Relationship of visual field sensitivity in central 10-degrees to thickness of different retinal layers in eyes of patients with retinitis pigmentosa

Abstract

Purpose : Retinitis Pigmentosa (RP) is a hereditary retinal disease characterized by a progressive constriction of the visual field due to photoreceptor degeneration. The aim of this study was to determine the relationship between the sensitivity of the retina in the central 10-degrees and the thickness of the different retinal layers.

Methods : We reviewed the medical records of 25 eyes of 25 RP patients who had been followed at the Nagoya University Hospital. All of these patients had been examined by Humphrey Field Analyzer 10-2 program (HFA10-2) and spectral-domain optical coherence tomography (SD OCT) on the same day. The SD-OCT images of 20 normal subjects were used as controls. The thicknesses of the outer segment (OS), outer nuclear layer (ONL), and inner nuclear layer (INL) were measured at 1, 3, 5, 7, and 9 degrees from the fovea in RP patients and controls. The thicknesses of OS, ONL, and INL of the RP patients were divided by the average thicknesses of the OS, ONL, and INL of the controls at the same locations to calculate the relative thickness. The relationship between the relative thickness of each layer and the total deviation (TD) of the HFA 10-2 of the corresponding location was determined. We performed the analysis combining all the locations. The Pearson coefficient correlation was used for comparisons between the reduction of visual field sensitivity and the relative retinal thickness.

Results : The average thicknesses of the OS, ONL, and INL of all the points were 26.5±18.0 μm, 49.1±32.4 μm, and 34.0±11.0 μm in the RP patients and 41.7±5.95 μm, 65.4±18.2 μm, and 31.7±11.0 μm in the controls (P<0.01, P<0.01 and P=0.02, respectively). The OS and ONL were significantly thinner in the RP patients while the INL was significantly thinner in the controls. The TD was significantly correlated with the relative OS thickness (r²=0.613, P<0.01), and relative ONL thickness (r²=0.605, P<0.01), but not with the relative INL thickness (r²=0.003, P=0.198).

Conclusions : In RP patients, the OS and ONL thicknesses decrease with a reduction in the visual field sensitivity. Although the INL was thicker in RP patients than controls, it was not significantly correlated with the visual function. The results of the HFA 10-2 and SD OCT examinations are useful in understanding the relationships between the function and structure of the eyes of RP patients.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.