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S. Cavarretta, S. Putano, A. Segnalini, S. Lupo, E.M. Vingolo; Mapping of Central Visual Function by Micro Perimeter 1 in Patients With Retinitis Pigmentosa and Macular Oedema . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5664.
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© ARVO (1962-2015); The Authors (2016-present)
to evaluate and to correlate the different retinal sensibility and specificity in patients with RP and cystoid macular oedema (CMO) by microperimetry (MP1) and conventional automated static perimetry with Humphrey (HFA 10–2 program).
Twelve patients (24 eyes), 6 male and 6 female, mean age 46 years (range 37–52 y.o.) affected by RP have been selected, they presented cystoid macular oedema. Patients with diabetes, hypertension and other ocular pathologies have been excluded. All patients were subjected to MP1 (Humphrey 10–2 program, Goldmann III stimuli, 4–2–1 strategy on 68 points) and HFA (Humphrey 10–2 program, Goldmann stimuli, Sita–Standard strategy on 68 points ). For each eye the decibel values concerning four matching points have been recorded and calculated the mean value. This value has been compared with the mean value of the other eye and with the one found with the conventional perimetry (Humphrey 10–2) according to C. Springer et all (Ophthalmology May 2005).
Furthermore fixation stability has been evaluated with MP–1 considering 2° around the fixation point.
Retinal mean sensitivity considering four central matching points was 7,5 ± 5 dB (range 0,5–13) in the MP1, and 23,58 ± 4 dB (range 9– 26,5) in HFA. The mean difference between both examination was 15,58 ±8 dB and it resulted statistically significative (P=0,044). The mean fixation stability was 55% considering 2° around the fixation points: 6 eyes stable, 4 eyes unstable and 14 eyes relatively unstable.
The results show a higher retinal sensibility for the four central points evaluated with MP1 than HFA according to the visual acuity, the fixation and the lesions found with the retinography. There is a high difference between the two systems because 2 decibel scales are defined by different starting points. In MPI a response elicited from a receptive field stimulated with a high level luminescence can influence more retinal cells out of the same receptive field showing spatial addiction.
Fixation is regarded as stable if more than 75% of the fixation points are inside the 2° diameter circle, as relatively unstable if less than 75% are inside the 2° diameter circle, and unstable if less than 75% of the fixation points are inside the 4° diameter circle.
This study underlines a higher specificity of MPI than HFA to detect macular retinal alteration: in MP1 the scotoma result larger and it is possible to correlate it to the stability of fixation, visual acuity and ophthalmoscope image easily.
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