Once a neurological problem has, therefore, been ruled out, the disorders reduced visual acuity without visible fundus abnormalities may be misdiagnosed as optic neuritis, dominant optic atrophy, amblyopia, or nonorganic visual disorder.The combination of weak amplitudes in the mfERG with no visible fundus abnormalities then rules out other explanations. For example, OMD presents negative for a full-field ERG while retinitis pigmentosa presents abnormal. Prognosis
Since the abnormality is not in the eye lens, the disease is not correctable with eyeglasses. Vision becomes dimmer over the course of years as the macula loses function. Eventually the patient may become legally blind. The peripheral vision field is preserved. In other words, OMD does not cause total blindness, due to the concentration of the degradation at the cone-rich (color-sensitive) region of the retina. No treatment is known to slow the progression. The speed of progression varies by case — even between donor and recipient of the mutation — and can last for 10 to 30 years. Future research
Because of the rarity of OMD, no clinical trials are in the pipeline as of January 2019. However, mutations in RP1L1 might play a role in retinitis pigmentosa (RP), raising hope for a spillover effect for OMD patients should an RP1L1-related treatment be developed for RP. Given the possible relation between ABCA4 and OMD, progress with Stargardt disease via gene therapy might have a spillover effect for OMD patients as well. Adeno-associated viral (AAV) vectors have been particularly successful in gene therapy of eyes and muscles.
One study suggests that OMD arises because of two mutations arising simultaneously, one in RP1L1 and another in ABCA4.OMD is generally believed to be autosomal dominant, meaning that if you get the abnormal gene from only one parent, you can get the disease. However, this does not always seem to be the case.OMD differentiates from Stargardt macular dystrophy in which gene is mutated (RP1L1 instead of ABCA4), the process of OMD isnt a buildup of toxic lipofuscin, and Stargardt is regressive. Physiology
The connection between these mutations and OMD is unclear, but cone density is significantly lower in patients with OMD compared to the general population. Use of adaptive optics to obtain high-resolution retinal images reveal abnormal changes in patients with OMD, including thinning of the foveal thickness and the outer nuclear layer and disruption of the IS/OS line and COST line. Diagnosis
OMD returns negative results for a funduscopic inspection, fluorescein angiogram, and full-field electroretinogram (ERG), for both rod and cone components. The key to diagnosing this disorder is the multifocal ERG (mfERG), providing a single procedure for diagnosis. Onset is known to range from age 6 to 81, with about half of onsets occurring after age 65. Differential diagnosis
A visual field test can differentiate between whether the reduced visual acuity is centered on the optic nerve or the fundus.