Abstract
Introduction
Oligocone trichromacy (OT) is an uncommon cone dysfunction disorder, the mechanism of which remains poorly understood. OT has been thought to be non-progressive, but its long-term visual outcome has been seldom reported in the literature. Our aim was to present two OT patients followed at our institution over 18 years.
Materials and methods
Complete ocular examination, color vision, visual fields, and full-field electroretinography (ERG) were performed at initial presentation and follow-up. Spectral-domain optical coherence tomography (OCT) was performed during follow-up when available at our institution.
Results
Initial ocular examination showed satisfactory visual acuities with normal fundus examination and near-to-normal color vision. However, computerized perimetry demonstrated a ring-shaped scotoma around fixation, and ERG showed a profound cone dysfunction. The discrepancy between preserved color vision and profound cone dysfunction leads to the diagnosis of OT. Subsequent follow-ups over 18 years showed subtle degradation of visual acuities along with progression of the myopia in both patients and slight worsening of color vision in one patient. Initial OCT revealed a focal interruption of the ellipsoid line along with decreased thickness of the perifoveal macula. Subsequent OCT imaging performed 2 years later did not show any macular changes.
Conclusion
Although OT is known to be a non-progressive cone dysfunction, our results suggest that subtle degradation of the visual function might happen over time.
References
Van Lith GHM (1973) General cone dysfunction without achromatopsia. In: Pearlman JT (eds.) 10th ISCERG Symposium. Doc Ophthalmol Proc Ser, vol 2, pp 175–180
Marmor MF, Zrenner E (1995) Standard for clinical electroretinography (1994 update). Doc Ophthalmol 89:199–210
Marmor MF, Fulton AB, Holder GE, Miyake Y, Brigell M, Bach M (2009) International society for clinical electrophysiology of vision. ISCEV standard for full-field clinical electroretinography (2008 update). Doc Ophthalmol 118(1):69–77
Kinnear PR, Sahraie A (2002) New Farnsworth-Munsell 100 hue test norms of normal observers for each year of age 5–22 and for decades 30–70. Br J Ophthalmol 86:1408–1411
Andersen MKG et al (2010) Oligocone trichromacy: clinical and molecular genetic investigations. Invest Ophthalmol Vis Sci 51(1):89–95
Thomas MG, Kumar A, Kohl S, Proudlock FA, Gottlob I (2011) High-resolution in vivo imaging in achromatopsia. Ophthalmology 118:882–887
Michaelides M et al (2004) The cone disfunctions syndromes. Br J Ophthalmol 88:291–297
Michaelides M, Holder GE et al (2004) Oligocone trichromacy: a rare and unusual cone dysfunction syndrome. Br J Ophthalmol 88:497–500
Robson JG, Saszik S, Ahmed J, Frishman LJ (2003) Rod and cone contributions to the a-wave of the electroretinogram of macaque. J Physiol 547:509–530
Michaelides M, Holder GE, Moore AT (2013) Inherited retinal disorders. In: Hoyt CS, Taylor D (eds) Pediatric ophthalmology and strabismus, 4th edn. Elsevier Saunders, pp 449–473
Hartong DT, Pott JWR, Kooijman AC (2007) Six patients with bradyopsia (slow vision). Ophthalmology 114(12):2323–2332
Michaelides M, Li Z, Rana NA, Richardson EC, Hykin PG, Moore AT, Holder GE, Webster AR (2010) RGS9- and R9AP-associated retinopathy. Ophthalmology 117(1):120–127
Chehg JYC, Luu CD, Yong VHK et al (2007) Bradyopsia in asian man. Arch Ophthalmol 125(8):1138–1140
Vincent A, Robson AG, Holder GE (2013) Pathognomonic (diagnostic) ERG: a review and update. Retina 33(1):5–12
Michaelides M, Li Z, Rana NA et al (2010) Novel mutations and electrophysiologic findings in RGS9- and R9AP-associated retinal dysfunction (Bradyopsia). Ophthalmology 117:120–127
Nishiguchi K, Sandberg M, Kooijman A et al (2004) Defects in RGS9 or its anchor protein R9AP in patients with slow photoreceptor deactivation. Nature 427:75–78
Michaelides M et al (2011) Integrity of the cone photoreceptor mosaic in oligocone trichromacy. Invest Ophthalmol Vis Sci 52(7):4757–4763
Audo I, Holder GE et al (2014) Inherited stationary disorders of the retina. In: Puech B, De Laey JJ, Holder GE (eds) Inherited chorioretinal dystrophies. Springer, Berlin, pp 77–98
Acknowledgments
We are grateful to Mr. Philippe Debruyne, Engineer in Exploration of Visual Function and Neuro-Ophthalmology Department, who kindly helped us for the illustration, and to Dr Samuel Bidot and Laura McMaster (Rothschild’s Foundation, Paris, France) for their English revisions.
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Smirnov, V., Drumare, I., Bouacha, I. et al. Long-term follow-up of two patients with oligocone trichromacy. Doc Ophthalmol 131, 149–158 (2015). https://doi.org/10.1007/s10633-015-9508-8
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DOI: https://doi.org/10.1007/s10633-015-9508-8