Response to the Letter to the Editor: Comments on “Adequate Silicone Oil Tamponade by Utilizing the Space of Anterior Segment for Complicated Retinal Detachment: Technique, Efficacy, and Safety”

Thank you for the critical comments on our study.¹ We would like to clarified that adequate silicone oil tamponade (ASOT) is proposed for complex retinal detachment (RD), especially those with inferior retinal breaks, and it may serve as a complement to, rather than a substitute for, current surgical techniques.

We agree that ASOT only increases the amount of silicone oil (SO) in the anterior chamber (AC). The volume of AC and vitreous cavity (VC) is 0.26 mL and 4.5 mL regarding to standard model eyes. The increase of SO by ASOT, therefore, should be calculated as 5.8% (0.26/4.5). It is inappropriate to calculate the volume ratio of AC/VC using different criteria. We have also assessed the volume of aqueous humor in patients with RD repair before their SO removal using a 1-mL syringe in recent days. In eyes with nearly normal axial length, the withdrawing volume of AC appears to be: eyes receiving ASOT > combined phaco and regular SOT > regular silicone oil tamponade (SOT) alone. Moreover, the volume of AC in 1 high myopic eye was 0.35 mL, indicating that the volume of AC increases and contributes to similar AC/VC ratio in high myopic eyes.

Inadequate SO tamponade will cause decreased tamponade effect, leading to unsealed inferior breaks and redetachment. In such condition, discussing about intraocular lens (IOL) implantation into the capsular bag does not make sense. The adhesion of anterior and posterior capsule can be separated sometimes and in-bag IOL implantation is possible if extensive anterior capsule polishing and appropriate anti-inflammation were done. Even though the capsular bag cannot be reopened, some kinds of IOL can be implanted in the ciliary sulcus without significant deviation.

We do not quite agree with raising the pressure to force additional SO into the VC. Because liquids are incompressible, this procedure increases few SO in the VC. Instead, it may raise intraocular pressure and damage the optic nerve. We suggested an inferior peripheral iridotomy of 1 mm in oval shape, which had mild impact on iris appearance or visual interruptions (Supplementary Digital Content, Fig. 1, https://links.lww.com/APJO/A151). Because severe postoperative inflammation may increase the risk of occlusion of iridotomy or posterior synechiae, appropriate anti-inflammation is essential.

Literatures using model eye filling experiment (Supplementary Digital Content, Fig. 2, https://links.lww.com/APJO/A152) demonstrated that for 2.5 mL (40%) and less of SO there was no tamponade effect on inner surface of the sphere. Conversely, when the sphere is near-filled (97%, 6/6.2), the tamponade effect increased strikingly when the volume of SO increases slightly and even additional 0.1 mL SO can significantly increase the tamponade angles.² We believe ASOT can increase at least 0.2 mL SO to reach a more pronounced tamponade effect.

It is almost impossible for patients to always keep in bed. ASOT ensures a wider angle of endotamponade no matter what position the patient holds. Patients required prone positioning in early postoperation just to allow the aqueous humor to enter the AC and force the SO to migrate to the VC. When this is achieved, the aqueous humor will normally enter the AC rather than the VC because of the pressure drag from the SO bubble.

We agree with using AC paracentesis to release part of the AC volume and increase the volume of the VC. However, it only has partial ASOT filling effect and for eyes with high myopia or potential zonular fiber damage, this procedure may cause further damage. ASOT might have less impact on the zonular fibers.

We reiterate that ASOT just serves as a complement to current surgical strategies for complex RD. We welcome counterparts and experts to further test the feasibility and clinical significance of this procedure and to discuss any relevant issues with us.