*2.2.2 Slit lamp examination of the anterior segments of the eye*

Eyelids, lacrimal drainage system, cornea, conjunctiva, iris, pupil, anterior chamber, and lens should be evaluated in the first preoperative examination. In detail, certain findings for each anatomical structure should be taken into account and could encourage surgeons to perform some types of presbyopic corrections or discourage them from performing other surgical techniques. In addition, some eye pathologies should be addressed before the surgery.


dysfunction should be treated preoperatively, since tear-film abnormalities may influence postoperative visual outcomes leading to suboptimal visual quality and performance, regardless of the type of IOL to be implanted. Slit lamp evaluation of corneal endothelium should not be omitted. Corneal dystrophies, such as Fuchs' corneal dystrophy, as well as corneal scars (central or peripheral), pterygium and keratoconus signs should be taken into consideration for the selection of the most appropriate presbyopia correction method.

	- *Optic nerve:* Any abnormality of the optic nerve could influence the surgeon's decision for the IOL type selection.
	- *Macula:* The macular anatomy should be assessed. The presence of acquired macular disorders including age-related macular degeneration (ARMD) findings and macular edema, or hereditary macular disorders, such as Stargardt's disease and retinitis pigmentosa, could be considered as relative or absolute contraindications for pseudophakic presbyopic corrections. The evaluation of the appropriateness of a pseudophakic presbyopic correction in the presence of a macular disease should depend on the stability of the disease, the expected progression over time, and the availability and usefulness of its treatment.
	- *Rest fundus:* Retinal ischemia, vitreous retinal traction, lattice degeneration, and macular hole should be sought especially in diabetic patients.

**97**

*Pseudophakic Presbyopic Corrections*

examination.

tive error.

*DOI: http://dx.doi.org/10.5772/intechopen.96528*

**2.3 Additional diagnostic procedures**

*2.3.1 Automatic refraction*

*2.3.2 Optical biometry*

sponds to the correct patient.

*2.3.3 A-scan ultrasound biometry*

*2.3.4 Corneal pachymetry*

corneal edema [26].

*2.2.4 Intraocular pressure (IOP) measurement*

The measurement of the IOP should be part of the basic ophthalmological

Measurements taken by an automatic kerato-refractometer can be co-evaluated with manifest refraction and corneal topography for the confirmation of the refrac-

Optical biometry, which is based on monochromatic light-emitting diodes, [16] including partial coherence interferometry (PCI) [e.g. IOLMaster 500 (Carl Zeiss Meditec AG, Jena, Germany)] and swept source OCT (ss-OCT) [eg. IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany), Anterion (Heidelberg Engineering, Heidelberg, Germany)], serves as highly reliable method for AL (in mm), ACD (in mm) and keratometry (in diopters) determination. In comparison with standard keratometry, total keratometry measured with ss-OCT (IOLMaster 700) is a new measurement for the assessment of anterior and posterior corneal curvatures that seems to show higher accuracy in IOL power calculation and better refractive outcomes in eyes with or without previous laser refractive surgery [17–19]. As a result, it has been established as the most common preoperative examination performed to calculate the IOL power. According to the selected technique and patient, the postoperative refractive target is plano, low myopia or low hyperopia [20]. A variety of formulas have been used for the most accurate IOL power calculation. Since it has been found that inaccurate biometry is the most common cause of residual postoperative refractive error, [21] some factors should be taken into account; among them, interocular consistency in AL and K values, appropriate formula for each case, and outliers [22]. Last but not least, preoperatively, the surgeon should check and confirm that the biometry corre-

Although A-scan biometry is less accurate and requires more operator skills to ensure consistent accuracy in comparison with optical biometry, it can be used in presence of dense cataract or corneal edema when the optical biometry cannot take measurements [23]. However, for the optimization of a-scan results, the immersion instead of the applanation (contact) technique could be chosen, since the former has better repeatability and higher accuracy than the latter [24, 25].

Ultrasonic pachymetry may contribute to the assessment of overall endothelial function in corneas with a diseased endothelium or with borderline low endothelial cell counts, however, corneal central thickness is not correlated with endothelial cell numerical density within the physiological range. Specifically, an increased preoperative thickness might increase the risk for postoperative clinical
