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Inherited retinal dystrophies are a major cause of familial blindness.1
Inherited retinal dystrophies (IRDs) are a diverse group of degenerative eye diseases usually leading to eventual blindness.1
Inherited retinal dystrophies have overlapping signs and symptoms2–4
- Associated with >270 genes.5
The clinical classification of an IRD relies on a variety of features1:
- Primary target cell (cones vs rods);
- Primarily targeted retinal region (macula vs periphery);
- Age of onset and severity of visual impairment;
- Absence/presence of extra-retinal clinical involvement (isolated vs syndromic forms).
IRD phenotypes1,5,6
- Retinitis pigmentosa
- Leber congenital amaurosis
- Congenital stationary night blindness
- Achromatopsia (colour blindness)
- Choroideremia
- Stargardt disease
- Best disease
- Sorsby fundus dystrophy
- Usher syndrome
- Bardet-Biedl syndrome
- The majority of patients (>50%) have vision impairment in early childhood.1,4,7
- Early-onset IRDs can progress quickly, leading to legal blindness in early adulthood.4,7
- IRDs result in progressive loss of rods and/or cones.1
Permit earlier intervention8
Improve accuracy of prognosis, decision-making and management8
Address uncertainty8
IRD patients can exhibit:
Vision impairment:
Loss of visual acuity1,4,7
Young children: <20/200*
Adolescents/adults: 20/200 or worse
Restricted visual fields1,4,7
Patients may report that they have “tunnel vision”.
Parents may report young children bump into things in low light.
Reduced colour vision1,4,7
Night blindness1,4,7
Nyctalopia; common aspect of a rod-cone dystrophy.
Difficulty with dark adaptation1,7,9
Light sensitivity (photophobia)7,9
Fundus abnormalities:
Fundus abnormalities1,4,7†
Pigmentary changes, retinal atrophy, vessel attenuation, optic nerve pallor.
Lack of fundus autofluorescence1,4,7
Electrophysiological:
Reduced/undetectable ERG1,4,9
Physical abnormalities:
Nystagmus1,4,7
Uncontrolled/repetitive eye movements.
Early onset in children (common aspect of a rod-cone dystrophy).
Failure to fix and follow10
In infants.
Other systems/organs:
Some IRDs can be syndromic and may affect other systems/organs.
For example, Usher syndrome also results in hearing loss.5
*Young children can often present with near-normal VA.
†This image was originally published in the Retina Image Bank. David Callan, MD. Retinitis Pigmentosa. Retina Image Bank. 2014;17341. © The American Society of Retina Specialists.
ERG, Electroretinogram; IRD, inherited retinal dystrophy; VA, visual acuity.
References
- Sahel JA Cold Spring Harb Perspect Biol 2015;5.2:a017111.
- Lee K and Garg S Genet Med 2015;17(4):245.
- Khan Z et al. Int J Adv Med 2016;1–8.
- Di Ioro V et al. Genes 2017;8:280–297.
- RetNet. https://sph.uth.edu/retnet/sum-dis.htm (Accessed October 2022).
- Nash BM et al. Transl Pediatr 2015;4(2):139.
- Chung D et al. Am J Ophthalmol 2019;199:58–70.
- American Academy of Ophthalmology®, IRD Clinical Statement. 2016. https://www.aao.org/clinical-statement/recommendations-on-clinica-lasses... (Accessed September 2022).
- Fahim AT et al. 2000. https://www.ncbi.nlm.nih.gov/books/NBK1417/ (Accessed October 2022).
- Cideciyan AV. Prog Retin Eye Res 2010;29(5):398–427.