June 2020
Volume 61, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2020
Towards an objective structural grading scheme of foveal hypoplasia in human albinism
Author Affiliations & Notes
  • Erica N. Woertz
    Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Wisconsin, United States
  • Gelique Ayala
    School of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Niamh Wynne
    Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
    Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Taylor M. Dunn
    Department of Clinical and Diagnostic Services, University of Alabama at Birmingham, Birmingham, Alabama, United States
    Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
  • Deborah Costakos
    Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • C. Gail Summers
    Ophthalmology & Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States
  • Sasha Strul
    Ophthalmology & Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States
  • Arlene V Drack
    Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
  • Joseph Carroll
    Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Wisconsin, United States
    Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Footnotes
    Commercial Relationships   Erica Woertz, None; Gelique Ayala, None; Niamh Wynne, None; Taylor Dunn, None; Deborah Costakos, None; C. Summers, None; Sasha Strul, None; Arlene Drack, None; Joseph Carroll, AGTC (F), MeiraGTx (C), MeiraGTx (F), OptoVue (F), Translational Imaging Innovations (I)
  • Footnotes
    Support  NIH Grants T32GM080202, TL1TR001437, R01EY024969, UL1TR001436, P30EY001931; Vision For Tomorrow
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 5261. doi:
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    • Get Citation

      Erica N. Woertz, Gelique Ayala, Niamh Wynne, Taylor M. Dunn, Deborah Costakos, C. Gail Summers, Sasha Strul, Arlene V Drack, Joseph Carroll; Towards an objective structural grading scheme of foveal hypoplasia in human albinism. Invest. Ophthalmol. Vis. Sci. 2020;61(7):5261.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Human albinism is characterized by foveal hypoplasia (FH). FH severity is often subjectively graded using a categorical scale based on the presence/absence of inner retinal layer extrusion, outer segment (OS) elongation, and outer nuclear layer (ONL) thickening. Here we quantify each of these structural features to develop objective criteria for FH grading.

Methods : Genetic testing and optical coherence tomography (OCT) imaging were performed in 67 subjects with albinism (33 M, 34 F, ages 5-69 years). OCT line scans were acquired at the fovea and graded using a previously published FH grading scheme.a The ratio of maximum OS length to parafoveal OS length (OS ratio) was measured using longitudinal reflectivity profiles,b,c and the foveal ganglion cell-inner plexiform layer (GCIPL) thickness was measured. The ratio of foveal:parafoveal ONL thickness (ONL ratio) was also measured in 22 subjects using directional OCT scans.d Receiver operating characteristic (ROC) analysis was used to determine the optimal cutoff value of GCIPL thickness and OS ratio to differentiate between grade 1, 2, and 3-4. FH grade was reassessed objectively using these cutoff values.

Results : Subjects had oculocutaneous albinism type 1 (OCA1, n=25), OCA2 (n=13), OCA4 (n=2), OCA6 (n=1), ocular albinism (n=2), or Hermansky-Pudlak syndrome (n=2). Twenty-two subjects had absent, inconclusive, or pending genetic testing. Based on subjective FH grading, 29 subjects had grade 1, 10 had grade 2, 23 had grade 3, and 5 had grade 4. Foveal GCIPL thickness ranged from 24.95-81.49 µm (mean±SD: 66.74±12.09), OS ratio ranged from 1.13-2.10 (mean±SD: 1.51±0.24), and ONL ratio ranged from 1.08-2.88 (mean±SD: 1.52±0.44). The area under the ROC curve (AUC) for GCIPL thickness was 0.84 (p<0.0001) and the optimal cutoff was 71.95 µm. The ROC AUC for OS ratio was 0.81 (p<0.0001) and the optimal cutoff was 1.435. Using these cutoff values, objective FH grades agreed with subjective grades in 48/67 subjects.

Conclusions : Objective FH grading does not always agree with subjective grading, as quantitative foveal metrics vary widely in albinism and overlap between subjective FH grades. This indicates that the chronological development of foveal anatomical specializations may be more nuanced than the existing categorical grading scheme suggests.

aPMC5648335
bPMC2838989
cPMC5186335
dPMC6219160

This is a 2020 ARVO Annual Meeting abstract.

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