Abstract
Abstract: :
Purpose: Fundus–controlled perimetry is useful in the assessment of the macular function. Aim of this study was to determine and quantify the influence of different parameter settings on perimetric results in fundus–controlled perimetry obtained with the MP1 Microperimeter. Methods: In 60 healthy eyes of 30 volunteers microperimetry was performed with the MP1 Micro Perimeter (Nidek Inc., Italy) using two different settings for stimulus duration and fixation object in random order. Stimulus presentation time was set to 100 ms in one eye and to 200 ms in the other eye. Either a black or a red cross served as fixation object. A rectangular 3–degree grid with 70 stimulus locations covering an area of 27 x18 degrees and a 4–2–1–staircase strategy was used in both settings. For each test point location light sensitivity threshold values were analyzed and compared intraindividually between both eyes. Fixation stability was assessed by evaluating the deviation from the mean fixation point during microperimetry. Results: Light sensitivity threshold values between the two settings varied according to the chosen stimulus presentation time. For a stimulus duration of 200 ms the mean light sensitivity (18.2 ± 0.5 dB) was significantly higher than for the 100 ms stimulus duration (16.1 ± 0.6 dB). Fixation stability employing a red cross as fixation object was superior to the use of a black cross. While the eyes fixating a red cross showed a stable fixation in 94%, only 70,6% of the eyes looking at a black cross had a stable fixation. Conclusion: Light sensitivity values in microperimetry with the MP1 depend highly on the choice of parameter settings. Reduction of the stimulus presentation time from 200 ms to 100 ms leads to a decrease of light sensitivity threshold values of about 2 dB. A red and well visible fixation object can augment the fixation stability in comparison to a black fixation object. The choice of parameter settings can influence microperimetric results and should therefore be carefully selected prior to examination.
Keywords: perimetry • macula/fovea • visual fields