Abstract
Purpose: :
to evaluate the fixation stability in patients with RP and cystoid macular oedema (CMO) by microperimetry (MP1).
Methods: :
Twenty patients (40 eyes), 6 male and 14 female, mean age 49 years (range 27–71y.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), HFA (Humphrey 10–2 program, Goldmann stimuli, Sita–Standard strategy on 68 points ), acuity visual exam, fluorangiography (FAG), ocular coherence tomography (OCT) and retinography. Fixation stability has been evaluated with MP–1 considering 2° and 4° around the fixation point and correlated to mean visual acuity and retinography image.
Furthermore for each eye the decibel value concerning four matching points has 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 HFA according to C. Springer et all (Ophthalmology May 2005).
Results: :
The mean fixation stability was 55% considering 2° and 82% considering 4° around the fixation points: 10 eyes stable, 7 eyes unstable and 23 eyes relatively unstable. The value of mean visual acuity was 0,67 (range 0,2–1,1). The mean difference between MP1 and HFA about retinal sensibility was 15,58 ±8 dB and it resulted statistically significative (P=0,044).
Conclusions: :
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 but more than 75% inside the 4° diameter circle, and unstable if less than 75% of the fixation points are inside the 4° diameter circle. The mean fixation stability was 55% considering 2° and 82% considering 4° around the fixation points: 10 eyes stable, 7 eyes unstable and 23 eyes relatively unstable. There was an evident shift of fixation to preferential retinal locus (PRL) in 10 eyes with visual acuity 0.2. MP1 enabled a highly sensitive topographic monitoring of retinal function, showing central or pericentral fixation related to scotoma, visual acuity and the retinal alterations (retinography MP1, FAG and OCT).
Keywords: macula/fovea • perimetry • retinal degenerations: hereditary