Long-Term Changes in Intraocular Pressure after Vitrectomy for Rhegmatogenous Retinal Detachment, Epi-Retinal Membrane, or Macular Hole

Changes of aqueous humor cytokine profiles of patients with high intraocular pressure after PPV for retinal detachment

High intraocular pressure (IOP) is one of the early complications after pars plana vitrectomy (PPV), which may cause glaucoma and poor visual prognosis secondary to surgery. Proliferative vitreoretinopathy (PVR) is one of the complications of retinal detachment (RD) and is the main reason for the poor prognosis, which is related to different kinds of cytokines. It's essential for the basic mechanism to analyze the relative aqueous humor cytokine profiles with IOP after PPV for RD. In this study, we have collected the aqueous humor of 16 patients and qualified 27 cytokines using Luminex and compared biomarkers with the high IOP group and the normal group. As a result, the concentrations of VEGF, IL-6, FGF2, and G-CSF upregulated significantly (P < 0.05), while VEGFR2 downregulated significantly (P < 0.05) in the high IOP group. IL-6 was positively correlated with high IOP (r = 0.561, P = 0.041). Meanwhile, the concentrations of IL-6 (r = 0.543, P = 0.03), IL-5 (r = 0.576, P = 0.019), IL-15 (r = 0.614, P = 0.011), IL-4 (r = 0.517, P = 0.04), ICAM-1 (r = 0.611, P = 0.012), and G-CSF (r = 0.636, P = 0.008) were significantly associated with preoperative PVR classification, and the aqueous humor levels of IL-4 (r = 0.567, P = 0.022), HGF (r = 0.701, P = 0.005), and MCP-1 (r = 0.565, P = 0.035) are significant relative to laser points. Hence, cytokines might potentially be the therapeutic target of high IOP after PPV.

Changes in Intraocular Pressure and Anterior Chamber Parameters Following Cataract Surgery, Vitrectomy, and Combined Surgery

PURPOSE

The aim of this study is to investigate changes in intraocular pressure (IOP) and anterior-segment parameters before and after cataract surgery, vitrectomy, and combined surgery.

METHODS

The records of patients who had undergone cataract surgery (cataract group), vitrectomy (vitrectomy group), or combined cataract surgery and vitrectomy (combined group) at our hospital were retrospectively examined. The vitrectomy group consisted of pseudophakic eyes. IOP and anterior-segment measurements, including anterior chamber depth (ACD), angle opening distance (AOD), trabecular-iris angle (TIA), and trabecular-iris space area (TISA), were measured using swept-source anterior-segment optical coherence tomography before and 6 months after surgery in 41, 15, and 40 eyes, respectively.

RESULTS

In the cataract and combined groups, there was a decrease in IOP (cataract group: from 15.8 to 13.4 mmHg, p <0.001; combined group: from 15.8 to 14.2 mmHg, p = 0.002) and an increase in the central corneal thickness after surgery (p <0.001). The ACD increased in all groups, with a smaller increase in the vitrectomy group (p <0.03). Postoperative AOD, TIA, and TISA were significantly increased in the cataract and combined groups (p <0.02). Higher preoperative IOP and larger IOP reduction after surgery were correlated with smaller preoperative AOD, TISA, and TIA in cataract and combined groups (p <0.034). A small preoperative ACD was related to smaller preoperative AOD, TISA, TIA (r > 0.649, p <0.001), and postoperative IOP reduction in the cataract and combined groups (r = 0.377, p = 0.018 and r = 0.559, p = 0.001, respectively).

CONCLUSIONS

Compared to the vitrectomy group, the cataract and combined groups showed reduced postoperative IOP and increased AOD, TISA, and TIA. In these two groups, patients with shallower preoperative ACDs showed greater changes in IOP after surgery. Changes in IOP after surgery are thought to be related to changes in the anterior segment caused by the removal of the crystalline lens.

Prediction model for elevated intraocular pressure risk after silicone oil filling based on clinical features

Background

To evaluate risk factors and further develop prediction models for intraocular pressure elevation (IOP) after vitreoretinal surgery with silicone oil tamponade to support clinical management.

Methods

A retrospective study analyzed 1,061 eyes of 1,061 consecutive patients that presented to the Jiangsu Province Hospital between December 2015 and December 2020, the IOP was measured from the preoperative visit and at the 1-week, 1-month, 3-month, and 6-month visits, and the final postoperative visit before silicone oil removal. Four machine learning methods were used to carried out the prediction of IOP elevation: Decision Tree, Logistic Regression, Random Forest, and Gradient-Boosted Decision Trees (GBDT) based on features including demographic and clinical characteristics, preoperative factors and surgical factors. Predictors were selected based on the p-value of the univariate analysis.

Results

Elevated intraocular pressure developed in 26.01% of the eyes postoperatively. Elevated intraocular pressure primarily occurred within 1-2 weeks after surgery. Additionally, the majority of IOP values were distributed around 25-40 mmHg. GBDT utilizing features with p-values less than 0.5 from the hypothesis testing demonstrated the best predictive performance for 0.7944 in accuracy. The analysis revealed that age, sex, hypertension, diabetes, myopia, retinal detachment, lens status and biological parameters have predictive value.

Conclusion

Age, sex, hypertension, diabetes, myopia, retinal detachment, lens status and biological parameters have influence on postoperative intraocular pressure elevation for patients with silicone oil tamponade after pars plana vitrectomy. The prediction model showed promising accuracy for the occurrence of IOP elevation. This may have some reference significance for reducing the incidence of high intraocular pressure after pars plana vitrectomy combined with silicone oil filling.

Assessment of the Effectiveness of Glaucoma Treatment Using MicroPulse Transscleral Cyclophotocoagulation in Patients with Glaucoma Who Have Previously Undergone Vitreoretinal Surgery

INTRODUCTION

This retrospective study aimed to assess the effectiveness of using MicroPulse transscleral cyclophotocoagulation (µP-TSCPC) in patients who had previously undergone pars plana vitrectomy (PPV), depending on the endotamponade used.

METHODS

For the study, a total of 60 patients were enrolled who underwent PPV followed by tμP-TSCPC as a result of an increase in intraocular pressure (IOP) over the norm of 21 mmHg. In this group of patients, 20 received silicone oil endotamponade during PPV, 20 received sulfur hexafluoride gas SF6, and in another 20 a differentiated balanced salt solution (BSS) was used.

RESULTS

The main indications for conducting PPV were (1) retinal detachment (silicone oil endotamponade was used; n = 12); (2) dislocation/subluxation of the patient's own or artificial intraocular lens (balanced salt solution (BSS) endotamponade was used; n = 11); (3) the presence of an epiretinal membrane and/or a macular hole (BSS endotamponade was used; n = 9, or SF6; n = 20); and (4) hemorrhage into the vitreous chamber (silicone oil endotamponade was used; n = 8).

CONCLUSION

The choice of endotamponade used during PPV was not found to determine the effectiveness of µP-TSCPC treatment. The effectiveness of µP-TSCPC in patients after PPV depended, above all, on the etiology of the disease, for which PPV was previously performed. The lowest effectiveness of µP-TSCPC was noted in cases where the reason for conducting PPV was hemorrhage into the vitreous chamber and silicone oil endotamponade was used, while the highest effectiveness was noted in cases where PPV was conducted owing to the presence of an epiretinal membrane and/or a macular hole and SF6 endotamponade was used.

Mendelian randomization analyses in ocular disease: a powerful approach to causal inference with human genetic data

Ophthalmic epidemiology is concerned with the prevalence, distribution and other factors relating to human eye disease. While observational studies cannot avoid confounding factors from interventions, human eye composition and structure are unique, thus, eye disease pathogenesis, which greatly impairs quality of life and visual health, remains to be fully explored. Notwithstanding, inheritance has had a vital role in ophthalmic disease. Mendelian randomization (MR) is an emerging method that uses genetic variations as instrumental variables (IVs) to avoid confounders and reverse causality issues; it reveals causal relationships between exposure and a range of eyes disorders. Thus far, many MR studies have identified potentially causal associations between lifestyles or biological exposures and eye diseases, thus providing opportunities for further mechanistic research, and interventional development. However, MR results/data must be interpreted based on comprehensive evidence, whereas MR applications in ophthalmic epidemiology have some limitations worth exploring. Here, we review key principles, assumptions and MR methods, summarise contemporary evidence from MR studies on eye disease and provide new ideas uncovering aetiology in ophthalmology.

Case Report: Microincision Vitreous Surgery Induces Bleb Failure in Eyes With Functional Filtering Bleb

Purpose

To investigate the effect of microincision vitreous surgery (MIVS) on intraocular pressure (IOP) control in glaucomatous eyes with functional filtering bleb.

Methods

We enrolled 18 patients (15 males; median age, 73 years) who previously had filtering surgery and underwent MIVS with functional filtering bleb. Kaplan–Meier method was used to calculate the survival rate with defined the failure as when more number of preoperative antiglaucoma medication was started or additional glaucoma surgery including bleb revisions were performed, and IOP increase of 20% (criteria 1) and 30% (criteria 2) from preoperative levels after 2 weeks of MIVS.

Results

The median follow-up duration was 970 days. Preoperative IOP was 13.3 ± 3.8 mmHg (mean ± SD). Postoperative IOP were 14.7 ± 4.9 (P=0.365), 15.2 ± 3.5 (P=0.137), 16.4 ± 5.6 (P = 0.073), 17.6 ± 6.1(P = 0.020), and 14.5 ± 4.0 (P = 0.402) mmHg at 3, 6, 12, and 15 months and final visit, respectively (compared to preoperative IOP). The number of antiglaucoma medications was a median of 1.0 (range 0–4) preoperatively and 0 (0–4) at the final visit (P = 0.238). The survival rates were 55%/61% at 3 months, 50%/61% at 6 months, and 38%/55% at 12 months with criteria 1 and 2, respectively. Four eyes (22%) received additional glaucoma surgery during follow-up.

Conclusion

After several months of MIVS, IOP was likely to increase. We should focus on IOP control by conducting long-term follow-ups.

Long-Term Intraocular Pressure Changes after Pars Plana Vitrectomy: An 8-Year Study

Purpose:

To investigate the long-term changes of intraocular pressure (IOP) after pars plana vitrectomy (PPV).

Methods:

This was a retrospective historical cohort study. Patients with a history of vitrectomy in one eye by a single surgeon were enrolled. IOP of the operated eye was compared to the fellow eye. Previous scleral buckling, IOP rise due to surgical/anatomic complications, silicone oil (SO) emulsification, and contralateral ocular hypertension/glaucoma at recruitment were exclusion criteria. “Significant IOP rise” (>6.0 mmHg) and development of open angle glaucoma (OAG) were the main outcome measures.

Results:

Two hundred and twenty-five eyes were included. Mean and median follow-up duration were 20.6 and 9.0 months, respectively. Mean baseline IOP and mean final IOP were 13.53 ± 3.75 mmHg and 16.52 ± 6.95 mmHg, respectively (P < 0.001). Forty-three patients developed “significant IOP rise” with no statistically significant relation to the indication of vitrectomy, the postoperative lens status, and number of vitrectomies (P = 0.410, P = 0.900, and P = 0.160, respectively). SO injection raised the probability of IOP rise in the long-term (P = 0.028). OAG occurred in 17 patients (7.5%) with no association to SO tamponade (P = 0.840). “Significant IOP rise” and OAG occurred in 3 and 1 control eyes, respectively, significantly lower than the rates in study eyes (P < 0.001).

Conclusion:

Mean IOP slightly rose in the long-term after PPV. SO tamponade was associated with IOP rise in the long-term but not with the incidence of OAG. Both IOP rise and OAG were more probable after vitrectomy.

Association of Myopia and Intraocular Pressure With Retinal Detachment in European Descent Participants of the UK Biobank Cohort: A Mendelian Randomization Study

Importance

Rhegmatogenous retinal detachment is a potentially sight-threatening condition. The role of myopia or intraocular pressure (IOP) in retinal detachment remains unclear.

Objective

To determine if myopia or IOP is associated with retinal detachment risk using genetic data.

Design, Setting, and Participants

Observational analyses and 2-sample mendelian randomization were used to evaluate the associations between myopia, IOP, and retinal detachment risk in European descent participants from the UK Biobank (UKBB) cohort (n = 405 692). For retinal detachment, a genome-wide association study on 4257 cases and 39 181 controls in the UKBB was conducted. Genetic variants associated with mean spherical equivalent (MSE) refractive error (n = 95 827) and IOP (n = 101 939) were derived using independent participants from the retinal detachment genome-wide association study. Recruitment to the UKBB occurred between 2006 and 2010, and data analysis occurred from February 2019 to March 2020.

Main Outcomes and Measures

The odds ratio (OR) of retinal detachment caused by per-unit increases in MSE refractive error (in diopters [D]) and IOP (in mm Hg).

Results

Of the 405 692 participants in the UKBB cohort, the mean (SD) age was 56.87 (7.96) years, the mean (SD) MSE was -0.31 (2.65) D, the mean (SD) corneal-compensated IOP was 16.05 (3.49) mm Hg, and 4253 participants (1.0%) had retinal detachment. Genetic analyses of the 4257 cases and 39 181 controls identified 2 novel retinal detachment genes: COL22A1 (lead single-nucleotide variant rs11992725; P = 4.8 × 10-10) and FAT3 (lead single-nucleotide variant rs10765568; P = 1.2 × 10-15). Genetically assessed MSE refractive error was negatively associated with retinal detachment (per-unit [D] increase in MSE refractive error: OR, 0.72; 95% CI, 0.69-0.76; P = 3.8 × 10-44). For each 6-D decrease in MSE refractive error (representing the move of refractive error from emmetropia to high myopia), retinal detachment risk increased 7.2-fold (95% CI, 5.19-9.27). For per-unit (mm Hg) genetically assessed increase in IOP, the risk of retinal detachment increased by 8% (OR, 1.08; 95% CI, 1.03-1.14; P = .001).

Conclusions and Relevance

This study provides genetic support for the assertion that myopia and IOP are associated with the risk of retinal detachment and that myopia prevention efforts may help prevent retinal detachment.

Pars Plana Vitrectomy and the Risk of Ocular Hypertension and Glaucoma: Where Are We?

Purpose is to review the pathogenic mechanism for ocular hypertension and glaucoma development after pars plana vitrectomy. Both acute and chronic causes are considered, and special attention is paid to the theories and clinical evidence on the risk of developing Open Angle Glaucoma (OAG) after Pars Plana Vitrectomy (PPV). Most existing scientific literature on the issue agree on the role of ascorbate as an oxygen scavenger within the vitreous chamber. Oxygen tension in the vitreous and anterior chamber is maximum inn proximity of the retinal surface and endothelium, respectively and steeply decreases toward the lens, on both sides, and trabecular meshwork. Vitreous removal and, to a lesser extent, liquefaction, greatly reduces oxygen tension gradient in vitreous chamber while cataract extraction has similar effects on anterior chamber oxygen gradients. Oxygen derivatives originated from the cornea and retina are actively reduced by the vitreous gel and/or the crystalline lens. Vitreous removal and cataract extraction reduce drastically this function. Most reported clinical series confirm this hypothesis although protocol difference and follow-up length greatly impact the reliability of results.

Influence of pars plana vitrectomy for macular surgery on the medium term intraocular pressure

Purpose

To evaluate the long-term effect of 20 and 23 gauge pars plana vitrectomy (PPV) on intraocular pressure (IOP).

Methods

Study type: Monocentric retrospective cohort study. 249 eyes of 249 patients undergoing PPV due to epiretinal membrane (EM), idiopathic macular hole (IMH) or vitreoretinal traction (VT) were included. The fellow eye served as control. Exclusion criteria were factors known to influence the IOP, such as cataract surgery during follow-up, extended use of steroids, cryotherapy and silicone oil endotamponade. The relative change of IOP (operated vs. fellow eye) at 6–12 months after surgery was defined as primary endpoint. Secondary endpoints were the relative change of IOP at 3–6 and 12–24 months. Possible influencing cofactors were analysed using ANCOVA.

Results

The primary endpoint did not show a significant IOP reduction of the operated eye relative to the fellow eye (P = 0.089, n = 84). However, the IOP of the operated eye alone was significantly reduced at 6–12 and 12–24 months after surgery (-0.75 ± 2.80 and -1.22 ± 3.29 mmHg, P = 0.008 and 0.007, respectively). The IOP of the fellow eye was also significantly reduced at the 12–24 months period (-0.75 ± 2.73 mmHg, P = 0.008). In the subgroup analysis, sclerotomy size was a significant influencing cofactor, leading to lower IOP after 20G compared to 23G vitrectomy (P = 0.04).

Conclusion

Pars plana vitrectomy did not induce a significant long-term IOP reduction relative to the contralateral eye. However, we observed a IOP lowering potential in 20G vitrectomy.

Comparison of Methods of Endotamponade Used During 23-Gauge Pars Plana Vitrectomy and the Risk of Raised Intraocular Pressure During 24-Month Follow-Up: A Retrospective Study of 196 Patients

BACKGROUND Pars plana vitrectomy (PPV) is used to treat retinal conditions, including retinal detachment, and involves removal of the vitreous gel from the eye. Complications following PPV include raised intraocular pressure (IOP). This retrospective study aimed to compare methods of endotamponade used during 23-gauge PPV and the risk of raised IOP during 24-month follow-up at a single center. MATERIAL AND METHODS The study included 196 patients (age, 15-86 years; mean, 63.5 years) (196 eyeballs). There were 93 patients (47.45%) with a preoperative history of type 2 diabetes mellitus and 14 patients (7.14%) with a history of myopia. IOP was measured with Goldmann applanation tonometry at one-, three-, six-, 12-, and 24-month follow-up. The outcome was compared following endotamponade with silicone oil, sulfur hexafluoride (SF6), and balanced salt solution (BSS). RESULTS Mean IOP at one-month follow-up was 17.2 mmHg (±3.61 mmHg; range, 9-45 mmHg), and at 24-month follow-up was 17.3 mmHg (±3.23 mmHg; range, 7-30 mmHg). IOP following PPV was significantly associated with the indication for PPV (P=0.023), and the type of endotamponade used (P=0.049). In patients with silicone oil endotamponade, the risk of IOP at 24 months was increased by 2.3 times compared with SF6 or BSS endotamponade. Patients with SF6 endotamponade had a risk of IOP that was 3.3 times lower than for silicone oil tamponade or BSS tamponade. CONCLUSIONS Silicone oil endotamponade in PPV was associated with an increased risk of IOP at 24-month follow-up.

Positional Intraocular Pressure of Vitrectomized and Normal Fellow Eyes

Purpose

To compare posture-induced intraocular pressure (IOP) changes in vitrectomized eyes and normal eyes of patients who had vitrectomy in one eye.

Methods

A total of 31 patients older than 20 years of age who underwent vitrectomy were enrolled in the study. At least six months after vitrectomy, we measured IOP in both eyes using a rebound tonometer 10 minutes after the patient assumed sitting, supine, right lateral decubitus, and left lateral decubitus positions. Patients with a history of ocular surgery (not including vitrectomy) or recent medication use associated with IOP were excluded. IOP and ocular parameters of vitrectomized and normal fellow eyes were compared. For the decubitus position, IOP values of dependent and nondependent eyes were compared.

Results

No significant difference was observed in IOP between vitrectomized and normal eyes in the sitting and supine positions. The IOP for dependent eyes (on the lower side in the lateral decubitus position) was significantly higher than the IOP for nondependent eyes in both right lateral decubitus (right vitrectomized eye 19.31 ± 4.20 vs. 16.71 ± 4.02 mmHg, p < 0.001; left vitrectomized eye 18.35 ± 1.75 vs. 16.04 ± 3.02 mmHg, p = 0.003) and left lateral decubitus (right vitrectomized eye 17.32 ± 4.63 vs. 19.15 ± 3.83 mmHg, p = 0.004; left vitrectomized eye 16.19 ± 1.81 vs. 18.12 ± 2.29 mmHg, p < 0.001) positions.

Conclusions

IOP was higher in the dependent than the nondependent eye in the lateral decubitus position, for both vitrectomized and nonoperated eyes.

Risk factors for neovascular glaucoma after vitrectomy in eyes with proliferative diabetic retinopathy

Purpose

To investigate the potential risk factors for neovascular glaucoma (NVG) after vitrectomy in eyes with proliferative diabetic retinopathy.

Subjects and methods

In this retrospective, observational, comparative study, patients with proliferative diabetic retinopathy who underwent vitrectomy at Toho University Sakura Medical Center between December 2011 and November 2016 and who were followed for ≥12 months after surgery were included. Subject parameters examined included age, glycated hemoglobin (HbA1c), fasting blood glucose, administration of insulin, and estimated glomerular filtration rate. Ocular parameters examined included preoperative best-corrected visual acuity, preoperative IOP, operative history (specifically panretinal photocoagulation), lens status, ocular pathology (eg, iris/angle neovascularization, tractional retinal detachment, diabetic macular edema, vitreous hemorrhage, combined tractional retinal detachment), intraoperative retinal tamponade use, vitrectomy gauge, combined lens extraction/vitrectomy procedure, subsequent surgical procedures, and pre- and postoperative intravitreal bevacizumab. Correlations between variables and postoperative NVG development were examined using logistic regression analyses (backward elimination method).

Results

A total of 254 eyes of 196 consecutive subjects (146 men [74.5%], 54.0±10.8 years old) were included. Sixty of 254 eyes (23.6%) developed NVG. Several preoperative factors increased the risk of developing NVG, including iris/angle neovascularization (P=0.042), preoperative high IOP (P=0.005), low HbA1c (P=0.004), and administration of insulin (P=0.045). Intraoperative retinal tamponade also increased NVG risk (P=0.021, backward elimination method).

Conclusion

Preoperative parameters such as elevated IOP, iris/angle neovascularization, fasting blood sugar and HbA1c discrepancies, administration of insulin, as well as use of retinal tamponade during retinal surgery were identified as the risk factors for developing NVG.

Trends in the characteristics of vitrectomy in Eastern China

BACKGROUND

Several new instruments and techniques for pars plana vitrectomy (PPV) have been widely used in recent years, but information about the related characteristics of PPV in China is limited. To investigate the trends in the characteristics of PPV in Eastern China, an 8-year retrospective study was conducted.

PATIENTS AND METHODS

We collected data from patients who underwent PPV at the Eye, Ear, Nose and Throat Hospital of Fudan University, Shanghai, China, in November 2007, November 2011, and November 2015. Cases of trauma-related retinopathy were excluded. Data on the patient demographics, surgical procedures, and the prophylactic use of IOP-lowering medications were collected and analyzed.

RESULTS

In 2015, most PPVs were conducted with a 23-gauge system, whereas all PPVs in 2007 and 2011 were conducted with a 20-gauge system. The proportions of macular disease in the population in 2007, 2011, and 2015 were 9.1%, 10.7%, and 21.5%, respectively (P<0.001). The proportion of PPV that was combined with lens extraction and intraocular lens (IOL) implantation increased significantly from 12.81% in 2007 to 25.95% by 2015 (P<0.001). The proportions of patients treated with IOP-lowering drugs in 2007, 2011, and 2015 were 27.40%, 38.20%, and 12.60%, respectively (P<0.001). In 2007, systemic carbonic anhydrase inhibitors (CAI-Ss) and beta blockers (BBs) were the two main types of prophylactic IOP-lowering drugs administered, but their use had decreased in 2015 (P<0.001). The preventive use of adrenergic agonists (AAs), topical carbonic anhydrase inhibitors (CAI-Ts), and prostaglandin analogs (PGAs) became increasingly frequent from 2007 to 2015 (P<0.05).

CONCLUSION

The 23-gauge system, rather than the 20-gauge system, had become the mainstream PPV instrument by 2015. The proportion of macular disease patients requiring PPV in China clearly increased, and the rate of prophylactic IOP-lowering drug use decreased by 2015.

Risk factors for requirement of filtration surgery after vitrectomy in patients with proliferative diabetic retinopathy

PURPOSE

We retrospectively reviewed patients with postoperative neovascular glaucoma (NVG) after vitrectomy for proliferative diabetic retinopathy to investigate how variables assessed before, during, and after vitrectomy are associated with the requirement for filtration surgery.

PATIENTS AND METHODS

The subjects in this retrospective, observational, comparative study were 55 consecutive patients (61 eyes) who underwent vitrectomy for proliferative diabetic retinopathy at Toho University Sakura Medical Center between December 2011 and November 2016, were followed up for at least 6 months after surgery, and developed NVG within 2 years after surgery. They comprised 44 men and 11 women of mean age 52.4±9.1 years, who were followed up for a mean 7.1±6.1 months. We collected data on the following 16 variables: sex, age, history of panretinal photocoagulation completed within 3 months before vitrectomy, presence/absence of a lens, obvious iris/angle neovascularization, tractional retinal detachment, diabetic macular edema, vitreous hemorrhage, visual acuity and intraocular pressure before vitrectomy and at the onset of NVG, glycated hemoglobin, fasting blood glucose, estimated glomerular filtration rate, and use of intraoperative gas tamponade.

RESULTS

Logistic regression analysis with the backward elimination method identified preoperative fasting hyperglycemia (P=0.08), high intraocular pressure at the onset of NVG (P=0.04), and use of gas tamponade during vitrectomy (P=0.008) to be significant risk factors for requirement of filtration surgery.

CONCLUSION

Preoperative fasting hyperglycemia, high intraocular pressure at the onset of NVG, and use of gas tamponade during vitrectomy predispose patients to require filtration surgery in the event of postoperative NVG.

Effects of Vitrectomy and Lensectomy on Older Rhesus Macaques: Oxygen Distribution, Antioxidant Status, and Aqueous Humor Dynamics

Purpose

The purpose of this study is to evaluate effects of vitrectomy (PPV) and lens extraction with intraocular lens implantation (PE/IOL) on molecular oxygen (pO₂) distribution, aqueous humor antioxidant–oxidant balance, aqueous humor dynamics, and histopathologic changes in the trabecular meshwork (TM) in the older macaque monkey.

Methods

Six rhesus monkeys underwent PPV followed by PE/IOL. pO₂, outflow facility, and intraocular pressure (IOP) were measured. Aqueous and vitreous humor specimens were analyzed for antioxidant status and 8-hydroxy-2′-deoxyguanosine (8-OHdG), a marker of oxidative damage. TM specimens were obtained for immunohistochemical and quantitative PCR analysis.

Results

pO₂ at baseline revealed steep gradients in the anterior chamber and low levels in the posterior chamber (PC) and around the lens. Following PPV and PE/IOL, pO₂ significantly increased in the PC, around the IOL, and angle. IOP increased following both surgical interventions, with no change in outflow facility. Histopathologic analysis did not show changes in TM cell quantification, but there was an increase in 8-OHdG. Quantitative PCR did not reveal significant differences in glaucoma-related gene expression. Aqueous and vitreous humor analysis revealed decreased ascorbate and total reactive antioxidant potential and increased 8-OHdG in the aqueous humor only in the surgical eyes.

Conclusions

Oxygen distribution in the older rhesus monkey is similar to humans at baseline and following surgical interventions. Our findings of histopathologic changes of TM oxidative damage and alterations in the oxidant-antioxidant balance suggest a potential correlation of increased oxygen exposure with oxidative stress/damage and the development of open angle glaucoma.