When the retina detaches, the patient may see a dark shadow that progresses in the visual field towards the centre within hours or days.
In many cases, there may be a history of vitreous detachment. Other common risk factors include myopia, cataract surgery and sharp or blunt eye injury.
Especially in young myopic persons, the symptoms may progress slowly within weeks or months, and a small peripheral retinal detachment may be almost asymptomatic.
Central visual acuity remains good until the area responsible for seeing fine detail (macula) is detached.
Emergency referral to a hospital with an ophthalmological unit. Timing of the operationdepends primarily on the risk of macular detachment or the estimated time to its detachment.
Epidemiology
The annual incidence of retinal detachment caused by a retinal hole is approximately 10 per 100 000 population.
The cumulative incidence in the total population is 0.2%, i.e. the lifetime risk is 1:500.
The incidence of retinal detachment is about 8-fold in patients with myopia compared with patients with hyperopia or normal refraction.
Aetiology
Retinal detachment is most commonly caused by a hole in the retina.
A retinal hole is often a tear caused by posterior vitreous detachment Vitreous Detachment.
Vitreous humour leaks through the hole underneath the retina and detaches the retina from the pigmented retinal epithelium.
The peripheral retina may be brittle, especially in persons with myopia, thus predisposing to easier tearing.
Retinal detachment may also be caused by exudation of fluid underneath the retina (e.g. in choroidal melanoma or inflammation) or by traction caused by scar tissue (scar membranes after an open globe injury or in proliferative diabetic retinopathy).
As the retina detaches from the pigmented epithelium, the nourishment of the photoreceptor cells from the choroidal circulation ceases and the cells become atrophied.
Symptoms and clinical findings
The primary symptom of retinal detachment is a dark shadow progressing from the peripheral visual field within hours or days. Other or preceding symptoms may include flashes of light or a shower of black specks.
Flashes of light are associated with retinal tear, as swaying of the torn flap causes a rapid sensation of light resembling bright flashes.
A retinal blood vessel severed by such a tear may bleed into the vitreous chamber, causing a shower of black specks in the visual field.
A dark shadow in the visual field indicates that retinal detachment has already occurred.
In a myopic patient or a patient with diabetes, the detachment may progress without clear symptoms during several months, and the patient may not seek help until an extensive part of the visual field disappears or vision is impaired as the fovea detaches.
The eye remains normal in appearance from the outside.
Visual acuity usually remains good until the detachment reaches the area of the macula, perhaps causing central distortion, and if the fovea detaches, visual acuity decreases drastically. Vision should be examined with the patient wearing his/her own glasses, both eyes separately.
Finger perimetry can be used to detect a visual field defect in the affected eye, located opposite to the detachment. A small detachment only causes a small defect in the visual field, and such detachment may be difficult to discern.
The red reflex may show a swaying greyish shadow (red reflex is totally or partially absent depending on the extent of the detachment).
Ophthalmoscopic examination shows a wavy, greyish retina and tortuous vessels (picture 1).
In association with retinal detachment, flashes of light and a visual field defect occur in one eye.
In visual migraine aura, parts of the visual fields of each eye are disturbed in the same direction, a defect as when watching a low-quality television picture expand and continue for several minutes; the progressive serrated margin of the area may oscillate or scintillate. An aura is transient.
There is no visual field defect associated with vitreous detachment.
Vitreous detachment causes abundant, swaying floaters or specks that the patient can, however, see through. There may also be weak flashes of light in the temporal direction, in particular, in an eye accustomed to darkness Vitreous Detachment.
Treatment
Emergency referral to an ophthalmology unit is required
If there is an opaque shadow or a shower of black specks or if visual acuity is significantly reduced.
The operation should be performed as soon as possible, if the fovea is being or has newly been detached.
Detachment of the macula even for a short time often leaves visual acuity permanently impaired, and the prognosis of final visual acuity gets progressively worse as days go by.
The patient should be advised to avoid intense exertion and unnecessary physical activity. Until surgical treatment, the patient should lie as much as possible on the side of the main detachment (i.e. the side opposite to the experienced visual field defect).
Prevention
If vitreous detachment causes symptoms in the visual field, an ophthalmological examination should be performed within one week, at the latest.
In as many as 8-22% of cases of symptomatic vitreous detachment, a retinal tear can be found.
Tears can be found and restricted with laser before the retina starts to detach.
If the symptoms are severe, the patient should be referred for further examination without delay.
Regular checks by an ophthalmologist are recommended if peripheral retinal changes predisposing to detachment have been observed.
References
Flaxel CJ, Adelman RA, Bailey ST, et al. Posterior Vitreous Detachment, Retinal Breaks, and Lattice Degeneration Preferred Practice Pattern®. Ophthalmology 2020;127(1):P146-P181 [PubMed]