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Value of autofluorescence imaging in retinitis pigmentosa

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Jenny Giannis
OPSM Elsternwick VIC

Dr Peter Herse
Luxottica Institute of Learning, Sydney NSW

 

Retinitis pigmentosa (RP) is a group of inherited disorders characterised by a progressive peripheral vision loss (tunnel vision) and poor vision in dim light. It can progress to total central vision loss.

Ocular examination includes visual acuity, perimetry, colour vision testing and retinal imaging. Ideally, electroretinogram assessment and dark adaptometry may be performed. Genetic subtyping may be indicated to identify the particular metabolic defect. Optical coherence tomography (OCT) is not required to diagnose RP, though it can be helpful in detecting cystoid macular oedema.

While there is no cure for RP, it is essential to help patients maximise their vision with a careful refraction and low vision assessment.

Medical management of RP may include prescribing fat-soluble vitamins (vitamin A, vitamin E, ascorbic acid), calcium-channel blockers (diltiazem) and carbonic anhydrase inhibitors (acetazolamide). Surgical management may involve cataract extraction. Experimental procedures for the long-term management of RP include transplantation of retinal pigment epithelial tissue, retinal prosthetic devices, for example a bionic eye, and subretinal gene therapy.

 

Fundus autofluorescence

 

Fundus autofluorescence (FAF) is an imaging technique that maps fluorophores of the ocular fundus. The main retinal fluorophore is A2-E found in lipofuscin that accumulates in the RPE during incomplete breakdown of photoreceptor outer segments. FAF imaging is useful in detecting alterations in RPE function in age-related macular degeneration and hereditary retinal disorders such as Stargardt’s disease, vitelliform dystrophy, pattern dystrophy and RP. In RP, parafoveal hyperfluorescence rings may be seen before lesions are visible with ophthalmoscopy (Figures 1-4).

183-OL-Figure -1_F 183-OL-Figure -2_F

Figure 1. Composite image of RE using Optos Daytona

Figure 2. FAF image of RE using Optos Daytona

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Figure 3. Composite image of LE using Optos Daytona

Figure 4. FAF image of LE using Optos Daytona

Case report

 

A 27-year-old Caucasian female presented for an ocular examination. She complained of ‘spots’ in one of her eyes and difficulty seeing at night. Her sister had an ‘undiagnosed’ eye condition. Best corrected visual acuity was RE 6/7.5 LE 6/9.5. Fundus examination showed bone-spicule pigmentation in both eyes (Figures 1 and 3). An updated prescription and daily living skills advice were provided. The patient was referred to ophthalmology for further tests to confirm the diagnosis.

Optos Daytona widefield retinal imaging was performed using standard and autofluorescence modes. FAF clearly indicates macula involvement in this case, which is not easily seen in the standard ocular image. FAF allows for early detection and clear documentation of RPE dysfunction in RP.

Further reading

Fleckenstein M, Schmitz-Valckenberg S, Holz FG. Fundus autofluorescence imaging in clinical use. Review of Ophthalmology 2010

Telander DG. Retinitis pigmentosa.



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