Eye clinic - Retinal detachment
Ophthalmologist Dr Mark Llewellyn discusses a case of retinal detachment
This 69-year-old man presents to his GP because a few days ago he noticed a slight loss of vision in his left eye, which has become worse overnight.
He says it feels as if a curtain is coming up over his eye. He is worried because he had cataract surgery six weeks ago. There is no pain, diplopia or halos, but he has noticed ‘flashing lights' on the left and some floaters about 10 days ago.
Visual acuity in his right eye is normal, but there is significant impairment in his left – he can count fingers at 1m distance. His fields seem normal. A dilated fundal examination shows an area of subretinal fluid with a ridged pattern in the left eye.
He is referred immediately to the emergency eye clinic and is diagnosed with rhegmatogenous retinal detachment. He is treated surgically. A sclera buckle is used to move the retina back against the choroid. The quick referral and early presentation means he regains good acuity in the eye.
There are three types of retinal detachment:
- rhegmatogenous – caused by vitreous fluid entering a retinal break and separating the retina from the choroid
- exudative or serous detachment – subretinal fluid accumulates without a break, usually because of inflammation or a tumour
- tractional retinal detachment – adhesions between the vitreous gel and the retina cause a mechanical separation without a break.
In this case, rhegmatogenous retinal detachment may have been caused by the cataract surgery, which creates more space in the vitreous chamber and allows the vitreous jelly to shift and tug on the retina.
- Patients often describe a black curtain falling over their vision.
- Visual acuity is usually reduced in the affected eye, but a marked drop suggests the macula has become detached.
- Photopsias arise from the mechanical stimulation of the retina by vitreoretinal traction.
- Severe myopia, aphakia or pseudophakia, intraocular surgery, and conditions like sickle-cell disease or a family history of retinal detachment increase the risk.
- Almost 60% of breaks are seen in the upper temporal quadrant.
- Test visual acuity in both eyes.
- Fundal examination shows an opaque colour over the site of detachment with a corrugated appearance – it moves freely as the eye moves.
- A retinal break in the shape of a horseshoe or flap is often present.
Suspected retinal detachment is an emergency.1
Differential diagnoses include acute retinal necrosis, cytomegalovirus retinitis and senile retinoschisis.
The only treatment is surgery to close all the breaks with minimum associated damage. Up to 95% of patients can have an anatomical success, but visual prognosis depends on whether the macula is still attached. Once the macula is detached the photoreceptors start to degenerate, impairing visual recovery, and less than 50% of patients reach acuity of 6/15 or better.
Dr Mark Llewellyn is a consultant ophthalmologist at the Powys Teaching Health Board in Brecon, Wales
1 Haimann MH, Burton TC and Brown CK. Epidemiology of retinal detachment. Arch Ophthalmol 1982;100:289-92