Please take a history and examine this 40 year old man with visual loss
HISTORY (3 mins)
- Since when
- Sudden/gradual
- Painful or painless
- 1 or both eyes
- Is it getting worse
- Blurring vs distortion vs bits missing (bumping into things) vs double vision
- If bits missing- which bits? Centre or periphery? Top/bottom?
- If blurring- close up/distance
- Any treatments
- Other symptoms (causes of gradual painless visual loss)
- Cataract: glare? Colours dull?
- ARMD: wavy lines?, difficulty reading? Black spot in centre?
- COAG: bumping into things?
- Diabetic retinopathy: Diabetes, glucose control, BP, eye checks
- ON: headache, colour vision, blurred centre
- Drugs: amiodarone, ethambutol, isoniazid, hydroxychoroquine, steroids, sildenafil, tetracyclines
- RP: poor night vision, ask about impaired dark adaptation- do they have difficulty entering movie theatres or problems when going outside into a brightly lit environment. Screen for symptoms of other RP syndromes- hearing, heart problems, balance, kidney, liver problems, sense of smell, fx
- Fx visual problems
- PMH
- Dx including treatments already tried, ask specifically about drugs which can affect vision- are they taking amiodarone, ethambutol, isoniazid, hydroxychoroquine, chloroquine, steroids, sildenafil, tetracyclines
- Sx- do they drive
EXAMINE (3 mins)
- Don’t miss a white stick/Braille!
- VA (use snellen chart) – Reduced VA (normal early on)
- VF- loss of peripheral vision
- Pupils
- Eye movements: if reduced eye movements consider kearns-sayre syndrome
- Fundoscopy: Typically the optic disc is pale and there is bilateral widespread black dots or clumps of dots in a pattern like bone spicules on the retina
- Check for hearing aid and test hearing, don’t miss polydactyly/scar from finger amputation, check for ataxia, peripheral neuropathy, icthyosis, PPM/ICD box.
ICE and EXPLANATION (2 mins)
A suggested explanation is as follows.
“There are many causes of loss of vision but it sounds like you may have the same condition as your brother- an inherited cause of gradual loss of vision called retinitis pigmentosa. The retinal cells at the back of the eye stop working properly. I’m going to refer you to an eye doctor and genetic expert. The eye doctor will probably want to take some photographs of the back of your eye and do some eye tests. Unfortunately there is no cure. Research is ongoing. There is support available from people with the same condition and with equipment such as magnifiers. You need to stop driving until assessed by eye doctor “
VIVA
Retinitis Pigmentosa encompasses a group of inherited disorders of the retina. There is loss of photoreceptors. It causes progressive and severe visual loss. It occurs in 1 in 3000-4000 and presents between 10-30 years old.
Night vision is difficult and there is a gradual reduction in peripheral field of vision and later reduced visual acuity and colour vision. It affects both eyes.
Inheritance can be AD, AR, X-linked, or rarely mitochondrial or digenic.
Syndromic RP:
- Usher’s Syndrome; congenital deafness and RP, balance problems
- Laurence-Moon Syndrome or Bardet-Biedl Syndrome; obese, deaf, hypogonadism, dwarfism, renal failure and hepatic fibrosis, diabetes, low IQ, polydactyly/syndactyly, dilated cardiomyopathy
- Refsum’s disease: ataxia, deaf, RP, Peripheral neuropathy, icthyosis, anosmia, cardiac arrhythmias, short metacarpals and metatarsals
- Kearns-Sayre syndrome; RP, chronic progressive external opthalmoplegia, cardiac conduction defects, ataxia, dysphagia, deafness
- Alstrom’s syndrome: RP, deafness, cardiomyopathy, obesity, diabetes
- Joubert’s syndrome: ataxia, learning difficulties, renal cysts, sleep apnoea, polydactyly
- Senior-Loken Syndrome- RP, kidney disease
- Abetalipoproteinaemia: failure to thrive, poor growth, fat and blood in stool, RP, ataxia
- Alpha-tocopherol transport protein deficiency: RP, ataxia, and vitamin E deficiency.
Investigations:
- Formal assessment of visual acuity
- VF assessment called Goldmann kinetic perimetry test: mid-peripheral VF defects are one of the pathognomonic features of RP
- Colour vision testing
- Retinal photography
- Electroretinogram: abnormal ERGs are an essential feature of RP; decreased amplitude and increased latency
- Genetic testing
- Optical coherence tomography for all patients with worsened central visual acuity
- Audiology, ECG
Differential diagnoses:
Traumatic retinopathy: several months after blunt or penetrating injury to the eye, the retina may assume an appearance similar to that of RP
Pigmentary retinopathies may occur in rubella, syphilis, toxoplasmosis, and herpes virus infection of the retina.
Drugs can cause a pigmentary retinopathy (chloroquine, hydroxychloroquine, and thioridazine).
Vitamin A deficiency presents with night blindness and malnutrition
Autoimmune retinopathy – Symptoms are clinically indistinguishable from RP. On fundoscopic examination there is no pigmentary changes.
Congenital stationary night blindness: relatively normal-appearing fundus
Management of RP
There is no cure
Optimise remaining vision- visual aids such as glasses, magnifiers. Refer to low visual aid clinic.
Provide psychological support and genetic counselling
Inform the DVLA
High doses of vitamin A slow the rate of decline of retinal function. It is unclear if small potential benefits of vitamin A supplementation outweigh the potential risks so it is not routinely recommended
Dietary modification is the definitive therapy for three rare forms of retinitis pigmentosa; Abetalipoproteinaemia (vitamin A+E supplementation), Refsums disease (reduce intake of foods containing phytanic acid), Familial isolated vitamin E deficiency (alpha-tocopherol transport protein deficiency: treatment with vitamin E)
Experimental approaches to treatment for RP, under active investigation, include gene therapy, transplantation of fetal retinal cells or stem cells, and electronic retinal prostheses
Written by Sarah Kennedy
Resources used to make this document include those listed on the webpage and also:
BMJ Best Practice Retinitis pigmentosa
https://patient.info/doctor/Retinitis-Pigmentosa