Abstract
Purpose: :
North Carolina macular dystrophy (NCMD) is one of the rarer forms of juvenile-onset macular dystrophies. One-third of these patients initially present as having a coloboma-like macular lesion with good retinal function. The aim of this study was to describe the structural findings, as obtained by spectral-domain optical coherence tomography (SD-OCT) and correlate with the retinal function, as measured by visual acuity, visual fields and microperimetry (MP-1) in two young siblings with NCMD.
Methods: :
The proband, a 16-year old girl and a 14-year old brother underwent a complete ophthalmological examination and were clinically diagnosed to have NCMD. Visual acuity, visual field testing, SD-OCT (Spectralis), fundus autofluorescence (FAF), color fundus photography and microperimetry were performed on both siblings.
Results: :
Both siblings with NCMD had a normal-appearing anterior segment. However, the 16-year old sibling showed a large, bilateral, coloboma-like macular lesion whereas the 14-year old brother showed a relatively smaller macular lesion with no evidence of a coloboma. This was consistent with slightly reduced visual acuity, retinal pigment epithelium (RPE) changes with coloboma-like structure on SD-OCT and hypoautofluorescent areas on FAF in the older sister as compared to normal visual acuity, milder RPE changes on SD-OCT and normal FAF in the younger brother. The retinal functional changes were also consistent with structural changes - MP-1 showed increased thresholds in the older sister with normal thresholds in the younger brother. It was interesting to note that although the macular lesions were large and there was RPE involvement, the photoreceptor cell layer looked intact on SD-OCT.
Conclusions: :
Well-preserved retinal function as measured by microperimetry correlates with the relatively spared photoreceptor layers as shown by Spectralis SD-OCT and provides an insight into the pathophysiology of a rare condition like North Carolina macular dystrophy.
Keywords: retinal degenerations: hereditary • macula/fovea