Functional visual loss

Short description: Loss of vision without any organic cause

Functional visual loss

Specialty| Ophthalmology, Optometry, Psychology, Clinical psychology
Symptoms| Loss of vision
Diagnostic method| Eye examination

Functional visual loss (FVL) also known as Functional vision loss or Nonorganic visual loss (NOVL) is a reduction in visual acuity or loss of visual field that has no physiological or organic basis. This disease can come under the spectrum of functional neurological disorder or somatic symptom disorder.

## Contents

* 1 Disease
* 2 Epidemiology
* 3 Impact
* 3.1 Differential diagnosis
* 4 Investigations
* 5 Treatment
* 6 Further reading
* 7 References

## Disease

In ophthalmology, Functional visual loss is the reduction in visual acuity or visual field that has no physiological or organic basis. This disease can come under the spectrum of functional neurological disorder or somatic symptom disorder under the categorization of the Diagnostic and Statistical Manual of Mental Disorders-5. But recent updates in the DSM-5 state that many patients with FVL do not have any identifiable psychological correlates.[1]

## Epidemiology

The prevalence of Functional visual loss neuro-ophthalmology clinics is said to be 5-12%, and general ophthalmology clinics 1-5%.[2][3] It is said that the total prevalence may be much more higher because patients may also consult their general practitioners, internal medicine physicians, psychiatrists or neurologists.[4]

It is more commonly seen in children at the age group 11–20 years and is seen more commonly in females (63%) than males.[3] Children usually complain bilateral blindness.[2]

## Impact

The social impact of functional vision loss is largely economic. Unrecognized functional vision loss leads to fraudulent claims and undeserved benefits to the people. In case of legal blindness; Because of the financial impact and legal benefits including financial aids or reservations, optometrists and ophthalmologists are obligated to be absolutely certain that functional vision loss does not exist.[5]

### Differential diagnosis

Before diagnosing Functional vision loss, the patient should be tested to rule out conditions which cause defective vision or even blindness in one or both eyes with normal anterior segment and a normal fundus. Some major conditions that should be considered include:

* Amblyopia\- Amblyopia is a condition in which the brain fails to fully process input from one eye and over time favors the other eye and the vision in one become reduced.[6]
* Cortical blindness-Cortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the brain's occipital cortex.[7]
* Retrobulbar neuritis- Retrobulbar neuritis cause of visual loss with normal fundus but there will be relative afferent pupillary defect (RAPD) and abnormal visually evoked responses.[8]
* Cone dystrophy\- Cone dystrophy can cause a blurring of vision, color vision defects and photophobia.[9]
* Chiasmal tumors- In chiasmal tumors, in addition to vision loss, sluggish pupillary reactions and characteristic visual field defects may be noted.[8]

## Investigations

Optometrists and ophthalmologists perform a number of tests to determine the cause of a person’s vision loss. The types of tests vary depending on the type of vision loss the patient complains.

## Treatment

Reassurance is the best treatment that can be given for a patient who is diagnosed with functional vision loss.[2] Ask about stress, anxiety, and depression and refer for appropriate psychiatric treatment if needed.[2] It is important to emphasize to the patient that FVL has a good prognosis, thereby increasing the patient's hope and giving the patient a chance for recovery.[4] Cognitive behavioral therapy or pharmaco therapy for psychiatric ailments may be needed sometimes.[1]

## Further reading

* Enzenauer, Robert W. (2014). Functional ophthalmic disorders : ocular malingering and visual hysteria. William R., M.D. Morris, Thomas O'Donnell, Jill Montrey. Cham. ISBN 978-3-319-08750-4. OCLC 896824726. https://www.worldcat.org/oclc/896824726.

## References

1. ↑ 1.0 1.1 Dhanji, Shanil; Lawlor, Mitchell (April 2017). "Functional visual loss" (in en-US). Current Opinion in Neurology 30 (2): 200–205. doi:10.1097/WCO.0000000000000423. ISSN 1350-7540. PMID 28141741. https://journals.lww.com/co-neurology/Abstract/2017/04000/Functional_visual_loss.14.aspx. Retrieved 2023-04-20.
2. ↑ 2.0 2.1 2.2 2.3 "Functional Visual Loss - EyeWiki". https://eyewiki.aao.org/Functional_Visual_Loss.
3. ↑ 3.0 3.1 "Functional Visual Loss". https://webeye.ophth.uiowa.edu/eyeforum/cases/165-functional-visual-loss.htm.
4. ↑ 4.0 4.1 Chen, Celia S.; Lee, Andrew W.; Karagiannis, Arthur; Crompton, John L.; Selva, Dinesh (1 January 2007). "Practical clinical approaches to functional visual loss" (in en). Journal of Clinical Neuroscience 14 (1): 1–7. doi:10.1016/j.jocn.2006.03.002. ISSN 0967-5868. PMID 16730991. https://www.sciencedirect.com/science/article/abs/pii/S0967586806001809. Retrieved 20 April 2023.
5. ↑ Themes, U. F. O. (26 December 2019). "Functional (Nonorganic) Visual Loss". https://entokey.com/functional-nonorganic-visual-loss/.
6. ↑ "Facts About Amblyopia". September 2013. https://nei.nih.gov/health/amblyopia/amblyopia_guide.
7. ↑ "Dictionary of Eye Terminology". http://www.triadpublishing.com/eyedictionary.shtml.
8. ↑ 8.0 8.1 Khurana, A. K. (2019). Comprehensive ophthalmology (Seventh ed.). New Delhi. p. 344. ISBN 9789352706860.
9. ↑ "Cone Dystrophy - Symptoms, Causes, Treatment | NORD". https://rarediseases.org/rare-diseases/cone-dystrophy/.

* v
* t
* e

* Diseases of the human eye (H00–H59
* 360–379)

Adnexa

| Eyelid|

| Inflammation|

* Stye
* Chalazion
* Blepharitis

|

* Entropion
* Ectropion
* Lagophthalmos
* Blepharochalasis
* Ptosis
* Blepharophimosis
* Xanthelasma

Eyelash|

* Trichiasis
* Madarosis

Lacrimal apparatus|

* Dacryoadenitis
* Epiphora
* Dacryocystitis
* Xerophthalmia

Orbit|

* Exophthalmos
* Enophthalmos
* Orbital cellulitis
* Orbital lymphoma
* Periorbital cellulitis

Conjunctiva|

* Conjunctivitis
* allergic
* Pterygium
* Pinguecula
* Subconjunctival hemorrhage

Globe

| Fibrous tunic|

| Sclera|

* Scleritis
* Episcleritis

|

Cornea|

* Keratitis
* herpetic
* acanthamoebic
* fungal
* Corneal ulcer
* Photokeratitis
* Thygeson's superficial punctate keratopathy
* Corneal dystrophy
* Fuchs'
* Meesmann
* Corneal ectasia
* Keratoconus
* Pellucid marginal degeneration
* Keratoglobus
* Terrien's marginal degeneration
* Post-LASIK ectasia
* Keratoconjunctivitis
* sicca
* Corneal neovascularization
* Kayser–Fleischer ring
* Haab's striae
* Arcus senilis
* Band keratopathy

Vascular tunic|

* Iris
* Ciliary body

* Uveitis
* Intermediate uveitis
* Hyphema
* Rubeosis iridis
* Persistent pupillary membrane
* Iridodialysis
* Synechia

|

Choroid|

* Choroideremia
* Choroiditis
* Chorioretinitis

Lens|

* Cataract
* Congenital cataract
* Childhood cataract
* Aphakia
* Ectopia lentis

Retina|

* Retinitis
* Chorioretinitis
* Cytomegalovirus retinitis
* Retinal detachment
* Retinoschisis
* Ocular ischemic syndrome / Central retinal vein occlusion
* Central retinal artery occlusion
* Branch retinal artery occlusion
* Retinopathy
* diabetic
* hypertensive
* Purtscher's
* of prematurity
* Bietti's crystalline dystrophy
* Coats' disease
* Macular degeneration
* Retinitis pigmentosa
* Retinal haemorrhage
* Central serous retinopathy
* Macular edema
* Epiretinal membrane (Macular pucker)
* Vitelliform macular dystrophy
* Leber's congenital amaurosis
* Birdshot chorioretinopathy

Other|

* Glaucoma / Ocular hypertension / Primary juvenile glaucoma
* Floater
* Leber's hereditary optic neuropathy
* Red eye
* Globe rupture
* Keratomycosis
* Phthisis bulbi
* Persistent fetal vasculature / Persistent hyperplastic primary vitreous
* Persistent tunica vasculosa lentis
* Familial exudative vitreoretinopathy

Pathways

| Optic nerve
Optic disc|

* Optic neuritis
* optic papillitis
* Papilledema
* Foster Kennedy syndrome
* Optic atrophy
* Optic disc drusen

Optic neuropathy|

* Ischemic
* anterior (AION)
* posterior (PION)
* Kjer's
* Leber's hereditary
* Toxic and nutritional

Strabismus
Extraocular muscles
Binocular vision
Accommodation|

| Paralytic strabismus|

* Ophthalmoparesis
* Chronic progressive external ophthalmoplegia
* Kearns–Sayre syndrome

palsies|

* Oculomotor (III)
* Fourth-nerve (IV)
* Sixth-nerve (VI)

Other strabismus|

* Esotropia / Exotropia
* Hypertropia
* Heterophoria
* Esophoria
* Exophoria
* Cyclotropia
* Brown's syndrome
* Duane syndrome

Other binocular|

* Conjugate gaze palsy
* Convergence insufficiency
* Internuclear ophthalmoplegia
* One and a half syndrome

Refraction|

* Refractive error
* Hyperopia
* Myopia
* Astigmatism
* Anisometropia / Aniseikonia
* Presbyopia

Vision disorders
Blindness|

* Amblyopia
* Leber's congenital amaurosis
* Diplopia
* Scotoma
* Color blindness
* Achromatopsia
* Dichromacy
* Monochromacy
* Nyctalopia
* Oguchi disease
* Blindness / Vision loss / Visual impairment

Anopsia|

* Hemianopsia
* binasal
* bitemporal
* homonymous
* Quadrantanopia

subjective|

* Asthenopia
* Hemeralopia
* Photophobia
* Scintillating scotoma

Pupil|

* Anisocoria
* Argyll Robertson pupil
* Marcus Gunn pupil
* Adie syndrome
* Miosis
* Mydriasis
* Cycloplegia
* Parinaud's syndrome

Other|

* Nystagmus
* Childhood blindness

Infections

* Trachoma
* Onchocerciasis

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