**6. Phakic IOL**

Special considerations in cases selected for RLE include the following:

complications, and the problem of pseudophakic presbyopia [10].

A clear corneal incision and continuous curvilinear capsulorhexis (CCC)

Irrigation/aspiration is performed to remove all viscoelastic material

Cystoid macular edema in the first few weeks after surgery

Choroidal neovascular membrane (CNV) formation

PCO, which can develop from months to years after the surgical procedure

further surgical maneuvers and reduces surgical time

IOL insertion. After IOL insertion, bimanual

incisions is hydrated to assist self-sealing.

possible incision.

228 Advances in Eye Surgery

**5.2. Surgical technique [10]**

*5.2.1. Topical anesthesia*

*5.2.2. Phacoemulsification*

Irrigation/aspiration

for IOL insertion

*5.2.3. Complications*

IOLs.

Post-RLE retinal detachment

Myopic macular degeneration

syndrome

The best approach to RLE surgery includes minimally invasive surgery, through the smallest

Specific informed consent for RLE different to different to the one used for cataract surgery must be provided and will include information about potential refractive benefits and

Hydrodissection: cortical cleaving hydrodissection is performed in two separate distal quadrants with decompression of the anterior chamber in order to avoid capsular block

Prechopping (optional): although the nucleus is not hard in RLE, prechopping facilitates

The nucleus is divided based on the technique used: prechopping, chopping, or grooving,

An adequate viscoelastic is injected deep in the capsular bag to reform the bag and prepare it

A preservative-free antibiotic is injected into the anterior chamber, and then the stroma at the

A decrease in twilight vision (with halo perception and glare) after implantation of multifocal

This is the insertion of an additional synthetic lens in front of the natural lens, placed either behind the iris in the ciliary sulcus or clipped to the iris in the anterior chamber.

Implantation of IOLs in the phakic eye (phakic intraocular lense, pIOL) is a relatively new technique to correct high ametropia.

pIOLs are used for correcting moderate and high ametropias and allowing maintenance of accommodation while offering good quality of vision, some reversibility of the procedure, and possible management of postoperative error [21, 39, 50, 72, 79, 123]. Among the IOLs are the implantable Collamer lens (ICL, Staar Surgical, Monrovia, CA), a foldable posterior chamber IOL, the veriflex lens (Verflex Phakic IOL), an iris-claw lens with hydrophobic polysiloxane foldable design. Implantation of both types of pIOLs is increasingly popular because it is technically undemanding while offering high predictability and a good safety profile.

Implantation of pIOLs is a reversible refractive procedure, preserving the patient's accommo‐ dative function with minimal induction of HOAs compared with corneal photoablative procedures [86].

Corneal ablation surgical procedures such as PRK or LASIK laser are usually the preferred options by refractive surgeons for correcting refractive errors [86]. However, the range of safe dioptric correction for these procedures has been progressively limited due to the mid- and long-term complications observed, particularly in cases of high refractive error, such as keratectasia [95], corneal haze [105], regression [8], dry eye [119], or poor postoperative visual quality [55, 89]. It has been shown that photoablative refractive surgery in high ametropia can lead to a significant increase in ocular aberrations [89] and decrease in visual perform‐ ance [55]. Furthermore, corneal photoablation has a decreased predictability for the correc‐ tion of high refractive error because of the unknown and unpredictable effects on corneal biomechanics [98].

Intraocular refractive procedures have become a safe, efficient, and predictable alternative for treating high ametropias when the use of corneal photoablative procedures is not possible or high risk [86].

The progress of intraocular refractive surgery is due to advances made in IOL designs, surgical tools and procedures, and viscoelastic substances, [7].

The advantages of implantation of pIOLs are:

**•** a reversible refractive procedure and


pIOLs may be divided into anterior chamber and posterior chamber lenses, with anterior chamber lenses being further divided into angle-supported and iris-fixated [86].

Angle-supported pIOLs were first implanted in 1986. Initial designs induced significant rates of complications (corneal endothelial cell loss, chronic uveitis or pupil ovalization). These lenses have shown good refractive results in the long term [58, 86, 87].

Despite this, as an intraocular procedure, it has potential-associated complications such as cataract, chronic uveitis, pupil ovalization, corneal endothelial cell loss, pigmentary dispersion syndrome, pupillary block glaucoma, astigmatism, or endophthalmitis [34].

#### **6.1. Indications of phakic lenses**

Patients with high myopia and who are poor candidates for laser correction.

#### *6.1.1. Criteria*

Age: 21–45 years with ACD of 3.0 mm or greater and Shaffer grade II as determined by gonioscopy

Myopia ranging from −3 to −20 D

Astigmatism less than or equal to 2.5 D

Stable refraction (less than 0.5 D change for 6 months)

Clear crystalline lens

Ametropia not suitable, appropriate for excimer laser surgery

Unsatisfactory vision, intolerance of contact lenses, or spectacles

A minimum endothelial cell density

No ocular pathology such as corneal disorders, glaucoma, uveitis, maculopathy

*6.1.2. Surgical procedure for anterior chamber angle-supported phakic IOL*

Anterior chamber phakic IOL implantation can be performed under typical or peribulbar anesthesia

Pilocarpine is instilled in the eye 30 min before surgery to protect the crystalline lens at the time of IOL implantation

Creating a superior scleral tunnel or a temporal clear corneal incision (2-6.5 mm, of size, according to the IOL model)

The anterior chamber is filled with cohesive viscoelastic

The lens is introduced toward the angle from the incision (the first footplace is inserted in the iridocorneal angle, the second haptic is then placed, avoiding having their folding over the haptic)

The lens is then rotated with a lens dialer to the meridian in which the pupil is best centered in relation to the IOL optic

A peripheral iridectomy is performed

The incision is closed

**•** a preservation of the accommodative function with

**6.1. Indications of phakic lenses**

Myopia ranging from −3 to −20 D

Astigmatism less than or equal to 2.5 D

A minimum endothelial cell density

Stable refraction (less than 0.5 D change for 6 months)

Ametropia not suitable, appropriate for excimer laser surgery

Unsatisfactory vision, intolerance of contact lenses, or spectacles

*6.1.2. Surgical procedure for anterior chamber angle-supported phakic IOL*

The anterior chamber is filled with cohesive viscoelastic

No ocular pathology such as corneal disorders, glaucoma, uveitis, maculopathy

Anterior chamber phakic IOL implantation can be performed under typical or peribulbar

Pilocarpine is instilled in the eye 30 min before surgery to protect the crystalline lens at the

Creating a superior scleral tunnel or a temporal clear corneal incision (2-6.5 mm, of size,

*6.1.1. Criteria*

230 Advances in Eye Surgery

gonioscopy

anesthesia

time of IOL implantation

according to the IOL model)

Clear crystalline lens

**•** a minimal induction of HOAs compared with corneal photoablative procedures [86, 102]. pIOLs may be divided into anterior chamber and posterior chamber lenses, with anterior

Angle-supported pIOLs were first implanted in 1986. Initial designs induced significant rates of complications (corneal endothelial cell loss, chronic uveitis or pupil ovalization). These

Despite this, as an intraocular procedure, it has potential-associated complications such as cataract, chronic uveitis, pupil ovalization, corneal endothelial cell loss, pigmentary dispersion

Age: 21–45 years with ACD of 3.0 mm or greater and Shaffer grade II as determined by

chamber lenses being further divided into angle-supported and iris-fixated [86].

lenses have shown good refractive results in the long term [58, 86, 87].

syndrome, pupillary block glaucoma, astigmatism, or endophthalmitis [34].

Patients with high myopia and who are poor candidates for laser correction.

Removal of the viscoelastic

Topical antibiotics and corticosteroids are applied for times daily for 4–6 weeks

*6.1.3. Surgical procedure for iris-fixated phakic IOLs*

Preoperative application of topical pilocarpine

Corneal, limbal, or scleral tunnel incision (at least 5.3 or 6.3 mm)

The "claw" haptics are fixated to the iris by enclavation by two side-port incisions at 10 and 2 o'clock

The lens is implanted vertically through the incision, and rotated and centered in front of the pupil with haptics at 3 and 9 o'clock positions

The anterior chamber is filled cohesive OVD material

Watertight wound closure

Removing of the OVD material

Antibiotics and corticosteroids are prescribed for 2–4 weeks.

*6.1.4. Surgical technique for posterior chamber phakic IOLs*

Topical mydriatics (combination cyclopentolate and phenylephrine), 30 min before surgery

Topical or peribulbar anesthesia

A 2.0–3.0 mm temporal clear corneal tunnel

Placement of cohesive OVD

The posterior chamber IOL is introduced into the anterior chamber

Each footplace is then placed one after the other beneath the iris

Intraoperative iridectomy (or 2 peripheral Nd:YAG laser iridotomis 2 weeks before surgery)

Removing of the OVD material

Acetylcholine chloride is injected

Antibiotics and steroids eyedrops are used three times a day for 1 week with tapered doses for 3 weeks and tropicamide 0.5% two times a day for 2 days.

There are a number of studies evaluating the outcomes obtained with the different models of ICL, and therefore, there is a complete characterization of the refractive outcomes and complications resulting from the implantation of this pIOL [2, 3, 4, 5, 47, 70, 90, 104].

#### **6.2. Preoperative assessment and patient selection for pIOLs implantation [86]**

A complete ophthalmological examination is performed before the suy and will include:


The patient must be properly inform about the procedure and risks of the surgery.Spherical hydrophilic contact lenses, toric hydrophilic and rigid gas permeable contact lenses must be discontinued during a period of at least 1week before the preoperative examination, [80]. The refractive error stability during at least 1 year before the intervention must be confirmed. The principal indication for pIOL implantation includes prior contraindication of corneal refractive surgery for myopic or hyperopic refractive error correction (including postsurgical central keratometry below 36 D, RSB of <250 mm or residual central corneal thickness below 400 µm after the programmed laser ablation) [86].

Contraindications of this type of implant for refractive error correction include the following:

Age under 18 years old (except in certain cases of anisometropic amblyopia with intolerance to contact lenses and noncompliance with other less invasive treatment options) [9], previous intraocular surgery, ACD (corneal endothelium-anterior surface of the crystalline lens) <3 mm, glaucoma, history of uveitis, lenticular opacity, nontreated peripheral retinal lesions, scotopic pupillary diameter of >7 mm, neuro-ophthalmological disease, pregnancy or breastfeeding, and unrealistic expectations [17, 57].

Also, any condition associated to a potential zonular weakening and fragility of the ciliary processes should be also considered as a contraindication for the implantation of PRL, such as history of ocular trauma with secondary zonular damage, Marfan' s syndrome diagnosis [42]. A preoperative evaluation of the zonule by means of ultrasound technology is indicated [86].

#### **6.3. Results**

Antibiotics and steroids eyedrops are used three times a day for 1 week with tapered doses

There are a number of studies evaluating the outcomes obtained with the different models of ICL, and therefore, there is a complete characterization of the refractive outcomes and

complications resulting from the implantation of this pIOL [2, 3, 4, 5, 47, 70, 90, 104].

A complete ophthalmological examination is performed before the suy and will include:

**•** Visual acuities (uncorrected and best-corrected) visual acuity (using preferably optotypes

**•** Intraocular pressure measurement (preferably Goldmann tonometry); scotopic pupillome‐ try; corneal topography; biometric analysis (axial length, white-to-white (WTW) distance, and ACD); corneal endothelial analysis by means of a specular microscopy; binocularity

The patient must be properly inform about the procedure and risks of the surgery.Spherical hydrophilic contact lenses, toric hydrophilic and rigid gas permeable contact lenses must be discontinued during a period of at least 1week before the preoperative examination, [80]. The refractive error stability during at least 1 year before the intervention must be confirmed. The principal indication for pIOL implantation includes prior contraindication of corneal refractive surgery for myopic or hyperopic refractive error correction (including postsurgical central keratometry below 36 D, RSB of <250 mm or residual central corneal thickness below 400 µm

Contraindications of this type of implant for refractive error correction include the following:

Age under 18 years old (except in certain cases of anisometropic amblyopia with intolerance to contact lenses and noncompliance with other less invasive treatment options) [9], previous intraocular surgery, ACD (corneal endothelium-anterior surface of the crystalline lens) <3 mm, glaucoma, history of uveitis, lenticular opacity, nontreated peripheral retinal lesions, scotopic pupillary diameter of >7 mm, neuro-ophthalmological disease, pregnancy or breastfeeding,

Also, any condition associated to a potential zonular weakening and fragility of the ciliary processes should be also considered as a contraindication for the implantation of PRL, such as history of ocular trauma with secondary zonular damage, Marfan' s syndrome diagnosis [42]. A preoperative evaluation of the zonule by means of ultrasound technology is indicated [86].

);

**6.2. Preoperative assessment and patient selection for pIOLs implantation [86]**

for 3 weeks and tropicamide 0.5% two times a day for 2 days.

in logMAR scale under photopic conditions, 85 cd/m2

**•** Refraction (objective, subjective, and cycloplegic);

**•** a comprehensive clinical history;

232 Advances in Eye Surgery

**•** Biomicroscopy of anterior segment

evaluation; and fundus evaluation.

after the programmed laser ablation) [86].

and unrealistic expectations [17, 57].

#### *6.3.1. Results of angle-supported anterior chamber pIOLs [64]*

Anterior chamber pIOLs generally demonstrate good predictability, efficacy, and safety. However, there is a tendency toward undercorrection of the refractive error [58, 120].

#### *6.3.2. Results of iris-fixated anterior chamber pIOLs [64]*

Several studies with long follow-up demonstrated good predictability, efficacy, and safety of the nontoric and toric pIOL models. With the toric pIOL models, larger amount of preoperative astigmatism can be managed successfully [6, 38, 49, 51, 121].

#### *6.3.3. Results of posterior chamber pIOLs [64]*

Visual acuity, predictability, efficacy, and safety of the ICL (Staar Surgical Co.) and the phakic refractive lens (PRL; Carl Zeiss Meditec) posterior chamber pIOL models are good. In a United States Food and Drug Administration (FDA) study, the ICL pIOL showed good functional results with a low complication rate (ICL, 2004). In a prospective study comparing matched populations of laser in situ keratomileusis (LASIK) and Visian ICL implantation, the ICL performed better than LASIK in almost all measures of safety, efficacy, predictability, and stability (Sanders, 2007). In a few case reports, results with the toric posterior chamber pIOL have been shown [63, 64]. Schallhorn et al. [64] report better results with the toric ICL than with conventional PRK in a randomized prospective comparison of safety, efficacy, predicta‐ bility, and stability. In summary, pIOLs show good refractive and clinical results. They demonstrate reversibility, high optical quality, potential gain in visual acuity in myopic patients due to retinal magnification, and correction is not limited by corneal thickness or topography. With proper anatomical conditions (especially sufficient ACD), pIOLs also show good refractive and clinical results in hyperopic patients [22]. Phakic IOLs preserve corneal architecture, asphericity, and accommodation. With recent innovations in the design of toric pIOLs, spherocylindrical correction is also feasible. However, pIOL implantation is not without complications. The spectrum of common and rare complications with each type of pIOL is presented in the following section.

#### **6.4. Complications**

#### *6.4.1. General complications of intraocular surgery [64]*

With the increasing use of topical or parabulbar anesthesia, complications due to anesthesia such as retrobulbar hemorrhage, penetration of the globe, or life-threatening systemic side effects from accidental injection into the optic nerve are very rare.

Because implantation of a pIOL is an intraocular procedure, it bears a potential risk for the development of postoperative endophthalmitis. The risk for this complication in general cataract surgery with implantation of a posterior chamber IOL is 0.1–0.7% with an optimal antiseptic perioperative treatment regimen.

*6.4.2. Complications of angle-supported anterior chamber pIOL*

Loss of corneal endothelial cells Pupil ovalization/iris retraction Optical quality, glare, halos Surgically induced astigmatism Pigment dispersion or IOL deposits Chronic inflammation or uveitis Intraocular pressure elevation/pupillary block glaucoma pIOL rotation Cataractogenesis Retinal detachment Oddities

*6.4.3. Complications of iris-fixated anterior chamber pIOL*

Optical quality, glare, halos Surgically induced astigmatism

Loss of corneal endothelial cells

Pigment dispersion/lens deposits

Intraocular pressure elevation

pIOL rotation

Cataractogenesis

Retinal detachment

Oddities

#### *6.4.4. Complications of posterior chamber pIOL*

Complications for the ICL and PRL are similar and are related to the position of the pIOL between the rear surface of the iris and the front surface of the crystalline lens. Complications such as cataractogenesis, pupillary bloc, and glaucoma are due to pIOL design materials (www.ecavolunteer.org).

Optical quality, glare, halos

Surgically induced astigmatism Loss of corneal endothelial cells Pigment dispersion/IOL deposits/intraocular pressure elevation Chronic inflammation/uveitis Pupil ovalization/iris retraction Pupillary block/malignant glaucoma Decentration/incorrect size/pIOL rotation Cataractogenesis Retinal detachment Oddity: zonular dehiscence
