Nuclear sclerotic cataract after vitrectomy for idiopathic epiretinal membranes causing macular pucker

Ascorbic acid export from human donor lenses: Is the lens a source of ascorbic acid in the ocular humors?

In previous work, we have shown that the lens acts a reservoir of the antioxidant glutathione (GSH), capable of exporting this antioxidant into the ocular humors and potentially protecting the tissues of the eye that interface with these humors from oxidative stress. In this study, we have extended this work by examining whether the lens acts as a source of ascorbic acid (AsA) to maintain the high levels of AsA known to be present in the ocular humors either by the direct export of AsA into the humors and/or by functioning as a recycling site for AsA, via the direct uptake of oxidised ascorbate (DHA) from the humors, its regeneration to AsA in the lens and then its subsequent export back into the humors. To test this, human lenses of varying ages were cultured for 1 h under hypoxic conditions and AsA/DHA levels measured in the media and in the lens. Human lenses were also cultured in compartmentalised chambers to determine whether efflux of AsA/DHA occurs at the anterior or posterior surface. Immunohistochemistry was performed on human donor lenses and sections labelled with antibodies against GLUT1, a putative DHA uptake transporter. Vitreous humor was collected from patients undergoing vitrectomy who either had a natural clear lens, an artificial intraocular implant (IOL) or a cataractous lens, and AsA/DHA and GSH and oxidised GSH (GSSG) measured. We found that cultured human donor lenses released both AsA and DHA into the media. Culturing of lenses in a compartmentalised chamber revealed that AsA and DHA efflux occurs at both surfaces, with relatively equal amounts of AsA and DHA released from each surface. The posterior surface of the lens was shown to express the GLUT1 transporter. Analysis of vitreous samples from patients undergoing vitrectomy revealed that vitreous GSH and AsA levels were similar between the natural lens group, IOL and cataractous lens group. Taken together, while human donor lenses were shown to export AsA and DHA into the surrounding media, the amount of AsA and DHA released from donor lenses was low and not sufficient to sustain the high levels of total AsA normally present in the humors. This suggests that although the lens is not the main source for maintaining high levels of AsA in the ocular humors, the lens may help to support local AsA levels close to the lens.

Refractive outcome in combined phacovitrectomy: Anterior segment changes and corrective factor for IOL power calculation improvement

PURPOSE

To analyze differences in refractive outcome Δ (difference between postoperative and expected refractive error) and in anterior segment changes between cataract surgery patients and combined phacovitrectomy patients. We also aimed to provide a corrective formula allowing to minimise the refractive outcome Δ in combined surgery patients.

METHODS

Candidates for phacoemulsification and combined phacovitrectomy (respectively PHACO and COMBINED groups) were prospectively enrolled in two specialised centres. Patients underwent best corrected visual acuity (BCVA) assessment, ultra-high speed anterior segment optical coherence tomography (OCT), gonioscopy, retinal OCT, slit lamp examination and biometry at baseline, 6 weeks postoperatively and 3 months postoperatively.

RESULTS

No differences in refractive Δ, refractive error and anterior segment parameters were noted between PHACO and COMBINED group (109 and 110 patients respectively) at 6 weeks. At 3 months, COMBINED group showed a spherical equivalent of -0.29 ± 0.10 D versus -0.03 ± 0.15 D in PHACO group (p = 0.023). COMBINED group showed a significantly higher Crystalline Lens Rise (CLR), angle-to-angle (ATA) and anterior chamber width (ACW) and a significantly lower anterior chamber depth (ACD) and refractive Δ with all 4 considered formulas at 3 months. For IOL power lower than 15, a hyperopic shift was observed instead.

CONCLUSIONS

Anterior segment OCT suggests anterior displacement of the effective lens position in patients undergoing phacovitrectomy. A corrective formula can be applied to IOL power calculation to minimize undesired refractive error.

Accuracy of intraocular lens formulas in combined phacovitrectomy

PURPOSE

To assess the refractive accuracy of eight intraocular lens (IOL) formulas in eyes that underwent combined phacovitrectomy.

METHODS

A retrospective chart review of 59 eyes that underwent uncomplicated phacovitrectomy between 2017 and 2020 at the Johns Hopkins Wilmer Eye Institute. Inclusion criteria were postoperative best corrected visual acuity of 20/40 or better within 6 months of surgery and IOL implantation in the capsular bag. The Barrett Universal II (BUII), Emmetropia Verifying Optical (EVOv2.0), Hill-Radial Basis Function (Hill-RBFv3.0), Hoffer Q, Holladay I, Kane, Ladas Super Formula (LSF), and SRK/T formulas were compared for accuracy in predicting postoperative spherical equivalents (SE) using Wilcoxon rank sum tests. Pearson's correlation coefficients were used to assess correlations between biometric parameters and errors for all formulas.

RESULTS

Prediction errors of SE ranged from - 1.69 to 1.43 diopters (D), mean absolute errors (MAE) ranged from 0.39 to 0.47 D, and median absolute errors (MedAE) ranged from 0.23 to 0.37 D among all formulas. The BUII had the lowest mean error (- 0.043), MAE (0.39) and MedAE (0.23). The BUII also had the highest percentage of eyes with predicted error within ± 0.25 D (51%) and ± 0.50 D (83%). Based on MedAE however, no pairwise comparisons resulted in statistically significant differences. Axial length (AL) was positively correlated with the error from the Hoffer Q and Holladay I formulas (correlation coefficients = 0.34, 0.30, p values < 0.01, 0.02 respectively).

CONCLUSION

While all eight IOL formulas had comparable accuracy in predicting refractive outcomes in eyes undergoing combined phacovitrectomy, the BUII and Kane formulas had a tendency to greater accuracy.

Japan-epiretinal membrane (J-ERM) registry: A prospective cohort study protocol investigating the surgical outcome of epiretinal membrane

BACKGROUND

Epiretinal membrane (ERM) causes visual impairment such as reduction in visual acuity and metamorphopsia due to retinal traction. With the improvement of optical coherence tomography (OCT) and microincision vitrectomy surgery (MIVS), the surgery of ERM has significantly advanced. However, there have been no large-scale studies on the following: (1) how to evaluate visual impairment in ERM, (2) the relationship between OCT findings and visual function, (3) when is the optimal timing of surgery, and (4) the relationship between the surgical instruments as well as techniques and prognosis. The purpose of this study was to obtain evidence regarding these ERM surgeries.

METHODS AND DESIGN

This is a prospective, multicenter cohort study of ERM surgery in Japan from March 1, 2023, to March 31, 2027 (UMIN000048472, R-3468-2). Patients who underwent ERM surgery during the study period and agreed to participate in this study will be included. The goal is to have a total of 5,000 eyes surgically treated for ERM. The following data will be collected: age, gender, medical history, subjective symptoms, visual function before and 6 and 12 months after surgery, clinical findings, OCT data, surgical technique, instruments used in surgery, and complications.

DISCUSSION

The results of this study will support the surgical decisions and procedures in ERM practices.

The effect of intraocular lens and lens eye on the treatment of macular splits in high myopia

BACKGROUND

Macular retinoschisis in patients with high myopia is one of the main reasons for a decline in visual function and the perceived deformation of visual objects.

OBJECTIVE

This study aimed to investigate the therapeutic effect of cataract phacoemulsification and foldable intraocular lens implantation (FILI) combined with internal limiting membrane stripping (ILMS) in the treatment of macular retinoschisis in patients with high myopia.

METHODS

A total of 52 patients (55 eyes) who had been diagnosed with macular retinoschisis with high myopia between June 2019 and June 2020 were enrolled in the present study. Patients in the control group (25 eyes) received 23G vitreous surgery and macular ILMS and long-term inert gas (C3F8) filling of the vitreous cavity; patients in the research group (30 eyes) were additionally treated with cataract phacoemulsification and soft intraocular lens on the same treatment basis as the control group.

RESULTS

The difference in average BCVA between the control and the research groups was not statistically significant before the surgery (P> 0.05) but was statistically significant 12 months after the procedure (P< 0.05). The minimum foveal thickness was significantly decreased in the two groups after the surgery compared with before the procedure (P< 0.05).

CONCLUSION

Cataract phacoemulsification and FILI further improved the therapeutic effect of ILMS in the treatment of macular retinoschisis in patients with high myopia.

Cataract Formation Following Pars Plana Vitrectomy in the Pediatric Population

PURPOSE

To analyze post-vitrectomy cataract formation in the pediatric population to elucidate the number of phakic children requiring cataract surgery following vitreous surgery and the perioperative factors affecting cataract development in these patients.

METHODS

Eyes of pediatric patients that underwent phakic pars plana vitrectomy (PPV) with no prior cataract in a 10-year period were included. Analyses evaluated relationships between patient age and time to cataract surgery, as well as contributing factors for cataract formation. Final visual outcomes were also examined. Outcomes were collected for patient age at first vitrectomy, indication for vitrectomy, use of tamponade agents, history of ocular trauma, cataract status, and time to cataract surgery from first vitrectomy.

RESULTS

Of 44 eyes analyzed, 27 (61%) were noted to have some degree of cataract formation. Of these, 15 (56%; 34% of total eyes) underwent cataract surgery. Use of octafluoropropane (P = .04) or silicone oil (P = .03) positively correlated with the need for cataract surgery in the total study group. Patients requiring cataract surgery had worse endpoint visual acuities than those who did not undergo surgery (P = .02), although this difference becomes less significant in follow-up over 2 years (P = .30). Patients who had cataracts but did not need cataract surgery showed an improvement in visual acuity (P = .04), but this was not demonstrated in patients who did need cataract surgery (P = .90).

CONCLUSIONS

Pediatric eye care providers should be aware of the significant risk of cataract formation following a phakic PPV. [J Pediatr Ophthalmol Strabismus. 2023;60(6):421-426.].

Comparison of simultaneous vs sequential pars plana vitrectomy and cataract surgery

BACKGROUND

To compare the clinical outcomes of patients undergoing sequential pars plana vitrectomy (PPV) followed by cataract extraction surgery (CE) [PPV/CE], simultaneous PPV and CE (PPV + CE), and sequential CE followed by PPV [CE/PPV].

METHODS

A retrospective observational cohort study of 427 eyes of 404 patients who underwent either sequential or simultaneous PPV and CE surgery between March 2016 and May 2021. Pre-operative and post-operative assessments (up to 2 years of follow-up visits) of uncorrected visual acuity (UCVA), corrected distance visual acuity (CDVA), spherical equivalent (SEQ), and refractive prediction error (RPE) was done. Main outcome measures were both visual (UCVA, CDVA) and refractive (RPE, SEQ).

RESULTS

There was a statistically significant difference in CDVA of the PPV/CE, PPV + CE, CE/PPV groups (logMAR 0.34 ± 0.40, 0.65 ± 0.61, and 0.55 ± 0.60, respectively) at one month postoperatively (POM1) (P < 0.001), and at the POM12 visits (logMAR 0.25 ± 0.34, 0.53 ± 0.68, and 0.44 ± 0.48; P = 0.04). In the subgroup analysis of patients with a diagnosis of either epiretinal membrane or vitreous opacities, there was no statistically significant difference in SEQ (P = 0.09) and RPE (P = 0.13) at the combined 1 month and 3 month visits.

CONCLUSION

Simultaneous PPV and cataract surgery demonstrated similar improvements in visual acuity and refractive outcomes, as well as comparable intraoperative and postoperative complication profiles to sequential surgery.

The Postvitrectomy Cataract

To review the recent literature regarding risk factors for cataract formation after vitrectomy, the challenges and management strategies for anterior segment surgeons when facing post-vitrectomy cataract surgery, and the visual outcomes of patients undergoing post-vitrectomy cataract surgery. Cataract surgery after vitrectomy can be safely performed to significantly improve the visual outcome in most post-vitrectomy patients, although final visual acuity is primarily limited by the patient’s underlying vitreoretinal pathology.

Predicting speed of progression of lens opacification after pars plana vitrectomy with silicone oil

Purpose

An increasing number of posterior segment disorders is routinely managed with pars plana vitrectomy (PPV). In older, phakic patients cataract formation is expected within the first two years after surgery. For younger patients its progression is individually fluctuating. This study uses an objective quantitative measurement for lens-status-monitoring after PPV with silicone oil to derive predictions for progression and severity of post-operative lens opacification evaluated in patients with rhegmatogenous retinal detachment (RRD).

Methods

Data acquisition was performed prospectively between March 2018 and March 2021. PentacamHR® Nucleus Staging mode (PNS) was used to objectively gather data about nuclear cataracts after PPV at different time points. Data was grouped into training and test sets for a mathematical prediction model. Via backward variable selection method a mathematical formula was set up by means of which predictions about lens densitometry (LD) can be calculated.

Results

20 males [58.8%] and 14 females [41.2%] matched the inclusion criteria (mean age 50.6 years [23–75; ±12.3]). Average follow-up was 8.1 months (3,4–17.4; ±3.4). Mean baseline LD of the treated and fellow eye before surgery was 11.1% (7.7%-17.6%; ±2.0) and 11.2% (7.7%-14.8%; ±1.5), respectively. Predicted LD values by the model for five pre-selected patients closely match the observed data with an average deviation of 1.06%.

Conclusions

Using an objective parameter like LD delivered by the PentacamHR® PNS mode additionally to the patient’s age allows us to make an individual prediction for any time after PPV with silicone oil due to RRD for all ages. The accuracy of the model was stronger influenced by baseline LD as cofactor in the equation than patient’s age. The application for the prediction lens opacification [which can be accessed for free under the following link (https://statisticarium.com/apps/sample-apps/LensDensityOil/)] can help vitreoretinal surgeons for patient consultation on the possibility to combine PPV with cataract surgery.

An objective evaluation of lens transparency after vitrectomy surgery with different intravitreal tamponades

PURPOSE

To evaluate and compare the effects of different intraocular tamponade agents on lens density after vitrectomy.

METHODS

The participating patients were divided into four groups according to the tamponade agent used: a sulfur hexafluoride (SF₆) group, a perfluoropropane (C₃F₈) group, a silicone oil group, and a no tamponade group. Lens density measurements were performed preoperatively and two weeks, one month, and three months postoperatively using a Pentacam HR device with a Scheimpflug camera. The postoperative values were compared with the preoperative baseline values, also the values were compared between the four groups.

RESULTS

The study included 82 eyes (82 patients). In the SF₆ group, lens density significantly increased in all zones two weeks and one and three months postoperatively (all P < .05). In the C₃F₈ group, lens density significantly increased in all zones three months postoperatively (all P < .01). In the silicone oil group, the zone 1, zone 2, and average lens density (ALD) value significantly increased one and three months postoperatively (all P < .05). In the no tamponade group, the zone 1, zone 2, and ALD values significantly increased three months postoperatively (all P < .05). There were no significant differences between the four groups in any zone either preoperatively or postoperatively (all P > .05).

CONCLUSIONS

Although increases in lens density were observed earlier in the tamponade groups than in the no tamponade group, between the groups over the follow-up period were no differences. We need the development of new surgical methods and materials to prevent post-vitrectomy lens damage in the future.

Hyperbaric oxygen as a model of lens aging in the bovine lens: The effects on lens biochemistry, physiology and optics

Age related nuclear (ARN) cataracts in humans take years to form and so experimental models have been developed to mimic the process in animals as a means of better understanding the etiology of nuclear cataracts in humans. A major limitation with these animal models is that many of the biochemical and physiological changes are not typical of that seen in human ARN cataract. In this review, we highlight the work of Frank Giblin and colleagues who established an in vivo animal model that replicates many of the changes observed in human ARN cataract. This model involves exposing aged guinea pigs to hyperbaric oxygen (HBO), which by causing the depletion of the antioxidant glutathione (GSH) specifically in the lens nucleus, produces oxidative changes to nuclear proteins, nuclear light scattering and a myopic shift in lens power that mimics the change that often precedes cataract development in humans. However, this model involves multiple HBO treatments per week, with sometimes up to a total of 100 treatments, spanning up to eight months, which is both costly and time consuming. To address these issues, Giblin developed an in vitro model that used rabbit lenses exposed to HBO for several hours which was subsequently shown to replicate many of the changes observed in human ARN cataract. These experiments suggest that HBO treatment of in vitro animal lenses may serve as a more economical and efficient model to study the development of cataract. Inspired by these experiments, we investigated whether exposure of young bovine lenses to HBO for 15 h could also serve as a suitable acute model of ARN cataract. We found that while this model is able to exhibit some of the biochemical and physiological changes associated with ARN cataract, the decrease in lens power we observed was more characteristic of the hyperopic shift in refraction associated with ageing. Future work will investigate whether HBO treatment to age the bovine lens in combination with an oxidative stressor such as UV light will induce refractive changes more closely associated with human ARN cataract. This will be important as developing an animal model that replicates the changes to lens biochemistry, physiology and optics observed in human ARN cataracts is urgently required to facilitate the identification and testing of anti-cataract therapies that are effective in humans.

Swept-source OCT reduces the risk of axial length measurement errors in eyes with cataract and epiretinal membranes

AIMS

To compare the biometric data from partial coherence interferometry (PCI) and swept-source OCT (SS-OCT) in patients with age-related cataract and epiretinal membrane (ERM): ERM, ERM with foveoschisis and macular pseudohole.

METHODS

49 eyes of 49 subjects including 36 ERM, 9 ERM foveoschisis and 4 macular pseudohole were analysed to evaluate the axial length (AL) measurements and the presence of AL measurement errors, defined basing on the shape of the biometric output graphs and on the concordance of AL values between instruments. Eyes with ERM were divided in four stages according to OCT features (i.e. presence/absence of the foveal pit, presence of ectopic inner foveal layers, disrupted retinal layers).

RESULTS

The devices provided similar mean AL measurements in all subgroups, with differences <0.1 mm in 41/49 cases (83.6%). AL measurement errors were observed in ERM stages 3 and 4, characterized by ectopic inner foveal layers, and were significantly more frequent with the PCI (8/17, 47%) as compared with the SS-OCT device (2/17, 12%), p = 0.02. The refractive prediction error in cases with AL measurement errors was significantly greater using the PCI compared to the SS-OCT device (p<0.05).

CONCLUSION

Both devices provide reliable biometric data in the majority of patients and can be used in the preoperative assessment of patients with age-related cataract and ERM. In eyes with ectopic inner foveal layers, attention should be paid as AL measurement and refractive prediction errors may occur, more frequently with the PCI device.

Effect of internal limiting membrane peeling on postoperative visual acuity in macula-off rhegmatogenous retinal detachment

PURPOSE

To investigate the effects of internal limiting membrane (ILM) peeling on visual acuity (VA) after rhegmatogenous retinal detachment (RRD) surgery.

METHODS

This retrospective analysis examined the medical records of patients with RRD who underwent vitrectomy at 26 institutions. To detect prognostic factors of VA at 6 months postoperatively (post-VA), multivariate linear regression was performed with post-VA as the objective variable; ILM peeling, sex, age, preoperative VA (pre-VA), intraocular pressure, axial length, duration of RRD, and cataract surgery served as explanatory variables. Recurrence of RRD and epiretinal membrane formation within 6 months postoperatively were compared between groups of patients with and without ILM peeling, among patients with macula-on and macula-off RRD.

RESULTS

The inclusion criteria were met by 523 eyes with a macula-on RRD and 364 eyes with a macula-off RRD. ILM peeling was performed in 85 eyes with a macula-on RRD and 57 eyes with a macula-off RRD. In eyes with a macula-on RRD, ILM peeling did not affect post-VA (p = 0.72). Vitrectomy without cataract surgery and poor pre-VA were significantly associated with poor post-VA (p = 0.01 and p < 0.001, respectively). In eyes with a macula-off RRD, ILM peeling, long duration of RRD, and poor pre-VA were significantly associated with poor post-VA (p = 0.037, p = 0.007, and p < 0.001, respectively). Recurrence of RRD and epiretinal membrane formation were similar between groups of patients with and without ILM peeling, among patients with macula-on and macula-off RRD. Retina sensitivity was not evaluated by microperimetry.

CONCLUSION

ILM peeling did not affect post-VA in eyes with a macula-on RRD, whereas post-VA was worse in eyes with ILM peeling than in eyes without peeling, among eyes with a macula-off RRD.

Lens densitometry for assessment and prediction of cataract progression after pars plana vitrectomy with C3F8-gas for retinal detachment

Purpose

Lens opacification is a common complication after pars plana vitrectomy (PPV) and knowing its progression would facilitate consulting patients. The purpose of this study was to evaluate a quantitative model for lens-status-monitoring after PPV with C3F8 gas. Our model was evaluated in rhegmatogenous retinal detachment (RRD) patients of various age and lens densitometry (LD).

Methods

Data between March 2018 and March 2020 were evaluated retrospectively. LD measurements of the PentacamHR® Nucleus Staging mode (PNS) were used to quantify lens opacification over time. A mixed-effect regression model was designed, to enable LD predictions at any time postoperatively. Calculations were based on patient’s age and baseline LD as dependent variables. Six patients were randomly excluded during model development, to be used for testing its power afterwards.

Results

34 patients (male 19 [55.9%], female 15 [44.1%]) matched the inclusion criteria. Average age was 58.5 years (32–77;±4.3) and average follow-up was 7.2 months (3,4–23.1;±1,8). Mean baseline LD of the treated and fellow eye before surgery were 10.9% (8.7%-14.8%;±0.8) and 10.7% (8.5%-14.1%;±0.6), respectively. Using our prediction model, LD values for the six pre-selected patients closely match the observed data with an average deviation of 1.07%.

Conclusions

Evaluation of age and baseline LD using a mixed-effect regression model might predict cataract progression in RRD patients treated with PPV and C3F8-gas. Such a tool could be considered during cataract surgery consultation in these patients.

Cataract Following Pars Plana Vitrectomy: A Review

Introduction: The indications for pars plana vitrectomy (PPV) have increased over the years. The vitreous is no longer considered an inert ocular structure and it is well known that its removal has anatomical and physiological consequences. The vitreous is no longer considered an inert ocular structure. The vitreous plays a key role as an intraocular physiologic oxygen regulator. In order to maintain its transparency, the crystalline lens needs protection from an excessive oxygen exposure. PPV leads to progression of nuclear sclerosis in most eyes.Methods: A systematic review of the literature was conducted using Embase and Medline databases. Articles studying the physiology, pathogenesis and surgical treatment of cataract after PPV were included in this review.Results: The pathogenesis of cataract formation after PPV remains unclear. Predisposing factors include advanced patient age, preexisting nuclear sclerosis, light toxicity, intraoperative oxidation of lens proteins, use of silicone oil or intravitreal gas, mechanical trauma and the duration of exposure to an irrigating solution.Conclusion: Cataract surgery in vitrectomized eyes presents with more technical difficulties, is more challenging and often has a higher risk of intraoperative and postoperative complications than in non vitrectomized eyes. There is no standardized technique or management in these cases; therefore, it requires more precautions during surgery.

Refractive outcomes of 8 biometric formulas in combined phacovitrectomy with internal limiting membrane peeling for epiretinal membrane

PURPOSE

To investigate the accuracy of 8 different biometric formulas in combined phacovitrectomy and the effect of constant optimization on refractive outcome.

SETTING

Ludwig-Maximilians-University, Munich, Germany.

DESIGN

Retrospective observational case series.

METHODS

In this single-center study, patients with cataract and epiretinal membrane who underwent combined phacovitrectomy with internal limiting membrane peeling (Group B) and axial length-matched patients who underwent phacoemulsification (Group A) were included. In Group C, optimized constants from Group A were applied in patients of Group B. One eye of each patient was included. Main outcome measures after constant optimization for each biometric formula were refractive prediction error (PE), mean absolute error (MAE), and percentages of eyes with a PE within ±0.25 diopters (D), ±0.5 D, and ±1.0 D.

RESULTS

The study comprised 128 patients. For all formulas in Group A and Group B, refractive PE was 0.000 (P = .964 and P = .967, respectively). For formulas Barrett, Haigis, Hill, Hoffer Q, Holladay 1, Holladay 2, Kane, and SRK-T, refractive PE was -0.147, -0.204, -0.180, -0.212, -0.180, -0.178, -0.153, and -0.159, respectively, in Group C (P = .569); MAE was 0.346, 0.375, 0.382, 0.379, 0.355, 0.377, 0.318, and 0.364, respectively, in Group A (P = .286); 0.402, 0.422, 0.417, 0.427, 0.417, 0.402, 0.370, and 0.401, respectively, in Group B (P = .364); and 0.401, 0.424, 0.419, 0.444, 0.424, 0.404, 0.391, and 0.422, respectively, in Group C (P = .767). Effect of constant optimization in phacovitrectomy was statistically significant for all formulas (P < .001 for each formula).

CONCLUSIONS

No statistically significant difference was observed between the biometric formulas with regard to PE and MAE. However, in terms of phacovitrectomy, constant optimization should be considered for individual intraocular lens power calculations attributable to myopic shift.

Prognostic Factors Associated with Ocriplasmin Efficacy for the Treatment of Symptomatic Vitreomacular Adhesion and Full-thickness Macular Hole: Analysis from Four Studies

Purpose

To assess the effect of patient baseline characteristics on the efficacy of ocriplasmin treatment for symptomatic vitreomacular adhesion (VMA) with full-thickness macular hole (FTMH) from phase 3/4 studies.

Methods

Patients with symptomatic VMA and FTMH at baseline and receiving ocriplasmin treatment 125 μg were pooled from the MIVI-TRUST, OASIS, and ORBIT studies. Multivariable logistic regression analysis was used to evaluate whether patient baseline characteristics were predictors of having VMA resolution by Day 28 and FTMH closure by Month 6.

Results

Two hundred and seventy-four patients receiving ocriplasmin treatment were assessed. Overall, 22.6% (62/274) of the patients experienced both VMA resolution by Day 28 and non-surgical FTMH closure by Month 6. Patients with FTMH ≤250 µm at baseline had a significantly higher success rate compared to those with FTMH >400 µm (29.9% [41/137] vs 2.2% [1/48]; P = 0.009). In patients with VMA resolution by Day 28, both small FTMH size (P = 0.001) and FTMH width at RPE (P = 0.012) were significantly associated with a higher FTMH closure rate. Patients with VMA resolution had higher rates of FTMH closure. Previously identified baseline predictive factors, including age, lens status, or presence of epiretinal membrane (ERM) were not found to be predictive of both VMA release and FTMH closure.

Conclusion

The analysis revealed that FMTH ≤250 µm was the only factor predictive for achieving both pharmacological VMA resolution by Day 28 and nonsurgical FTMH closure by Month 6; neither lens status or presence of ERM, previously identified baseline characteristics favoring VMA resolution, showed statistically significant predictive power for both outcomes.

Epiretinal membrane vitrectomy: outcomes with or without cataract surgery and a novel prognostic factor for cystoid macular edema

PURPOSE

To assess the outcomes of vitrectomy with or without cataract surgery for the treatment of idiopathic ERM in phakic eyes and evaluate predictors of functional and anatomical outcomes.

METHODS

Retrospective cohort of consecutive phakic ERM eyes distributed in three groups: a) combined (phacovitrectomy) group, b) PPV-only group, and c) consecutive group (PPV followed by cataract surgery). Main outcomes were final visual acuity (VA) and cystoid macular edema (CME) occurrence. Potential predictors of VA or CME included clinical variables and SD-OCT parameters.

RESULTS

A total of 108 eyes were included in this study. There were no differences in the final VA between consecutive and combined groups (0.22 vs 0.10 logMAR, p = 0.851). Twelve eyes from the combined group (23%) and one eye from the PPV-only group presented CME (p = 0.001). There were no differences between postoperative CME occurrence in combined versus consecutive group (12 vs 7, p = 0.38). The presence of cotton-ball sign predicted the development of CME [OR 2.86 (95%CI 1.01-8.18), p = 0.049] while separated ERM-ILM complex was found to be protective [OR 0.25 (95%CI 0.08-0.77), p = 0.015].

CONCLUSIONS

Functional and anatomical results of PPV with ERM and ILM peeling combined with cataract surgery was equivalent to the consecutive procedure, with both strategies being effective. Separated ERM-ILM complex has prognostic value in these patients, as its presence at baseline was found to be protective for postoperative CME.

Vitreoretinal surgeons' experience and time interval from pars-plana vitrectomy to cataract extraction

AIM

To identify the association of the vitreoretinal surgeons' experience with the time interval between pars-plana vitrectomy (PPV) and cataract extraction (CE).

METHODS

Eyes with prior PPV and following CE were included in this retrospective cohort study. The years of practice and the annual case volume were used to describe the surgeons' experience. Multivariable linear regression analysis was used to investigate the relationship between surgeons' experience and the time interval adjusted for the patients age, gender, intraocular tamponade, and case complexity.

RESULTS

Of 132 430 eyes, 1445 eyes were included in this study. In multivariable linear regression analysis, cases performed by surgeons with >20 practice years had longer time intervals compared with surgeons with <10 practice years after adjusted for other variables (β=0.329, 95%CI: 0.113 to 0.549, P=0.003). No difference in time interval was detected for comparing the lowest with the highest volume groups (β=0.089, 95%CI: -0.164 to 0.343, P=0.343). The surgeons' practice years were not directly with the volume. For complicated surgery, the higher-practice-year surgeons had longer time interval than lower-practice-year surgeons.

CONCLUSION

The time intervals from PPV to CE is longer in higher-practice-year surgeons. The surgeons' practice years may have a greater effect on the time interval than annual case volume in high-complexity cases. Matching the complexity of vitreoretinal diseases with the surgeons' practice year should be considered.

Vitamin C and the Lens: New Insights into Delaying the Onset of Cataract

Cataracts or clouding of the lens is the leading cause of blindness in the world. Age and diabetes are major risk factors, and with an increasing aging and diabetic population, the burden of cataracts will grow. Cataract surgery is an effective way to restore vision; however, alternatives to cataract surgery are required to reduce the looming cataract epidemic. Since it is well established that oxidative damage plays a major role in the etiology of cataracts, antioxidants have been promoted as therapies to delay and/or prevent cataracts. However, many antioxidant interventions including vitamin C have produced mixed results as anti-cataract therapies. Progress has been made towards our understanding of lens physiology and the mechanisms involved in the delivery and uptake of antioxidants to the lens which may guide future studies aimed at addressing some of the inconsistencies seen in previous animal and human studies. Of interest is the potential for vitamin C based supplements in delaying the onset of cataracts post vitrectomy which occurs in up to 80% of patients within two years. These targeted approaches are required to reduce the burden of cataract on hospitals and improve the quality of life of our aging and diabetic population.

Accuracy of New Generation Intraocular Lens Calculation Formulas in Vitrectomized Eyes

PURPOSE

To compare the prediction accuracy of new intraocular lens (IOL) calculation formulas (Barrett Universal II [BUII], Emmetropia Verifying Optical [EVO], Kane and Ladas Super formula) and traditional formulas (Haigis, Hoffer Q, Holladay 1, and SRK/T) with Wang-Koch (WK) axial length (AL) adjustment in vitrectomized eyes.

DESIGN

Retrospective consecutive case-series study.

METHODS

One hundred eleven eyes of 111 patients underwent uneventful phacoemulsification and enVista MX60 implantation after vitrectomy were enrolled and divided into 4 groups according to whether the vitreous cavity was filled with silicone oil. The performance of each formula was evaluated with or without lens constant optimization.

RESULTS

Before lens constants optimization, the mean prediction errors (MEs) of all formulas were statistically different from zero (0.14-0.46 diopters [D]) in vitrectomized eyes, except for the Kane formula. The BUII, EVO, Kane, and Haigis had relatively lower mean absolute error (MAE) and median absolute error (MedAE) with optimized constants. No significant systemic bias was found in new formulas for vitrectomized eyes with AL >26 mm (P > .05). The Hoffer Q and Holladay 1 displayed significantly hyperopic shift (0.39 and 0.51 D) for long eyes, which was corrected by the WK adjustment. There were no significant differences in the prediction accuracy of all formulas among 4 subgroups (P > .05).

CONCLUSIONS

The BUII, EVO, Kane, and Haigis displayed comparable performance in vitrectomized eyes with optimized constants. In vitrectomized highly myopic eyes, the new formulas and traditional formulas with WK adjustment exhibited satisfactory prediction accuracy. Silicone oil tamponade did not affect the prediction accuracy of formulas using IOLMaster 700.

Glutathione Improves the Antioxidant Activity of Vitamin C in Human Lens and Retinal Epithelial Cells: Implications for Vitreous Substitutes

PURPOSE

Tissues in the eye are particularly susceptible to oxidative damage due to light exposure. While vitamin C (ascorbic acid) has been noted as a vital antioxidant in the vitreous humor, its physiological concentration (1-2 mM) has been shown to be toxic to retinal and lens epithelial cells in in vitro cell culture. We have explored adding vitamin C to hydrogel vitreous substitutes as a potential therapeutic to prevent oxidative damage to intraocular tissues after vitrectomy. However, vitamin C degrades rapidly even when loaded at high concentrations, limiting its long-term effectiveness. Glutathione, another antioxidant found abundantly in the lens at concentrations of 2-10 mM, was proposed to be used in conjunction with vitamin C.

METHODS

Cell viability and reactive oxygen species activity of human retinal and lens epithelial cells treated with various combinations of vitamin C, glutathione, hydrogen peroxide, and a hydrogel vitreous substitute were determined using CellTiter-Glo luminescent cell viability assay and dichlorofluorescein assay, respectively. The vitamin C remaining in hydrogel vitreous substitute or glutathione-vitamin C solutions was determined using a microplate reader at 265 nm wavelength, compared against standard solutions with known concentrations.

RESULTS

Glutathione protected the lens and retinal cells from the negative effect of vitamin C on cell viability and prolonged the antioxidant effect of vitamin C in vitro. While the detected reading of pure vitamin C solution decreased rapidly from 100% to 10% by 3 days, glutathione provided a significant extension to vitamin C stability, with 70% remaining after 14 days when the glutathione was used at physiological concentrations found in the lens (2-10 mM).

CONCLUSIONS

These results indicate glutathione might be an effective addition to vitamin C in intraocular implants, including potential vitreous substitutes, and warrants additional studies on the effectiveness of the vitamin C - glutathione combination in preventing oxidative stress post-vitrectomy.

Unexplained Visual Loss After Silicone Oil Removal: A 7-Year Retrospective Study

Introduction

Unexplained visual loss after removal of silicone oil from the eye has been described. The purpose of this study is to determine the incidence of unexplained loss of visual acuity after SO removal and to provide possible explanations for this phenomenon.

Methods

This retrospective study included patients that underwent vitreoretinal surgery, at Centro Hospitalar São João, between January of 2012 and October of 2018. Inclusion criterion was vitreoretinal surgery in which the chosen endotamponade was SO, followed by removal of SO and exchange with balanced salt solution (BSS) or air. After SO removal, patients with documented loss of best corrected visual acuity (BCVA) on two or more Snellen lines were analyzed and patients in which the cause of the visual loss was identified, namely OHT (intraocular pressure > 21 mmHg), retinal re-detachment, glaucoma, retinal proliferative membrane formation, or corneal decompensation, were excluded. All patients with unexplained visual loss underwent spectral domain optical coherence tomography (SD-OCT) to exclude causes of visual reduction such as cystoid macular edema, epiretinal membrane, or ellipsoid/interdigitation zone disruption. A p value less than 0.05 was considered statistically significant.

Results

A total of 46 eyes underwent SO tamponade and SO removal during the study period. In 34.8% of the cases (n = 16) there was visual acuity loss in at least two Snellen lines. Of 46 eyes, 23.9% (n = 11) showed vision loss due to known secondary causes. Unexplained loss of visual acuity after SO removal occurred in 10.9% of cases. OHT during silicone endotamponade (p = 0.046) and silicone emulsification (p = 0.001) were identified as factors associated with unexplained visual loss after SO removal.

Conclusion

Unexplained loss of visual acuity after SO removal occurred in 10.9% of cases. OHT during silicone endotamponade and SO emulsification were identified as important factors in the ethology of this phenomenon.

Intraoperative Posterior Chamber Irrigation to Enhance Vitreous Cavity Support during Phacoemulsification Cataract Surgery after Vitrectomy

Purpose

To report the effectiveness of an intraoperative posterior chamber irrigation technique to enhance vitreous cavity support during postvitrectomy phacoemulsification cataract surgery.

Methods

The irrigation technique was performed during phacoemulsification cataract surgery on 10 postvitrectomy eyes (9 patients) with moderate or hard density cataracts and with low vitreous cavity support. A cohesive viscoelastic tamponade was applied to pressurize the anterior chamber to start the procedure. The vitreous cavity was then irrigated using a 26-gauge flushing cannula injecting balanced salt solution under the iris through the zonules, until the vitreous cavity pressure balanced and exceeded the anterior chamber pressure and viscoelastic flowed out from the corneal incision. Intraoperative performance with the irrigation technique, postoperative visual acuity, and anatomy, and complications were retrospectively evaluated.

Results

The irrigation procedure instantly enhanced posterior segment pressure before capsulorhexis in 4 eyes, before phacoemulsification in 4 eyes, after phacoemulsification in 2 eyes, before intraocular lens implantation in 6 eyes, and after implantation in 3 eyes. Phacoemulsification cataract surgery was facilitated by the irrigation technique, with a stabilized anterior chamber and robust vitreous cavity support. No complications occurred intraoperatively and postoperatively. At a 3-month follow-up, favorable visual and anatomic outcomes were achieved in all eyes.

Conclusions

The irrigation technique balanced the pressure of anterior and posterior segments. Thus, vitreous cavity support and anterior chamber depth were well stabilized during phacoemulsification cataract surgery in postvitrectomy eyes.

Combining cataract surgery with 25-gauge high-speed pars plana vitrectomy: A prospective study

PURPOSE

To compare visual outcome and postoperative complications of combined 25-gauge pars plana vitrectomy and phacoemulsification with vitrectomy alone surgery in patients with epiretinal membrane and macular hole.

METHODS

A total of 110 eyes (73 eyes with epiretinal membrane and 37 eyes with macular hole) were enrolled in this prospective study. The eyes were divided into two groups: Group A included 55 eyes which underwent phacovitrectomy at the same time and Group B included 55 eyes which underwent vitrectomy alone. Follow-up visits were at 1, 3, and 6 months.

RESULTS

The best-corrected visual acuity correlation by analysis of variance measurement showed statistically non-significant differences between the two groups (p = 0.32). The post hoc analysis from baseline, 1°, 2°, and 3° follow-ups was not statistically significant (p > 0.05). The most common postoperative complication was cystoid macular edema that has been detected in 11 patients (10%) (seven eyes in Group A and four eyes in Group B): 2 patients (1.8%) developed a chronic macular edema. Intraocular hypertension occurred in five eyes (4.5%) (three in Group A and two in Group B). Four eyes (3.6%) underwent another surgical procedure for a persistent macular hole (two in Group A and two in Group B). The intraocular lens repositioning was performed one day after surgery in three eyes (2.7%) (Group A). The mean preoperative visual acuity was not different between the two groups (p = 0.80).

CONCLUSION

No significative differences between combined surgery and vitrectomy alone have been detected, in terms of postoperative complications and visual outcome.

The Influence of Diabetes Status on the Rate of Cataract Surgery Following Pars Plana Vitrectomy

PURPOSE

We aimed to evaluate the association between diabetic status and the rates of cataract extraction (CE) following pars plana vitrectomy (PPV).

DESIGN

Retrospective cohort, multicenter database study.

PARTICIPANTS

Patients were selected from an insurance claims database (PharMetrics LifeLink) that included persons who had filed claims between 2006 and 2015 in the United States.

METHODS

We analyzed the records of 22 146 patients who underwent PPV performed by 2705 retina physicians. The vitrectomy group included patients ≥18 years of age who had undergone PPV. The control group included patients who were matched to the vitrectomy group 1:2 based on sex, diabetes mellitus (DM) status, region of the United States, and Charleston Comorbidity Index.

MAIN OUTCOME MEASURES

Hazard ratios (HRs) and rates of cataract surgery in patients with and without diabetes who had undergone prior PPV.

RESULTS

The hazard ratio for post-PPV CE was lower among patients with diabetes (3.307; 95% confidence interval [CI], 3.051-3.583) than among patients without diabetes (4.889; 95% CI, 4.670-5.119). This association was significant for all subgroups of patients with diabetes except in patients with diabetes and without retinopathy (4.086; 95% CI, 3.511-4.754). There was a significantly longer time between PPV and CE in patients with diabetes (537 days; 95% CI, 459-677 days) compared with those without diabetes (295 days; 95% CI, 278-312 days). The type of DM (type 1 vs. type 2) did not influence the rate of post-PPV cataract surgery. In persons with diabetes who underwent PPV, we observed a trend for a lower HR of cataract surgery in eyes with proliferative retinopathy (0.903; 95% CI, 0.725-1.124), and nonproliferative retinopathy (0.965; 95% CI, 0.721-1.290) compared with eyes with no retinopathy.

CONCLUSIONS

Eyes of patients with diabetes had a significantly decreased risk of undergoing CE after PPV surgery compared with eyes of patients without diabetes.

Effect of Pars Plana Vitrectomy With or Without Cataract Surgery in Patients with Diabetes: A Systematic Review and Meta-Analysis

INTRODUCTION

Pars plana vitrectomy (PPV) is considered to be an essential and effective surgical approach for the management of complications of diabetic retinopathy. Given the high rate of accelerated cataract progression after PPV, PPV combined with cataract surgery appears to be an attractive treatment option for patients with diabetes. However, this combined surgical approach remains controversial in terms of effectiveness and safety. We have therefore conducted a meta-analysis to evaluate the treatment outcome of PPV with or without cataract surgery.

METHODS

A systematic search of three electronic databases (PubMed, Web of Science, and the Cochrane Library) was performed to identify relevant articles, using the key words "pars plana vitrectomy," "cataract," and "diabetic retinopathy." Main outcome measures included the final visual acuity and postoperative complications. The incidence of postoperative complications was pooled using odds ratio (OR) with 95% confidence intervals in a random effect model.

RESULTS

Ultimately, one randomized controlled trial (RCT) and four high-quality retrospective studies met the inclusion criteria and were included in the meta-analysis. In four of these studies, final visual acuity did not vary significantly between patients undergoing PPV alone and those undergoing PPV combined with cataract surgery (combined surgery). Only one study reported better visual improvement in the combined treatment group. Our analysis also showed that most phakic eyes after PPV had cataract progression with varying degrees. In addition, patients receiving PPV alone had a lower risk of neovascular glaucoma (OR 0.36; P  < 0.05), iris synechias to anterior capsule (OR 0.36; P  < 0.05), and iris rubeosis (OR 0.26; P  < 0.05) compared with those receiving combined surgery.

CONCLUSION

Overall, our findings show that PPV combined with cataract surgery achieved good outcomes without a substantial increased risk to visual acuity or most complications. Given the high rates of cataract progression after PPV, combined surgery may be the more appropriate treatment for patients with diabetes and coexistent visually significant cataract.

Intraocular Oxygen and Antioxidant Status: New Insights on the Effect of Vitrectomy and Glaucoma Pathogenesis

PURPOSE

The purpose of this study was to investigate correlations of partial pressure of oxygen (pO₂) in the ocular anterior segment of human eyes and aqueous humor antioxidant levels of ascorbate (AsA) and total reactive antioxidant potential (TRAP) with glaucoma and vitreous status.

METHODS

This prospective, cross-sectional study stratified patients (n = 288 eyes) by lens and vitreous status and the presence of primary open-angle glaucoma for statistical analyses. Intraocular pO₂ concentrations were measured using a fiberoptic probe in patients at the beginning of planned glaucoma and/or cataract surgery. Aqueous humor specimens were obtained for antioxidant analysis of AsA and TRAP.

RESULTS

Following prior pars plana vitrectomy, pO₂ levels were significantly higher than in the reference group of cataract surgery in the anterior chamber angle (16.2 ± 5.0 vs. 13.0 ± 3.9 mm Hg; P = .0171) and in the posterior chamber (7.6 ± 3.1 vs. 3.9 ± 2.7 mm Hg; P < .0001). AsA and TRAP levels were significantly lower (1.1 ± 0.4 vs. 1.4 ± 0.5 mM, respectively; 403.3 ±116.5 vs. 479.0 ± 146.7 Trolox units, respectively; P = .004 and P = .024, respectively) in patients after vitrectomy. In patients with an intact vitreous, neither pO₂ nor antioxidant status correlated with lens status or glaucoma.

CONCLUSIONS

Increased pO₂ and antioxidant depletion following vitrectomy suggests an alteration of the intraocular oxidant-antioxidant balance. Our study links physiologic factors such as increased pO₂ in the anterior chamber angle and the posterior chamber to decreased antioxidant levels in aqueous humor following vitrectomy. Oxidative stress/damage to the trabecular meshwork in such post-vitrectomy cases may contribute to intraocular pressure elevation and increased risk of glaucoma. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

A Randomized Controlled Clinical Trial Comparing 20 Gauge and 23 Gauge Vitrectomy for Patients with Macular Hole or Macular Pucker

Introduction

To compare the transconjunctival sutureless 23 gauge (G) pars plana vitrectomy (PPV) with 20 G PPV regarding inflammation, safety, visual outcome and patient comfort.

Methods

We included 103 patients with symptomatic macular hole or macular pucker, scheduled for vitrectomy in this prospective, randomized, controlled, mono-center clinical trial. Patients were randomized 1:1 to either 20G PPV (n = 51) or 23G PPV (n = 52). All eyes underwent standard 20G or 23G PPV with membrane peeling. Primary outcome measure was change in aqueous humor flare 3 weeks after surgery compared with baseline. Secondary outcome measures were flare values 2 days and 26 weeks after surgery, subjective discomforts measured with a visual analog scale, best-corrected visual acuity, duration of surgery, intraocular pressure (IOP) and adverse events.

Results

There was no significant difference in change of flare 3 weeks after PPV [− 1.7, 95% CI (− 6.3 to 2.9), p = 0.466]. Both groups showed a significant increase in flare 2 days after surgery (20G: p < 0.001, 23G: p = 0.002), but only the 20G group after 3 weeks (p = 0.011). The gain in visual acuity after 3 weeks was higher after 23G PPV (4.2 95% CI (0.4–8.0, p = 0.029), but without a difference after 6 months. The duration of surgery was shorter in the 23G group (p < 0.001). Patient comfort 3 weeks after surgery was greater after 23G PPV (foreign body sensation p = 0.002; itching: p = 0.021). However, the rate of complications did not differ between the groups.

Conclusion

The primary aim, showing the superiority of the 23G group regarding the change of flare value from baseline to 3 weeks after surgery, was not met, but the level of inflammation decreased faster after 23G PPV. Clear advantages of the 23G PPV were a lower risk of postoperative IOP elevation, a shorter surgery time, faster visual recovery and greater patient comfort in the early postoperative phase.

Clinical Trial Registration Number

ClinicalTrials.gov NCT01969929.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0826-6) contains supplementary material, which is available to authorized users.

Long-Term Reproducibility of Axial Length after Combined Phacovitrectomy in Macula-sparing Rhegmatogenous Retinal Detachment

There is a myopic shift in the final measured spherical equivalent following combined phacovitrectomy compared to the predicted postoperative value. This change in myopia is known to be associated with gas tamponade, but it also occurs in patients who do not have gas tamponade, and even when vitrectomy is performed in the pseudophakic eye. In this study, we focused on the long-term reproducibility of axial length after combined phacovitrectomy in patients with macula-sparing rhegmatogenous retinal detachment. Before surgery, one year after surgery, and two years after surgery, bilateral axial lengths were measured using partial interferometry. To confirm whether axial lengths changed after surgery, we conducted confidence analyses using the intraclass correlation coefficient (ICC), coefficient of variation (CV), and test–retest standard deviation (TRTSD). The preoperative mean axial length was 25.03 ± 1.69 mm in the affected eyes and 24.96 ± 1.70 mm in the fellow eyes. The ICC, CV, and TRTSD were 0.97, 0.45, and 0.114 in affected eyes and 0.98, 0.66, and 0.167 in fellow eyes, respectively, which shows a high level of reproducibility. Prediction errors for postoperative spherical equivalents measured using partial interferometry were −0.41 ± 0.67 diopters (p = 0.001), respectively, which shows a remarkable myopic shift. Correlation analyses indicated that this myopic shift was significant in eyes with a shallower anterior chamber and a thicker lens. In macula-sparing RRD patients, the axial length showed excellent long-term reproducibility two years after vitrectomy, cataract surgery, and gas tamponade. The myopic shift after surgery was therefore caused by factors that may have affected the intraocular lens position, such as preoperative anterior chamber depth and lens thickness, rather than a change in the axial length.

Long-Term Safety and Efficacy of Limited Vitrectomy for Vision Degrading Vitreopathy Resulting from Vitreous Floaters

PURPOSE

Vitreous floaters can lower visual acuity (VA) and degrade contrast sensitivity function (CSF). Limited vitrectomy improves VA and normalizes CSF, but long-term results in a large series with objective quantitative outcome measures are lacking.

DESIGN

Case series.

PARTICIPANTS

One hundred ninety-five eyes of 145 patients (87 men, age = 57.6 ± 4.3 years; 58 women, age = 61.5 ± 12.0 years) reporting bothersome vitreous floaters were compared to 70 age-matched controls. Posterior vitreous detachment (PVD) alone was the cause in 96/195 (49.2%), myopic vitreopathy alone was the cause in 30/195 (15.4%), PVD with myopic vitreopathy was the cause in 56/195 (28.7%), and asteroid hyalosis was the cause in 13/195 eyes (6.7%).

METHODS

Limited vitrectomy with 25-gauge instruments was performed without surgical PVD induction, preserving 3 to 4 mm of retrolental vitreous in phakic eyes. Follow-up averaged 32.6 ± 23.5 months (range, 3-115 months), with 2 years or more in 144 eyes, 3 years or more in 69 eyes, 4 years or more in 51 eyes, and 5 years or more in 24 eyes.

MAIN OUTCOME MEASURES

Visual acuity, 39-item National Eye Institute Visual Function Questionnaire (VFQ) results, CSF (Weber index), and quantitative ultrasonography results.

RESULTS

After surgery, vitreous echodensity decreased by 94.1% (P < 0.0001) and VFQ results improved by 19.3% (P < 0.0001). Preoperative VA was 0.68 ± 0.21, improving to 0.77 ± 0.19 after surgery (P < 0.0001). Preoperative CSF was degraded by 91.3% compared with controls (P < 0.0001), normalizing at 1, 3, 6, 12, 24, 36, and 48 months after surgery (P < 0.00005 for each). There were no cases of endophthalmitis. There were 3 retinal tears and 3 retinal detachments that underwent successful repair. Clinically significant vitreous hemorrhage developed in 2 patients, clearing spontaneously. Two macular puckers and 4 recurrent floaters from new PVD were cured by re-operation. Cataract surgery occurred in 21 of 124 patients (16.9%; mean age, 64 ± 7 years; none younger than 53 years), an average of 13.1 ± 6.8 months after vitrectomy.

CONCLUSIONS

Limited vitrectomy for Vision Degrading Vitreopathy decreases vitreous echodensity, improves patient well-being, improves VA, and normalizes CSF. The long-term efficacy and safety profiles suggest this may be a safe and effective treatment for clinically significant vitreous floaters, warranting a prospective randomized trial.

DNA hypermethylation-mediated downregulation of antioxidant genes contributes to the early onset of cataracts in highly myopic eyes

High myopia is recognized as a risk factor for earlier onset of nuclear cataracts. One possible explanation for this is that lenses in highly myopic eyes are exposed to higher levels of oxygen than normal eyes owing to earlier vitreous liquefaction and, hence, are subjected to oxidative insults. Here, we first compared the methylation levels of six essential antioxidant genes (GSTP1, NRF2, OGG1, TXN, TXNRD1 and TXNRD2) between highly myopic cataract (HMC) and age-related cataract (ARC) lens epithelial samples via Sequenom MassARRAY. We found that specific CpG units in the promoters of GSTP1 and TXNRD2 were hypermethylated and that the expression levels of these two genes were lower in the HMC group than in the ARC group. A luciferase reporter assay confirmed the significance of differentially methylated fragments in the activation of transcription. The importance of GSTP1 and TXNRD2 in antioxidant capacity was confirmed by overexpression or knockdown experiments on cultured lens epithelial cells (LECs). In addition, the expression of DNA methyl transferase 1 (DNMT1) was higher in the lens epithelium of HMC patients than that of ARC patients, and the expression of GSTP1 and TXNRD2 was upregulated by use of a DNMT inhibitor in cultured LECs. Finally, we mimicked the intraocular environment of highly myopic eyes by treating LECs with hydrogen peroxide (H₂O₂) and observed both alterations in the methylation status of the GSTP1 and TXNRD2 promoters and time-dependent altered expression levels. Therefore, we propose that in an environment with high oxygen, in which lenses in highly myopic eyes are immersed, there exists a vicious cycle composed of increased oxidative stress and decreased enzymatic antioxidants via the hypermethylation of antioxidant genes.

•

Vitreous liquefaction generates a high-O2 environment surrounding the lens.

•

In highly myopic eyes, vitreous liquefaction occurs earlier and results in severer nuclear cataract.

•

Methylation levels of GSTP1 and TXNRD2 were elevated in lens epithelium of highly myopic eyes.

•

Increased oxidation and decreased enzymatic antioxidant via hypermethylation form a vicious circle in highly myopic eyes.

Optical Biometry-Based Intraocular Lens Calculation and Refractive Outcomes after Phacovitrectomy for Rhegmatogenous Retinal Detachment and Epiretinal Membrane

We investigate the refractive error after phacovitrectomy for rhegmatogenous retinal detachment (RRD; 100 eyes) and epiretinal membrane (ERM; 102 eyes). Axial lengths were measured by optical biometry in most patients. The main outcome measures were the refractive and absolute prediction errors. The overall mean refractive prediction error (ME) and mean absolute prediction error (MAE) were −0.40 ± 0.72 D and 0.62 ± 0.55 D, respectively, at 3 months postoperatively. The ME and MAE were significantly higher in the RRD group than in the ERM group (−0.63 ± 0.74 D vs −0.16 ± 0.63 D, P < 0.001 and 0.75 ± 0.62 D vs 0.49 ± 0.43 D, P = 0.002, respectively), indicating greater myopic shift in the RRD group. In the RRD group, adding +0.5 D to the preoperative predicted refractive power decreased the postoperative ME and MAE to −0.13 ± 0.74 D and 0.58 ± 0.47 D, respectively. Based on our results, we conclude that postoperative myopic shift was significantly higher in the RRD group than in the ERM group, possibly because of forward displacement of the intraocular lens by gas tamponade. The myopic shift can be minimized by adding +0.5 D to the predicted refractive power in patients undergoing phacovitrectomy for RRD.

Visual outcome and complications of cataract extraction after pars plana vitrectomy

Purpose

To evaluate the visual outcomes and complications of phacoemulsification in previously vitrectomized eyes.

Patients and methods

A retrospective analysis of 87 consecutive vitrectomized eyes (87 patients) which had undergone phacoemulsification with intraocular lens implantation between 2013 and 2016.

Results

The mean interval from pars plana vitrectomy (PPV) to cataract surgery (CS) was 18.8 months. Mean age at CS was 61.5 years. Intraoperative complications included anterior rhexis tear (1 eye) and hyphema (1 eye). Postoperative complications included macular edema (17.2%, mean 42 days), posterior capsule opacification (13.8%, mean 14 months), ocular hypertension (11.5%), and anterior uveitis (1.1%). Preoperative mean best-corrected visual acuity improved from 20/50 to 20/25. Ninety-one percent of the eyes gained 2 or more lines, and 95% achieved visual acuity ≥20/40 after CS. Preoperative mean spherical equivalent improved from -4.35 to -0.17. Eyes with clear lens prior to the PPV had later CS (clear lens 27.1 vs no clear lens 9.7 months; p=0.016). Patients >55 years with clear lens at PPV (n=21) had earlier CS than younger ones with clear lens (n=24) (11.8 vs 40.5 months; p=0.033). Mean follow-up was 14.5 months.

Conclusion

Phacoemulsification is a safe procedure in vitrectomized eyes, with substantial gains in vision in most cases. Patients of advanced age and eyes without clear lens prior to the PPV had earlier CS.

Surgical Outcomes of Idiopathic Epiretinal Membrane: the Gülhane Experience

Objectives:

We aimed to report our experiences and outcomes of vitreoretinal surgery in idiopathic epiretinal membrane.

Materials and Methods:

We retrospectively reviewed patients who underwent vitreoretinal surgery for idiopathic epiretinal membrane between January 2012 and 2014. The patients’ pre- and postoperative visual acuity, slit-lamp examination findings, and optical coherence tomography (OCT) images were evaluated.

Results:

Forty-five eyes of 45 patients (36% male, 64% female) were included (mean age, 69±8.2 years). Mean postoperative follow-up time was 7±4 (1-12) months. The mean preoperative logMAR best corrected visual acuity was 0.58±0.32 and postoperatively 0.40±0.31, 0.33±0.33, 0.28±0.34 respectively at 3, 6, and 12 months. All OCT parameters showed statistically significant anatomical improvement at 1, 3, 6, and 12 months. Correlation analysis showed that central macular thickness (r=0.69, p<0.05) and central macular volume (r=0.69, p<0.05) were the only parameters that had strong positive correlations with visual improvement.

Conclusion:

Epiretinal membrane causes heterogeneous anatomical changes in the macula for every patient. Therefore, a correlation between visual gain and changes in central macular thickness could not yet be demonstrated. We believe that central macular volume may be a better parameter for following these patients.

Epiretinal membrane surgery: an analysis of 2-step sequential- or combined phacovitrectomy surgery on refraction and macular anatomy in a prospective trial

PURPOSE

To assess the impact of combined phacoemulsification-vitrectomy and sequential surgery for idiopathic epiretinal membrane (ERM) on refractive error (RE) and macular morphology.

METHODS

In this prospective clinical trial, we allocated phakic eyes with ERM to (1) cataract surgery and subsequent pars plana vitrectomy (PPV) (CAT group), (2) PPV and subsequent cataract surgery (VIT group) or (3) phaco-vitrectomy (COMBI group). Examinations were at baseline, one month after each surgery, and at 3 months and 12 months of follow-up. Primary outcome was the RE (the difference between predicted and achieved spherical equivalent); secondary outcomes were best-corrected visual acuity (BCVA), and incidence of cystoid macular oedema (CME) defined as >10% increment of central subfield macular thickness (CSMT).

RESULTS

Sixty-two eyes were enrolled. The mean RE showed a small myopic shift of -0.36D in all groups 1 month after surgery, decreasing after 12 months to -0.17D. The absolute value of the RE (ARE) ranged 0.49-0.68D after 12 months. In the immediate postoperative period, there was a higher incidence of CME in the CAT group. There was no significant difference in final RE, ARE, BCVA and CSMT between the groups. Four cases (17%) in the CAT group had resolved visual complaints and improved BCVA after cataract surgery resulting in no need for PPV within the follow-up period.

CONCLUSION

Surgery for idiopathic ERM in phakic eyes with either phaco-vitrectomy or sequential surgery are equal approaches with respect to functional- (RE, BCVA) and anatomical outcomes (CME, CSMT). However, if starting with cataract surgery, 17% of the cases may not need subsequent PPV.

Primary Vitrectomy for Bullous Rhegmatogenous Retinal Detachments Due to Complex Breaks

Introduction

The role of vitrectomy for the treatment of uncomplicated retinal detachments has not been clearly defined. This study reports the results of a series of eyes with bullous rhegmatogenous retinal detachment (RRD) due to complex breaks that were managed by primary vitrectomy.

Methods

The study consisted of a consecutive series of 22 eyes (22 patients) with a bullous RRD not complicated by proliferative vitreoretinopathy (PVR) associated with large, multiple, or posterior breaks. All eyes underwent vitrectomy, injection of perfluorocarbon liquid (PFCL), cryopexy and gas tamponade as the primary procedure. Encircling scleral bands were placed in all cases. Follow-up ranged from 6 to 24 months (mean 10.9 ± 6.5 months).

Results

Anatomical retinal re-attachment was achieved in all eyes after one operation. Best-corrected final visual acuity was improved in all cases. Complications included progressive posterior subcapsular and nucleosclerotic cataract in four (22%) of the 18 phakic eyes and epiretinal membrane in one patient.

Conclusions

These results, together with the relatively low incidence of complications, lead us to conclude that this technique is an effective method for treatment of bullous RRD not complicated by PVR associated with technically difficult breaks. A controlled, prospective, randomized study would be necessary to thoroughly assess the advantages of vitrectomy over scleral buckling alone in these cases.

Treatment of Retinal Detachment with Giant Tear by Pneumatic Retinopexy

Nine eyes suffering from retinal detachment with giant tear were treated successfully by pneumatic retinopexy, followed by conventional buckling procedures and cryopexy. The retina in six of the nine eyes reattached after initial operation, whereas two required additional injection of SF6 gas. The remaining eye, having developed low-grade proliferative vitreoretinopathy (PVR C1), was treated successfully with vitrectomy. Visual outcome was rather poor immediately after the procedures due to vitreous opacity caused by gas injection. However, all cases showed excellent visual acuity five months after surgery. Visual field examined in six cases after surgery showed no significant constriction. If the retinal flap is mobile, pneumatic retinopexy may be effective in treating retinal detachment with giant tear.

Identification of H2O2 induced oxidative stress associated microRNAs in HLE-B3 cells and their clinical relevance to the progression of age-related nuclear cataract

BACKGROUND

This study is aimed to screen out the microRNAs (miRNAs) associated with H₂O₂ induced oxidative stress in human lens epithelial B3 (HLE-B3) cell lines and investigate their relations with the progression of age-related nuclear cataract.

METHODS

H₂O₂ was used to induce oxidative stress in HLE-B3 cells. A genome-wide expression profiling of miRNAs in HLE-B3 cells was performed to select the differentially expressed miRNAs before and after H₂O₂ treatment. The selected miRNAs were validated by RT-PCR and fluorescence in situ hybridization (FISH). Clinical specimens were divided into three groups according to the Lens Opacities Classification System III (LOCSIII) and the expression levels of the selected miRNAs were tested by RT-PCR in the three groups. Bioinformatics analyses were applied to predict the target genes of the miRNA hits and construct the miRNA regulatory network. The expression level of MAPK14 was analyzed by Western blot.

RESULTS

The H₂O₂ induced oxidative stress model of HLE-B3 cells was established. Nineteen upregulated and 30 downregulated miRNAs were identified as differentially expressed miRNAs. Seven of the total 49 were validated in the cell model. RT-PCR of the clinical samples showed that the expression levels of miR-34a-5p, miR-630 and miR-335-3p were closely related with the severity of nuclear opacity. The images taken from FISH confirmed the results of RT-PCR. There were 172 target genes of the three miRNAs clustered in the category of response to stress. The regulatory network demonstrated that 23 target genes were co-regulated by multiple miRNAs. MAPK14 was the target gene of three miRNAs and the result were verified by Western blot.

CONCLUSION

Up-regulation of miR-34a-5p and miR-630 and down-regulation of miR-335-3p are related with the progression of age-related nuclear cataract and the underlying mechanism awaits further functional research to reveal.

Phacoemulsification in Previously Vitrectomized Patients: An Analysis of the Surgical Results in 100 Eyes as well as the Factors Contributing to the Cataract Formation

Purpose

To evaluate the safety and effectiveness of phacoemulsification with clear corneal incision in previously vitrectomized patients as well as factors affecting the development time and type of cataract occurring after pars plana vitrectomy (PPV).

Methods

The authors conducted a prospective study of 100 consecutive eyes of patients who developed a cataract after PPV. Three groups were established based on the underlying vitreoretinal pathology. The main outcome measurements were intraoperative and postoperative complications and changes in best-corrected visual acuity (BCVA).

Results

The median interval between PPV and phacoemulsification was 11.5 months. Patients with proliferative diabetic retinopathy required phacoemulsification earlier (p=0.018). Posterior subcapsular cataracts developed more frequently in patients <50 years (73.7%, p=0.000) and affected those who underwent vitrectomy primarily for complicated retinal detachment (48.8%, p=0.046). Intraoperative complications included posterior capsular tears (4%), luxated nucleus into vitreous (2%), and zonular dialysis (5%). Postoperative complications were vitreous hemorrhage (6%), retinalredetachment (4%), pupillary synechiae (6%), ocular hypertension (4%), and Seidel phenomenon (3%). Posterior Nd:YAG laser capsulotomy was required in 44% of eyes. BCVA was improved in 85% of cases at the end of follow-up (median, 15.5 months). Twenty-one patients with one functioning eye (61.9%) demonstrated visual improvement compared with 79 patients with bilateral vision (91.1%; p=0.003).

Conclusions

The technique allows stable improvement in BCVA through long follow-ups. It is more risky than in nonvitrectomized eyes. The visual results after phacoemulsification in vitrectomized eyes seem to be limited by retinal comorbidity and surgical complications.

Surgery for postvitrectomy cataract

BACKGROUND

Cataract formation or acceleration can occur after intraocular surgery, especially following vitrectomy, a surgical technique for removing the vitreous that is used in the treatment of many disorders that affect the posterior segment of the eye. The underlying problem that led to vitrectomy may limit the benefit from removal of the cataractous lens.

OBJECTIVES

To evaluate the effectiveness and safety of surgery versus no surgery for postvitrectomy cataract with respect to visual acuity, quality of life, and other outcomes.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 5), MEDLINE Ovid (1946 to 17 May 2017), Embase.com (1947 to 17 May 2017), PubMed (1946 to 17 May 2017), Latin American and Caribbean Health Sciences Literature database (LILACS) (January 1982 to 17 May 2017), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com); last searched May 2013, ClinicalTrials.gov (www.clinicaltrials.gov); searched 17 May 2017, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 17 May 2017. We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

We planned to include randomized controlled trials (RCTs) and quasi-RCTs that had compared surgery versus no surgery to remove the lens from eyes of adults in which cataracts had developed following vitrectomy.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results according to the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We found no RCTs or quasi-RCTs that had compared surgery versus no surgery to remove the lens from eyes of adults in which cataracts had developed following vitrectomy.

AUTHORS' CONCLUSIONS

There is no evidence from RCTs or quasi-RCTs on which to base clinical recommendations for surgery for postvitrectomy cataract. There is a clear need for RCTs to address this evidence gap. Such trials should stratify participants by their age, the retinal disorder leading to vitrectomy, and the status of the underlying disease process in the contralateral eye. Outcomes assessed in such trials may include changes (both gains and losses) of visual acuity, quality of life, and adverse events such as posterior capsular rupture and retinal detachment. Both short-term (six-month) and long-term (one- or two-year) outcomes should be examined.

Postoperative Complications of Pars Plana Vitrectomy for Diabetic Retinal Disease

Despite recent advances in the medical management of diabetic retinal disease, there remain established indications for vitreoretinal surgery in the treatment of severe proliferative diabetic retinopathy. These include non-clearing vitreous hemorrhage and tractional retinal detachment. Advances in surgical instrumentation, technique, and experience have led to improved visual outcomes, as well as a corresponding decrease in the incidence of postoperative complications. However, the presence of systemic and ocular factors in diabetic patients increases the risk of adverse events compared to non-diabetic individuals. This review will focus on the most important postoperative complications following pars plana vitrectomy, with specific considerations for the diabetic patient.

The quantitative assessment of alterations in lens transparency after transconjunctival 27-gauge microincision vitrectomy surgery

PurposeTo evaluate the baseline and post-vitrectomy lens densitometry values by a Scheimpflug camera in eyes with epiretinal membrane that were treated with 27-G microincision vitrectomy surgery (MIVS) without tamponade and to compare the results with those in fellow healthy eyes.Patients and methodsProspective case series. The lens densitometry measurements of 24 patients, who underwent 27-G MIVS without any tamponade for the treatment of epiretinal membrane, were taken preoperatively and on the first week, first month, and third month postoperatively with Pentacam HR-Scheimpflug imaging system.ResultsThe mean lens densitometry values at Zone 1 and average lens densitometry values significantly increased in the study eyes on the first month when compared with the preoperative values (P=0.011, P=0.033, respectively). Additionally, there were statistically significant differences regarding the mean lens densitometry values of Zone 1 and Zone 2, and also average lens densitometry values between the preoperative and third month postoperative values (P=0.003, P=0.021, P=0.009, respectively). However, the densitometry values of fellow eyes were similar at preoperatively and all the postoperative follow-up periods (P>0.05 for all).ConclusionsThis study suggests that 27-G MIVS might cause post-surgical lens density changes even in early postoperative months and vitreous may play an important role in protecting the transparency of the lens.

SUPRACHOROIDAL BUCKLING FOR THE MANAGEMENT OF RHEGMATOGENOUS RETINAL DETACHMENTS SECONDARY TO PERIPHERAL RETINAL BREAKS

PURPOSE

To evaluate functional and anatomical outcomes of eyes undergoing suprachoroidal buckling for the management of peripheral retinal breaks in rhegmatogenous retinal detachment.

METHODS

Retrospective cohort study of 41 eyes of 41 patients undergoing suprachoroidal buckling for the management of rhegmatogenous retinal detachment secondary to single or multiple retinal breaks. Suprachoroidal indentation was achieved through the introduction of filler material using a 23-gauge (23-G) olive-tipped, suprachoroidal cannula. This allowed for the creation of a suprachoroidal dome and chorio-retinal apposition. Healon5 (Abbott Medical Optics) was used as filler material in all eyes. Combined 25-G vitrectomy was performed in 5 eyes. Cryopexy and laserpexy were used in 37 and 4 eyes, respectively.

RESULTS

Mean visual acuity gain was the primary outcome measure. Final retinal reattachment rate, single-surgery reattachment rate, and complications were secondary outcome measures. Mean best-corrected distance visual acuity improved from 20/1,100 to 20/42. Single surgery reattachment rate was 92.7% (38/41 eyes). Final retinal reattachment was achieved in all 41 eyes (100%). There was no statistically significant difference in visual acuity gain or anatomical reattachment in terms of retinal break quadrant or extent. No major complications were observed. Two localized suprachoroidal hemorrhages occurred at the entry site for the cannula. These resolved without further intervention.

CONCLUSION

Suprachoroidal buckling using a specially designed cannula is a safe and effective procedure for the management of rhegmatogenous retinal detachment secondary to peripheral retinal breaks.

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.

Evidence of Dual Mechanisms of Glutathione Uptake in the Rodent Lens: A Novel Role for Vitreous Humor in Lens Glutathione Homeostasis

Purpose

Lens glutathione synthesis knockout (LEGSKO) mouse lenses lack de novo glutathione (GSH) synthesis but still maintain >1 mM GSH. We sought to determine the source of this residual GSH and the mechanism by which it accumulates in the lens.

Methods

Levels of GSH, glutathione disulfide (GSSG), and GSH-related compounds were measured in vitro and in vivo using isotope standards and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis.

Results

Wild-type (WT) lenses could accumulate GSH from γ-glutamylcysteine and glycine or from intact GSH, but LEGSKO lenses could only accumulate GSH from intact GSH, indicating that LEGSKO lens GSH content is not due to synthesis by a salvage pathway. Uptake of GSH in cultured lenses occurred at the same rate for LEGSKO and WT lenses, could not be inhibited, and occurred primarily through cortical fiber cells. In contrast, uptake of GSH from aqueous humor could be competitively inhibited and showed an enhanced K_m in LEGSKO lenses. Mouse vitreous had >1 mM GSH, whereas aqueous had <20 μM GSH. Testing physiologically relevant GSH concentrations for uptake in vivo, we found that both LEGSKO and WT lenses could obtain GSH from the vitreous but not from the aqueous. Vitreous rapidly accumulated GSH from the circulation, and depletion of circulating GSH reduced vitreous but not aqueous GSH.

Conclusions

The above data provide, for the first time, evidence for the existence of dual mechanisms of GSH uptake into the lens, one mechanism being a passive, high-flux transport through the vitreous exposed side of the lens versus an active, carrier-mediated uptake mechanism at the anterior of the lens.