Fig. 28.1
Different periods of vaulting of the implanted toric ICL
Fig. 28.2
The ICL V4b IOL
Fig. 28.3
The ICL V4c iol
28.2.5 Recommended Criteria for the Toric ICL Implantation in KC Patients
Normal systemic history and normal physical examination results.
Absence of any history or physical signs of ocular disease with the exception of keratoconus and myopia.
Age between 20 and 45 years.
Best Spectacle Corrected visual acuity of 0.3 (20/60) or better in the eye to be treated.
Stable refraction for at least 12 months after corneal collagen cross-linking.
Clear central cornea.
Normal anterior segment with an anterior chamber depth of at least 2.80 mm.
Normal intraocular pressure.
28.2.6 Preoperative Assessment of Patients
Manifest (Subjective) and Cycloplegic (Objective) refraction.
Best spectacle corrected visual acuity:
Every single measure should be used to verify the subjective refraction before the calculation of the ICL power. The accurate subjective refraction in these cases is defined as the lowest sphere and cylinder values that give the best spectacle corrected visual acuity. These values together with the exact axis of the cylinder should be properly determined using all the available optometric tricks. The subjective refraction that gives the best spectacle corrected visual acuity should be checked in three consecutive monthly visits after at least 9 months of the CXL to get sure of the stability of refraction. The stability of the subjective refraction over the monthly visits is one of the most important parameters before planning to implant a toric ICL (TICL ) for those patients. It indicates the stability of the keratoconic state after the CXL, hence the stability of the visual outcome after the TICL implantation. One of the useful clinical tricks is to prescribe glasses for those patients and encourage them to wear their glasses for at least 2 weeks before ordering the ICL . Patient’s satisfaction and fair visual performance with the glasses before the TICL implantation are very good indicators of a good postoperative visual performance. Again, it is to be noted that there is usually a discrepancy between the value of the subjective and cycloplegic refraction in keratoconic eyes as a result of the corneal multifocality induced by the keratoconus [16].
Verification of the power of the sphere together with the power and exact axis of the cylinder give the best subjective spectacle corrected visual acuity is the key point of the success of the TICL implantation to give visual performance satisfaction for those patients.
Anterior chamber depth using IOL Master (Carl Zeiss, Jena, Germany), a Scheimpflug anterior segment imaging (e.g., Pentacam), or anterior segment OCT.
Corneal Curvature information (K readings).
White-to-white measurement using a Caliper and/or IOL Master (Carl Zeiss, Jena, Germany).
Assessment of anterior, posterior corneal surfaces and Anterior Chamber using a Scheimpflug camera system (e.g., Pentacam, Oculus Inc).
The ICL power can be calculated using the software ICL POWER CHOICE OF STAAR SURGICAL. The verified stable subjective refraction, as described earlier, is the one that is used to calculate the TICL power.
28.3 Surgical Technique
In order to dilate the pupil of the eye to be operated, 1 h before surgery, a Tropicamide 1 % (Mydriacyl, Alcon laboratories, Inc. Fort Worth, USA) and phenylephrine® ophthalmic solution 2.5 % (Alcon laboratories, Inc. Fort Worth, USA) are instilled every 15 min.
Marking the exact horizontal and vertical axes of the cornea at the slit lamp with a pen marker.
Checking and confirming that the pupil is fully dilated.
Confirmation of the received TICL power and diameter.
Reviewing the orientation diagram supplied by the manufacturer and establishing the implantation direction.
Cleaning of the operative site with Povidone Iodine (Betadine®).
Draping the patient and the operative site with sterile towels.
Preparing the TCL for loading into the injector cartridge:
Open the lens container
Hydrate the micro-Staar foam tip (STAAR Surgical) inside the ICL container
Wet the inside of the micro-Staar injector with BSS.
Lubricate the inside of the cartridge with viscoelastic Healon® (10 mg/mL Sodium hyaluronate; Abbott).
Getting the ICL from its container using the foam tip
Loading the ICL inside the cartridge under the microscope on the side table using the foam tip and the coaxial forceps (Janach, J3864.1, sold by STAAR)
Insertion of the foam tip inside the micro-Staar injector.
Finally load the cartridge inside the injector.
Cutting of the drape and exposing the operative eye with a self-retaining speculum.
Bores and Mendez tool is used to determine the proper axis for the lens position as indicated by the implantation diagram.
Marking the axis on the limbus using a surgical pen marker.
Performing two sideport incisions (paracentesis) one at 12:00 o’clock and one at 6:00 o’clock.
Temporal clear corneal tunnel of 3.00–3.2 mm with a disposable keratome after fixing the globe with 0.12 fixation forceps.
Injection of viscoelastic in the anterior chamber.
Insertion of the ICL using the injector.
Injection of viscoelastic on top of the lens in the anterior chamber.
Manipulating the distal haptic under the edge of the iris through the side port using an ICL special manipulator.
Manipulation of the proximal haptic under the iris edge through the main 3.2 mm incision.
ICL centration and rotation as necessary referring to the implantation guide.
Removal of the viscoelastic using Simcoe irrigation/Aspiration cannula.
Constriction of the pupil using Miochol-E (acetylcholine chloride intraocular solution) 1:100 with Electrolyte Diluent (Novartis, Switzerland).
Surgical iridectomy after pupil constriction is achieved using Vitrectomy cutter in case of implanting the V4b version of the ICL (not necessary in the new version of V4c ICL as it has a central hole).
Checking for wound leakage.
Instillation of antibiotic eye drops.
Removal of the drapes.
Antibiotic and corticosteroid drops four times daily for 10 days.
In cases of bilateral implantation, the second eye can be operated upon within the first postoperative week of the fellow eye.
Postoperative follow up should include; uncorrected visual acuity (UCVA ), CDVA, slit-lamp examination, Manifest and Cycloplegic refraction, funduscopy, and IOP measurements.
Assessment of the postooerative ICL vaulting should be done using the slit lamp, the anterior segmant OCT and/or a Scheimpflug camera system (Pentacam, Oculus Inc.).
28.4 Clinical Results
In a study that was conducted by our team [16] to assess the use of the toric ICL to correct the ametropia in the stable keratoconus patients after corneal collagen cross-linking, a prospective interventional clinical study included 16 eyes that we followed for more than 3 years which is considered the longest follow-up period for this technique in published data.
The results demonstrate the efficacy of the technique in restoring a good visual acuity for those patients having residual high sphere and cylinder after corneal collagen cross-linking.
28.4.1 Visual Acuity
Table 28.1 presents the different periods of the CDVA after the corneal cross-inking and ICL implantation, as noticed, the mean CDVA improved from 0.56 before cross-linking to >0.8 after 1 week of the ICL implantation, and this improvement was maintained throughout the follow-up period. The beta type 2 error was 0.0987.
Table 28.1
Different periods of the CDVA after the corneal cross-linking and ICL implantation
CDVA
Before cross-linking
Before ICL
After 7 days
After 1 month
After 6 months
After 1 year
After 3 years
Range
0.40–0.80
0.40–0.80
0.60–1.20
0.60–1.20
0.60–1.20
0.60–1.20
Mean ± SD
0.56 ± 0.13
0.63 ± 0.14
0.82 ± 0.16
0.87 ± 0.15
0.89 ± 0.17
0.89 ± 0.17
0.89 ± 0.17
Median
0.60
0.60
0.85
0.85
0.90
0.90
0.90
F (p)
Mean difference (p 1)
0.063* (0.002)
0.256* (<0.001)
0.306* (0.028)
0.325* (<0.001)
0.325* (<0.001)
0.325* (<0.001)
Mean difference (p 2)
0.194* (0.002)
0.244* (<0.001)
0.263* (<0.001)
0.263* (<0.001)
0.263 (<0.001)
Mean difference (p 3)
0.050* (0.032)
0.069 (0.139)
0.069 (0.139)
0.069 (0.139)
Mean difference (p 4)
0.019 (1.000)
0.019 (1.000)
0.019 (1.000)
Mean difference (p 5)
0.0 (−)
0.0 (−)
Mean difference (p 6)
0.0 (−)
Table 28.2 presents the difference between the CDVA before the surgery and the postoperative UDVA demonstrating a significant improvement in the visual acuity as the mean for the preoperative CDVA was 0.63 ± 0.14 and the mean of the postoperative UDVA was about 0.8 at 1 week and maintained throughout the rest of the follow-up or even got slightly better. The beta type 2 error was 0.0842.
Table 28.2
Difference between the CDVA before the surgery and the postoperative UDVA
UCVA
CDVA before ICL
After 7 days
After 1 month
After 6 months
After 1 year
After 3 years
Range
0.40–0.80
0.60–1.20
0.60–1.20
0.60–1.20
0.60–1.20
0.60–1.20
Mean ± SD
0.63 ± 0.14
0.79 ± 0.16
0.83 ± 0.16
0.85 ± 0.15
0.88 ± 0.18
0.88 ± 0.18
Median
0.60
0.80
0.80
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