Retinal detachment

Abstract

Around 5% of GP consultations are said to be eye-related, with loss of sight being the most feared long-term health condition. In 2013 there were 4 500 000 GP consultations related to eye health. The RCGP has stated that 50% of sight loss could be avoided through earlier diagnosis and improved eye care. It is essential that retinal detachment is recognised as an ophthalmological emergency and referred for urgent surgical repair to prevent visual loss. This article outlines the causes, presentation and management of retinal detachment, emphasising risk factors and clinical features that facilitate early diagnosis and prompt referral.

What is retinal detachment?

The retina consists of a neurosensory layer and a pigment epithelium layer attached to the choroid (Pokhrel and Loftus, 2007). The potential subretinal space between the two retinal layers is closed in the healthy eye. When the neurosensory retina separates from the underlying retinal pigment epithelium, fluid accumulates within the subretinal space and retinal detachment is said to have occurred (Kang and Luff, 2008). This can be seen in Fig. 1.

Figure 1.

Diagram of the retinal detachment process.

Why does this happen?

Retinal detachments most commonly occur secondary to a retinal tear as illustrated in Fig. 1. The posterior chamber of the eye contains the vitreous gel which firmly adheres to the retina. With age, the vitreous gel loses water content and shrinks. This shrinkage causes the vitreous medium to create traction on the retina and the gel may then detach from the retina. The posterior vitreous detachment occurs over a period of about 6 weeks. During this time, patients can experience the classic symptom of photopsia, due to vitreous fluid traction on the retina. This is described as bright white flashes of light (similar to the appearance of lightning in the sky) in one eye. It is very different from the scintillating kaleidoscopic pattern of coloured lights experienced in both eyes during the visual aura of a migraine.

The vitreous fluid firmly adheres to the retina at the equator and at the optic disc. When the vitreous gel detaches from the optic disc, a Weiss ring may be visible on examination. Patients may be aware of this and describe a new large floater.

A retinal tear occurs in an area where the vitreous gel is firmly adhered to the retina and traction causes a break in the retina rather than the vitreous gel separating from the retina. A retinal tear can occur anywhere within the retina; however, the location of the tear does differ according to frequency seen and patient age. This can be seen in Fig. 2. The aetiology of retinal detachment is either rhegmatogenous or non-rhegmatogenous, and these occur singularly or in combination (Brinton and Wilkinson, 2009).

Figure 2.

Location of retinal tears with age.

Rhegmatogenous detachment

Rhegmatogenous detachment is the most common cause of retinal detachment. It occurs following a break in the retina that allows fluid from the vitreous cavity (often liquified vitreous gel) to pass into the subretinal space, separating the neurosensory layer (Steel, 2014). This is often seen in posterior vitreous detachment (PVD) as this creates a tractional force on the retina and a subsequent retinal tear. If a retinal tear occurs, fluid in the vitreous cavity of the eye can pass into the subretinal space and cause the retina to detach. The rate at which a retinal detachment occurs depends on the position of the tear; superior tears progress more quickly. Detachments start in the peripheral retina and progress to involve the macula.

Rhegmatogenous retinal detachments are broadly classified as ‘macula on’ or ‘macula off’ (Wilkinson and Rice, 1997). If the macula is still attached, ‘macula on’, the visual prognosis following surgery is good. If the retinal detachment has progressed to ‘macula off’, the visual potential of the eye is more likely to be compromised (Williamson et al., 2013). Therefore, it is very important to identify and treat retinal tears before they progress to retinal detachment.

Non-rhegmatogenous detachments: Exudative

Exudative retinal detachments occur when subretinal fluid accumulates in the subretinal space in the absence of retinal breaks or traction. This may occur secondary to neoplasm, vascular lesions and inflammation such as posterior scleritis. This is not associated with vitreous traction and patients do not complain of photopsia. Vitritis in inflammatory processes may cause floaters.

Non-rhegmatogenous detachments: Tractional

The main causes of non-rhegmatogenous tractional retinal detachment are proliferative retinopathies such as diabetic and sickle cell retinopathy and penetrating posterior segment trauma. Pathological vitreoretinal adhesions contract and pull the retinal neurosensory layer away from the pigment epithelium. Photopsia and floaters are usually absent, as this type of detachment is not associated with an acute posterior vitreous detachment.

How often does retinal detachment occur and who is at risk?

Retinal detachments are relatively uncommon, affecting 1:10 000 people per year with a lifetime risk of this occurring by the age of 85 years estimated at 3% (Kang and Luff, 2008). There are specific causes and risk factors for retinal detachment. Awareness of these can increase clinical suspicion of retinal detachment and encourage earlier diagnosis. The risk factors for retinal detachment are listed in Table 1. Box 1 details the symptoms of detachment that should also raise clinical suspicion of retinal detachment.

Table 1.

Risk factors for development of retinal detachment.

Cause/risk factor	Explanation
Ageing	Mostly occurs in people over the age of 60 years
Familial	Tendency for inherited myopia or degenerative retinal lesions
Myopia	Increases the risk of PVD with the peripheral retina thinned and more susceptible to tears (often if more than minus 6.00D)
Previous history	1:8 people with history of retinal detachment in one eye go on to develop the condition in the contralateral eye
Previous cataract surgery	Increases PVD with 1% of people weeks to years following cataract surgery developing retinal detachment
Head/eye trauma	Especially with blunt trauma. May be a delayed presentation → wear eye protection
Systematic disease	• Diabetes mellitus: Proliferative retinopathy • Inflammatory conditions (such as uveitis and scleritis): Exudative retinal detachment • Ocular malignancy: Exudative RD • Congenital eye disease: Glaucoma, cataract or retinopathy of prematurity

Adapted from NICE (2015).

Investigation in primary care

When patients present with visual symptoms, general eye examination is essential and indicated before referral to an ophthalmologist. Visual acuity is especially important, and should be documented before further management. Examination can be documented and summarised as below (National Institue for Health and Clinical Excellence (NICE), 2015; RCGP):

Visual acuity: Assessment of corrected vision for each eye using a Snellen chart

Visual field: Detachment will cause monocular visual field defects

Pupillary reaction: Direct response, consensual response, detachments will cause relative afferent pupillary defect

Fundoscopy: detachment is signalled by loss of red reflex, grey retina and a hole or tear may be seen. Do not be reassured by normal fundoscopy, as small tears can be difficult to observe

When and how to refer?

Patients with suspected retinal detachment need emergency referral to the ophthalmologist, and patients should be seen the same day so that surgical intervention can be planned with the appropriate urgency. It is essential to avoid unnecessary delays in treatment, as early treatment is more likely to preserve vision (Kang and Luff, 2008; Minihan et al., 2001; Sodhi et al., 2008; Williamson et al., 2013).

Prognosis

Without surgical management of patients with retinal detachment, visual loss in the affected eye is almost inevitable (Feltgen and Walter, 2014). Retinal detachment can be classified (Wilkinson and Rice, 1997) as ‘macula on’ (when fovea is attached) or ‘macula off’ (when central retinal detachment has occurred). Patients with ‘macula on’ detachment have a better prognosis with a post-operative visual acuity of 6/12 or better in 90% of successfully repaired detachments. In patients with ‘macula off’ retinal detachment, 50% will achieve a post-operative visual acuity of 6/15, but if the macula has been detached for 1 week, this level of acuity is rarely achieved (Wilkinson and Rice, 1997).

Management

Retinal tears, but no detachment

Two main types of treatment are used to prevent fluid from entering the subretinal space and retinal detachment. These are:

Laser treatment around the tear to cause retinal adherence

Cryoprobe applied to the area of the retina around the tear

Retinal detachment

Patients may be suitable for day-case surgery, but admission for overnight stay post-operatively may be required. The most common primary surgical interventions in the effective management of retinal detachment are scleral buckling, pneumatic retinopexy and vitrectomy (Sharma et al., 2004). The aim of these techniques is to close retinal breaks and relieve vitreoretinal traction. The choice of technique is dependent on various factors, including the size, location and number of retinal breaks. The ability of the patient to maintain posture is also a factor, as tamponade agents require patients to maintain the correct position (Steel, 2014).

Pneumatic retinopexy uses a gas to act as an internal tamponade. Two main types are used: SF6 gas is shorter-acting and lasts 2 to 3 weeks, whereas C3F8 can stay in the eye for 12 weeks (Moorfields, 2018). A diagrammatic representation of pneumatic retinopexy is shown in Fig. 3.

Figure 3.

Pneumatic retinopexy.

Silicon oil is often used in repeat detachments and complex cases. Silicone oil is usually removed from the eye after a few months, but is occasionally left in the eye (Sharma et al., 2004).

Post-operative problems

It is very common to use gas in retinal surgery to provide an internal tamponade on the retina. As the gas bubble begins to disperse, patients will often be aware of a fluid level in the operated eye. They will be able to see above this, but vision may be blurred beneath the fluid level. The gas will disperse until there is a small bubble at the bottom of the patient’s vision and this eventually disappears (Kang and Luff, 2008).

Patients should not fly while the gas is in the eye or be administered nitrous oxide (Moorfields, 2018). Postoperatively, initial discomfort and bruising is to be expected. Patients experience blurred vision that can persist for days to weeks following surgery (Moorfields, 2018). Any pain or deterioration in vision is unusual and requires assessment. Headache and nausea also require clinical review (Kang and Luff, 2008).

Driving implications

The Driver and Vehicle Licensing Agency (DVLA) must be informed of retinal treatment in both eyes. For patients who hold a Group 1 licence, the DVLA must be informed if vision is affected. Patients holding a Group 2 licence must inform the DVLA if retinal treatment has occurred in a single or both eyes (DVLA, 2019; RNIB, 2017). Table 2 provides a summary of DVLA guidance for both Group 1 and Group 2 drivers.

Table 2.

DVLA guidance on vision requirement for fitness to drive.

Group 1 driver	Group 2 driver
Read a registration plate at 20 m	Acuity of at least 6/7.5 in best eye and 6/60 in poorer eye
Acuity of 6/12 with both eyes open	Glasses not exceeding +8D in either lens
At least 120° of vision horizontally	At least 160° of vision horizontally
Central loss of no more than single scattered point or a cluster of up to three adjoining points	No defect allowed within central vision

Adapted from DVLA (2019).

Box 1.

Symptoms that alert to retinal detachment.

• Flashes (photopsia): Brief, recurrent flashes of light, often in temporal peripheral field

• Floaters: Persisting small grey/dark dots forming ‘strands’ or ‘lace’ that moves with visual field

If a patient has new onset floaters or photopsia, they should be referred for a dilated examination by ophthalmology

• Visual field defect: ‘Curtain of darkness’ dark shadow starting in periphery and moving to centre of vision – can take hours to weeks

If the patient describes a grey area in their vision, this may represent a detachment

• Visual acuity reduction: Occurs when macula involved and very high risk for permanent sight loss

It is important to treat a macula or retinal detachment as an emergency to prevent visual loss

Adapted from Hollands et al. (2009) and Kang and Luff (2008).

Continuing patient care

It is important for GPs to be conversant with different sources of help for visually impaired patients. This will allow appropriate signposting and referral. The impact of a condition affecting eyesight is profound. The psychological impact should not be underestimated. If vision is affected, patients may require a variety of aids to enhance existing vision. This includes the use of low vision aids such as magnifiers and a variety of aids to improve lighting (RNIB, 2017).

A Certificate of Vision Impairment can be issued by an ophthalmologist. Social services will then make contact to arrange a needs assessment and provide advice and assistance with financial concessions.

KEY POINTS

Early diagnosis and referral of patients with retinal detachment greatly improves visual prognosis

Early diagnosis and treatment of retinal tears prevents progression to retinal detachment

Early diagnosis in primary care is improved by knowledge of risk factors and familiarity with common symptoms

Refer all patients with a new history of flashers and floaters to ophthalmology for same-day assessment

Examination of patients with visual symptoms should include an assessment of acuity with a Snellen chart reading documented for each eye

Loss of vision or visual impairment has a major impact on patients’ quality of life, usually with major psychosocial implications

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