Grosor coroideo en la retinosis pigmentaria

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The choroid is involved in ocular diseases, as an integral constituent in the functioning of the eye. Recently, different author have observed that choroidal thickness is altered in different chorioretinal diseases; in addition, it has been documented a decreased choroidal blood flow in Retinitis Pigmentosa. Therefore we have designed this study to analyze the choroidal thickness in this chorioretinal dystrophy. The aim of the present study were to measure choroidal thickness by using optical coherence tomography (Cirrus-HD-OCT®) in patients with Retinitis Pigmentosa and in healthy subjects; and to compare both groups. Secondarily, we analyzed the possible the functional value of choroidal thickness in patients with Retinitis Pigmentosa. 41 patients with Retinitis Pigmentosa and 32 healthy subjects were included. The inclusion criteria for the Retinitis Pigmentosa group were: Caucasian subjects older than 18 years; typical Retinitis Pigmentosa fundus appearance; electrophysiological findings suggestive of Retinitis Pigmentosa. A control group with healthy Caucasian subjects was recruited. The exclusion criteria were: patients with syndromic Retinitis Pigmentosa forms; control subjects and patients with: refractive error over +/-6 spherical or +/-2 cylindrical diopters; history of other ophthalmological diseases, and/or invisible scleral-choroidal junction. Finally, 75 eyes of 40 patients (47.24 ± 8.11 years) and 54 eyes of 31 healthy controls (45.85 ± 8.99 years) were analyzed. Choroidal thickness was measured by Cirrus-HD-OCT®. Nine measurements were taken from 2000 µm nasally to 2000 µm temporally, every 500µm, and the subfoveolar point was the central measurement point. The choroidal thickness value for each point was the average result of three different measurements. In addition, each Retinitis Pigmentosa patient underwent a complete ophthalmologist exploration and the next values were collected: best corrected visual acuity, visual field values (low vision index, preserved visual field degrees), autofluorescence measurements (hyperautofluorescence macular ring diameter and preserved autofluorescence diameter) and the IS/OS band length. Finally, statistical analysis included t-Student test for independent samples, and Pearson correlation test, using SPSS 17.0 software. Choroidal thickness statistically reduced at each measurement point in Retinitis Pigmentosa patients (p<0.001). The choroidal pattern distribution was also analyzed to investigate possible differences between control subjects and Retinitis Pigmentosa patients. A progressive thinning pattern toward the nasal sector was observed in both groups. In fact, the choroidal distribution pattern differed statistically only at the 2000 µm measurement point nasally (p<0.001; one-way ANOVA; a post-hoc Scheffe test). Furthermore, macular choroidal thickness was positively correlated with better anatomical and functional finding in Retinitis Pigmentosa patients: macular choroidal thickness was statistically correlated with visual acuity [p<0.05, except for subfoveolar point where the correlation was not statistical (p=0.13)], preserved autofluorescence diameter (p<0.01), visual field values (p<0.05) and IS/OS band length (p<0.05). Age and choroidal thickness were negatively correlated in both groups (control group p<0.01, Retinitis Pigmentosa patients p<0.05). The present study suggests that choroidal thickness decreases in Retinitis Pigmentosa patients as seen by Cirrus-HD-OCT®. In addition, this study suggests that thicker macular choroidal thickness is correlated with better visual function in Retinitis Pigmentosa patients. Thus, choroidal thickness may be a new objective anatomical-functional measurement in the evaluation of this chorioretinal dystrophy.
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