**2. Indications**

Modern cataract surgery has evolved the role of secondary intraocular lens implantation since there is now less incidence of surgical aphakia after cataract surgery [2]. With current technology and improved cataract surgery technique, the most common reason for secondary lens implantation is IOL exchange. The rates of IOL exchange also have declined over the years with recent studies showing

rates of 0.34–0.77% [2–4]. ACIOL explantation is most commonly due to corneal decompensation and inflammation [5, 6]. PCIOL explantation is most commonly due to IOL decentration and dislocation [7]. IOL dislocation can be due to zonular dehiscence from trauma, previous complicated surgery, or conditions predisposing to zonular instability such as pseudoexfoliation syndrome and Marfan's syndrome.

Uveitis-hyphema-glaucoma (UGH) syndrome is a complication of iris chafing of an IOL. Most commonly this is due to a single-piece IOL with a haptic outside of the capsular bag that comes in contact with posterior iris tissue. IOL chafing of iris tissue leads to iris transillumination defects, pigment dispersion, microhyphema/hyphema, and glaucoma. Treatment of UGH often requires IOL removal with placement of a secondary IOL although in some cases the haptic in the sulcus alone can be cut and removed.

In recent years, advancements in IOL calculations, cataract surgery technology and technique have improved refractive outcomes. Patient visual expectations after cataract surgery have increased and now, in some cases, IOL exchanges are performed for unexpected refractive outcomes, dissatisfaction with multifocal lenses, and dysphotopsias following cataract surgery. The rates of IOL exchange due to patient dissatisfaction in one study showed an increase from 7.8% in 2005 to 21% in 2014 [3]. In 2005, no patients underwent IOL exchange for unsatisfactory refractive outcomes in the absence of optical aberrations but in 2014, 42% of IOL exchanges were due to unsatisfactory refractive outcomes alone.

#### **3. Preoperative evaluation**

Prior to consideration of secondary intraocular lens implantation, a thorough pre-operative history is required. In particular, details of the prior cataract removal including intraoperative complications, type of IOL implanted, location of the IOL implant and the presence of other ocular hardware including glaucoma drainage devices are important pieces of information to gather before secondary IOL surgery. To this end, review of prior operative reports and medical records is a critical element of every preoperative evaluation.

A thorough examination of the anterior and posterior segment is required to plan for a secondary IOL implantation. The conjunctiva and scleral should be examined to identify any prior incisional glaucoma surgery or devices. Corneal health should be evaluated to determine if an ACIOL is a viable option. Specular microscopy or pachymetry can be obtained as needed to assess corneal endothelial health. Anterior chamber depth should be evaluated as a narrow/shallow chamber might preclude safe ACIOL placement. The presence of vitreous prolapse in the anterior chamber should be noted as well as the integrity of the iris and capsule. Of note, high frequency ultrasound has shown to be better than slit lamp examination in assessing capsular support for sulcus IOL implantation [8]. If there is an intraocular lens in place, the type of lens and degree of dislocation should be assessed. The optic nerve and retina should be thoroughly examined to evaluate for any other ocular comorbidities that can limit vision potential or require treatment at the time of secondary IOL implantation. Finally, vision potential with a reliable manifest refraction is important to gauge the potential benefit of secondary IOL implantation.

#### **4. Contact lens and aphakic glasses**

Aphakic spectacles are a non-invasive option for bilateral aphakia although they are a sub-optimal solution for unilateral aphakia due to induced aniseikonia.

**125**

in more detail.

*Secondary Intraocular Lens*

*DOI: http://dx.doi.org/10.5772/intechopen.89569*

questionable functional visual potential.

with a secondary IOL technique.

techniques.

IOLs, and ACIOLs.

cope with objects jumping in and out of their visual field.

**5. Determination of anatomic location of secondary IOL**

Aniseikonia is a significant difference in the perceived size of images between the two eyes. This difference in image sizes can be as large as 30% which makes fusion impossible [9]. Other drawbacks of aphakic spectacles are that they are heavy and have poor cosmesis since the lenses are thick centrally with significant magnification. Also, patients wearing aphakic lenses may notice a ring scotoma and have to

Extended-wear contact lenses can be an adequate option for managing binocular

Choosing the best location and technique for secondary IOL implantation can be a difficult one. No clear guidelines are established for secondary IOL implantation. In 2003, Wagoner et al. reviewed the literature on secondary IOL implantation [10]. In this paper, the authors found no evidence to claim superiority of any one technique or anatomic location for fixation. Since 2003, secondary IOL surgery has continued to evolve dramatically and still no clear evidence exists to guide surgeons. As Wagoner's paper noted, the most important factor often is the surgeon's comfort

There are however, some recommendations in ruling out certain anatomic locations for IOL fixation. For example, poor corneal endothelial status and/or abnormal angle/iris anatomy should discourage anterior chamber IOL implantation. Lack of adequate iris support would rule out other iris-fixated approaches (sutured or iris-claw). Lack of posterior capsular support or a fibrosed anterior/ posterior capsule would rule out in-the-bag PCIOL placement. Sulcus intraocular lens implantation requires adequate anterior capsular support. Scleral abnormalities (i.e., Marfan's, scleral thinning, etc.) would rule out scleral fixation

In-the-bag posterior chamber intraocular lens implantation remains the best anatomic location for an intraocular lens. However, even if during secondary IOL implantation the aphakic eye has an intact posterior capsule, the anterior/ posterior capsule is typically fibrosed, preventing IOL implantation inside the capsular bag. Brunin et al. evaluated the complication rates, visual acuity and refractive outcomes of different intraocular lens implantation techniques [11]. Their study noted that capsular bag implantation had the best refractive outcomes followed by sulcus IOL with optic capture and sulcus IOL without optic capture. There was no difference between transscleral-sutured IOL, iris-fixated

If possible, in-the-bag implantation has the best outcomes given its closest proximity to normal anatomy. This requires a stable and intact capsular bag. If no posterior capsular exists but there is adequate anterior capsular support, sulcus IOL implantation can be performed, preferably with optic capture. However, if no capsular support exists, the guidelines for secondary IOL implantation remain controversial [12]. If a viable 3-piece IOL has been dislocated, the preference might be to reposition the lens with an iris-sutured or scleral fixation technique. Other options include ACIOL implantation, iris-fixation techniques, and scleral-fixation techniques. The following sections will explore these options

and monocular aphakia. Properly fitted contact lenses can be well-tolerated by patients and secondary IOL implantation can be avoided in patients who are happy with contact lens use. Some physicians argue that a trial of aphakic contact lenses should be required prior to secondary IOL implantation, especially in eyes with

#### *Secondary Intraocular Lens DOI: http://dx.doi.org/10.5772/intechopen.89569*

*Intraocular Lens*

rates of 0.34–0.77% [2–4]. ACIOL explantation is most commonly due to corneal decompensation and inflammation [5, 6]. PCIOL explantation is most commonly due to IOL decentration and dislocation [7]. IOL dislocation can be due to zonular dehiscence from trauma, previous complicated surgery, or conditions predisposing to zonular instability such as pseudoexfoliation syndrome and Marfan's syndrome. Uveitis-hyphema-glaucoma (UGH) syndrome is a complication of iris chafing of an IOL. Most commonly this is due to a single-piece IOL with a haptic outside of the capsular bag that comes in contact with posterior iris tissue. IOL chafing of iris tissue leads to iris transillumination defects, pigment dispersion, microhyphema/hyphema, and glaucoma. Treatment of UGH often requires IOL removal with placement of a secondary IOL although in some cases the haptic in the sulcus alone can be cut and removed. In recent years, advancements in IOL calculations, cataract surgery technology and technique have improved refractive outcomes. Patient visual expectations after cataract surgery have increased and now, in some cases, IOL exchanges are performed for unexpected refractive outcomes, dissatisfaction with multifocal lenses, and dysphotopsias following cataract surgery. The rates of IOL exchange due to patient dissatisfaction in one study showed an increase from 7.8% in 2005 to 21% in 2014 [3]. In 2005, no patients underwent IOL exchange for unsatisfactory refractive outcomes in the absence of optical aberrations but in 2014, 42% of IOL exchanges

Prior to consideration of secondary intraocular lens implantation, a thorough pre-operative history is required. In particular, details of the prior cataract removal including intraoperative complications, type of IOL implanted, location of the IOL implant and the presence of other ocular hardware including glaucoma drainage devices are important pieces of information to gather before secondary IOL surgery. To this end, review of prior operative reports and medical records is a critical ele-

A thorough examination of the anterior and posterior segment is required to plan for a secondary IOL implantation. The conjunctiva and scleral should be examined to identify any prior incisional glaucoma surgery or devices. Corneal health should be evaluated to determine if an ACIOL is a viable option. Specular microscopy or pachymetry can be obtained as needed to assess corneal endothelial health. Anterior chamber depth should be evaluated as a narrow/shallow chamber might preclude safe ACIOL placement. The presence of vitreous prolapse in the anterior chamber should be noted as well as the integrity of the iris and capsule. Of note, high frequency ultrasound has shown to be better than slit lamp examination in assessing capsular support for sulcus IOL implantation [8]. If there is an intraocular lens in place, the type of lens and degree of dislocation should be assessed. The optic nerve and retina should be thoroughly examined to evaluate for any other ocular comorbidities that can limit vision potential or require treatment at the time of secondary IOL implantation. Finally, vision potential with a reliable manifest refraction is important to gauge the potential benefit of secondary IOL

Aphakic spectacles are a non-invasive option for bilateral aphakia although they are a sub-optimal solution for unilateral aphakia due to induced aniseikonia.

were due to unsatisfactory refractive outcomes alone.

**3. Preoperative evaluation**

ment of every preoperative evaluation.

**4. Contact lens and aphakic glasses**

**124**

implantation.

Aniseikonia is a significant difference in the perceived size of images between the two eyes. This difference in image sizes can be as large as 30% which makes fusion impossible [9]. Other drawbacks of aphakic spectacles are that they are heavy and have poor cosmesis since the lenses are thick centrally with significant magnification. Also, patients wearing aphakic lenses may notice a ring scotoma and have to cope with objects jumping in and out of their visual field.

Extended-wear contact lenses can be an adequate option for managing binocular and monocular aphakia. Properly fitted contact lenses can be well-tolerated by patients and secondary IOL implantation can be avoided in patients who are happy with contact lens use. Some physicians argue that a trial of aphakic contact lenses should be required prior to secondary IOL implantation, especially in eyes with questionable functional visual potential.
