-tension glaucoma (6 eyes) and primary open-angle glaucoma (8 eyes) were tested. Pupil perimetry (Kowa & Hamamatsu, Japan) was used to objectively measure the visual field. Also, to obtain a subjective visual field, the analysis was performed with a Humphrey Field Analyzer (30-2, Full threshold program, Carl Zeiss Meditec, Dublin). Of the 76 test points, the 22 surrounding points and the 3 points corresponding to the blind spot are excluded; and among the remaining 51 points, the 85th percentile value of pupil perimetry was calculated. The abnormal and normal test points were recorded, and the amount of positive or negative deviation of each test point from the normal median value for the corresponding test points was determined. We also used this technique to identify the value for distinguishing glaucomatous pupil field loss from the normal pupil field.

Results: This study could be improved by calculating the sensitivity and specificity of a certain cut-off value between the normative data and the glaucoma patients. The value for identifying both abnormal and normal test points was a negative deviation of –4. Based on these results, pupil perimetry gray scales were determined: white (< –3), 25% gray (from –4 to –8), 50% gray (from –9 to –13), 75% gray (from –14 to –18) and black (> –19). Glaucomatous pupil field losses were generally distinguished from the normal pupil field by use of a gray scale.

Conclusion: Our studies demonstrated that, when a deviation of > –4 was regarded as an abnormal value, the detection of pupil perimetry exhibited improvement in glaucoma patients.

Keywords: pupil perimetry, percentage pupil constriction, glaucoma, pattern deviation, gray scale