**1. Introduction**

Ocular surgery is usually performed in patients lying in a supine position with the surgical microscope perpendicular to the surgical plane.

However, this usual position may not be possible if the patient cannot remain in a supine position due to medical conditions. Rotating the optical axis of the microscope perpendicular to the eye is one possible solution for such procedures in patients undergoing surgery in an inclined position [1–4]. However, it is very challenging to perform surgeries when the microscope rotation exceeds 30◦ in practice, because a greater rotation is incompatible with the posture of the surgeon, who needs to be able to look through the microscope oculars during surgery.

The three-dimensional (3D) digital visualization system was recently evaluated and shown to be safe for ocular surgery [5–7]. The ocular-free design of the 3D system makes it possible for the surgeon to adopt a much more ergonomic posture during surgery and may release the limitations on the axis of the microscope rotation.

**Citation:** Sandali, O.; Tahiri Joutei Hassani, R.; Armia Balamoun, A.; El Sanharawi, M.; Borderie, V. Facilitating Role of the 3D Viewing System in Tilted Microscope Positions for Cataract Surgery in Patients Unable to Lie Flat. *J. Clin. Med.* **2022**, *11*, 1865. https://doi.org/ 10.3390/jcm11071865

Academic Editor: Nobuyuki Shoji

Received: 22 February 2022 Accepted: 26 March 2022 Published: 28 March 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

In this study, we report the utility of the 3D viewing system in tilted microscope positions for cataract surgery in challenging positions in 15 consecutive patients unable to remain in a supine position.

#### **2. Surgical Technique**

This report included consecutive patients undergoing cataract surgery in an inclined position for medical reasons, at Guillaume de Varye Hospital (Bourges, France) between January 2021 and November 2021. These patients were either unable to remain in a supine position or found this position very uncomfortable. The study was approved by the ethics committee of our institution and was performed in accordance with the Declaration of Helsinki.

All the interventions were performed by the same experienced surgeon (O.S.) with the Constellation® (Alcon Surgical, Ft. Worth, TX, USA) surgical system and the 3D digital visualization system (NGENUITY®, Alcon, Fort Worth, TX, USA), connected to a (Lumera 700 Carl Zeiss Meditec, Jena, Germany) microscope.

All the operations were performed under topical anesthesia. The patients were lying in a standard reclining cataract surgical chair, the back of which was reclined to a position in which the patient felt comfortable, to ensure that the surgical conditions were good.

The surgical chair was lowered as much as possible, to ensure that the patient's eye was located at about the generator cassette level. Depending on the angle at which the patient was tilted, the microscope was tilted such that it was parallel to the eye and its optical axis was perpendicular to the surgical plane, providing good visualization (Figure 1).

**Figure 1.** Patient suffering from orthopnea undergoing cataract surgery in an inclined position. The microscope was tilted perpendicular to the surgical plane.

The surgeon sat, as usual, behind the patients and a 2.2 mm principal corneal incision was made in the superotemporal quadrant for right eyes, and in the superonasal quadrant for left eyes, avoiding the eyebrow (Figure 2). The nucleus was emulsified by the divide and conquer technique (Video S1 Supplementary Material).

**Figure 2.** Surgeon positioning behind patients who underwent cataract surgery in inclined positions ((**a**): patient inclined in a 30◦ position. (**b**): patient inclined in a 65◦ position).

Pre-operative cataract grading was assessed according to a simplified nuclear classification score based on the posterior nuclear color appearance [8].

Red reflex perception, the impression of depth, the operating time, the need for corneal suture, operative complications, and surgeon comfort (scale: 1–3; 1: comfortable, 2: mild discomfort, 3: uncomfortable) were assessed with a questionnaire.
