**4. Preoperative ocular evaluation**

The detailed preoperative examination of clinical ophthalmologic conditions should be done to help patients achieve good results because a successful presbyopia correcting solution often based on a health eye. Choosing the right presbyopia correcting IOLs should be considered for biometry, keratometry, topography and pupil reactivity and other eye comorbidities.

### **4.1 Corneal astigmatism**

It is important to correct astigmatism in the premium IOLs surgery. The postoperative astigmatism should be less than 0.75D in the eye which bifocal or trifocal IOL had been implanted. Over 1.5 diopter postoperative astigmatism is one of main reasons for patient's dissatisfaction following surgery. The larger amounts of postoperative astigmatism will cause decreasing visual function of multifocal IOLs, increasing some optical phenomena [23].

The keratometry, autorefraction and corneal topography/tomography are the helpful preoperative diagnostic devices to evaluate patients with astigmatism to select the astigmatism correction option——limbal relaxing incisions (LRI) or toric presbyopia correcting IOLs. The corneal topography provides more detailed useful information on the regularity of the corneal astigmatism than conventional keratometry or optical biometry (IOLMaster, Lenstar). Tomography devices like Pentacam address the posterior corneal astigmatism or total corneal astigmatism which deliver to more accuracy correcting astigmatism in multifocal IOLs cases (**Figure 5**). Another important issue in management of corneal astigmatism is surgical induced astigmatism which results from flattening in the meridian of the incision and steepening 90° away. The surgeon should evaluate his surgical induced astigmatism (SIA) via standard astigmatic vector analysis or online calculator [24].

**139**

**4.2 Keratoconus**

**Figure 5.**

is preferred [29, 30].

the keratoconus cases.

*Successful Premium Multifocal IOL Surgery: Key Issues and Pearls*

Small amounts of regular astigmatism can be corrected with manual LRI or femtosecond laser LRI, the later method achieved a higher correction and lower postoperative cylinder than manual LRI patients [25]. LRI correction is determined

The toric presbyopia correcting IOLs is more predictable treatment than LRI, providing good uncorrected vision at distance and either intermediate or near, depending on the built-in add [26, 27]. The toric IOL can be calculated with online program provided by the IOL manufacturer. Most of online calculators had taken into consideration anterior corneal astigmatism, posterior corneal astigmatism and SIA, and choosing IOL toricity by using the total corneal refractive power or in-built nomogram. Some new technologies had been developed to improve toric multifocal IOLs solution flow to achieve the better outcome, including intraoperative wavefront aberrometry (ORA system, Alcon), Image Guided System like

Corneal with irregular astigmatism is contraindicator for multifocal IOLs. Irregular astigmatism often caused by previous corneal infection disease, trauma, dystrophies, pterygium or severe dry eye. In these conditions, poor higher-order root-mean square (HO RMS) corneal wavefront error over a 6-mm zone will present in Pentacam or other aberrometry. If this value exceeds 0.50 μm, the patient will

Cataract surgery in keratoconic eyes is not uncommon issue which need to be addressed. Proper IOL selection must be individualized for each keratoconic patient to achieve an optimal outcome. Even for monofocal IOLs implantation, IOLs power calculation is a challenging issue due to the abnormalities of both anterior and posterior corneal surface [28]. Some studies have shown promising results about toric IOL in nonprogress keratoconic patients, while in progress cases the combined procedures including intracorneal ring segment (ICRS), cross linking and toric IOL

But multifocal IOLs should been avoided because the loss of contrast sensitivity associated with multifocal lenses will be magnified by the corneal irregularity. Previous corneal surgical history like pterygium, PKP is an important etiology for irregular astigmatism. IOL solution in these cases is similar to

have a high risk of halos and glare with a multifocal IOL (**Figure 6**).

by Abbott Medical Optics' LRI calculator (http://www.lricalculator.com).

Verion(Alcon), Callisto Eye (Carl Zeiss Meditec).

*DOI: http://dx.doi.org/10.5772/intechopen.96182*

*Regular corneal astigmatism and total corneal astigmatism.*

*Successful Premium Multifocal IOL Surgery: Key Issues and Pearls DOI: http://dx.doi.org/10.5772/intechopen.96182*

*Current Cataract Surgical Techniques*

be rule out of the candidates. The diffractive or refractive multifocal IOLs will increased the photic phenomena in dim environment, while the accommodation

The detailed preoperative examination of clinical ophthalmologic conditions should be done to help patients achieve good results because a successful presbyopia correcting solution often based on a health eye. Choosing the right presbyopia correcting IOLs should be considered for biometry, keratometry, topography and pupil

It is important to correct astigmatism in the premium IOLs surgery. The postoperative astigmatism should be less than 0.75D in the eye which bifocal or trifocal IOL had been implanted. Over 1.5 diopter postoperative astigmatism is one of main reasons for patient's dissatisfaction following surgery. The larger amounts of postoperative astigmatism will cause decreasing visual function of multifocal IOLs,

The keratometry, autorefraction and corneal topography/tomography are the helpful preoperative diagnostic devices to evaluate patients with astigmatism to select the astigmatism correction option——limbal relaxing incisions (LRI) or toric presbyopia correcting IOLs. The corneal topography provides more detailed useful information on the regularity of the corneal astigmatism than conventional keratometry or optical biometry (IOLMaster, Lenstar). Tomography devices like Pentacam address the posterior corneal astigmatism or total corneal astigmatism which deliver to more accuracy correcting astigmatism in multifocal IOLs cases (**Figure 5**). Another important issue in management of corneal astigmatism is surgical induced astigmatism which results from flattening in the meridian of the incision and steepening 90° away. The surgeon should evaluate his surgical induced astigmatism (SIA) via standard astigmatic vector analysis or online calculator [24].

IOL or monovision based on the monofocal IOLs should be better choice.

**4. Preoperative ocular evaluation**

*Preoperative questionnaire (courtesy of dr. Takashi).*

reactivity and other eye comorbidities.

increasing some optical phenomena [23].

**4.1 Corneal astigmatism**

**Figure 4.**

**138**

**Figure 5.** *Regular corneal astigmatism and total corneal astigmatism.*

Small amounts of regular astigmatism can be corrected with manual LRI or femtosecond laser LRI, the later method achieved a higher correction and lower postoperative cylinder than manual LRI patients [25]. LRI correction is determined by Abbott Medical Optics' LRI calculator (http://www.lricalculator.com).

The toric presbyopia correcting IOLs is more predictable treatment than LRI, providing good uncorrected vision at distance and either intermediate or near, depending on the built-in add [26, 27]. The toric IOL can be calculated with online program provided by the IOL manufacturer. Most of online calculators had taken into consideration anterior corneal astigmatism, posterior corneal astigmatism and SIA, and choosing IOL toricity by using the total corneal refractive power or in-built nomogram. Some new technologies had been developed to improve toric multifocal IOLs solution flow to achieve the better outcome, including intraoperative wavefront aberrometry (ORA system, Alcon), Image Guided System like Verion(Alcon), Callisto Eye (Carl Zeiss Meditec).

Corneal with irregular astigmatism is contraindicator for multifocal IOLs. Irregular astigmatism often caused by previous corneal infection disease, trauma, dystrophies, pterygium or severe dry eye. In these conditions, poor higher-order root-mean square (HO RMS) corneal wavefront error over a 6-mm zone will present in Pentacam or other aberrometry. If this value exceeds 0.50 μm, the patient will have a high risk of halos and glare with a multifocal IOL (**Figure 6**).

#### **4.2 Keratoconus**

Cataract surgery in keratoconic eyes is not uncommon issue which need to be addressed. Proper IOL selection must be individualized for each keratoconic patient to achieve an optimal outcome. Even for monofocal IOLs implantation, IOLs power calculation is a challenging issue due to the abnormalities of both anterior and posterior corneal surface [28]. Some studies have shown promising results about toric IOL in nonprogress keratoconic patients, while in progress cases the combined procedures including intracorneal ring segment (ICRS), cross linking and toric IOL is preferred [29, 30].

But multifocal IOLs should been avoided because the loss of contrast sensitivity associated with multifocal lenses will be magnified by the corneal irregularity. Previous corneal surgical history like pterygium, PKP is an important etiology for irregular astigmatism. IOL solution in these cases is similar to the keratoconus cases.

**Figure 6.** *Corneal irregular astigmatism with history of corneal refractive surgery. HO RMS is 0.679 um, over 0.50 um.*

#### **4.3 Previous corneal refractive surgery**

Patients who have undergone myopic or hyperopic LASIK/PRK/RK tend to select the premium IOLs with higher expectations regarding the refractive outcome. But intraocular lens power calculation for these patients is challenging because it is difficult to calculate the true corneal power. The optical quality of corneal is another factor to consider for IOL selection. The high order aberration is increased after the laser myopic corneal which led to decrease the visual result of multifocal IOLs and increase the photophobia like halo, glare [31]. If cornea high order aberration is higher than 1 μm especially it caused by corneal irregularities, the presence of irregular astigmatism/coma, a decentered/uneven treatment bed, the patient should not be considered as good candidate for multifocal IOL implantation [5].

The post-myopic LASIK patients who had previous treatment was less then −6 D, ablation bed was fairly well centered with no or little irregular astigmatism and did not experience problems with night vision can be considered to use presbyopia correcting IOLs. [32] Some surgeon preferred EDOF IOls (Symfony, Johnson and Johnson Vision) in these patients, because its larger size central optic and higher light transmission provides an enhanced contrast sensitivity as compared with other refractive or diffractive multifocal IOls [33, 34]. If monovision was already created with LASIK or PRK, and monovision is probably a much better way to go.

In the patients who had underwent the hyperopia laser correctio have increased negative spherical aberration and are best suited for aberration-free multifocal IOLs or IOLs with positive spherical aberration. The accommodating IOL was recommend by some surgeon if multifocal IOLs and EDOF IOLs were intolerant by the significant corneal coma.

A monofocal IOL is often the best choice in patients with previous RK who often had irregular corneal or increased corneal aberration. Now, pinhole IOLs (Xtrafocus, Morcher GmbH) is an effective presbyopia correcting solution for irregular astigmatism RK patients. It can correct of postoperative residual refraction and provide an elongated depth of focus [35].

**141**

outcomes [39].

*Successful Premium Multifocal IOL Surgery: Key Issues and Pearls*

erative discussion to management the patient expectation.

visual quality after the premium IOLs implantation [16].

keratometry and other ocular biometry parameter.

**4.5 Pupil size, angle kappa and angle alpha**

Understanding the patient's ocular surface is of critical importance because ocular surface pathologic features can lead to false corneal power, induced astigmatism

Preoperative dry eye will lead to post-operative refractive surprise, blur vision and foreign body sensation, excessive tearing, and photophobia that makes patients unhappy [36]. Surgeon and assistor should address the OSD issue as part of preop-

The most common OSD is meibomian gland dysfunction and dye eye. A thorough evaluation of the lids and lashes, testing for lacrimal gland function and tear film should be included in preoperative examination. A symptoms questionnaire

The treatment is based on severity and subtype of OSD. Steroid and preservative-free lubrication can be used for improving the corneal surface. Other therapy included moisture chamber glass, punctal occlusion, and oral omega fatty acid supplements. If the ocular surface condition is not improved after advanced therapies, the multifocal IOLs is not recommend due to significantly high and persistent postoperative OSD symptoms [37]. The low tear breakup time, increased meibomian gland dropout will increase the high order aberration leading to decrease the

Besides OSD, there are some corneal disease inducing irregular astigmatism will affect the premium IOLs section, such as addressing anterior basement membrane dystrophy (ABMD), epithelial basement membrane dystrophy, Salzmann nodular degeneration (SND). Appropriate management of these corneal abnormalities should be performed before cataract surgery in order to gain the reliable corneal

Pupil size, shape and centration also have a significant influence on presbyopic IOL surgery. In diffractive multifocal IOLs, the difference of diffractive step height determined the different light energy distribution in far, intermediate and near distance. Light energy distribution of the multifocal IOLs (MIOLs) varies with different aperture. For apodized diffractive IOLs, the near reading will become difficulty due to light energy goes more to distance in dim illumination. It suggested eyes implanted with multifocal IOLs should have a photopic pupil size of 3.5 mm or less and mesopic pupil size of 5 mm or less [38]. The average pupil size of photopic and mesopic are correlated with contrast sensitivity defocus curve [38]. The photophobia phenomenon like glare and halo also more complained in the large pupil patients. For the asymmetric refractive multifocal IOLs, the pupil size is an important parameter which had a significant negative subjective impact for

Angle kappa (K) is defined as the angular difference between the visual axis and the pupillary axis while angle a refers to the angular distance between the visual axis and the optical axis. Though postoperative far, intermediate, and near vision is not affected by angle K which does not include the fixation point, large angle K might play a role in the decentration of multifocal intraocular lenses (IOLs), potentially resulting in the incident of glare and hola increasing which led to patient satisfaction with multifocal IOLs [40–43]. A well-centered lens in the visual axis is vital for proper functioning of presbyopic IOLs. Chord between the pupil centration and visual axis is the value to be evaluated for IOL location. It was suggested that a MIOL is unacceptable for use if the k value is greater than half of the diameter of

*DOI: http://dx.doi.org/10.5772/intechopen.96182*

also helps to capture OSD before surgery.

**4.4 Ocular surface disease (OSD)**

and unstable bad visual acuity.
