Abstract
Purpose: :
The purpose of this study is to examine the structural morphology and general function of cone photoreceptors within the central macula of a family afflicted with autosomal dominant retinitis pigmentosa (RP) caused by the rhodopsin mutation D190N.
Methods: :
The cone photoreceptor mosaics of three patients with RHO D190N dominantly inherited retinitis pigmentosa, case 1 (son, 11 yr.), case 2 (son, 16 yr.), and case 3 (father, 52 yr.), were examined by high-resolution images provided by adaptive optics-scanning laser ophthalmoscopy (AO-SLO) at various areas within the parafoveal hyperautofluorescent ring in their respective, degenerating retinas. AO-SLO data from the three RP patients were statistically matched to a normative database of healthy subjects within their respective age groups. Further comparative structural and functional measurements have been carried out by spectral-domain optical coherence tomography (SD-OCT), microperimetry-1 (MP1), and full-field electroretinography (ERG).
Results: :
All AO-SLO parameters in case 1, case 2, and case 3 show no significant differences (p ≥ 0.05) when compared to normative subjects. SD-OCT and MP1 showed intact IS/OS junctions and retinal pigment epithelia and normal visual acuity within the parafoveal hyperautofluorescent rings of each patient, respectively. Full-field ERG measurements in case 1 and case 2 identified normal cone function within the retina.
Conclusions: :
A high-resolution evaluation of the retinas of (pre)teen and adult RHO D190N RP patients within an immediate family by AO-SLO shows that cone photoreceptors within the parafoveal hyperautofluorescent ring are spatially and morphologically normal. Generalized cone function was also found to be normal as indicated by full-field ERG. The aggressive diminishment of the visual field in case 3 is represented by the constriction of the hyperautofluorescent ring; this finding is consistent with the progressive nature of autosomal dominant RP. Our findings conclude that cone photoreceptors within a 1.5mm diameter hyperautofluorescent ring in asymptomatic (pre)teen RP patients (case 1 and case 2) and a symptomatic RP adult (case 3) are morphologically and functionally normal. The application of AO-SLO, in conjunction with traditional diagnostic methods in ophthalmology, can uncover a valuable understanding of the clinical progression of RHO D190N autosomal dominant RP. Furthermore, early studies in young RP cases along with related, more advanced cases afflicted with the same pathological mutation can greatly advance knowledge regarding early therapeutic windows for intervention to delay or even prevent irreversible blindness in progressive diseases such as RP.
Keywords: retinal degenerations: hereditary • photoreceptors • imaging/image analysis: clinical