Safety and Suitability of ICL for Correction of Refractive Errors Without the Use of Dispersive OVDs

Overview

The goal of this observational study is to test whether surgeries for lenses designed to be implanted in the eye to correct refractive error can be done without the need for using viscoelastic substances that are used routinely nowadays to make it easier to introduce them inside the human eye and protect the inside of the eye during the operation. The main question it aims to answer is that is it safe to do the surgery without using them? to answer this question researchers will access recorded data of patients that underwent refractive surgeries in a private clinic since 2017 and compare them as two groups: those who underwent the traditional procedures and those who had it without the use of dispersive viscoelastics in regard to their vision before and after surgery, their ocular pressure and biomicroscopic analysis of the inside of their corneas before and after surgery.

Records of patients that had undergone ICL implantation surgery in Al-Ferdows private eye hospital in Baghdad between 2017 and 2023 were accessed. Two groups of patients were identified, for the first group the ICL was implanted with the use of both dispersive and cohesive OVDs (traditional OVD group) and for the second one a novel method of implantation was used without utilizing dispersive OVD (reduced OVD) group. Both types of surgery were done by the same surgeon and in the same settings. The operative notes of the OVD group were as follows: under topical anesthesia if the ICL is toric, manual corneal marking is done in the sitting position using pendular marker. After loading of the ICL, two-step clear corneal main incision 2.8 mm in width with a bit long track of 1.5-2 mm to enhance its valve action was fashioned. Intracameral injection of dispersive OVD. The ICL was implanted with mouth-to-mouth technique. Anterior chamber reformation with cohesive OVD, then haptics are gently pushed behind the iris using an olive-tipped manipulator, ensuring alignment to proper axis in case of toric ICL, otherwise spherical ICL is placed directly at 180° axis. After that, AC (anterior chamber) wash with irrigation/aspiration is performed then stromal hydration was done to seal the surgical wound. In the reduced OVD group, modification to the traditional method involved omitting the step of dispersive OVD injection and instead utilizing Intracameral injection of 1:1 mixture of 1:1000 adrenaline and 2% lidocaine in an overfilling manner. All other surgical steps are performed in an identical manner. The study was ethically approved by the institutional review committee at the respective hospital and a similar committee at the college of medicine of university of Basrah according to the local guidelines and protocols. Written informed consent was obtained from each patient before the surgery. The study followed tenets of declaration of Helsinki. For both groups, records involving preoperative and postoperative assessments such as uncorrected and best corrected visual acuity, refractive error quantification both objectively utilizing an autorefractometer autorefractor Nidek ARK 1 (Nidek Inc, Gamagori, Japan) and subjectively as manifest refraction, clinical slit-lamp examination notes, intraocular pressure with non-contact air puff tonometer Topcon CT-1P (Topcon Inc., Tokyo, Japan), AC depth assessment by Pentacam Scheimpflug (Oculus Optikgeräte GmbH Inc., Wetzlar, Germany), specular microscopy study of corneal endothelial cells (endothelial cell density (ECD), coefficient of variation (CV) and hexagonality) using Topcon SP-1p Specular Microscope (Topcon Corporation, Tokyo, Japan), were accessed and analyzed using the latest software in SPSS. Patients with missing or incomplete data were excluded from the study. Exclusion criteria also included patients with severe ocular surface disease, unstable refraction, glaucoma, cataract, retinal detachment and uveitis. Unpaired t test or Mann-Whitney test was used to compare the two groups according to fulfilled statistical assumptions. Significance was considered at P value less than 0.05.