Structural Grading of Foveal Hypoplasia Using Spectral-Domain ...

Figure 2. A, Optical coherence tomography scan showing a normal fovea with description of the normal foveal elements. Optical coherence tomography
scans showing the spectrum of foveal hypoplasia seen in various conditions, including: (B, C) albinism, (D, E) associated with PAX6 mutations, (F, G)
isolated cases, and (H, I) an atypical form of foveal hypoplasia seen in achromatopsia. A hyporeflective zone (cavitation) is also seen (I) that is a sign
of cone photoreceptor degeneration. Both foveal hypoplasia and fovea plana were seen in all disorders except the achromatopsia, which results in an
atypical form of foveal hypoplasia with a shallower pit, incursion of the plexiform layers, and disruption of the inner segment (IS)/outer segment (OS)
junction. INL inner nuclear layer; NFL nerve fiber layer; ONL outer nuclear layer.
morphologic OCT scan, and (3) it can be applied to most
disorders associated with foveal hypoplasia. The study also
showed that achromatopsia can be associated with foveal
hypoplasia, although it is associated with atypical features
such as IS/OS disruption and ONL thinning, which are signs
of photoreceptor degeneration, reduced retinal thickness
(RT), and a deeper foveal pit in comparison with the typical
forms of foveal hypoplasia.
From a developmental perspective, each grade suggests
developmental arrest of the 3 key events to varying degrees,
as shown in Figure 1. All patients with foveal hypoplasia in
this study had incursion of the plexiform layer posterior to
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Ophthalmology Volume 118, Number 8, August 2011
the foveola, suggesting that pit formation was incomplete in
all patients. A partial displacement of the inner retinal layers
results in a rudimentary pit, as encountered with grade 1
foveal hypoplasia and atypical foveal hypoplasia. This process
has failed to occur in grades 2, 3, and 4 of foveal
hypoplasia. Lengthening of the OS is a sign of cone photoreceptor
specialization, and this occurs to some extent in
grades 1 and 2, but not grades 3 and 4. Lengthening of the
OS can occur in the absence of a foveal pit, as seen in grade
2 foveal hypoplasia, and also as suggested by Marmor et al. 7
However, no cases where a foveal pit was present with no
OS lengthening (i.e., all patients with a foveal pit had OS