Superior segmental optic nerve hypoplasia (SSONH), also known as topless disk syndrome or simply topless optic disc, is a congenital condition characterized by a reduced number of regional ganglion cells (RGCs) in the superior optic disc.Shew, W. and Johnson, R.A. (2018), A case of topless disc syndrome (superior segmental optic hypoplasia). Clin Exp Optom, 101: 707-711. https://doi.org/10.1111/cxo.12690
History In 1977, Petersen and Walton reported segmental optic nerve hypoplasia with normal visual acuity and visual field defects in seventeen children born to diabetic mothers. These findings are associated with what is now recognized as SSONH.Petersen RA, Walton DS. Optic Nerve Hypoplasia With Good Visual Acuity and Visual Field Defects: A Study of Children of Diabetic Mothers. Arch Ophthalmol. 1977;95(2):254–258. doi:10.1001/archopht.1977.04450020055011
Risk Factors Risk factors for topless disk syndrome include being born with a low birth weight or short gestation time, being of the female sex, and being born to a diabetic mother.Han SB, Park KH, Kim DM, Kim TW. Prevalence of superior segmental optic nerve hypoplasia in Korea. Jpn J Ophthalmol. 2009;53(3):225-228. doi:10.1007/s10384-009-0663-x Maternal gestational diabetes is considered to be the strongest risk factor for SSONH, as demonstrated by multiple animal studies. Despite this, cases of SSONH without a maternal history of diabetes have been described.Takagi, M., Abe, H., Hatase, T. et al. Superior segmental optic nerve hypoplasia in youth. Jpn J Ophthalmol 52, 468–474 (2008). https://doi.org/10.1007/s10384-008-0588-9
Treatment and Prognosis Since SSONH is a non-progressive disease and has a generally good prognosis, treatment is rarely necessary, and studies that follow patients with SSONH display stationary visual field deficits and optical disc morphology.Hayashi, K., Tomidokoro, A., Aihara, M., Tsuji, H., Shirato, S., & Araie, M. (2008). Long-term follow-up of superior segmental optic hypoplasia. Japanese journal of ophthalmology, 52(5), 412
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