Abstract
Purpose: :
Occult macular dystrophy (OMD) is a hereditary disease characterized by an essentially normal fundus and fluorescein angiography but progressive decline of visual acuity in both eyes. These patients have normal full-field electroretinograms (ERGs) but severely reduced focal macular ERGs. The responsible lesion of OMD remains to be elucidated. We experienced two patients with OMD who are a mother and her daughter. We report the tomographic features of the retina using spectral domain optical coherence tomography (SD-OCT).Cases:Case 1 is a 42 year-old woman. Her best corrected visual acuity (BCVA) was (0.1) in both eyes. She had a symptom of gradually declined central vision in both eyes at childhood. Her father was diagnosed as retinitis pigmentosa. She had primary open angle glaucoma with Bjerrm scotoma. Her intraocular pressure was 23 mmHg in OD and 19 mmHg in OS respectively after 2 years discontinuity of glaucoma treatment. Color fundus, fluorescein angiography (FAG) showed normal but indocyanine green angiography (ICG-A) exhibited hypofluorescence in the macula. Although full field ERG was normal, multifocal ERG (mfERG) revealed decreased macular response in both eyes. SD-OCT showed normal layered structure of the retina including the junction between photoreceptor inner and outer segment (IS/OS line) except the macular area. However IS/OS line was poorly defined and outer nuclear layer was attenuated in the macular area with 1,000 micron diameter.Case 2 is a 14-year old daughter of the case 1. Her BCVA was 0.2 in right and 0.3 in left eye. Her fundus shows slightly dark color. FAG was normal but ICG-A showed hypofluorescence at the fovea in both eyes. Although full-field ERG was normal mfERG showed severely decreased response at the fovea. SD-OCT revealed blurred IS/OS line at the fovea with 500 micron diameter.
Conclusions: :
Blurred IS/OS line in the macula with corresponding decreased response in mfERG were main feature of OMD. Low grade degeneration of photoreceptor outer segment of cone cells appeared responsible lesion of OMD.
Keywords: macula/fovea • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • photoreceptors