Purpose: Myopia and high myopia has markedly increased in importance due to the myopic shift taking place in the young generation of metropolitan societies in Asia. Myopia and high myopia leads to characteristic changes in the macula and the optic nerve head. The purpose of this study was to re-address these particularities in enucleated human eyes by light microscopy. 

Methods: The histomorphometric study included 65 human globes (axial length:21-37mm).  On anterior-posterior histological sections, we measured the distance Bruch′s membrane end (BME)-optic nerve margin (“Gamma zone”), BME-retinal pigment epithelium (RPE) (“Beta zone”), BME-beginning of non-occluded choriocapillaris, and BME-beginning of photoreceptor layer.  “Delta zone” was defined as part of gamma zone in which blood vessels of at least 50μm diameter were not present over a length of >300μm. 

Results.  Beta zone (mean length:0.34±0.52mm) was significantly (P=0.046) larger in the glaucoma group than in the non-glaucomatous group.  It was not significantly (P=0.28) associated with axial length.  Beta zone was significantly (P=0.03) larger than the region with occluded choriocapillaris.  Gamma zone (mean length:0.63±1.15mm) was associated with axial length (P<0.001;r2=0.72) with an increase starting at an axial length of 26.5mm.  It was not significantly (P=0.24) associated with glaucomatous optic neuropathy.  Delta zone (present only in eyes with axial length of ≥27mm) was associated with axial length (P=0.04) but not with glaucoma (P=0.18).  In the macula of highly myopic eyes, some areas showed a rupture and defect in Bruch′s membrane with a complete lack of RPOE cells and choriocapillaris.

Conclusions.  Parapapillary gamma zone (peripapillary sclera without overlying choroid, Bruch′s membrane and deep retinal layers) was related with axial globe elongation and was independent of glaucoma.  Beta zone (Bruch′s membrane without RPE) was correlated with glaucoma but not with globe elongation.  Since the region with occluded choriocapillaris was smaller than beta zone, complete loss of RPE may have occurred before complete choriocapillaris closure.  Delta zone (no blood vessels >50μm diameter within gamma zone) was present only in highly axially elongated globes.  Myopic maculopathy can be characterized by a defect in Bruch′s membrane with a lack of adjacent tissues. These histologic findings will be discussed in association with clinical and epidemiological data.