Assessment of Zonular Integrity in Phakic Eyes post Vitrectomy Using Ultrasound Biomicroscopy (UBM) ; A Paired Eye Comparative Study
Authors: Mohammed Alfalah, Kenneth Eng, Catherine Birt, Peter Kertes. University of Toronto.
Author Disclosure Block: M. Alfalah: None. K. Eng: None. C. Birt: None. P. Kertes: None.
Purpose: To assess zonular integrity in phakic patients post vitrectomy using ultrasound biomicroscopy.
Study Design: Cross sectional, comparative, double masked, paired eye study.
Methods: We used ultrasound biomicroscopy (UBM) to evaluate phakic patients with history of unilateral pars-plana vitrectomy. Recruitment included patients presenting to the John and Liz Tory Eye Centre, Sunnybrook Health Sciences Centre Hospital in the period between January 1st - October 31st 2021. Inclusion criteria:1.Phakic patients with history of pars plana vitrectomy in one eye as the only procedure.2.Normal unoperated fellow eye3.Complete SF6/C3F8/air resolution for patients who had gas/air tamponade during their vitrectomy.4.Patients with silicone oil tamponade will be included if they are still phakic. Exclusion criteria:1. Monocular patients2. History of intraoperative lenticular trauma.3. History of trauma or pseudo-exfoliation in either eye. 4. History of other ocular conditions that can affect the integrity of zonules like uveitis or ectopia lentis.5. Eyes with extreme myopia/long axial length (more than -8.00 or more than 30.0 mm). 6.History of intravitreal injection in either eye. Technique:After obtaining a written informed consent, subjects have undergone complete undilated ophthalmic exam. High frequency (50 MHz) UBM device ( Accutome UBM Plus , model number: 24-6300-G , Software: 4.07.02-U for Windows 32 bit) was then used by a masked technician who has enough experience to operate the machine and obtain high quality images to visualize the zonules. Radial section images were obtained from zonular bundles at 12:00, 1:30, 3:00, 4:30, 6:00, 7:30, 9:00 and 10:30 clock positions. Images quality were assessed in real time, captured and saved.An experienced masked observer (CB) has then assessed the quality of images and graded the zonular findings. Only patients with adequate studies have been included. A unique grading system that has been specifically devised for this study has been used as the following: (0) clear, well-defined zonule(s); (1) uneven, disrupted zonules or stretched zonules; (2) extensive loss of zonules. Each clock hour was graded according to this system and the total score was then calculated for each eye. In the primary outcome, two main groups were analyzed; the vitrectomized and healthy contralateral non vitrectomized eyes. The mean total score from each group was compared and analyzed.
Results: Sixteen patients have been recruited into this study. Six patients were males and ten were females. The mean age was 65.75 (Range: 46-74). Thirteen patients had vitrectomy for vitreomacular interface disorders (either macular hole or epiretinal membrane), one patient had vitreous hemorrhage and two patients had rhegmatogenous retinal detachment. SF6 was used as vitreous substitute in 7 patients, air in 6 patients, C3F8 in 2 patients and silicon oil in one patient. The mean total score in the vitrectomized eyes was 4.94 versus 5.63 in the non vitrectomized eyes (p=0.378).
Conclusions: This study concludes that there was no evidence of zonular damage in eyes post vitrectomy when compared to their contralateral healthy and non-vitrectomized eyes.