Abstract
Abstract: :
Purpose: An older instrument, the Canon Fundus Camera–Perimeter CPP–1 was compared with the new Nidek Micro–Perimeter MP–1. The CPP–1 combines a kinetic and static perimeter with a fundus camera. Patho–anatomical features and measured visual functions are directly related at defined retinal loci. The CPP–1 has a background field of 10 asb and a Goldmann I or IV test spot (luminance settings up to 1000 asb). Infrared (IR) is used to view the retina during perimetric testing; needle incisions are made in a parallel record of kinetic threshold locations or static threshold test loci. Data are overlaid on the color fundus photograph. The MP–1 utilizes automated and non–automated static perimetric tests, and automatic fixation control. The background field is set at 4 asb, and a Goldmann incremental test field can be altered up to 400 asb in 0.1 Log Unit steps. Static thresholds are determined. IR viewing is used for perimetric tests, and test results are digitally super–imposed upon a color photo. Fixations and fixation stability are assessed. Methods: For comparisons, only static perimetric testing and a Goldmann I target were used. Background luminances were set to manufacturers’ specs. Trained student subjects, with low and high myopias, were tested about and upon their optic nerve heads – see ARVO '03 paper #2776. 13 subjects were used. With CPP–1 we compared subject data from '02 and '03. There was interest in vision of myopes with retinal and choroidal nasal over–rides onto the optic nerve head (myopic nasal super–traction of the disc). Results and Conclusions: The CPP–1 and MP–1 both functioned effectively; the MP–1 instrument provided rapid examination. The lower luminance photo–flash of the MP–1 was advantageous in terms of patient comfort and speed of the exam. MP–1 automated functions proved valuable, e.g., fixation measurement and control, eye–movement stabilization, etc. The virtue of fundus camera–perimeters lies in correlation of anatomy and function at examiner–defined loci. Screening perimetric routines are not as valuable for this, but there are MP–1 programs which meet such requirements. In some eyes, when using MP–1, we found false positives when testing on discs. Some MP–1 test data obtained in IR and superimposed on color photographs were out of alignment by ca 2 or 3 degrees. If one retains perimetric data on the original IR display, the problem is resolved. Where retinal sensitivity was meaningfully reduced (as on myopic discs with nasal retinal over–rides), the higher luminance of CPP–1 proved superior for assessing vision, but, could result in brief saturation responses (3 to 4 min).
Keywords: myopia • photoreceptors: visual performance • visual fields