Key Features
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Diversity of techniques for optimal cataract patient outcomes.
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Intracapsular cataract extraction or large-incision full lens extraction.
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Extracapsular cataract extraction or large-incision nucleus expression cataract surgery.
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Small-incision manual nucleus expression lens surgery (“mininuc” technique).
Introduction
The techniques of manual cataract surgery remain invaluable in the management of certain crystalline lens and zonular pathologies inappropriate for phacoemulsification (“phaco”).
The decision regarding the choice of procedure is based on a spectrum of factors related to the socioeconomic environment (equipment availability) and the operative experience (surgeon and team) on the one hand and to the ophthalmological condition of the patient on the other.
Historical Issues
Manual cataract surgery techniques (initially intracapsular cataract extraction [ICCE] followed by extracapsular cataract extraction [ECCE]) have been the mainstay of cataract surgery for the majority of the last century. Much of the value of the manual techniques has been the lower costs and minimal instrumentation with which the surgery can be performed. These techniques provide excellent rehabilitation of blindness caused by cataract at the expense of only recovery time and stability of refraction over the first year.
ICCE held favor over ECCE in view of the latter’s potential for complications (inflammation, iritis, phacoanaphylaxis, secondary membranes, glaucoma ) until the 1950s. The development of systems that provided simultaneous irrigation while aspirating was the key to the return of the extracapsular systems. These systems allowed for better removal of lenticular material (ECCE). These principles reached a high level of technological sophistication (and expense) in the phaco techniques. The attempts at cost containment led to the development of manual nucleus expression surgery through smaller incisions, or the so-called mininuc technique.
Historical Issues
Manual cataract surgery techniques (initially intracapsular cataract extraction [ICCE] followed by extracapsular cataract extraction [ECCE]) have been the mainstay of cataract surgery for the majority of the last century. Much of the value of the manual techniques has been the lower costs and minimal instrumentation with which the surgery can be performed. These techniques provide excellent rehabilitation of blindness caused by cataract at the expense of only recovery time and stability of refraction over the first year.
ICCE held favor over ECCE in view of the latter’s potential for complications (inflammation, iritis, phacoanaphylaxis, secondary membranes, glaucoma ) until the 1950s. The development of systems that provided simultaneous irrigation while aspirating was the key to the return of the extracapsular systems. These systems allowed for better removal of lenticular material (ECCE). These principles reached a high level of technological sophistication (and expense) in the phaco techniques. The attempts at cost containment led to the development of manual nucleus expression surgery through smaller incisions, or the so-called mininuc technique.
Manual (Large-Incision) Cataract Surgery
These techniques require strict attention to wound construction for optimal optical outcome.
Incision
An incision of 8–12 mm of arc length around the limbus (corneal, limbal, scleral, or a combination of all) is required to manually express the nucleus from the capsular bag in ECCE, whereas an incision of 12–14 mm around the limbus is required in ICCE. Variation in the incision position has a profound influence on the postoperative occurrence of cylindrical error. The more corneal the section is placed, the stronger is the influence on the cylindrical error. The more scleral the section is placed, the less is the cylindrical induction, particularly if a three-plane ( Fig. 5.12.1 ), valve-type incision is utilized. Combinations of both scleral and corneal sections can be used to correct pre-existing cylindrical errors. These sections can be rotated appropriately to reduce cylindrical error in any meridian.
When the incision is fashioned, the third plane of the incision (see Fig. 5.12.1 ) should be completed only when the anterior capsulectomy has been performed. This allows the anterior chamber to maintain depth, with or without viscoelastic material, while the anterior capsulectomy is undertaken. Once this is done, the internal incision may be completed.
Wound Closure
During closure of a wound cut in the three-plane format, the sutures must not be overtightened; the edges are merely opposed (incisional gape) (see Fig. 5.12.1 ). The valve effect of the incision seals the wound. In cases in which leakage is excessive, closure can be obtained by intracameral air.
Further opportunity for cylinder modification arises when sutures are removed. This allows controlled dehiscence of the wound. Dehiscence induces negative cylindrical effect at the meridian of the suture removal. A rough guide to timing suture removal is as follows:
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After 1 month, if major wound dehiscence is required to correct cylindrical error (3–6 diopters).
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After 2 months, if minor dehiscence is required to correct cylindrical error (2–3 diopters).
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At 3–6 months, to resume preoperative cylinder.
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After 6 months, to maintain surgically induced cylinder correction, if appropriate.
Incision
An incision of 8–12 mm of arc length around the limbus (corneal, limbal, scleral, or a combination of all) is required to manually express the nucleus from the capsular bag in ECCE, whereas an incision of 12–14 mm around the limbus is required in ICCE. Variation in the incision position has a profound influence on the postoperative occurrence of cylindrical error. The more corneal the section is placed, the stronger is the influence on the cylindrical error. The more scleral the section is placed, the less is the cylindrical induction, particularly if a three-plane ( Fig. 5.12.1 ), valve-type incision is utilized. Combinations of both scleral and corneal sections can be used to correct pre-existing cylindrical errors. These sections can be rotated appropriately to reduce cylindrical error in any meridian.
When the incision is fashioned, the third plane of the incision (see Fig. 5.12.1 ) should be completed only when the anterior capsulectomy has been performed. This allows the anterior chamber to maintain depth, with or without viscoelastic material, while the anterior capsulectomy is undertaken. Once this is done, the internal incision may be completed.
Wound Closure
During closure of a wound cut in the three-plane format, the sutures must not be overtightened; the edges are merely opposed (incisional gape) (see Fig. 5.12.1 ). The valve effect of the incision seals the wound. In cases in which leakage is excessive, closure can be obtained by intracameral air.
Further opportunity for cylinder modification arises when sutures are removed. This allows controlled dehiscence of the wound. Dehiscence induces negative cylindrical effect at the meridian of the suture removal. A rough guide to timing suture removal is as follows:
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After 1 month, if major wound dehiscence is required to correct cylindrical error (3–6 diopters).
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After 2 months, if minor dehiscence is required to correct cylindrical error (2–3 diopters).
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At 3–6 months, to resume preoperative cylinder.
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After 6 months, to maintain surgically induced cylinder correction, if appropriate.
Intracapsular Cataract Extraction
General Comments
Currently, the need for ICCE is restricted to the need for removal of the entire crystalline lens. This is necessary when the zonulear fibers are no longer present or when they are of insufficient strength to withstand the phaco process or to provide adequate stability for an intraocular lens.
Zonular dissolution, an essential step in the past, is thus unnecessary for today’s indications for ICCE. The cryophake (tip freeze adherence driven by gaseous expansion) remains the most valuable tool for ICCE ( Fig. 5.12.2 ).
Specific Techniques
Iris Management
Full pupillary dilation is necessary for the lens to pass through. Posterior synechiae may need division or a miotic pupil may need stretching, but invariably the pupil is sufficiently elastic to permit passage of the lens. A small peripheral iridectomy should be cut at some stage in the procedure to avoid pupil block. Occasionally, a radial iridotomy (from peripheral iridotomy to pupil margin) is necessary for access to the lens surface for cryo-application and optimal “ice ball” formation. It is important to have a dry lens bed, free of both iris and cornea, for safe removal of the lens without collateral damage. (An assistant elevating the cornea with traction on a suture placed in mid-incision [incision as described above] will free the surgeon’s nondominant hand to dry the lens and move the iris away with a microswab and operate the cryoprobe with the dominant hand to apply the “ice ball” and appropriate swaying traction to remove the lens.)
Vitreous Presentation or Prolapse
After careful removal of the lens, the vitreous face is likely to remain intact if unnecessary globe pressure is avoided. Should vitreous emerge from the entry wound, proper excision is necessary to avoid any vitreous traction syndrome. Vitrectomy may be necessary, depending on the intraocular lens of choice. Identification of prolapsed vitreous will be enhanced by injection of particulate triamcinolone.
Intraocular Lenses
Because the capsular bag has been removed, the choice of intraocular lens (IOL) support is limited to the angle, iris, or ciliary sulcus (fixated by suture). This should be done with ophthalmic viscosurgical device (OVD) protection.
An angle-supported lens must be fitted carefully to the individual chamber diameter so that it neither distorts nor moves for endothelial protection. An iris-supported lens, either anteriorly or posteriorly fixed, provides safe optical rehabilitation when adequate iris is available. Ciliary sulcus lens placement requires transscleral support by suture fixation and is useful when there is either iris damage (e.g., from trauma) or trabecular damage (e.g., associated with glaucoma). Adequate vitreous clearance is a prerequisite in the case of all of these placement sites, particularly with ciliary sulcus fixation.
General Comments
Currently, the need for ICCE is restricted to the need for removal of the entire crystalline lens. This is necessary when the zonulear fibers are no longer present or when they are of insufficient strength to withstand the phaco process or to provide adequate stability for an intraocular lens.
Zonular dissolution, an essential step in the past, is thus unnecessary for today’s indications for ICCE. The cryophake (tip freeze adherence driven by gaseous expansion) remains the most valuable tool for ICCE ( Fig. 5.12.2 ).
Specific Techniques
Iris Management
Full pupillary dilation is necessary for the lens to pass through. Posterior synechiae may need division or a miotic pupil may need stretching, but invariably the pupil is sufficiently elastic to permit passage of the lens. A small peripheral iridectomy should be cut at some stage in the procedure to avoid pupil block. Occasionally, a radial iridotomy (from peripheral iridotomy to pupil margin) is necessary for access to the lens surface for cryo-application and optimal “ice ball” formation. It is important to have a dry lens bed, free of both iris and cornea, for safe removal of the lens without collateral damage. (An assistant elevating the cornea with traction on a suture placed in mid-incision [incision as described above] will free the surgeon’s nondominant hand to dry the lens and move the iris away with a microswab and operate the cryoprobe with the dominant hand to apply the “ice ball” and appropriate swaying traction to remove the lens.)
Vitreous Presentation or Prolapse
After careful removal of the lens, the vitreous face is likely to remain intact if unnecessary globe pressure is avoided. Should vitreous emerge from the entry wound, proper excision is necessary to avoid any vitreous traction syndrome. Vitrectomy may be necessary, depending on the intraocular lens of choice. Identification of prolapsed vitreous will be enhanced by injection of particulate triamcinolone.
Intraocular Lenses
Because the capsular bag has been removed, the choice of intraocular lens (IOL) support is limited to the angle, iris, or ciliary sulcus (fixated by suture). This should be done with ophthalmic viscosurgical device (OVD) protection.
An angle-supported lens must be fitted carefully to the individual chamber diameter so that it neither distorts nor moves for endothelial protection. An iris-supported lens, either anteriorly or posteriorly fixed, provides safe optical rehabilitation when adequate iris is available. Ciliary sulcus lens placement requires transscleral support by suture fixation and is useful when there is either iris damage (e.g., from trauma) or trabecular damage (e.g., associated with glaucoma). Adequate vitreous clearance is a prerequisite in the case of all of these placement sites, particularly with ciliary sulcus fixation.
Iris Management
Full pupillary dilation is necessary for the lens to pass through. Posterior synechiae may need division or a miotic pupil may need stretching, but invariably the pupil is sufficiently elastic to permit passage of the lens. A small peripheral iridectomy should be cut at some stage in the procedure to avoid pupil block. Occasionally, a radial iridotomy (from peripheral iridotomy to pupil margin) is necessary for access to the lens surface for cryo-application and optimal “ice ball” formation. It is important to have a dry lens bed, free of both iris and cornea, for safe removal of the lens without collateral damage. (An assistant elevating the cornea with traction on a suture placed in mid-incision [incision as described above] will free the surgeon’s nondominant hand to dry the lens and move the iris away with a microswab and operate the cryoprobe with the dominant hand to apply the “ice ball” and appropriate swaying traction to remove the lens.)
Vitreous Presentation or Prolapse
After careful removal of the lens, the vitreous face is likely to remain intact if unnecessary globe pressure is avoided. Should vitreous emerge from the entry wound, proper excision is necessary to avoid any vitreous traction syndrome. Vitrectomy may be necessary, depending on the intraocular lens of choice. Identification of prolapsed vitreous will be enhanced by injection of particulate triamcinolone.
Intraocular Lenses
Because the capsular bag has been removed, the choice of intraocular lens (IOL) support is limited to the angle, iris, or ciliary sulcus (fixated by suture). This should be done with ophthalmic viscosurgical device (OVD) protection.
An angle-supported lens must be fitted carefully to the individual chamber diameter so that it neither distorts nor moves for endothelial protection. An iris-supported lens, either anteriorly or posteriorly fixed, provides safe optical rehabilitation when adequate iris is available. Ciliary sulcus lens placement requires transscleral support by suture fixation and is useful when there is either iris damage (e.g., from trauma) or trabecular damage (e.g., associated with glaucoma). Adequate vitreous clearance is a prerequisite in the case of all of these placement sites, particularly with ciliary sulcus fixation.
Extracapsular Cataract Extraction
Extracapsular surgery entails more steps compared with intracapsular surgery in that the capsular bag is left in the eye, held in position by zonular fibers. To initiate the process, a hole is made in the crystalline lens in a central position in the visual axis (anterior capsulectomy). The remainder of the process involves careful removal of the contents.
Anterior Capsulectomy
The techniques of anterior capsulectomy have changed over the past 30 years.
“Can Opener” Capsulectomy
The simplest type of capsular opening or capsulectomy is the “can opener” type, in which a number of very close, pinpoint perforations are created in a central, circular tract in the anterior capsule. Centripetal traction is placed on the central piece of capsule to create a tear along the perforations. The loose piece is then carefully removed. One advantage of this technique is the relative accuracy that can be achieved when visibility is poor (e.g., for a dense cataract with a poor red reflex or a very small pupil that requires the perforations to be made under the pupillary margin).
Linear Capsulectomy and Intercapsular Techniques
Linear capsulectomy techniques enable external expression while the anterior capsule is utilized to protect the corneal endothelium. In this method, a curvilinear incision is made in the upper third of the anterior lens capsule to create a slit or envelope opening into the lens capsular bag. After nucleus mobilization and expression and cortical material removal, the IOL can be inserted into the remaining capsular bag. The capsulectomy is completed by performing a continuous curvilinear capsulorrhexis across the remaining capsule to complete the circular central opening.
Capsulorrhexis
Capsulorrhexis, or continuous curvilinear capsulectomy, is a quick and, once learned, easy technique for anterior capsule removal. It provides the best security for the IOL within the capsular bag. The initial capsulotomy can be made centrally with a cystotome, or bent needle, or by utilizing the tip of a fine capsulorrhexis forceps. Once the capsule has been opened, a piece of anterior capsule is grasped and torn in a circular manner, with continuous change of the tearing vectors to achieve the round opening (capsulectomy) in the anterior capsule.
Size, Type, and Position of Capsulectomy
The capsulectomy needs to be large enough for the passage of the nucleus. The size of the nucleus is age dependent but can be modified by hydrodissection and hydrodelineation using an appropriate cannula. If the nucleus is deemed too big for passage through the capsulectomy (e.g., after an unsuccessful hydrodelineation or after too small an initial capsulorrhexis), relaxing incisions in the capsulorrhexis are necessary to reduce the possibility of capsular dislocation and zonular damage during nucleus expression. During hydrodissection, if the anterior capsular opening is large enough, part of the equatorial rim of the nucleus can be expressed into the anterior chamber, then rotated into the anterior chamber and into the incision, and thus removed from the eye. OVD material between the corneal endothelial surface and the nuclear surface is necessary to prevent endothelial damage.
The size and shape of the capsulorrhexis can be varied by the surgeon. A large capsulectomy facilitates surgery, but when this exceeds approximately 6.5 mm in diameter, the capsulorrhexis becomes difficult to control because of the presence of the insertion of the zonules. When the anterior capsular ridge is crossed, the danger of a peripheral radial irretrievable split is possible (particularly if the anterior chamber is not kept deep; a shallow anterior chamber creates tension on the anterior zonular ligament). Peripheral splits are usually blocked by the zonular fibers, but unwanted posterior capsular tears may be caused by this mechanism.
Nucleus Expression
The scleral lip of the incision should be depressed to allow the leading pole of the nucleus to present into the incision. Gentle pressure at the 180° opposing limbus then expresses the nucleus. The appropriate pressure may be applied with a broad-based instrument, such as a vectis or squint hook.
Alternatively, internal expression with the use of an irrigating vectis is effective, as long as the nucleus has undergone hydrodissection and partial hydroexpression. The space between the nucleus and the posterior capsule or cortex is opened with the irrigation function of the vectis. Viscoelastic material also is useful in defining and holding these spaces and in preventing posterior capsular and endothelial damage.
Cortical Washout
The remaining cortex is removed using an irrigation–aspiration technique. The tip of the irrigation–aspiration cannula (Simcoe) should be kept in view to avoid unwanted capsular engagement. Difficulties can arise if the globe pressure causes the anterior chamber to become shallow, closing the fornix of the capsular bag. Partial closure of the wound and irrigation produces a deep and safe anterior chamber within which to work. Cleaning of the posterior capsule and removal of remaining resistant cortical remnants can be achieved by aspiration using a fine cannula with a polished tip.
Intraocular Lens Insertion
Insertion of the IOL is performed under direct vision, with the second haptic inserted either by circular dialing of the IOL or by direct placement with the use of fine forceps. When the capsular bag is damaged by complication, the sites of IOL placement become the same as those noted in the ICCE section. In some circumstances where sufficient capsular support still exists in spite of capsular damage, posterior chamber implantation can be considered (ciliary sulcus placement).
Mininuc Technique
Anterior Chamber Maintainer
An anterior chamber maintainer (ACM) ( Fig. 5.12.3 ) is inserted through the clear cornea to the anterior chamber between the 4 o’clock and 8 o’clock positions, parallel to and near the limbus. The height of the infusion bottle determines the intraocular pressure (IOP). The continuous flow is responsible for the anterior chamber maintenance system.
