J Korean Ophthalmol Soc.  2013 Sep;54(9):1401-1406.

A Study for Effective Gaze Fixation Induction Methods in PC-Based Visual Field Testing

• Lee JH
• Lee BH
• Park HJ
• Choi JH
• You HC
• Kang JH

Abstract

PURPOSE
The present study explored novel methods in visual field tests that actively induce the gaze of the examinee to the fixation target in the center vision and compared their effectiveness.
METHODS
Four gaze induction methods (dot-on, dot-off, number-on, and number-off) were prepared by combining 2 types of fixation targets (dot and number) and 2 conditions of sound presence (on and off). The gaze induction methods were implemented to a PC-based visual field testing system and the 24-2 visual field testing protocol was administered to 14 participants without glaucoma. The performance of the gaze induction method was evaluated in terms of fixation error rate, target detection rate, and subjective satisfaction (7-point scale, 1 for least satisfied and 7 for most satisfied).
RESULTS
The fixation error rates of dot-on (5.7%) and number-on (6.4%) were relatively lower than the other methods; the target detection rates of the induction methods were very high (95-96%) without significant differences, and the subjective satisfaction levels of dot-on (5.7) and number-on (5.4) were significantly higher than the other methods.
CONCLUSIONS
In the present study we determined number-on as the preferred effective gaze induction method compared to the conventional dot-off method when fixation error rates and subjective satisfaction were considered.

Keyword

Gaze induction; Glaucoma; Visual field test

MeSH Terms

Glaucoma
Vision, Ocular
Visual Field Tests
Visual Fields

Figure

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  Figure 1. A prototype of PC-based visual field tester. (A) PC monitor (19 inch, Flatron L1940 plus, LG Electronics, Korea; pixel pitch = 0.294 mm) for presenting targets for testing a visual field. (B) visor for shielding outside lights, helping con-centration during test, selecting an eye to be tested and main-taining the distance between the eye and the monitor. (C) face support for maintaining the position of the eye and supporting comfortable posture. (D) input device for fixation target (1 or 2) confirmation. (E) input device for target detection.

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  Figure 2. The target locations of the visual field testing S/W for the right eye. The visual field forms 24˚ superiorly, in-feriorly, temporally, and 30˚ nasally. The location of a blind spot was 1° superiorly and 16° temporally from the fixation target positioned at the center of a visual field area. The total number of target locations is 56 (1 for the fixation target, 54 for visual field targets, and 1 for blind spot).

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  Figure 3. Experimental procedure. Four-step visual field testing is conducted: S1 = Introduction; S2 = Identification of the testing distance, alignment between the eye and the fix-ation target on the screen, and fixation of the face on the face support; S3 = Visual field testing randomly by 4 conditions (dot-on, dot-off, number-on, and number-off), 1 minute break among each condition; S4 = Evaluation of subjective sat-isfaction (7-point scale).

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  Figure 4. Results of visual field testing performance and subjective satisfaction. Dot-on condition: central target = dot and sound = on; dot-off condition: central target = dot and sound = off; number-on condition: central target = 1 or 2 and sound = on; number-off condition: central target = 1 or 2 and sound = off. (A) Fixation error rate (mean ± SE). (B) Subjective satisfaction by using 7-point scale (mean ± SE).

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  Figure 5. The rates of missing targets near the blind spots at the left eye (A) and right eye (B).

Reference

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