HIGH-RISK Recognising ‘high-risk’ eyes before

Parikshit Gogate Mark Wood Head, Department of Paediatric Ophthalmology, Community Consultant Ophthalmologist, CCBRT Hospital, Care, HV Desai Eye Hospital, Pune 411028, India. Box 23310, Dar es Salaam, Tanzania. Email: [email protected] Email: [email protected]

Certain eyes are at a higher risk of compli- Conjunctivitis should be treated with cation during cataract surgery. Operations topical antibiotics prior to intraocular on such ‘high-risk’ eyes are also more likely surgery. to yield a poor visual outcome (defined as Noble Bruce best corrected vision less than 6/60 after Potential visualisation surgery).1 Learning to recognise when eyes are at problems during surgery greater risk, and acting accordingly, will help Corneal opacity you to avoid complications. Even so, before Leucoma-grade opacity will make your task the operation takes place, it is good practice Conjunctivitis extremely difficult. You will find it difficult to to explain to such patients that a poor see details, in particular the capsulotomy. outcome is a possibility. This makes these There may be residual lens matter • Measuring intraocular pressure. It is patients’ expectations more realistic and remaining in the bag, which will be difficult important to measure intraocular pressure improves postoperative compliance and to see. It will also be challenging to place in all patients, for example to identify follow-up. In most cases, patients who are the intraocular lens (IOL) in the posterior glaucoma. blind with complicated cataract will be chamber with both haptics under the iris. • A fundus examination. The fundus can happy with even a modest improvement of be seen through all but the densest Patients suffering from trachoma with their vision. cataracts. You can do a B-scan if the pannus, corneal dystrophy, degeneration, It is also important to have available all medium is not clear. and band-shaped keratopathy, have hazy the equipment you may need to manage a . Raised intraocular pressure may possible complication, for example a Your examination should be able to identify cause epithelial oedema. Phenylephrine machine in the case of capsular problems or signs which indicate that the dilating drops, if used too frequently, may rupture and vitreous loss. operation may not be straightforward. cause epithelial haze. Even minimal corneal Depending on where you are in the During the examination, you will need to handling during surgery may decrease world, certain ‘high-risk’ eyes will be more pay attention to the following areas, which corneal clarity. common: for example, pseudoexfoliation in are discussed in this article: Older patients, and those with Fuchs’ Somalia and India, onchocerciasis in • infection dystrophy, uveitis, or glaucoma, may have a Sudan, and angle-closure glaucoma in Asia. • potential visualisation problems compromised endothelium; their corneas You will get to know your local problems as • anatomy of the anterior segment may decompensate after surgery. The use of you perform more operations. • crystalline lens profiles high-viscosity viscoelastics, such as Healon • other health conditions. GV (sodium hyaluronate), and minimal Before you operate anterior chamber manipulations may help preserve the endothelium.2,3 It may be Get an accurate patient history. In particular, Infection advisable to perform extracapsular cataract obtain information on trauma, previous Any infection in or around the eye could lead extraction (ECCE), rather than phacoemulsi- operations, diabetes, dry eye, amblyopia, to endophthalmitis; infections should fication or manual small incision cataract and congenital abnormalities. If the patient therefore be treated before surgery. surgery (SICS).4 has only one eye, it is necessary to find out If there is a central corneal scar obscuring A blocked and infected lacrimal sac may what caused the loss of the other eye. the pupil, an optical sector may cause endophthalmitis. It is extremely Perform a thorough . be helpful. This should include: important to check the sac patency before surgery. If the sac has mucoid regurgitation, A small pupil • Measuring best corrected visual instil local antibiotic drops and postpone A small, rigid pupil poses a problem in both acuity. This will determine whether a surgery. A dacryocystectomy (DCT) or dacryo- ECCE and SICS. Any unnecessary manipu- potentially risky operation should be cystorhinostomy (DCR) may be done if lation of the iris can result in a small pupil. attempted or avoided. If the patient only antibiotics do not resolve the condition This will make it difficult to see residual lens has one eye, is the patient content with before surgery is to take place. his or her present vision? Be aware that matter, the position of the IOL, and the you could make it worse. Entropion, ectropion, and lagoph- • A slit lamp examination with dilated thalmos: these eyes may have corneal pupil. Many potential problems become exposure before and after surgery. visible when the pupil is dilated. A slit lamp Eyelashes rubbing on the eye are a source examination will identify most problems of infection. In such eyes, the postoperative you are liable to face during surgery, such use of steroids may precipitate a corneal Hogeweg Margreet as subluxated lenses. Check the maturity ulcer. In addition, lack of a proper lid closure of the lens, the condition of the capsule, mechanism will not allow the eye drops and whether the cataract really is the instilled to stay in the conjunctival sac. cause of the patient’s poor vision, before These three conditions need to be corrected deciding to perform a potentially risky by surgery before you can contemplate a Small pupil operation. cataract extraction.

Copyright © 2008 Parikshit Gogate and Mark Wood. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. anterior capsule for capsulotomy. However, the nucleus can be very large and Traumatic cataracts can give nasty A small pupil can be dealt with in the the chamber deep. A deep anterior chamber surprises. The following steps may help you following ways: may be caused by a ‘reverse pupil block’. In deal with them: this situation, the iris should be raised from • Intracameral phenylephrine can be tried • Do an ultrasound B-scan before surgery. the capsule to even out the pressure; the first. • There may be corneal or iris tears that chamber depth will then return to normal.5 • A Sinskey hook or Y-shaped IOL dialler can need to be repaired. Make a small incision Viscoelastics help to maintain anterior be used to stretch the pupillary sphincter. at the 12 o’clock position and use air or chamber depth where necessary and to The instruments are placed 180° apart viscoelastic to form the anterior chamber ease the insertion of instruments. The entry and the pupil stretched right out to the before suturing the . and exit of instruments should be kept to a limbus for ten seconds. • The anterior capsule may be broken or minimum. • If the pupil is still too small, a sphincter- torn. The tear can be extended as a CCC ectomy (three small radial cuts on the or an ‘envelope’ capsulotomy. sphincter pupillae, 120° apart) can be done Crystalline lens profiles • Keep the hydrodissection minimal, as there to facilitate nucleus delivery (Figure 1). The cataracts mentioned below will test a may be a posterior capsular tear. • Finally, iris hooks may be used to dilate surgeon’s skill, experience, and patience. In • If there is a posterior capsular tear, perform the pupil. ECCE, a capsular tension ring (CTR) can be dry aspiration under cover of viscoelastic. inserted after doing a continuous (complete) • Anterior vitrectomy is necessary if the If the surgeon is fastidious about having a circular capsulo rhexis (CCC) to stabilise the posterior capsule is torn. Try and preserve round pupil postoperatively, a small bag.6 Note that it is more important that the as much of the capsule as possible. peripheral iridectomy can be made and the CCC be ‘complete’ than it be ‘circular’, We normally do not put an IOL in at this cut extended to the pupillary margin (radial because an intact capsular margin ensures stage, but rather do this as a secondary iridotomy). The iridotomy can be sutured that the zonular tension is equally divided all procedure. later using 10-0 Prolene interrupted sutures around. Keep hydrodissection to a (Figure 2); this procedure demands consid- Membranous cataract occurs when the minimum. If you are using phacoemulsifi- erable skill and patience. However, this is lens matter has been absorbed and the cation, do it ‘in the bag’. If you are using not often required. anterior and posterior capsules fuse. ECCE or SICS, gently rotate the nucleus into A capsulotomy, possibly followed by an the anterior chamber (do not tumble) and Figure 1: Figure 2: Radial anterior vitrectomy, should clear the opacity. then deliver it outside the incision. All are Sphincterotomy for iridotomy Leave enough capsule to support an IOL. difficult procedures. It may be easier to a small, rigid pupil: sutured with This IOL will have to be placed in the sulcus. three cuts made 10.0 interrupted remove the lens (possible intracapsular 120° apart sutures extraction with vectis loop or lensectomy) and implant an anterior chamber lens. • Hard, dense nuclei are difficult to remove with or SICS. You may prefer to do a routine extracap- sular extraction.4 • Hypermature cataracts have a small

nucleus and a wrinkled capsule. Anterior (http://drsobol.com) Sobol Aaron capsulotomy may be difficult. • Milky cataract (Morganian): when Uveitis Anatomy of the anterior making the capsulotomy, the ‘milk’ from the cataract fills the anterior chamber, Uveitis causes synechiae and cataract. segment obscuring the surgeon’s view. The anterior Posterior synechiae can be gently separated Narrow anterior chambers capsulotomy may not be complete. Filling using an iris repositor after instilling visco- These eyes make it difficult to perform the anterior chamber with viscoelastic elastic. This will probably mean that you will intraocular manipulations and to move the before starting the capsulotomy may help. perform a ‘can-opener’ capsulotomy. The instruments in and out of the eye. This • Fibrotic anterior capsule: these very sphincter pupillae may still need to be increases chances of iris injury and irido- thick, tough capsules may have to be cut stretched. Keep iris handling to a minimum dialysis at the iris root (the thinnest part of with scissors. in cases of uveitis, at it may trigger postoper- the iris) and at its major arterial circle. A narrow • Pseudoexfoliation causes weak zonules ative inflammation. It is advisable to start oral chamber occurs in hypermetropic eyes, while and glaucoma. There is an increased and local steroids a few days before surgery. deep anterior chambers occur in high myopes. chance of zonular dialysis. • A subluxated or dislocated lens can High ametropia occur in many conditions: very mature Other health conditions High hypermetropia or myopia create lenses, pseudoexfoliation, trauma, Glaucoma: specific problems. Marfan’s syndrome, and other • Eyes with long-standing glaucoma have The surgeon must re-check the A-scan syndromes. poor endothelial cell counts; postoperative and keratometer findings of IOL power, as corneal oedema may occur. errors are common in high myopia and high • Eyes that have been treated for many years hypermetropia. It is worth trying to do a with anti-glaucoma agents, like pilocarpine, refraction to help assess the A-scan readings. Noble Bruce may have pupils resistant to dilation. Very dense and mature cataracts can give • Complications like iris injury, capsular tear erroneous readings. When in doubt, it is and zonular dialysis can all aggravate better to veer on the side of slight myopia pre-existing glaucoma. postoperatively. Most patients prefer to see • Previous means that the clearly in the medium-to-near distance functioning bleb must be preserved during Dislocated without spectacle correction. cataract surgery, by using either a corneal lens after Highly myopic patients have a wide incision (phacoemulsification) or a trauma angle, which facilitates instrument entry. Continues overleaf ➤

Community Eye Health Journal | Vol 21 ISSUE 65 | MARCH 2008 13 HIGH-RISK EYES Continued HOW TO

temporal approach. To complicate matters, synechiae and a shallow anterior chamber are often present. Administering an eye anaesthetic: principles, techniques, and complications

HIV-positive patients: cataract surgery in these patients requires routine (and thus proper) care. However, such patients may Ahmed Fahmi Richard Bowman have posterior segment complications such Paediatric Ophthalmology Ophthalmologist, CCBRT Disability Hospital, as cytomegalovirus (CMV) retinitis, vasculitis, Fellow, CCBRT Disability Tanzania; Honorary Senior Lecturer, London and choroiditis, which may not be evident in Hospital, Tanzania. School of Hygiene and Tropical Medicine. a white cataract. Performing a B-scan may Email: [email protected] Email: [email protected] not always be helpful, but it should be done when fundus details are not clear. These Rationale patients are also prone to secondary infection. The trigeminal nerve carries the sensory innervation of the eye and adnexa in three divisions: ophthalmic, maxillary, and mandibular. The sensory fibres of the eye and Diabetes: it is important to try and keep adnexa are found in the ophthalmic division – with the exception of a portion of the the posterior capsule intact. Retinopathy sensory input from the lower lid, which is carried by the maxillary division. Blocking the progresses more rapidly in diabetic patients sensory fibres providesanaesthesia so that no pain is felt. after cataract surgery and a ruptured The motor supply of the extraocular muscles and levator palpebrae superioris is capsule can be a factor in rubeosis. Close carried by the oculomotor (III), trochlear (IV), and abducens (VI) nerves. Paralysing follow-up and timely laser treatment are these muscles by blocking their motor supply provides akinesia so that the eye does required. If possible, treat the retinopathy not move during surgery. preoperatively with laser. The motor supply of the orbicularis oculi, which is responsible for the gentle and forcible closure of the eye, is carried by the facial nerve (VII). Blocking these fibres will Onchocerciasis: this disease affects the provide better surgical exposure. It also reduces the risk of forcing out the ocular contents cornea, uvea, and retina. In endemic if the patient tries to close his forcibly after the surgeon opens the globe. areas, cataract surgery can be disappointing due to optic nerve and retinal pathology. You must take care when selecting patients Anatomy for cataract surgery, in order to avoid performing operations which will bring no It is important to recall the anatomy and to have a precise knowledge of the various benefit to patients. injection sites for the anaesthetic. The anteroposterior diameter of the globe averages 24.15 mm (range: 21.7 to 28.75 mm). The axial length of myopic eyes are at the Hypertension and high positive pressure upper end of this range. This increases the risk of globe perforation, especially with a during surgery: in general, it is important retrobulbar block. The length of the bony orbit is about 40 to 45 mm. On average, the to avoid a high positive pressure during surgery. anatomic equator is about 13 to 14 mm behind the limbus along the surface of the This can be caused by an inadequate or globe. At its closest distance to the bony orbit, the globe is about 4 mm from the excessive peribulbar block, or a tight bridle roof, 4.5 mm from the lateral wall, 6.5 mm from the medial wall, and 6.8 mm from suture. It is therefore important to control the floor. hypertension in patients. In addition, retrob- The retrobulbar space lies inside the extraocular muscle cone, behind the globe. ulbar haemorrhage should be identified early Relatively avascular areas of the orbit are confined to the anterior orbit in the lower and the operation postponed. Expulsive outer (inferotemporal) and upper outer (superotemporal) quadrants. The superonasal haemorrhage in one eye could alert you to quadrant is highly vascular and has limited space. possible problems in the second eye. Tenon’s capsule is the anterior extension of the visceral layer of dura investing the optic nerve. Therefore, the sub-Tenon’s space is continuous with the subdural space Asthma, chronic obstructive pulmonary and is, in effect, an anatomical pathway from the limbus to the retrobulbar space. disease and constipation: when in doubt Because the conjunctiva fuses with Tenon’s capsule 2 to 3 mm behind the limbus, the about whether to suture the wound, it is sub-Tenon’s space can be accessed easily through a scissor snip made there. always better to do so – especially in patients suffering from these conditions.

References Choosing the anaesthesia technique 1 Limburg H. Monitoring cataract surgical outcomes: methods and tools. Community Eye Health J 2002; Decide in advance what technique you are going to use. A retrobulbar block is more 15(44): 51–3. 2 Gogate PM, Kulkarni SR, Krishnaiah S, Deshpande RD, efficient in producing anaesthesia and akinesia and has a faster onset of action. Joshi SA, Palimkar A et al. Safety and efficacy of However, it carries a higher risk of rare, yet serious, complications, such as globe phacoemulsification compared with manual small perforation, retrobulbar haemorrhage, and injection of the anaesthetic into the incision cataract surgery by a randomised controlled clinical trial: six weeks results. Ophthalmology cerebrospinal fluid (CSF). Mastering the technique reduces these risks significantly. 2005;112: 869–874. The probability of complications is reduced in a peribulbar block; however, this 3 Basti S, Vasavada AR, Thomas R, Padmanabhan P. technique is slower and less efficient, it carries a higher risk of potential chemosis, Extracapsular cataract extraction: Surgical techniques. Indian Journal of Ophthalmology 1993;41: 195–210. and it puts more pressure on the eye. A retrobulbar block should be avoided if the axial 4 Bourne RR, Minassian DC, Dart JK et al. Effect of cataract length of the eye is greater than 27 mm. surgery on the corneal endothelium: modern phaco- emulsification compared with extra capsular cataract When a retrobulbar or peribulbar block is unsatisfactory, you can add a sub-Tenon’s surgery. Ophthalmology 2004;111(4): 679–85. block; it is a suitable supplement. By itself, the sub-Tenon’s block is useful for 5 Cionni RJ, Barros MG, Osher RH. Management of shorter procedures, provided you are operating on cooperative patients. The lens-iris diaphragm retropulsion syndrome during phacoemulsification. J Cataract & Refract Surg 2004; sub-Tenon’s block is more likely to be performed by an ophthalmic surgeon than 30: 953–956. by an ophthalmic anaesthetist. It enables top-up injections to be easily and safely 6 Ahmed IK, Cionni RJ, Kranemann C, Crandall AS. given. Sub-Tenon’s blocks are less likely to cause systemic complications than Optimal timing of capsular tension ring implantation: 1 Miyake-Apple video analysis. J Cataract & Refract Surg retrobulbar or peribulbar blocks. 2005;31: 1809–1813.

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