A New and Easier Approach to Preserflo MicroShunt Implantation

Figures & data

Table 1 Overview of the MicroShunt Device Surgical Procedure Recommended by the Manufacturer

Different Steps of the Surgical Procedure

1.Conjunctival peritomy: Performed approximately 3 to 4 mm in length between the superior rectus muscles and either the medial or lateral rectus. 2.Careful dissection of the Tenon’s layer freeing all attachments to the underlying sclera to create a deep pocket. 3.Hemostasis by using bipolar cautery. 4.Application of MMC, placed into the subconjunctival space, using LASIK sponges. MMC is subsequently wash of the pocket with balanced saline solution (BSS). 5.Marking the sclera 3 mm from the limbus with the scleral marker. 6.Dissecting a 1 mm wide scleral tunnel with the supplied micro knife. 7.Sliding of the 25G needle through the scleral pocket and entering the anterior chamber, remaining parallel to the iris plane. 8.Threading the micro shunt into the tunnel, wedging the planar fins into the scleral pocket. 9.Flushing the device and confirming the flow of humor through the distal end of the device. 10.Closing the Tenon’s layer and the conjunctiva.

Figure 1 Overview of the main steps of the new surgical technique. (A) The needle is aimed to pierce the sclera starting 3 mm from the limbus. (B) Once the needle has reached the limbus it is pushed downwards. (C) The needle goes into the anterior chamber. (D) Once the tunnel is created with the triangular blade, the path of the needle used to enter the anterior chamber may be not perfectly coaxial with the tunnel, thus creating a false passage.

Table 2 Main Demographic and Clinical Characteristics of the Study Population

Variable	N=15 Eyes
Age, years
Median (IqR)	76.0 (71.8 to 84.3)
Sex, n (%)
Women	6 (40.0)
Men	9 (60.0)
Eye, n (%)
Right	8 (53.3)
Left	7 (46.7)
Functional, n (%)
One-eyed	10 (66.7)
Two-eyed	5 (33.3)
Lens status, n (%)
Phakic	3 (20)
Pseudophakic	12 (80)
Glaucoma Type, n (%)
Primary open angle glaucoma	15 (100)
Previous surgery, n (%)
Trabeculectomy	1 (0.7)
SCAI, n (%)
Yes	8 (53.3)
No	7 (46.7)
Pre-operative IOP, mm Hg
Median (IqR)	28.0 (27.0 to 32.5)
Pre-operative medications
Median (IqR)	3.0 (2.2 to 3.0)
Visual field, dB
Mean Defect
Mean (95% CI)	−11.7 (−14.9 to −8.5)
Pattern SD
Mean (95% CI)	6.8 (5.9 to 7.7)
BCDVA
Median (IqR)	0.70 (0.43 to 0.78)

Abbreviations: SD, standard deviation; BCDVA, best corrected distant visual acuity; SCAI, systemic carbonic anhydrase inhibitors; IOP, intraocular pressure; CI, confidence interval.

Figure 2 Median intraocular pressure over the course of the study follow-up. Vertical bars represent interquartile range. *p < 0.005 as compared to baseline (Friedman test and post hoc analysis for pairwise comparisons were done with the Conover method).

Figure 3 Overview of the median best corrected distance visual acuity (BCDVA) over the course of the study follow-up. Vertical bars represent interquartile range. *p < 0.01 as compared to baseline (Friedman test and post hoc analysis for pairwise comparisons were done with the Conover method).

Abbreviations: n.s., not significant.