Ischemic diabetic retinopathy may protect against nuclear sclerotic cataract

Vitrectomy as an Adjunct to Treat-and-Extend Anti-VEGF Injections for Diabetic Macular Edema: The Vitrectomy in Diabetic Macular Oedema (VIDEO) Randomized Clinical Trial

Importance

There are reported benefits from vitrectomy for diabetic macular edema (DME); however, data precede anti-vascular endothelial growth therapy (VEGF) therapy, supporting a need to assess the current role of vitrectomy.

Objective

To determine rates of recruitment and efficacy outcomes of vitrectomy plus internal limiting membrane (ILM) peeling adjunctive to treat-and-extend (T&E) anti-VEGF injections for diabetic macular edema (DME).

Design, Setting, and Participants

This was a single-masked, multicenter randomized clinical trial at 21 sites in the United Kingdom from June 2018 to January 2021, evaluating single eyes of treatment-naive patients with symptomatic vision loss from DME for less than 1 year. Inclusion criteria were best-corrected visual acuity (BCVA) Early Treatment Diabetic Retinopathy Study letter score greater than 35 (approximate Snellen equivalent, 20/200 or better) and central subfield thickness (CST) greater than 350 μm after 3 monthly intravitreal injections of ranibizumab or aflibercept. Data analysis was performed in July 2023.

Interventions

Patients were randomized 1:1 into vitrectomy plus standard care or standard care alone and further stratified into groups with vs without vitreomacular interface abnormality. Both groups received a T&E anti-VEGF injection regimen with aflibercept, 2 mg, or ranibizumab, 0.5 mg. The vitrectomy group additionally underwent pars plana vitrectomy with epiretinal membrane or ILM peel within 1 month of randomization.

Main Outcomes and Measures

Rate of recruitment and distance BCVA. Secondary outcome measures were CST, change in BCVA and CST, number of injections, rate of completed follow-up, and withdrawal rate.

Results

Over 32 months, 47 of a planned 100 patients were enrolled; 42 (89%; mean [SD] age, 63 [11] years; 26 [62%] male) completed 12-month follow-up visits. Baseline characteristics appeared comparable between the control (n = 23; mean [SD] age, 66 [10] years) and vitrectomy (n = 24; mean [SD] age, 62 [12] years) groups. No difference in 12-month BCVA was noted between groups, with a 12-month median (IQR) BCVA letter score of 73 (65-77) letters (Snellen equivalent, 20/40) in the control group vs 77 (67-81) letters (Snellen equivalent, 20/32) in the vitrectomy group (difference, 4 letters; 95% CI, -8 to 2; P = .24). There was no difference in BCVA change from baseline (median [IQR], -1 [-3 to 2] letters for the control group vs -2 [-8 to 2] letters for the vitrectomy group; difference, 1 letter; 95% CI, -5 to 7; P = .85). No difference was found in CST changes (median [IQR], -94 [-122 to 9] μm for the control group vs -32 [-48 to 25] μm for the vitrectomy group; difference, 62 μm; 95% CI, -110 to 11; P = .11).

Conclusions and Relevance

Enrollment goals could not be attained. However, with 47 participants, evidence did not support a clinical benefit of vitrectomy plus ILM peeling as an adjunct to a T&E regimen of anti-VEGF therapy for DME.

Trial Registration

isrctn.org Identifier: ISRCTN59902040.

Two-port dry vitrectomy for rhegmatogenous retinal detachment: a pilot study

OBJECTIVE

To evaluate the safety and efficacy of a new surgical technique for the management of primary rhegmatogenous retinal detachment (RRD), consisting of localized PPV near the retinal break(s), without infusion line, associated with a drainage of subretinal fluid and cryoretinopexy.

METHODS

Multicentric prospective study conducted at the University Hospital of Cagliari and IRCCS Fondazione Policlinico Universitario A. Gemelli, Roma. Twenty eyes affected by RRD with the causative retinal break(s) in the superior meridians were enrolled between February 2022 and June 2022. Patients with cataract ≥3, aphakia, significant posterior capsule opacification, giant retinal tears, retinal dialysis, history of trauma and PVR ≥C2 were excluded. All eyes underwent a two-port 25-gauge PPV with localized removal of the vitreous surrounding retinal break(s), followed by 20% SF6 injection and cryopexy. The surgical time was recorded for each procedure. Best-corrected visual acuity (BCVA) was measured at baseline and postoperative 6 months.

RESULTS

Primary anatomic success at 6 months was achieved by 85% of patients. No complications occurred, except for three (15%) retinal re-detachments. The average surgical time was 8.61 ± 2.16 min. Overall, the difference between pre- and last postoperative mean BCVA was statistically significant (p = 0.02).

CONCLUSIONS

Two-port dry PPV demonstrated safety and efficacy for the treatment of RRD, reaching an 85% of anatomical success rate. Although further studies are necessary to confirm the efficacy and long-term benefit of this treatment, we believe that this surgical technique could be considered a valid and safe alternative for the management of primary RRD.

Two-Port “Dry Vitrectomy” as a New Surgical Technique for Rhegmatogenous Retinal Detachment: Focus on Macula-on Results

We evaluated a new surgical technique for treating primary rhegmatogenous retinal detachment (RRD), consisting of localized vitrectomy near the retinal break associated with drainage of subretinal fluid without infusion. Twelve eyes of twelve patients with primary RRDs with macula-on superior, temporal, and/or nasal quadrants’ RRD with retinal breaks between 8 and 4 o’clock, pseudophakic or phakic eyes, were enrolled. All eyes underwent a two-port 25-gauge vitrectomy with localized removal of the vitreous surrounding the retinal break(s), followed by a 20% SF6 injection and cryopexy. The difference between pre-operative (T0) and post-operative mean BCVA at 6 months follow-up (T6) was not statistically significant (0.16 logMAR vs. 0.21 logMAR; p = 0.055). Primary anatomic success at 6 months was achieved by 86% of patients. No other complications, except for two retinal re-detachments linked to an incorrect head position of the patients, were recorded. Although further studies are necessary to evaluate the treatment’s efficacy, we believe our technique could be considered a valid alternative for managing primary RRD.

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.

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.

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.

Minimally interface vitrectomy for rhegmatogenous retinal detachment with a single break in young patients

Purpose

This study evaluates a new surgical technique consisting of minimal vitreous removal under air (minimal interface vitrectomy; MIV) to reduce postoperative complications while preserving the ability to address surgical factors at the retinal break.

Methods

This retrospective analysis examined the outcomes of minimal interface vitrectomies in consecutive cases, with a minimum 12-month follow-up period, of primary rhegmatogenous retinal detachment (RRD), recurrent RRD after pars plana vitrectomy (PPV), or failed surgery after primary scleral buckling surgery (SBS).

Results

Twelve eyes of 12 patients with RRD underwent MIV. The total surgical duration was 190–300 s (mean, 245.25 s). Eight (66.7%) eyes were treated with cryotherapy, and 4 (33.3%) with endolaser to seal the retinal break. Successful, complete retinal reattachment was achieved in all eyes and maintained during follow-up. No intra- or postoperative complications occurred and no patients developed inflammation or cataract during follow-up.

Conclusion and Importance

We effectively removed traction and subretinal fluid and treated breaks with endolaser or cryotherapy by using a novel minimal interface vitrectomy technique in this selected population.

Complications of vitreoretinal surgery

PURPOSE OF REVIEW

The present article reviews the most common and most serious vision-threatening and life-threatening complications of vitreoretinal surgery.

RECENT FINDINGS

Serious complications after vitreroretinal surgery are rare. Endophthalmitis for example has recently been estimated to occur in 0.08% of small gague vitrectomy. Other complications such as cataract are almost unavoidable, becoming visually significant in up to 80% of patients. The introduction of smaller gauge vitrectomy systems has reduced surgical times, conjunctival scarring and inflammation, and the rate of some complications such as retinal tears. Ocular venous air embolism is an exceedingly rare complication that is potentially life threating and therefore important for all vitreoretinal surgeons to be aware of.

SUMMARY

Though vitreoretinal surgery is well tolerated and effective, it is inevitable that all surgeons will experience complications and are therefore best served by understanding the potential complications, strategies to reduce the likelihood of them occurring, and ways to address them when they do happen.

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.

Surgical management of diabetic tractional retinal detachments

Tractional retinal detachment is an end-stage form of diabetic retinopathy that occurs when contractile forces in the vitreous and neovascular tissue lead to the detachment of the neurosensory retina. We review the literature related to the management of this disease. Preoperative planning includes appropriate patient selection, diagnostic and prognostic imaging, and medical optimization with reduction of systemic risk factors. Use of antivascular endothelial growth factor for preoperative treatment has had significant benefits for tractional retinal detachment repair in improving surgical efficiency and outcomes. Advances in microsurgical instrumentation are discussed, with attention to small-gauge vitrectomy with improved flow dynamics, viewing strategies, and lighting allowing bimanual surgery. Special emphasis is placed on bimanual surgical technique, choice of tamponade, and the avoidance of iatrogenic damage. Complications and special considerations are further explored. Based on our compilation of relevant literature, we propose a surgical algorithm for the management of these complex patients.

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.

Cost Evaluation of Early Vitrectomy versus Panretinal Photocoagulation and Intravitreal Ranibizumab for Proliferative Diabetic Retinopathy

PURPOSE

To evaluate costs and cost-utility of early vitrectomy (pars plana vitrectomy [PPV]) compared with panretinal photocoagulation (PRP) and intravitreal ranibizumab (IVR) for proliferative diabetic retinopathy (PDR) without diabetic macular edema.

DESIGN

A decision analysis model of cost-utility.

PARTICIPANTS

There were no participants.

METHODS

A decision analysis was based on results from the Diabetic Retinopathy Clinical Research Network Protocol S comparing treatment of PRP with IVR (0.3 mg) in PDR without incident macular edema to model the total 2-year costs and outcomes for each treatment scenario. These values were compared with the 2-year hypothetical costs of early PPV for PDR. Centers for Medicare and Medicaid Services data were used to calculate associated modeled costs in a hospital/facility-based and nonfacility setting. Cost-utility was calculated on the basis of the preserved visual utility and estimated life years remaining. In addition, costs for lifetime treatment were modeled for all scenarios and used to calculate lifetime quality-adjusted life years (QALY) costs for each scenario. Sensitivity analyses were performed to evaluate the impact of the model's assumptions.

MAIN OUTCOME MEASURES

Cost of treatment, utility, and cost per QALY.

RESULTS

The modeled cost per QALY of treatment for PDR for 2 years of utility in the facility (nonfacility) setting was $163 988 ($102 559) in the PRP group, $436 992 ($326 424) in the IVR group, and $181 144 ($107 965) in the PPV group. Sensitivity analysis showed that both IVR and PPV groups would have equivalent costs per QALY over the first 2 years if 78% (facility) and 80% (nonfacility) of patients in the PPV group required additional treatment with IVR (at the dose of 10.1 injections as in Protocol S). Beyond 2 years, the cost per QALY in the facility (nonfacility) setting was calculated as $61 695 ($21 752) in the PRP group, $338 348 ($239 741) in the IVR group, and $63 942 ($22 261) in the PPV group.

CONCLUSIONS

Early PPV as a strategy for treatment of PDR without macular edema demonstrates cost-utility similar to management with PRP and more favorable cost-utility compared with IVR in the short term. This advantage over IVR continues when lifetime costs are factored.

Vitrectomy without prone positioning for rhegmatogenous retinal detachments in eyes with inferior retinal breaks

Purpose

To compare the anatomic and functional outcomes of pars plana vitrectomy (PPV) for treating rhegmatogenous retinal detachments (RRDs) between two groups with and without postoperative prone positioning.

Methods

This retrospective cohort study included 142 eyes of 142 patients with a primary RRD. All patients underwent PPV with 20% sulfur hexafluoride gas tamponade and were divided into two groups: the groups that did and did not maintain a prone position postoperatively. All patients were followed for more than 3 months. The main outcome measures were the best-corrected visual acuity (BCVA), retinal reattachment rate, and postoperative complications.

Results

Sixty-five eyes were included in the prone position group and 77 eyes in the group without prone positioning; the respective initial reattachment rates were 83.1% and 96.1%, a difference that reach significance (p = 0.011). In the eyes with inferior breaks, the initial reattachment rate was 94.7% (18 eyes) without prone positioning, which was significantly (p = 0.036) better than the 60% (6 eyes) initial reattachment rate in the group with prone positioning. In the eyes without inferior breaks, there was no significant difference in the initial reattachment rates between the two groups. The BCVAs at the 3-month postoperative visit did not differ significantly between the two groups. An epiretinal membrane (ERM) was observed postoperatively in 10 (13.0%) eyes in the group without prone positioning; no ERMs were seen postoperatively in eyes in which the internal limiting membrane (ILM) was peeled during PPV.

Conclusions

PPV without postoperative prone positioning is associated with a higher reattachment rate in eyes with a RRD, especially those with inferior retinal breaks. PPV with postoperative supine and lateral positioning might be beneficial to manage RRDs associated with inferior retinal breaks if ILM peeling is performed intraoperatively.

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.

Refractive changes after lens-sparing vitrectomy for macular hole and epiretinal membrane

Purpose

Cataract progression after lens-sparing vitrectomy might differ according to original posterior segment diseases. Our objective was to analyze the refractive values after lens-sparing vitrectomy for macular hole (MH) and epiretinal membrane (ERM).

Materials and methods

We reviewed the medical records of 25 MH patients (25 eyes) and 23 ERM patients (23 eyes) who underwent lens-sparing vitrectomy. Refractive changes in both groups were compared. All patients underwent 20-gauge three-port pars plana vitrectomy. Fluid–air exchange was performed during vitrectomy only in the MH group. The results were analyzed using the unpaired t-test, chi-square test, or Fisher exact probability test, and multivariate analysis.

Results

There were no significant differences in the patient’s age (P=0.45). The myopia progression rate (D/month) was higher in the MH group after surgery than that in the ERM group (P=0.035). MH group had more females (P=0.043), longer surgical time (P<0.001), and higher frequencies of surgical adjuvants use (triamcinolone acetonide, P=0.019; brilliant blue G, P<0.001). The myopia progression rate in the MH group (R=0.568, P<0.001) correlated with female gender. However, no correlation was observed between longer surgical time and the use of surgical adjuvants.

Conclusion

The rate of myopia progression was higher in the MH group. Fluid–air exchange and gender may affect the rate of myopia progression.

Lens density measurement with Scheimpflug camera in vitrectomised eyes

OBJETIVE

To determine whether vitrectomised eyes have a higher lens optical density, when measured with a Scheimpflug camera, compared to non-vitrectomised eyes.

METHOD

The peak and linear Scheimpflug optical density (DOS), and area of both eyes were measured in a sample size of 81 vitrectomised phakic patients. A comparison was made between the DOS of the vitrectomised eye lens and the contralateral non-vitrectomised eye using the Student-t test.

RESULTS

A significantly higher linear DOS and area was obtained in the 81 vitrectomised phakic eyes when compared to the non-vitrectomised eyes (P<.001). The peak DOS is not significantly increased in respect to non-vitrectomised eyes (P=.59).

CONCLUSIONS

The lens DOS in vitrectomised eyes is higher than in non-vitrectomised eyes. The importance of the vitreous in the maintenance of lens transparency is emphasised.

αA-crystallin gene CpG islands hypermethylation in nuclear cataract after pars plana vitrectomy

PURPOSE

To investigate the DNA methylation status of αA-crystallin gene in cataract secondary to pars plana vitrectomy.

METHODS

Anterior capsular membranes of 40 eyes of 40 patients with cataract secondary to vitrectomy were collected. Another 20 eyes of 20 patients who received pars plana vitrectomy and phacoemulsification in the primary procedure, were recruited as control. Methylation status of the CpG islands of αA-crystallin gene was analyzed by pyrosequencing. Expression of αA-crystallin was evaluated by real-time polymerase chain reaction and western blot.

RESULTS

In the post vitrectomy group, five patients with posterior subcapsular opacity and four patients with cortical opacity were excluded from further analysis. The remaining 31 patients with nuclear cataract were assigned into two groups according to tamponade types: 19 of octafluoropropane (C3F8) and 12 of silicone oil (SiO). The average nuclear color grading was elevated both in C3F8 and SiO groups after vitrectomy. Compared to the control group, hypermethylation of the CpG islands in the αA-crystallin gene promoter was found in both post vitrectomy groups, accompanied by significantly reduced αA-crystallin expression. No statistically significant differences were found between the C3F8 and SiO groups either for DNA methylation status or αA-crystallin expression.

CONCLUSIONS

CpG islands hypermethylation of αA-crystallin gene may be involved in nuclear cataract formation after pars plana vitrectomy.

Refractive changes after lens-sparing vitrectomy for rhegmatogenous retinal detachment

PURPOSE

To evaluate refractive changes after lens-sparing vitrectomy for rhegmatogenous retinal detachment (RD).

DESIGN

Retrospective case series.

METHODS

A retrospective chart review was conducted in 66 eyes of 66 patients (50.0 ± 9.9 years old) who had undergone lens-sparing vitrectomy for rhegmatogenous RD. Spherical equivalent refractive power was evaluated before and 1, 2, 3, 6, 9, 12, and 15 months after vitrectomy. The relation between refractive changes and several parameters was investigated, such as axial length, presence of preoperative hemorrhage, preoperative spherical equivalent, retinal tear size, logMAR best-corrected visual acuity, number of laser photocoagulations, occurrence of postoperative vitreous hemorrhage, and degree of postoperative inflammatory reaction. Surgical parameters examined included operative time, wide-angle viewing system use, intraoperative adjuvant and gas tamponade use, vitrectomy system gauge, and surgeon.

RESULTS

Significant and continuous myopic shift was observed after vitrectomy throughout the study period. Spherical equivalent was not significantly different between the operated eyes and the fellow control eyes until 3 months after vitrectomy, but the operated eyes were significantly more myopic at 3 months and later postoperatively (P < .05). Of the 58 eyes finally included (8 patients lost to follow-up), 27 (47%) underwent cataract surgery after vitrectomy. Patients who underwent cataract surgery were significantly older than those who did not (P < .05); no other examined parameter was significantly different between groups.

CONCLUSIONS

A significant myopic progression occurred in eyes after lens-sparing vitrectomy for rhegmatogenous RD. A considerable amount of anisometropia occurred, even in the early postoperative period. Patient age was the only risk factor with the potential to advance the nuclear sclerotic cataract progression after vitrectomy.

Progression of nuclear sclerosis based on changes in refractive values after lens-sparing vitrectomy in proliferative diabetic retinopathy

Background

Nuclear sclerosis (NS) based on the Emery–Little classification and refractive values after lens-sparing vitrectomy was compared between proliferative diabetic retinopathy (DR) patients and nondiabetic patients.

Methods

Progression of NS based on the Emery–Little classification and changes in refractive values were compared between 13 proliferative DR patients (14 eyes, DR group) and 14 nondiabetic patients (14 eyes, non-DR group) who underwent lens-sparing vitrectomy. All patients revealed grade I NS based on the Emery–Little classification. Mean patient age and refractive value just after surgery were 56.07 years and −0.33 diopters (D) in the DR group, and 57.06 years and −0.96 D in the non-DR group.

Results

The Emery–Little classification in the DR group at 6 and 24 months postoperative were grade I (13 eyes)/grade II (one eye) and grade I (eleven eyes)/grade II (three eyes), respectively. Mean refractive values in the DR group at 6, 12, and 24 months postoperative were +0.28 D, +0.27 D, and +0.37 D, respectively. The Emery–Little classification in the non-DR group at 6 and 24 months (or preoperative for patients undergoing cataract surgery) were grade I (five eyes)/grade II (eight eyes) and grade I (zero eyes)/grade II (eight eyes)/grade III (five eyes), respectively. The mean refractive value in the non-DR group at 6 months postoperative was −3.20 D. All eyes exhibited myopic changes and progression of NS.

Conclusion

The findings of this study show that the progression of NS postvitrectomy is mild, even for DR patients 50 years of age or older, thus suggesting the need to reconsider the indications for simultaneous cataract surgery with vitrectomy.

An increase in phosphorylation and truncation of crystallin with the progression of cataracts

Background

Cataracts are the leading cause of blindness worldwide; however, there is no evidence regarding the direct formation of cataracts. At present, there is no treatment method other than surgery to prevent the formation or progression of cataracts.

Objective

Understanding the protein changes during various stages of cataracts might help realize the mechanism of the formation and progression of cataracts.

Methods

Lens materials were collected from cataract surgery. Cataracts were classified according to lens opacity using the gradation of the Lens Opacities Classification System. Lens proteins were separated by 2-dimensional polyacrylamide gel electrophoresis. Protein spots were visualized by Coomassie blue staining, and expression patterns were analyzed. Protein spots of interest were excised from 2-dimensional polyacrylamide gel electrophoresis gels, digested in situ with trypsin, and analyzed by mass spectrometry and liquid chromatographic tandem mass spectrometry.

Results

Crystallin was the major protein in the cataract lens, and αA, βB1, αB, and βA4 were the dominant types. Crystallin αB and βA4 increased with the formation of lens opacity. Moreover, phosphorylation and truncation of these proteins increased with the progression of cataracts.

Conclusion

Crystallin αB and βA4 and phosphorylation and truncation of crystallin in the lens might contribute to the formation of cataracts. In contrast, acetylation was not dominant in the progression of cataracts and did not play major role in the formation of cataracts.

Aging and age-related diseases of the ocular lens and vitreous body

Reduced quality of life and financial burden due to visual impairment and blindness begin to increase dramatically when individuals reach the age of 40. The major causes of age-related vision loss can be traced to changes to the structure and function of the lens, one of the tissues responsible for focusing light on the retina. Age-related nuclear cataracts, which are caused by aggregation and condensation of proteins, diminish vision because they impede the transmission and focusing of light on the retina. In addition to the slow-developing age-related form, cataracts often develop rapidly as a complication of ocular surgery, such as following vitrectomy or as a consequence of vitreous gel degeneration. Posterior capsular opacification, which can develop following cataract removal, is caused by proliferation and inappropriate accumulation of lens epithelial cells on the surfaces of intraocular lenses and the posterior lens capsule. Presbyopia is a loss of accommodative amplitude and reduced ability to shift focus from far to near objects. Onset of presbyopia is associated with an increase in lens hardness and reduced ability of the lens to change shape in response to ciliary muscle contraction. Avenues of promising research that seek to delay or prevent these causes of low vision are discussed in light of our current understanding of disease pathogenesis and some challenges that must be met to achieve success.

Computational model for oxygen transport and consumption in human vitreous

PURPOSE

Previous studies that measured liquefaction and oxygen content in human vitreous suggested that exposure of the lens to excess oxygen causes nuclear cataracts. Here, we developed a computational model that reproduced available experimental oxygen distributions for intact and degraded human vitreous in physiologic and environmentally perturbed conditions. After validation, the model was used to estimate how age-related changes in vitreous physiology and structure alter oxygen levels at the lens.

METHODS

A finite-element model for oxygen transport and consumption in the human vitreous was created. Major inputs included ascorbate-mediated oxygen consumption in the vitreous, consumption at the posterior lens surface, and inflow from the retinal vasculature. Concentration-dependent relations were determined from experimental human data or estimated from animal studies, with the impact of all assumptions explored via parameter studies.

RESULTS

The model reproduced experimental data in humans, including oxygen partial pressure (Po2) gradients (≈15 mm Hg) across the anterior-posterior extent of the vitreous body, higher oxygen levels at the pars plana relative to the vitreous core, increases in Po2 near the lens after cataract surgery, and equilibration in the vitreous chamber following vitrectomy. Loss of the antioxidative capacity of ascorbate increases oxygen levels 3-fold at the lens surface. Homogeneous vitreous degeneration (liquefaction), but not partial posterior vitreous detachment, greatly increases oxygen exposure to the lens.

CONCLUSIONS

Ascorbate content and the structure of the vitreous gel are critical determinants of lens oxygen exposure. Minimally invasive surgery and restoration of vitreous structure warrant further attention as strategies for preventing nuclear cataracts.

Long-term intraocular pressure changes after vitrectomy for epiretinal membrane and macular hole

Background

To investigate long-term intraocular pressure (IOP) changes after vitrectomy for epiretinal membrane (ERM) or macular hole (MH).

Methods

We retrospectively reviewed the medical records of 57 eyes with ERM and 61 eyes with MH that underwent vitrectomy. IOP levels and changes at 1, 3, 6, 12 months, and the final visit from baseline were evaluated in vitrectomized eyes and non-vitrectomized fellow eyes.

Results

In the ERM group, the mean follow-up period was 29.3 months; the mean preoperative IOP in the operated eyes was 12.9 ± 2.5 mmHg and the final IOP was 13.2 ± 2.9 mmHg. In the MH group, the mean follow-up period was 25.6 months; the mean preoperative IOP in the operated eyes was 13.3 ± 2.5 mmHg and the final IOP was 14.0 ± 3.2 mmHg. The mean final IOP of the fellow unoperated eyes was 13.0 ± 2.5 mmHg in the ERM group and it was 12.9 ± 3.2 mmHg in the MH group. A significant difference was found between the operated eyes and fellow eyes at the final visit in the MH group (P < 0.01) but not in the ERM group (P = 0.40). MH group was significantly at high risk of IOP increase after vitrectomy (P < 0.01).

Conclusions

IOP increase after vitrectomy was found in some eyes with MH during long-term follow-up but it was unlikely in eyes with ERM.

Small-gauge vitrectomy does not protect against nuclear sclerotic cataract

PURPOSE

To determine whether the gauge of vitrectomy instrumentation is associated with the progression of nuclear sclerotic cataract.

METHODS

A prospective interventional and observational study of patients undergoing vitrectomy surgery for various retinal conditions. Patients had Scheimpflug lens photography in the operated and fellow eye at baseline and at 6 months and 12 months after vitrectomy surgery.

RESULTS

Of 42 eyes included in the analysis, 11 had 20-gauge surgery, 22 had 23-gauge surgery, and 9 had 25-gauge surgery. In all operated eyes, vitrectomy surgery led to the significant progression of nuclear sclerotic cataract, compared with the fellow, unoperated eye. This small study was unable to detect a difference in nuclear sclerotic progression when comparing small-gauge surgery (23 and 25 gauge) with standard 20-gauge surgery.

CONCLUSION

Removal of the vitreous gel using any-gauge vitrectomy surgery leads to significant progression of nuclear sclerotic cataract at 6 months and 12 months. The findings are consistent with the hypothesis that the vitreous gel is important in protecting the lens from increased exposure to oxygen that leads to the formation of nuclear sclerotic cataract. This increased exposure to oxygen occurs as a result of removing the vitreous gel and is independent of the gauge of vitrectomy instrumentation.

Surgical and visual outcome following 20-gauge vitrectomy in proliferative diabetic retinopathy over a 10-year period, evidence for change in practice

INTRODUCTION

The study reports 10-year anatomical and visual outcome in patients who underwent pars plana vitrectomy (PPV) for complications due to proliferative diabetic retinopathy (PDR).

METHODS

Retrospective analysis of patients undergoing 20 G PPV from January 1999 to May 2010 for tractional retinal detachment (TRD) and non-clearing vitreous hemorrhage (NCVH) secondary to PDR recorded prospectively on an electronic patient record. The primary aim was to study anatomical success and eyes with visual acuity (VA) of ≤ 0.3 logMAR at last follow-up.

RESULTS

There were 346 eyes of 249 patients with mean age of 55.63 years and follow-up of 1.44 years. In all, 95.3% of eyes had a flat retina at final follow-up. Overall 136/346 (39.4%) eyes had final VA of logMAR ≤ 0.3 (Snellen 6/12) and 129 (37.3%) had logMAR ≥ 1.0 (Snellen 6/60). In all, 50/181 (27.6%) eyes with TRD and 84/165 (50.9%) with NCVH achieved final VA of ≤ 0.3 logMAR (Snellen 6/12). A total of 218 (63.1%) showed ≥ 0.3 logMAR improvement from baseline to last follow-up. Both preoperative VA and final postoperative (post-op) VA (P<0.001) improved significantly with each year from 1999 to 2010. The commonest peroperative complication was iatrogenic retinal tear formation (28.4%). This was a risk factor for the development of post-op retinal detachment, odds ratio: 3.90 (95% confidence interval: 1.91-7.97, P = 0.0002). Silicone oil was used in 5.2% of patients at the primary procedure. In all, 9.2% required removal of non clearing post vitrectomy hemorrhage.

CONCLUSIONS

Outcomes from vitreoretinal surgery for complications of diabetic retinopathy have improved. In addition, the visual outcome after diabetic vitrectomy steadily improved over the 10-year period, which may in part be due to the move to operate on patients with better vision.

Vitreoretinal influences on lens function and cataract

The lens is composed of a thin metabolically active outer layer, consisting of epithelial and superficial fibre cells. Lying within this outer shell are terminally differentiated, metabolically inactive fibre cells, which are divided into an outer cortex and central nucleus. Mature fibre cells contain a very high protein concentration, which is important for the transparency and refractive power of the lens. These proteins are protected from oxidation by reducing substances, like glutathione, and by the low-oxygen environment around the lens. Glutathione reaches the mature fibre cells by diffusing from the metabolically active cells at the lens surface. With age, the cytoplasm of the nucleus becomes stiffer, reducing the rate of diffusion and making nuclear proteins more susceptible to oxidation. Low pO(2) is maintained at the posterior surface of the lens by the physical and physiological properties of the vitreous body, the gel filling the space between the lens and the retina. Destruction or degeneration of the vitreous body increases exposure of the lens to oxygen from the retina. Oxygen reaches the lens nucleus, increasing protein oxidation and aggregation and leading to nuclear cataract. We suggest that maintaining low pO(2) around the lens should prevent the formation of nuclear cataracts.