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Page 180 Ma et al. J Transl Genet Genom 2022;6:179-203 https://dx.doi.org/10.20517/jtgg.2021.48

[3]
The global prevalence of high myopia was 4.0% before 2016 , and that of pathologic myopia was 0.9%-3.1%
[4]
before 2014 . The prevalence of high myopia presents an increasing trend in recent years. It is estimated
[3]
that 9.8% of the global population will have high myopia by 2050 . An even more astonishing fact is that
[5]
the prevalence of high myopia in children aged 6-19 years reached 73% in East Asia before 2019 . Visual
impairment caused by pathologic myopia will also increase correspondingly. Myopic retinopathy is the
second leading cause of blindness and low vision in Chinese adults . Both genetic and environmental
[6,7]
factors contribute to the development of myopia . Since the outbreak of COVID-19 in December 2019,
[8,9]
students have been confined to the house and attending class online. Students spent more time on near
work and less on outdoor activities. Home confinement has resulted in a significant myopic shift in students
[12]
aged 6-8 years [10,11] . As Bullimore et al. stated, even with a one diopter increase in myopia, the prevalence
of myopic maculopathy would increase by 67%.

Because many patients with high myopia face the risk of blindness, treatments are urgently required to cease
visual loss and preserve the remaining visual function. This manuscript reviews myopic maculopathy with
an emphasis on current treatment modalities and conceptualized stem cell-based therapy.

Introduction of myopic maculopathy
Myopic maculopathy, also named myopic macular degeneration and myopic retinopathy, is defined as the
condition comprising diffuse or patchy macular atrophy with or without lacquer cracks, choroidal
neovascularization (CNV), and Fuchs’ spot . Myopic maculopathy is seen in 22.9% of high myopes aged 7-
[1]
[13]
70 years . The severity of myopic maculopathy increases with older age and longer axial length (AL) [13-15] .
Myopic maculopathy is not common in young patients. In patients around 20 years, myopic maculopathy is
[16]
present in 8.3% . In patients younger than 40 years, it is present in 18.7% . In patients aged 40-70 years,
[13]
[13]
the prevalence of myopic maculopathy increases to 58.3% .
The meta-analysis for pathologic myopia (META-PM) classification proposed by an international panel of
[17]
myopia researchers in 2015 is used in pathologic myopia classification . META-PM classification is based
on photography [Figure 1]. There are five categories of myopic maculopathy [Table 1]: no myopic retinal
degenerative lesion (Category 0) [Figure 1A]; tessellated fundus (Category 1) [Figure 1B]; diffuse
chorioretinal atrophy (Category 2) [Figure 1C]; patchy chorioretinal atrophy (Category 3) [Figure 1D]; and
macular atrophy (Category 4) [Figure 1E]. The categories indicate progressed chorioretinal atrophy.
Additionally, three plus signs for lacquer cracks, myopic CNV, and Fuchs’ spot can be applied to any
category. The plus signs indicate three statuses of myopic CNV (mCNV). Lacquer cracks are the breaks of
RPE [Figure 1F], Bruch’s membrane (BM), and choriocapillaris. They provide an entrance of CNV to grow
into subretinal space [Figure 1G]. Fuchs’ spot is the scar of mCNV with pigmentation [Figure 1H]. The
[17]
plus signs are lesions that could directly or potentially impair the central visual acuity. Among these three
plus signs, only mCNV requires clinical interventions.

This classification system provides ophthalmologists with a simplified and uniform system to categorize
myopic maculopathy by severity. The characteristic alternations in each category are presented in Figure 2.

Category 1: tessellated fundus
Tessellated fundus, or tigroid fundus, is the preliminary sign of myopia. It results from thinning of the
retina and increasing visibility of the deep choroidal vessels . The factors related to the cause of fundus
[16]
tessellation include hypoplasia of the retinal pigment epithelium (RPE), reduced filling of the
choriocapillaris, and increased pigmentation of the choroidal stroma . Tessellated fundus is not associated
[18]
with a decline in best-corrected visual acuity (BCVA) . Tessellated fundus can progress to the next
[17]