Diagnostic imaging of the ciliary body: Technologies, outcomes, and future perspectives

The ciliary body (CB) is part of the uvea and is a complex, highly specialized structure with multiple functions and significant relationships with nearby structures. Its functions include the aqueous humor (AH) production in the ciliary processes, the regulation of the AH output through the uveoscleral pathway, and accommodation, which depends on the ciliary muscle. Also, the CB is an important determinant of angle width as it forms part of the ciliary sulcus. Until recently, knowledge of the CB was based on histological studies. However, this structure can currently be assessed in vivo using imaging techniques such as ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT). Both techniques have shown good reproducibility of their measurements allowing for quantification of CB dimensions and their localization. In effect, studies have shown a larger CB in myopia and its diminishing size with age. Swept-source OCT devices offer fast, non-invasive high-resolution imaging allowing the identification of multiple structures. UBM requires contact and is uncomfortable for the patient. However, this technique offers deeper imaging and therefore remains the gold standard for assessing the posterior chamber, ciliary processes, or zonula. The clinical utility of CB imaging includes its assessment in different types of glaucoma such as angle-closure, malignant or plateau iris. Diagnostic CB imaging is also invaluable for the assessment of ciliochoroidal detachment when suspected, the position after the implantation of a pre-crystalline or sulcus-sutured lenses, diagnosis or monitoring of cysts or tumors, sclerotomies after retinal surgery, intermediate uveitis, or accommodation.

Vitreous incarceration in sutured vs non-sutured sclerotomies after 25-gauge macular surgery

OBJECTIVES

To study the patterns of vitreous incarceration in sutured vs non-sutured sclerotomies in patients subjected to 25-gauge macular surgery.

METHODS

A prospective study of 135 eyes affected by epiretinal membrane or macular hole. Vitreal disposition was evaluated via ultrasound biomicroscopy (UBM) at the sclerotomy sites between 30 and 40 days after surgery, once the tamponade had completely disappeared.

RESULTS

In total, 349 sclerotomies (86.2%) of 99 patients were non-sutured while 56 sclerotomies (13.8%) of 36 patients were sutured at the end of the surgical procedure. Among the 36 patients with sutured sclerotomies, 15 out of 36 (41.6%) had at least two sclerotomies sutured. All the sclerotomy sites were evaluated (405 sclerotomies). Sclerotomy suture was significantly associated with a less aggressive pattern of vitreal incarceration (OR: 0.16, 95% CI: 0.07-0.35, p < 0.001). Compared to preoperative values, day 1 post operative IOP was not significantly different in patients with sutured sclerotomies, while patients with non-sutured sclerotomies had a significantly lower day 1 post operative IOP.

CONCLUSIONS

In 25-gauge macular surgery, UBM evaluation documented a higher rate of postoperative vitreous incarceration in the non-sutured sclerotomies, confirming the previously postulated role of the residual vitreous, left at the end of the surgery, in closing the sclerotomy site.

VITREOUS INCARCERATION IN SCLEROTOMIES AFTER VALVED 23-, 25-, OR 27-GAUGE AND NONVALVED 23- OR 25-GAUGE MACULAR SURGERY

PURPOSE

To study the patterns of vitreous incarceration at sclerotomy sites by ultrasound biomicroscopy in patients subjected to valved or nonvalved small-gauge pars plana vitrectomy.

METHODS

A prospective comparative study of 88 eyes affected by epiretinal membrane and macular hole. Patients were divided into four groups: valved or nonvalved 23-gauge (16 eyes each) and valved or nonvalved 25-gauge (20 eyes each); their vitreal disposition was compared by ultrasound biomicroscopy. Vitreal disposition was also assessed in 16 eyes of 16 patients subjected to valved 27-gauge pars plana vitrectomy.

RESULTS

Three vitreal patterns were identified: P0 (vitreous not visible or vitreous strand distant from the sclerotomy site), P1 (vitreous strand parallel to and in contact with the sclerotomy site), and P2 (vitreous strand entrapped in the sclerotomy site). The effect of valved trocar use on vitreous incarceration seemed to be somewhat beneficial, but no statistically significant effect could be shown (odds ratio: 0.85, 95% confidence interval: 0.42-1.74, P = 0.657). Similarly, no differences in vitreous incarceration were shown among vitrectomy gauges (23, 25, or 27) both in a model including valved trocars only (P = 0.858) and in a model with all available data (P = 0.935).

CONCLUSION

In 23- and 25-gauge macular surgeries, postoperative vitreous incarceration does not seem to be reduced using valved cannulas and was similar to that observed in 27-gauge surgery.

Assessment of Closure Competency of Sutureless Vitrectomy Sclerotomies After Scleral Hydration

PURPOSE

To assess the influence that hydration applied on the sclerotomy edges may have on incisional closure resistance after transconjunctival sutureless vitrectomy (TSV).

METHODS

Experimental, randomized and observer-masked study in which 23-gauge TSV was performed in 80 cadaveric pig eyes. Once each vitrectomy was finished, hydration with balanced salt solution (BSS) was applied on the sclerotomy edges of one of the superior incision sites; no maneuver was performed on the other superior sclerotomy. Intraocular pressure (IOP) was gradually increased by means of the vitrectomy system (Accurus; Alcon Laboratories, TX) until one of the superior sclerotomies opened, allowing internal ocular solution to escape.

RESULTS

In 45% of cases (36 of 80 eyes), sclerotomies subjected to hydration allowed intraocular fluid escape (p = 0.43). There were no differences when comparing opening pressure values of hydrated and non-hydrated sclerotomies (p = 0.19).

CONCLUSIONS

Scleral hydration did not demonstrate increase in the sclerotomy closure resistance in our experimental model. Given the widespread use of sutureless TSV around the world, the results obtained in our research, in spite of being negative, may contribute to the knowledge of the behavior of sutureless sclerotomies.

Influence of the source of incisional vitreous incarceration on sclerotomy closure competency after transconjunctival sutureless vitrectomy

PURPOSE

To evaluate the influence that the origin of incisional vitreous incarceration may have on the presence of postoperative conjunctival blebs over sclerotomies after transconjunctival sutureless vitrectomy (TSV). Blebs are formed by incisional leakage due to incompetent closure.

METHODS

Twenty-three-gauge TSV was performed in 83 cadaveric pig eyes. Once each vitrectomy was finished, ultrasound biomicroscopy (UBM) was used to assess the presence of postoperative conjunctival blebs over the sclerotomy sites, as well as the existence of vitreous incarcerated in incisions. Vitreous strands may come from the perisclerotomy area, running parallel to the sclera toward the inner hole of the sclerotomies, or may radiate from the core of the vitreous cavity.

RESULTS

Vitreous entrapment was found in 73.9% of the sclerotomies; 43.4% of the incisions showed vitreous strands coming parallel to the sclera (12.9% of them showed conjunctival bleb), 19.7% of the wounds presented vitreous aiming toward the core of the vitreous cavity (2% of them had conjunctival bleb) and 10.8% of the entrances presented both vitreous incarceration sources (none of them showed bleb). Incisions with vitreous entrapment parallel to the sclera were associated with a significantly greater sclerotomy leakage rate.

CONCLUSIONS

Sclerotomies with vitreous incarceration coming from the core of the vitreous cavity showed a greater incisional closure competency than that observed in incisions with vitreous entrapment coming from the pericannular area; if these results were confirmed in humans, different postoperative suture rates may be expected on sclerotomies according to the vitrectomy degree performed in different areas of the vitreous cavity.

Intraoperative endoscopic observation of sclerotomy site after cannula removal for 23-gauge vitrectomy

BACKGROUND

The purpose of this study was to determine the incidence of vitreous incarceration in sclerotomy after cannula removal during 23-gauge vitrectomy.

METHODS

Thirty-seven eyes underwent 23-gauge sutureless vitrectomy. Oblique sclerotomies were made parallel to the limbus and tangentially to the sclera. Once past the trocar sleeve, the angle was changed to 90 degrees perpendicular to the surface and the trocar and cannula inserted. Vitreous gel was removed until the intraocular edge of the infusion cannula was free from the gel. The cannula was extracted with insertion of a light probe. The sclerotomy site was evaluated endoscopically through another cannula in 32 eyes; in five eyes, another infusion tube was inserted into the cannula to maintain intraocular pressure, the original infusion was removed, and the sclerotomy site observed.

RESULTS

No vitreous incarceration occurred in 30 (94%) eyes when one cannula was removed with insertion of a light probe, and minimal incarceration occurred in two (6%) eyes. No incarceration occurred in five eyes with observation of the infusion site.

CONCLUSION

The incidence of vitreous incarceration is low when a light probe or vitreous cutter is inserted. Inserting the light probe through the cannula during its removal and creating an oblique sclerotomy may reduce vitreous incarceration.

Influence of sclerotomy use on vitreous incarceration in an experimental model of vitrectomized eye

PURPOSE

To evaluate the influence of sclerotomy use during vitrectomy (vitreous cutter, illumination probe, or infusion-line entrance) on postoperative vitreous incarceration using an experimental model of vitrectomized eye.

MATERIALS AND METHODS

Experimental, randomized, and observer-masked study in which 23-gauge transconjunctival sutureless vitrectomy was performed in cadaveric pig eyes. Postoperative incisional vitreous entrapment was evaluated by direct visualization. No vitreous incarceration was classified as grade 0 (G0), thin vitreous entrapment was classified as grade 1 (G1), and thick vitreous strands as grade 2 (G2).

RESULTS

A total of 46 eyes were included. Vitreous incarceration was detected in 91.3% (43.5% G1, 47.8% G2) of the sclerotomies used by the vitreous cutter probe, 95.7% (45.7% G1, 50% G2) of the illumination-pipe entrances, and 93.5% (45.7% G1, 47.8% G2) of the infusion-line incisions. No statistical differences were found when comparing incisional vitreous incarceration after vitrectomy according to sclerotomy use.

CONCLUSION

Different manipulation of the sclerotomies, depending on their use, does not seem to influence postvitrectomy vitreous entrapment in our experimental model.