Residual Foveal Cone Structure in CNGB3-Associated Achromatopsia

Christopher S Langlo, Emily J Patterson, Brian P Higgins, Phyllis Summerfelt, Moataz M Razeen, Laura R Erker, Maria Parker, Frederick T Collison, Gerald A Fishman, Christine N Kay, Jing Zhang, Richard G Weleber, Paul Yang, David J Wilson, Mark E Pennesi, Byron L Lam, John Chiang, Jeffrey D Chulay, Alfredo Dubra, William W Hauswirth, Joseph Carroll, ACHM-001 Study Group, Christopher S Langlo, Emily J Patterson, Brian P Higgins, Phyllis Summerfelt, Moataz M Razeen, Laura R Erker, Maria Parker, Frederick T Collison, Gerald A Fishman, Christine N Kay, Jing Zhang, Richard G Weleber, Paul Yang, David J Wilson, Mark E Pennesi, Byron L Lam, John Chiang, Jeffrey D Chulay, Alfredo Dubra, William W Hauswirth, Joseph Carroll, ACHM-001 Study Group

Abstract

Purpose: Congenital achromatopsia (ACHM) is an autosomal recessive disorder in which cone function is absent or severely reduced. Gene therapy in animal models of ACHM have shown restoration of cone function, though translation of these results to humans relies, in part, on the presence of viable cone photoreceptors at the time of treatment. Here, we characterized residual cone structure in subjects with CNGB3-associated ACHM.

Methods: High-resolution imaging (optical coherence tomography [OCT] and adaptive optics scanning light ophthalmoscopy [AOSLO]) was performed in 51 subjects with CNGB3-associated ACHM. Peak cone density and inter-cone spacing at the fovea was measured using split-detection AOSLO. Foveal outer nuclear layer thickness was measured in OCT images, and the integrity of the photoreceptor layer was assessed using a previously published OCT grading scheme.

Results: Analyzable images of the foveal cones were obtained in 26 of 51 subjects, with nystagmus representing the major obstacle to obtaining high-quality images. Peak foveal cone density ranged from 7,273 to 53,554 cones/mm2, significantly lower than normal (range, 84,733-234,391 cones/mm2), with the remnant cones being either contiguously or sparsely arranged. Peak cone density was correlated with OCT integrity grade; however, there was overlap of the density ranges between OCT grades.

Conclusions: The degree of residual foveal cone structure varies greatly among subjects with CNGB3-associated ACHM. Such measurements may be useful in estimating the therapeutic potential of a given retina, providing affected individuals and physicians with valuable information to more accurately assess the risk-benefit ratio as they consider enrolling in experimental gene therapy trials. (www.clinicaltrials.gov, NCT01846052.).

Figures

Figure 1
Figure 1
Examples of the grades used for OCT phenotyping. The scheme used here is based on that of Sundaram et al., who based their grading on the appearance of the EZ band (also, IS/OS junction). Grade I corresponds to a continuous band, Grade II corresponds to a disrupted band, Grade III corresponds to an absence or collapse of the band, and Grade IV corresponds to the presence of a hyporeflective zone (HRZ). Subjects with outer retinal atrophy were labeled as Grade V. These OCTs are displayed a logarithmically transformed intensity scale. The distribution of grades present in our subjects is given in the Table. Scale bar: 250 μm.
Figure 2
Figure 2
Longitudinal reflectivity profiles from log transformed OCT images of retinas without (A) and with (B) foveal hypoplasia. In both cases, the longitudinal reflectivity profile was averaged over a 5-pixel wide region positioned at the center of the foveal depression. (A) In a subject with normal foveal excavation, the ONL is bounded by hyperreflective peaks corresponding to the ILM and the ELM. (B) In this subject with foveal hypoplasia, the ONL is bounded by hyperreflective peaks corresponding to the OPL and the ELM. For all subjects, the distance between the ELM and the OPL was taken as the foveal ONL thickness., Of our 52 subjects, 37 (71%) had some degree of foveal hypoplasia.
Figure 3
Figure 3
Variability in the foveal cone mosaic in patients with ACHM. (Top) Foveal montages obtained using split-detector AOSLO for two subjects with sparse foveal mosaics—PCI-008 with a peak density of 7,273 cones/mm2 and PCI-007 with 12,231 cones/mm2. (Bottom) Foveal montages for two subjects with relatively contiguous mosaics—PCI-009 with a peak density of 19,835 cones/mm2 and PCI-021 with 44,959 cones/mm2. Scale bar: 50 μm.
Figure 4
Figure 4
Variability in inter-cell distance (ICD). Measurements of ICD from all subjects were made and the CV was calculated for each subject. Shown is a histogram of the distribution of the CV for all ACHM subjects with quantified foveal cone populations. The vertical solid line denotes the mean and dashed lines the range of the normal CV from measurements made on the foveal cone populations of six nondiseased retinas.
Figure 5
Figure 5
Comparison of cone structure determined by OCT and AOLSO. Comparing OCT grade versus peak cone density (A) shows a significant difference among grades I, II, and IV (P = 0.0003), though there remains significant overlap in the ranges of these grades. Comparing ONL thickness to OCT Grade (B) revealed a relationship between these measurements (P = 0.0176). Shaded regions represent the first through third quartile, the horizontal line the median, the extending lines represent the maximum and minimum, the diamond the mean, and circles signify outliers.
Figure 6
Figure 6
Cone structure measurements compared with age. In (A) OCT grade was found to have an age relationship (P = 0.0099), with more severe OCT grades being found in older individuals on average. Shaded regions represent the first through third quartile, the horizontal line the median, the extending lines represent the maximum and minimum, the diamond the mean, and circles signify outliers. In contrast, neither ONL thickness (B) nor peak cone density (C) showed an age relationship. Symbols in (B) and (C) represent the OCT grade: filled circles, grade I; crosses, grade II; squares, grade III; triangles, grade IV.

References

    1. Michaelides M,, Hunt DM,, Moore AT. The cone dysfunction syndromes. Br J Ophthalmol. 2004; 88: 291–297.
    1. Sharpe LT,, Stockman A,, Jägle H,, Nathans J. Opsin genes, cone photopigments, color vision, and color blindness. : Gegenfurtner KR,, Sharpe LT, Color Vision: From Genes to Perception. New York, NY: Cambridge University Press; 1999: 3–52.
    1. Zobor D,, Zobor G,, Kohl S. Achromatopsia: on the doorstep of a possible therapy. Ophthalmic Res. 2015; 54: 103–108.
    1. Thiadens AA,, Somervuo V,, van den Born LI,, et al. Progressive loss of cones in achromatopsia: an imaging study using spectral-domain optical coherence tomography. Invest Ophthalmol Vis Sci. 2010; 51: 5952–5957.
    1. Thomas MG,, McLean RJ,, Kohl S,, Sheth V,, Gottlob I. Early signs of longitudinal progressive cone photoreceptor degeneration in achromatopsia. Br J Ophthalmol. 2012; 96: 1232–1236.
    1. Kohl S,, Marx T,, Giddings I,, et al. Total colour blindness is caused by mutations in the gene encoding the alpha-subunit of the cone photoreceptor cGMP-gated cation channel. Nat Genet. 1998; 19: 257–259.
    1. Kohl S,, Baumann B,, Rosenberg T,, et al. Mutations in the cone photoreceptor G-protein α-subunit gene GNAT2 in patients with achromatopsia. Am J Hum Genet. 2002; 71: 422–425.
    1. Kohl S,, Varsanyi B,, Antunes GA,, et al. CNGB3 mutations account for 50% of all cases with autosomal recessive achromatopsia. Eur J Hum Genet. 2005; 13: 302–308.
    1. Thiadens AA,, Slingerland NW,, Roosing S,, et al. Genetic etiology and clinical consequences of complete and incomplete achromatopsia. Ophthalmology. 2009; 116: 1984–1989.
    1. Carvalho LS,, Xu J,, Pearson R,, et al. Long-term and age-dependent restoration of visual function in a mouse model of CNGB3-associated achromatopsia following gene therapy. Hum Mol Genet. 2011; 20: 3161–3175.
    1. Komáromy A,, Alexander JJ,, Rowlan JS,, et al. Gene therapy rescues cone function in congenital achromatopsia. Hum Mol Genet. 2010; 19: 2581–2593.
    1. Pang JJ,, Deng WT,, Dai X,, et al. AAV-mediated cone rescue in a naturally occurring mouse model of CNGA3-achromatopsia. PLoS One. 2012; 7: e35250.
    1. Du W,, Tao Y,, Deng W,, et al. Vitreal delivery of AAV vectored Cnga3 restores cone function in CNGA3−/−/Nrl−/− mice, an all-cone model of CNGA3 achromatopsia. Hum Mol Genet. 2015; 24: 3699–3707.
    1. Ezra-Elia R,, Banin E,, Honig H,, et al. Flicker cone function in normal and day blind sheep: a large animal model for human achromatopsia caused by CNGA3 mutation. Doc Ophthalmol. 2014; 129: 141–150.
    1. Banin E,, Gootwine E,, Obolensky A,, et al. Gene augmentation therapy restores retinal function and visual behavior in a sheep model of CNGA3 achromatopsia. Mol Ther. 2015; 23: 1423–1433.
    1. Zelinger L,, Cideciyan AV,, Kohl S,, et al. Genetics and disease expression in the CNGA3 form of achromatopsia: steps on the path to gene therapy. Ophthalmology. 2015; 122: 997–1007.
    1. Jacobson SG,, Aleman TS,, Cideciyan AV,, et al. Identifying photoreceptors in blind eyes caused by RPE65 mutations: prerequisite for human gene therapy success. Proc Natl Acad Sci U S A. 2005; 102: 6177–6182.
    1. Spaide RF,, Curcio CA. Anatomical correlates to the bands seen in the outer retina by optical coherence tomography: literature review and model. Retina. 2011; 31: 1609–1619.
    1. Jonnal RS,, Kocaoglu OP,, Zawadzki RJ,, Lee SH,, Werner JS,, Miller DT. The cellular origins of the outer retinal bands in optical coherence tomography images. Invest Ophthalmol Vis Sci. 2014; 55: 7904–7918.
    1. Carroll J,, Choi SS,, Williams DR. In vivo imaging of the photoreceptor mosaic of a rod monochromat. Vision Res. 2008; 48: 2564–2568.
    1. Merino D,, Duncan JL,, Tiruveedhula P,, Roorda A. Observation of cone and rod photoreceptors in normal subjects and patients using a new generation adaptive optics scanning laser ophthalmoscope. Biomed Opt Express. 2011; 2: 2189–2201.
    1. Hood DC,, Zhang X,, Ramachandran R,, et al. The inner segment/outer segment border seen on optical coherence tomography is less intense in patients with diminished cone function. Invest Ophthalmol Vis Sci. 2011; 52: 9703–9709.
    1. Genead MA,, Fishman GA,, Rha J,, et al. Photoreceptor structure and function in patients with congenital achromatopsia. Invest Ophthalmol Vis Sci. 2011; 52: 7298–7308.
    1. Aboshiha J,, Dubis AM,, Cowing J,, et al. A prospective longitudinal study of retinal structure and function in achromatopsia. Invest Ophthalmol Vis Sci. 2014; 55: 5733–5743.
    1. Dubis AM,, Cooper RF,, Aboshiha J,, et al. Genotype-dependent variability in residual cone structure in achromatopsia: towards developing metrics for assessing cone health. Invest Ophthalmol Vis Sci. 2014; 55: 7303–7311.
    1. Sundaram V,, Wilde C,, Aboshiha J,, et al. Retinal structure and function in achromatopsia: implications for gene therapy. Ophthalmology. 2014; 121: 234–245.
    1. Roorda A,, Romero-Borja F,, Donnelly WJ,, III,, Queener H,, Hebert T,, Campbell M. Adaptive optics scanning laser ophthalmoscopy. Opt Express. 2002; 10: 405–412.
    1. Dubra A,, Sulai Y,, Norris JL,, et al. Noninvasive imaging of the human rod photoreceptor mosaic using a confocal adaptive optics scanning ophthalmoscope. Biomed Opt Express. 2011; 2: 1864–1876.
    1. Rossi EA,, Chung M,, Dubra A,, Hunter JJ,, Merigan WH,, Williams DR. Imaging retinal mosaics in the living eye. Eye. 2011; 25: 301–308.
    1. Scoles D,, Sulai YN,, Langlo CS,, et al. In vivo imaging of human cone photoreceptor inner segments. Invest Ophthalmol Vis Sci. 2014; 55: 4244–4251.
    1. Horton JC,, Parker AB,, Botelho JV,, Duncan JL. Spontaneous regeneration of human photoreceptor outer segments. Sci Rep. 2015; 5: 12364.
    1. Sun LW,, Johnson RD,, Langlo CS,, et al. Assessing photoreceptor structure in retinitis pigmentosa and Usher syndrome. Invest Ophthalmol Vis Sci. 2016; 57: 2428–2442.
    1. Scoles D,, Flatter JA,, Cooper RF,, et al. Assessing photoreceptor structure associated with ellipsoid zone disruptions visualized with optical coherence tomography. Retina. 2016; 36: 91–103.
    1. Tanna H,, Dubis AM,, Ayub N,, et al. Retinal imaging using commercial broadband optical coherence tomography. Br J Ophthalmol. 2010; 94: 372–376.
    1. Schneider CA,, Rasband WS,, Eliceiri KW. NIH, Image to ImageJ: 25 years of image analysis. Nat Methods. 2012; 9: 671–675.
    1. Staurenghi G,, Sadda S,, Chakravarthy U,, Spaide RF, International Nomenclature for Optical Coherence Tomography (IN•OCT) Panel. Proposed lexicon for anatomic landmarks in normal posterior segment spectral-domain optical coherence tomography: The IN•OCT consensus. Ophthalmology. 2014; 121: 1572–1578.
    1. Thomas MG,, Kumar A,, Mohammad S,, et al. Structural grading of foveal hypoplasia using spectral-domain optical coherence tomography a predictor of visual acuity? Ophthalmology. 2011; 118: 1653–1660.
    1. Thomas MG,, Kumar A,, Kohl S,, Proudlock FA,, Gottlob I. High-resolution in vivo imaging in achromatopsia. Ophthalmology. 2011; 118: 882–887.
    1. Hammer DX,, Iftimia NV,, Ferguson RD,, et al. Foveal fine structure in retinopathy of prematurity: an adaptive optics Fourier domain optical coherence tomography study. Invest Ophthalmol Vis Sci. 2008; 49: 2061–2070.
    1. Curcio CA,, Messinger JD,, Sloan KR,, Mitra A,, McGwin G,, Spaide RF. Human chorioretinal layer thicknesses measured in macula-wide high-resolution histologic sections. Invest Ophthalmol Vis Sci. 2011; 52: 3943–3954.
    1. Dubis AM,, Costakos DM,, Subramaniam CD,, et al. Evaluation of normal human foveal development using optical coherence tomography and histologic examination. Arch Ophthalmol. 2012; 130: 1291–1300.
    1. Dubra A,, Sulai Y. Reflective afocal broadband adaptive optics scanning ophthalmoscope. Biomed Opt Express. 2011; 2: 1757–1768.
    1. Dubra A,, Harvey Z. Registration of 2D images from fast scanning ophthalmic instruments. : Fischer B,, Dawant B,, Lorenz C, Biomed Image Registration. Berlin, Germany: Springer-Verlag; 2010; 60–71.
    1. Carroll J,, Dubra A,, Gardner JC,, et al. The effect of cone opsin mutations on retinal structure and the integrity of the photoreceptor mosaic. Invest Ophthalmol Vis Sci. 2012; 53: 8006–8015.
    1. Wilk MA,, McAllister JT,, Cooper RF,, et al. Relationship between foveal cone specialization and pit morphology in albinism. Invest Ophthalmol Vis Sci. 2014; 55: 4186–4198.
    1. Zhang T,, Godara P,, Blancob ER,, et al. Variability in human cone topography assessed by adaptive optics scanning laser ophthalmoscopy. Am J Ophthalmol. 2015; 160: 290–300.
    1. Lujan BJ,, Roorda A,, Knighton RW,, Carroll J. Revealing Henle's fiber layer using spectral domain optical coherence tomography. Invest Ophthalmol Vis Sci. 2011; 52: 1486–1492.
    1. Lujan BJ,, Roorda A,, Croskrey JA,, et al. Directional optical coherence tomography provides accurate outer nuclear layer and Henle fiber layer measurements. Retina. 2015; 35: 1511–1520.
    1. Falls HF,, Wolter JR,, Alpern M. Typical total monochromacy. A histological and psychophysical study. Arch Ophthalmol. 1965; 74: 610–616.
    1. Harrison R,, Hoefnagel D,, Hayward JN. Congenital total color blindness: a clincopathological report. Arch Ophthalmol. 1960; 64: 685–692.
    1. Carroll J,, Baraas RC,, Wagner-Schuman M,, et al. Cone photoreceptor mosaic disruption associated with Cys203Arg mutation in the M-cone opsin. Proc Natl Acad Sci U S A. 2009; 106: 20948–20953.
    1. Carroll J,, Neitz M,, Hofer H,, Neitz J,, Williams DR. Functional photoreceptor loss revealed with adaptive optics: an alternate cause of color blindness. Proc Natl Acad Sci U S A. 2004; 101: 8461–8466.
    1. Cideciyan AV,, Hufnagel RB,, Carroll J,, et al. Human cone visual pigment deletions spare sufficient photoreceptors to warrant gene therapy. Hum Gene Ther. 2013; 24: 993–1006.
    1. Nishiguchi KM,, Sandberg MA,, Gorji N,, Berson EL,, Dryja TP. Cone cGMP-gated channel mutations and clinical findings in patients with achromatopsia, macular degeneration, and other hereditary cone diseases. Hum Mutat. 2005; 25: 248–258.
    1. Khan NW,, Wissinger B,, Kohl S,, Sieving P. CNGB3 achromatopsia with progressive loss of residual cone function and impaired rod-mediated function. Invest Ophthalmol Vis Sci. 2007; 48: 3864–3871.
    1. Baseler HA,, Brewer AA,, Sharpe LT,, Morland AB,, Jägle H,, Wandell BA. Reorganization of human cortical maps caused by inherited photoreceptor abnormalities. Nat Neurosci. 2002; 5: 364–370.
    1. Song H,, Chui TY,, Zhong Z,, Elsner AE,, Burns SA. Variation of cone photoreceptor packing density with retinal eccentricity and age. Invest Ophthalmol Vis Sci. 2011; 52: 7376–7384.
    1. Chui TY,, Song H,, Clark CA,, Papay JA,, Burns SA,, Elsner AE. Cone photoreceptor packing density and the outer nuclear layer thickness in healthy subjects. Invest Ophthalmol Vis Sci. 2012; 53: 3545–3553.
    1. Stockman A,, Smithson HE,, Michaelides M,, Moore AT,, Webster AR,, Sharpe LT. Residual cone vision without α-transducin. J Vis. 2007; 7 (4): 8.
    1. Langlo C,, Dubis A,, Michaelides M,, Carroll J. Comment on: CNGB3-achromatopsia clinical trial with CNTF: diminished rod pathway responses with no evidence of improvement in cone function. Invest Ophthalmol Vis Sci. 2015; 56: 1505.

Source: PubMed

Sponsor e collaboratori

Condizioni mediche

Interventi farmacologici

3
Sottoscrivi