Distribution of macular ganglion cell layer thickness in foveal hypoplasia: A new diagnostic criterion for ocular albinism

Abstract

Background/AimsTo analyse the distribution of macular ganglion cell layer thickness (GCLT) in patients with foveal hypoplasia (FH) with or without albinism to obtain new insights into visual pathway anomalies in albinos.MethodsPatients with FH who presented at our institution between 2013 and 2018 were retrospectively drawn for analysis. Mean GCLT was calculated after automated segmentation of spectral domain-optical coherence tomography (SD-OCT) scans. Patients with FH due to albinism (n = 13, termed ‘albinism FH’) or other kinds (n = 10, termed ‘non-albinism FH’) were compared with control subjects (n = 15). The areas: fovea (central), parafovea (nasal I, temporal I) and perifovea (nasal II, temporal II) along the horizontal meridian were of particular interest. Primary endpoints of this study were the ratios (GCLT-I- and GCLT-II-Quotient) between the GCLT measured in the temporal I or II and nasal I or II areas.ResultsThere was a significant difference between the GCLT-I-Quotient of healthy controls and albinism FH (p<0.001), as well as between non-albinism FH and albinism FH (p = 0.004). GCLT-II-Quotient showed significant differences between healthy controls and albinism FH (p<0.001) and between non-albinism FH and albinism FH (p = 0.006). The best measure for distinguishing between non-albinism FH and albinism FH was the calculation of GCLT-II-Quotient (area temporal II divided by area nasal II), indicating albinism at a cut-off of <0.7169. The estimated specificity and sensitivity for this cut-off were 84.6% and 100.0%, respectively. The estimated area under the curve (AUC) was 0.892 [95%CI: 0.743–1.000, p = 0.002].ConclusionMacular GCLT-distribution showed a characteristic temporal to central shift in patients with FH due to albinism. Calculation of the GCLT-II-Quotient at a cut-off of <0.7169 presents a new diagnostic criterion for identification of ocular albinism.

Assessing Ganglion Cell Layer Topography in Human Albinism Using Optical Coherence Tomography

“…Foveal hypoplasia is characteristic of albinism and is defined by retention of inner retinal layers (including the GCL and IPL) at the incipient fovea, but this study shows unique features of GCL and IPL topography that have not been previously described. Another study (published during peer review of our study) examined GCL topography in albinism and found a “temporal to central shift” in GCL thickness 40 ; thus, our observations largely agree with that study. We expand on the findings of Brücher et al 40 by also describing the IPL and examining these layers in a larger participant cohort.…”

“…Another study (published during peer review of our study) examined GCL topography in albinism and found a “temporal to central shift” in GCL thickness 40 ; thus, our observations largely agree with that study. We expand on the findings of Brücher et al 40 by also describing the IPL and examining these layers in a larger participant cohort.…”

“…This finding is also corroborated by another group who noted a similar effect in albinism even when averaging together measurements from both eyes. 40 …”

Characterization of Retinal Thickness in Individuals with Albinism: Baseline Data for a Black South African Population

“…The diagnosis of albinism was based on the recommendation by Kruijt et al 1 as individuals with albinism show variability in clinical signs and may not always present with all of the characteristics associated with the disorder. 1 , 2 , 17 Consequently, Kruijt et al 1 recommend that in the absence of any molecular assessment, the diagnosis of albinism can be made using major and minor clinical diagnostic criteria. The major criteria include ocular (iris and fundus) hypopigmentation, foveal hypoplasia and chiasmal misrouting while the minor criteria include nystagmus, skin and hair hypopigmentation, fundus hypopigmentation and foveal hypoplasia.…”

“… 12 , 15 , 16 In albinism, the development and maturation of the visual system and structures therein are altered because of melanin abnormalities. 9 , 15 , 17 Particularly the normal foveal developmental process, which begins early in gestation and continues postnatally, is prematurely arrested in individuals with albinism. 15 , 18 Consequently, foveal hypoplasia, which refers to the fovea being absent or partially developed, is a common clinical characteristic in individuals with albinism.…”