New five categories of MMD

Interesting new look at myopic macular degeneration. Click here to read more. 

Myopic Macular Degeneration (MMD)

MMD is also known as myopic maculopathy and myopic choroidal neovascularisation but to help with public awareness, the term MMD is preferred because of the widespread use of age related macular degeneration being the age related form while MMD is the myopic related form. 

MMD is the most common cause of vision impairment in patients with myopia with 10 per cent of those with pathologic myopia developing myopic macular degeneration (via choroidal neovascularisation (CNV)). 

Signs of MMD include chorioretinal atrophy, patchy chorioretinal atrophy, lacquer cracks, choroidal neovascularisation (CNV) and CNV-related macular atrophy in the presence of higher levels of myopia. 

Early signs of a tessellated fundus are likely to develop into diffuse atrophy or lacquer cracks, patchy atrophy or choroidal neovascularisation and finally into MMD. Until recently this condition was rarely separated from age related macular degeneration and in official WHO reports it is classified in the “other” category.

In response to the need to recognise and record cases of MMD, Ohno-Matsui et al.19in 2015 developed and recommended a five category grading scale. They noted that the definition of MMD had not changed since it was first identified in 1970 nor was there a generally accepted grading scale. 

The scale developed by Ohno-Matsui et al. has, “five categories of myopic maculopathy including “no myopic retinal degenerative lesion” (category 0), “tessellated fundus” (category one), “diffuse chorioretinal atrophy” (category two), “patchy chorioretinal atrophy” (category three), and “macular atrophy” (category four).”

They also identified lacquer cracks, myopic choroidal neovascularisation and Fuchs spots as “plus” lesions to supplement their categories.19 Adoption of such a system will allow for comparisons between studies to be made more accurately and enable better recording and reporting of this blinding condition.

The public already has an awareness of the term “age related macular degeneration” and so the concept of myopia macular degeneration is likely to be understood as macular degeneration that happens in people with higher amounts of myopia. 

Second, there is also a significant distinguishing feature of myopic macular degeneration; as Ohno-Matsui points out, it often affects individuals in their productive years, while age related macular degeneration usually affects individuals who are no longer in the workforce. Thus the economic burden is likely to be significantly higher for MMD than for AMD. In addition to the treatment costs and cost of care there will also be a loss of productivity.