Purchase this article with an account.
Marco U Morales, Gianfrancesco M Villani, Fabio Turra, Chiara Borgogno; Dynamic Multifixation Target for Microperimetry to Use in Patients With Large Central Scotoma. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4139.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The microperimetry MAIA (Centervue; Padova, Italy) has a standard LED fixation target (FT) consisting of a small red circle of 0.76° diameter size. However, subjects with low-vision due to large central scotoma and unstable fixation may find it difficult to see. The current study explored the use of an alternative eccentric FT assembly in such patients.
An array of 20 LED cross-shaped eccentric FTs located around the standard central FT was designed. Such eccentric FTs are distributed on a 5 by 5 grid without all four corners. The grid horizontal and vertical spacing is 2.4°. The center of the grid is the standard central FT. Each cross FTs are sized 1.2° by 1.2°. Ten patients with central geographic atrophy secondary to dry AMD performed the MAIA examination at the CRIM Low Vision Center in Verona, Italy. First, they were asked to fixate the standard central FT. If they failed, the operator selected an eccentric FT located outside of the macular lesion according to the SLO image. Once the target was detected, the operator switched the FT to an adjacent one to guide the vision in the direction of the central FT. The examination started when the patient was either able to perceive the central FT or with the last perceived eccentric FT. Visual acuity (VA), scotoma size (SS), fixation stability (FS) and the ability to see the target for the examination was recorded.
10 patients with CGA and unstable fixation (mean age = 71.3, mean VA=0.8 LogMAR, mean SS=9.5° and mean FS=33%) performed the MAIA examination. Four patients (40%) were able to find easily the standard central FT. Their mean VA was 0,76 LogMAR, mean SS and mean FS were 7.2° and 31% respectively. Five patients (50%) (mean VA=0.88 LogMAR, mean SS=10.2° and mean FS=40%) were initially unable to detect the central FT, but successfully did it after being directed by the sequential lighting of eccentric FTs. One patient (10%) with VA=1.2 LogMAR, SS=15°, and FS=5% never saw the small central FT, although the microperimetry examination was performed while fixating an eccentric FT adjacent to the central one.
Patients with central vision loss may have difficulties in detecting the standard MAIA small FT. With the proposed dynamic multi-fixation target, patients with large central scotomas and unstable fixation were able to perform the MAIA microperimetry examination.
This PDF is available to Subscribers Only