Night Blindness – Retinitis Pigmentosa
Inherited retinal disease · Tunnel vision · Prof. Dr. Fırat Helvacıoğlu, FEBOS-CR · Veni Vidi Eye Clinic, Caddebostan – Kadıköy, Istanbul
Retinitis pigmentosa is an inherited disease in which the light-sensitive cells of the retina are lost over the years. The first symptom is night blindness; side vision then narrows and tunnel vision develops. Although treatment for the disease itself is limited, associated macular oedema and cataract can be treated, and gene therapy is an option for patients with an eligible genetic diagnosis.
How does a person with retinitis pigmentosa see?
The disease progresses from the periphery towards the centre: first vision in the dark, then side vision declines and “tunnel vision” develops. Also, use the slider to change the stage and switch on the night view.
Because central vision can be preserved for many years, patients can read but may bump into things when walking and struggle with stairs and dark environments. Illustrative simulation © Prof. Dr. Fırat Helvacıoğlu
What is retinitis pigmentosa (night blindness)?
Retinitis pigmentosa is a group of inherited diseases in which the light-sensitive cells of the retina (first rods, then cones) are lost over the years. The first symptom is usually difficulty seeing in the dark and in dim light (night blindness), followed by narrowing of side vision; as the disease progresses, “tunnel vision” develops. Central vision is often preserved for many years.
It affects about one in 4,000 people worldwide. Many genes associated with the disease have been identified to date; inheritance may be autosomal dominant, autosomal recessive or X-linked. Moreover, consanguineous marriage increases the frequency of recessive forms.
Retinitis pigmentosa: what happens in the fundus?
Shows the typical fundus findings of the disease step by step.
- Healthy retinaNormally, rod cells are concentrated in the periphery of the retina, and cone cells in the centre.
- Rod cell lossThe disease starts in the periphery: first night vision, then side vision declines.
- Bone-spicule pigmentationBone-spicule pigment deposits in the periphery, attenuated vessels and a pale optic disc are seen.
- Macular oedema (treatable)In some patients, fluid accumulates at the centre (cystoid macular oedema), but it can be treated with drops or medication.
Symptoms
- Difficulty seeing in the dark, in the evening and in dim environments
- Narrowing of side vision; bumping into door frames and people
- Difficulty adapting from light to dark; discomfort from glare
- Reduced colour and central vision in the advanced stage
Diagnosis and genetic evaluation
First, bone-spicule pigment deposits in the peripheral fundus, attenuated vessels and a pale optic disc are typical. Furthermore, the diagnosis is supported by visual field testing, OCT, fundus autofluorescence and electroretinography (ERG), which measures the electrical response of the retina. Finally, genetic testing identifies the causative gene, helping both with family planning and with assessing eligibility for gene therapy or clinical trials.
Treatable conditions and current approaches
- Cystoid macular oedema: A significant proportion of patients develop fluid at the centre of the retina. Carbonic anhydrase inhibitor drops or tablets are the first-line treatment; intravitreal steroids are used if needed. In addition, these treatments can reduce macular thickness.
- Cataract: Posterior subcapsular cataract is common at an early age in retinitis pigmentosa; well-timed cataract surgery can markedly improve vision.
- Gene therapy: For disease caused by biallelic mutations in the RPE65 gene, a gene therapy called voretigene neparvovec has been approved; in the phase 3 trial, 65% of treated patients successfully completed a mobility course at the lowest light level. However, this treatment is suitable only for patients with a specific genetic diagnosis.
- Vitamin supplements: Evidence that vitamin A and fish oil slow disease progression is weak (Cochrane); however, high-dose vitamin A should only be considered under medical supervision.
- Low vision rehabilitation and protection: Glasses with UV and blue-light filters, appropriate lighting, magnifiers and orientation training make daily life easier.
Frequently asked questions
The course of the disease varies from person to person and by genetic type. However, many patients retain central vision for many years; some may develop severe vision loss later in life.
It depends on the pattern of inheritance. In addition, genetic testing and genetic counselling help determine the likelihood of transmission to children.
No. Vitamin A deficiency, high myopia, cataract and certain medications can also impair night vision. For this reason, the differential diagnosis is made with an eye examination and tests.
No. The approved gene therapy is only for patients with biallelic mutations in the RPE65 gene. However, clinical trials are ongoing for other genes.
Once the visual field narrows, driving may not be safe; fitness to drive is assessed with visual field testing.
References
- Hartong DT et al. Retinitis pigmentosa. Lancet. 2006;368(9549):1795–1809. doi:10.1016/S0140-6736(06)69740-7
- Schwartz SG et al. Vitamin A and fish oils for preventing the progression of retinitis pigmentosa. Cochrane Database Syst Rev. 2020;6(6):CD008428. doi:10.1002/14651858.CD008428.pub3
- Russell S et al. Efficacy and safety of voretigene neparvovec (AAV2-hRPE65v2) in patients with RPE65-mediated inherited retinal dystrophy: a randomised, controlled, open-label, phase 3 trial. Lancet. 2017;390(10097):849–860. doi:10.1016/S0140-6736(17)31868-8
- Chen C et al. Management of cystoid macular edema in retinitis pigmentosa: a systematic review and meta-analysis. Front Med (Lausanne). 2022;9:895208. doi:10.3389/fmed.2022.895208
This page is intended for patient information and does not replace an examination or medical assessment. The treatment that is right for you is determined after an eye examination and measurements.
Retinal and visual field assessment
Prof. Dr. Fırat Helvacıoğlu · Veni Vidi Eye Clinic, Bağdat Caddesi No: 257, Caddebostan – Kadıköy, Istanbul, Türkiye
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