Abstract
Cataract surgery has become one of the commonest and safest
procedures to be performed in ophthalmology departments across
the UK. Optometrists and other health care professionals have
become increasingly involved in post-operative care and it
is essential that they are able to recognise and to respond
to the rare complications resulting from this surgical procedure.
Corneal oedema, raised intraocular pressure, corneal abrasion,
wound leak, suture complications, iris prolapse, incarcerated
vitreous, severe anterior uveitis and displacement of the
intraocular lens may occur as early complications. Cystoid
macular oedema, endophthalmitis, retinal detachment, posterior
capsule opacification and unsatisfactory refractive error
may arise as later complications. This article reviews the
nature and appearance of each of these complications.
Keywords
Cataract surgery, co-management, complications
Introduction
As we embark upon the 21st century, cataract surgery has
become one of the most frequently performed procedures in
ophthalmology departments across the United Kingdom.1.
Improved surgical techniques have meant that it has also become
one of the safest and most successful of ophthalmic procedures.
However, the number of patients requiring cataract extraction
has often exceeded the surgical capacity, and the dual factors
of an increasing elderly population (10.6% increase in people
aged over 60 from 1999 to 2009)2
and patients presenting for surgery at an earlier stage, mean
that this problem is set to get worse.
In recent years, optometry, both within the Hospital Eye
Service and in primary care, has become more involved in the
co-management of cataract patients, both pre and post-operatively.
This extended role has been actively promoted by the recent
Government initiative ‘Action on Cataracts’, which has sought
to address the problem of long waiting times. Shorter recovery
times and fewer complications mean that optometrists are well
placed to provide the post-operative aftercare for uncomplicated
cases, improving the convenience to the patient and relieving
the burden placed on the ophthalmic outpatient clinic. This
article will briefly discuss the options for managing post-operative
cataract care, and outline the main clinical complications
that may occur.
The patient journey
There has been much debate recently about the ideal patient
journey’, from their awareness of impaired vision to the completed
treatment episode. For day case patients, it is common practice
to undertake a first day post-operative review, a one week
review and a final check, including refraction, at three to
four weeks. However, the best time intervals at which to see
patients post-operatively has not been systematically evaluated.
Some regard the first day post-op review as unnecessary for
uncomplicated cases1,2, provided
that patients have adequate information regarding post-operative
symptoms and easy access to the hospital should they experience
difficulties. In addition, wider implementation of flexible
roles across NHS organisations has meant that much of the
post-operative care of uncomplicated cases is being carried
out by hospital optometrists, primary care optometrists, nurse
practitioners or GPs.2 These
practices are advocated as ‘ideal’ by the ‘Action on Cataracts’
initiative, since they enhance the convenience to patients
and reduce their visits to hospital. However, when a wider
range of staff are involved, it is essential that clinical
protocols are established and adhered to.
The remainder of this article deals with post-operative
cataract complications divided according to whether they primarily
occur within the first 48 hours after surgery or beyond.
Complications within 48 hours of surgery
The National Cataract Survey 1997/8 found that around 23%
of all patients are likely to experience a surgically related
complication within 48 hours of surgery, ranging from minor
to potentially sight-threatening events.3
Corneal oedema
Probably the commonest early complication is corneal oedema,
often accompanied by folds in Decemet’s membrane. The oedema
can vary in severity from mild to severe, with a corresponding
effect on the visual acuity (Figure
1). Prolonged phacoemulsification or trauma to the corneal
endothelium by instruments, lens fragments, forcible flow
of irrigation fluids or IOL insertion may be the cause of
the oedema.4,5
Patients report hazy or misty vision, “like looking through
ground glass”, but generally experience no or only mild discomfort.
They may feel disappointment or concern about their level
of acuity. However, in the majority of cases, even marked
corneal oedema resolves within the first week, and the patient
can be reassured.
The presence of pre-existing corneal abnormalities (e.g.
Fuch’s endothelial dystrophy) may result in oedema which is
severe and persisting4 (Figure
2). Treatment in these cases may include intensified anti-inflammatory
therapy, and it is only in exceptional cases (less than 1%5,6)
that the endothelial decompensation is such that the oedema
does not eventually resolve. Severe cases, however, may require
penetrating keratoplasty. Patients with a preoperative abnormal
endothelial pattern should be warned of this risk prior to
surgery.
Raised intraocular pressure
The intraocular pressure (IOP) can be expected to rise sharply
immediately following cataract surgery. At the first day post-operative
examination, IOP should already be reducing to normal levels,
and any reading under 30 mmHg is acceptable. Viscoelastic
substances retained in the anterior chamber at the time of
surgery or pre-existing glaucoma are common causes of high
IOP. Intervention is required in approximately 8% of patients.1,3
The incidence of troublesome raised IOP post-operatively may
be minimised by a prophylactic course of acetazolamide for
patients with co-existing glaucoma, as these cases have a
greater risk of damage to an already compromised optic nerve
head. Any pre-existing glaucoma therapy should be resumed
as soon as the eye shield is removed.
A suggested regime for the treatment of post-operative raised
IOP is outlined in Table 1. The use of a Patient Group Direction7
within an NHS Trust enables acetazolamide to be administered
or supplied by named professional staff other than medics,
where the post-operative care has been delegated to them.
However, where the IOP does not respond to acetazolamide,
the surgeon may perform paracentesis, a technique by which
a small amount of aqueous humour is released through the cornea
by a needle.
|
IOP
|
Treatment
|
Follow-up
|
| < 30 mmHg |
none |
See in 1 week |
| 30 - 35 mmHg |
PoM acetazolamide 500mg stat |
See in 1 week |
| >35mmHg |
PoM acetazolamide
500mg stat plus
PoM acetazolamide
250mg qds for 48 hours |
Recheck IOP 1 hour after the stat
dose:
IOP reducing? Yes - see in 1 week
No - refer to surgeon for paracentesis |
| Table 1. Suggested regime
for the treatment of raised IOP at day one post-operatively |
|
Corneal abrasion
Patients presenting at one day post-operatively with a painful,
watery eye may have a corneal abrasion from intra-operative
trauma. The incidence is rare but is easily detectable from
well-defined corneal staining. This condition generally resolves
within a few days, but ocular comfort will be enhanced in
the short-term by insertion of a bandage contact lens.
Wound leak and suture complications
Leakage from the wound will occur following inadequate closure
of the incision, and is not uncommonly seen in large incision
surgery. However, this complication has become rare with the
advent of self-sealing small incision surgery.
Detection of wound leak is by performing the Seidel test.
After instillation of fluorescein and examination of the wound
under blue light, escaping aqueous will be seen diluting the
fluorescein at the site of leakage.
Very small leaks may seal spontaneously, although the precaution
of inserting a bandage contact lens for a week may be taken.
This approach becomes more necessary for marked leakage, where
there is a risk of hypotony, serious post-operative infection
or abnormal wound healing. Marked leakage may also need re-suturing.
The sutures themselves will cause discomfort to the patient
if the knots are not buried or if they are too tight. However,
little can be done at this stage until the wound has healed
after which the sutures may then be removed. Extreme cases
of poor suturing may require re-suturing. Inadequately buried
sutures and suture removal increase the risk of post-operative
endophthalmitis.8
Iris prolapse or incarceration of vitreous in the wound
Iris prolapse through the wound is seen rarely, especially
with the advent of self-sealing small incision surgery. However,
its presence should be looked for, especially following anterior
vitrectomy. Similarly, if vitreous has been lost during surgery,
examination must eliminate incarceration of vitreous in the
wound. In either event, excision of the trapped tissue is
essential to minimise the risk of chronic anterior uveitis,
defective wound healing, cystoid macular oedema and endophthalmitis.
Anterior chamber abnormalities
First day post-operative examination must ensure that the
anterior chamber is properly re-formed. A collapsed anterior
chamber requires immediate referral back to the surgeon for
remedial surgery.
Uveitis and adverse reactions to corticosteroids
Cells in the anterior chamber are expected post surgically,
and topical corticosteroids will have been given as a matter
of course. 5.6% of patients may have more advanced uveitis1,3.
This inflammation may be exacerbated by retained lens material,
which occurs in 1.1% of cases.1,3
If necessary, the corticosteroid starting dosage of four times
daily can be increased to six with more gradual reductions
under close supervision.
Some patients will respond to the corticosteroid therapy
with a raise in IOP. If this increase is evident after one
week, the steroids should be tailed-off more rapidly, providing
that the cellular activity in the anterior chamber has reduced
to acceptable levels. The patient will need to be reviewed
to ensure normalisation of IOP and no recurrence of inflammation.
A typical allergic response to the anti-inflammatory drops
may be seen in some patients, including peri-orbital swelling
and redness, chemosis, hyperaemia and watering. Often the
reaction is to Neomycin, where this is combined with a steroid,
and the problem can be overcome by exchanging the drops for
ones that only contain the steroid. Alternatively, steroids
in the form of minims may be prescribed when a reaction to
a preservative is suspected.
Displaced intraocular lens (IOL)
Within the first 24 hours of surgery, dilation or partial
dilation of the pupil is likely to persist following the mydriasis
of the day before. This facilitates examination of IOL position
(Figure 3). If
the IOL is malpositioned and not sufficiently centred on the
pupil, disturbing aberrations or edge glare may result (Figure
4). Remedial surgery will correct this if it cannot be
tolerated. Trauma, eye rubbing or capsular contraction may
be causes of subsequent IOL displacement.4
Total dislocation of the IOL into the vitreous may follow
intraoperative complications such as a capsular split. (It
may also occur later as a rare complication of Nd:YAG laser
capsulotomy.) The presence of the IOL in the vitreous cavity
increases the risk of cystoid macular oedema (CMO), but this
risk must be weighed against the risk of retinal detachment
if the IOL is removed. If the eye settles despite the presence
of the IOL in the vitreous, it may be left. A secondary AC-IOL
can then be considered (Figure
5).
Longer term complications of cataract surgery
Cystoid macular oedema
Cystoid macular oedema is an accumulation of fluid in the
outer plexiform and inner nuclear layers of the retina, centred
on the fovea. The incidence of CMO following phacoemulsification
cataract extraction is unknown, but 15 to 30% of extra-capsular
extractions show angiographic evidence of CMO. Of these, less
than 2% suffer visual deficit.4,5,9,10,11
CMO should be suspected in post-operative cataract patients
with reduced visual acuity and no other obvious cause. Without
the aid of fluorescein angiography, detection of mild CMO
is made by the experienced observer using biomicroscopy. Loss
of the foveal depression, thickening of the retina and multiple
fluid-filled microcysts at the fovea may be seen. Many patients
spontaneously improve (75% within 6 months4,9),
but if the CMO persists beyond 12 months, the microcysts will
have coalesced into large cystic spaces with subsequent formation
of a lamellar macular hole, causing permanent damage to central
vision.5,11,12
The exact cause of CMO is a topic of debate. Vitreous traction,
breakdown of the blood-aqueous and blood-retinal barriers,
and intraocular inflammation are all possibilities.4,5,13
Patients with diabetes mellitus are more at risk. Medical
treatment may include corticosteroids administered topically,
orally or by periocular posterior sub-Tenon’s injection, topical
and oral nonsteroidal agents, hyperbaric oxygen and oral acetazolamide.5,14
Endophthalmitis
Infectious post-operative endophthalmitis is a devastating
complication that is most feared by ophthalmic surgeons. It
may occur at any stage from within two days to a few months
of surgery. It occurs in 0.03 to 0.13% of extracapsular extraction
or phacoemulsification and IOL implantation cases, and 0.4%
of secondary lens implantation cases,5,6,8
although the risk has decreased with improvements in surgical
technique and wound closure. The infection is caused by various
organisms, the most common being Staphylococcus epidermidis.5
These may arise from the patient’s own ocular surface and
adnexa in blepharitis, conjunctivitis, canaliculitis or dacryocystitis,
contaminated solutions or instruments, or the environment
or personnel within the operating theatre. Prolonged surgery
(more than 60 minutes), vitreous loss and diabetes mellitus
are risk factors.
Early recognition and treatment are the key to a successful
outcome, although about 50% of cases will result in a blind
eye. Clinical signs and symptoms may include pain, marked
visual loss, hypopyon, corneal oedema, corneal infiltrate,
vitreous inflammation, retinitis, chemosis, conjunctival injection
and lid oedema (Figure
6). Other conditions can mimic infectious endophthalmitis,
such as severe anterior uveitis, often associated with retained
lens material, and toxic reactions to irrigating fluids or
the IOL. For a positive diagnosis of endophthalmitis, culture
samples from both the aqueous and vitreous are needed, although
organisms grow better from vitreous specimens because the
anterior chamber more effectively clears the bacteria.
Treatment includes intravitreal antibiotics, with possible
further administration of antibiotics by periocular injection,
topical and/or systemic therapy. Steroid therapy may be used
concurrently. Vitrectomy may be performed, producing better
penetration of the antibiotics, although this increases the
risk of retinal detachment.5,15
Retinal detachment
Approximately 0.1 to 0.2% of patients will experience a retinal
detachment within the first three months of uncomplicated
cataract surgery.1,3 Up to 2%
may go on to have a detachment in the future.5
The risk increases following posterior capsulotomy. Other
risk factors are retained lens material, vitreous loss, severe
myopia, lattice degeneration and trauma.5,16
As with any retinal detachment, proper management and early
detection will result in better visual prognosis.5
Posterior capsule opacification
Remnant or regenerated lens epithelial cells or fibres migrate
centrally to opacify the posterior capsule, resulting in reduced
visual acuity (Figure
7). This opacification is reported to occur in 5 to 50%
of adult patients, and nearly 100% of paediatric patients.5,17,18
The average time that posterior capsular opacification occurs
is 26 months post-operatively, with the time ranging from
three months to four years.5
Acrylic IOLs are thought to reduce the incidence as compared
to PMMA IOLs (see companion article in this issue on IOL design),
as are other factors such as atraumatic surgical technique,
thorough removal of cortical lens material and incorporation
of capsular bag fixation.5
Treatment of visually significant posterior capsular opacification
is by Nd:YAG capsulotomy (Figure
8). This procedure may cause pitting of the IOL. Other
complications are rare, but include an enhanced risk of retinal
detachment, transient rise in IOP, CMO, IOL dislocation in
plate haptic lenses, and vitreous prolapse into the anterior
chamber.
Unsatisfactory refractive error
In a recent USA review of medico-legal claims following cataract
surgery, the single largest group of claims involved insertion
of the wrong powered IOL.19
The commonest factors leading to these claims were incorrectly
labelled IOLs, the wrong IOL being handed to the surgeon in
theatre or errors in biometry. The result is an unsatisfactory
refractive outcome, which may be a source of great disappointment
to the patient, even in the presence of good visual acuity.
Extreme post-operative refractive surprises have been reduced
through enhanced theatre checking procedures, and improved
biometry techniques with modern IOL calculation formulae.
It is rare that the patient will return to the surgeon for
exchange of the IOL, but where this is necessary, the surgery
should be completed as close to the primary surgery as possible,
to minimise complications.
Conclusion
Serious complications from cataract surgery are rare with
modern surgical techniques. There is an increasing role opportunities
for non-medics to become involved in routine post-operative
cataract care. However, along with this opportunity comes
responsibility, and this article has sought to update and
inform the reader of the main complications, both minor and
major, that may occur, and the appropriate actions to be taken
should they do so.
|