Fig. 12.1
Total cataract
Dense opacity located at the center of the lens with a diameter ≥ 3 mm (Fig. 12.2), including dense nuclear opacity and posterior subcapsular opacity.
Fig. 12.2
Dense central cataracts. (a) Red reflex is blocked by the central opacity in retroillumination; (b) dense nuclear opacity; (c) dense posterior subcapsular opacity in the center
The opacity located near the posterior pole of the refractive system (Fig. 12.3): surgeries are required even if its diameter is less than 3 mm.
Fig. 12.3
Posterior polar opacity
Strabismus, loss of central fixation, or nystagmus in the affected eye, indicating the presence of significant visual deprivation: immediate surgeries are necessary.
Any systemic conditions that may affect anesthesia are contraindicative.
12.1.2 Timing of Surgery
The visual system is still developing in the infant period, but there is a latent period after birth, which means visual deprivation has minimal effect on visual development; thereafter, a sensitive period begins and lasts until 7–8 years old, during which time even mild visual impairment will influence visual development [3–7]. Therefore, if cataract surgery is indicated, the operation should be performed before the onset of the sensitive period, so as to minimize the detrimental effect on visual outcome. It has been shown that unilateral and bilateral visual deprivation has different effects on visual development. In full-term infants with unilateral cataract, the latent period of visual development typically lasts until 6 weeks after birth [8]. Therefore, for these patients with unilateral dense cataract, performing the operation at 4–6 weeks of age may not only avoid the highest surgical risk at 1 month postnatal but also effectively solve the visual impairment problem before the onset of the sensitive period. It is more difficult to define the latent period for infants with bilateral dense cataract. Lambert and colleagues reported that in these patients, the visual outcomes are generally poor when surgery was postponed after 10 weeks postnatal [9]. Thus, it is recommended that the surgery be performed before 10 weeks in children with bilateral dense cataracts.
However, it remains controversial, regarding the indications and timing of pediatric cataract surgery, and further study is warranted. Thus, multicenter, large-scale, randomized controlled clinical trials may be worthy of consideration in the future.
12.2 Incision Construction
Principles of incision construction in pediatric cataract surgery include minimizing injury to ocular tissues, reducing surgically induced astigmatism, and facilitating intraoperative maneuvering. The location and type of incision depend upon multiple factors, such as age, ocular conditions, refractive status, and compliance. For pediatric patients, scleral tunnel, clear corneal tunnel, or limbal tunnel incisions can be made from a superior or temporal approach. This section will focus on the selection and construction of the incision in pediatric cataract surgeries.
12.2.1 Selection of Incision Type and Location
12.2.1.1 Incision Type
Based on the anatomical characteristics of a child’s eye, there are three types of incision commonly used in pediatric cataract surgery, and these are modified scleral tunnel, clear corneal, and limbal incisions. According to the incision architecture, cataract incisions can be classified into uniplanar, biplanar, and triplanar incisions. For young children, a modified biplanar scleral tunnel incision is recommended. This may promote self-sealing of the incision by taking advantage of the scleral tension, the posterior incision flap, and the intraocular pressure (IOP). Taken all together, this improves surgical safety and lowers the incidence of surgical injuries and the possibility of surgically induced astigmatism.
12.2.1.2 Incision Location
Location of the incision may be described according to its relative position to the cornea center or its anatomic position. The most common sites of incision are superior, temporal, and on the steep meridian. If the bimanual approach is chosen for irrigation/aspiration (I/A), two paracentesis incisions are made at the 10 o’clock and 2 o’clock positions.
Infants and young children with congenital cataracts have low scleral rigidity; incisions in this population are hardly self-sealing; their compliance to postoperative treatments and care is poor, and they frequently rub their eyes. Therefore, a superior, modified scleral tunnel incision is recommended in these children, so that the wound is protected by both the upper eyelid and conjunctiva, reducing the risk of wound leakage or dehiscence due to external factors such as trauma [10]. Children receiving cataract surgery under 1 year of age, with a horizontal corneal diameter of less than 10 mm or an extremely short axial length, or accompanied by persistent fetal vasculature (PFV) are at a higher risk of developing secondary glaucoma [11–13]. Creation of a conjunctival flap during cataract surgery may be associated with local adhesion to the bulbar conjunctiva and scar formation, increasing the risk of subsequent antiglaucoma surgery failure. In such cases, the surgical incision should be made at the nasal superior or temporal superior quadrant in order to preserve healthy bulbar conjunctiva for possible antiglaucoma surgery in the future. In addition, when complicated with corneal trauma, ectopia lentis, synechia, iris coloboma, iridodialysis, or intraocular foreign bodies, the location of the incision should aim to minimize further injuries to the eye (e.g., avoid making an incision at the site of lens dislocation) and ease intraoperative maneuvering.
For children over 10 years old, the eyes are relatively mature, and the incisions have a better self-sealing capability so the incision may be made at the temporal clear corneal or limbus. Since the temporal incision is located near the palpebral fissure area, it proves to be beneficial for intraoperative maneuvering, with better visibility, and avoids destruction of the bulbar conjunctiva that would be caused by a superior corneoscleral tunnel incision. For patients with vitreous or retinal disorders, or when the surgeon prefers to use a vitrector handpiece for lensectomy, the pars plana scleral incision may be another option.
12.2.2 Techniques and Features of Incisions
12.2.2.1 Modified Scleral Tunnel Incision
The modified scleral tunnel incision has a wide range of applications, particularly for children under 10 years. The principles of a modified scleral tunnel incision construction in pediatric cataract surgery are similar to the techniques in adults, with the following steps (Fig. 12.4a–e):
Fig. 12.4
Construction and suturing of a corneoscleral tunnel incision/limbal tunnel incision. (a) Superior rectus suspension; (b) conjunctival opening; (c) scleral cauterization; (d) starting position of the tunnel incision; (e) anterior chamber entry made at an angle of 45°; (f) suture closure parallel to the limbus; (g) knotting; (h) the knot is buried; (i) the conjunctival incision is closed using cauterization
- 1.
The superior rectus muscle is suspended, and the globe is rotated downward to expose the upper surgical field.
- 2.
Peritomy: a fornix-based conjunctival flap is made, and the bulbar conjunctiva is dissected along the limbus about 5 mm in width before cauterization. The superior portion of sclera is thereby exposed. The conjunctival incision may be enlarged, or a radial peritomy may be adopted to prevent conjunctival ballooning due to escaping irrigating solution into the subtenon space that interferes with surgical maneuvers.
- 3.
Creation of a scleral tunnel:
- 1.
At 1.5 mm posterior to the anterior margin of the limbus, a frown-shaped incision or a straight scleral incision is made with a diamond scalpel or a 15° disposable paracentesis scalpel to a depth of almost half the thickness of the sclera.
- 2.
With a crescent scalpel or a tunnel scalpel, the scleral tunnel is dissected, and the tunnel is extended into the clear cornea about 2–2.5 mm in length. For children under 3 years with soft eyes, the tunnel should not be too short. In the case of iris prolapse, it not only interferes with operative maneuvers but also leads to severer postoperative inflammatory response.
- 3.
Following the accomplishment of the corneoscleral tunnel, the anterior chamber entry is made at an angle of 45° with a “dimple-down” maneuver, to facilitate self-sealing of the incision. After entering the anterior chamber, the direction of the blade should be changed and moved to the iris plane to avoid injuring the iris or the capsule.
- 1.
A modified scleral tunnel incision has several advantages compared to a clear corneal incision [10]. With the same tunnel length, a corneoscleral incision minimizes the incidence of corneal distortion and corneal folds affecting the surgical field. As it is far from the visual axis, a modified scleral tunnel incision can reduce the risk of surgically induced astigmatism. Besides, the blood supply to the scleral tissues is abundant, resulting in rapid and tight incision healing. Pros and cons of a modified scleral tunnel incision and its indications are listed in Table 12.1.
Table 12.1
Corneoscleral tunnel incision
Pros | Convenient for enlargement if needed |
Minimal corneal distortion during surgery | |
Low risk of iris prolapse | |
Self-sealing with favorable stability | |
Cons | Complicated maneuvers, cauterization required |
Severe conjunctival edema may occur during surgery, affecting the surgical field | |
The disrupted superior conjunctiva may impact the functions of filtering blebs if subsequent filtration surgery is needed to treat secondary glaucoma | |
Indications | Infants and young children |
A rigid intraocular lens (IOL) has to be used, or when the type of IOL for implantation is not decided (foldable or rigid) |
12.2.2.2 Limbal Tunnel Incision
The construction technique of a limbal tunnel incision is similar to that of a corneoscleral tunnel incision, except that the incision starts from the limbal vessels’ ends. This type of incision not only retains some of the advantages of a corneoscleral tunnel incision, such as a lower rate of surgically induced astigmatism and a reduced risk of endophthalmitis, but also simplifies the construction procedure, by protecting the integrity of the conjunctiva, shortening the length of the incision, and enabling easier intraocular maneuvering.
12.2.2.3 Clear Corneal Tunnel Incision
The construction of a clear corneal incision in pediatric cataract surgery is similar to that of an adult eye. A uniplanar, biplanar, or triplanar clear corneal tunnel incision can be made with a paracentesis scalpel. At the end of the surgery, suture closure is not required since the incision is watertight. Besides, conjunctiva-related complications are avoided because the incision starts before the conjunctiva, which remains unaffected.
For babies under 1 year, suturing is often required due to their soft eyes and poor compliance, and such incisions are not self-sealing. Thus, this type of incision is more appropriate for children above 10 years old whose eyes are much more mature. Pros and cons of a clear corneal incision are listed in Table 12.2.
Pros | Simpler procedures without cauterization |
Untouched conjunctiva for better outcome in future filtration surgery | |
Ease of intraoperative maneuvering with shorter incision | |
Cons | Poor self-sealing ability, prone to dehiscence if left unsutured |
Due to an avascular structure, healing possibly delayed | |
Higher risk of endophthalmitis if left unsutured | |
Higher incidence of surgically induced astigmatism | |
Indications | Children over 10 years of age with a planned foldable lens implantation |
12.2.2.4 Limbal/Clear Corneal Microincision
Bimanual microincision cataract surgery is applicable to pediatric patients. Due to their soft lens nucleus, irrigation/aspiration can be used to remove the opacified lens, and therefore, the same clear corneal incision can be made, as in the bimanual microincision cataract extraction for adults, with a 1.0–1.5 mm paracentesis scalpel [19, 20].
For patients without primary intraocular lens (IOL) implantation, a vitrector tip may be used to aspirate the capsule and cortex plaque. A 20-gauge paracentesis scalpel is ideal to make the incision, starting just at or anterior to the margin of the limbal vascular arcade. The blade enters vertically to the corneal plane and then runs parallel to the iris plane into the anterior chamber. This type of incision is generally small and may ease operative maneuvering; the application of a vitrector handpiece for both anterior and posterior capsulotomy and cortex aspiration avoids frequent entering and exiting from the anterior chamber with surgical instruments and consequently decreases postoperative inflammatory responses. But on the downside, if the incision is too wide to maintain the anterior chamber, leakage occurs and the chamber may even disappear, which results in an increased risk of injuries to the iris and corneal endothelium.
12.2.2.5 Pars Plana Incision
A pars plana incision is indicated for pediatric cataract patients with concurrent vitreous and retinal disorders. As the pars plana is still immature in children and the peripheral retina is closer to the cornea compared with adult eyes, the location for incision is quite different [12]. After peritomies at the 2 o’clock and 10 o’clock positions and infra-temporally, the pars plana entry is created approximately 1.5–3.5 mm posterior to the limbus with a 20-gauge scleral paracentesis scalpel (Table 12.3).
Frequent entries and exits of surgical instruments into the anterior chamber should be avoided. During irrigation, instruments are not allowed to slip out of the tunnel, in case of vitreous incarceration into the incision and further hyperplasia of the anterior vitreous. This kind of incision not only minimizes injuries to the anterior chamber but, in the meantime, enables the management of vitreous and retinal conditions. But the residual capsule may be insufficient to support secondary sulcus IOL implantation. In addition, the learning curve may be long for an ophthalmologist who is focused on the anterior segment to get used to this type of incision.
12.2.3 Suturing
In pediatric cataract surgery, a watertight closure of the incision should always be ensured, no matter what kind of incision is chosen. For younger children, especially those combined with posterior capsulotomy or vitrectomy, suturing the incision should always be stressed, so as to prevent spontaneous or trauma-induced wound dehiscence or leakage, or other catastrophic complications such as anterior chamber disappearance, pupillary occlusion, IOP elevation, or endophthalmitis [23–25].
Methods may vary in suturing a corneal or corneoscleral incision, e.g., radial suturing vertical to the limbus or mattress suturing parallel to the incision (Fig. 12.4f–h). Regardless of which method is chosen, the internal lip of the wound should always be fixed and sutured. Meanwhile, the suture tension should be adjusted to maintain corneal curvature. The conjunctival incision can be closed by either suturing or cauterization (Fig. 12.4i).
In summary, a careful and comprehensive preoperative assessment should be performed, so as to select an appropriate and safe incision based on the patient’s age together with ocular conditions and plan the best surgical approach. For infants or those accompanied with glaucoma or at a high risk of developing into secondary glaucoma, the bulbar conjunctiva should be preserved as much as possible so as to support any future antiglaucoma surgery. To prevent incision leakage during surgery, the size of the incision should be compatible with the surgical instruments. Moreover, it is important to close the incision by suturing in order to avoid potential complications.
12.3 Use of Ophthalmic Viscosurgical Devices
Since their introduction in the 1970s, ophthalmic viscosurgical devices (OVDs), also called viscoelastic materials or viscoelastics, have become an integral part of ophthalmic surgeries [26–28]. Specific features of the pediatric eye, for instance, a shallower anterior chamber, a pupil that is more resistant to dilation, and a higher vitreous pressure, make it important to maintain an adequate intraoperative maneuvering space. Besides, a soft eye wall and elastic lens capsule add to the difficulties in anterior or posterior capsulotomy. Thus, better understanding of the characteristics of different OVDs and rational selection of appropriate OVDs would enable the surgery to be easier and safer.
12.3.1 OVD Rheology and Physical Properties
- 1.
Viscosity: Viscosity is defined as the measurement of internal friction caused by the solution’s resistance to flow such as shear stress or tensile stress. Viscosity mainly depends on the length of the molecular chain, as well as molecular weight, concentration, solvent, and temperature [29].
The viscosity of OVDs varies with shear rate. Shear rate is defined as the relative movement speed of two adjacent layers in a moving liquid. High viscosity at zero shear rate maintains the space for surgical maneuvering; moderate viscosity at medium shear rates facilitates movement of surgical instruments or IOLs within the eye; and low viscosity at high shear rates enables easy OVD injection through a needle cannula [30].
- 2.
Pseudoplasticity: Pseudoplasticity is defined as the OVD’s ability to transform when under pressure from a gel-like state to a more liquid state [31]. All OVDs are pseudoplastic, demonstrating decreased viscosity as the shear force (external stress) is increased. Pseudoplasticity correlates with the OVD’s ability to maintain surgical space and the level of difficulty of OVD injection [30]. When an OVD is injected or a surgical instrument moves across the OVD, the increased shear rate decreases the viscosity of the OVD, allowing a more liquid state and so facilitating intraoperative maneuvers.
- 3.
Elasticity: Elasticity refers to the tendency of a material to return to its initial size and shape after it has been deformed, which often increases with viscosity. The elasticity of OVDs can reduce the ultrasonic vibration during phacoemulsification and irrigation/aspiration and minimize the intraocular injuries caused by fluctuation [29].
- 4.
Cohesiveness: Cohesiveness describes the degree of self-adhesion; it is a function of molecular weight and elasticity [29]. Long-stranded OVDs with a high molecular weight (HMW) tend to be more cohesive and thus allow for easy removal, whereas short-stranded OVDs with a low molecular weight are less cohesive and behave in a dispersive fashion and are thus more difficult to remove completely.
- 5.
Dispersiveness: Contrary to cohesiveness, dispersiveness is the inclination of a material to disperse when it is injected into the anterior chamber. Typically dispersive agents have lower molecular weights and shorter molecular chains [29].
- 6.
Coatability: Coatability describes the ability of a certain material to adhere to the surface of tissues, instruments, and implants. A lower contact angle and a lower surface tension indicate better coatability. In addition, negatively charged OVDs better coat the positively charged surface of instruments [30].
According to their viscosity, cohesiveness, and dispersiveness at rest, OVDs are classified into higher-viscosity cohesive agents and lower-viscosity dispersive agents [32, 33]. The cohesiveness and dispersiveness of an OVD may alter under different shear rates. For example, Healon5 has a high viscosity at a quiescent state and becomes dispersive by fracturing into particles under medium shear rate. This property of Healon5 is called viscoadaptivity [26, 31]. The advent of DisCoVisc, which possesses a high viscosity at rest and becomes a dispersive agent during phacoemulsification, promotes a modified classification of OVDs based on their molecular weight and cohesion-dispersion index (CDI) [31]. The new classification system as proposed in 2005 and some of the commercially available OVDs are listed in Table 12.4.
Table 12.4
New classification of OVDs and commercially available OVDs
Zero shear viscosity range (mPa · s) | Cohesive OVDs (components) CDI ≥ 30 (% asp/mmHg) | Dispersive OVDs (components) CDI ≤ 30 (% asp/mmHg) |
|---|---|---|
7–18 × 106 | I. Superviscous adaptativesa Healon5 (2.3 % HA) iVisc Phaco (2.3 % HA) | I. Ultraviscous dispersives None |
1–5 × 106 | II. Higher-viscosity cohesives A. Superviscous cohesives Healon GV (1.4 % HA) iVisc Phaco plus (1.4 % HA) | II. Higher-viscosity dispersives A. Superviscous dispersives None |
105–106 | B. Viscous cohesives Amvisc Plus (1.6 % HA) Amvisc (1.2 % HA) Biolon (1.0 % HA) Healon (1.0 % HA) Provisc (1.0 % HA) Viscorneal Plus (1.4 % HA) | B. Viscous dispersives DisCoVisc (4.0 % HA + 1.7 % CDS) |
104–105 | III. Lower-viscosity cohesives A. Medium-viscosity cohesives None | III. Lower-viscosity dispersives A. Medium-viscosity dispersives Viscoat (3.0 % HA + 4 % CDS) Biovisc (3.0 % HA + 4 % CDS) ViTrax (3.0 % HA) Cellugel (3.0 % HPMC) |
103–104 | B. Very low-viscosity cohesives None | B. Very low-viscosity dispersives Adatocel (2.0 % HPMC) Hymecel (2.0 % HPMC) iCell (2.0 % HPMC) OcuCoat (2.0 % HPMC) Visilon (2.0 % HPMC) |
12.3.2 Types and Features of OVDs
The currently used OVDs are mainly based on sodium hyaluronate, hydroxypropyl methylcellulose (HPMC), or chondroitin sulfate (CDS).
12.3.2.1 Hyaluronic Acid (HA) Sodium
HA is a natural lubricant found in the extracellular matrices of almost all vertebrates. In ocular tissues, high levels of HA are found in the vitreous and trabecular angle, while low levels of HA are present in the aqueous humor and over the corneal endothelium, protecting the corneal endothelial cells during surgery [29, 34, 35]. As HA is very viscous and elastic [29], it can effectively maintain the depth of the intraoperative anterior chamber and stress the lens and vitreous to the back, facilitating capsulorhexis and preventing vitreous prolapse. Moreover, HA can eliminate free radicals formed during surgery, thus protecting intraocular tissues from being damaged [36]. Also, its high pseudoplasticity allows for easy injection through a needle cannula. However, since HA cannot be metabolized in the eye and is mainly eliminated through trabecular meshwork filtration, its retention may lead to transient IOP elevation. Additionally, all OVDs containing HA require low temperature preservation and acclimation to the operating room temperature before use, which may limit its widespread use in less developed areas.
The commercially available HA products include Healon, Healon5, Healon GV, Provisc, Amvisc, Amvisc Plus, Biolon, iViz, Singclean, Yishukang, and Qisheng.
12.3.2.2 Hydroxypropyl Methylcellulose (HPMC)
HPMC does not occur naturally in the eye and is synthesized from methylcellulose. Because of its lower surface tension and smaller contacting angle, HPMC has a better ability to coat the surface of intraocular tissues and surgical instruments, helping to protect the corneal endothelial cells. Due to its small molecular weight, 97 % of HPMC can be eliminated via the trabecular meshwork about 24 h after its injection into the anterior chamber. But the poor elasticity and pseudoplasticity of HPMC means that it requires a large-bore cannula for injection. Moreover, HPMC injection into the anterior chamber is likely to bring air bubbles affecting transparency, thus reducing the visibility of intraocular structures. Since the viscosity is quite low, HPMC tends to leak out of the incision when the anterior chamber pressure is elevated. But HPMC has the advantages of lower cost and being able to be stored at room temperature [29].
OcuCoat, Hymecel, Cellugel, and Adatocel are some of the commonly used HPMC OVDs.
12.3.2.3 Chondroitin Sulfate (CDS)
CDS is found in the cornea and vitreous [37, 38], and because it is negatively charged, it has the ability to coat the positively charged intraocular tissues and instruments. Its viscosity is poor at low concentrations but can be increased when the CDS concentration exceeds 50 %. Intraocular injection at such a high concentration, however, may result in corneal endothelial dehydration and damage. Since the viscosity of CDS depends largely upon its concentration, all available CDS OVDs at present are a combined regimen. The combination of CDS and HA gives rise to a distinctive chemical configuration with favorable coating ability and viscosity, which is considered as an ideal OVD. The commercially available combination products include Viscoat (4 % CDS + 3 % HA), DisCoVisc (4 % HA + 1.7 % CDS), and Ocugel (0.5 % CDS + 2.75 % HPMC).
12.3.3 Use of OVDs in Pediatric Lens Surgery
Considering the soft eyes and limited space for maneuvering, together with the high vitreous pressure encountered during pediatric surgery, selecting an appropriate OVD is particularly important. OVDs have the following applications during pediatric cataract surgery:
- 1.
Protection of corneal endothelium: Since human corneal endothelium cannot regenerate, the use of an OVD is required in both adult and pediatric cataract surgeries, to protect the endothelial cells via physical contact and chemical reactions and minimize the thermal injuries during phacoemulsification, as well as mechanical injuries caused by irrigation and surgical instruments [39]. OVDs play an essential role in protecting corneal endothelial cells from intraoperative loss [40–43]. They are particularly essential in children who are in need of at least two intraocular surgeries. Thus, the use of OVDs with good elasticity and coating ability is recommended for protection of the corneal endothelial cells.
- 2.
Maintenance of anterior chamber depth: The depth of the anterior chamber is at its minimum in the newborn eye, reaching its final adult depth at between 8 and 12 years. However, the depth will decrease in the presence of advanced intumescent infantile or childhood cataracts. Besides, as the sclera is relatively thin in pediatric eyes, repeated entries and exits of instruments into and out of the incision may lead to anterior chamber instability. For capsulorhexis or other intraocular procedures, it is necessary to inject an adequate amount of high-viscosity cohesive OVD into the anterior chamber, which can deepen it and create more space for safer surgical maneuvering.
- 3.
Assisting anterior capsulorhexis: The pediatric anterior lens capsule is thinner and more elastic than that in adults, which also adds to the difficulty encountered during continuous curvilinear capsulorhexis (CCC). Moreover, vitreous upthrust from lower scleral rigidity promotes OVDs to leak out of the incision, resulting in an anterior-posterior pressure imbalance and hence anterior capsule radial tearing during surgery. It is recommended that prior to capsulorhexis, a high-viscosity OVD be injected to fill the anterior chamber (Fig. 12.5), thus flattening the anterior lens capsule surface, diminishing the risk of anterior capsule radial tearing and reducing the chances of potential complications [44, 45].
Fig. 12.5
OVD injection into the anterior chamber. Injecting an OVD into the anterior chamber to flatten the anterior lens capsule and aid anterior continuous curvilinear capsulorhexis
- 4.
Assisting posterior capsulorhexis: Due to the increased risk of/for secondary cataract in children and the anatomic characteristics of the posterior capsule in patients with posterior polar cataract, posterior continuous curvilinear capsulorhexis (PCCC) may be required. In this case, injecting a moderate amount of highly cohesive OVD into the capsular bag can stretch and stabilize the posterior capsule and also neutralize the posterior vitreous pressure, easing posterior capsulorhexis.
- 5.
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Assisting IOL implantation: Use of OVD to fill the anterior chamber and maintain the capsular bag enables slow unfolding of a foldable IOL and increases the adjustability of the IOL in the capsule bag.
As for secondary IOL implantation, if posterior capsulorhexis and anterior vitrectomy have already been performed, using OVD to neutralize the vitreous pressure can prevent vitreous prolapse when an IOL is being implanted. If the peripheral capsular bag remains intact, an OVD should be injected after the proliferated cortex has been removed, so as to reopen the peripheral capsular bag for “in-the-bag” IOL implantation (Fig. 12.6). In addition, the OVD can adhere to the surface of the IOL, reducing its surface charge and preventing injury to corneal endothelial cells caused by direct contact with the IOL [42].
Fig. 12.6
OVD injection into the anterior chamber and capsular bag. OVD injection to maintain the anterior chamber depth and expand the capsular bag, easing IOL implantation
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