Tamponade or filling effect: changes of forces in myopic eyes

Emulsification of Silicone Oils: Altering Factors and Possible Complications-A Narrative Review

Background: Endotamponade of the vitreous body with silicone oil is a common procedure, being the basis of many vitreoretinal surgeries. However, emulsification may happen, which is a clinically relevant adverse event of silicone oil use. Methods: This review provides a thorough analysis of the emulsification process. It focuses on describing factors affecting this event as well as its possible subsequent complications. Results: The viscosity of silicone oil, the duration of emulsification, the status of the lens and many other factors have an influence on the onset and intensity of emulsification. This phenomenon carries several risks for operated eyes such as increased intraocular pressure, keratopathy or structural changes to the retina. Conclusions: The use of modern imaging techniques, especially optical coherence tomography, enables faster detection of the emulsification process. This allows for an adequate clinical response and more accurate follow-up of the patient.

Impact of duration of silicone oil tamponade on foveal and parafoveal thickness in rhegmatogenous retinal detachment: a retrospective cohort study

PURPOSE

To detect and analyze the influence of the duration of tamponade with silicone oil on the foveal and parafoveal thickness in cases of rhegmatogenous retinal detachment.

METHODS

This is a retrospective cohort study of 64 eyes with rhegmatogenous retinal detachment in one eye who underwent pars plana vitrectomy (PPV) with silicone oil injection during the period between January 2019 and December 2021. The patients were divided into 2 groups. Group A with early removal of the silicone oil after 3-4 months and Group B with late removal of the silicone oil (SOR) after 6-8 months. The 2 groups were compared as regards the central foveal (CFT) and parafoveal (PFT) thickness changes from baseline, just before SOR, and after SOR. Changes in best corrected visual acuity (BCVA), relative risk of severe thinning. It was conducted at Kasr Alainy Hospital.

RESULTS

64 eyes were enrolled in the study. Group A included 36 eyes, and group B included 28 eyes. The mean CFT changed insignificantly from 253 ± 52 μm to 252 ± 48 μm after SOR in group A; while it changed significantly from 211 ± 52 μm to 202 ± 46 μm after SOR in group B. The mean PFT decreased insignificantly from 299 ± 39 μm to 297 ± 40 μm in group A, while it decreased significantly from 284 ± 46 μm to 273 ± 44 μm in group B. Lines of improvement of BCVA were 4.11 ± 1.88 in group A, and 2.00 ± 1.24 in group B. Relative risk of severe foveal thinning after SOR was 14.3, and severe parafoveal thinning was 15.43, in group B compared to group A.

CONCLUSION

Longer period of silicone oil tamponade may carry a higher risk for severe foveal and parafoveal thinning after silicone oil removal.

TRIAL REGISTRATION

The study was registered at clinical trial.gov under the title of (Duration of silicone oil tamponade on foveal and parafoveal thickness in Rhegmatogenous Retinal Detachment) with an ID NCT05817630 at April 2023 "retrospectively registered".

Comparison of the morphological characteristics of the choroidal sublayer between idiopathic macular holes and epiretinal membranes with automatic analysis

PURPOSE

To compare the choroidal sublayer morphologic features between idiopathic macular hole (IMH) and idiopathic epiretinal membrane (iERM) on spectral-domain optical coherent tomography (SD-OCT) using an automatic segmentation model.

METHODS

Thirty-three patients with idiopathic IMHs and 44 with iERMs who underwent vitrectomies were involved. The enhanced depth imaging mode of SD-OCT was used to obtain the B-scan image after single line scanning of the macular fovea. The choroidal sublayer automatic analysis model divides the choroidal into the choroidal large vessel layer, the middle vessel layer and the small vessel layer (LVCL, MVCL and SVCL, respectively) and calculates the choroidal thickness (overall, LVCL, MVCL and SVCL) and vascular index (overall, LVCL, MVCL and SVCL). The morphological characteristics of the choroidal sublayer in the ERM eyes and the IMH eyes were compared.

RESULTS

The mean choroidal thickness in the macular centre of the IMH eyes was significantly thinner than that of the ERM eyes (206.35 ± 81.72 vs. 273.33 ± 82.31 μm; P < 0.001). The analysis of the choroidal sublayer showed that the MVCL and SVCL macular centres and 0.5-1.5 mm of the nasal and temporal macula were significantly thinner in the IMH eyes than in the ERM eyes (P < 0.05), and there was a difference in the macular centre of the LVCL between the two groups (P < 0.05). In contrast, the choroidal vascular index of the macular centre in the IMH eyes was significantly higher than that in iERM eyes (0.2480 ± 0.0536 vs. 0.2120 ± 0.0616; P < 0.05). There was no significant difference in the CVI of other parts of the macula, the LVCL or MVCL between the two groups.

CONCLUSION

The choroidal thickness of the IMH eyes was significantly thinner than that of the iERM eyes, which was mainly observed in 3 mm of the macular centre and the MVCL and SVCL layers of the choroid. The choroidal vascular index of the IMH eyes was higher than that of the iERM eyes. These findings suggest that the choroid may be involved in the pathogenesis of IMH and iERM.

Vitreous Substitutes from Bench to the Operating Room in a Translational Approach: Review and Future Endeavors in Vitreoretinal Surgery

Vitreous substitutes are indispensable tools in vitreoretinal surgery. The two crucial functions of these substitutes are their ability to displace intravitreal fluid from the retinal surface and to allow the retina to adhere to the retinal pigment epithelium. Today, vitreoretinal surgeons can choose among a plethora of vitreous tamponades, and the tamponade of choice might be difficult to determine in the ever-expanding range of possibilities for a favorable outcome. The currently available vitreous substitutes have disadvantages that need to be addressed to improve the surgical outcome achievable today. Herein, the fundamental physical and chemical proprieties of all vitreous substitutes are reported, and their use and clinical applications are described alongside some surgical techniques of intra-operative manipulation. The major upcoming developments in vitreous substitutes are extensively discussed, keeping a translational perspective throughout. Conclusions on future perspectives are derived through an in-depth analysis of what is lacking today in terms of desired outcomes and biomaterials technology.

Association of Aberrant Posterior Vitreous Detachment and Pathologic Tractional Forces With Myopic Macular Degeneration

Purpose

The purpose of this study was to assess whether the tractional elements of pathologic myopia (PM; e.g. myopic traction maculopathy [MTM], posterior staphyloma [PS], and aberrant posterior vitreous detachment [PVD]) are associated with myopic macular degeneration (MMD) independent of age and axial length, among highly myopic (HM) eyes.

Methods

One hundred twenty-nine individuals with 239 HM eyes from the Myopic and Pathologic Eyes in Singapore (MyoPES) cohort underwent ocular biometry, fundus photography, swept-source optical coherence tomography, and ocular B-scan ultrasound. Images were analyzed for PVD grade, and presence of MTM, PS, and MMD. The χ² test was done to determine the difference in prevalence of MMD between eyes with and without PVD, PS, and MTM. Multivariate probit regression analyses were performed to ascertain the relationship between the potential predictors (PVD, PS, and MTM) and outcome variable (MMD), after accounting for possible confounders (e.g. age and axial length). Marginal effects were reported.

Results

Controlling for potential confounders, eyes with MTM have a 29.92 percentage point higher likelihood of having MMD (P = 0.003), and eyes with PS have a 25.72 percentage point higher likelihood of having MMD (P = 0.002). The likelihood of MMD increases by 10.61 percentage points per 1 mm increase in axial length (P < 0.001). Subanalysis revealed that eyes with incomplete PVD have a 22.54 percentage point higher likelihood of having MMD than eyes with early PVD (P = 0.04).

Conclusions

Our study demonstrated an association between tractional (MTM, PS, and persistently incomplete PVD) and degenerative elements of PM independent of age and axial length. These data provide further insights into the pathogenesis of MMD.

Impact of air injection on subretinal fluid following successful scleral buckling surgery for macular-involving retinal detachment

Air injection is an accessory technique during scleral buckling (SB). Subclinical subretinal fluid (SRF) may presence and persistent after SB. The impact of air injection on SRF is unclear. In the study, we retrospectively enrolled 51 patients with macular-involving RD who had undergone successful SB. They were categorized into Group A (SB without air injection) and Group B (SB with air injection). First, we found that although group B seem to be severer than group A before surgery, Kaplan–Meier graph showed that SRF absorbed more rapidly in group B after surgery, and the incidence of SRF in group B was much lower during the whole follow-up period. Moreover, the cases with superior breaks had the lowest incidence. Second, during the follow-up period, there was no significant difference about postoperative complication between two groups. Lastly, risk factors for persistent SRF were investigated with binary logistic regression, and no risk factor was found. In conclusion, air injection during the SB might accelerate SRF absorption and reduce the incidence of persistent SRF, especially for the longstanding macular-off RD with superior breaks.

Study of wetting of the animal retinas by Water and organic liquids and its Implications for ophthalmology

Interfacial properties of the animal retinas are reported. Wetting of the retina-retinal pigment epithelium-choroid-sclera tissues of cow, sheep, and pig eyes by water, silicone and castor oil was explored experimentally. Both water and silicone oils demonstrated complete wetting of the retina, regardless of the viscosity of the silicone oil, whereas the castor oil demonstrated a partial wetting regime. Similar wetting regimes were observed for sheep, cow and pig retinas. The intact surface of animal retina was found to be both hydrophilic and oleophilic. Wetting experiments with double sandwich oil/water layers were performed. Water demonstrated stronger affinity to the retina than silicone and castor oils, and eventually replaced the oils at the liquid/retina interface. We conclude that aqueous solutions continuously secreted in the living eye may displace silicone oil from the retinal surface and contribute to retinal re-detachment. Study of dynamics of wetting of the animal retina by water and organic oils is reported. The exponent describing the dynamics of spreading of the castor oil is lower than that predicted by the Tanner law. Castor oil may provide more effective tamponade than silicone oil.

Comparative assessment of intraocular inflammation following standard or heavy silicone oil tamponade: a prospective study

PURPOSE

To evaluate the inflammation associated with the use of standard silicone oil (polydimethylsiloxane; PDMS) and heavy silicone oil (HSO) Densiron-68™ in patients undergoing vitrectomy for retinal detachment.

MATERIALS AND METHODS

A prospective study was performed involving 35 patients scheduled to undergo vitrectomy for retinal detachment. Patients received PDMS or Densiron-68™ HSO according to superior or inferior retinal localization of the tears, respectively. For assessing the inflammation, prostaglandin E2 (PGE₂ ) and interleukin-1α (IL-1α) levels were evaluated in the aqueous.

RESULTS

Thirty-five eyes of 35 patients completed the study: 20 eyes received HSO, and 15 eyes received PDMS. The mean aqueous PGE₂ level was significantly higher in HSO patients than in PDMS patients (869.16 ± 242.83 pg/ml versus 369.38 ± 209.7 pg/ml, respectively; p < 0.0001). The mean aqueous IL-1α level was also significantly higher in HSO patients than in PDMS patients (81.40 ± 36.9 pg/ml versus 40.8 ± 32.5 pg/ml, respectively; p = 0.002). In HSO, a moderate positive correlation between the endotamponade duration and both PGE₂ (r = 0.44; p = 0.05) and IL-1α (r = 0.48; p = 0.033) levels was observed. In PDMS, a strong positive correlation between the endotamponade duration and both PGE₂ (r = 0.89; p < 0.0001) and IL-1α (r = 0.68; p = 0.006) levels was observed.

CONCLUSION

Although both HSO and PDMS yielded favourable success rates in the surgical treatment of complicated retinal detachments, HSO triggered a more severe inflammatory reaction, in a time-dependent manner.

Macular buckle technique in myopic traction maculopathy: a 16-year review of the literature and a comparison with vitreous surgery

PURPOSE

The aim of this study is to review anatomical and functional outcomes following macular buckling (MB) in high myopia and to compare such results with those obtained by pars plana vitrectomy (PPV).

METHODS

PubMed articles on MB in high myopia (2000-2016) were reviewed. Main outcomes included retinal reattachment and macular hole (MH) closure rates, resolution of myopic foveoschisis (MFS), and postoperative visual acuity.

RESULTS

Thirty-one articles included 16 in patients with retinal detachment due to MH (MHRD group), 11 in MFS with or without foveal detachment (MFS group), and 4 in MH patients with MFS (MH-MFS group). Surgical techniques mainly differed in the type of buckle, rectus muscles involvement, and concurrent PPV. In eyes with persistent MH, prognosis in the MHRD and MH-MFS groups differed between eyes receiving MB compared to PPV: functional outcome was markedly poorer and there was a higher risk of retinal redetachment associated with PPV. In the MSF group, secondary MHs were more likely to develop in eyes treated with PPV and internal limiting membrane peeling than those undergoing MB alone or combined with PPV. Retinal pigment epithelium changes, malpositioning, perforation, and choroidal detachment were the main complications.

CONCLUSIONS

Although different approaches are used, complete resolution of foveoschisis, retinal reattachment, and MH closure seem to be achieved more frequently with MB than PPV.

Retinal Changes Induced by Epiretinal Tangential Forces

Two kinds of forces are active in vitreoretinal traction diseases: tangential and anterior-posterior forces. However, tangential forces are less characterized and classified in literature compared to the anterior-posterior ones. Tangential epiretinal forces are mainly due to anomalous posterior vitreous detachment (PVD), vitreoschisis, vitreopapillary adhesion (VPA), and epiretinal membranes (ERMs). Anomalous PVD plays a key role in the formation of the tangential vectorial forces on the retinal surface as consequence of gel liquefaction (synchysis) without sufficient and fast vitreous dehiscence at the vitreoretinal interface. The anomalous and persistent adherence of the posterior hyaloid to the retina can lead to vitreomacular/vitreopapillary adhesion or to a formation of avascular fibrocellular tissue (ERM) resulting from the proliferation and transdifferentiation of hyalocytes resident in the cortical vitreous remnants after vitreoschisis. The right interpretation of the forces involved in the epiretinal tangential tractions helps in a better definition of diagnosis, progression, prognosis, and surgical outcomes of vitreomacular interfaces.