Hypotony Failure Criteria in Glaucoma Surgical Studies and Their Influence on Surgery Success.

PURPOSE: Review hypotony failure criteria used in glaucoma surgical outcome studies and evaluate their impact on success rates. DESIGN: Systematic literature review and application of hypotony failure criteria to 2 retrospective cohorts. PARTICIPANTS: A total of 934 eyes and 1765 eyes undergoing trabeculectomy and deep sclerectomy (DS) with a median follow-up of 41.4 and 45.4 months, respectively. METHODS: Literature-based hypotony failure criteria were applied to patient cohorts. Intraocular pressure (IOP)-related success was defined as follows: (A) IOP ≤ 21 mmHg with ≥ 20% IOP reduction; (B) IOP ≤ 18 mmHg with ≥ 20% reduction; (C) IOP ≤ 15 mmHg with ≥ 25% reduction; and (D) IOP ≤ 12 mmHg with ≥ 30% reduction. Failure was defined as IOP exceeding these criteria in 2 consecutive visits > 3 months after surgery, loss of light perception, additional IOP-lowering surgery, or hypotony. Cox regression estimated failure risk for different hypotony criteria, using no hypotony as a reference. Analyses were conducted for each criterion and hypotony type (i.e., numerical [IOP threshold], clinical [clinical manifestations], and mixed [combination of numerical or clinical criteria]). MAIN OUTCOME MEASURES: Hazard ratio (HR) for failure risk. RESULTS: Of 2503 studies found, 278 were eligible, with 99 studies (35.6%) lacking hypotony failure criteria. Numerical hypotony was predominant (157 studies [56.5%]). Few studies used clinical hypotony (3 isolated [1.1%]; 19 combined with low IOP [6.8%]). Forty-nine different criteria were found, with IOP < 6 mmHg, IOP < 6 mmHg on ≥ 2 consecutive visits after 3 months, and IOP < 5 mmHg being the most common (41 [14.7%], 38 [13.7%], and 13 [4.7%] studies, respectively). In both cohorts, numerical hypotony posed the highest risk of failure (HR, 1.51-1.21 for criteria A to D; P < 0.001), followed by mixed hypotony (HR, 1.41-1.20 for criteria A to D; P < 0.001), and clinical hypotony (HR, 1.12-1.04; P < 0.001). Failure risk varied greatly with various hypotony definitions, with the HR ranging from 1.02 to 10.79 for trabeculectomy and 1.00 to 8.36 for DS. CONCLUSIONS: Hypotony failure criteria are highly heterogenous in the glaucoma literature, with few studies focusing on clinical manifestations. Numerical hypotony yields higher failure rates than clinical hypotony and can underestimate glaucoma surgery success rates. Standardizing failure criteria with an emphasis on clinically relevant hypotony manifestations is needed. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Ab Interno Ahmed Glaucoma Valve Plugs In An Eye With Persistent Hypotony.

PURPOSE: This case report aims to describe a new method for increasing intraocular pressure (IOP) in patients with acute hypotony resulting from uveitis flare-ups and preexisting glaucoma drainage devices. The temporary glaucoma tube plug method described is effective and safe. METHODS: This case report presents a 47-year-old female patient with a history of chronic panuveitis and secondary glaucoma, who had 2 previously implanted Ahmed glaucoma valves. The patient developed panuveitis flare-up and persistent hypotony. A novel method of ab interno plugging of the glaucoma tubes using 2-0 prolene suture plugs was performed. Following treatment, the IOP increased successfully and remained within the normal range. CONCLUSION: The temporary ab interno glaucoma tube plug method effectively increased IOP in a patient with 2 preimplanted Ahmed glaucoma valves with persistent low IOP due to uveitis.

Morphologic Changes in the Lamina Cribrosa Upon Intraocular Pressure Lowering in Patients With Normal Tension Glaucoma.

Purpose: The purpose of this study was to investigate whether the lamina cribrosa (LC) curve changes in response to intraocular pressure (IOP) reduction following administration of topical ocular hypotensive eye drops in eyes with normal tension glaucoma (NTG). Methods: Ninety-three eyes of 93 patients with treatment naïve NTG at initial examination and with ≥20% reduction from baseline IOP following administration of topical ocular hypotensive eye drops were included. Serial horizontal B-scan images of the optic nerve head (ONH) were obtained from each eye using enhanced depth imaging spectral domain optical coherence tomography (OCT) before and 1 year after IOP-lowering treatment. The LC curvature in each eye was assessed by measuring the LC curvature index (LCCI) in horizontal OCT B-scan images obtained at three (superior, central, and inferior) locations spaced equidistantly across the vertical optic disc diameter before and after IOP-lowering treatment. We evaluated the OCT detectible change in the LC curvature based on the interval change of LCCI to exceed the intersession standard deviation of 1.96 times and factors associated with the magnitude of the LCCI change in the eyes showing significant LC change. Results: IOP decreased from 15.7 ± 2.5 mm Hg at baseline to 11.2 ± 1.7 mm Hg after topical glaucoma medication. Among the 93 subjects, 62 (66.7%) eyes showed the significant reduction of the LCCI (interssetional change over 1.5) after the treatment; greater interssessional change of the LCCI after IOP reduction was associated with younger age (P = 0.020) and larger baseline LCCI (P < 0.001). Conclusions: The OCT detectible changes in LC curvature occurred in response to a modest decrease in the IOP in the naïve NTG eyes. The therapeutic benefit of these changes need to be assessed in longitudinal studies.

Analytical model for managing hypotony after implantation surgery of a glaucoma drainage device.

The main aim of glaucoma treatment is to reduce the intraocular pressure (IOP). One of the most common surgical treatments of glaucoma is the implantation of a glaucoma drainage device to drain the aqueous humor from the anterior chamber to a filtration bleb, where the aqueous humor is absorbed. In some cases, the excess of drainage causes ocular hypotony, which constitutes a sight-threatening complication. To prevent hypotony after this intervention, surgeons frequently introduce a suture into the device tube, which increases the hydraulic resistance of the tube and, therefore, the IOP. This study aims to provide an analytical model to correct hypotony following implantation surgery of a glaucoma drainage device, which may help glaucoma surgeons decide on hypotony treatment. The results indicate that the IOP after implanting a cylindrical tube around 300 µm in diameter is essentially the same as that built up in the filtering bleb and can hardly be controlled by introducing a straight suture unless the suture diameter is slightly lower than that of the tube. On the contrary, when the tube diameter is smaller than, for example, 100 µm, significant reductions of the IOP can be obtained by introducing a thin suture into the tube.

Hypotony Without Globe Rupture During Orbital Fracture Repair.

A 29-year-old male presented to the emergency department with an orbital fracture. He denied ocular symptoms and CT showed bilateral fracture of nasal bones, left medial orbital wall, and left orbital floor, with herniation of orbital fat and minimal retrobulbar hematoma. Pre-operative ophthalmic exam was unremarkable. Intra-operatively, intraocular pressure of the left eye was 5 mm Hg, a significant change from 17 mm Hg preoperatively. Globe exploration revealed no injury. Post-operatively, IOP normalized. With these findings it was felt that ocular manipulation related to the orbital fracture repair placed significant and intermittent pressure on the globe, thereby lowering IOP. Laryngoscope, 131:2238-2240, 2021.

Micropulse transscleral cyclophotocoagulation using a standard protocol in patients with refractory glaucoma naive of cyclodestruction.

PURPOSE: To assess the efficacy and safety of a standardized micropulse transscleral diode laser cyclophotocoagulation procedure in refractory glaucoma. METHODS: Retrospective, interventional study in a series of 37 consecutive patients with refractory glaucoma, cyclodestructive procedure-naive, who underwent micropulse transscleral diode laser cyclophotocoagulation from December 2016 to October 2017. A successful laser treatment was defined as (1) intraocular pressure between 6 and 18 mm Hg; (2) 20% of baseline intraocular pressure reduction; (3) no additional glaucoma medications; (4) no decrease in vision due to complications or change in intraocular pressure; and (5) no need for additional glaucoma surgery except micropulse transscleral diode laser cyclophotocoagulation retreatment. RESULTS: Mean age was 60.2 years. Mean follow-up was 9.7 ± 3.9 months. The mean preoperative intraocular pressure (28.7 mm Hg) significantly decreased to 21.0 mm Hg at 1 month, 18.5 mm Hg at 3 months, 18.4 mm Hg at 6 months, and 18.5 mm Hg at 12 months (p < 0.01 at all time points). The mean number of preoperative glaucoma medications (4.7) decreased to 4.0 at 1 month (p = 0.14), 4.5 at 3 months (p < 0.05), 3.9 at 6 months (p < 0.05), and 3.6 at 12 months (p < 0.05). At 1 year, the success rate was 35% with a mean intraocular pressure lowering of 36%. One patient had hypotony and a loss of best-corrected visual acuity. Mild transient postoperative inflammation was observed in 8% of the cases. CONCLUSION: Using a standardized procedure, micropulse transscleral diode laser cyclophotocoagulation allows a mild intraocular pressure decrease with a low rate of complications and thus achieves a relatively good profit risk benefit, mostly for moderately hypertensive refractory glaucoma.

Optic Disc Edema and Posterior Globe Flattening Secondary to Ocular Hypotony: Case Report and Discussion Regarding Pathophysiology and Clinical Findings.

ABSTRACT: We describe a case of a young female patient presenting with ocular hypotension (4 mm Hg) secondary to cyclodialysis, and optic disc edema (ODE) after a blunt trauma in the right eye (right eye). MRI showed posterior globe flattening of the right eye, drawing our attention to the pathophysiology behind these findings. The combination of ODE and posterior globe flattening, as observed in the present case of ocular hypotony, is known from other conditions such as intracranial hypertension and space-flight neuro-ocular syndrome, pointing to a common pathophysiological mechanism, possibly resulting from axoplasmic stasis at the level of the lamina cribrosa due to a high translaminar pressure difference.

Loss of Pressure Control Resulting from Tube Bending during Glaucoma Drainage Tube Perforations.

PURPOSE: Tube perforations are a common method of achieving early intraocular pressure control with ligated glaucoma drainage devices (GDDs). Our purpose was to investigate how bending GDD tubes affects the performance of needle perforations. DESIGN: Experimental report. PARTICIPANTS: Twenty silicone GDD tubes attached to 27 G Rycroft cannulae tied with 7-0 Vicryl 10 mm from the cannulae tips. METHODS: Silicone GDD tubing was fitted over a 27 G Rycroft cannula and tied with a 7-0 suture 10 mm from the cannula tip. The tube was perforated 4 mm from the cannula tip with a 25 G needle (tube was kept straight). The tube was secured in a 50-mm water bath. Aqueous food dye was infused through the cannula from an adjustable height. The tube was observed under magnification while the height of the fluid column was adjusted to establish the pressure gradient at which the tube leaked dye (opening pressure) and ceased to leak (closing pressure), while the tube was held straight and bent 90 degrees. Measurements were repeated after a second perforation and a third perforation. Ten tubes were tested this way with 3 sequential slits. The entire experiment was repeated with another 10 tubes, but this time the tube was allowed to bend within the 3.5-mm open prongs of a needle holder during needle perforation. MAIN OUTCOME MEASURES: Opening and closing pressures. RESULTS: For each tube, the opening and closing pressures were similar and highly reproducible, but there was wide variation between tubes. In the tubes kept straight when perforated, the opening/closing pressure ranged from 5 to 25 cmH2O. The opening and closing pressures of slits made in the bent tube were significantly lower, frequently leaking at <1 cmH2O. Bending the tube after perforation could close a slit and prevent leakage at high perfusion pressure. The second and third successive perforations caused lower opening and closing pressures. CONCLUSIONS: Tube perforations behave like pressure-sensitive valves, opening whenever intraluminal pressure increases above a specific value. However, we found a large variation in the performance of fenestrations made with a 25-G hypodermic needle. Allowing the GDD tube to bend during needle perforation increases the risk of very low opening and closing pressures.

Association Between Structure-function Characteristics and Visual Field Outcomes in Glaucoma Subjects With Intraocular Pressure Reduction After Trabeculectomy.

PRECIS: Improvements in post-trabeculectomy visual field (VF) outcomes were found to be significantly associated with preoperative nerve fiber layer thickness parameters extracted from the sectorized structure-function relationship, baseline VF, and severity of glaucoma. OBJECTIVE: To determine whether the preoperative structure-function relationship helps to predict visual outcomes at 1-year post-trabeculectomy. PATIENTS AND METHODS: In total, 91 eyes from 87 participants who successfully underwent trabeculectomy were included in our study. All eyes received optical coherence tomography imaging and VF assessment using 30-2 standard automated perimetry preoperatively at baseline and postoperatively 1 year after trabeculectomy. The linear mixed-model analysis was used to assess the association of structure and function at baseline, and multivariate analysis to investigate factors associated with postoperative VF outcomes. RESULTS: Results from multivariate and univariate analysis for VF 1 year after trabeculectomy showed that a positive preoperative retinal nerve fiber layer thickness deviation from the structure-function model was found to be significantly associated with improved postoperative VF outcomes [ß=0.06 dB/µm; 95% confidence interval (CI), 0.03-0.09]. Other significant factors included baseline VF MD (ß=-0.18; 95% CI, -0.23 to -0.13) and the presence of severe glaucoma (ß=-1.69; 95% CI, -2.80 to -0.57). Intraocular pressure was positively associated with improved VF outcomes only in univariate analysis (ß=0.06; 95% CI, 0.01-0.11). CONCLUSIONS AND RELEVANCE: Characteristics derived from the baseline structure-function relationship were found to be strongly associated with postoperative VF outcomes. These findings suggest that the structure-function relationship could potentially have a role in predicting VF progression after trabeculectomy.

Management of Ocular Hypotony After Tube Surgery Using Bent Intraluminal Stents.

PURPOSE: We aimed to report a surgical technique for the management of ocular hypotony after tube surgery. METHODS: We occluded the tube with ab interno insertion of 2 bent 5-0 polypropylene threads into the tube lumen. Bent stents were used to prevent stent displacement. RESULTS: Our case series revealed that this procedure effectively resolved hypotony. Among the 3 cases, the stents were removed in 1 case and left in place in 2 cases. In all cases, the stent location remained stable without displacement. CONCLUSION: The insertion of bent intraluminal stents into the tube may be a useful method for the management of ocular hypotony after tube surgery.

Intraocular Pressure Reduction After Real-world Cataract Surgery.

PRéCIS:: A large cohort undergoing cataract extraction was retrospectively analyzed to ascertain the degree of real-world intraocular pressure (IOP) reduction in normal eyes and those with glaucoma, and a predictive formula was developed. PURPOSE: The purpose of this study was to define the real-world degree of IOP reduction after cataract extraction to guide its role as an isolated intervention for glaucoma. MATERIALS AND METHODS: A retrospective analysis was carried out of clinical data collected in 8 clinical sites in the United Kingdom from an electronic medical record system between January 2006 and May 2015. A total of 20,508 eyes without known pathology and 2251 eyes from patients with glaucoma undergoing phacoemulsification and intraocular lens insertion were included. Eyes with intraoperative complications, undergoing additional procedures, axial lengths outside 22 to 26.5 mm, preoperative IOP under 6 mm Hg or over 30 mm Hg, and copathology, except for amblyopia or glaucoma, were excluded. The main outcome measure was the change in preoperative IOP compared with the next recorded visit for up to 12 weeks. RESULTS: In eyes without pathology, the mean reduction in IOP was 1.40 mm Hg (±3.74) compared with 1.03 (±5.02), P-value <0.001, in eyes with a diagnosis of glaucoma. A multiple linear regression model identified preoperative IOP, a glaucoma diagnosis, preoperative corrected visual acuity, age, and axial length as determinants of IOP reduction. The model was validated against an independent cohort. CONCLUSIONS: We quantify mean IOP reduction achieved in a real-world setting from cataract surgery alone. In glaucomatous eyes where angle closure is not differentiated, phacoemulsification alone yields only a modest reduction of IOP.

Intraocular Pressure After Cataract Surgery Combined With Ab Interno Trabeculectomy Versus Trabecular Micro-bypass Stent: An Intrasubject Same-surgeon Comparison.

PRECIS: Combining Trabectome or iStent with phacoemulsification equally reduces intraocular pressure (IOP) and IOP-lowering medication burden during a 24-month follow-up, with a possible advantage to the Trabectome in the early postoperative period. PURPOSE: Intrasubject same-surgeon comparison between phacoemulsification combined with Trabectome (Phaco/Trabectome) versus one first-generation iStent (Phaco/iStent). SETTINGS: Private glaucoma and cataract practice. DESIGN: This is a retrospective interventional case series. METHODS: Data collected at 3 to 4 and 20 to 24 hours and up to 30 months following Phaco/Trabectome in 1 eye and Phaco/iStent in the contralateral eye in patients with bilateral visually-significant cataract and open-angle glaucoma. Evaluations included IOP, intraocular pressure-lowering medications (IOPmeds), visual acuity, and complications. RESULTS: Forty-five patients (90 eyes) were identified (age 76.5, 57 to 95 y). At 3 to 4 hours, IOP was above baseline in 12 and 13 eyes following Phaco/Trabectome and Phaco/iStent, respectively, but the degree of IOP elevation was smaller (P=0.048) following Phaco/Trabectome: 4.3 mm Hg, 2.0 to 6.6 mm Hg (95% confidence interval) versus Phaco/iStent: 8.7 mm Hg, 3.8 to 13.6 mm Hg. At 20 to 24 hours, compared with baseline, IOP was significantly lower after Phaco/Trabectome (P=0.004) but not after Phaco/iStent (P=0.14) although the rate of hyphema was higher following Phaco/Trabectome (12/45 vs. 2/45 eyes, P=0.007). IOP reduction from baseline at 3 to 4 hours was significantly larger (P=0.020) in the 21 eyes with hyphema: -3.9, -6.4 to -1.4 versus the 69 eyes without hyphema: -0.3, -2.0 to +1.4. At 1, 6, 12, and 24 months, IOP and number of IOPmeds were similar and significantly lower compared with baseline following either procedure. No complications were encountered in either group. CONCLUSIONS: Combined phacoemulsification with either Trabectome or first-generation iStent similarly lowers IOP and IOPmeds burden at 1, 6, 12, and 24 months following surgery. The Trabectome may have an advantage in lowering IOP faster and lessening the degree of IOP elevations in the early postoperative period.

MP3 Plus: A Modified Micropulse Transscleral Cyclophototherapy Technique for the Treatment of Refractory Glaucoma.

PRéCIS:: In advanced refractory glaucoma which has failed prior MP3 laser, MP3 Plus is effective in reducing intraocular pressure (IOP) without significant complications. It is also useful as a temporizing procedure before incisional surgery. PURPOSE: To evaluate the efficacy and safety of MP3 Plus, a novel technique using modified micropulse transscleral cyclophototherapy (MPTCP) in eyes with refractory glaucoma or failed MPTCP treatment. METHODS: This is a retrospective interventional case series. In total, 32 consecutive eyes from 29 patients with uncontrolled IOPs who had previous MPTCP or refractory glaucoma underwent MP3 Plus, a modified MPTCP where additional discrete pulses are applied. The main outcome measurement was IOP at 1, 3, 6, and 12 months postprocedure, with success defined as a 20% reduction in baseline IOP, an IOP of 25 mmHg or less, and no need for further reoperation. We collected and analyzed visual acuity, number of glaucoma medications, and complications. RESULTS: The patients had an average of 1.4±0.9 glaucoma procedures before treatment, where 87.5% underwent one or more previous MPTCP with suboptimal response. Of the eyes presenting for follow-up, 51.6% (n=31), 37.0% (n=27), 35.7% (n=28), and 25.9% (n=27) achieved the primary outcome at 1, 3, 6, and 12 months, respectively. Baseline IOP was 33.7±11.6 mmHg (n=32 eyes) and posttreatment IOP at 1, 3, 6, and 12 months were 21.0±9.0 mmHg (n=31; P<0.0001), 26.2±10.8 mmHg (n=25; P<0.0001), 23.2±9.4 mmHg (n=20; P<0.05), and 24.6±9.8 mmHg (n=16; P<0.001), respectively. There was a reduction in glaucoma medications from 3.4±0.8 preoperatively to 2.8±1.2 (n=16; P<0.05) at 12 months. There were no cases of prolonged inflammation or hypotony. CONCLUSIONS: MP3 Plus is effective and safe in lowering IOP in eyes with refractory glaucoma after previous failed MPTCP.

Rate of hypotony and intraocular pressure fluctuation immediately after intravitreal dexamethasone implantation in vitrectomized eyes.

PURPOSE: To observe the rate of hypotony and intraocular pressure (IOP) fluctuations immediately following intravitreal dexamethasone implantation in vitrectomized eyes. METHODS: The study included previously vitrectomized eyes scheduled to receive intravitreal dexamethasone implants. IOP measurements were performed at minute 1, minute 10, hour 1, hour 2, hour 3 and day 1. The primary outcome measure of the study was the rate of hypotony at the various time points, while the secondary outcome measure was the IOP profile over time. RESULTS: A total of 26 eyes were enrolled in the study. Immediately following the injection, 11 (42.3%) of the eyes exhibited an IOP<6mm Hg. Hypotony was observed in one eye (3.8%) at hour 3 and day 1. After the immediate IOP reduction, IOP recovered rapidly and showed a peak at hour 1, with 5 eyes (19.2%) exhibiting IOP levels ≥25mmHg and 1 eye (3.8%) ≥30mm Hg. Aside from the eye with persistent hypotony resulting in a choroidal effusion, no other complication was observed. CONCLUSIONS: Injection of dexamethasone implants in vitrectomized eyes resulted in immediate IOP reduction. Hypotony showed a short, self-limited course in the majority of eyes. In the presence of additional risk factors for wound incompetency, regular follow-up in the early post-injection period appears to be needed.

Conjunctival bleb compression as a treatment for hypotony post XEN45 implant in uveitic glaucoma.

PURPOSE: Over-filtration and subsequent hypotony are recognised complications of penetrating glaucoma procedures, especially when augmented with antimetabolites. Patients with uveitis are especially at risk of hypotony and this can reduce the final acuity achieved, compromise surgical outcomes and adversely affect the inflammatory status. The incidence of hypotony following XEN45 implant insertion is higher for uveitic patients and we present a method of surgically addressing this hypotony with transconjunctival compression sutures that are placed over the overdraining XEN45 implant. METHODS: We present a retrospective case series of consecutive uveitic glaucoma patients who had conjunctival compression sutures between 2015 and 2018 following XEN45 insertion, at the Manchester Royal Eye Hospital, UK. Two 9/0 nylon sutures were placed in a horizontal figure-of-eight conformation transconjunctivally across the overdraining bleb: one directly over the XEN45 implant and one at the posterior limit of the implant in order to restrict flow. RESULTS: Three patients underwent conjunctival compression sutures following XEN45 implant-related hypotony and all three had successful resolution of their hypotony and visual symptoms. No patients required long-term topical agents to control their intraocular pressure. CONCLUSION: Conjunctival compression sutures are an effective option for addressing persistent hypotony following XEN45 implant insertion in patients with uveitic glaucoma.

Cauterized suture for complete tube occlusion of Ahmed glaucoma valve in hypotony maculopathy.

PURPOSE: To present our experience treating hypotony maculopathy with a simple, minimally invasive, and removable ab interno tube Ahmed glaucoma valve occlusion. METHODS: Under topical anesthesia a 5-0 polypropylene suture (Prolene; Ethicon) was inserted into the Ahmed glaucoma valve tube. The length of the tube was measured, and an external suture cauterization was performed to allow an easier and safer fixation in the tube. The suture was introduced into the tube itself with the viscoelastic 27-gauge cannula. RESULTS: This technique was performed in three cases of hypotony maculopathy with a complex history of medical treatments: a 4-year-old boy with Donnai-Barrow syndrome and previous pars plana vitrectomy that developed hypotony maculopathy the day after Ahmed glaucoma valve insertion and two male patients (69 and 49 years old) that underwent hypotony maculopathy after cyclophotocoagulation as a last option to reduce intraocular pressure. One of the men had three filtering surgeries, two 5-fluorouracil needlings and Ahmed glaucoma valve insertion. The other male patient had keratoplasty and posterior Ahmed glaucoma valve insertion. In the three cases, both hypotony and maculopathy were reversed within a week and a month, respectively, after Ahmed glaucoma valve occlusion with no complications. When hypotony maculopathy develops it seems suitable to occlude completely the Ahmed glaucoma valve tube to swiftly reverse clinical and anatomic changes. CONCLUSION: Intraluminal Ahmed glaucoma valve occlusion with cauterized suture is a simple, quick, reversible, and effective technique that may offer a minimally invasive way to resolve hypotony maculopathy in complex cases and avoid severe loss of vision.

INCIDENCE AND RISK FACTORS FOR HYPOTONY AFTER 25-GAUGE PARS PLANA VITRECTOMY WITH NONEXPANSILE ENDOTAMPONADE.

PURPOSE: The purpose of this study was to assess the incidence and risk factors for early postoperative hypotony after 25-gauge pars plana vitrectomy with nonexpansile endotamponade. METHODS: A retrospective study of consecutive patients who underwent 25-G pars plana vitrectomy. Hypotony was defined as an intraocular pressure of 5 mmHg or less after surgery and ocular hypertension as an intraocular pressure greater than 21 mmHg. RESULTS: Overall, 307 eyes of 307 patients with a mean age of 61.7 ± 14.3 of which 56.7% were males were included. Hypotony was identified in 5.2% of cases (n = 16) at Day 1 and 0.7% (n = 2) at Week 1 with no hypotony-related complications. The hypotony group had a higher number of previous vitreoretinal surgeries (1.5 ± 1.1 vs. 0.4 ± 0.7, P < 0.001) and a higher prevalence of preoperative ocular hypertension (22.2% vs. 4.8%, P = 0.02), pseudophakia (77.8% vs. 48.4%, P = 0.01), silicone oil removal (61.1% vs. 8.3%, P < 0.001), and external diathermy performed (55.6% vs. 20.1%, P = 0.001). In stepwise multivariate analysis, significant parameters were silicone oil removal (R = 16.34%, odds ratio 13.45, P < 0.001), pseudophakia (R = 5.69%, odds ratio 3.65, P = 0.03), and younger age (R = 2.68%, odds ratio 0.96, P = 0.04). CONCLUSION: Silicone oil removal is a significant risk factor for early postoperative hypotony after 25-G pars plana vitrectomy.