Structure-functional correlation using adaptive optics, OCT, and microperimetry in a case of occult macular dystrophy

Abstract

We report retinal functional and structural changes of a 40-year-old man diagnosed with occult macular dystrophy. Comprehensive ophthalmological evaluation was performed, followed by spectral-domain optical coherence tomography (SD-OC - Heidelberg) and image acquisition using an adaptive optics (AO) camera (RTX1, Imagine Eyes) for photoreceptor density analysis. Functional tests included full-field ERG (ERG) and multifocal electroretinography (mfERG) (Diagnosys, LLC) and microperimetry with scanning laser ophthalmoscope (SLO) fixation controlled (MAIA, CenterVUE). OCT revealed a line of discontinuity corresponding to cone outer-segment photoreceptors associated with a loss of cone density, highlighted by a dark blue spot on the AO co ne-density map on the fovea in both eyes. Loss of central sensitivity was revealed using microperimetry; ERG was within the normal range, although the mfERG showed a reduced central response amplitude.

Fixation behavior in macular dystrophy assessed by microperimetry

“…Three case reports of occult macular dystrophy demonstrated that microperimetry revealed loss of sensitivity at the fovea [34–36], while one case preserved central fixation [34], another showed relatively unstable fixation [35], and the third exhibited unstable fixation with an infero-nasal PRL [36]. In eyes with Stargardt disease, a dense central scotoma causes fixation shift and PRL eccentricity correlates negatively with fixation stability [29, 30].…”

“…With regard to fixation stability, it is stable when the fixation point does not shift and is unstable in eyes with shifting fixation [ 29 ]; further, unstable fixation is strongly associated with poor visual acuity [ 32 , 33 ]. Three case reports of occult macular dystrophy demonstrated that microperimetry revealed loss of sensitivity at the fovea [ 34 – 36 ], while one case preserved central fixation [ 34 ], another showed relatively unstable fixation [ 35 ], and the third exhibited unstable fixation with an infero-nasal PRL [ 36 ]. In eyes with Stargardt disease, a dense central scotoma causes fixation shift and PRL eccentricity correlates negatively with fixation stability [ 29 , 30 ].…”

Adaptive optics imaging in the most common inherited retinal degenerations

“…The AO studies of patients with occult macular dystrophy (OMD) show regions of loss of photoreceptors, RPE visualization and lower cone density than in healthy eyes and a correlation of the morphological changes with the microperimetry [44][45][46].…”