Assessment of Zonular Integrity in Phakic Eyes Following Pars Plana Vitrectomy Using Ultrasound Biomicroscopy: A Prospective Paired Eye Comparative Study

Purpose: To assess zonular integrity in phakic patients post vitrectomy using ultrasound biomicroscopy (UBM).

Design: Prospective, comparative, nonrandomized, double-masked, paired eye study.

Methods: We used ultrasound biomicroscopy (UBM) to evaluate phakic patients with a history of unilateral pars-plana vitrectomy.

Inclusion criteria: (1) phakic patients with history of pars plana vitrectomy in one eye as the only procedure; (2) normal unoperated fellow eye; and (3) complete gas or air resolution from the vitreous cavity at the time of UBM assessment.

Exclusion criteria: (1) monocular patients; (2) history of intraoperative lenticular trauma; (3) the use of silicone oil tamponade; (4) history of trauma or pseudoexfoliation in either eye; (5) history of other ocular conditions that can affect the integrity of zonules, such as uveitis or ectopia lentis; (6) eyes with extreme myopia or long axial length (> -8.00 D or >30.0 mm); (7) history of intravitreal injection in either eye; (8) age <18 years.

Technique: A high-frequency (50 MHz) UBM device was used by a masked technician to obtain radial section images from zonular bundles at 8 different clock positions. Image quality was assessed in real time, captured, and saved. Two experienced masked observers (H.C. and C.B.) then assessed the quality of the images and graded the zonular findings. Only patients with adequate studies have been included. A unique grading system that was specifically devised for this study was used as the following: (0) clear, well-defined zonule(s); (1) uneven, disrupted zonules or stretched zonules; and (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, 2 main groups were analyzed: vitrectomized eyes and healthy contralateral nonvitrectomized eyes. The mean total UBM score (TUS) from each group was compared and analyzed.

Results: Thirty-five patients were recruited into this study. Eleven patients were male and 24 were female. The mean age was 66.3 years. Thirty patients had vitrectomy for vitreomacular interface disorders (either macular hole or epiretinal membrane), 1 patient had vitreous hemorrhage and the remaining 4 patients had rhegmatogenous retinal detachments. With regard to tamponade agents, SF6 was used in 21 (60%) patients, air in 9 (26%) patients, and C3F8 in 5 (14%) patients. The mean TUS in the vitrectomized eyes was 2.28 (SD 1.83) vs 2.24 (SD 1.77) in the nonvitrectomized eyes (P = .9531). Overall, in the comparative analysis of mean scores based on 2 graders' assessments for each clock position in vitrectomized and nonvitrectomized eyes, there were no significant differences noted between the groups.

Conclusion: This study found no evidence for a difference in the mean total UBM score in eyes following vitrectomy when compared to their contralateral healthy, nonvitrectomized eyes. This likely indicates that vitrectomy may not affect the integrity of zonules in phakic patients, at least for patients with vitreomacular interface disorders undergoing uncomplicated surgery.