Introduction
The indications for lens surgery today may be classified into two main categories:
- •
Medical – surgical or pathological indication, and
- •
Optical – or refractive lens exchange.
Medical indications arise from pathological states of the lens of varying causes, usually related to lens clarity, lens position, or other lens-related conditions, such as inflammation, glaucoma, or the threat of glaucoma. Surgical or pathological indications have existed for centuries, if not millennia, and are generally indisputable. Refractive indications for lens surgery, in contrast, include clear lens ametropic refractive states. The current high standards of lens surgery in terms of safety, accuracy, and customization have opened a new world of refractive correction for many patients who were previously considered untreatable. Lens surgery has found an indisputable position in refractive surgery among the various competitors of laser surgery, phakic IOL (intraocular lens) surgery, and incisional corneal surgery. As customization has improved for each age group and each refractive error group, so have the various treatment modalities expanded or contracted with respect to patient safety and accuracy of outcome.
Medical Indications for Lens Surgery
Lenticular Opacification (Cataract)
The medical indications for lens surgery ( Box 5.6.1 ) are true pathological states, some of which may threaten the integrity of the whole organ (the eye). They also interfere with a major ocular function: focused vision. Lenticular malformation and opacification obstruct the pathway of light; reduce the available quantity of light; scatter light off axis; reduce contrast sensitivity; diminish color intensity; reduce resolution acuity; may alter lens texture in such a way as to contribute to a decrease in accommodation amplitude, particularly in the case of presenile nuclear sclerosis; and, in the case of progressive nuclear sclerosis, often result in a myopic alteration of a previously stable lifelong refractive state.
- I.
Lenticular opacification (cataract)
- II.
Lenticular malposition
- A.
Subluxation
- B.
Dislocation
- A.
- III.
Lenticular malformation
- A.
Coloboma
- B.
Lenticonus
- C.
Lentiglobus
- D.
Spherophakia
- A.
- IV.
Lens-induced inflammation
- A.
Phacotoxic uveitis (phacoanaphylaxis)
- B.
Phacolytic glaucoma
- C.
Phacomorphic glaucoma
- A.
- V.
Lenticular tumor
- A.
Epithelioma
- B.
Epitheliocarcinoma
- A.
- VI.
Facilitatory (surgical access)
- A.
Vitreous base
- B.
Ciliary body
- C.
Ora serrata
- A.
It is generally agreed that surgical intervention is indicated when there is “functional” visual impairment.
The boundary between refractive surgery and cataract surgery remains somewhat blurred, especially in view of the variable nature of what patients deem loss of “functional” vision. A boundary, however, is necessary for the separation in terms of insured payments. The degree to which the opacification obstructs light can, additionally, be measured by laser interferometry. Progressive changes in cataract density over time can be documented by slit-lamp estimation using the Lens Opacification Classification System (LOCS-III) devised by Chylack and coworkers, by Scheimpflug photography of nuclear cataracts and by Neitz-Kawara retroillumination photography of posterior sub-capsular cataracts. A useful figure to use for cataract/noncataract separation is approximately 20% opacification on Pentacam Scheimpflug densitometry ( Fig. 5.6.1 ).
Cataract in the Presence of Other Ocular Disorders
The decision regarding whether and when to remove a cataract in an otherwise healthy eye usually depends on the impact of the cataract on the visual function of the eye and the impact of that level of visual impairment on the person’s life. The status of the other eye also is important. In healthy eyes whose only disorder is cataract, the presumed outcome after uncomplicated surgery is better vision than before surgery. Indeed, in high-volume cataract units, a success rate of 98% can be expected. Thus when one applies a risk–benefit ratio with such a high degree of success, surgery is usually the mutually agreed upon course.
However, such may not be the case when the cataract is associated with other disorders, especially if they are contributing factors to the loss of vision of an eye. Therefore, such conditions as amblyopia, corneal opacification, vitreous opacification, maculopathy, retinopathy, glaucoma, and optic neuropathy may alter or delay the decision to operate, based not so much on the expected risks but rather on the limited benefits. In some cases, lens surgery is indicated to preserve peripheral vision only for functional ambulation. In other cases, maintenance of a posterior segment view for treatment purposes in progressive posterior segment conditions is an indication for lens surgery, even when the expectation for visual improvement may be minimal. Also, if the other eye is blind, the surgery may be delayed.
Systemic conditions may play a role in deciding whether and when to remove a cataract. Is the patient’s diabetes under control? Has there been a stroke with hemianopia? Is the patient on systemic anticoagulants? Is the patient terminally ill or immunologically suppressed? Does the patient have Alzheimer’s disease or severe co-operation difficulty?
Thus, the decision to remove a cataract may become a collaborative endeavor, with participation by the patient, the patient’s family, the patient’s primary physician, the surgeon, a governmental agency, and a third-party payer. The decision, therefore, is determined not only by technological findings and expectations, but also by a “holistic” evaluation of the impact of such a decision on that person’s life, as defined by that society. Various tests are available to assess degrees of disability, such as the Visual Function Index (VF-14) or the Activities of Daily Vision Scale (ADVS).
Lenticular Malposition
Subluxation (the displacement of the lens within the posterior chamber) and dislocation (displacement of the lens out of the posterior chamber into the anterior chamber or vitreous) of the lens are different degrees of the same phenomenon and result from dysfunction of the zonules. The zonules may be defective as a result of congenital malformation, total or partial agenesis, or a hereditary metabolic disorder, such as Marfan’s syndrome. Chronic inflammation and pseudoexfoliation have been shown to be associated with a weakness in the zonular fibers or their attachments. Ocular trauma is an obvious cause. Subluxation, in the absence of associated sequelae, may not be visually significant and may not be an indication for lensectomy. Similarly, complete dislocation of an intact lens into the inferior vitreous may be a quiescent event in the absence of inflammation and may simply produce a state of refractive aphakia, correctable nonsurgically with a spectacle or contact lens or surgically with IOL implantation. Subluxation to the extent that the equator of the lens is visible in the midsized pupil is usually visually significant, causing glare, fluctuating vision, and monocular diplopia. This symptom complex would qualify for lens surgery.
Lenticular Malformation
These conditions of abnormal lens development are congenital. They may be genetic, hereditary, or the result of intrauterine infection or trauma. These conditions include lens coloboma, lenticonus, lentiglobus, and spherophakia, as well as varieties of congenital cataract, such as rubella and Lowe’s syndrome. Partial iris coloboma or total aniridia, whether congenital, traumatic, or surgical, may be an indication for lens surgery to improve visual function or for cosmesis. The availability of aniridia IOLs ( Fig. 5.6.2A ) and opaque endocapsular rings (see Fig. 5.6.2B,C ) offers great improvements for such patients.
The indications for surgery depend on the degree to which the specific malformation interferes with vision or the integrity of the involved eye. Such abnormalities may be associated with amblyopia. Early detection and surgical intervention should be incorporated with a plan for amblyopia therapy.
Lens-Induced Ocular Inflammation
Phacoanaphylactic endophthalmitis (phacotoxic uveitis) occurs in an immunologically mature and competent host and is related to physical or chemical disruption of the lens capsule. Surgery may be the appropriate treatment for this form of ocular inflammation.
Lens-Induced Glaucoma
Inflammatory Glaucoma (Phacolytic Glaucoma)
Phacolytic glaucoma occurs in an eye with a mature lens in which the lens capsule is intact. Denatured, nonantigenic liquefied lens material leaks out through the intact lens capsule and elicits a macrophagic, inflammatory reaction. The macrophages, engorged with lens material, clog the open angle, leading to a secondary open-angle glaucoma. Removal of the lens and intraocular lens placement is usually curative, obviating the need for other forms of medical or surgical pressure management.
Pupil Block and Angle Closure (Phacomorphic Glaucoma)
Similarly, removal of the lens in this instance is also curative. The growth of the lens with age progressively engulfs anterior segment space and may ultimately lead to acute angle–closure glaucoma through the mechanism of pupillary block. This is more likely in hyperopic eyes due to the short axial length and already crowded anterior segments. Lens removal and replacement with an intraocular lens greatly increases anterior segment space and in most instances resolves the glaucoma.
Lenticular Opacification (Cataract)
The medical indications for lens surgery ( Box 5.6.1 ) are true pathological states, some of which may threaten the integrity of the whole organ (the eye). They also interfere with a major ocular function: focused vision. Lenticular malformation and opacification obstruct the pathway of light; reduce the available quantity of light; scatter light off axis; reduce contrast sensitivity; diminish color intensity; reduce resolution acuity; may alter lens texture in such a way as to contribute to a decrease in accommodation amplitude, particularly in the case of presenile nuclear sclerosis; and, in the case of progressive nuclear sclerosis, often result in a myopic alteration of a previously stable lifelong refractive state.
- I.
Lenticular opacification (cataract)
- II.
Lenticular malposition
- A.
Subluxation
- B.
Dislocation
- A.
- III.
Lenticular malformation
- A.
Coloboma
- B.
Lenticonus
- C.
Lentiglobus
- D.
Spherophakia
- A.
- IV.
Lens-induced inflammation
- A.
Phacotoxic uveitis (phacoanaphylaxis)
- B.
Phacolytic glaucoma
- C.
Phacomorphic glaucoma
- A.
- V.
Lenticular tumor
- A.
Epithelioma
- B.
Epitheliocarcinoma
- A.
- VI.
Facilitatory (surgical access)
- A.
Vitreous base
- B.
Ciliary body
- C.
Ora serrata
- A.
It is generally agreed that surgical intervention is indicated when there is “functional” visual impairment.
The boundary between refractive surgery and cataract surgery remains somewhat blurred, especially in view of the variable nature of what patients deem loss of “functional” vision. A boundary, however, is necessary for the separation in terms of insured payments. The degree to which the opacification obstructs light can, additionally, be measured by laser interferometry. Progressive changes in cataract density over time can be documented by slit-lamp estimation using the Lens Opacification Classification System (LOCS-III) devised by Chylack and coworkers, by Scheimpflug photography of nuclear cataracts and by Neitz-Kawara retroillumination photography of posterior sub-capsular cataracts. A useful figure to use for cataract/noncataract separation is approximately 20% opacification on Pentacam Scheimpflug densitometry ( Fig. 5.6.1 ).
Cataract in the Presence of Other Ocular Disorders
The decision regarding whether and when to remove a cataract in an otherwise healthy eye usually depends on the impact of the cataract on the visual function of the eye and the impact of that level of visual impairment on the person’s life. The status of the other eye also is important. In healthy eyes whose only disorder is cataract, the presumed outcome after uncomplicated surgery is better vision than before surgery. Indeed, in high-volume cataract units, a success rate of 98% can be expected. Thus when one applies a risk–benefit ratio with such a high degree of success, surgery is usually the mutually agreed upon course.
However, such may not be the case when the cataract is associated with other disorders, especially if they are contributing factors to the loss of vision of an eye. Therefore, such conditions as amblyopia, corneal opacification, vitreous opacification, maculopathy, retinopathy, glaucoma, and optic neuropathy may alter or delay the decision to operate, based not so much on the expected risks but rather on the limited benefits. In some cases, lens surgery is indicated to preserve peripheral vision only for functional ambulation. In other cases, maintenance of a posterior segment view for treatment purposes in progressive posterior segment conditions is an indication for lens surgery, even when the expectation for visual improvement may be minimal. Also, if the other eye is blind, the surgery may be delayed.
Systemic conditions may play a role in deciding whether and when to remove a cataract. Is the patient’s diabetes under control? Has there been a stroke with hemianopia? Is the patient on systemic anticoagulants? Is the patient terminally ill or immunologically suppressed? Does the patient have Alzheimer’s disease or severe co-operation difficulty?
Thus, the decision to remove a cataract may become a collaborative endeavor, with participation by the patient, the patient’s family, the patient’s primary physician, the surgeon, a governmental agency, and a third-party payer. The decision, therefore, is determined not only by technological findings and expectations, but also by a “holistic” evaluation of the impact of such a decision on that person’s life, as defined by that society. Various tests are available to assess degrees of disability, such as the Visual Function Index (VF-14) or the Activities of Daily Vision Scale (ADVS).
Cataract in the Presence of Other Ocular Disorders
The decision regarding whether and when to remove a cataract in an otherwise healthy eye usually depends on the impact of the cataract on the visual function of the eye and the impact of that level of visual impairment on the person’s life. The status of the other eye also is important. In healthy eyes whose only disorder is cataract, the presumed outcome after uncomplicated surgery is better vision than before surgery. Indeed, in high-volume cataract units, a success rate of 98% can be expected. Thus when one applies a risk–benefit ratio with such a high degree of success, surgery is usually the mutually agreed upon course.
However, such may not be the case when the cataract is associated with other disorders, especially if they are contributing factors to the loss of vision of an eye. Therefore, such conditions as amblyopia, corneal opacification, vitreous opacification, maculopathy, retinopathy, glaucoma, and optic neuropathy may alter or delay the decision to operate, based not so much on the expected risks but rather on the limited benefits. In some cases, lens surgery is indicated to preserve peripheral vision only for functional ambulation. In other cases, maintenance of a posterior segment view for treatment purposes in progressive posterior segment conditions is an indication for lens surgery, even when the expectation for visual improvement may be minimal. Also, if the other eye is blind, the surgery may be delayed.
Systemic conditions may play a role in deciding whether and when to remove a cataract. Is the patient’s diabetes under control? Has there been a stroke with hemianopia? Is the patient on systemic anticoagulants? Is the patient terminally ill or immunologically suppressed? Does the patient have Alzheimer’s disease or severe co-operation difficulty?
Thus, the decision to remove a cataract may become a collaborative endeavor, with participation by the patient, the patient’s family, the patient’s primary physician, the surgeon, a governmental agency, and a third-party payer. The decision, therefore, is determined not only by technological findings and expectations, but also by a “holistic” evaluation of the impact of such a decision on that person’s life, as defined by that society. Various tests are available to assess degrees of disability, such as the Visual Function Index (VF-14) or the Activities of Daily Vision Scale (ADVS).
Lenticular Malposition
Subluxation (the displacement of the lens within the posterior chamber) and dislocation (displacement of the lens out of the posterior chamber into the anterior chamber or vitreous) of the lens are different degrees of the same phenomenon and result from dysfunction of the zonules. The zonules may be defective as a result of congenital malformation, total or partial agenesis, or a hereditary metabolic disorder, such as Marfan’s syndrome. Chronic inflammation and pseudoexfoliation have been shown to be associated with a weakness in the zonular fibers or their attachments. Ocular trauma is an obvious cause. Subluxation, in the absence of associated sequelae, may not be visually significant and may not be an indication for lensectomy. Similarly, complete dislocation of an intact lens into the inferior vitreous may be a quiescent event in the absence of inflammation and may simply produce a state of refractive aphakia, correctable nonsurgically with a spectacle or contact lens or surgically with IOL implantation. Subluxation to the extent that the equator of the lens is visible in the midsized pupil is usually visually significant, causing glare, fluctuating vision, and monocular diplopia. This symptom complex would qualify for lens surgery.
Lenticular Malformation
These conditions of abnormal lens development are congenital. They may be genetic, hereditary, or the result of intrauterine infection or trauma. These conditions include lens coloboma, lenticonus, lentiglobus, and spherophakia, as well as varieties of congenital cataract, such as rubella and Lowe’s syndrome. Partial iris coloboma or total aniridia, whether congenital, traumatic, or surgical, may be an indication for lens surgery to improve visual function or for cosmesis. The availability of aniridia IOLs ( Fig. 5.6.2A ) and opaque endocapsular rings (see Fig. 5.6.2B,C ) offers great improvements for such patients.
The indications for surgery depend on the degree to which the specific malformation interferes with vision or the integrity of the involved eye. Such abnormalities may be associated with amblyopia. Early detection and surgical intervention should be incorporated with a plan for amblyopia therapy.
Lens-Induced Glaucoma
Inflammatory Glaucoma (Phacolytic Glaucoma)
Phacolytic glaucoma occurs in an eye with a mature lens in which the lens capsule is intact. Denatured, nonantigenic liquefied lens material leaks out through the intact lens capsule and elicits a macrophagic, inflammatory reaction. The macrophages, engorged with lens material, clog the open angle, leading to a secondary open-angle glaucoma. Removal of the lens and intraocular lens placement is usually curative, obviating the need for other forms of medical or surgical pressure management.
Pupil Block and Angle Closure (Phacomorphic Glaucoma)
Similarly, removal of the lens in this instance is also curative. The growth of the lens with age progressively engulfs anterior segment space and may ultimately lead to acute angle–closure glaucoma through the mechanism of pupillary block. This is more likely in hyperopic eyes due to the short axial length and already crowded anterior segments. Lens removal and replacement with an intraocular lens greatly increases anterior segment space and in most instances resolves the glaucoma.
Inflammatory Glaucoma (Phacolytic Glaucoma)
Phacolytic glaucoma occurs in an eye with a mature lens in which the lens capsule is intact. Denatured, nonantigenic liquefied lens material leaks out through the intact lens capsule and elicits a macrophagic, inflammatory reaction. The macrophages, engorged with lens material, clog the open angle, leading to a secondary open-angle glaucoma. Removal of the lens and intraocular lens placement is usually curative, obviating the need for other forms of medical or surgical pressure management.
Pupil Block and Angle Closure (Phacomorphic Glaucoma)
Similarly, removal of the lens in this instance is also curative. The growth of the lens with age progressively engulfs anterior segment space and may ultimately lead to acute angle–closure glaucoma through the mechanism of pupillary block. This is more likely in hyperopic eyes due to the short axial length and already crowded anterior segments. Lens removal and replacement with an intraocular lens greatly increases anterior segment space and in most instances resolves the glaucoma.
Refractive Indications for Lens Surgery
Refinements in measurement technology, ocular anesthesia, incision technology, lensectomy techniques, ophthalmic viscosurgical devices (OVD) tissue protection, and IOL technology has allowed the accurate and successful correction of refractive errors.
Almost all the operable tissues and spaces of the eye have, over decades, come under investigation as locations for refractive surgical modulation: corneal epithelial surface, corneal stroma, corneal endothelial surface, anterior chamber, iris, pupil, posterior chamber, lens, and sclera. The lens, therefore, assumes its role among the others as a popular location for surgical refractive modulation, sparing the other tissues where appropriate or necessary.
Clear lens replacement stands as a viable procedure today for both myopia and hyperopia, with the abilities now to control astigmatism ( Fig. 5.6.3A ), modulate higher-order aberration (see Fig. 5.6.3C ), and reduce presbyopic symptoms (see Fig. 5.6.3B,E ). Patient demand for these services has increased dramatically in recent times.
Multifocal IOLs (see Fig. 5.6.3B ) represent some of the first attempts at the intraocular correction of presbyopia. Other attempts at the development of a truly accommodative pseudophakos have included the intracapsular injection of liquid silicone and the intracapsular placement of high-water-content poly-HEMA lenses, a liquid silicone-filled intracapsular balloon, multiple IOLs (polypseudophakia) (see Fig. 5.6.3D ), and the flexing haptic accommodative IOLs (see Fig. 5.6.3E ).
Indications for Different Lens Surgery Techniques
Surgery affecting the human lens can be organized historically by its chronology of development ( Table 5.6.1 ) or divided into four major categories by technique ( Box 5.6.2 ). The indications for a particular lens surgery technique may be determined by several factors ( Box 5.6.3 ). Different medical conditions or pathological states of the eye and the lens may favor one technique over another. In some countries, the availability of equipment and the level of training of the surgeon may be factors that dictate technique. Certain countries have governmental agencies, professional organizations, academic institutions, insurance payers, or surgical facilities that regulate and control the types of surgical techniques surgeons may perform. For the purpose of this text, however, only specific medical or pathological conditions of the eye are discussed as factors determining the choice of surgical technique.
| Year | Technique | Place | Surgeon |
|---|---|---|---|
| 800 | Couching | India | Unknown |
| 1015 | Needle aspiration | Iraq | Unknown |
| 1100 | Needle aspiration | Syria | Unknown |
| 1500 | Couching | Europe | Unknown |
| 1745 | ECCE inferior incision | France | Daviel |
| 1753 | ICCE by thumb expression | England | Sharp |
| 1860 | ECCE superior incision | Germany | von Graefe |
| 1880 | ICCE by muscle-hook zonulysis and lens tumble | India | Smith |
| 1900 | ICCE by capsule forceps | Germany | Verhoeff Kalt |
| 1940 | ICCE capsule suction erysiphake | Europe | Stoewer I. Barraquer |
| 1949 | ECCE posterior chamber IOL and operating microscope | England | Ridley |
| 1951 | Anterior chamber IOLs | Italy Germany | Strampelli Dannheim |
| 1957 | ICCE by enzyme zonulysis | Spain | J. Barraquer |
| 1961 | ICCE by capsule cryoadhesion | Poland | Krawicz |
| 1967 | ECCE by phacoemulsification | United States | Kelman J. Shock |
| 1975 | Iris-pupil supported IOLs | Netherlands | Binkhorst Worst |
| 1984 | Foldable IOLs | United States South Africa | Mazzocco Epstein |
- I.
Lens repositioning (“couching”)
- A.
Extracapsular
- B.
Intracapsular
- 1.
Physical (instrumental) zonulysis
- 2.
Pharmacological (enzymatic) zonulysis
- 1.
- A.
- II.
Lens removal
- A.
Total (intracapsular)
- 1.
Capsule forceps
- 2.
Suction erysiphake
- 3.
Cryoextraction
- 1.
- B.
Partial (extracapsular)
- 1.
Anterior capsulotomy/capsulectomy
- a.
Discontinuous
- b.
Continuous (capsulorrhexis)
- c.
Linear
- a.
- 2.
Nucleus removal
- a.
Assembled delivery (large incision)
- (1)
Expression (“push”)
- (2)
Extraction (“pull”)
- (1)
- b.
Disassembled extraction
- (1)
Phacosection
- (2)
Phacoemulsification-aspiration
- (a)
Ultrasound
- (i)
linear
- (ii)
torsional
- (i)
- (b)
Laser
- (c)
Water jet
- (d)
Impeller
- (a)
- (1)
- a.
- 3.
Cortex removal
- a.
Irrigation
- b.
Aspiration
- a.
- 1.
- A.
- III.
Lens replacement (intraocular lens implantation)
- A.
Locations
- 1.
Anterior chamber
- a.
Angle fixation
- b.
Iris fixation
- a.
- 2.
Pupil
- 3.
Posterior chamber
- a.
Iris fixation (sutured or enclavated)
- b.
Ciliary sulcus (sutured or unsutured)
- a.
- 4.
Lens capsule
- a.
Anterior capsule
- (1)
Haptic sulcus/optic bag
- (2)
Optic posterior chamber/haptic bag
- (1)
- b.
Intracapsular (“in the bag placement”)
- c.
Posterior capsule (haptic bag/optic Berger’s space)
- a.
- 5.
Pars plana (sutured)
- 1.
- B.
Optic materials
- 1.
Hydrophobic
- a.
Polymethyl methacrylate (PMMA)
- b.
Silicone
- c.
Acrylic
- a.
- 2.
Hydrophilic
- a.
Poly hydroxyethyl methacrylate (poly-HEMA)
- b.
Acrylic
- c.
Collagen-copolymer
- a.
- 1.
- C.
Optic types
- 1.
Monofocal
- a.
Spherical
- (1)
Plus
- (2)
Minus
- (1)
- b.
Toric
- c.
Telescopic
- d.
Prismatic
- a.
- 2.
Multifocal
- 3.
Accommodative
- 1.
- A.
- IV.
Lens enhancement: reversal of presbyopia by scleral expansion
- A.
Ciliary cerclage
- B.
Radial anterior ciliary sclerotomy
- A.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
