A prospective, longitudinal, observational, pilot study was done in Minia University hospital from April 2019 to December 2020 on 30 myopic eyes after obtaining consent from all the participants in the study with approval of the ethical committee of faculty of medicine of Minia University. The included patients had aged more than 18 years with a degree of myopia of more than – 8 diopters (D) with astigmatism less than – 2 D with stable refraction over the past year, Anterior chamber depth (ACD) more than or equal 3 mm, corneal endothelium count more than 2500 cells/mm2 with intraocular pressure (IOP) less than 21 mmHg. Patients with ACD less than 3 mm, keratoconus, glaucoma, corneal or retinal disease and low endothelial cells count less than 2500 cells/mm2 were excluded from the study. Also, patients with diabetes mellitus (DM) and autoimmune diseases were excluded.
Complete ophthalmological examination including examination of the anterior segment of the eye with the slit-lamp (Sun Kingdom, China). Uncorrected (UCDVA) and best-corrected visual acuity (BCDVA) was assessed by the LogMAR chart. Tonometry with Goldmann applanation tonometer (Keeler, UK). Refraction with Nidek® auto refractometer and with retinoscopy. Endothelial cell count by specular microscopy (NIDEK, CEM-530, JAPAN), corneal topography (Oculus Pentacam, Oculus Co., Irvine, California, United States).
For calculation of the power and size of the IPCL, spherical and cylindrical errors, keratometric readings, pachymetry, ACD and, white to white diameter (WTW) were needed.
The IPCL surgery
V2.0 design was used with no need for PI. Done by the same surgeon under general anesthesia (GA), preoperatively, pupillary dilatation was done by tropicamide 1 % and phenylephrine hydrochloride 2.5%. Loading of the IPCL was done before opening the eye, the IPCL was implanted via a 2.8 mm clear temporal corneal incision after injection of viscoelastic. After implantation, the footplates were tucked under the iris. Injection of intracameral miotic then wash of viscoelastic. Finally wound hydration was done.
Postoperative treatment consisted of topical antibiotic as topical moxifloxacin and topical anti-inflammatory as prednisolone acetate 1 % in tapering doses. Topical antiglaucoma eye drops as beta-blockers were used in some cases.
Using RTVue XR 100 Avanti spectral domain-OCT device, version 2015 (Optovue, Inc., Fremont, California) ™.
AS-OCT was performed in dim illumination after introduction of the patient data with selection of the examination type (the enhanced anterior segment single protocol) from the machine software. The video image was centered on the limbus in the 4 quadrants (nasal, temporal, superior, inferior) and the scan head was moved towards the patient until the anterior chamber angle view became focused, the patient was asked to look into the imaging aperture and look at the center of the blue star-shaped target and not at the moving light then images were captured by pressing the joystick or checkmark button. Firstly, the scleral spur identification, which was established as the point of change in the aqueous corneoscleral interface which appears as the sclera's inward protrusion. 3 measurements were taken from each image:
1- Anterior chamber angle (ACA) (TIA750): The trabecular-iris angle estimated at 750 µm from the scleral spur with the apex in the iris recess and the angle arms passing through a point on the trabecular meshwork and the point on the iris perpendicularly opposite.
2- Angle opening distance at 750 µm (AOD750): 750 µm from the scleral spur, the distance between the posterior corneal surface and the anterior iris surface on a line perpendicular to the trabecular meshwork.
3-Trabecular-iris space area at 750 µm (TISA): A trapezoid surface area with the following boundaries: anterior, the opening angle 750 µm away from the scleral spur; posterior, the line traced from the scleral spur perpendicular to the iris plane of the inner scleral wall; superior, the inner corneoscleral wall; and inferior, the surface of the iris.
- The vault was also manually measured by drawing a line from the middle of the IPCL's back surface and the crystalline lens's anterior surface.
SPSS statistics software (version 20 for Windows; SPSS Inc., Chicago, IL) was used for data analysis. Number (N) and percentage (%) were used for qualitative data and mean and standard deviation (SD) were used for quantitative data. For comparison of dependent quantitative data, the dependent (paired) sample t- test was used. Probability (p) was considered significant if p < 0.05.