The continued expansion of refractive surgery provision has necessarily led to increased shared care, albeit sometimes by default. Primary eye care for ophthalmic out-patients is usually provided by ophthalmologists, and conditions may be either an acute event or chronic diseases, such as diabetes or glaucoma in which long-term supervision in an out-patient environment is often required.
Other conditions, such as keratoconus, are largely supervised by optometrists prior to surgical intervention, though these patients straddle community and hospital care when the disease advances to the stage of penetrating keratoplasty.
Unfortunately, staffing levels are insufficiently supported in the HES and an attractive option is to delegate the management of chronic ophthalmic disease, or elective ophthalmic surgery follow-up, to groups such as community optometrists or other hospital-based paramedical personnel.
In theory, such shared care has much to commend it because of:
Delivery nearer the point of need.
More economical throughput of patients.
Reduced pressure on already overstretched hospital eye services.
Subsequent freeing up of services to enable quality provision of service to patients whose conditions can only be treated or supervised by ophthalmologists.
With talks continuing to try and make direct referral for cataract nationwide and with an increased input from the community optometrist, this article reviews the surgical procedures available and the professional involvement necessary for an effective service.
Sharing the management
In the UK and Australasia, the majority of cataracts referred to a public hospital system are initially identified by optometrists. There is, therefore, a key role, not only in identifying cataract, but also in referring appropriately.
Following surgery, many patients return to optometrists for ongoing eye care and spectacle provision. Of course, although modern phacoemulsification cataract surgery has fewer unexpected complications than earlier techniques, no surgery is free from complications, and patients may initially present with these to their own optometrists.
It is, therefore, incumbent on optometrists to be familiar with local criteria for referral and the expected outcome of cataract surgery, as well as a familiarity with common complications and their relative urgency in terms of management.
Although the majority of cataracts that will be identified by optometric review fall into the senile cataract category (Figure 1), a number of other aetiologies should be considered, particularly metabolic disorders such as diabetes (Figure 2), congenital or inherited cataract syndromes, toxic or drug-related cataract, such as steroid cataract, irradiation-induced (for example, infrared, X-rays, radiotherapy), and secondary cataract (for example, associated with uveitis).
It is also pertinent to take the family, occupational and medical history, particularly when cataract is identified in subjects less than 60 years of age. Of course, it must always be remembered that cataract does not occur in isolation, and may be associated with a number of systemic and ocular co-morbidities.
The Auckland Cataract Study (ACS),1 a prospective study of approximately 500 individuals undergoing cataract surgery in a public hospital service, highlights many of these associated conditions (Table 1). The timing of referral varies significantly with available healthcare funding and it is important that optometric professionals are cognisant of the local threshold for referral.
However, many would consider that when vision falls to around 6/12, the essential driving requirement in many countries, this should trigger the consideration of referral to the hospital services.
Other important factors must also be taken into account. For example, ocular symptoms like posterior subcapsular cataract may enable high contrast Snellen acuity of 6/6 yet produce intolerable glare, thus making driving difficult in a number of lighting conditions.
Other ocular diseases, that require regular review, such as diabetes, may also require earlier surgical intervention. Indeed, any assessment of cataract, and the need for cataract surgery should be holistic and take into account systemic disease, visual requirements for social and work activities, independence, physical mobility and driving demands.
Contemporary Small Incision Phacoemulsification
Cataract surgery, in the form of couching, has been around for more than 2,000 years, and extracapsular cataract surgery was popularised by Dr Jacques Daviel as long ago as the 1750s.
In the 20th century both intracapsular and extracapsular surgery were popular, with extracapsular surgery gaining the upper hand in the latter 25 years.
Interestingly, although Sir Harold Ridley inserted the first intraocular lens (IOL) in the middle of the century, insertion of intraocular lenses did not gain universal acceptance until 30 years later.
In the past 10 years, phacoemulsification (Figure 3) has become the predominant cataract technique in the developed world and with its emergence, IOLs have evolved from the original hard 6mm diameter PMMA designs, to foldable lenses of acrylic and silicone that pass through incisions of around 3mm.
Small incision phacoemulsification (97.5 per cent) with implantation of a foldable intraocular lens, under sub-Tenons local anaesthesia (95 per cent), has become the favoured phacoemulsification technique within Westernised societies. Usually a stepped or uniplanar, non-sutured wound, approximately 3.0-3.4mm wide, is used to facilitate phacoemulsification and IOL insertion.
Although sub-Tenons anaesthesia is becoming increasingly popular in New Zealand, the UK and elsewhere, a recent assessment of trends in cataract surgery,2 with respect to the US, Japan and Denmark, suggested that only ophthalmologists in Japan use predominantly sub-Tenons anaesthesia as frequently.
Usually, contemporary cataract surgery is performed under local or topical anaesthesia as a day case procedure.
In the ACS a higher proportion of clear corneal temporal incisions, than superior scleral tunnel incisions, was observed, highlighting local surgical preference.
However, Riley et al1 have shown that this elderly population exhibits a median refractive astigmatism of 1.2D that is against-the-rule in 50 per cent of eyes. Therefore, the choice of a temporal approach corneal incision may offer a minor beneficial effect on corneal astigmatism in appropriate cases.
In the ACS study, 76.7 per cent of subjects exhibited a 0.75D, or less, change in refractive astigmatism post small incision phacoemulsification.
Initial concerns that clear corneal incision might produce significantly greater astigmatism than scleral tunnel incisions seems unfounded.
Current techniques of clear corneal incisions produce similar astigmatic change to scleral tunnel incisions and, as noted previously, any such induced change may actually be beneficial in the older eye with against-the-rule astigmatism.
Intra-operative surgical complications
The design of the ACS, where reporting of intra-operative complications by the operating surgeons was followed by a comprehensive postoperative independent ophthalmic examination, may have advantages in terms of accuracy and consistency over comparable studies of self-reporting alone.
The observed rates of adverse surgical events are comparable to similar published studies, which have reported posterior capsular rupture rates of between 0 and 9.8 per cent of cases and clinically-apparent cystoid macular oedema in 0.6 to 6 per cent of eyes.
The overall posterior capsular rupture rate in the ACS study was 4.9 per cent, and there was no statistical difference between consultants and registrars.
However, assessment of complications by trainee surgeons of registrar grade in other large studies of phacoemulsification have highlighted an incidence of intra-operative posterior capsular rupture of up to 10 per cent. Interestingly, a Royal College of Ophthalmologists report, by Desai et al,3 noted a posterior capsule tear rate of 4.4 per cent in a National Cataract Study, whereas, more recently, Ionides et al,4 in a series of 1,420 cataract procedures noted a similar overall capsular rupture rate of 4.1 per cent in a major UK training hospital and in this series posterior capsule tears occurred in 5.3 per cent of cases performed by surgeons in training.
Intra-operative capsule rupture may be associated with subsequent malposition of the intraocular lens, vitreous in the anterior chamber or to the wound, and cystoid macular oedema. In the ACS, automated anterior vitrectomy was performed in 75 per cent of cases of capsule rupture and there was no clinical or statistical association between capsular tear and either cystoid macular oedema or a final best spectacle corrected visual acuity (BSCVA) of less than 6/12. In contrast, Ionides et al noted that eyes with a posterior capsule rupture were 3.8 times more likely to have a final BSCVA less than 6/12.
Day one: assessment post-phacoemulsification
A number of authors have debated the need for assessment on day-one post-phacoemulsification. However, it is still common practice and the day-one review can be very important in detecting problems, initiating treatment of elevated IOP and allaying patient fears.
Review should include symptoms, unaided vision (usually between 6/6 and 6/18) and pinhole or corrected vision, with an assessment of the cornea, pupil, intraocular lens position, media, and assessment of the macula.
In the ACS, review day-one post-phacoemulsification, identified a single case of early endophthalmitis, but no other sight-threatening adverse events. However, it is notable that 4.3 per cent of eyes had an IOP greater than 30mmHg.
Overall, nine eyes (1.9 per cent) required a suture for a wound leak. All these eyes had undergone temporal approach, clear-corneal, phacoemulsification, whereas no eyes with superior scleral tunnel approach demonstrated an aqueous humour leak. Although 16 per cent of corneal incisions were sutured intra-operatively, importantly, 2.4 per cent of corneal incisions required a suture to address wound leak on day one.
This suggests that perhaps a lower threshold for intra-operative placement of a suture, or a modification of wound architecture, should be observed in this population when clear-corneal, sutureless phacoemulsification surgery is performed.
However, this has to be balanced with the knowledge that all corneal sutures will require subsequent removal and 5.8 per cent of eyes in this study exhibited more than 1.0D of suture-induced astigmatism, which was statistically associated with BSCVA of less than 6/12 in almost half of these eyes.
Herbert et al,5 have recently highlighted the importance of day one review, noting 1.5 per cent of subjects with an IOP greater than 30mmHg, 0.26 per cent with painless iris prolapse and 1.8 per cent that required modification of the topical steroid regime.
All patients undergoing cataract surgery must be warned about rare, but devastating complications such as endophthalmitis and choroidal haemorrhage Ð which may result in loss of vision or even loss of the eye. Uncontrolled choroidal haemorrhage can result in expulsive haemorrhage of all intraocular contents, including vitreous and retina. Fortunately this is less common with phacoemulsification compared to extracapsular surgery.
Day 28: review and outcome
The majority of eyes have a stable refraction by four weeks post surgery. In the ACS, two-thirds of eyes achieved 6/12 unaided vision and 88 per cent of eyes achieved a BSCVA of 6/12 or better after cataract surgery. However, if those eyes that had a poor visual prognosis preoperatively, due to known co-existing ocular disease, are removed from analysis, the proportion with BSCVA of 6/12 or better rises to 94 per cent. But, while the mean postoperative BSCVA was 6/7.5 for all eyes in the study, special consideration should be given to those patients (1.5 per cent) who had lost lines of BSCVA, thought to be a consequence of the surgical intervention, at the latest follow-up. A longer follow-up period may show further improvement in those with cystoid macular oedema in which BSCVA was significantly adversely affected (1.3 per cent).
Only visual acuity and objective measures such as refraction have been reported in the ACS. However, additional measures such as functional acuity, symptom score and patient satisfaction are also valuable ways of providing a more comprehensive assessment of outcome following cataract surgery.
Indeed, the risk of dissatisfaction with outcome of cataract surgery is related to low visual acuity and age-related maculopathy in the better eye preoperatively, while, overall, the postoperative BSCVA in the operated eye is the single most important factor in terms of patient satisfaction.
Although phacoemulsification has a lower risk of retinal detachment than conventional extracapsular surgery, a series of 1,418 phacoemulsification procedures, with approximately one-third having undergone Nd.YAG laser capsulotomy, recorded a long-term risk of retinal detachment of 0.4 per cent.
Due to the limited follow-up, only to the point of outpatient discharge, longer-term complications, such as retinal detachment, or the requirement for Nd.YAG laser posterior capsulotomy, were not identified in the ACS prospective study.
References
1 Riley AF, Grupcheva CN, Malik TY et al. The Auckland Cataract study: demographic, corneal topographic and ocular biometric parameters. Clin Exp Ophthalmol, 2001; 29: 381-386.
2 Eggert T. Current trends in cataract surgery in Denmark Ð 1997 survey. Acta Ophthalmologica Scandinavica, 1998; 76, 6: 707.
3 Desai P, Minassian DC, Reidy A. National cataract surgery survey 1997-98: a report of the results of the clinical outcomes. Br JOphthalmol, Dec 1999; 83: 1336-1340.
4 Ionides A, Minassian D, Tuft S. Visual outcome following posterior capsule rupture during cataract surgery. Br J Ophthalmol, 2001; 85: 222-224.
5 Herbert EN, Gibbons H, Bell J et al. Complications of phacoemulsification on the first post-operative day: can follow-up be safely changed? JCataract Refract Surg, 1999; 25: 985-1003.
Charles McGhee is professor of ophthalmology at the University of AucklandThe continued expansion of refractive surgery provision has necessarily led to increased shared care, albeit sometimes by default. Primary eye care for ophthalmic out-patients is usually provided by ophthalmologists, and conditions may be either an acute event or chronic diseases, such as diabetes or glaucoma in which long-term supervision in an out-patient environment is often required.
Other conditions, such as keratoconus, are largely supervised by optometrists prior to surgical intervention, though these patients straddle community and hospital care when the disease advances to the stage of penetrating keratoplasty.
Unfortunately, staffing levels are insufficiently supported in the HES and an attractive option is to delegate the management of chronic ophthalmic disease, or elective ophthalmic surgery follow-up, to groups such as community optometrists or other hospital-based paramedical personnel.
In theory, such shared care has much to commend it because of:
Delivery nearer the point of need.
More economical throughput of patients.
Reduced pressure on already overstretched hospital eye services.
Subsequent freeing up of services to enable quality provision of service to patients whose conditions can only be treated or supervised by ophthalmologists.
With talks continuing to try and make direct referral for cataract nationwide and with an increased input from the community optometrist, this article reviews the surgical procedures available and the professional involvement necessary for an effective service.
Sharing the management
In the UK and Australasia, the majority of cataracts referred to a public hospital system are initially identified by optometrists. There is, therefore, a key role, not only in identifying cataract, but also in referring appropriately.
Following surgery, many patients return to optometrists for ongoing eye care and spectacle provision. Of course, although modern phacoemulsification cataract surgery has fewer unexpected complications than earlier techniques, no surgery is free from complications, and patients may initially present with these to their own optometrists.
It is, therefore, incumbent on optometrists to be familiar with local criteria for referral and the expected outcome of cataract surgery, as well as a familiarity with common complications and their relative urgency in terms of management.
Although the majority of cataracts that will be identified by optometric review fall into the senile cataract category (Figure 1), a number of other aetiologies should be considered, particularly metabolic disorders such as diabetes (Figure 2), congenital or inherited cataract syndromes, toxic or drug-related cataract, such as steroid cataract, irradiation-induced (for example, infrared, X-rays, radiotherapy), and secondary cataract (for example, associated with uveitis).
It is also pertinent to take the family, occupational and medical history, particularly when cataract is identified in subjects less than 60 years of age. Of course, it must always be remembered that cataract does not occur in isolation, and may be associated with a number of systemic and ocular co-morbidities.
The Auckland Cataract Study (ACS),1 a prospective study of approximately 500 individuals undergoing cataract surgery in a public hospital service, highlights many of these associated conditions (Table 1). The timing of referral varies significantly with available healthcare funding and it is important that optometric professionals are cognisant of the local threshold for referral.
However, many would consider that when vision falls to around 6/12, the essential driving requirement in many countries, this should trigger the consideration of referral to the hospital services.
Other important factors must also be taken into account. For example, ocular symptoms like posterior subcapsular cataract may enable high contrast Snellen acuity of 6/6 yet produce intolerable glare, thus making driving difficult in a number of lighting conditions.
Other ocular diseases, that require regular review, such as diabetes, may also require earlier surgical intervention. Indeed, any assessment of cataract, and the need for cataract surgery should be holistic and take into account systemic disease, visual requirements for social and work activities, independence, physical mobility and driving demands.
Contemporary Small Incision Phacoemulsification
Cataract surgery, in the form of couching, has been around for more than 2,000 years, and extracapsular cataract surgery was popularised by Dr Jacques Daviel as long ago as the 1750s.
In the 20th century both intracapsular and extracapsular surgery were popular, with extracapsular surgery gaining the upper hand in the latter 25 years.
Interestingly, although Sir Harold Ridley inserted the first intraocular lens (IOL) in the middle of the century, insertion of intraocular lenses did not gain universal acceptance until 30 years later.
In the past 10 years, phacoemulsification (Figure 3) has become the predominant cataract technique in the developed world and with its emergence, IOLs have evolved from the original hard 6mm diameter PMMA designs, to foldable lenses of acrylic and silicone that pass through incisions of around 3mm.
Small incision phacoemulsification (97.5 per cent) with implantation of a foldable intraocular lens, under sub-Tenons local anaesthesia (95 per cent), has become the favoured phacoemulsification technique within Westernised societies. Usually a stepped or uniplanar, non-sutured wound, approximately 3.0-3.4mm wide, is used to facilitate phacoemulsification and IOL insertion.
Although sub-Tenons anaesthesia is becoming increasingly popular in New Zealand, the UK and elsewhere, a recent assessment of trends in cataract surgery,2 with respect to the US, Japan and Denmark, suggested that only ophthalmologists in Japan use predominantly sub-Tenons anaesthesia as frequently.
Usually, contemporary cataract surgery is performed under local or topical anaesthesia as a day case procedure.
In the ACS a higher proportion of clear corneal temporal incisions, than superior scleral tunnel incisions, was observed, highlighting local surgical preference.
However, Riley et al1 have shown that this elderly population exhibits a median refractive astigmatism of 1.2D that is against-the-rule in 50 per cent of eyes. Therefore, the choice of a temporal approach corneal incision may offer a minor beneficial effect on corneal astigmatism in appropriate cases.
In the ACS study, 76.7 per cent of subjects exhibited a 0.75D, or less, change in refractive astigmatism post small incision phacoemulsification.
Initial concerns that clear corneal incision might produce significantly greater astigmatism than scleral tunnel incisions seems unfounded.
Current techniques of clear corneal incisions produce similar astigmatic change to scleral tunnel incisions and, as noted previously, any such induced change may actually be beneficial in the older eye with against-the-rule astigmatism.
Intra-operative surgical complications
The design of the ACS, where reporting of intra-operative complications by the operating surgeons was followed by a comprehensive postoperative independent ophthalmic examination, may have advantages in terms of accuracy and consistency over comparable studies of self-reporting alone.
The observed rates of adverse surgical events are comparable to similar published studies, which have reported posterior capsular rupture rates of between 0 and 9.8 per cent of cases and clinically-apparent cystoid macular oedema in 0.6 to 6 per cent of eyes.
The overall posterior capsular rupture rate in the ACS study was 4.9 per cent, and there was no statistical difference between consultants and registrars.
However, assessment of complications by trainee surgeons of registrar grade in other large studies of phacoemulsification have highlighted an incidence of intra-operative posterior capsular rupture of up to 10 per cent. Interestingly, a Royal College of Ophthalmologists report, by Desai et al,3 noted a posterior capsule tear rate of 4.4 per cent in a National Cataract Study, whereas, more recently, Ionides et al,4 in a series of 1,420 cataract procedures noted a similar overall capsular rupture rate of 4.1 per cent in a major UK training hospital and in this series posterior capsule tears occurred in 5.3 per cent of cases performed by surgeons in training.
Intra-operative capsule rupture may be associated with subsequent malposition of the intraocular lens, vitreous in the anterior chamber or to the wound, and cystoid macular oedema. In the ACS, automated anterior vitrectomy was performed in 75 per cent of cases of capsule rupture and there was no clinical or statistical association between capsular tear and either cystoid macular oedema or a final best spectacle corrected visual acuity (BSCVA) of less than 6/12. In contrast, Ionides et al noted that eyes with a posterior capsule rupture were 3.8 times more likely to have a final BSCVA less than 6/12.
Day one: assessment post-phacoemulsification
A number of authors have debated the need for assessment on day-one post-phacoemulsification. However, it is still common practice and the day-one review can be very important in detecting problems, initiating treatment of elevated IOP and allaying patient fears.
Review should include symptoms, unaided vision (usually between 6/6 and 6/18) and pinhole or corrected vision, with an assessment of the cornea, pupil, intraocular lens position, media, and assessment of the macula.
In the ACS, review day-one post-phacoemulsification, identified a single case of early endophthalmitis, but no other sight-threatening adverse events. However, it is notable that 4.3 per cent of eyes had an IOP greater than 30mmHg.
Overall, nine eyes (1.9 per cent) required a suture for a wound leak. All these eyes had undergone temporal approach, clear-corneal, phacoemulsification, whereas no eyes with superior scleral tunnel approach demonstrated an aqueous humour leak. Although 16 per cent of corneal incisions were sutured intra-operatively, importantly, 2.4 per cent of corneal incisions required a suture to address wound leak on day one.
This suggests that perhaps a lower threshold for intra-operative placement of a suture, or a modification of wound architecture, should be observed in this population when clear-corneal, sutureless phacoemulsification surgery is performed.
However, this has to be balanced with the knowledge that all corneal sutures will require subsequent removal and 5.8 per cent of eyes in this study exhibited more than 1.0D of suture-induced astigmatism, which was statistically associated with BSCVA of less than 6/12 in almost half of these eyes.
Herbert et al,5 have recently highlighted the importance of day one review, noting 1.5 per cent of subjects with an IOP greater than 30mmHg, 0.26 per cent with painless iris prolapse and 1.8 per cent that required modification of the topical steroid regime.
All patients undergoing cataract surgery must be warned about rare, but devastating complications such as endophthalmitis and choroidal haemorrhage Ð which may result in loss of vision or even loss of the eye. Uncontrolled choroidal haemorrhage can result in expulsive haemorrhage of all intraocular contents, including vitreous and retina. Fortunately this is less common with phacoemulsification compared to extracapsular surgery.
Day 28: review and outcome
The majority of eyes have a stable refraction by four weeks post surgery. In the ACS, two-thirds of eyes achieved 6/12 unaided vision and 88 per cent of eyes achieved a BSCVA of 6/12 or better after cataract surgery. However, if those eyes that had a poor visual prognosis preoperatively, due to known co-existing ocular disease, are removed from analysis, the proportion with BSCVA of 6/12 or better rises to 94 per cent. But, while the mean postoperative BSCVA was 6/7.5 for all eyes in the study, special consideration should be given to those patients (1.5 per cent) who had lost lines of BSCVA, thought to be a consequence of the surgical intervention, at the latest follow-up. A longer follow-up period may show further improvement in those with cystoid macular oedema in which BSCVA was significantly adversely affected (1.3 per cent).
Only visual acuity and objective measures such as refraction have been reported in the ACS. However, additional measures such as functional acuity, symptom score and patient satisfaction are also valuable ways of providing a more comprehensive assessment of outcome following cataract surgery.
Indeed, the risk of dissatisfaction with outcome of cataract surgery is related to low visual acuity and age-related maculopathy in the better eye preoperatively, while, overall, the postoperative BSCVA in the operated eye is the single most important factor in terms of patient satisfaction.
Although phacoemulsification has a lower risk of retinal detachment than conventional extracapsular surgery, a series of 1,418 phacoemulsification procedures, with approximately one-third having undergone Nd.YAG laser capsulotomy, recorded a long-term risk of retinal detachment of 0.4 per cent.
Due to the limited follow-up, only to the point of outpatient discharge, longer-term complications, such as retinal detachment, or the requirement for Nd.YAG laser posterior capsulotomy, were not identified in the ACS prospective study.
References
1 Riley AF, Grupcheva CN, Malik TY et al. The Auckland Cataract study: demographic, corneal topographic and ocular biometric parameters. Clin Exp Ophthalmol, 2001; 29: 381-386.
2 Eggert T. Current trends in cataract surgery in Denmark Ð 1997 survey. Acta Ophthalmologica Scandinavica, 1998; 76, 6: 707.
3 Desai P, Minassian DC, Reidy A. National cataract surgery survey 1997-98: a report of the results of the clinical outcomes. Br JOphthalmol, Dec 1999; 83: 1336-1340.
4 Ionides A, Minassian D, Tuft S. Visual outcome following posterior capsule rupture during cataract surgery. Br J Ophthalmol, 2001; 85: 222-224.
5 Herbert EN, Gibbons H, Bell J et al. Complications of phacoemulsification on the first post-operative day: can follow-up be safely changed? JCataract Refract Surg, 1999; 25: 985-1003.
Charles McGhee is professor of ophthalmology at the University of Auckland
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